Sonora occipitalis ( Hallowell 1854 )

Cox, Christian L., Davis Rabosky, Alison R., Holmes, Iris A., Reyes-Velasco, Jacobo, Roelke, Corey E., Smith, Eric N., Flores-Villela, Oscar, McGuire, Jimmy A. & Campbell, Jonathan A., 2018, Synopsis and taxonomic revision of three genera in the snake tribe Sonorini, Journal of Natural History 52 (13 - 16), pp. 945-988 : 975-976

Sonora occipitalis ( Hallowell 1854)

Rhinostoma occipitale Hallowell 1854:95 . Holotype: According to Mahrdt et al. (2001a), the holotype has been lost or is misplaced. Drawings based upon the holotype are on plate IV of Hallowell (1854). Type locality: ‘Mohave Desert’ of California, which Mahrdt

et al. (2001a) suggest is ‘in the region of the Mojave River, western San Bernardino County, California’.

Lamprosoma occipitale Hallowell 1856:311

Chionactis occipitale Cope 1860a:241

Chionactis occipitalis Cooper 1870:66

Holasoma occipitale Muller 1882:125

Contia occipitalis Garman 1884:91

Contia occipitale Brown 1901:68

Sonora occipitalis van Denburgh and Slevin 1913a:412

Sonora occipitalis Stickel 1938:183

Chionactis occipitalis occipitalis Stickel 1943:128

Chionactis occipitalis occipitalis Mahrdt et al. 2001a :731.1

Chionactis occipitalis Wood et al. 2014:10

Diagnosis

Sonora occipitalis can be distinguished from all other Sonora, except S. annulata and S. palarostris , by the presence of a flattened, spadelike rostrum. Sonora occipitalis can generally be distinguished from both S. annulata and S. palarostris by the lack of red crossbands (usually present in both S. palarostris and S. annulata ) and the brown coloration of crossbands. Additional morphological differences among S. occipitalis , S. palarostris and S. annulata are summarized in Wood et al. (2014).

Variation

Most S. occipitalis lack red crossbands, but some populations have individuals with red crossbands (less than 10%). There is variation in the number of black crossbands, but there are usually more than 45.

Distribution

Wood et al. (2014) restrict this species to the Mojave desert in south-eastern California, south-western Nevada, and north-western Arizona ( Figure 5 ).

Remarks

This species is in the subgenus Chionactis along with S. annulata and S. palarostris .

Figures

Figure 5. Map of the geographic distribution from IUCN and georeferenced occurrence records from GBIF (grey crosses) for the subgenus Chionactis, including Sonora occipitalis, S. palarostris and S. annulata. The top of the map has images of the bicoloured (a), and tricoloured (b) morphs of S. occipitalis. The side panel (c) depicts S. plarostris. The bottom panel depicts the bicolour (d) and tricolour (e) morphs of S. annulata. Photos by T. Brennan (a, b, and c) and M. Mulks (d and e). Colours of shaded ranges and circular points on the map correspond to the phylogenetic tree in Figures 1 and 2.