Dipsas jamespetersi (ORCÉS & ALMENDÁRIZ, 1989)
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Dipsas jamespetersi
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| Higher Taxa | Colubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) |
| Subspecies | |
| Common Names | |
| Synonym | Sibynomorphus petersi ORCÉS & ALMENDÁRIZ 1989 Sibynomorphus petersi — CADLE 2007: 216 Dipsas mikanii oreas — PARKER 1934: 271 Dipsas mikanii oreas — PARKER 1938: 444 Dipsas variegata variegata — PETERS 1964: 47 Sibynomorphus vagus — LEHR et al. 2002 Sibynomorphus petersi — WALLACH et al. 2014: 670 Dipsas jamespetersi — ARTEAGA et al. 2018 (nom. nov.) |
| Distribution | SW Ecuador, Peru Type locality: ‘‘Zhila (2, 250 m) 79°17’26”W, 03°39’45”S, parroquia Oña, cantón Girón, Provincia Azuay [Ecuador].’’ |
| Reproduction | oviparous |
| Types | Holotype: MEPN (also as EPN) 2659, adult male |
| Diagnosis | Diagnosis: Sibynomorphus petersi attains a large size (to 771 mm total length in females, 763 mm in males) and has moderately high ventral (164–188) and subcaudal (65– 87) counts. Many features distinguishing this species from others in Peru and Ecuador are aspects of color pattern. Sibynomorphus petersi has a dorsal ground color of medium brown (brown or grayish in preservative), generally with narrow, dark brown (sometimes dark gray in preservative), irregular zigzag crossbands that extend ventrally to the lowermost dorsal rows or extreme outer edges of the ventral scales (Figs. 13, 14). Three or four anterior crossbands are sometimes broader than the others. Crossbands may be fragmented into a dorsal and lateral series of blotches, and crossbands or blotches are difficult to discern in some individuals. The venter is whitish with bold black or dark brown squarish or half-moon–shaped blotches or streaks; the ventral ground color is sometimes heavily invested with brown, a reflection of a dense peppering of minute flecks and spots. The top of the head is brown or grayish brown with dark brown spots, streaks, or other markings in a highly irregular pattern. Nonetheless, one feature of the head pattern seems relatively constant, albeit somewhat variable in precise execution: a large discrete spot is usually present on each prefrontal scale (Fig. 15). The prefrontal spots are usually symmetrically placed but vary in size, shape, and exact position among specimens (see Color in Preservative and Variation in Pattern). They are usually round but occasionally are irregular in shape. Dark markings on the head have a narrow pale edge (yellowish in life), which can be obscure in preserved specimens. In many specimens the dark head markings also have a pale core (Fig. 15). Sibynomorphus petersi differs from other species of the genus in northern South America as follows: S. vagrans and S. vagus have fewer ventrals (149–159 and 144–158, respectively) and different color patterns (see descriptions and illustrations herein). Sibynomorphus oneilli usually has narrow, more or less straight-sided (compared with zigzag) crossbands and has fewer ventrals and subcaudals than S. petersi (S. oneilli ventrals and subcaudals, male: 152–168 and 62–77; female: 163–173 and 57–64). Sibynomorphus oligozonatus has anterior crossbands that are much broader than the interspaces and, in males, fewer ventrals (145–163) and subcaudals (66– 68); S. oligozonatus has six or seven supralabials, whereas S. petersi usually has eight. Sibynomorphus williamsi usually has six supralabials (3–4 touching the eye), whereas S. petersi usually has eight supralabials (4–5 touching the eye); S. williamsi also has distinct bold crossbands the entire length of the body and usually a relatively unmarked venter (when marked, never bold spots or half-moons). In the collections I surveyed, Sibynomorphus petersi was commonly misidentified as Dipsas variegata or D. oreas (see discussion of misidentifications in the literature below). Sibynomorphus petersi can be distinguished from all species of Dipsas in western Ecuador and Peru by a few key aspects of color pattern, especially details of the banding pattern on the body and patterns atop the head (see Cadle, 2005; Cadle and Myers, 2003). Scutellation characters alone are insufficient for some comparisons because of substantial overlap in scale counts for many species of Dipsadini. Species of Dipsas also have a relatively much larger eye than species of Sibynomorphus; see Cadle (2005) and Cadle and Myers (2003) for descriptions and illustrations. The following comparisons show, for subadult and adult S. petersi and D. oreas, the difference in eye size compared with SVL (for these comparisons subadults are <352 mm SVL): S. petersi: Adult eye size: 0.552 +/- 0.081% SVL (N = 4) Subadult eye size: 0.701 0.016% SVL (N =2) D. oreas: Adult eye size: 0.730 +/- 0.049% SVL (N=12) Subadult eye size: 0.840% SVL (N = 1) (Cadle 2007) Unfortunately we had to temporarily remove additional information as this was scraped by multiple AI companies who sell that data to their customers. These details, e.g. detailed descriptions or comparisons (about 6671 characters) are available for collaborators and contributors. Please contact us for details. |
| Comment | Not listed in Zoological Record. Some of the chresonyms listed under synonyms are actually misidentifications fide CADLE 2007. Diet: primarily molluscs (T. de Lema, pers. comm., 16 Oct 2015). Distribution: See map in Cadle 2007: 229 (Fig. 25), Cadle 2007: 253 (Fig. 43). Habitat: fully arboreal (Harrington et al. 2018). Similar species / Misidentifications of Sibynomorphus petersi in the Literature. “Sibynomorphus petersi was frequently misidentified in museum collections. Parker (1934: 271; 1938: 444) identified specimens of S. petersi from the collections of Clodoveo Carrión from southern Ecuador as Dipsas mikanii oreas (= D. oreas). Parker cited only six specimens from the Carrión collection as this species, whereas I located 13 Carrión specimens in the BMNH that were originally identified as ‘‘Dipsas mikanii oreas.’’ All of these except one are here referred to S. petersi (the other is S. oligozonatus; see Specimens Examined and Locality Records). Three specimens can, with reasonable confidence, be associated with BMNH catalogue numbers on the basis of the sex, locality, and segmental counts provided by Parker (1938): a male and two females from ‘‘Catamayo Valley’’ are, respectively, BMNH 1935.11.3.110 (=Sibynomorphus petersi), 1935.11.3.108 (=S. oligozonatus), and 1935.11.3.109 (= S. petersi). I could not confidently associate BMNH numbers with the other three specimens reported by Parker (1934, 1938). Specimens of Sibynomorphus petersi were commonly misidentified as Dipsas variegata, apparently on the basis of earlier reports of that species from Ecuador and Peru (e.g., Peters, 1960, 1964). However, Cadle and Myers (2003) showed that some previously published records of ‘‘Dipsas variegata variegata’’ and ‘‘Dipsas variegata nicholsi’’ from Ecuador and Peru were based on misidentifications of other species, including D. andiana, D. oreas, D. peruana, and S. petersi.10 Peters’ (1964: 47) record of ‘‘Dipsas variegata variegata’’ from western Ecuador is based on USNM 237040, which was subsequently referred to Sibynomoorphus petersi (Cadle and Myers, 2003: 7). Lehr et al. (2002) referred two specimens of S. petersi, SMF 80048 and MUSM 20583 from Ancash Department, Peru, to S. vagus. They clearly are not that species and one of them is here referred to S. petersi (see footnote 22).” (Cadle 2007) |
| Etymology | Named after James A. Peters (1922-1972), American herpetologist, specializing on South American reptiles. |
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