Sonora michoacanensis (DUGÈS, 1884)
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|Higher Taxa||Colubridae, Colubrinae, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||E: Michoacán Ground Snake|
S: Culebra de Tierra de Michocán
|Synonym||Contia michoacanensis DUGÈS in COPE 1884: 178|
Elapomorphus michoacanensis – COPE 1895
Homalocranium michoacanense – GÜNTHER 1895
Chionactis michoacanensis – COPE 1896
Scolecophis michoacanensis – BOULENGER 1896
Sonora michoacanensis — DUNN 1928
Sonora michoacanensis — ECHTERNACHT 1973
Sonora erythrura TAYLOR 1937
Sonora michoacanensis — LINER 1994
Sonora michoacanensis — PONCE-CAMPOS et al. 2004
Sonora michoacanensis — LINER 2007
Sonora michoacanensis — COX et al. 2012
Sonora michoacanensis — WALLACH et al. 2014: 680
Sonora (Eosonora) michoacanensis — COX et al. 2018: 977
|Distribution||Mexico (Colima, Guerrero, Michoacan; Morelos, Puebla)|
Type locality: Michoacan, Mexico (neotype locality). Restricted to ‘Apatzingan, Michoacán’ by Smith & Taylor (1950).
erythrura: Mexico (Guerrero); Type locality: Mexico: 10 mi S Taxco, Guerrero;
|Types||Neotype: BMNH 19188.8.131.52|
Holotype: INHS (= UIMNH) 25063 (5440), E. H. Taylor; July 17, 1936. [Sonora erythrura]
|Diagnosis||Diagnosis: This species can be distinguished from S. mutabilis based on the almost invariable absence of banding on the tail, and from S. aemula based on the absence of a file-like tail (Fig. 13). We note that one specimen from the University of Michigan Museum of Zoology (UMMZ 109904) has a single narrow band on the tail [COX et al. 2012].|
Variation: This species is extremely variable in colour pattern, ranging from uniform red to banded tricoloured pat- tern (Echternacht, 1973). In tricoloured animals, the num- ber of bands and shape of bands varies greatly (Echternacht, 1973). In some individuals, the black and yellow bands ap- pear as black-bordered yellow spots (Fig. 7). Morphological measurements and meristic characters are mostly overlap- ping between S. mutabilis and S. michoacanensis (Table 3). The hemipenis is depicted in Cope (Cope, 1895, Plate XXIX, Fig. 6) [COX et al. 2012].
Original description from DUGÈS in COPE 1884: Muzzle moderately prominent, rounded; eye moderate; body cylindric; tail short, acute at end, not slender. Scales without fossae.Rostral plate much wider than high. Internasal small. Frontal large, longer than wide, posterior angle obtuse. Superciliaries moderate, much narrowed anteriorly. Parietals as long as the frontal, rounded posteriorly. The single nasal is narrow and is obliquely placed, being in contact by its posterior border with both the prefrontal and loreal, and not touching the second superior labial. Loreal longer than high. Preocular touching prefrontal and third superior labial. Two postocular, the inferior resting on the fourth and fifth superior labials. Temporals 1-2. Seven superior labials, the third and fourth entering the orbit, the sixth very small. Six inferior labials, of which four are in contact with the geneials; post-geneials one-third the length of the pregeneials. Between the former and the gastrosteges, seven rows of small scales. Scales in fifteen rows. Gastrosteges, 152 : anal divided; urosteges, 37.
Ground color probably red in life; in alcohol it is a clear yellow. A large black spot covers the frontal, and the superciliaries, less their anterior extremities, surrounds the eye, and terminates on tlie loreal, and tlie corresponding superior labials. It extends also on the antero-internal angles of the parietals. Another black spot forms a wide collar interrupted on the median line below. Then follow thirteen transverse rings, each occupying five or six rows of scales on the back, narrowing below, where some of them are interrupted. Two of the rings are so wide as to lead to the belief that each of them consists of two rings united, so that the whole number is sixteen. Tail unspotted. The third, fifth, seventh and ninth interspaces from the head have the scales black-tipped, and are wider than the black bands. The skin has an elegant clear blue reflection.
|Comment||Subspecies: Sonora michoacanensis mutabilis STICKEL 1943 has been elevated to full species status.|
|Etymology||Named after the type locality.|
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