Atractus discovery, 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 discovery sp. nov.

Figs 3 , 4 , 5d Proposed standard english name: Discovery Ground Snake. Proposed standard spanish name: Culebra tierrera de Discovery.

Holotype.

ZSFQ 4937 (Figs 3 , 4 ), adult male collected by Alejandro Arteaga and Amanda Quezada at Amaluza, Azuay province, Ecuador (S2.61582, W78.56537; 2002 m).

Paratypes.

ZSFQ 4936 (Fig. 5d ), adult female collected by Alejandro Arteaga and Amanda Quezada at the type locality. MZUA.Re.466, adult female collected on 16 November 2018 at Campamento Arenales, Morona Santiago province, Ecuador (S2.59253, W78.56507; 2057 m).

Diagnosis.

Atractus discovery 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) one postocular; (3) loreal 2.5-3 × longer than high; (4) temporals 1+2; (5) eight supralabials, fourth and fifth contacting orbit; (6) seven infralabials, first four contacting chinshields; (7) six or seven maxillary teeth; (8) one row of gular scales; (9) three preventrals; (10) 168 ventrals in the male holotype (Fig. 3b ) and 170-172 ventrals in females; (11) 27 subcaudals in the male holotype and 17-18 subcaudals in females; (12) dorsal ground color light brown with faint stippling of a darker shade (Figs 3a , 5d ); (13) venter yellow with a brown ventral stripe (Fig. 3b ); (14) 284 mm SVL in the male holotype and 308-328 mm SVL in females; (15) 28 mm TL in the male holotype and 19-24 mm TL in females.

Comparisons.

Atractus discovery sp. nov. differs from most of its congeners by having a bright yellow belly with a conspicuous dark brown longitudinal stripe. This species is compared to other small brownish congeneric ground snakes distributed along the Amazonian slopes of the Andes (most of these are pictured in Fig. 5 ): Atractus avernus Passos et al., 2009b, A. duboisi , A. ecuadorensis , A. zgap sp. nov., A. occipitoalbus (Jan, 1862), A. orcesi , and A. resplendens . From A. avernus , A. duboisi , A. occipitoalbus , and A. orcesi , the new species differs in having 17/17/17 (instead of 15/15/15) dorsal scale rows. From A. ecuadorensis , A. zgap sp. nov., and A. resplendens , it differs in having a bright yellow belly with a conspicuous dark brown longitudinal stripe. From A. ecuadorensis and A. zgap sp. nov., it further differs by having one (instead of two) postocular scale (Fig. 4c ).

Description of holotype.

Adult male, SVL 284 mm, tail length 28 mm (9.9% SVL); body diameter 7.8 mm; head length 8.8 mm (3.1% SVL); head width 5.6 mm (2.0% SVL); interocular distance 3.4 mm; head slightly distinct from body; snout-orbit distance 3.4 mm; rostral 1.6 mm wide, ca. as broad as high; internasals 0.9 mm wide; prefrontals 2.1 mm wide; frontal 2.9 mm wide, with a curvilinear triangular shape in dorsal view; parietals 2.2 mm wide, ~ 2 × as long as wide; nasal divided; loreal 2.0 mm long, ~ 3 × longer than high; eye diameter 1.1 mm; pupil round; supraoculars 1.3 mm wide; one postocular; temporals 1+2, upper posterior temporal elongate; eight supralabials, fourth and fifth contacting orbit; symphysial 1.0 mm wide, ~ 2 × as broad as long and separated from chinshields by first pair of infralabials; seven infralabials, first four contacting chinshields; chinshields ~ 2 × as long as broad, posterior chinshields absent; four rows of gular scales; dorsal scales arranged in 17/17/17 rows, smooth without apical pits; two preventrals; ventrals 168; anal plate single; 27 paired subcaudals.

Natural history.

The three known specimens of Atractus discovery sp. nov. were found in open areas adjacent to cloud forest border. MZUA.Re.466 was crawling at ground level at around 7:30 pm. It was crossing a series of cement stairs. ZSFQ 4936 and ZSFQ 4937 were found during a cloudy day, buried 15-40 cm under soft soil at the border between the clearing of a graveyard, pastures, and remnants of native vegetation.

Distribution.

Atractus discovery sp. nov. is known only from two localities (Arena-les and Amaluza, listed under Suppl. material 1: Table S1) on each side of the Río Paute, in the Ecuadorian provinces Azuay and Morona Santiago, at elevations 2002-2057 m a.s.l. The airline distance between the two localities is 2.6 km (Fig. 2 ).

Etymology.

The specific epithet discovery is used as a noun in apposition and honors 'The Explorers Club Discovery Expedition Grants’ (https://www.explorers.org/grants) initiative, a program seeking to foster scientific understanding for the betterment of humanity and all life on Earth and beyond. The grant program supports researchers and explorers from around the world in their quest to mitigate climate change, prevent the extinction of species and cultures, and ensure the health of the Earth and its inhabitants. 'The Explorers Club Discovery Expedition Grants’ program funded the expedition that resulted in the discovery of this new species of snake.

Conservation status.

We consider Atractus discovery sp. nov. to be Data Deficient, following IUCN Red List criteria, because the species belongs to a poorly studied genus of snakes and is known only from three specimens collected recently in a single river valley ( Río Paute) in the Amazonian slopes of the Ecuadorian Andes. In addition to the presence of a system of major hydroelectric dams in this valley, most of the native cloud forest habitat in the segment between Amaluza and Arenales has been converted to pastures. However, we consider there is insufficient data to estimate whether this new snake species is restricted to the immediate environs of the type locality or if it is widely distributed along the unexplored cloud forests of the adjacent Sangay National Park.

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 3. Adult male holotype of Atractus discovery sp. nov. ZSFQ 4937 in a dorsal and b ventral view.

Figure 4. Head of the adult male holotype of Atractus discovery sp. nov. ZSFQ 4937 in a dorsal b ventral c lateral right, and d lateral left view.

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).