Dipsas nicholsi (DUNN, 1933)
Can you confirm these amateur observations of Dipsas nicholsi?
|Higher Taxa||Colubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Synonym||Sibynomorphus nicholsi DUNN 1933: 193|
Sibon nicholsi — DUNN 1940
Dipsas nicholsi — SMITH 1958
Dipsas variegata nicholsi — PETERS 1960: 137
Dipsas variegata — PETERS & OREJAS-MIRANDA 1970: 90
Dipsas nicholsi — CADLE & MYERS 2003
Dipsas nicholsi — WALLACH et al. 2014: 233
|Distribution||C Panama (endemic)|
Type locality: Chagres River and Pequeni River, Panama [i.e. the junction of the Río Pequení with the Río Boquerón in the ‘‘mid-basin’’ [= upper drainage] of the Río Chagres at approximately 9° 21’N, 79° 33’ W]. Map legend:
- Type locality.
- Region according to the TDWG standard, not a precise distribution map.
NOTE: TDWG regions are generated automatically from the text in the distribution field and not in every cases it works well. We are working on it.
|Types||Holotype: MCZ 37884 (head and neck only)|
|Comment||Snail-eater. Previously considered as subspecies or synonym of Dipsas variegata. Specimens from western Ecuador previously assigned to ‘‘Dipsas variegata nicholsi’’ represent a different species—Dipsas andiana (Boulenger),|
which has been resurrected from the synonymy of Dipsas oreas (Cope) by CADLE & MYERS (2003).
Diagnosis: Dipsas nicholsi is a pale brown snake with distinctive contrasting patterns on the head and dorsum. The head is relatively unmarked except for a bold blackish brown n-shaped marking extending from the anterior edge of the frontal or frontal/prefrontal sutures to the neck, where the branches are confluent with a pair of elongate dorsolateral blotches. Apart from the dorsal head marking and occasional narrowly darkened sutures, the head is unmarked. The blotches on the dorsum are black or blackish brown, strongly elliptical or oval and much broader than tall, and have a variably distinct narrow pale border. The interspaces are slightly broader than the blotches for the length of the body. Additional blackish streaks or irregular spots are sometimes present between the blotches. These pattern characteristics, particularly the form of the dorsal head marking and the dorsal blotches (including pale border), are constant in all specimens of D. nicholsi we have examined. Dipsas nicholsi has a relatively high number of ventrals (males 198–208, one female 200) and subcaudals (males 92–98, one female 95). However, scale characters overlap greatly among species of Dipsas and should not be used exclusively for identifications. The color pattern seems to be the most constant and readily diagnostic feature, as noted by Dunn (1933). No other known species of Dipsas from Panama or western Colombia and Ecuador, with the exception of D. andiana, has the distinctive head marking present in D. nicholsi. Dipsas nicholsi is very similar in color pattern and scutellation to D. andiana from western Ecuador [from CADLE & MYERS 2003].
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