Largenose Earth Snake

description

Description: A species with fused prefrontals and internasals; a loreal; a pointed rostral; nasal pierced by nostril on each side of head; a preocular and two postoculars; hexagonal frontal, contacting internasals; temporal formula 1 + 2; 7 or 6 upper labials and 6 lower labials; 2 or 2.5 upper labials before eye; genial shields separated by one or two scales; a mean of 123.3 ventrals (116 – 138), and 31.6 subcaudals (20 – 43); 17 rows of smooth scales at midbody; dorsum light cinnamon or beige, with vertebral line of hexagonal spots; venter yellowish, with intercalated black dots. Measurements: Adult specimens of Conopsis nasus average 202.1 mm snout­vent length (100 – 320 mm), 238.1 mm in total length (120 – 385 mm), body diameter 7.6 mm. Variation: Of all specimens examined only two had prefrontals and internasals divided. Loreals present on both sides of head (75.6 %), absent (15.6 %), or absent on one side of head (8.7 %). Upper labials usually 7 (84.5 %), 6 (8.6 %), or less than 6 (6.9 %). The latter percentage corresponds to a population in Chihuahua. Lower labials 7 (34.5 %), 6 (48.3 %), or less than 6 (17.2 %). Upper labials before eye 3 (13.7 %), 2.5 (75.8 %) or 2 (10.3 %

Taxonomic summary of Conopsis, Günther, 1858 (Serpentes: Colubridae)

diagnosis

Diagnosis: This snake is characterized by the following combination of characters: fused prefrontals and internasals; upper labials 7, 6 lower labials (some populations with reduced number of these scales); light cinnamon dorsal coloration; with a vertebral line of hexagonal spots that may be bordered by two paravertebral rows of spots. Ventrally it is yellowish, with intercalated black dots. It differs from C. megalodon, the only species with which it could be mistaken, by the light cinnamon dorsal coloration, its larger body size (SVL: 100 – 320 mm in C. nasus and 107 – 250 mm in C. megalodon), and by its distributional range in the Mesa Central, which does not overlap with C. megalodon.

Taxonomic summary of Conopsis, Günther, 1858 (Serpentes: Colubridae)

distribution

Distribution: Conopsis nasus is distributed in north­central Mexico (fig. 7); it has been collected in the states of Chihuahua, Aguascalientes, Distrito Federal, Durango, Guanajuato, Hidalgo, Jalisco, Estado de Mexico, Michoacan, Morelos, Puebla, Queretaro, San Luis Potosi, Sinaloa, Tlaxcala, Veracruz and Zacatecas, from 1515 to 2950 m, in xerophilous underbrush, oak, pine, and fir forest. It is usually under rocks or logs during every month of the year, being more abundant from June to September.

Taxonomic summary of Conopsis, Günther, 1858 (Serpentes: Colubridae)

materials_examined

Type specimen: BMNH lost; neotype BMNH 83.4.16.38. Type locality: Milpas, Durango.

Taxonomic summary of Conopsis, Günther, 1858 (Serpentes: Colubridae)