Arrhyton supernum HEDGES & GARRIDO, 1992
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Arrhyton supernum
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| Higher Taxa | Colubridae (Dipsadinae), Alsophiini, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) |
| Subspecies | |
| Common Names | E: Oriente Black Racerlet, Oriente Black Groundsnake |
| Synonym | Arrhyton supernum HEDGES & GARRIDO 1992: 171 Arrhyton supernum — CROTHER 1999 Arrhyton supernum — ZAHER et al. 2009 Arrhyton supernum — WALLACH et al. 2014: 56 Arrhyton supernum — DÍAZ et al. 2021 |
| Distribution | Cuba Type locality: "SW slope of El Yunque de Baracoa, Guantánamo Prov., Cuba, 136 m" |
| Reproduction | oviparous |
| Types | Holotype: MNHNCU 2704 |
| Diagnosis | Diagnosis: A moderate-sized species of Arrhyton distinguished from all others by its very dark coloration, dorsally and ventrally, with two occipital spots. Additionally, it can be distinguished from nonCuban Arrhyton by its 17 (versus 19) dorsal scale rows at midbody. Among Cuban species (all with 17 rows) it can be separated from A. taeniatum (Fig. 2A) by its fewer ven trals (124-128 versus 168-189) and the presence of a loreal scale (these counts and others are taken largely from Schwartz and Garrido, 1981: their Table 1). From all other Cuban species, it can be distinguished by its very smallloreal, 1/3 - 1/2 size of the preocular (3/4-2 times preocular in other species). Arrhyton vittatum (Fig. 2B) has fewer ventra Is (107-123 versus 124-128) and subcaudals (58-81 versus 107-108); A. sp. novo (see below) and A. tanyplectum have more ventrals (> 138) and subcaudals (> 121). Although ventral (123-132) and subcaudal (101-127) counts of A. dolichura overlap with those of A. supernum, the larger loreal, in contact with supralabials one and two (two only in A. supernum), and a diffe rent dorsal pattern (Fig. 3B) will easily distinguish those two species. Arrhyton ainictum Schwartz and Garrido, 1981 is a larger species (363 mm versus 255 mm snout-vent length, SVL), has more ventrals (137), a larger loreal, and has a lighter and very different d orsal pattern consisting of a sharply defined cephalic cap (absent in adult A. supernum), five stripes (not three), and an immaculate venter (not heavily pigmented), and it lacks the distinctive occipital spots of A. supernum. The most pertinent corn parison is with A. landoi (Fig. 2C) , which also occurs in Guantanamo Province and which may be sympatric with A. supernum. The subcaudal counts of female A. landoi (69-96) are lower than that of the single female A. supernum (107), but those of the males overlap slightly (78-111 in landoi, 108 in supernum). Both specimens of A. supernum have eight infralabials (nine on one side in paratype) whereas 29 of 32 A. landoi have >8 (modally nine). Temporals two and three (anterior) of A. landoi are rectangular, elongate, and have an even outer margin whereas those of A. supernum are irregularly shaped, less elongate, and have an uneven outer margin. In coloration, A. landoi has a white venter, a distinct light temporal band, a reddish brown cephalic cap (usually), and the lateral line often occupies the middle of the fourth scale row; A. supernum has a heavily pigmented venter, an obscure temporal band, a dark brown head, and the lateral stripe is wider and occupies the upper half of the third and most of the fourth scale rows (from Hedges & Garrido 1992: 172). |
| Comment | A. supernum has a heavily pigmented venter (immaculate in A. redimitum and A. landoi), a dark brown head lacking a well-defined cap or temporal band (reddish brown cephalic cap and well-defined temporal band present in A. redimitum and A. landoi), dorsal scales blackish (spotted with brown in A. redimitum and A. landoi), and a wide lateral stripe that occupies the upper half of the third and most of the fourth scale row (narrow lateral line occupying the middle of the fourth scale row in A. redimitum and A. landoi). Distribution: see map in Díaz et al. 2021: Fig. 5. |
| Etymology | Named after Latin “supernum” meaning celestial, in allusion to the dark (as in the celestial sky) coloration of this species. |
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