Two new species of the genus Notropis Rafinesque, 1817 (Actinopterygii, Cyprinidae) from the Lerma River Basin in Central Mexico

Abstract

Prior findings suggest the existence of undescribed species among the cyprinids of central Mexico. Within the genus Notropis distributed across central Mexico and adjacent areas sometimes reaching southern basins, two groups have been recognized: a Southern Mexican clade and a central Mexican clade. Within this last clade, Notropis calientis has been defined as a species complex of four small minnows inhabiting upland areas. Here we describe two new species of this complex based on morphometric, meristic and genetic characters. Notropis marhabatiensis sp. nov. was diagnosed according to the following set of characters: 7, rarely 8, branched pelvic fin rays (vs. 8, rarely 7 or 9, in other species of the N. calientis complex) and 9, rarely 8, scales in a transverse series (vs. 10, rarely 9 or 11 in N. grandis & N. calientis); a dark, narrow lateral stripe running from around the pectoral fin to the caudal peduncle origin; and twentysix fixed nucleotide positions in the cytochrome b gene. The diagnosis of Notropis grandis sp. nov. was based on: 6, rarely 7, branched fin rays (vs. 7, rarely 6 or 8, in N. marhabatiensis, N. calientis and N. aulidion and 8, rarely 7 or 9, in N. calbazas and N. amecae), 42, rarely 40-41, or 43-45 scales in a lateral series (vs. 40, rarely 37-39, in N. calabazas; 35- 36, rarely 37-39, or 33-34 in N. amecae; 35, rarely 31-34, or 36 in N. marhabatiensis and N. calientis and 34, rarely 30-33, or35 in N. aulidion) and 11 rarely 10 or 12 gill rakers in the first arch; a dark lateral stripe widening from approximately the pectoral fin origin to the dorsal fin origin, forming a slightly convex segment; adult animals larger (n=30, ? ? =42.6, SD=4.69) relative to N. calientis (n=55, ? ?= 33.3, SD= 3.28) and N. marhabatiensis sp. nov. (n=30, ? ?= 30.5, SD=7.57) (F = 16.87; p < 0.001); and finally 31 fixed nucleotide positions in the mitochondrial gene cytochrome b sequence along with four amino acid changes. Calculated genetic distances between the new species and other species of the complex ranged between ? D GTR = 6.1% to 7.4% for N. marhabatiensis and ? DGTR = 6.3% to 8.1% for N. grandis.