Mexican species of the genus Heterandria, subgenus Pseudoxiphophorus (Pisces: Poeciliidae)

The subgenus Fscucld.xiphophorus is currently regarded as monotypic.with a single widespread species, Hctcnuulria hiimiciihitu.inhabiting the Atlantic slope of Middle America.Actually, the taxon includes two sharply distinct species in Mexico, the more primitive being H. jonesi; other species of Fsciuloxiphoplionis occur in Guatemala.The basis for recognizing subgenera of Hcterandria is presented as well as a detailed comparison between H. himaculata and H. jonesi.including illustrations of gonopodia.gonopodial suspensoria, and the whole fish.Hetcruudrui jonesi, which occurs at elevations up to 2,385 meters, is close to the ancestral stock of the genus.RESUMEN.-El subgenero Pseudoxiphophoms.de acuerdo a la literatura corriente.es considerado como monotipico.con una sola especie de amplia distribucion, Hetenindriu himaculata.que habita la vertiente Atlantica de Mexico y America Central.Como se muestra aqui, en Mexico hay dos especies claramente distintas, la mas primitiva siendo //.jonesi: otras especies de Pseudoxiphophoms existen en Guatemala.La base para reconocer subgeneros de Heterandria se presenta asi como una comparacion detallada entre H. hinuiculata y H. jonesi.incluyendo ilustraciones de gonopodios, suspensores de gonopodio, y ademas de el pez completo.Heterandria jonesi.que occure a alturas hasta 2.385 metros, es cercano a el tronco ancestral de el genero.Until the recent general review of the Poeciliidae by Rosen and Bailey (1963), Heterandria and Pseudoxiphophonts were regarded as monotypic genera represented, respectively, by H. formosa Agassiz in Florida and adjacent coastal lowlands, and by P. bimaculatus (Heckel) from northeastern Mexico southward and eastward into Nicaragua.Among ichthyologists publishing on Pseudoxiphophoms during this century, only Regan (1904)(1905)(1906)(1907)(1908)(1909)(1910)(1911)(1912)(1913) consistently maintained that this subgenus comprises two fully distinct species, although Hubbs (1924Hubbs ( -1936) ) divided P. bimaculatus into four subspecies, including the one that is here restored to full specific status.Rosen and Bailey (1963: 131), commenting on Hubbs' action, indicated that the characters distinguishing these forms "are apparently clinal and grade imperceptibly from one race to another."In attempting to distinguish forms oi Pseudoxiphophoms, overemphasis has been placed on the dorsalray number which varies widely in the two species of this group in Mexico.As usual in poeciliids, the detailed architecture of the gonopodium proves to have far more important systematic value, although the size and position of the dorsal fin is also highly useful.Color pattern helps to distinguish the Mexican species (Pseudoxiphophoms) but it is too variable for complete reliance.Regan was correct in concluding that P. Jonesi (restricted to east-central Mexico) and P. bimaculatus are distinct species, even though the male of jonesi was unknown to him.As here shown for the first time, the gonopodium of Heterandria Jonesi is consistently and sharply distinct from that of H. bimacukita.Although these species have overlapping ranges they are rarely taken together, as in central Veracruz (see below).My paper on the zoogeography of Middle American freshwater fishes (Miller, 1966) did not include the extralimital H. Jonesi, but recognition of more than one species of Pseudoxiphophoms in Mexico was implied in the range statement for Heterandria bimacukita, since the subgenus Pseudoxiphophoms ranges northward into southeastern Tamaulipas.This paper presents a detailed comparison between H. Jonesi and H. bimacukita in Mexico, illustrates their distinctive gonopodia and suspensoria as well as the general form and appearance of each species, and discusses variation in coloration, body proportions, and meristic characters.The distribution of the two species is also treated and support is presented for the view that H. Jonesi is closest to the common ancestor of the genus.