A Taxonomic Reevaluation of the Night Snake Hypsiglena Ochrorhyncha and Relatives
1965; Southwestern Association of Naturalists; Volume: 10; Issue: 2 Linguagem: Inglês
10.2307/3669161
ISSN1943-6262
Autores Tópico(s)Scarabaeidae Beetle Taxonomy and Biogeography
ResumoThe cream-colored band anterior to the dark nuchal blotch of Hyp- siglena torquataadequately distinguishes all individuals of this species from the taxon H. ochrorhyncha which during the last 20 years has been treated (the present author believes incorrectly) as a subspecies of H. torquata. Resurrection of H. ochrorhyncha as a species removes the unsatisfactory sympatry of 2 races of H. torquata in south- ern Tamaulipas and in a broad area of the Pacific coastal plain of Western Mexico. Inspection of numerous specimens of Hypsiglena leads me to propose that the characters of the cream-colored band anterior to the dark nuchal blotch, and the dark ground color, of H. torquata can be used as diagnostic characters of that species; H. ochrorhyncha, which Bo- gert and Oliver (1945) treated as a subspecies of H. torquata, never has such a band and has paler ground color. The treatment of Bogert and Oliver leaves an unsatisfactory situation in that H. torquata jani (including H. torquata texana; cf. Duellman, 1961, with whom I con- cur) and H. torquata ochrorhyncha overlap geographically (but do not intergrade morphically) with H. torquata dunklei in southern Tamaulipas, with H. torquata torquata in a 300-mile strip of the Pa- cific lowlands from Guirocoba, Sonora to Mazatlan, Sinaloa and with H. torquata affinis near Magdalena, Jalisco (Fig. 1). The solution to this problem by Bogert and Oliver was to suggest that all the differ- ences in pattern were controlled by a single gene and that therefore both patterns can be expected in the same litter, in the region of over- lap. No evidence of this has been adduced. And, considering the com- plexity of the traits involved, very likely none will be. A more elegant and plausible resolution is achieved simply by rejecting the taxonomy of Bogert and Oliver, and resurrecting H. ochrorhyncha as a species. In each instance where the two species have been taken together the nuchal pattern easily separates the two forms. At the time Bogert and Oliver (1945) examined their specimens, the distribution of H. torquata in Mexico had not been fully determined, nor were there sufficient specimens of H. torquata to evaluate variation in scale char- acters. I have examined all of the available specimens of H. torquata dunklei from the Mexican state of Tamaulipas (Dixon, 1962), and 86 specimens of H. ochrorhyncha jani and H. o. ochrorhyncha from the
Referência(s)