Proechimys Chrysaeolus

''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.'':

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.
* Group ''semispinosus'': it contains two species, ''Proechimys semispinosus'', — with its widespread range, from Central America south from Honduras along the west coast of Colombia and Ecuador — and ''P. oconnelli'', with a more limited range, east of the Cordillera Oriental in the north-western Amazon.
* Group ''longicaudatus'': it contains the three species ''Proechimys longicaudatus'', ''P. brevicauda'', and ''P. cuvieri'', united by lyrate and strongly fanged incisive foramina, and deep groves extending onto the anterior palate. They range from the lowland rainforest of the Guianan region and Amazon basin to dry forests of eastern Bolivia, northern Paraguay, and central Brazil.
* Group ''guyannensis'': it contains the two species ''Proechimys guyannensis'', and ''P. roberti'', showing a plantar surface of hindfeet with six pads, and distributed mostly in the Guianan region, eastern Amazonia, and extending south into central Brazil.
* Group ''trinitatus'': it contains the eight species ''Proechimys trinitatus'', ''P. mincae'', ''P. guairae'', ''P. poliopus'', ''P. magdalenae'', ''P. chrysaeolus'', ''P. urichi'', and ''P. hoplomyoides''. These taxa possess large and open incisive foramina, and simplified cheek teeth.
* Group ''goeldii'': it contains the three species ''Proechimys steerei'', ''P. quadruplicatus'', and ''P. goeldii'', united by a uniformly large body size. Members of this group most commonly inhabit the seasonally inundated várzea or igapó lowland forests of the Amazon basin.
* Group ''gardneri'': it contains the three species ''Proechimys gardneri'', ''P. pattoni'', and ''P. kulinae'', characterized by short head and body length — less than . They are distributed in western Amazonia, but with non-overlapping ranges as all three species replace one another along the length of the Juruá River or on its opposite banks.

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

{{Authority control

Myocastorini
Rodent genera
Taxa named by Joel Asaph Allen