PHALLUS MORPHOLOGY IN CAECILIANS 



149 



the literature and warrants further histological examination. Tonutti 

 ( 1 93 1 , 1 933) viewed the longitudinal ridges as encompassing longi- 

 tudinal 'propulsor' muscles but we are unable to verify this from his 

 figured sections. Wake (1972: 354) described the ridges as 'longitu- 

 dinal muscles overlain by fibrous connective tissue', but also warned 

 (p. 363) that 'Caution must be exercised in interpreting the various 

 folds in the cloacal wall. They may often not be muscle but may be 

 ridges of connective tissue'. Wake (1998) referred to connective 

 tissue ridges in Scolecomorphus and made no mention of previous 

 reports that ridges are muscular (Tonutti, 1933; Wake, 1972). Wake 

 (1972) also referred to at least some phallodeal ornamentation as 

 transverse muscle ridges, whereas Wiedersheim (1879) stated that 

 the prominences are hardened parts of longitudinal folds of cloacal 

 mucosa. In at least one case it is clear that the prominences are not 

 muscular: large recurved calcified or cartilaginous spines are present 

 in Scolecomorphus uluguruensis Barbour and Loveridge, 1925 

 (Noble, 1931; Taylor, 1968;Nussbaum, 1985; Wake, 1998).Exbrayat 

 (1991) showed that tuberosities in the phallodeum of Typhlonectes 

 compressicauda are keratinous, and that their thickness varies with 

 the reproductive cycle. Exbrayat (1996) described smooth trans- 

 verse and striated longitudinal muscles in the wall of the cloaca of T. 

 compressicauda, with the latter forming the major longitudinal 

 ridges. Muscle therefore appears to be present in the longitudinal 

 phallodeal ridges of at least some species, but we find no clear 

 evidence that any of the tuberosities, crests etc found in the 

 phallodeum are muscular. 



close to the border between the phallodeum and urodeum. The sacs 

 extend anteriorly from the anterior end of the phallodeum so that, 

 within the coelom, they can be seen running parallel to the posterior 

 end of the urodeum (e.g. Wiedersheim, 1879: Fig. 88; this paper: 

 Figs. 2, 3). Thus, the blind sacs must be positioned at, or inside, the 

 distal end of the everted phallus (Tonutti, 1931: e.g. Fig. 22b of 

 Hypogeophis rostratus) rather than at its base. This can be clearly 

 seen by comparing the figures shown here of the uneverted and 

 everted phallodeum of Uraeotyphlus (Figs. 2 to 9), where the 

 entrance to the blind sacs are seen right at the distal termination of 

 the everted phallus (Figs. 4, 5). Preserved specimens may show 

 various degrees of phallodeal eversion, and it is clear that Wake's 

 figures are of partially everted organs, which may have misled her. 

 In our experience, the major dorsolateral sulci, their associated 

 ridges, and the colliculus are clearly visible at the distal end of a well 

 everted phallus, although the extent of phallodeal eversion during 

 copulation is unknown. 



Bons (1986) and Exbrayat (1991) also figured what we consider 

 to be partially everted phallodea of Typhlonectes compressicauda. 

 Typhlonectes have a distinctive 'cloacal disc' surrounding the vent 

 (Taylor, 1968) and Exbrayat's figure 3 appears to show the cloacal 

 disk at the distal tip of the protruding phallus, and seemingly 

 detached from the adjacent skin. However, the disc is continuous 

 with the surrounding skin and must remain at the base of the phallus 

 because it is everted rather than telescopically extended. 



Relationship between the uneverted cloaca and the phallus. 

 There is some confusion in the literature regarding the positional 

 relationship between structures as seen on the internal surface of the 

 uneverted phallodeum. and the same structures when observed on 

 the external surface of the phallus. Wake (1972: 359, Fig. 13, 15) 

 described and figured the blind sacs as being positioned at the 

 proximal base of the everted phallodeum in a thickened 'blind sac 

 sheath'. In the uneverted phallodeum, blind sacs, where present, are 

 pockets extending from the dorsal wall of the phallodeum, very 



SYSTEMATICS 



IS PHALLUS MORPHOLOGY SPECIES SPECIFIC? The family 



Uraeotyphlidae is monotypic, comprising five currently recognised 

 species of Uraeotyphlus endemic to peninsular India (Pillai & 

 Ravichandran, 1999). Uraeotyphlidae is the extant sister taxon of 

 the south and southeast Asian Ichthyophiidae (Wilkinson & 

 Nussbaum, 1996; Gower et «/., 2002; Wilkinson et al., 2002). As 



c.md 



Fig. 7 Uraeotyphlus cf. narayani (field tag MW 172). Anterior phallodeum of mature male, prepared as specimen shown in Fig. 6. Scale = 2 mm. 



