Two new species of Melanorivulus from the Caiapos hill, upper Araguaia river basin, Brazil (Cyprinodontiformes: Rivulidae)

作者：Costa Wilson J E M^*

来源：Ichthyological Exploration of Freshwaters, 2012, 23(3): 211-218.

Melanorivulus ubirajarai, new species, and Melanorivulus kunzei, new species, are described from the upper Araguaia river basin, central Brazil; both are considered as closely related to other species endemic from the same area. Melanorivulus ubirajarai shares with M. litteratus a unique colour pattern of caudal fin in females (short grey stripe between caudal spot and bar on the middle of the fin). Melanorivulus kunzei shares with M. kayapo a unique colour pattern of flank in males (irregular horizontal rows of red dots forming reticulate pattern). Melanorivulus ubirajarai is mainly distinguished from M. litteratus by having a distinct colour pattern of flank and dorsal fin in males, consisting of not overlapping chevron-like red oblique bars on the flank and rows of light grey spots on the dorsal fin in males, dorsal fin at vertical through the base of the 9th anal-fin ray, and 33-35 scales on the longitudinal series. Melanorivulus kunzei mainly differs from M. kayapo by having 29-30 caudal-fin rays and the presence of dark grey dots on the sub-distal portion of the dorsal fin and middle of caudal fin in males. The discovery of the two new species supports the recent report of a unique high species diversity of Melanorivulus in the area drained by rivers originating in the Caiapos hill. The combination of high species diversity with quick habitat loss makes rivulid species endemic to the Caiapos hill area highly threatened with extinction, deserving special concern.

• 出版日期2012-11