systematics of snakes of the dipsas oreas complex - BioOne

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TABLE 4. STANDARD CHARACTERS FOR PERUVIAN SPECIMENS REFERRED TO DIPSAS GRACILIS COMPARED WITH A SAMPLE FROM ECUADOR. HEAD SCALES ARE SCORED AS INDICATED IN TABLE 1. BILATERAL COUNTS ARE SEPARATED BY A SOLIDUS (LEFT/RIGHT). N NUMBER OF SPECIMENS OR OBSERVATIONS; SVL SNOUT TO VENT LENGTH. Total length (SVL) (mm) Largest male Largest female Tail length/total length Male Female MUSM 2700 male MUSM 2701 male MUSM 17589 male Dipsas gracilis Ecuador 665 (471) 375 (275) — 760 (524) 727 (515) 0.29 0.27 — 0.30–0.33 0.32 0.01 (N 6) 0.29–0.31 0.30 0.01 (N 3) Maxillary teeth 18 — — 17 (N 1) 19 (N 1) 24 (N 2) Dorsal scales 15-15-15 15-15-15 15-15-15 15-15-15 Ventrals (and preventrals) Male Female Subcaudals Male Female Total segmental counts Male Female Anal scale Loreal pattern Preoculars Postoculars 187 (2 preventrals) — 104 — 291 — Single 1 1/1 2/2 189 (1 preventral) — 109 — 298 — Single 1 1/1 2/2 192 (1 preventral) — 94 — 286 — Single — — — 199–210 (1–5 preventrals) 203.8 3.97 (N 6) 194–199 (2–4 preventrals) 196.0 2.65 (N 3) 114–128 120.7 5.92 (N 6) 105–117 109.0 6.93 (N 3) 313–333 (N 6) 298–316 (N 3) Single 2(N 18) 0(N 18) 2(N 4) 3(N 14) Primary temporals 2/2 2/1 — 1 (N 1) 2(N 15) 3(N 2) Secondary temporals 3/3 2/2 — 2 (N 11) 3(N 7) 124 Bulletin Museum of Comparative Zoology, Vol. 158, No. 3
Dipsas oreas Complex in Ecuador and Peru • Cadle 125 TABLE 4. CONTINUED. Dipsas gracilis Ecuador MUSM 17589 male MUSM 2701 male MUSM 2700 male Tertiary temporals 4/3 3/3 — 0 (N 2) 3(N 14) 4(N 2) Supralabials (touching eye) 11 (5–7)/11 (5–7) 10 (4–6)/11 (4–7) — 8 (3–5) N 1 9 (3–5) N 3 9 (4–5) N 4 9 (4–6) N 2 10 (3–5) N 1 10 (4–6) N 7 Infralabials 13/13 13/13 — 10 (N 1) 11 (N 3) 12 (N 8) 13 (N 4) Number of infralabials in 1 pair 2 pairs 1 pair 1 pair (N 9) contact behind mental Number of bands or blotches on body 24 21 22 13–19 (N 9) uadorian border. The general region is arid in lower reaches of the valley to the west and subhumid toward the east. Relictual patches of humid forest still existed in the 1990s at higher elevations in montane regions in the eastern part of the valley (personal observations; see above notes on habitats of D. oreas in northern Peru). Dipsas gracilis is otherwise known only from the lowlands (1,000 m), whereas the only parts of the Río Quiroz valley presently having humid forest habitats are at higher elevations in the eastern part of the river system (2,000 m). The pattern elements visible in MUSM 2700–01 are similar to other specimens of Dipsas gracilis. The dorsal pattern consists of a series of dorsal blotches or bands, which, when viewed in lateral aspect, are oval on the anterior body and round posteriorly. The anterior bands nearly meet midventrally; posterior ones encroach onto the outer edges of ventrals. The top of the head is mainly dark blackish with light patches and flecks (more light patches are present in the smaller specimen, MUSM 2701). The vertebral scale row is greatly expanded (1.5–2 the width of the paravertebral rows). The three Peruvian specimens referred to Dipsas gracilis conform generally to other males of D. gracilis I examined, but there are differences from Ecuadorian specimens as well (Table 4). The Peruvian specimens have lower ventral (187–192) and subcaudal (94–109) counts than males from Ecuador (ventrals 199–210, subcaudals 114–128). MUSM 2700–01 have shorter tails and a different loreal pattern from Ecuadorian specimens. In D. gracilis from Ecuador, all the dorsal bands are complete across the venter (anterior body) or encroach very broadly onto the ventral scutes, nearly meeting midventrally (posterior body). This is the case in MUSM 17589, but in MUSM 2700–01, the posterior bands end on the outer edges of the ventral scutes. Although some scutellation characteristics of the three Peruvian specimens re-
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SYSTEMATICS OF SNAKES OF THE DIPSAS
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Dipsas oreas Complex in Ecuador and
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Dipsas oreas Complex in Ecuador and
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