Atractus zgap, Arteaga & Quezada & Vieira & Guayasamin, 2022

Arteaga, Alejandro, Quezada, Amanda, Vieira, Jose & Guayasamin, Juan M., 2022, Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach, ZooKeys 1121, pp. 175-210 : 175

Atractus zgap sp. nov.

Figs 5g , 6 , 7 Proposed standard English name: ZGAP Ground Snake. Proposed standard Spanish name: Culebra tierrera de ZGAP.

Holotype.

ZSFQ 4946 (Figs 5g , 6 , 7 ), adult female collected by Diego Piñán at Santa Rosa , Napo province, Ecuador (S0.31004, W77.78591; 1500 m).

Paratypes.

MZUTI 5311, adult female collected by Diego Piñán in February 2017 at El Chaco, Napo Province, Ecuador (S0.31004, W77.78591; 1500 m). QCAZ 12666, a juvenile collected by Pablo Medrano on 16 May 2014 at San Francisco de Borja, Napo province, Ecuador (S0.40953, W77.84005; 1703 m). QCAZ 5183, a juvenile collected by Patricia Bejarano on 13 November 2011 at Bosque Protector "La Cascada," Napo province, Ecuador (S0.14572, W77.49593; 1460 m).

Diagnosis.

Atractus zgap sp. nov. is placed in the genus Atractus , as diagnosed by Savage (1960), based on phylogenetic evidence (Fig. 1 ). The species is diagnosed based on the following combination of characters: (1) 17/17/17 smooth dorsals; (2) two postoculars; (3) loreal 2 × longer than high; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first three contacting chinshields; (7) seven maxillary teeth; (8) three rows of gular scales; (9) two or three preventrals; (10) 173-177 ventrals in females; (11) 31 subcaudals in an uncollected male and 25-27 subcaudals in females; (12) dorsal ground color brown with faint dark longitudinal lines (Figs 5g , 6a ); (13) venter yellow with fine brown stippling (Fig. 6b ); (14) 376 mm SVL in the female holotype; (15) 37 mm TL in the female holotype.

Comparisons.

Atractus zgap sp. nov. is compared to other small brownish congeneric ground snakes distributed along the Amazonian slopes of the Andes (most of these are illustrated in Fig. 5 ): Atractus avernus , A. duboisi , A. discovery sp. nov., A. ecuadorensis , A. occipitoalbus , A. orcesi , and A. resplendens . From A. avernus , A. duboisi , A. occipitoalbus , and A. orcesi , the new species differs in having 17/17/17 dorsal scale rows. From A. discovery sp. nov., the new species differs in having two postocular scales (Fig. 7c ) and no dark ventral stripe. From A. ecuadorensis , the new species differs in having fewer (31 instead of 41) subcaudals in males, seven (instead of five or six) infralabials, a shorter (2 × instead of 3 × longer than high) loreal, frontal longer than prefrontals, and five faint (instead of six or seven clearly defined) longitudinal black lines (Figs 5g , 6 ). From A. resplendens , the new species differs in having a shorter (2 × instead of 3 × longer than high) loreal, two (instead of one) postoculars, and a brownish dorsum with faint longitudinal black lines, whereas in A. resplendens the dorsum is dark gray with fine yellow stippling (Fig. 5b ).

Description of holotype.

Adult female, SVL 376 mm, tail length 37 mm (9.8% SVL); body diameter 9.1 mm; head length 11.7 mm (3.1% SVL); head width 6.4 mm (1.7% SVL); interocular distance 4.3 mm; head slightly distinct from body; snout-orbit distance 3.8 mm; rostral 2.5 mm wide, ca. as broad as high; internasals 1.3 mm wide; prefrontals 2.5 mm wide; frontal 3.1 mm wide, with a curvilinear triangular shape in dorsal view; parietals 2.4 mm wide (56% length); nasal divided; loreal 1.6 mm long, ~ 2 × longer than high; eye diameter 1.7 mm; pupil round; supraoculars 1.2 mm wide; two postoculars; temporals 1+2; seven supralabials, third and fourth contacting orbit; symphysial 1.7 mm wide, ~ 2 × as broad as long, separated from chinshields by first pair of infralabials; seven infralabials, first three contacting chin shields; chinshields ~ 2 × as long as broad, posterior chinshields absent; dorsal scales arranged in 17/17/17 rows, smooth without apical pits; two preventrals; ventrals 173; anal plate single; 25 paired subcaudals.

Natural history.

Most individuals of Atractus zgap sp. nov. have been found during the day hidden under rocks, among herbs, or buried under soft soil in plantations and rural gardens close to remnants of native forest. At night, they have been seen crossing rural roads. Occasionally, during sunny days right after a rain, individuals have been seen crawling on the pavement or on gravel roads (Diego Piñán, pers. comm.).

Distribution.

Atractus zgap sp. nov. is known only from five localities (See Suppl. material 1: Table S1) along the valley of the Río Quijos, Napo province, in the Amazonian slopes of the Andes in northeastern Ecuador, at elevations 1460-1703 m a.s.l. (Fig. 2 ).

Etymology.

The specific epithet zgap is used as a noun in apposition and honors the 'Zoological Society for the Conservation of Species and Populations’ (ZGAP) (https://www.zgap.de), a program seeking to conserve unknown but highly endangered species and their natural habitats throughout the world. The ZGAP grant program supports the fieldwork of young scientists who are eager to implement and start conservation projects in their home countries. Specifically, ZGAP has supported the work on endangered Andean reptiles in Ecuador conducted by AA and JV.

Conservation status.

We consider Atractus zgap sp. nov. to be Endangered following the IUCN criteria B2a, b (i, iii) ( IUCN 2001), because the species’ extent of occurrence is estimated to be less than 500 km2 (Fig. 2 ) and its habitat is severely fragmented and declining in extent and quality due to deforestation. The valley of the Río Quijos formed the eastern frontier of the Incan Empire (1400-1532) and the cloud forest in the area suffered from intensive land-use even before European arrival ( Loughlin et al. 2018). Today, this valley is one of the most important cattle farming areas along the eastern slopes of the Andes and the majority of the forest along the Quijos river plains has been destroyed. Although A. zgap occurs in one protected area (Bosque Protector "La Cascada") and its presence is expected in adjacent Parque Nacional Cayambe-Coca and Parque Nacional Sumaco Napo-Galeras, it has so far not been recorded in major protected areas.

Figures

Figure 1. Phylogenetic relationships within Atractus inferred using a Bayesian inference and derived from analysis of 3,985 bp of DNA (gene fragments 16 S, CYTB, ND 4, C-MOS, NT 3, and RAG 1). Support values on intra-specific branches are not shown for clarity. Voucher numbers for sequences are indicated for each terminal. Black dots indicate clades with posterior probability values from 95 - 100 %. Grey dots indicate values from 70 - 94 %. White dots indicate values from 50 - 69 % (values <50 % not shown). Colored clades correspond to the species' distribution presented in the map of Fig. 2. New or resurrected species are indicated in bold type.

Figure 2. Distribution of Atractus arangoi, A. roulei, A. michaelsabini sp. nov., A. zgap sp. nov., and A. discovery sp. nov. in Ecuador and adjacent Colombia. White dots represent localities listed under Suppl. material 1. Each colored area is a geographic representation of the suitable environmental conditions for one of the clades recovered in the phylogeny of Fig. 1.

Figure 5. Photographs of living specimens of brown-colored Atractus occurring along the Amazonian slopes of the Andes in Ecuador a A. arangoi ZSFQ 4948 from Jatun Sacha Biological Reserve, Napo province, Ecuador b A. resplendens ZSFQ 4953 from Montanas de San Antonio, Tungurahua province, Ecuador c A. duboisi from Orito Yacu, Napo province, Ecuador d A. discovery sp. nov. ZSFQ 4936 from Amaluza, Azuay province, Ecuador e A. orcesi ZSFQ 2234 from El Higueron, Sucumbios province, Ecuador f A. pachacamac from Nangaritza, Zamora Chinchipe province, Ecuador g A. zgap sp. nov. ZSFQ 4946 from Santa Rosa, Napo province, Ecuador h A. occipitoalbus JMG- 2077 from Macas, Morona Santiago province, Ecuador i A. major from Jatun Sacha Biological Reserve, Napo province, Ecuador; and j A. major from Reserva Natural Palmari, Amazonas state, Brazil (photo by Sebastian Di Domenico).

Figure 6. Adult female holotype of Atractus zgap sp. nov. ZSFQ 4946 in a dorsal and b ventral view.

Figure 7. Head of the adult female holotype of Atractus zgap sp. nov. ZSFQ 4946 in a dorsal b ventral c lateral right, and d lateral left view.