Ready Species One: Exploring the Use of Augmented Reality to Enhance Systematic Biology with a Revision of Fijian Strumigenys (Hymenoptera: Formicidae)

Abstract Advances in technology are rapidly changing the way people transmit, view, and interact with information. These advances offer new opportunities for researchers to share scientific discoveries with each other and the general public as never before. The field of revisionary biology has audiences confined to small groups of specialists, but the core task of systematic biology—documenting the endless forms of nature—is particularly well suited to capitalize on innovations in the realm of virtual, mixed and augmented reality. Interactive three-dimensional (3D) digital models of biological specimens can help bridge barriers across scientific disciplines by circumventing technical jargon, and also promise to open exciting new vistas for public engagement. Here, we explore the potential of augmented reality for communicating the discovery of new species. As a test case, we revise a radiation of Strumigenys Smith (Hymenoptera: Formicidae) miniature trap-jaw ants in Fiji. In addition to traditional revisionary elements, we present the augmented reality application ‘Insects3D’ built specifically for this study. The application runs on mobile devices and allows users to interact with X-ray microtomography-derived 3D specimen models and visualize 3D geographic distribution maps. We recognize 23 species in Fiji, including 6 new species: S. anorak n. sp., S. artemis n. sp., S. avatar n. sp., S. gunter n. sp., S. oasis n. sp., and S. parzival n. sp. This study demonstrates the potential of leveraging 3D data and technology for a more interactive systematic biology, and the need for research programs to develop robust and generalized tools to realize this potential.

Taxonomy-the science of classifying life on earth-is foundational to organismal biology. As elder statesmen of biodiversity science have noted, 'The goal of discovering, describing, and classifying the species of our planet assuredly qualifies as big science' . During the turn of the 21st century, the scientific community began discussing both the biodiversity crisis and the taxonomic impediment: the pace of species extinction was accelerating even as taxonomic research was losing prestige, resources, and talent (Pimm et al. 1995, Godfray 2002, Godfray and Knapp 2004, Wheeler 2004. Were taxonomists to thrive in the molecular era, taxonomy would need to adapt.
Two crucial developments of taxonomy in the 21st century are the integration of molecular evidence and the adoption of new specimen imaging technologies. The marriage of molecular data to traditional morphology has made taxonomy a more robust science. Genetic analysis has proved indispensable for stabilizing higher level classification, rooting out morphological homoplasy, and providing early scaffolds for large taxonomic revisions (Padial et al. 2010, Schlick-Steiner et al. 2010. Although taxonomy benefits from the integration of molecular data, the discipline remains rooted in descriptive and analytical morphology. In this respect, the integration of new imaging technologies has arguably had more impact on the scientific quality and clarity of new species descriptions than has the inclusion of genetic data. Modern imaging is especially crucial for studying small invertebrates, which compose the majority of both described and undescribed species. As example, the broad adoption of focus stacking technology during the past two decades has revolutionized photography of arthropod specimens by eliminating depth of field constraints (Blagoderov et al. 2012, Brecko et al. 2014). In addition Insect Systematics and Diversity, (2019) 3(6): 6; 1-43 doi: 10.1093/isd/ixz005 Research to enhancing the quality of new species descriptions, online image repositories of type specimens enable faster species descriptions by reducing time-intensive museum visits and specimen loans.
The most compelling advances in biological specimen imaging are arguably coalescing around three-dimensional (3D) imaging and processing technologies capable of generating virtual specimen models. The two most prevalent 3D imaging technologies used by organismal biologists-and invertebrate zoologists in particular-are micro-computed tomography (micro-CT) (Faulwetter et al. 2013, Akkari et al. 2015, Hita Garcia et al. 2017b, Ijiri et al. 2018) and photogrammetry (Nguyen et al. 2014, Gutiérrez-Heredia et al. 2015, Qian et al. 2015, Galantucci et al. 2016, Gutierrez-Heredia et al. 2016, Sosa et al. 2016. Although 3D imaging of biodiversity collections is in its infancy, access to micro-CT scanners in biology departments and natural history institutions is increasing. Simultaneously, more cost-effective photogrammetry systems are being developed. Consequently, biologists are publishing large datasets of 3D specimen models on websites such as Sketchfab (Sketchfab 2018), Zoosphere (Zoosphere 2018), and Morphosource (Morphosource 2018, Watkins-Colwell et al. 2018. The expanding availability of 3D specimen data is coinciding with a bourgeoning array of tools for 3D model visualization. Augmented reality (AR), for example, is an emerging technology capable of superimposing 3D computer-generated images on a user's view of the real world. As testament to the technology's growth, the global augmented reality market was valued at USD 3.33 billion in 2015 and is expected to reach approximately between USD 80 and 130 billion in 2021 (Zion Market Research 2017). Whereas users view only computer-generated images in virtual reality (VR), the view in AR is a composite of the real world and virtual world. Our focus on AR, rather than VR, acknowledges that while access to the head-mounted displays (HMDs) required for experiencing VR is currently limited, nearly everyone carries an AR compatible mobile device, such as a smartphone or tablet.
Biological applications of augmented reality have primarily been the provenance of the medical field (Azuma 1997). Comparatively little attention has been given to the implications of AR for biodiversity research and outreach (Bimber et al. 2002, White et al. 2006, Yeh et al. 2006, Barry et al. 2012, Chiang et al. 2014, Seltmann et al. 2017. Moreover, the application of AR to taxonomic research has thus far received mention in passing only (Sosa et al. 2016). The lack of connectivity between taxonomic research and AR is somewhat surprising, as museums are both integral to taxonomic research and among the earliest institutional adopters of AR technology (Wojciechowski et al. 2004, Debenham et al. 2011, Yoon et al. 2012. On the basis of our literature review, we are unaware of any published taxonomic studies that explicitly include visual markers for displaying specimen models in augmented reality. In previous contributions Sarnat et al. 2016Sarnat et al. , 2017Agavekar et al. 2017;Hita Garcia et al. 2017b, 2017aStaab et al. 2018), we focused on the use of 3D X-ray imaging for systematics. The aforementioned studies included passive media (e.g., 3D models flattened into 2D figures, video of rotating 3D models) and interactive media (e.g., rotatable 3D models embedded in interactive PDFs). Here we explore how 3D imaging technology can create immersive media for use in organismal biology.

Statement of Purpose
In this paper, we present proof-of-concept examples for how augmented reality can add research value to systematic biology. Specifically, we demonstrate how mesh models generated from the morphological and geographic data of newly described Strumigenys Smith, 1860 (Hymenoptera: Formicidae) ants can be viewed and manipulated in three dimensions using commonplace mobile devices. We present methods and results for all stages of AR deployment, including specimen scanning, mesh model creation, marker development, and mobile app development. We conclude our discussion by critiquing opportunities and challenges for using AR technologies to enhance biodiversity research, education, and outreach. The study provides direction for future integration of emerging technologies such as augmented reality and virtual reality into specimen-based research.

Strumigenys
The taxonomic focus of the study presented here are Strumigenys ants from the Fiji Islands. Strumigenys-known also as miniature trap-jaw ants-are diminutive predators that specialize in capturing minute arthropods. These huntresses most often nest and forage in leaf litter, topsoil and decaying wood and form small and usually monogynous colonies (Bolton 1999). The most prevalent prey are entomobryomorph Collembola, but they will take other small arthropods as well (Wilson 1954, Brown 1971, Masuko 1985, Dejean 1987. Strumigenys species are primarily distributed across tropical and subtropical rainforests and are most commonly collected using leaf litter extraction methods such as Berlese funnels or Winkler traps.
Strumigenys ants are striking in appearance. They exhibit elongated, pyriform heads flattened along the dorsoventral axis. They produce a rich variety of highly modified hairs from thick, flattened, and spatulate to gossamer thin, thread-like, and twisting. Nearly all produce mysterious sponge-like outgrowths referred to as spongiform appendages that emanate from the waist. The mandibles of many are shaped into outlandishly long levers spiked at the tip with long piercing teeth.
Long-mandible Strumigenys are commonly referred to as trapjaw ants on account of their mandibles' spring-loading mechanism which is triggered to snap shut by the touch of suitable prey. Though trap-jaw mechanisms evolved in at least three ant subfamilies and nine genera, the vast majority of trap-jaw ants belong to the genus Strumigenys (Larabee and Suarez 2014). Not all of the 800+ described Strumigenys species ) are trap-jaw ants. Many species previously placed in distinct genera on account of their variant jaw shape or number of antennal segments (Bolton 2000) are now placed in Strumigenys based on molecular evidence of shared ancestry (Ward et al. 2015). The taxonomic history of Strumigenys has been extensive and occasionally contentious (Baroni Urbani and de Andrade 2006, Bolton 2006. A comprehensive list of taxonomic studies treating Strumigenys is included in Bolton (2000) and Baroni Urbani and de Andrade (2007).
The tropical islands of the Fijian archipelago host an exceptionally rich fauna of Strumigenys. In total, 23 species are now known from the archipelago, including 6 that are described here for the first time. Two species (S. membranifera Emery and S. rogeri Emery) are introduced from Africa and an additional tramp species (S. godeffroyi Emery) is most likely native to Southeast Asia. The remaining 20 species are considered endemic to Fiji, although 1 species (S. mailei Wilson & Taylor) is also recorded from Samoa.
The first treatment of Fiji's Strumigenys species was presented by Mann (1921) in his monograph on the archipelago's ants. In addition to listing S. godeffroyi, Mann described five species-S. jepsoni, S. nidifex, S. scelestus, S. vitiensis, S. wheeleri-although the latter two were later synonymized with S. membranifera and S. tumida Bolton, respectively. A key to these six species was included and the genus was briefly discussed with respect to the high number of species on the archipelago. Wilson and Taylor (1967) described S. mailei from Samoa, and designated as paratype a worker collected from the uplands of Viti Levu by E.C. Zimmerman in 1938. Dlussky (1993) described S. chernovi from Fiji in a study of the southwestern Pacific Strumigenys. Bolton (2000) described eight new species of Fijian Strumigenys in his global revision of Strumigenys (S. basiliska, S. daithma, S. ekasura, S. frivola, S. panaulax, S. praefecta, S. sulcata, S. trauma (= Pyramica trauma) and provided S. wheeleri Mann with the replacement name S. tumida. Sarnat and Economo (2012) presented a diagnostic key, species accounts, specimen photographs, and distribution maps for all the valid Strumigenys known from Fiji along with seven putatively undescribed species. After further review of these seven morphospecies discussed in Sarnat and Economo (2012) we propose here that five represent new species (S. anorak n. sp., S. artemis n. sp., S. avatar n. sp., S. gunter n. sp., and S. oasis n. sp.). Comparison with additional type material also suggests that the specimens treated in Sarnat and Economo (2012) as S. panaulax Bolton constitute a distinct species, described here as S. parzival n. sp.
The present work is an ongoing effort (Sarnat 2006;Lucky and Sarnat 2008;Sarnat 2008;Economo 2012, 2013;Hita Garcia et al. 2015;Fischer et al. 2016) to describe Fiji's rich and highly endemic ant fauna. Taxonomy is the foundation of organismal biology, and these morphological studies have prompted new hypotheses concerning taxon cycles Sarnat 2012, Matos-Maraví et al. 2018a), island biogeography (Lucky and Sarnat 2010, Sarnat and Moreau 2011, Clouse et al. 2015, Matos-Maraví et al. 2018b, and functional ecology . The Fijian Strumigenys are a model group for studying rapid morphological and ecological radiation of social insects on island systems. Analysis of molecular data from a global sampling of Strumigenys suggests the long-mandible Fijian endemics are all descended from a single colonist ancestor (Liu et al. unpublished data). The in situ evolution of such dramatic morphological disparity strongly contradicts previous biogeographic hypotheses based on morphological observation. Bolton assigned each of Fiji's native and endemic Strumigenys to species groups (Table 1). Given that none of the listed groups or complexes are composed strictly of Fijian species, Bolton's assignments assume Fijian endemic Strumigenys are descended from no fewer than six independent colonization events.
Although the meticulous global revision was explicit that many of the Fijian species did not neatly conform to their assigned groupsand that the assignments more accurately reflected morphological similarity than phylogenetic proximity-the extent of evolutionary convergence with distantly related Indoaustralian congeners was not anticipated by Bolton (2000) or Sarnat and Economo (2012). That all long-mandible Fijian endemic Strumigenys are monophyletic is remarkable not only because the morphology of S. nidifex Mann so closely parallels that of the distantly related szalayi-group, or because the morphology of S. basiliska Bolton so closely parallels that of the distantly related biroi-group, but because these two disparate species together with their endemic congeners-even the aberrant S. oasis-all descended from a single common ancestor in the putatively recent past (Lucky and Sarnat 2010, Sarnat and Moreau 2011.

Species identification and delineation
Strumigenys is relatively unique among ant genera with respect to its abundance of morphological characters-particularly hairs, spongiform tissues, mandibles, and sculpture. Despite their minute size and rich taxonomic diversity, species of Strumigenys are thus readily discerned from one another even when few specimens are available for analysis. Initial specimen identification morphospecies designation was conducted as part of Sarnat and Economo (2012). Table 1. Fijian Strumigenys arranged by species name. Species group names and group-complex names to which Bolton (2000) assigned Fijian Strumigenys are listed. Species assigned by Bolton (2000) to Pyramica are also noted  Bolton's (2000) authoritative global revision of Strumigenys was used as the primary identification reference together with examination of type material for all available Fijian endemic Strumigenys. Specimens which could not be identified using the aforementioned references were compared with invasive and tramp Strumigenys before publishing them as morphospecies in Sarnat and Economo (2012). The species concepts presented here are also supported by rigorous phylogenetic analysis of genome-wide SNP markers (Liu et al. in review) that includes 18 of the putative 23.

Micro-CT scanning
We captured X-ray microtomographic scans of 15 Strumigenys specimens representing all species endemic to Fiji for which suitable material was available. The specimens were left attached to their paper point, which was clamped to a holding stage. Scan settings were selected according to yield optimum scan quality and primarily follow Hita Garcia et al. (2017a) and Hita Garcia et al. (2017b). In contrast to the former study, we performed only full body scans and refrained from including standardized scans of head, mesosoma, and metasoma. All micro-CT scans were performed using a Zeiss Xradia 510 Versa 3D X-ray microscope operated with the Zeiss Scout-and-Scan Control System software (version 11.1.6411.17883). Specimen data and scanning parameters are provided in Table 2.

Virtual reconstruction and postprocessing of raw data
Three-dimensional reconstructions of the resulting scan projection data were generated using the Zeiss Scout-and-Scan Control System Reconstructor (version 11.1.6411.17883) and saved in DICOM file format. Post-processing of DICOM raw data was performed with Amira software (version 6.2). Virtual examinations of 3D surface models were performed by using either the 'volren' or 'volume rendering' functions. Desired volume renderings were generated by adjusting color space range to a minimum to ensure the exterior surface of specimens remained visible at the highest available quality. Three-dimensional models were rotated and manipulated to allow a complete virtual examination of the scanned specimens. Images of shaded surface display volume renderings were made with the 'snapshot' function at the maximum resolution (approximately 1900 by 893 pixels).

Three-dimensional model development and optimization for augmented reality applications
Computer generated 3D specimen models The 3D mesh models presented here were generated using micro-CT volumetric data. Each model is composed of large sets of connected vertices and faces (polygons) that can be rendered or streamed in real time. The tradeoff between detail and performance is inherent to 3D modeling (Franco et al. 2004). Increasing model detail decreases model performance: detail is measured by the number of polygons (or vertices) in the model, performance is measured by the processing time needed to render the model Micro-CT is an effective method for capturing internal structures and reconstructing surface volumes. However, CT volumes do not capture surface appearance such as colors and textures. To create specimen models with both morphologically accurate surface volumes and visually accurate colors and textures, we mapped 2D specimen photographs onto the CT surface volume using the application Zbrush.
We developed two versions of 3D specimen models for each of the newly described Strumigenys species: maximum detail and optimized. Insect Systematics and Diversity, 2019, Vol. 3, No. 6 The maximum detail models were generated to preserve as much of the original specimen surface topology as data allowed. All polygons are preserved from the original micro-CT scans described in the preceding section. The target audiences of the maximum detail models are colleagues interested in using the models for scientific research. The optimized models were generated to preserve the maximum level of detail that can be smoothly rendered by an iPhone 6s or equivalent mobile device. In order to determine a suitable tradeoff of detail versus performance, we created four additional models of varying polygon numbers (1m, 500k, 100k, 14k) derived from the maximum quality model (8.1m polygons) of the Strumigenys avatar holotype (CASENT0185902). Of the optimization trials, the 500k polygon model was the highest-detail model that reliably rendered using the augmented reality function in the Sketchfab app with an iPhone 6s (the 1m and 8.1m polygon models proved too large for rendering). Based on the optimization trial results for S. avatar, we optimized the models of the additional five new species to 500k polygons.
The first step of the optimization process was to use the Zbrush digital sculpting application to remove as many noninformative polygons from the model as possible, specifically polygons representing the paper point and glue used for mounting the ant specimen. The number of polygons was reduced using the DynaMesh tool within the Zbrush application. Rather than distribute polygons equally across the entire mesh model, priority was given to parts of the specimen that are morphologically complex, such as the head. The mesh was prepared for texture mapping using the ZRemesher tool of Zbrush which projects a 2D image to a 3D model surface. The model was then imported into the application 3Ds Max and unwrapped (separated and unfolded) for projecting the texture. The images used for texture were the three standard 2D photographs of each respective specimen. The Zbrush application was used for painting and applying the 2D photographs onto the 3D model. The final step in the process was to export the model to FBX and to upload together with the MTL file and texture files to Sketchfab.

Map model
The goal of three-dimensional modeling of geographic terrain is to displace a textured 3D planar mesh vertically using the heightmap, smooth the mesh, simplify the mesh, and export the mesh as a 3D model. Landsat 8 imagery of the Fiji Islands pansharpened to 15 meters was used to create a natural color texture overlay for a 3D elevation model. Multiple Landsat 8 images were color matched and mosaicked in ENVI 5.1 and retouched and further color matched in Adobe Photoshop to create a seamless cloud-free landscape. Date ranges for the imagery used are from 22 January 2014 to 20 March 2018 and were chosen from among 1,440 different images of mixed seasons. 3D map elevation data were derived from the Shuttle Radar Topography Mission (SRTM) 1 arc-sec global dataset. Voids present in the SRTM dataset were filled with the void-filled SRTM 3-arc-sec product. Aberrations and spikes in the SRTM data were smoothed using the 'Spot Healing Brush' in Adobe Photoshop. The 3D elevation model was made using Blender 2.79b (www.blender.org). The modified SRTM elevation raster, Landsat 8 imagery, and species locations were imported to Blender using the BlenderGIS plugin (https:// github.com/domlysz/BlenderGIS). The SRTM elevation raster was converted to a mesh using the 'Displace' modifier in Blender with a strength of zero applied to a mesh of 19.2 million vertices. The final mesh was decimated and smoothed to simplify the geometry and then combined with a normal map generated from the high-density mesh to recover detail and remain performant. Ocean waves were generated using Blender's 'Ocean' modifier on a separate surface and merged with the normal map for elevation dataw.
Finally, the models were added onto the Sketchfab (Sketchfab, New York City, New York), a 3D content publishing platform to provide a website interface for interactive manipulation of the model and future presentation and annotation. Sketchfab is a platform to share and discover 3D, virtual reality, and augmented reality content. All models are available for viewing and manipulating at the following URL [https://sketchfab.com/arilab/collections/ strumigenys-species-from-fiji].

Augmented reality app development
We designed the mobile app 'Insects3D' for interacting with threedimensional models of taxonomic content in augmented reality. The experience was developed in Unity 2018.2.13f1 using the Vuforia 7.2.23 Unity package, which enabled AR in the application. Extended tracking, which enabled ground detection system and improved tracking stability, was implemented using Apple ARKit. The experience was designed for Apple iPhones and Apple iPads with AR-capable processing power (6S and above for iPhone).

Data availability
All specimens used in this study have been databased and the data are freely accessible on AntWeb (http://www.antweb.org). Each specimen can be traced by a unique specimen identifier attached to its pin. The cybertype/virtual datasets provided in this study consist of the full micro-CT original volumetric datasets (in DICOM format). All data have been archived and are freely available from the Dryad Digital Repository (https://doi.org/10.5061/dryad.1f9d55b). In addition to the cybertype data at Dryad, we also provide freely accessible 3D surface models of all treated species on Sketchfab in the 'Strumigenys species from Fiji' collection <https://skfb.ly/6FnYo>.

Study specimens
The material examined in this study was collected from 2002 to 2007, and includes specimens collected as part of the Fiji Terrestrial Arthropod Survey (Evenhuis and Bickel 2005) and other collections made by the authors . The ant specimens were collected and stored in ethanol before they were dry mounted on paper tips and insect pins and are currently deposited in the ant collection in OIST, Okinawa, Japan. The holotype material designated here will be deposited in the BPBM. Paratypes will also be deposited in MCZC and USNM. Readers are referred to the relevant species accounts in Sarnat and Economo (2012) for a comprehensive list of all material examined. All specimens and their associated data can be accessed by using the advanced search option in Antweb.org. Additional images along with additional specimen, collection and locality data for all species treated here are available on Antweb.org.

Standard measurements and indices
Measurements and terminology follow Bolton (2000). All measurements are expressed in millimeters. Measurements presented for all previously described species, with the exception of S. trauma, are taken from Bolton (2000). Measurements presented for S. trauma include original data taken from Fijian specimens.

Results and Discussion
Three-dimensional model development and optimization for augmented reality applications Insects3D: an augmented reality app for visualizing specimen models Insects3D is an iOS compatible app designed as a proof-of-concept solution for integrating augmented reality content with systematic biology. Insects3D is available as a free download from the Apple App Store <https://apps.apple.com/us/app/insects3d/id1451203549>. A short video demonstrating the features and functionality of Insects3D is available from the online version of this article (Supp. Vid. S2) and on YouTube <https://youtu.be/uSy1M7zPjIY>.
The Insects3D app allows users to visualize 3D specimen models of the six new Strumigenys species described here using two different modes (Fig. 1). In 3D mode, the models display on-screen and can be rotated along three axes using touch gestures. In AR mode, the models are anchored either to a visual marker or to a user-selected surface. The computer-generated models display on the device's camera screen and behave as if they were fixed objects in the room. The user observes the models from different angles either by keeping the mobile device stationary and moving the visual marker, or by keeping the marker stationary and moving the mobile device.
Users select which species to visualize using the taxon selector dropdown menu and toggle between specimen model and map model by tapping the specimen/map icon. The following features are available in both 3D and AR mode: a) pinch-to-resize [scales size of specimen and map model], b) spin [rotates specimen model 360° on vertical axis], c) texture slider [increases/decreases opacity of specimen model texture (e.g., surface color)].
The app recognizes two classes of markers: universal markers and species-specific markers. Visual markers are typically graphic symbols that can be recognized with machine vision and accessed using cameras in mobile devices (Zhou et al. 2008, Costanza and Huang 2009, Alakärppä et al. 2017. The universal marker (Supp. Fig. 1 [online only]) is a vector-based illustration of a Strumigenys head in face-view. Once scanned with the device camera in AR mode of the app, the universal marker allows users to select across all six specimen models. The species-specific markers are the plates of shaded surface display volume renderings presented for each of the six new species presented here. Scanning micro-CT plates labeled 'AR marker' with the Insects3D app in AR mode will trigger the display of the respective specimen model.

Texture mapping
After evaluating our texture mapping results, we suggest several modifications to improve future methods. With respect to texture mapping, our primary objective in this study was to determine whether adequate results could be achieved using only the three standard 2D specimen photographs (head, profile, dorsal). Although the addition of color to the mesh models presented here may make them more engaging for a nonscientific audience, they are not satisfactory for scientific research applications. Quality would most certainly increase to the extent photographs from additional angles are incorporated. Constraining our sources to the three standard images limited the texture quality of the models. Much of the surface detail preserved in the 500k polygon micro-CT model (e.g., individual ommatidia) was masked by low-resolution texture imagery. As result, comparable visual quality could be achieved by using lower polycount and faster performing mesh models.
Upon reviewing the nascent literature, we propose 360° imagebased techniques, such as those used in photogrammetry, are more economical and will arguably yield higher quality texture resultsas measured by verisimilitude and processing requirements-than those achieved by our use of only three standard images mapped onto CT-based mesh models. As caveat, CT-based techniques are superior to image-based techniques for capturing internal and occluded structures, and new methods for combining the two are being developed with results more impressive than those presented here (Ijiri et al. 2018).

Opportunities and challenges for AR enhanced biodiversity science
With respect to the study presented here, the current state of AR technology suggests its value to biodiversity education outstrips its value to taxonomic research. The models that worked best on our mobile devices with respect to loading time and rendering speed were the ones with the lowest visual quality-and hence, most limited taxonomic value. And even if the highest visual quality models were loaded quickly and rendered smoothly, using a mobile device for model viewing is cumbersome and not necessarily conducive to a taxonomic description workflow that already includes microscopes, keyboards, and computer screens.
While AR added limited value to the taxonomic study presented here, it is worth discussing the potential of AR technology as it relates to specimen-based research. A future-albeit a distant oneis imagined in which a researcher surrounded by museum drawers accesses specimen data in AR using a mobile device. Consider, for example, a specimen AR app similar to the one presented here is installed on your phone. You pull the Strumigenys avatar holotype out from the drawer, place it in an empty unit tray or on a stage, and use your app to scan the printed 'CASENT0185902' unique specimen identifier label. Without needing computer or microscope, you examine from all angles a 3D virtual model using your phone screen. You view a 3D map of the collection locality to ascertain biogeographic factors. If the collection site was captured with 360° photo or video, you point your phone up to view the type locality's canopy cover, down for ground cover and substrate, straight ahead and all around for vegetation composition.
In contrast to AR, the micro-CT technology used to generate virtual specimen models added discernable value to our taxonomic workflows. For example, incorporating 3D models into our species description and diagnostic key workflows decreased the time and risk of handling type specimens. Unlike our phones, which were unable to smoothly render high polycount mesh models, our personal computers had no difficulty processing the highest quality scans. There were numerous occasions whereupon the character states such as shape and sculpture were rendered clearly enough in the 3D specimen models as to be used for species description without needing to physically handle the type specimens. Likewise, viewing multiple models simultaneously was useful for designing the diagnostic key. We found the 3D models to be preferable to 2D photographs for examining shape and sculpture, but they were inadequate for examining pilosity-a result also discussed by Hita Garcia et al. (2017b). Although we advocate for increasing the use of 3D technologies in taxonomic research, we caution that its inclusion-as with molecular data-should not be prerequisite for the publication of species descriptions. In our introduction, we argued that new imaging technologies have increased the rate and clarity of species descriptions. While we believe this claim true for focus-stacking technologies used for 2D specimen photography, it is less applicable to 3D imagining-at least when microtomographic methods are used. With respect to taxonomic research, 3D microtomography is arguably more similar to molecular data. Both add significant value to taxonomy but also significant investments in time, training, and treasure. Given the enormous numbers of undescribed species relative to the few numbers of taxonomists and slow publication rate, adding additional constraints is not necessarily a winning strategy for addressing the taxonomic impediment.
Whereas the value of AR technology to taxonomic research is disputable in its current state, AR has demonstrated broad value in educational contexts (Wu et al. 2013, Akçayır and Akçayır 2017, Chen et al. 2017)-and biodiversity education specifically (White et al. 2006, Yeh et al. 2006, Barry et al. 2012, Chiang et al. 2014, Seltmann et al. 2017. The technology already exists for taxonomists to upload 3D specimen models to online databases, and for end users to view models on their mobile devices using free iOS and Android apps such as Sketchfab, Augment, and similar platforms. Student posters at scientific conferences, curated exhibits at natural history museums, textbooks in classrooms could all use AR to make taxonomic subjects available to large audiences. Being able to interact with large-scale, 3D and potentially natural-color models using one's own phone or tablet is a more immersive experience than viewing a small, static, 2D photograph of the same specimen. In many ways, interacting with specimen models using AR technologies offers a compelling alternative to microscopes. Microscopes are expensive, limited in availability, and difficult to use without prior training. With AR, an experience similar to viewing minute invertebrates on a rotating stage under strong magnification can be achieved using the phone in one's pocket.  (Bolton) S. tumida Bolton

Diagnosis of Strumigenys worker caste among Fijian ants
Small to minute. Head shape triangular. Antennae 6-segmented. Antennal club 2-segmented. Eyes located on lower margin of antennal scrobes. Mandibles either linear and tipped with apical fork or triangular and armed with numerous denticles. Propodeum armed with spines or teeth. Waist 2-segmented. Spongiform tissue attached to at least some portion of waist. Hairs appearing flagellate or spatulate on at least some portion of head or body. Freely projecting filamentous hairs present along entire lateral margin of head from posterolateral lobe to antennal insertions (Fig. 6I, Fig. 7A). Cephalic and pronotal surfaces smooth with large and deep irregular pits (Fig. 7A, Fig. 9B). First gastral segment lacking any sculpturing the entire length of the tergite (Fig. 9B)  Freely projecting filamentous hairs lacking between the apicoscrobal hair and eye level (Fig. 6J, Fig. 7B). Cephalic and pronotal surfaces reticulate-punctate, lacking large irregular pits (Fig. 7E, Fig. 9J). First gastral segment with basigastral costulae distinctly longer than the length of the postpetiolar disc (Fig. 9J)  lamella (Fig. 6W). Dense tuft of white filamentous hairs arising from the lateral promesonotal border above the procoxae (Fig.  10E). Dorsum of mesosoma with abundant long white erect hairs (Fig. 10E) (Fig. 7D). Dense tuft of white filamentous hairs lacking from the lateral promesonotal border above the procoxae (Fig. 9G). With mesosoma in profile the propodeal declivity lacking a conspicuous spongiform lamella (Fig. 6V). Dorsum of mesosoma lacking abundant long white erect hairs (Fig. 9G) (Fig. 6S) (Fig. 10R). Disc of postpetiole longitudinally sulcate, sulci narrower and finer than on pronotum (Fig. 10R). Cephalic dorsum coarsely longitudinally rugose (Fig. 8J). Ventral spongiform curtain of petiole narrow, at maximum only a fraction the depth of the peduncle (Fig. 10Q)  Hairs on dorsal surface of head, mesosoma and metasoma long, fine and erect (Fig. 9W). In full face view eyes visible, not shielded by lateral head margins (Fig. 7L)

Species accounts
S. anorak n. sp.
Worker Strumigenys anorak is a relatively large and highly distinctive rich reddish brown species with abundant flagellate and filiform hairs on its dorsal surfaces, a unique sculpture characterized by a smooth integument interrupted by deep irregularly sized and shaped pits, and the presence of a broad and conspicuous propodeal lamella. Additional characters for separating S. anorak from similar Fijian species are given in the notes for S. daithma. The species is represented by three specimens, two from Gau and one from Viti Levu, all between 400 and 475 meters and collected from extracted leaf litter.
Etymology: Anorak refers to the online avatar of James Donovan Halliday, creator of the virtual reality world OASIS, in the fictional work Ready Player One (Cline 2011). The name is a noun in apposition and thus invariable. S. artemis n. sp.
( Fig. 7B; Fig. 9C, D; Fig. 12; Fig. 26  width. Apicoscrobal hair short and simple, weakly projecting laterally but not filiform or flagellate. Cephalic dorsum uniformly reticulate-punctate. Ground pilosity of cephalic dorsum short, simple, strongly curved. Pronotal humeral hairs short and simple. Promesonotal dorsum with short curved ground pilosity; lacking long filiform or flagellate hairs. Promesonotal dorsum and sides longitudinally striate to reticulate-punctate. Propodeal dorsum uniformly reticulate-punctate. Mesopleuron, metapleuron and side of propodeum mostly smooth. Propodeal tooth short, narrowly triangular. Lamellae attending the propodeal spines vary from thin and parallel to the declivity, to wider and not paralleling the declivity. Legs entirely lacking projecting filiform to flagellate hairs. Petiolar node in profile evenly convex with similar anterior and posterior faces; lateral spongiform lobe small; restricted to posterior margin of node. Dorsum of petiole strongly reticulate-punctate. Postpetiolar disc weakly reticulate-punctate. Ventral lobe of postpetiole spongiform. First gastral tergite with erect flagellate hairs and long ground pilosity. Basigastral sculpturing is conspicuously longer than the length of the postpetiolar disc.
Strumigenys artemis is a small, dull yellowish-brown species with strongly reduced pilosity. The apicoscrobal and humeral hairs are short and simple, and the legs lack erect hairs entirely. The Fijian species most resembling S. artemis are S. jepsoni and S. mailei. Whereas S. artemis and S. mailei have relatively short and simple apicoscrobal and humeral hairs, those of S. jepsoni are long and flagellate. Strumigenys artemis is distinguished from  hairs on the legs, and the differences in sculpture and pilosity are not discrete enough to warrant separation of species. Strumigenys artemis is widespread, occurring even on the smaller islands in the archipelago.
Etymology: Artemis is the Latinized version of Art3mis, a famous gunter in the fictional work Ready Player One (Cline 2011). Artemis is also the Greek goddess of the hunt and is an apt name for a Strumigenys species. The name is a noun in apposition and thus invariable.    reddish-brown with yellowish-brown appendages. Mandibles long and linear. Apical fork composed of two spiniform teeth and a single intercalary denticle. Single stoutly spiniform preapical tooth present close to the apicodorsal tooth. Cephalic dorsum uniformly reticulate-punctate; with five pairs of erect simple hairs on posterior margin and one pair close to the highest point of vertex. Antennal scapes very long. In full-face view, sides of head immediately in front of the eye with an abrupt and very conspicuous indentation. Vertex of head raised with dorsolateral margin mesad of eye formed into a knobby protuberance. Region of head between vertex and posterolateral lobes depressed. Scrobe absent behind level of eye. Pronotal humeral hairs simple, short and stiff. Two additional pairs of simple erect hairs present on promesonotum. Postpetiole with two pairs of erect hairs, first gastral segment with five pairs. Legs entirely lacking projecting hairs. Mesosoma, petiole, and postpetiole uniformly and finely reticulate-punctate on all surfaces. Propodeal teeth free; margin of declivity entirely lacking even a thin lamella. Petiole node in dorsal view conspicuously longer than broad. Spongiform appendages of waist segments reduced. On petiole present as a thin, narrow curtain subtending the ventral margin and posterodorsal margin. Entire first tergite and sternite of gaster finely striate-punctate.
Strumigenys avatar is a large, long-limbed, dark reddish-brown species with a distinctive head shape. The only other Fijian species resembling S. avatar is its close and better-known relative S. nidifex. The two can be easily distinguished by the first gaster tergite and sternite. In S. avatar, these are entirely striate-punctate. In S. nidifex, sculpture is restricted to short basigastral costulae on the tergite. Additional discussion of these two species is given under the notes of S. nidifex. Strumigenys avatar is known only from a single collection in the Nadarivatu area (Viti Levu), which is also the type locality of S. nidifex. The two are sympatric, which, together with the clear morphological differences, validates the distinction of two separate species.
Etymology: Avatar refers to the three-dimensional representation of OASIS users in the fictional work Ready Player One (Cline 2011). The name is a noun in apposition and thus invariable.
S. basiliska Bolton ( Fig. 7D; Fig. 9G, H; Fig. 14, Fig. 26  (ANIC, examined). PARATYPEs: workers (ANIC, examined); workers (BMNH, examined). In Fiji (Sarnat and Economo 2012: 127, pl. 121 be recognized by the highly polished dark reddish-brown color, reduced pilosity, short arcuate mandibles, and lack of propodeal lamellae. Although morphological variation of S. basiliska across the archipelago is largely congruent with geographic patterns , genetic analysis suggests that these differences represent intraspecific variation across populations (Liu et al. in prep.). Bolton tentatively placed S. basiliska in the biroi group but admitted that the Fijian species is so aberrant that the resemblance might be the result of convergence. Specimens collected from New Guinea and housed at the Los Angeles County Museum of Natural History were misidentified by R. Snelling as S. basiliska but belong instead to a putatively undescribed member of the S. biroi species group (D. Booher, pers. comm.). Strumigenys basiliska is widespread throughout the inner islands of the archipelago, though no records from Taveuni or Kadavu are known.
S. chernovi Dlussky ( Fig. 7E; Fig. 9I, J; Fig. 15, Fig. 26  Strumigenys chernovi belongs to a group of Fijian longmandible endemics with filiform to flagellate hairs on the pronotal humeri and the basitarsus. This group also includes S. daithma,  . anorak, S. ekasura, S. jepsoni, S. panaulax, S. scelesta, S. gunter, and S. parzival. The tramp ant Strumigenys godeffroyi is superficially similar to this group, but is from an evolutionarily distinct lineage distantly related to these Fijian endemics and can be separated by the presence of sculpture on the mesopleuron. Within the group, Strumigenys chernovi is most similar to other species which have only one or two filiform to flagellate hairs projecting from the dorsolateral head margin; namely S. jepsoni, S. panaulax, S. scelesta, S. gunter, and S. parzival. Of these, S. gunter is the only species with a single eye facet. Strumigenys panaulax and S. parzival are the only species with gastral sculpture that extends the entire length of the first tergite. Strumigenys chernovi is very similar to S. jepsoni but can be separated by the dorsum of the petiole and postpetiole which is sculptured in the former but glassy smooth in the latter. Additionally, S. chernovi has two projecting filamentous hairs on the cephalic dorsolateral margin (one apicoscrobal and one at eye length), whereas S. jepsoni has only one (apicoscrobal).

S
Strumigenys chernovi is widespread, recorded from most of the major islands with the exceptions of Kadavu and Taveuni.
S. daithma Bolton ( Fig. 7F; Fig. 9K, L; Fig. 26    Additionally, it appears that S. daithma is darker are more roughly sculptured than S. ekasura. S. ekasura Bolton ( Fig. 7G; Fig. 9M, N; Fig. 16; Fig. 26  rainforest, sieved litter (G. Monteith). HOLOTYPE: worker (ANIC, not examined). In Fiji (Sarnat and Economo 2012: 129, pl. 124 is long-mandible species characterized by abundant free-stranding flagellate pilosity on all dorsal surfaces, a sculptured postpetiolar disc, conspicuous basigastral pilosity, and the lack of a propodeal lamella. The species was originally ascribed by Bolton (2000) to the smythiesii-species group, but belongs instead to the single in situ radiation of Fijian Strumigenys (Booher and Economo, unpublished data). Strumigenys ekasura is most similar in appearance to several other Fijian species with abundant filiform and flagellate hairs on the head and mesosoma-namely S. anorak, S. daithma, and to a lesser extent S. chernovi. In addition to the characters given in the key, we refer readers to the notes given under the latter two species accounts for discussion on how to separate S. ekasura from similar Fijian Strumigenys. The species is widespread and is recorded from most of the major islands with the exception of Taveuni and Ovalau.   Model 1. Strumigenys anorak (CASENT0186900, holotype) presented as a computer generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab. com/3d-models/9bdd4f1426a44a27996289172a2bbe33 Model 2. Strumigenys artemis (CASENT0186982) presented as a computer generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab.com/3d-mode ls/616f07097a7e4b4ca5ae38e6d14ff6c5 Model 3. Strumigenys avatar (CASENT0185902, holotype) presented as a computer-generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab.com/3d-models/b258462cc47c44d48e5b9edf8b 50e632 Model 4. Strumigenys gunter (CASENT0184984, holotype) presented as a computer-generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab. com/3d-models/2e5ace8bb36843b19a41b0c9f7f2b842 Model 5. Strumigenys oasis (CASENT0185751, holotype) presented as a computer-generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab. com/3d-models/002454768d2a4409b922b09222fc80a1 Model 6. Strumigenys parzival (CASENT0186960, holotype) presented as a computer-generated 3D mesh model optimized for augmented reality. Volumetric surfaces rendered from micro-ct data and texture mapped from standard specimen photographs. An interactive version of this model is available in the HTML version of this article online and at https://sketchfab. com/3d-models/2d608f095a1d4daea3ba34e0cae83255 S. frivola in the rofocala complex as a matter of convenience because it lacks erect flagellate hairs on the dorsal surface of the hind basitarsus, but suggested (correctly) that it might be more closely related to other Fijian endemics. Strumigenys artemis and S. mailei are similar in appearance to S. frivola and also lack flagellate basitarsal hairs. Whereas the apicoscrobal and humeral hairs of S. frivola are flagellate, those of the other two species are simple. Furthermore, the only erect hairs on the pronotal dorsum of S. frivola are the humeral hairs, whereas the other two species have pairs of erect hairs on their pronotal dorsa in addition to the humeral pair. Strumigenys frivola is apparently quite rare, as it is known only from the type locality at Nadarivatu (Viti Levu), a nest collection from nearby Mt. Tomanivi, and a fogging sample at the nearby Monasavu Dam area.
S. godeffroyi Mayr ( Fig. 7I; Fig. 9Q, R; Fig. 27) godeffroyi. Strumigenys godeffroyi Mayr 1866 88 : 516; worker described. Type locality: SAMOA [not examined]. Queen described (Mayr 1887: 569). Karyotyped (Imai et al. 1984: 68). In global revision (Bolton 2000: 791). In Fiji (Sarnat and Economo 2012: 130, pl. 126). 28. Strumigenys godeffroyi is a reddish brown, long-mandible, strongly pilose species with many pairs of long flagellate hairs on the mesosoma and metasoma in addition to a dense ground pilosity consisting of semidecumbant hairs on the cephalic and mesosomal dorsal surfaces. The apicoscrobal, humeral, and basitarsal hairs are all long a flagellate. The propodeal lamella is extensive and covers the propodeal spine. Strumigenys godeffroyi is superficially similar to other Fijian Strumigenys species with extensive filiform and flagellate pilosity, namely S. daithma, S. anorak, and S. ekasura. Whereas the mesopleuron of S. godeffroyi is reticulate-punctate, that of the aforementioned species is polished smooth. Moreover, the other species all have multiple pairs of filiform to flagellate hairs projecting from the dorsolateral cephalic margin between the apicoscrobal hair and the eye, while S. godeffroyi has only the projecting apicoscrobal hairs. The propodeal lamella is strongly produced in S. godeffroyi, appearing quite thick in dorsal view. Strumigenys daithma and S. ekasura lack propodeal lamellae entirely, and those of S. anorak are much thinner with the propodeal spines clearly visible. Although likely native to Southeastern Asia, Strumigenys godeffroyi did not descend from the ancestor of the Fijian Strumigenys radiation. It is a successful tramp species that has spread across the Pacific and has been recorded from most of Fiji's major islands.
Strumigenys gunter is a small shiny pale-yellow species with small eyes of one to several facets, abundant long flexous hairs on metasomal dorsum, and shorter subdecumbent hairs on the promesonotum. It morphologically similar to a cluster of species related to S. chernovi, but is immediately distinguished by the smaller eyes. Additional diagnostic notes are given under S. chernovi. Strumigenys gunter is only known from three worker specimens collected on Gau and Koro.
Etymology: Gunter is a contraction of 'egg' and 'hunter' in the fictional work Ready Player One (Cline 2011) and refers to particular users of the virtual reality world OASIS. The name is a noun in apposition and thus invariable. Syntypes: 2 workers (MCZC type no. 21099, examined); 4 workers (USNM, examined). In global revision (Bolton 2000: 809). In Fiji (Sarnat and Economo 2012: 130, pl. 127).

S. jepsoni
Worker. Measurements (n = 7): TL 2. . Strumigenys jepsoni is a small, long-mandible, reddish-brown species with short pilosity and strongly shining dorsal surfaces of the petiole and postpetiole. The apicoscrobal and pronotal humeral hairs are relative short and stiff, the basitarsal hair is flagellate, and the propodeal lamella are broad and conspicuous in profile. Strumigenys is most similar to S. gunter and S. scelesta, as all three species have flagellate basitarsal hairs, and no laterally projecting hairs on the cephalic dorsum save the apicoscrobal pair. Whereas S. jepsoni and S. gunter have at least one pair of erect hairs on the pronotal dorsum in addition to the humeral hairs, S. scelesta has none. Strumigenys jepsoni is most reliably separated from S. gunter by its larger eye.
Strumigenys jepsoni was named after Mr. F. P. Jepson, Entomologist of Fiji. The species was not collected during the major 2002-2008 surveys of Fijian ants . The only two records of the species are both from Vanua Levu. Wilson & Taylor (Fig. 7L;Fig. 9W,X;Fig. 19;Fig. 27) mailei. Strumigenys mailei Wilson & Taylor 1967: 38, Fig. 28 (Bolton 2000: 823). In Fiji (Sarnat and Economo 2012: 130, pl. 128  Strumigenys membranifera is a short mandible species with a strongly convex cephalic dorsum that bears a single pair of standing hairs. It can be separated from Fiji's native short mandible species, S. trauma, by the lack of pronotal humeral hairs and the smooth dorsal surfaces of its mesosoma and petiole. Wilson and Taylor (1967) offered the following discussion of S. membranifera, 'Brown (1949) states that T. membranifera [= S. membranifera] is probably of African origin. It has been spread by human commerce through a large part of the tropics and warm temperate zones, including such diverse areas as the Fiji Is., eastern China, West Indies and southeastern United States. The species has an ecological amplitude unusual for a dacetine, nesting in major habitats from dense woodland to dry, open cultivated fields'. Wilson (1954) described the feeding behavior of the workers as being predaceous on a wide variety of small, soft-bodied arthropods. In Fiji, the species is relatively rare, and during the recent surveys  was represented by a single collection of specimens from a litter sample taken at Rokosalase (Vanua Levu). Several older collections from Fiji were also recorded from museums.  Fig. 23; worker, queen, male described. Type locality: FIJI, Viti Levu, Nadarivatu (W. M. Mann). Syntypes: 7 workers, 2 queens (MCZC type no. 8710, examined); 1 worker, 4 queens, 1 male (USNM, examined). Larva described (Wheeler and Wheeler 1955: 140). Discussed (Brown 1954). In revision of szalayi group (Brown 1971: 81); in global revision (Bolton 2000: 905). In Fiji (Sarnat and Economo 2012: 131;pl. 129).

S. nidifex
Note: Specimens from the nontype locality of Buka Levu (USNM), Waiyanitu (MCZC), and Veisari (MCZC) bear red cotype labels but are not true syntypes (Sarnat and Economo 2012: 131). Worker. Measurements (n = 10): TL 4.7-5.1, HL 1. . Strumigenys nidifex is one of the most conspicuous Strumigenys of the Fijian fauna, and among the largest Strumigenys on the planet. The species has a distinctively broad head that is impressed posterior to the vertex and bears a preocular impression on the ventrolateral margin of the head. All surfaces of the head, mesosoma, waist, and coxae are reticulate-punctate. The nearest relative to S. nidifex is Strumigenys avatar. The gaster of the former is sculptured basally, but is otherwise strongly polished and shiny. The gaster of the latter is strongly punctate-striate the entire length of the first segment. The males of the two differ, with those of S. nidifex being larger with a distinctly elongated head, while the male of Strumigenys avatar is smaller with a much rounder head. The queen of Strumigenys avatar is also distinctly smaller, especially with regard to the mesonotum. However, the series of S. nidifex from Koro are all smaller, and the queens of that series are more similar to those of Strumigenys avatar than to those of its conspecifics on other islands, with the caveat that its gaster is polished and shiny. Both species occur sympatrically in the Nadarivatu area. The only other species in Fiji with a preocular notch is S. rogeri, which is easily separated by its significantly smaller size, yellow brown color, and mandible with two preapical teeth. The other large Strumigenys in Fiji all lack the preocular impression.
Strumigenys nidifex was originally assigned to the szalayi group by Brown (1971), but recent molecular analysis suggests instead that it is a member of the in situ Fijian radiation (Booher and Economo, unpublished data). Mann (1921) discovered colonies containing upwards of 100 individuals and noted that the workers build thin walls of mud throughout the nest to separate small chambers. E.O. Wilson collected a colony from Viti Levu during his expedition to Fiji and sent it back to Brown's laboratory in the United States. Brown (1971) reported that the colony of 70-80 workers and several dealates was kept for 2 yr. The colony was easy to keep and produced broods of males and queens three times in 2 yr. The workers captured and fed to their larvae a wide variety of small arthropods, including mosquitoes, Drosophila, mites, aphids, beetles, blattarian nymphs, geophilomorph centipedes, and collembola. Brown also discussed predatory, defensive, and oviposition behavior. Strumigenys nidifex is thus one of the very few native Fijian Strumigenys for which any detailed natural history is known  S. oasis n. sp. (Fig. 8C, D; Fig. 10E, F; Fig. 21; Fig. 27 Head cordate, shield-like, becoming very broad posteriorly. Median of posterior head margin with distinct and deeply excavated circular pit. Mandibles strongly truncated and arcuate; shorter than length of terminal antennal segment. Apical fork comprised of three teeth; apical-most two teeth half the length as the third. In addition to the aforementioned three teeth is the basal-most fourth tooth, equal in length to the third, that is apparently homologous to the preapical tooth of relative species but here located so far distally as to be contiguous with the apical fork. Apicoscrobal hair thing stiff and straight. Ground pilosity of cephalic dorsum composed of short and appressed weakly spatulate hairs. Clypeal shield distinct and covered by closely spaced appressed spatulate hairs. Antennal scapes proportionately short . Pronotal humeral hairs long, straight, and stiff. Surface of entire body strongly polished, entirely lacking sculpture except for short basigastral costulae. Dense tuft of white filamentous hairs arising from the lateral promesonotal border above the procoxae. Dorsal surfaces of mesosoma and metasoma with abundant long, stiff, erect hairs. Legs with abundant hairs similar to those on dorsal surfaces of body but entirely lacking flagellate hairs. Propodeal tooth short, broadly triangular. Propodeal lamella in profile with strongly convex posterior margin. In dorsal view, petiolar node distinctly broader than long. Ventral lobe of postpetiole large and broad, more lamellate than spongiform. Posterodorsal lobe of postpetiole obliquely costate, similar in pattern to basigastral sculpture. Strumigenys oasis is without doubt the most peculiar representative of the genus in Fiji. The strongly truncated and arcuate mandibles with four spiniform apical teeth are unlike any other Strumigenys in Fiji-and possibly unique across the entire genus. They appear descended from an ancestor with long and linear mandibles rather than one with triangular mandibles armed with denticles. Another feature apparently unique to S. oasis is the circular pit excavated from the middle of the posterior head margin (Fig. 21D). While similar structures are observed in the species of other genera to receive ocelli, this does not appear to be the case for S. oasis. The third most anomalous feature of S. oasis is the dense tuft of white filamentous hairs arising from the lateral promesonotal border above the procoxae. Though homologous invaginations occur in many of the Fijian Strumigenys species, none are so deep or so densely covered in hairs as that of S. oasis. The only Fijian Strumigenys species approaching S. oasis in morphology is S. basiliska. Both are strongly polished and have short and curved mandibles with spiniform teeth, but those of P. basiliska are distinctly longer than those of S. oasis. Additionally, P. basiliska lacks the median pit on the posterior head margin, shield-shaped head, propodeal lamellae, and abundant long, stiff, erect hairs. The only collection of this species is from a leaf litter sample taken at Nabukavesi in southeastern Viti Levu.
Etymology: Oasis (Ontologically Anthropocentric Sensory Immersive Simulation) refers to the virtual reality world featured in the fictional work Ready Player One (Cline 2011). The name is a noun in apposition and thus invariable. S. panaulax Bolton ( Fig. 8E; Fig. 10G, H; Fig. 27 S. parzival n. sp.
( Fig. 8F; Fig. 10I, J; Fig. 22; Fig. 28 Mesopleuron, metapleuron, and side of propodeum polished smooth. Pronotal dorsum with one pair and mesonotum with one to two pairs of erect flagellate hairs; ground pilosity long, curved, and flexous. Dorsal surface of hind tibia with at least one flagellate hair that is similar to that on the basitarsus. Propodeal tooth short, narrowly triangular. Propodeal lamella in profile with a straight to shallowly convex posterior margin. Petiolar node in profile evenly convex with similar anterior and posterior faces; lateral spongiform lobe small; restricted to posterior margin of node. Dorsum of petiole strongly reticulate-punctate. Postpetiolar disc weakly reticulate-punctate. Ventral lobe of postpetiole large, thin, and more lamellate than spongiform. Dorsum of petiolar node rugoreticulate; disc of postpetiole with closely spaced longitudinal costulae. First gastral tergite with closely spaced broad and uniform costulae that extend unbroken from base to apex. First gastral tergite with sparse erect flagellate hairs and long filiform pilosity. Strumigenys parzival is a small dark reddish-brown species with flagellate apicoscrobal, humeral and basitarsal hairs, but is most recognizable by the uniform costulae that extend longitudinally across the entire first gastral tergite. The species is nearly identical to P. panaulax with respect to both pilosity patterns and the gastral sculpture. The two are so similar that Sarnat and Economo (2012) did not recognize S. parzival as a new species distinct from P. panaulax. Subsequent comparison with the type specimen of P. panaulax revealed discrete differences between the two species with respect to pronotal and petiolar sculpture. Whereas the pronotal dorsum and petiolar dorsum of P. panaulax are obliquely costulate-rugulose, those of P. parzival are longitudinally and irregularly rugoreticulate. Both these ants are similar to a cluster of species closely related to S. chernovi, and additional diagnostic notes are listed under the latter. Strumigenys parzival is known only from a single leaf litter collection of two workers on Vanua Levu.
Etymology: Parzival refers to the name of the protagonist's virtual reality avatar in the fictional work Ready Player One (Cline 2011). The name is a noun in apposition and thus invariable. 28. Strumigenys praefecta is a long-mandible, mid-sized dark, reddish-brown species with very short antennal scrobes, simple apicoscrobal hairs, no pronotal humeral hairs, and no flagellate basitarsal hairs. Among long-mandible Fijian Strumigenys, the only other species lacking pronotal humeral hairs is S. sulcata. Whereas S. praefecta is characterized by the same finely reticulate-punctate sculpture present in so many of the Fijian Strumigenys, the deeply rugose-sulcate sculpture of S. sulcata is quite distinct and even occurs on the mesopleuron. Bolton (2000) and Sarnat and Economo (2012) reported morphological variation across populations o S. sulcata in Fiji, but we find no compelling evidence for treating these as separate species.
Worker. Measurements (n = 1). TL 2.3, HL 0.57, HW 0.42, CI 74, MdL 0.21, MI 37, SL 0.32, SI 76, PW 0.25. Strumigenys scelesta is a small, long-mandible, light reddish-brown species with a dense covering of short subdecumbent hairs on all of its dorsal surfaces, a flagellate basitarsal hair, no projecting apicoscrobal or pronotal humeral hairs, and a broad propodeal lamella. The species was described by Mann (1921) from the single holotype which is in rather poor condition. It is therefore difficult to comment on the specialized hairs, which could either be naturally absent or worn off by damage. However, the 2002-2008 survey recovered several specimens that bear close resemblance to S. scelesta. We follow the decision by Sarnat and Economo (2012) to, with reservation, consider those specimens as belonging to S. scelesta. A more thorough discussion of the differences between the specimens in question and the holotype was given in the aforementioned study. Strumigenys scelesta is best diagnosed by the combination of the following three characters: presence of flagellate basitarsal hair, absence of projecting apicoscrobal hair, absence of projecting pronotal humeral hair. No other species of Fijian Strumigenys has all three characters. The specimens considered here to be S. scelesta were collected from the lower elevations of Vanua Levu and Viti Levu.
Worker. Measurements (n = 5). TL 3.6-3.8, HL 0.92-1.00, HW 0.65-0.74, CI 68-74, MdL 0.44-0.48, MI 46-49, SL 0.58-0.64, SI 87-94, PW 0.41-0.47. Strumigenys sulcata is a relatively large, long-mandible, dark reddish-brown species with the dorsal surfaces of the mesosoma and postpetiole deeply sulcate. The species lacks projecting apicoscrobal hairs, pronotal humeral hairs, basitarsal hairs, and propodeal lamellae. The rugae of the dorsum of head and sides of mesosoma are also primarily longitudinal, but less regular and more reticulated. The petiole lacks a distinct node. Instead, the peduncle arches gradually into the posterior margin. The only other long-mandible Fijian Strumigenys that entirely lacks freely projecting hairs is S. praefecta. The two species are easily distinguished from each other by the sculpture, however, with S. sulcata deeply sulcate and rugose and S. praefecta finely reticulate-punctate. Strumigenys sulcata is known from most of the archipelago's major islands, and nests have been found in wet, decaying logs. (Bolton) ( Fig. 8K; Fig. 10S (Sarnat and Economo 2012: 118, pl. 115). = Pyramica sp. FJ02 (Sarnat and Economo 2012: 119, pl. 116) Worker. Measurements (n = 5). TL 1. . Strumigenys trauma is a short-mandible, dark brown species with two pairs of standing cephalic hairs, long stout pronotal humeral hairs, punctate dorsal surfaces of the mesosoma and petiole, and a very broad postpetiolar disc. The only other short-mandible Strumigenys currently known from Fiji is the tramp S. membranifera which is separated from S. trauma by the lack of pronotal humeral hairs and the smooth dorsal surfaces of its mesosoma and petiole. After reviewing the material designated as Pyramica sp. FJ02 (= Strumigenys) by Sarnat and Economo (2012) we decide here to include it in a broader definition of S. trauma. While the specimens in question differ from the type material with respect to larger size, smoother pronotal sculpture, and coarser basigastral sculpture the lack of sympatry between the morphological variants and general weakness of the differences leads us to consider the variation as be populaiton-level rather than heterospecific, though additional sampling or analysis could provide evidence to the contrary. This species was assigned by Bolton (2000) to the capitata group, and is presumed to be closely related to S. charybdis (Indonesia), S. epipola (Samoa), S. phasma (New Guinea), S. tethys (New Guinea) and S. themis (New Guinea). S. tumida Bolton ( Fig. 8L; Fig. 10U, V; Fig. 25; Fig. 28 Strumigenys tumida is a long-mandible, dark brown, strongly sculptured species with freely projecting apicoscrobal and pronotal humeral hairs and no flagellate basitarsal hair. With respect to size and overall shape S. tumida is closest to S. praefecta and S. sulcata, but can be distinguished from those species by the presence of projecting humeral hair, the much broader postpetiole relative to the petiole, distinctly short preapical tooth on the mandible, and extremely swollen postpetiole which is conspicuously twice as broad as the petiole in dorsal view. Strumigenys tumida is known from forest habitats most of Fiji's largest islands except for Kadavu.


CultureLED: A 3D printer-based LED illumination cultivation system for multi-well culture plates

Graphical abstract

Hardware in context
Research on microalgal biotechnology dates back to the 19th century and since then technologies have evolved and improved as innovative production systems such as photobioreactors (PBRs) have been employed to improve the algal biomass throughput per area [1]. In order to achieve a better understanding of these microorganisms and reach their maximum potential of applications and productivity, a vast amount of research of various factors is needed. Due to this, there is a growing need for affordable, flexible and easy to control research systems and protocols. This growing research effort is exemplified by the support of the European commission into research and development of microalgal biotechnology by allocating 40 million euros annually between 2007 and 2017 to microalgae-based ventures [2]. To date, there is a wide variety of cultivation systems and PBR types and designs [3]. Different PBR designs, volumes and shapes, allow different types of applications including cultivation systems and PBRs for microalgae mass commercial research and production, microalgae pure cultivation, and specialized PBRs designed for wastewater treatment, which are less prevalent [4]. Cultivation systems and PBRs for photoautotrophic prokaryotic and eukaryotic microorganisms use light (natural or artificial) as a primary energy source and exist in many forms (e.g., open vs closed, tubular vs panels, vertical vs horizontal) [5]. m À2 s À1 with a continuous white light program. Light intensities were measured using Apogee Quantum meter model MQ -200 (Logan, USA). The light intensity is scaled by a bit range of 0-80 bits, above this range (up to 255) when very high light intensities are needed the system requires additional external power supply to be connected directly to the LEDs. Excess heat generated by the LEDs is removed by two 5 V DC fans controlled by the temperature sensor set value. The initial sensor value which operates the fans is set to 25°Celsius. This value could be modified in its section inside the Arduino INO code.
The CultureLED can be used for a wide range of applications and has several advantages: The light setup can be controlled via programming; it can be modified to support versatile light quality and quantity regimes. System dimensions are: Width: base 108 mm, top 148 mm; Depth: 137 mm; Height: 146 mm.
The 6 well plate can be used to cultivate versatile photoautotrophic prokaryotic and eukaryotic microorganisms and small organisms with different medium or solid substrate requirements (e.g., Agar).
The system is modular, easily assembled, and can be easily printed so it can fit into orbital shakers or shelves at different room temperatures.
The small volume is ideal for performing molecular biology experiments. The compact nature of the design can potentially increase the number of simultaneous trials performed in parallel.

Design files
The models were designed using Autodesk Fusion 360 software (Autodesk, USA).

A1 -Base
The base part holds the entire system. The left, right and back panels (parts A2, A3, and A4, respectively) will be connected to this base with their printed pins.

A2 and A3 -Left and right panels
The panels are connected to the base, back panel, and top panel via their printed pins. These parts include paths for the component's drawers as well as small holes (3.2 mm diameter) to lock the drawers. An array of holes (7.5 mm diameter) allows ventilation and heat exchange as well as safer passing of cables if needed.

A4 -Back panel
The back panel is connected to the base and the side panels. Its aim is to provide support and strength to the structure and stop the drawers from sliding out.

A5 -Top panel
The top panel is sealing the structure from above preventing light from entering and going out from the system. It also strengthens the system's structure. The top panel is connected to the left and right panels throughout its 6 printed pins, 3 to each side panel, and designed with 2 side handles for easy disassembly.

B1 -Drawer
The drawer is a modular part that can hold all the components panels (B parts). The drawer slides in through the grooves of the left and right panel (parts A2 and A3) and can be locked using the locking pins (part C3). The drawer also features four trapezoid entrances for cable access and rearrangements.

B2 -Board panel
The board panel is designed to house the SparkFun RedBoard QWIIC board of the system. It has 4 pins to mount the board. This panel fits inside the drawer (part B1) and it's the first panel from below.

B3 -Fans panel
The fans panel is designed to house two 60 mm X 60 mm DC fans, to dissipate possible heat released during the LED's activity. The panel has small trapezoid paths for cables and 4 top holes that connect to 2 bridge lockers. This panel is sitting on a drawer, and it's the second panel from below.

B4 -LED's panel
The LED's panel is designed to hold six Adafruit NeoPixel Jewel LED units, one below each well of the 6 well plate. The LED units are connected to the panel via screws. Furthermore, the temperature sensor is mounted below via screws. This panel is sitting inside a drawer and located below the 6 well plate. It's the third panel from below.

B5 -6 well panel
This panel is simply designed to hold a 6 well plate, without blocking the emitted light below it. It is compatible with several 6 well plate brands although we used Cellvis 6 Well glass bottom plate with high performance #1.5 cover glass due to its black frame. This panel is sitting on a drawer, and it should be located above the LEDs panel (part B4) and below the top panel (part A5).

C1 -Fans panel locks
These locks are designed to hold the fans to their panel via pins with minimal disturbance to the airflow. Each lock has a small step to route the fan cables.

C2 -LED's panel lid
The lid is designed to cover the LED's panel and protect them and their wiring while providing a better aesthetic look.

C3 -Locking pins
The locking pins are small parts that lock and the drawers to the left and right panels (parts A2 and A3). These pins are designed to be inserted into the small holes in the side panels into the drawers.

D1 + D2 -Remote + Remote's lid
The remote is an additional and external part that is designed to hold two electronic parts: Micro OLED Breakout (Qwiic) and the Qwiic Twist -RGB Rotary Encoder Breakout. This part is connected to the RedBoard via a long Qwiic cable (500 mm) and allows the user to change predefined light programs, control the lighting intensity and display the temperature around the LEDs.

Build instructions
Preassembly safety note: The assembly of this system requires 3D printed parts and their mechanical assembly (sections 5.1-5.4), minimal soldering and connection of the electronic parts (section 5.5) and programming (section 5.6). Take any necessary precautions while working with the 3D printer and solder to prevent short circuits or injury. Take care while working with electricity.
With exception to the above, Part C3 -Locking Pins were printed with the same parameters above but with fill density: 100 % due to their small size.
Stand assembly (parts A1 to A5): The 3D printed parts build instructions are also shown in an animation file (CultureLED_assemblyGuide.MP4) and movie (CultureLED_systemOperation.mp4). The animation file was done using Autodesk Fusion 360 software (Autodesk. USA) and Corel VideoStudio Ultimate 2021 (Corel Corporation, Canada).
Step 1: Place the base panel (Fig. 1A, part A1) on a solid, balanced surface, then take both side panels (Fig. 1A, parts A2 and A3) and connect them using their pins. Make sure that the panels are placed in the right direction, the base panel two horizontal rounded holes should be located in the back of the structure. Apply a little pressure to hold them tighter to the base.
Step 2: Once parts A1, A2, and A3 are assembled in the right direction, connect the back panel (Fig. 1A, part A4) with its pins to the four rounded holes in the back of the assembly (step 1). Please be aware that the smaller holes should be located at the top.
Step 3: Take the top panel (Fig. 1A, part A5) and connect it to the top of the structure using its six printed pins, three connected to each side. Apply a little pressure from all sides to tighten all the parts together and avoid unnecessary spaces as shown in Fig. 1A and Fig. 2A.
Drawers and components assembly (parts B1 to B5): Once section 5.1 is completed, the assembly/stand is ready for the modular drawer including the components that fit in it. Before continuing, make sure to properly connect and solder the electronic parts as shown in Fig. 3. Also, notice that this section requires four printed units of the drawer part ( Fig. 1B and 2B, parts B1) and locking pins ( Fig. 1B and 2B, parts C3).
Step 1: Connect the SparkFun RedBoard Qwiic (Fig. 4A, part 1) to a board panel (Fig. 4A, part B2) using the four mounting holes. The board DC jack and USB connector should be facing forward ( Fig. 4A and Fig. 5A). Insert this assembly into one drawer (Fig. 4A, part B1) and put it aside until the final assembly.
Step 2: Attach two 60 mm Â 60 mm Â 10 mm DC fans where their cables face forward to the fans panel ( Fig. 4B and 5B, part B3). Mount the fans panel locks (Fig. 4B and 5B, part C1) to the fans panel ( Fig. 4B and 5B, part B3) to lock them. Make sure it's well placed over each fan, while the cables run smoothly underneath them, in the dedicated path. Screw the fan power cables to the Qwiic Motor Driver (Fig. 5B, part 3). Insert this assembly into another drawer ( Fig. 4B and 5B, part B1) and slide it to the stand as shown in Fig. 4B.
Step 3: Screw to the bottom of the LED panel ( Fig. 4C and 5C, part B4) a digital temperature sensor -TMP102 (Qwiic) (Fig. 5C, part 5) using M2x6mm plastic, the sensor should be faced up (as shown in Fig. 5C, part 5). Make sure that the TMP 102's Qwiic cable is connected from below. Now, place the soldered Adafruit NeoPixel Jewel LEDs and the attached wires (section 5.5), screw the LEDs using with two M2x6mm for each unit, except LEDs located at position #2 and #4 (in the row) that are close to the sensor, each should be connected with only one screw (Fig. 5C, parts B4 and 6). Put the LED's panel lid (Fig. 5C, part C2) on the LED's panel (Fig. 5C, part B4) and make sure it is not obscuring the LEDs. Insert this assembly into another drawer (Fig. 5C, part B1) and slide it into the stand as shown in Fig. 4C. The wires should face outside the drawer and later will be connected to the RedBoard (section 5.5).
Step 4: Attach a 6 well plate (Fig. 4D, part 4 and Fig. 5D, part 7) with microalgae culture to the 6 well panel ( Fig. 4D and 5D, part B5) and gently tighten and align it where the 4 pins are supporting it. Insert this assembly into another drawer ( Fig. 4D and 5D, part B1) and slide it into the stand as shown in Fig. 4D and Fig. 5D. In case that sterile conditions are needed, considering the nature of the microorganisms to be cultured, assemble this part in a laminar flow or a biological safety cabinet.
After the first assembly, it is recommended to install this part as the last step before the experimental phase starts. Be aware that the advised working volume should be 7.5-10 ml if the CultureLED will be installed on an orbital shaker.
Locking and final positioning (part C3): Step 1: Connect a Qwiic MultiPort to a 200 mm Qwiic cable which is connected to a RedBoard. Now, connect the Qwiic cables from the temperature sensor and motor driver to the MultiPort. The LED wires (data, 5 V, and ground) should be connected to their proper pins (section 5.5). Slide all four drawers with their components in the following order from bottom to top, as shown in Fig. 1B and Fig. 2B Step 2: After sliding the drawers, lock each drawer to its place with the locking pins (Fig. 2B, part C3) by inserting them into their dedicated holes in the side panels (Fig. 2B, parts A1 and A2).
Remote assembly (parts D1 to D2): The system remote designs are shown in Fig. 6A, B and C.
Step 2: Place the step 1 assembly to the remote (Fig. 6C, part D1) on top of the pins as shown in Fig. 6C and apply minimal pressure.
Step 3: Put the lid (Fig. 6C, part D2) on while the rounded hole is above the Twist -RGB Rotary Encoder Breakout as shown in Fig. 6C.
Step 4: Once the lid is closed, attach the SparkFun Clear Plastic Knob (Fig. 6C, part 3) to the Qwiic Twist -RGB Rotary Encoder Breakout (Fig. 6C, part 2) to lock the lid. The remote assembly is shown in Fig. 6.

Electronic Scheme:
The wiring diagram (Fig. 3) presents the electronic layout of the components. The parts should be connected and soldered accordingly.

Arduino INO sketch:
The code should be uploaded to the SparkFun RedBoard using the USB connector (more information can be found in https://learn.sparkfun.com/tutorials/redboard-qwiic-hookup-guide/all).

Operation instructions
Once the system's assembly described in section 5 is complete, use a 2-Way 2.1 mm DC Barrel Jack Splitter Squid to provide DC power to both the RedBoard and the Qwiic Motor Driver. Connect to the RedBoard (Fig. 7, part 1) DC jack (female) (Fig. 7, part 2) one end of the splitter (male) (Fig. 7, part 3). Connect the second end (male) (Fig. 7, part 4) to a Female DC Power adapter À 2.1 mm jack (Fig. 7, part 5). The Female DC Power adapter's screw terminal block should be connected to the Qwiic Motor Driver (Fig. 7, part 6) screw terminal block. The 2 DC fans and the Qwiic multiport should be connect to the Qwiic Motor Driver (Fig. 7, part 6) as indicated by the arrows. Connect the main splitter squid (female) (Fig. 7, part 7) to a 9 V DC power supply (male) (Fig. 7, part 8).

Remote operation
The remote allows an easy selection of stored light regime programs and intensities as well as monitoring the current temperatures. The remote is simply designed with one button (Qwiic Twist -RGB Rotary Encoder) that can be pressed in order to switch light program or twisted clockwise and counterclockwise in order to adjust the light intensity. The remote scheme is shown in Fig. 6A and described below.
Remote scheme description: Remote button -The button can be pressed to change a stored program or rotated clockwise/counterclockwise to change the light intensity. (Fig. 6A.1).
Light program number -The stored and selected programs can be changed by pressing the remote button (A), as explained in the INO file ( Fig. 6A.2).
Light program name -Each program has a number and a brief description (Fig. 6A.3, as programmed directly in the INO file). For example, in our code (CultureLED_CodeFeb2022.ino): Program #1: ''C:W"-C indicates continuous mode while W stands for white led color. This is the default mode. Program #2: ''C:W/WRB"-C indicates continuous mode while W/WRB, stands for LED's coloration. In this case, W indicates white, WRB indicates a mix of white, red and blue, R indicates red and B indicates blue. Our setup was 6 LEDs:3 LED W and 3 WRB.
Program #3: ''F:W/WRB"-F indicates flashing mode. The flashing time is indicated by the delay function set to 1000 ms. The LED color setup is like Program #2.
Temperature -The temperature reading output is shown in Celsius (default), but it can be changed to Fahrenheit as explained in the INO file (Fig. 6A.4).
Routine system operation: Once the system is assembled, every part can be unlocked by simply removing its locking pin ( Fig. 2A, part C3) and sliding it out from the stand. Nevertheless, in routine, the 6 well panel will be replaced more frequently. Other parts are likely to be taken out only during maintenance, between experiments, or in disassembly.

Validation and characterization
Microalgae cultivation: The validation of the system was done by two CultureLED systems that each contain one 6 well plate. The cultivation of Phaeodactylum tricornutum has been performed with an initial culture volume of 7.5 ml per well of artificial seawater -F/2 medium [24]. The CultureLED was installed on an orbital shaker (Digital Orbital Shaker, Heathrow Scientific, USA) set to a rotation speed of 75 RPM, installed inside a cooling incubator set to 25°C and under ambient CO 2 conc. (414 ppm). A set of three wells were treated with different light regimes, e.g., continuous white (CW); continuous white, red and blue (CWRB); flashing white (FW), and flashing white, red and blue (FWRB) (Fig. 8). The light intensities were 54 lmol photons m À2 s À1 in CW and FW regimes, and 33 lmol photons m À2 s À1 in CWRB and FWRB regimes. The light/dark period in flashing light regimes (FW, FWRB) was 1 s on/1 s off (0.5 Hz). Daily growth and growth rates were achieved by counting cells from each well, using a hemocytometer that contains quadrilateral gridded chambers with known volume, which enables cell quantification in a specific volume. The duration of the cultivation experiment was 9 days.

Cell growth rate results
As shown in Fig. 8, significant cell growth has been achieved for the cultures cultivated under continuous LED light, compared to flashing LED light. White light-based regimes (CW and FW) produced better growth than white, red, and blue lightbased regimes (CWRB and FWRB). P. tricornutum growth was better in continuous regimes compared to flashing regimes. The average maximum cell concentration in the CW regime was achieved at day 6 (11.1 Â 10 6 cells/ml) while the maximum average cell concentrations in CWRB, FW, and FWRB regimes were achieved two days later (day 8) and were 11.0 Â 10 6 , 8.1 Â 10 6 and 5.3 Â 10 6 cells/ml, respectively. Throughout the experiment period, it was observed that P. tricornutum grew better under continuous light regimes (e.g., up to $ 2.3 times more cells/ml on the last day of the experiment) (Fig. 8). Similar results have been achieved with Chlorella vulgaris, which was grown under 1 s/ 1 s (0.5 Hz) light/ dark LED light regimes, compared to continuous LED light regimes [18]. Nevertheless, various algal strains show different growth rates in other light regimes as shown in several publications [15,16,17,19]. We hope that the system users will examine other light regimes and different algal strains.

Conclusions
The protocol presents a 3D printer-based LED illumination cultivation system for multi-well culture plates that can be mounted on an orbital shaker or shelf. The bill of materials, assembly instruction and code allow third-party customization for different purposes or experimental requirements. The system parts can be printed and assembled within days using lowcost commercially available off-the-shelf materials, allows updating of electronic parts during their life cycle and implanting improvements and modifications. The modular drawer design is flexible allowing exchange of the panels, by this it is pos- sible to use different development boards, other multi-well plates (e.g., smaller volume wells), various LEDs and fans. The system can be located inside a growth chamber or growth room to allow temperature, humidity, and/or CO 2 control based on the experimental parameters.

Human and animal rights
Not applicable.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.