Atractus touzeti, Schargel, Walter E., Lamar, William W., Passos, Paulo, Valencia, Jorge H., Cisneros-Heredia, Diego F. & Campbell, Jonathan A., 2013

Schargel, Walter E., Lamar, William W., Passos, Paulo, Valencia, Jorge H., Cisneros-Heredia, Diego F. & Campbell, Jonathan A., 2013, A new giant Atractus (Serpentes: Dipsadidae) from Ecuador, with notes on some other large Amazonian congeners, Zootaxa 3721 (5), pp. 455-474 : 466-469

Atractus touzeti sp. nov.

Figs. 6 and 7

Holotype. Adult female, FHGO 517, collected dead on road on 16 August 1992 by Peter Pearman at Cosanga– Archidona road (00°37’S, 77°48’W; 2200 m) in the Cordillera de Los Guacamayos, Province of Napo, Ecuador.

Paratypes. Two adult females, FHGO 2035 and FHGO 2036, collected dead on road on 5 April 1998 by Felipe Campos at La Virgen (ca. 2000 m) in the Cordillera de Los Guacamayos, Province of Napo, Ecuador.

Diagnosis. A species of Atractus with 17 dorsal scales rows differing from all other members of the genus by the following combination of characters: (1) large size and thick body, adults reaching more than 1000 mm in TL; (2) loreal long (about three times longer than high); (3) eight supralabials, four and five in contact with eye; (4) seven or eight infralabials; (5) eight maxillary teeth; (6) 167–170 ventral scales in females; (7) Tail of moderate length Tail/TL 9.5–11.4%; (8) 31 subcaudal scales in females; (9) dorsal color pattern of short pale crossbands edged by black borders that separate the pale color from the brown ground color.

Comparisons. Regarding all known species of Atractus with 17 dorsal scales, only A. gigas , A. latifrons , A. major , A. obesus , A. sanctamartae , A. serranus , A. snethlageae , A. titanicus , A. torquatus , A. trihedrurus , and A. zebrinus attain a TL close to or exceeding 600 mm. Adults of A. serranus and A. trihedrurus have a uniform dorsum, but they also differ from A. touzeti in having fewer ventrals (<164) and subcaudals (<24). In both A. latifrons and A. torquatus there is a single postocular whereas there are two in A. touzeti . Atractus torquatus further differs from the new species in having a cream venter with well-spaced small spots or nearly immaculate whereas in A. touzeti the venter is heavily pigmented with large, roughly rectangular or irregular blotches. Atractus latifrons further differs from A. touzeti in having a color pattern of rings that encircle the whole body. Atractus major , A. obesus , A. sanctamartae , A. titanicus , and A. zebrinus all have seven supralabials. Atractus sanctamartae , A. titanicus and A. zebrinus further differ from A. touzeti in having fewer subcaudals (>28). Atractus major and A. obesus further differ from A. touzeti in aspects of dorsal coloration with A. major having a pattern of pale-edged dark brown blotches or bands, while A. obesus has black rings that encircle the body.

Among the large species of the genus Atractus touzeti is most similar to A. gigas and A. snethlageae . Atractus gigas is the only species in the genus that is really comparable in size and habitus to A. touzeti , but adults of the former species are either uniform or with inconspicuous pale bands dorsally whereas the dorsal crossbands in A. touzeti are conspicuous and well-defined. All three specimens of A. touzeti have eight supralabials whereas specimens of A. gigas typically have six or seven supralabials (see Passos et al. 2010b). The number of infralabials that contact the chinshields on each side is four in the two paratypes of A. touzeti but the holotype is asymmetric and has four on one side and three on the other; all specimens of A. gigas have three infralabials in contact with the chinshields. Atractus snethlageae is a smaller species that is not known to reach a TL of over 718 mm, it has six to seven maxillary teeth (eight in A. touzeti ), and typically seven infralabials (eight in A. touzeti ). The maximum number of subcaudals observed (including data from Cunha and Nascimento, 1983) in females of A. snethlageae is 28, whereas all three specimens of A. touzeti have 31 subcaudals. Although it is possible that the range of subcaudals of these two species will overlap when more specimens of A. touzeti are obtained, it is obvious that they differ in typical values for this character. These two species also differ in other aspects of morphometrics as explained in the results section; specifically the HW/HL ratio seems to be a useful character for separating them. Among small species of Ecuadorian Atractus (<50 cm TL), all of them except A. multicinctus have dorsal color patterns other than crossbands, usually being striped, spotted or uniformly colored. Atractus multicinctus further differs from A. touzeti by having fewer maxillary teeth (5 or 6) and supralabials (7).

Description of the holotype. An adult female, 1195 mm in TL, tail length 114 mm (9.5% of TL); head slightly distinct from neck, as wide as long (HW: 28.8 mm; HL: 28.6 mm). Snout truncated in dorsal view, rounded in lateral view; eye moderately small (2.9 mm), about same size as the upper postocular, pupil circular; eye-nostril distance 0.29 of HL; 2.8 times eye diameter; rostral bell-shaped, barely visible in dorsal view, 1.6 times broader than high, lingual groove reduced; internasals small, as long as wide, laterally contacting anterior and posterior nasals; prefrontals large, 1.2 times longer than wide, in contact with eye; frontal roughly triangular, 1.2 longer than wide, 1.5 times longer than median suture of prefrontals; parietals 1.6 times longer than wide, median suture of parietals 0.8 times length of frontal. Nasal divided, posterior scale twice the size of the anterior; preocular absent; loreal 2.5 times longer than high, narrowly touching the eye, anterior edge 2.2 times higher than posterior; two postoculars, lower very small, upper 6 times larger; temporals 1 + 2, upper posterior temporals elongated, as large as the frontal; supralabials eight on both sides, first contacting nasals, second contacting posterior nasal and loreal, third and fourth contacting loreal, fourth, fifth and sixth in contact with eye on the right side, fourth and fifth in contact with eye on left side, sixth contacting postocular and anterior temporal, seventh contacting anterior and posterior temporals, eighth contacting posterior temporal and dorsals; infralabials eight on the right side seven on the left, four contacting the chinshields on right side, three on left side, first pair short, meeting at ventral midline, separating mental from chinshields; one pair of chinshields, each 2.3 times longer than wide. Maxillary teeth eight, most teeth bearing a prominent longitudinal ridge on the labial side; palatine teeth large; dorsal scales in 17–17–17 rows, smooth without apical pits; ventrals 170, preventrals four; anal plate single; subcaudals 31, paired.

Color pattern of the holotype. In preservative (alcohol 70% after formalin), the dorsal ground color is hair brown with dark and cream mottling on dorsal scale rows 1–3; there are 34 dorsal crossbands along the body, seven on the tail, extending laterally to the first dorsal scale row except for the first two which extend to dorsal scale row six (blotches). The crossbands are tawny olive, one dorsal scale long, edged by black borders of about the same length, separated from each other by two to three dorsal scale lengths, they become indistinct and darkly mottled on the first and/or second dorsal scale rows; they alternate with small lateral blotches of the same color that cover partially the first and second dorsal scale rows on each side. The dorsum of the head is olive brown, slightly paler than the dorsum of the body, with some inconspicuous dark brown spots; an incomplete short dark band is present in the nuchal region. Supralabials have cream spots with dark mottling in the lower portion. Infralabials, mental and chinshields are mostly dark brownish olive with cream spots. The venter is cream heavily pigmented with large rectangular and irregular dark brownish olive blotches.

Variation. The two paratypes are adult females with TL of 1050 and 1030 mm, and tail lengths of 120 and 115 mm, respectively comprising 11.4 and 11.2% of TL. The cephalic index (width/length x 100) is 101–120 (mean = 114, n = 3). There are eight supralabials (both sides) with the fourth and fifth entering the orbit in both specimens; infralabials are eight in FHGO 2035 and seven (right side) and eight (left side) in FHGO 2036, with four in contact with the chinshields. In the paratypes the upper posterior temporal is not as large as in the holotype, and is about the same size as the first temporal. The upper postocular is about twice the size of the lower postocular in both specimens. There are 169 and 167 ventrals and 31 subcaudals in the paratypes. Other aspects of lepidosis agree well with the holotype. Both paratypes have eight maxillary teeth on the right side, reducing in size posteriorly. Palatine and pterygoid teeth in FHGO 2035 are seven and five, respectively, on each side. We could not count teeth in the other specimens because of damage to dentigerous bones (FHGO 2036) or the specimen was sufficiently brittle as to preclude opening the mouth without risking breaking the jaw (holotype). The numbers of dorsal crossbands in the paratypes are 34 and 32 along the body, and seven and eight on the tail, respectively. In the holotype the percentage of the venter covered with dark blotches is almost 50%; in the paratypes this percentage is lower, about 35–40%, and the color of the blotches is dark neutral gray.

Color in life. Although we do not have notes about the color in life of the type series of A. touzeti , we have received a picture taken in situ of a live individual found in the same locality from which the paratypes were obtained. The specimen was found crossing a road and was not collected but its large size and robust habitus are apparent in the picture. The background color of the dorsum is dark brown (darker tone than what was observed in the preserved specimens), becoming almost black towards the middorsal region. The crossbands are conspicuous and bright yellow on the side but become suffused with brown color towards the middorsal region. The black borders of the crossbands are not distinct in this specimen. There are about 42 crossbands total from neck to tail.

Etymology. We take great pleasure in naming the new species after Jean-Marc Touzet, an enthusiastic promoter of herpetology in Ecuador and the founder of the Fundación Herpetológica Gustavo Orcés.

Distribution. Known only from the Cordillera de Los Guacamayos in the Eastern Andean range of Ecuador ( Fig. 8 ). According to the recent classification of ecosystems in Ecuador (Ministerio del Ambiente de Ecuador, 2013) the area where the type locality is located is part of the “evergreen montane forest of the north and central Cordillera Oriental of the Andes.” The vegetation in this ecosystem is constituted mostly by evergreen forests reaching 20-25 m in height, dominated by Andean species in the families Melastomataceae (Miconia) , Solanaceae , Myrsinaceae , Aquifoliaceae , Araliaceae , Rubiaceae and several families of ferns. Valencia (1995) studied the composition and structure of a forest near Baeza (2000 m), Napo, Ecuador, which is about 20 km north of the type locality of A. touzeti and found that the vegetation was composed of a combination of typical Amazonian and Andean species, with trees reaching 30 m tall and the understory being dominated by the palm tree Geonoma undata .

Figures

FIGURE 7. Dorsal (top) and lateral (bottom) view illustrations of the head of the holotype (FHGO 517) of A. touzeti.

FIGURE 8. Map of Ecuador indicating type locality (solid circle) of A. touzeti. The two localities in which the species has been collected are nearby and cannot be separated on the map.