systematics of snakes of the dipsas oreas complex - BioOne

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82 Bulletin Museum of Comparative Zoology, Vol. 158, No. 3 Figure 3. Female paralectotype of Dipsas ellipsifera (BMNH 1946.1.21.28; 488 mm SVL). condition and has a color pattern and general characteristics typical of all specimens of Dipsas ellipsifera examined. In addition to details reported for the lectotype in Table 2, it is worth noting that the dorsal formula of 16-15-15 is a variation occasionally observed within Dipsas. The lectotype has a relatively longer tail (27% of total length) than other specimens of D. ellipsifera examined. Comments concerning the color patterns of the syntypes are given in the section on coloration below. Diagnosis Dipsas ellipsifera is characterized by a low number of ventrals (153–164 in seven males, 157–158 in two females) and subcaudals (72–78 in males, 62–63 in females). Its color pattern consists of 30 to 40 markings, each of which has a characteristic composition. Each marking typically appears as a closely spaced pair of black bars or bands with a central whitish area (Figs. 2–5, 7); edges of the markings are more or less vertical. The markings may be continuous across the vertebral region, forming complete bands, or contralateral markings may fail to meet in the vertebral region, forming a series of lateral bars. The anterior five or six markings are broader than more posterior ones and are Figure 4. Dipsas ellipsifera (Boulenger). Dorsal and ventral views of UMMZ 83700, an adult from Pimampiro, Ecuador (349 mm SVL). equivalent to, or broader than, the light interspaces. Posterior markings are narrower than the interspaces. Dipsas ellipsifera differs from all other species of Dipsas in western Ecuador by its low number of ventrals and subcaudals and additionally differs from all species except D. elegans in color pattern (see Table 1 and the key accompanying this report). Dipsas andiana, D. gracilis, and D. temporalis all have 180 ventrals, 80 subcaudals, and patterns that do not involve narrow bands or bars with light centers. Dipsas oreas has 165 ventrals, 65 subcaudals, and a different color pattern (see below). Additional commentary is warranted concerning the most similar spe-
Dipsas oreas Complex in Ecuador and Peru • Cadle 83 Figure 5. Dipsas ellipsifera (Boulenger). Dorsal views of representative adult specimens from Pimampiro, Ecuador. Top: UMMZ 83697 (386 mm SVL). Bottom: UMMZ 83698 (357 mm SVL). cies, D. elegans, in view of their similar color patterns and the previous confusion of the two species (e.g., Kofron, 1982; Peters, 1960a). The distinctions are most clearly seen by separately comparing the sexes. Dipsas ellipsifera differs from D. elegans (see Table 1) in having fewer ventrals (D. elegans: 177–189 in males; 166–178 in females) and subcaudals (D. elegans: 94–105 in males; 68–88 in females), a smaller relative eye size, and a differently shaped head (Figs. 6, 10). The head of adult D. ellipsifera is small relative to body size and has rounded canthal and temporal regions, whereas the head of adult D. elegans is larger, blocky, and has angular canthal and temporal regions. On the basis of a few Figure 6. Head patterns of Dipsas ellipsifera (Boulenger). Top: UMMZ 83697. Middle and bottom: UMMZ 83698 (dorsal and lateral). Both specimens from Pimampiro, Ecuador. observations for D. ellipsifera, it seems that small juveniles of this species (210 mm snout–vent length [SVL]) already manifest the adult color pattern (e.g., Fig. 7), whereas small juveniles of D. elegans (Figs. 11, 12) have solid dorsal bands that only develop light centers somewhat later
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Dipsas oreas Complex in Ecuador and
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