Genus of mammals belonging to the spiny rat family of rodents
Proechimys is a genus of South American spiny rats of the family Echimyidae. All species of the genus are terrestrial. In the lowland Neotropical forests, "Proechimys" rodents are often the most abundant non-volant mammals. They are recognizable by reason of their elongated heads and long rostra, large and erect ears, narrow and long hind feet, and tails always shorter than head-and-body lengths. The dorsal pelage comprises a mixture of expanded, varyingly stiffened spines (or aristiforms) — hence the vernacular name of spiny rats — and soft hairs (or setiforms).
"Proechimys" is the most speciose genus of the rodent family Echimyidae, with 25 species recognized, followed by "Phyllomys" with 13 species, and "Trinomys" with 11 species.
Phylogeny.
Genus level.
The genus "Proechimys" is the sister group to the genus "Hoplomys" (the armored rat). In turn, these two taxa share evolutionary affinities with other Myocastorini genera: "Callistomys" (the painted tree-rat) and "Myocastor" (the coypu or nutria) on the one hand, and "Thrichomys" on the other hand.
Species level.
Reconstructing the systematics and phylogeny of "Proechimys" species have been greatly hampered by extreme levels of within- and among-population character variability. This difficulty has been emphasized by Pine "et al.":
 ;templatestyles src="Template:Blockquote/styles.css" / ;Among the rodents, "Proechimys" remains what may be the most problematical genus taxonomically in all mammaldom.
To infer the phylogeny of "Proechimys" at the species level, morphological characters and mitochondrial DNA sequences have been used, and allowed to group species into major clades but whose interrelationships remain unresolved. Six species groups were identified (group "semispinosus", group "longicaudatus", group "guyannensis", group "trinitatus", group "goeldii", and group "gardneri"), and 4 species ("Proechimys simonsi", "P. echinothrix", "P. canicollis", and "P. decumanus") remained unaffiliated to any of these groups.
The different groups of species can be diagnosed as follows.
Distribution.
"Proechimys" species presently occur mainly in South America, in all countries except Argentina, Uruguay, and Chile. One member of the genus ("P. semispinosus") also ranges into Central America.
References.
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