Hypsiglena jani

Taxonomy of Hypsiglena has received some critical review since Tanner's revision of the genus in 1944. Dixon (1965) and Dixon and Dean (1986) studied a morphological contact zone between northern and southern taxa at the Sonora–Sinaloa border in Mexico, finding that it comprised a narrow zone of hybridization with some taxa existing in sympatry. Hardy and McDiarmid (1969) examined specimens across the range of this presumptive contact and elsewhere in western Mexico and concluded that no morphological characters existed to separate torquata and ochrorhyncha, except maybe nuchal patterns, which they decided (p. 170) was "a case of pattern dimorphism in a single, otherwise uniform, species." Grismer et al. (1994) dismissed the recognition of subspecies in Baja California, stating, without evidence, that the subspecies intergrade widely. Mulcahy (2008) conducted a comprehensive phylogeographic study of Hypsiglena based on an mtDNA analysis of >150 individuals. Mulcahy (2008) recognized six species in what was considered H. torquata, five of which are consistent with previously described lineages (e.g. subspecies), while one represents a unique lineage that remains to be described. Mulcahy (2008) also recommended maintaining the subspecies designations for several of the widespread, polymorphic species, which may represent incipient species. The nominal species H. torquata is now restricted to Mexico, three described forms occur in the USA, and the undescribed form is endemic to the Cochise Filter Barrier area of southeastern Arizona and associated New Mexico (Crother 2017).

Range extends from southwestern and southeastern Colorado and southwestern and south-central Kansas south through most of eastern Arizona, New Mexico, western Oklahoma, and most of Texas (but not most of eastern Texas) to central and northeastern Mexico (Mulcahy 2008). Mulcahy's (2008) figure 2 appears to indicate that Hysiglena chlorophaea and H. jani both occur in the Fours Corners region (UT, CO, AZ, NM). Occurrence of H. j. texana in Montezuma County, Colorado, is of interest because specimens from nearby Mesa Verde in the same county generally have been assigned to subspecies loreala, which Mulcahy (2008) included in H. chlorophaea. The two areas differ in general habitat conditions (lowland shrubland at the texana site versus upland woodland at Mesa Verde).

This species is represented by a large number of occurrences or subpopulations.

No major threats have been identified. In many areas the rocky habitat tends to be unsuitable for incompatible human uses.