Cyprinid Fishes of the Subgenus Cyprinella of Notropis. IV The Notropis galacturus-camurus Complex

Abstract

The species Notropis galacturus and N. camurus are redescribed and differentiated -from other species of the subgenus Cyprinella and synonymies are given. These two species form a distinct unit within the subgenus, distinguished by the presence of depigmented basicaudal areas, a hiatus between nuptial tubercles of the snout and those of the top of the head, two rows of tubercles on each chin ramus, and red pigment in dorsal and anal fins of breeding males. Populations of N. galacturus east and west of the Mississippi have differentiated slightly. Lower Mississippi populations of N. camurus are racially dis- tinct from those in the Arkansas system. The two species are probably derived from a common stock which became divided into eastern and western portions. N. galacturus has crossed the Mississippi, but the range of N. camurus appears to have contracted, leaving the two present populations. The systematic situation in the subgenus Cyprinella has been out- lined in the first paper of this series, and the two variable species N. spilopterus and N. venustus treated in subsequent parts (Gibbs, 1957a, b, c). Notropis galacturus and Notropis camurus stand apart from most of the species of Cyprinella as a unit, defined by a num- ber of characters which they have in common. First, and most notable, both have depigmented areas at the caudal base which, at their fullest development, are quite prominent. Occasionally in other species of Cyprinella a specimen is found which has such depigmentation, but the character is never common. An unrelated species which is sympatric with N. galacturus in the Tennessee system, Notropis coc- cogenis, also has prominent depigmented caudal areas, but this is surely a case of parallelism. The breeding males of both N. galacturus and N. camurus have greatly enlarged dorsal fins and red pigment in both dorsal and anal. Their tubercle patterns are similar, notably in the lack of a hiatus between the tubercles of the top of the head and those of the snout, in the minuteness of the nape tubercles, and in the presence of two rows on each chin ramus. This paper redescribes the species N. galacturus and N. camurus, treats their intraspecific variation, and discusses their possible origin and means of dispersal.