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Tropidophiinae: Superficially, Dwarf Boas are intermediate between colubrids and boas. Cranially, they have two common carotid arteries, edentulous premaxillaries, longitudinally oriented maxillaries with solid teeth, and optic foramina that perforate the frontal-parietal sutures. The coronoid is reduced or absent, and the dentary bears numerous teeth. Hindlimb vestiges appear externally as cloacal spurs in males, and pelvic remnants occur in the trunk musculature except in Tropidophis semicinctus (and Xenophidion). Intracostal arteries arise from the dorsal aorta at nearly every trunk segment or at intervals of several segments. In contrast to related boids they have no or a substantially reduced left lung (in Ungaliophis); a tracheal lung is well developed. Both left and right oviducts are well developed too (modified after Zug et al. 2001). |
