A study on the apterous genus Clytomelegena Pic, 1928 (Coleoptera, Disteniidae)

Abstract The genus Noeconia Murzin, 1988 is synonymized with Clytomelegena Pic, 1928. Clytomelegena kabakovi (Murzin, 1988), comb. n. is newly recorded from China (Guangxi Prov.). And Laos (Attapeu Prov.) is a new locality of this genus. Both sexes are apterous. Photographs and genitalic descriptions of Clytomelegena kabakovi are presented for the first time.


Introduction
The first author, Meiying Lin found an old strange Distenidae specimen in the collection of the Chinese Agriculture University in Beijing in the past. Surprisingly in 2011, additional specimens collected at the same locality in China were brought to her by Messrs. Xinlei Huang and Huihua Zeng. It was first determined as Noeconia kabakovi Murzin, 1988 with the help of her European friends. Later, the second author, Sergey V. Murzin visited her Institute and informed her that Noeconia kabakovi could be a synonym of Clytomelegena postaurata Pic, 1928. The genus Clytomelegena was first described by Pic (1928) on the basis of a unique specimen, C. postaurata Pic, 1928 from South Vietnam. Later in 1988, Murzin described the genus Noeconia on the basis of N. kabakovi Murzin, 1988 from North Vietnam. According to our study of the type specimens of these two genera, it is concluded that the genus Noeconia should be a synonym of Clytomelegena by the resemblance of the structures of antennae, prothorax, elytra, abdomen and lack of hind wings. However, these two species are thought to be different species in spite of the problem that the type specimen of C. postaurata seems to be a teneral individual.
As luck would have it, one specimen collected in Laos was brought to us as an addition to the abnormal unique type of C. postaurata, which suggests that C. postaurata and N. kabakovi are surely different species, and the elytral shape could be a useful character to separate species. As a result, it is indicated that C. postaurata is distributed in South Vietnam and Laos, and N. kabakovi is distributed in North Vietnam and South China. The Chinese fauna of the Disteniidae is thus updated to 3 tribes, 8 genera and 28 species (Lin et al. 2010).
Types and other material studied are deposited in the following institutions or private collections: tubercles behind middle; with a slight apical constriction, apical part subequal to or a little narrower than base. Scutellum pentagonal. Elytra depressed behind scutellum, swollen behind middle, evenly rounded apically. Hind wings reduced ( Fig. 11; not mentioned in either of the original descriptions). Antennae thin, about 1.5 to 1.8 times as long as body, 3 rd to 10 th antennal joints internally with recumbent undulating long hairs, reaching the apex of corresponding joint. Procoxal cavity open behind (Fig. 14). Femora spindle-shaped, petiolate (Fig. 7); male hind femora reach elytral apex. Middle tibiae with an oblique groove bearing a brush of hairs. 1 st joint of posterior tarsi shorter than or subequal to following two joints together.
Two flightless Oriental genera are known up to now: Clytomelegena Pic, 1928 andOlemehlia Holzschuh, 2011. Clytomelegena postaurata Pic, 1928: 11. Clytomelegena postaurata;Villiers 1958: 267;Jiang and Wu 1986: 5. Remarks. The unique type specimen deposited in MNHN is a newly emergent individual, which is difficult to compare with other specimens. The testaceous antennae and legs could be its color, or they would become as dark as the specimen from Laos or same to Murzin's kabakovi. The elytra are not fully sclerotized, making specific character coding such as maculae unclear but revealing the absence of hind wings without opening the elytra. The last segment of maxillary palp (Fig. 2) and the last visible sternite (Fig. 1b)   Redescription of species. Body length 8.8-14.5 mm, width at humeri 1.7-2.2 mm. Black; trochanters and bases of femora yellow; mouth parts, most parts of legs and antennae brownish. Body with long scattered erect setae and recumbent silvery pubescence, which is sparser on head and abdominal sternites and absent on ventral sides of head and prothorax. Elytra with a transverse band behind middle created by recumbent dark-brown setae and pubescence, of which width is about 1/4 of elytral length.
Head finely irregularly rugose between eyes, with longitudinal rugose sculpture under eyes and behind antennal bases. The last segment of maxillary palp stout (male, Fig. 8) or slender (female, Fig. 9). Pronotum longer than broad, with very fine and dense punctation. Elytra with 4 longitudinal rows of punctures, which are deep and hollow-shaped anteriorly and missing at middle, with very fine indistinct sculpturing between punctures, independently rounded apically, with a row of 7-10 pointed tubercles behind humeri. Antennae long and thin, 1.5 (female) to 1.8 (male) times longer than body; Scape dilated toward apex, reaching midlength of pronotum. Pedicel very small, spherical, hidden inside apical hollow of scape. The relative length of antennal joints (male and female almost same): 20:  Male terminalia (Figs 15-19): Tegmen approximately 1.6 mm in length; lateral lobes slender, approximately 0.5 mm long and 0.1 mm wide, apex with short setae; median lobe plus median struts slightly curved, subequal to tegmen in length; the median struts less than 1/3 of the whole median lobe in length; dorsal plate shorter than ventral plate; apex of ventral plate sharply pointed; internal sac moderately long, about twice the median lobe in length, bearing a basal armature (Fig. 17) and two apical rods of endophallus (Fig. 18), ejaculatory duct single (Fig. 18). Apex of tergite VIII truncated with rounded sides (Fig. 19). Female terminalia (Figs 20-23): Paraproct moderate in size, its baculi thick and long, straight and not bifurcate at base; valvifer baculum very thick at base and narrowed towards apex (Fig. 20b); coxite lobes sclerotized at each inner part, with tactile hairs; stylus articulated to the tip of each coxite lobe, sclerotized except for apex and bearing tactile hairs (Fig. 22); dorsal baculi straight and longer than paraproct baculi (Fig. 20a); proctiger baculi long and almost straight (Fig. 20a). Spermathecal capsule (Fig. 23) is complex and coiled, composed of two parts, with two openings to bursa copulatrix (or spermathecal duct); bigger one with basal 1/4 twisted, strongly curved near middle; the other small part also strongly sclerotized, curved and twisted at middle, connected with bigger part with a thin duct; spermathecal gland ( Fig. 23a) attached to middle of smaller part of capsule, membranous. Tignum (Fig. 21) slightly longer than half of abdomen. In one measured specimen, tignum was 2.3 mm for an adult with 4.2 mm abdomen length in ventral view.  Biology and ecology: Prior to this study, no biological or ecological information was published on this species. The second author S. Murzin collected some specimens of this species in Cuc Phuong National Park (N. Vietnam) on 3-5 May 1991 on leaves of different plants. On 5 June 2011, Huihua Zeng collected one specimen on the ground near a light trap, but it was not certain whether this was an accidental occurrence or whether the specimen was attracted by light. Later (9 July 2011), the same collector observed another specimen on a stump near the light trap, later crawling in the leaf litter on the ground (Figs 24-26). The light trap was located in Damingshan of Guangxi, a tropical rainforest, at the altitude of 1,200 m. The other collector, Xinlei Huang, also collected one specimen at the same locality, by sweep net, which likewise did not elucidate any information on its biology.
Eduard Vives collected one female on 14 June 2011 in Tam Dao National Park of North Vietnam. It was crawling in a very antlike manner on the trunk of a large, recently fallen tree (Fig. 27) that was also attracting many Agrilus (Buprestidae) and small Lamiinae (genus Sybra, Pterolophia, Exocentrus). The day was very sunny and Eduard watched this trunk for 80 minutes more and did not see any additional specimens of Clytomelegena (personal communication, Aug. 2011).
In 2012, 3 additional specimens were collected in North Vietnam from Cao Bang Province and Ninh Binh Province in April and May by an expedition of Steven Lingafelter, Eduard Jendek, and Pham Hong Thai. proving this manuscript. We thank Akiko Saito (Natural History Museum & Institute, Chiba, Japan) for comments on female genitalia, Eduard Vives (Terrassa, Spain) for comments on biology. Our special thanks are due to Olivier Montreuil and Thierry Deuve (MNHN), Xinli Wang and Siliang Liu (CAU), Huihua Zeng and Dong Wen (CWD), Petr Viktora from Kutná Hora, Czech Republic, Tomá Tichý from Opava, Czech Republic, Steven W. Lingafelter (USNM) and Xinlei Huang (IZAS) for giving us the permission to use the related collections and supporting of materials and information. This research was supported by a grant (No. O529YX5105) from the Key Laboratory of the Zoological Systematics and Evolution of the Chinese Academy of Sciences, and by NSFC program J0930004 and 31000967.