Dipsas oswaldobaezi, 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

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 : 93-95

Dipsas oswaldobaezi sp. n. Figs 13, 14

Sibynomorphus oligozonatus Cadle, 2007: 195 (part).

Proposed standard English name.

Oswaldo Báez’ Snail-Eater

Proposed standard Spanish name.

Caracolera de Oswaldo Báez

Holotype.

QCAZ 10369 (Fig. 13), adult female collected by Silvia Aldás and Gabriel Zapata on March 03, 2010 at Quebrada El Faique, province of Loja, Ecuador (S4.17889, W80.04226; 1004 m).

Paratypes.

BMNH1935.11.3.108, adult female collected by Clodoveo Carrión in the valley of Catamayo, province of Loja, Ecuador (S3.98064, W79.35928; 1289 m). MUSM 2192, adult male collected by Otavio Ruíz in Piura (department or city not specified), Peru. MZUA.RE.0286, adult of undetermined sex collected by Valentina Posse on December 2015 at Huaquillas, province of El Oro, Ecuador (S3.54115, W80.08646; 39 m). QCAZ 14051, adult of undetermined sex collected by Paul Székely and Diana Székely on March 18, 2015 at Reserva Ecológica Arenillas, province of El Oro, Ecuador (S3.62110, W80.17513; 41 m). QCAZ 14060, adult of undetermined sex collected by Paul Székely and Diana Székely on June 16, 2015 at Guabillo, province of El Oro, Ecuador (S3.60346, W80.18139; 44 m). QCAZ 15108, adult female collected by Diego Almeida, Darwin Núñez, Eloy Nusirquia, Santiago Guamán and Guadalupe Calle on November 12, 2016 at Reserva La Ceiba-Pilares, province of Loja, Ecuador (S4.27502, W80.32805; 534 m) (Fig. 14).

Diagnosis.

Dipsas oswaldobaezi is placed in the genus Dipsas based on phylogenetic evidence (Fig. 3) and the absence of a labial that is noticeably higher than other labials and in contact with the postocular, primary and secondary temporals. The species differs from all described species of Dipsas based on the following combination of characters: (1) 15/15/15 smooth dorsals with a slightly enlarged vertebral row (1-1.2 times as wide as adjacent rows); (2) loreal and prefrontal in contact with orbit; (3) six supralabials with 3rd and 4th contacting orbit; (4) no infralabials in contact behind symphysial; (5) 163-179 ventrals in males, 177-179 in females; (6) 68-70 divided subcaudals in males, 65-66 in females; (7) dorsal ground color light sandy brown with a pattern of 55-63 drab to brown black-edged middorsal blotches that are wider (7-9 vertebral scale rows) and solid down to the edges of the ventrals on the first one third of the body, but becoming narrower (1-3 vertebral scales long) and broken up laterally towards the tail; interspaces finely speckled with brown pigment; ground color of the head light sandy brown with a thin light cream nuchal collar and bold dark brown to black irregular blotches scattered on head plates and edging supralabials; ventral surfaces sandy brown with fine black speckling (Fig. 13b); iris sandy brown with dense dark brown speckling; (8) 277-348 mm SVL in males, 407-428 mm in females; (9) 85-114 mm TL in males, 110-122 mm in females.

Comparisons.

Dipsas oswaldobaezi is most similar to D. williamsi , D. georgejetti , D. oligozonata , and D. vagrans , in that order, all of which were previously included in the genus Sibynomorphus . From D. williamsi , it differs in having 7-9 infralabials (vs. 10 in D. williamsi ), first supralabial not in contact with prefrontal (vs. in broad contact in D. williamsi ), and dorsal blotches that are lighter in the middle (vs. dark solid blotches). From D. georgejetti (Figs 11, 12), it differs in having 6 supralabials with 3rd and 4th bordering the eye (vs. 7 supralabials with 4th and 5th bordering the eye in D. georgejetti ). From D. oligozonata (Fig. 1o) and D. vagrans , it differs in having more than 160 ventrals. Dipsas oswaldobaezi further differs from D. oligozonata in having distinct bold crossbands at least middorsally along the whole length of the body, instead of being present only on the anterior half of the body. Genetic divergence in a 529 bp long fragment of the mitochondrial Cytb gene between D. oswaldobaezi and D. williamsi is 4.0-4.2%, whereas intraspecific distances are less than 0.2% in D. williamsi . For the same fragment, the distance between D. oswaldobaezi and D. georgejetti is 8.3%.

Description of holotype.

Adult female, SVL 277 mm, tail length 85 mm (31% SVL); head length 9.5 mm (3.4% SVL) from tip of snout to commissure of mouth; head width 7.3 mm (76% head length) taken at broadest point; snout-orbit distance 3.3 mm; head distinct from neck; snout short, blunt in dorsal and lateral outline; rostral 2.1 mm wide, broader than high; internasals 1.2 mm wide, broader than long; prefrontals 2.2 mm wide, slightly broader than long and contacting orbit; supraocular 2.6 mm long, longer than broad; frontal 2.9 mm long, pentagonal, in contact with prefrontals, supraoculars, and parietals; parietals 4.2 mm long, longer than broad; nasal not divided, in contact with first supralabial, loreal, prefrontal, internasal, and rostral; loreal 1.3 mm long, longer than high, entering orbit; eye diameter 2.2 mm; pupil semi-elliptical; no preocular; two postoculars; temporals 2+2; 6 supralabials, 3rd and 4th contacting orbit; symphysial separated from chinshields by the first pair of infralabials; 9/8 (right/left) infralabials, 1 –6/1– 5 contacting chinshields; both pairs of chinshields longer than broad; dorsal scales in 15/15/15 rows, smooth, without apical pits; 179 ventrals; 70 divided subcaudals; cloacal plate single.

Natural history.

Individuals of Dipsas oswaldobaezi have been found active by night on vegetation or at ground level in forested environments, pastures, or rural gardens. One individual (QCAZ 15108) was found hidden under leaf litter during daytime. Two individuals (MZUA.RE.0286 and QCAZ 14060) were found dead on roads.

Distribution.

Deciduous and semideciduous lowland to lower montane forests and dry lowland shrublands in southwestern Ecuador (provinces of Loja and El Oro) and northwestern Peru (department of Tumbes), at elevation between 39 and 1289 m (Fig. 5).

Etymology.

The specific name oswaldobaezi honors Dr. Oswaldo Báez, a renowned Ecuadorian biologist and researcher who has dedicated his life to the teaching of science, scientific thinking, and the conservation of nature. Oswaldo Báez has played a major role in science education in Ecuador through many popular science articles and books.

Conservation status.

We consider Dipsas oswaldobaezi to be Vulnerable following the IUCN criteria B1a,b(iii, iv) (IUCN 2001) because its extent of occurrence is estimated to be 8,605 km2; it is known only from eight localities effectively corresponding to four patches of forest lacking connectivity between them, and its habitat is severely fragmented and declining in extent and quality due to deforestation.

Remarks.

In his revision of Dipsas oligozonata , Cadle (2007) allocated three additional specimens (AMNH 110587, BMNH 1935.11.3.108 and MUSM 2192) to a species known only from the holotype (EPN 3612), collected at Zhila, province of Azuay (S3.50280, W79.18808; 2795 m) (Fig. 5). AMNH 110587 was collected ca. 34 km airline distance from the type locality at an elevation of 2204 m, and it resembles the holotype in both color and lepidosis. However, BMNH 1935.11.3.108 and MUSM 2192 have more than 160 ventral scales and have broad dark brown crossbars that are at least twice as long as those present in both the holotype, AMNH 110587 and in the other four specimens of D. oligozonata examined by us (Table 2; Fig. 1o), all of which have fewer than 160 ventral scales and come from elevations between 2102 and 2891 m in the watershed of the Río Jubones (Fig. 5). The coloration and ventral scale counts in BMNH 1935.11.3.108 and MUSM 2192 are more similar to D. oswaldobaezi , and we designated them as paratypes of this species.