Oscura, Mcmahan, Caleb D., Matamoros, Wilfredo A., Piller, Kyle R. & Chakrabarty, Prosanta, 2015

Mcmahan, Caleb D., Matamoros, Wilfredo A., Piller, Kyle R. & Chakrabarty, Prosanta, 2015, Taxonomy and systematics of the herichthyins (Cichlidae: Tribe Heroini), with the description of eight new Middle American Genera, Zootaxa 3999 (2), pp. 211-234 : 225-226

Genus Oscura gen. nov., McMahan and Chakrabarty 2015

( Fig. 13 )

Inclusive species. O. heterospila (type by monotypy).

Diagnosis. Oscura is diagnosed by a large, round or oblong, dark blotch filling the entirety (or nearly the entirety) of the caudal peduncle and the presence of small black spots on scales covering the sides of the body. Species of this genus possess an overall dark body coloration. This genus is most similar to Vieja ; however, Oscura possesses dark bars down the body (typically five) and a blotch that fills the entirety of the caudal peduncle, versus the absence of broad bars down the body and a caudal blotch not filling the entirety of the caudal peduncle in members of Vieja .

Distribution. Atlantic slope of Mexico and Guatemala in the Río Usumacinta drainage. Etymology. Gender feminine. “ Oscura ” is the Spanish word for dark, in reference to the overall dark coloration that is characteristic of members of this genus.

Comments. The body shape and large, dark caudal blotch of this species initially allied this species in Vieja , but all phylogenetic studies to date have recovered them to be distantly related. The increased taxon sampling of the present study, as well as the analysis of Říčan et al. (2013) recovered this species in its own clade and the sister group to Rheoheros . Given the recovered phylogenetic position and the morphological distinctiveness of this species compared to its closest relatives ( R. lentiginosus and R. coeruleus ), we recognize this species in its own (monotypic) genus.

Material examined. LSUMZ 16229 [n=5, Guatemala: Río La Pasion], LSUMZ 16471 [n=1, Guatemala: Río La Pasion], UMMZ 144313 [n=5, Guatemala: Río San Pedro], FMNH 108978 [n=1, Guatemala: Río San Pedro], FMNH 108993 [n=18, Guatemala: Río Usumacinta], FMNH 108990 [n=3, Guatemala: Río Usumacinta].

Figures

FIGURE 13. Oscura heterospila, FMNH 108978, 98.79 mm SL.