Comprehensive DescriptionRead full entry
Scolecomorphus vittatus is a long caecilian with a long, slender head and a body that is slightly flattened dorsoventrally. Adults range from 141 mm to 376 mm (Nussbaum 2003); one author has reported a maximum length of over 400 mm (Gower et al. 2004) and one of 450 mm (Harper and Vonesh 2003). Body width is about 15 mm (Harper and Vonesh 2003). There are 120-148 primary annuli (Nussbaum 2003). A sample of 10 adult males and 10 adult females showed no evidence of sexual dimorphism (Jones et al. 2006), although at least one field guide refers to females being larger and having more annuli (Harper and Vonesh 2003). The body is somewhat tapered anteriorly (Gower et al. 2004). The skull is zygokrotaphic and the head shape is slightly compressed dorsoventrally (Gower et al. 2004). Stapes are absent, as is the case for all scolecomorphids (Loader et al. 2003). Although the orbit is covered by bone, eyes are relatively well-developed (Wake 1985) and are protrusible from the skull (Taylor et al. 1968; Nussbaum 1985; O'Reilly et al. 1996). Tentacles are long and slender, and are close to the snout tip, positioned on the underside of the snout and level with the mouth or anterior to the margin of the mouth (Gower et al. 2004; Loader et al. 2003). Palatine teeth extend posteriorly from the end of the maxillary tooth row rather than overlapping with the maxillary series (Gower et al. 2004). Adult scolecomorphids have three series of pointed and recurved monocuspid teeth: the premaxillary-maxillary andprevomeropalatine series in the upper jaw and the dentary series in the lower jaw. In S. vittatus the premaxillary-maxillary series has 14-25 teeth, the prevomeropalatine series has 9-21 teeth, and the dentary series has 17-31 teeth (Nussbaum 1985).
This species is brightly colored for a caecilian; it is not known whether the coloration is aposematic. The venter is bright red to pink. A dark stripe (black, dark brown, or purple) is present on the dorsum. The chin area is darker brown to pink. The vent area is pink or cream (Harper and Vonesh 2003).
A juvenile specimen has been described by Loader et al. (2003). This specimen was collected in 1973 in the North Pare Mountains, Tanzania, from a locality where the only known caecilian species is S. vittatus; it was dug out from rich, moist soil in a banana/coffee plantation. The specimen measured 72 mm in length, placing it as a juvenile; it is poorly ossified and may be a newborn. Environmental debris consisting of mineral and soil particles was found to be present in the hindgut. The juvenile specimen lacks secondary annuli and has a terminal shield and a longitudinal vent, as would be expected for Scolecomorphus. It also has a number of features that are not present in adult Scolecomorphus: paraoral processes on the cheeks that form lateral expansions of the upper jaws, border a ventral concavity on the snout, and also bear a few extraoral monocuspid teeth that lie outside of the mouth and point upward and outward; very flexible articulation of the mandible with the cranium; heterogeneous dentition with single rows of adult-like monocuspid teeth in addition to several supernumerary teeth (of which some are bicornute); and a concavity on the underside of the throat in the second nuchal collar, bordered by longitudinal ventrolaterally directed rostral ridges that terminate at the posterior margin of the second nuchal collar in what looks like a fleshy nipple. Although the presence of marginal tooth rows with larger adult-type teeth and smaller supernumerary teeth with occasional bicornute crowns is typical of newborns of other viviparous caecilians (Wake 1977), the extraoral teeth of this specimen are not of the "fetal type" and are located on the upper jaw, unlike any other caecilian specimen reported (Loader et al. 2003). The snout shape is somewhat different than that of adults, being more wedge-shaped with a more pointed snout tip than the bluntly rounded subconical snouts typical of adult scolecomorphids (Loader et al. 2003).
Scolecomorphus vittatus is the only known vertebrate with mobile, protrusible eyes (O'Reilly et al. 1996).