Dipsas palmeri (Boulenger, 1912)

Arteaga, Alejandro, Salazar-Valenzuela, David, Mebert, Konrad, Penafiel, Nicolas, Aguiar, Gabriela, Sa ́ nchez-Nivicela, Juan C., Pyron, R. Alexander, Colston, Timothy J., Cisneros-Heredia, Diego F., Yanez-Munoz, Mario H., Venegas, Pablo J., Guayasamin, Juan M. & Torres-Carvajal, Omar, 2018, Systematics of South American snail-eating snakes (Serpentes, Dipsadini), with the description of five new species from Ecuador and Peru, ZooKeys 766, pp. 79-147 : 98-99

Dipsas palmeri (Boulenger, 1912) Fig. 1r, s

Leptognathus palmeri Boulenger, 1912: 422. Holotype BMNH, a male from El Topo, province of Tungurahua, Ecuador.

Leptognathus latifasciatus Boulenger, 1913: 72. Holotype BMNH 1946.1.2007, a juvenile male from Upper Marañón, department of Cajamarca, Peru.

Dipsas peruana Harvey & Embert, 2008: 79 (part).

Proposed standard English name.

Palmer’s Snail-Eater

Proposed standard Spanish name.

Caracolera de Palmer

Diagnosis.

Dipsas palmeri differs from all described species of Dipsas based on the following combination of characters: (1) 15/15/15 smooth dorsals with enlarged vertebral row; (2) one loreal and one preocular in contact with orbit; (3) 8-10 supralabials with (usually) 4th to 6th contacting orbit; (4) one pair of infralabials in contact behind symphysial; (5) 172-202 ventrals in males, 181-200 in females; (6) 91-118 divided subcaudals in males, 86-102 in females; (7) dorsal and ventral ground color light brown with various degrees of fine black speckling and with 32-41 brown to blackish, white-edged circular blotches that are longer than interspaces in the first half of the body, but shorter in the second half (Figs 1r, s); adult head gray with different degrees of whitish edging on the labial scales, and a thin (1-2 scales long) white to light grayish brown irregular parietal collar; dorsal blotches incomplete ventrally, extending marginally onto ventrals but not fusing midventrally; (8) 215-907 mm SVL in males, 642-1187 mm in females; (9) 78-390 mm TL in males, 246-298 mm in females.

Comparisons.

Dipsas palmeri is compared to species previously subsumed under D. peruana : D. latifrontalis , D. klebbai (Fig. 1l, m), and D. peruana . From D. latifrontalis (Fig. 1n), it differs in having the first 19-35 dorsal blotches edged with white or cream, vs. the first 9-10 in D. latifrontalis . The only known adult of D. latifrontalis photographed in life has bronze interspaces (Fig. 1n), a coloration not seen in any adult of D. palmeri . From D. klebbai , it differs in having shorter blotches (longest blotch up to 3-7 vertebral scales long) that are circular (instead of oblong) and that are only longer than the interspaces on the first half of the body. From D. peruana , it differs in having dorsal blotches that are shorter than interspaces on posterior half of the body, and in lacking melanized interspaces in adult individuals.

Distribution.

Eastern slopes of the Ecuadorian and Peruvian Andes south of the Jatunyacu–Napo river valley in Ecuador and north of the Huancabamba depression at elevations between 1211 and 2282 m (Fig. 4).

Conservation status.

An estimated 31 out of the 42 known localities of occurrence for Dipsas palmeri are located within the limits or the buffer area of the following protected areas: Bosque Protector del Alto Nangaritza, Parque Nacional Llanganates, Parque Nacional Podocarpus and Parque Nacional Sangay. Furthermore, the presence of the species in degraded environments suggests a degree of tolerance for habitat modification. For these reasons, and because it does not meet the criteria for qualifying in a threatened category, we here list it as Least Concern following IUCN guidelines.

Remarks.

Neither Peters (1960) nor Harvey and Embert (2008) recognized the geographic morphological distinctiveness of Dipsas palmeri from Ecuador and Peru. Certainly, D. palmeri is most similar in coloration and lepidosis to D. latifrontalis (Fig. 1n) from Venezuela, and that is why Peters considered them synonyms. However neither Peters (1960) nor Harvey and Embert (2008) saw live specimens of D. latifrontalis in order to recognize the differences in life color pattern between the two species.

Two other junior synonyms of Dipsas peruana are D. latifasciata and D. polylepis , both of which occur in Peru (Fig. 4). Of these, only the latter must remain a synonym of D. peruana ; the former should be transferred to the synonymy of D. palmeri , as defined here. Examination of photographs of the specimen of D. latifasciata (BMNH 1946.1.2077) reveals this species has dorsal blotches shorter than interspaces on posterior half of the body, a character seen in D. palmeri but not in D. peruana . The holotype was collected by A. E. Pratt in "Upper Marañón”, with no further specific locality mentioned. However, the type locality can be restricted to the immediate environs of the town of Jaén, as the "Upper Marañón” is considered the segment of the Marañón river that goes from the town of Jaén until the river meets the Santiago River. Additionally, in a letter to his wife in 1913, the explorer explains how he crossed the Ecuadorian Andes and arrived at the town of Jaén in northern Peru, where he stayed and collected specimens for the BMNH before proceeding to Iquitos along the Marañón river, with no mention of visiting any locality east of the river at elevations where D. palmeri and D. peruana are known to occur. Harvey and Embert (2008) pointed out that the Huancabamba depression could be a geographic barrier separating species within the D. peruana complex, but they did not find evidence to support this view. Our results suggest that the Huancabamba depression is a major geographic barrier separating D. palmeri (north) from D. peruana (south).