Typhlopidae Gray, 1825, 2009

Szyndlar, Zbigniew & Georgalis, Georgios L., 2023, An illustrated atlas of the vertebral morphology of extant non-caenophidian snakes, with special emphasis on the cloacal and caudal portions of the column, Vertebrate Zoology 73, pp. 717-886 : 717

Typhlopidae Gray, 1825

General information.

Typhlopidae is the most speciose family of scolecophidians and is currently distributed over large parts of Africa, Asia, the Americas, Oceania, and southeastern Europe ( Hedges et al. 2014; Pyron and Wallach 2014). For several decades, all typhlopids had been referred to a single genus, Typhlops Schneider, 1801, or to two genera, Typhlops and Rhinotyphlops Fitzinger, 1843 (e.g., Roux-Estève 1974a, 1974b), but recent advances in molecular phylogenetics and more thorough knowledge of external morphologies have suggested instead an assignement into several other genera ( Broadley and Wallach 2007, 2009; Hedges et al. 2014; Pyron and Wallach 2014). Divergence date estimates suggest that typhlopids split from other scolecophidians already during the Late Cretaceous ( Zheng and Wiens 2016; Sidharthan and Karanth 2021; Tiatragul et al. 2023). Typhlopidae were also called during the 19th century under the name Epanodontia (or Epanodonta or Épanodontiens) ( Duméril et al. 1854, 1870-1909; Carus 1868; Cope 1887, 1894, 1895, 1898), a term apparently evoking to the fact that they possess teeth ( “οδόντες”) solely on their upper ( “επάνω”) jaws, i.e., the name counterparting Catodontia (i.e., Leptotyphlopidae ).

Previous figures of vertebrae of extant Typhlopidae have been so far presented by Rochebrune (1881), Mookerjee and Das (1933), Mahendra (1935, 1936), Hoffstetter (1939b), Evans (1955), List (1966), Hoffstetter and Gasc (1969), Lee and Scanlon (2002), Nakamura et al. (2013), Palci et al. (2013a), Xing et al. (2018), Fachini et al. (2020), Hawlitschek et al. (2021), Herrel et al. (2021), Lira and Martins (2021), and Peralta and Ferrero (2023), including also from individuals of earlier ontogenetic stages ( Xing et al. 2018). Among these, vertebrae from the cloacal and/or caudal series were presented by Evans (1955) and List (1966). Figures of the microanatomy and histology / transverse sections of typhlopid vertebrae were presented by Mookerjee and Das (1933) and Sood (1948). Quantitative studies on the intracolumnar variability of typhlopid vertebrae was conducted by Gasc (1974) and Head (2021).

Material examined.

Acutotyphlops kunuaensis Wallach , 1995 (FMNH 44800 [Morphosource.org: Media 000052992, ark:/87602/m4/ M52992 ]); Afrotyphlops punctatus ( Leach in Bowdich , 1819) (NHMUK 1911.6.9.2); Afrotyphlops steinhausi ( Werner , 1909) (MNHN-ZA-AC-1964.0042); Amerotyphlops brongersmianus ( Vanzolini , 1976) (FMNH 195928 [Morphosource.org: Media 000065157, ark:/87602/m4/ M65157 ]); Amerotyphlops microstomus ( Cope , 1866) (UCM Herp 40750 [Morphosource.org: Media 000438912, ark:/87602/m4/438912]); Anilios erycinus ( Werner , 1901) (UF Herp 113561 [Morphosource.org: Media 000448363, ark:/87602/m4/448363); Anilios torresianus ( Boulenger , 1889) (UMMZ 83512 [Morphosource.org: Media 000386190, ark:/87602/m4/386190]); Antillotyphlops hypomethes (Hedges & Thomas, 1991) (MCZ Herp R-38322 [Morphosource.org: Media 000048876, ark:/87602/m4/ M48876 ]); Argyrophis diardii ( Schlegel , 1839 in Schlegel 1837 -1844) (MNHN-AC-1908.0115); Argyrophis muelleri ( Schlegel , 1839 in Schlegel 1837 -1844) (FMNH H 259200 [Morphosource.org: Media 000069969, ark:/87602/m4/ M69969 ]); Cubatyphlops biminiensis ( Richmond , 1955) (MCZ Herp R-69444 [Morphosource.org: Media 000393020, ark:/87602/m4/393020]); Grypotyphlops acutus ( Duméril & Bibron, 1844) (MCZ Herp R-3849 [Morphosource.org: Media 000350220, ark:/87602/m4/350220]); Indotyphlops braminus (MNHN-AC-1911.0030; UF Herp 29433 [Morphosource.org: Media 000493259, ark:/87602/m4/493259]); Madatyphlops arenarius ( Grandidier , 1872) (UMMZ 241854 [Morphosource.org: Media 000070129, ark:/87602/m4/ M70129 ]); Rhinotyphlops lalandei ( Schlegel , 1839 in Schlegel 1837 -1844) (UMMZ 61525 [Morphosource.org: Media 000083066, ark:/87602/m4/ M83066 ]); Typhlops gonavensis Richmond, 1964 (YPM VZ Her 003003 [holotype] [Morphosource.org: Media 000495769, ark:/87602/m4/495769]); Typhlops lumbricalis (Linnaeus, 1758) (YPM VZ Her 003000 [Morphosource.org: Media 000068126, ark:/87602/m4/ M68126 ]); Xerotyphlops syriacus (Jan, 1864) (ISEZ R/407); Xerotyphlops vermicularis (Merrem, 1820) (MGPT-MDHC 197; MGPT-MDHC 293; NHMW 33838) .

Description (Figs 5 - 13 ).

Trunk vertebrae. The morphology of the trunk vertebrae is very similar to leptotyphlopids. See the respective part in Leptotyphlopidae above.

Worth noting here is that, contrary to most leptotyphlopids, a single asymmetrical subcentral foramen is present in several (but not all) trunk vertebrae of typhlopids (see above "Vertebral distinction among scolecophidian families").

Trunk / caudal transition. The morphology of these vertebrae is overall similar to leptotyphlopids. See the respective part in Leptotyphlopidae above.

Number of vertebrae. Acutotyphlops kunuaensis (FMNH 44800): 280 (267+5+8, including a final fusion); Afrotyphlops punctatus (NHMUK 1911.6.9.2): 188+ (183+5+0+); Amerotyphlops brongersmianus (FMNH 195928): 149 (138+4+7, including a final fusion); Amerotyphlops microstomus (UCM Herp 40750): ~310 vertebrae in total; Anilios erycinus (UF Herp 113561): 183 (173+3+7, including a final fusion); Anilios torresianus (UMMZ 83512): 221 (208+4+9, including a final fusion); Antillotyphlops hypomethes (MCZ Herp R-38322): 218 (205+3+10, including a final fusion); Argyrophis diardii (MNHN-AC-1911.0030): 192+ (190+2+0+); Argyrophis muelleri (FMNH H 259200): 176 (167+4+5, including a final fusion); Cubatyphlops biminiensis (MCZ Herp R-69444): 273 (260+4+9, including a final fusion); Grypotyphlops acutus (MCZ Herp R-3849): 267 (255+5+7, including a final fusion); Indotyphlops braminus (UF Herp 29433): 270 (244+3+23, including a final fusion); Madatyphlops arenarius (UMMZ 241854): 180 trunk vertebrae (cloacal and caudal vertebrae are missing, perhaps also some posteriormost trunk vertebrae); Rhinotyphlops lalandei (UMMZ 61525): 199 (187+3+9, including a final fusion); Typhlops gonavensis (YPM VZ Her 003003 [holotype]): 247 (236+4+7, including a final fusion); Typhlops lumbricalis (YPM VZ Her 003000): 179 (167+4+8, including a final fusion); Xerotyphlops vermicularis (MGPT-MDHC 197): 211+ vertebrae in total.

Data from literature and unpublished data from personal communications: Acutotyphlops infralabialis (Waite, 1918): 289 trunk and cloacal vertebrae plus 13 caudal vertebrae ( Alexander and Gans 1966); Acutotyphlops solomonis (Parker, 1939): 219-222 trunk and cloacal vertebrae plus 13-16 caudal vertebrae ( Alexander and Gans 1966); Afrotyphlops angeli ( Guibé, 1952): 332 vertebrae in total ( Roux-Estève 1974a); Afrotyphlops angolensis (Bocage, 1866): 209-236 vertebrae in total in males and 213-236 vertebrae in total in females ( Roux-Estève 1975); Afrotyphlops angolensis : 206-246 vertebrae in total ( Broadley and Wallach 2007); Afrotyphlops anomalus (Bocage, 1873): 184-203 vertebrae in total in males and 198-206 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops bibronii (Smith, 1846 in Smith 1838-1849): 182-212 vertebrae in total in males and 197-223 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops blanfordii (Boulenger, 1889): 233 trunk vertebrae plus 4 cloacal vertebrae plus 11 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Afrotyphlops brevis (Scortecci, 1929): 190-250 vertebrae in total ( Roux-Estève 1974a, 1974b); Afrotyphlops calabresii (Gans & Laurent, 1965): 130-153 trunk and cloacal vertebrae plus unknown number of caudal vertebrae ( Gans and Laurent 1965; Alexander and Gans 1966); Afrotyphlops congestus ( Duméril & Bibron, 1844): 180-182 trunk and cloacal vertebrae plus 7-12 caudal vertebrae ( Alexander and Gans 1966); Afrotyphlops congestus : 185-201 vertebrae in total in males and 191-206 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops cuneirostris : 115-126 trunk and cloacal vertebrae plus unknown number of caudal vertebrae ( Gans and Laurent 1965; Alexander and Gans 1966); Afrotyphlops cuneirostris : 115-153 vertebrae in total ( Roux-Estève 1974a, 1974b); Afrotyphlops decorosus (Buchholz & Peters in Peters, 1875): 307 vertebrae in total in males and 313-320 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops elegans (Peters, 1868): 210-218 vertebrae in total in males and 214-220 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops fornasinii (Bianconi, 1849): 144-159 vertebrae in total in males and 155-167 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops gierrai (Mocquard, 1897): 219-231 vertebrae in total in males and 225-242 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops liberiensis (Hallowell, 1848): 196-213 vertebrae in total in males and 201-218 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops lineolatus (Jan, 1864): 184-209 vertebrae in total in males and 187-214 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops manni (Loveridge, 1941): 301-332 vertebrae in total ( Roux-Estève 1974a, 1974b); Afrotyphlops mucruso (Peters, 1854): 197 trunk vertebrae plus 5 cloacal vertebrae plus 8 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Afrotyphlops mucruso : 166-202 vertebrae in total in males and 182-224 vertebrae in total in females ( Rhinotyphlops schlegelii dinga of Roux-Estève 1974a); Afrotyphlops nigrocandidus (Broadley & Wallach, 2000): 242 vertebrae in total ( Broadley and Wallach 2007); Afrotyphlops obtusus (Peters, 1865): 251-261 vertebrae in total in males and 252-271 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops punctatus : 191-219 vertebrae in total in males and 201-224 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops punctatus : 181 trunk vertebrae plus 11 cloacal and caudal vertebrae ( Nopcsa 1923); Afrotyphlops rondoensis (Loveridge, 1942): 197-216 vertebrae in total ( Roux-Estève 1974a, 1974b); Afrotyphlops schlegelii (Bianconi, 1849): 184 trunk vertebrae plus 5 cloacal vertebrae plus 9 caudal vertebrae (posteriormost 4 caudal vertebrae are fused) ( List 1966); Afrotyphlops schlegelii : 175-187 vertebrae in total in males and 194-206 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops schmidti (Laurent, 1956): 188-212 vertebrae in total ( Broadley and Wallach 2007); Afrotyphlops steinhausi : 235-245 vertebrae in total in males and 241-255 vertebrae in total in females ( Roux-Estève 1974a); Afrotyphlops tanganicanus (Laurent, 1964): 227-247 vertebrae in total ( Roux-Estève 1974a, 1974b); Afrotyphlops usambaricus (Laurent, 1964): 196-211 vertebrae in total ( Broadley and Wallach 2007); Amerotyphlops reticulatus (Linnaeus, 1758): 140 trunk vertebrae plus 3 cloacal vertebrae plus 9 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Anilios ammodytes (Montague, 1914): 193-231 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios australis Gray, 1845: 145-164 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios bicolor (Schmidt in Peters, 1858): 145-173 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios bituberculatus (Peters, 1863): 219-300 trunk and cloacal vertebrae plus 13-15 caudal vertebrae ( Alexander and Gans 1966); Anilios diversus (Waite, 1894): 186-230 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios endoterus (Waite, 1918): 203-245 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios fossor Shea, 2015: 250 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios ganei (Aplin, 1998): 195-223 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios guentheri (Peters, 1865): 249-293 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios hamatus (Storr, 1981): 170-192 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios kimberleyensis (Storr, 1981): 188-250 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios leptosomus (Robb, 1972): 288-334 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios ligatus (Peters, 1879): 140-166 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios nigrescens Gray, 1845: 183-218 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios pilbarensis (Aplin & Donnellan, 1993): 185-210 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios pinguis (Waite, 1897): 144-151 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Anilios proximus (Waite, 1893): 160-173 trunk and cloacal vertebrae plus 7-12 caudal vertebrae ( Alexander and Gans 1966); Anilios torresianus : 196 trunk and cloacal vertebrae plus 10-16 caudal vertebrae ( Alexander and Gans 1966); Anilios waitii (Boulenger, 1895): 214-310 trunk vertebrae plus unknown number of cloacal and caudal vertebrae (Sarin Tiatragul, unpublished data, personal communication to GLG); Cyclotyphlops deharvengi Bosch & Ineich, 1994: 154 trunk vertebrae plus ~12 cloacal and caudal vertebrae (posteriormost caudal vertebrae are fused) (counted from the radiograph of the holotype in Bosch and Ineich 1994: fig. 7); Indotyphlops braminus : 170-180 trunk vertebrae plus 3 cloacal vertebrae plus 10-11 caudal vertebrae (posteriormost 2-3 caudal vertebrae are fused) ( List 1966); Indotyphlops braminus : 154 trunk vertebrae plus 3 cloacal vertebrae plus 7 caudal vertebrae ( Rochebrune 1881); Indotyphlops braminus : 179-196 vertebrae in total ( Roux-Estève 1974b); Indotyphlops braminus : 178-206 vertebrae in total ( Roux-Estève 1974a); Letheobia caeca ( Duméril, 1856): 322-347 vertebrae in total in males and 336-371 vertebrae in total in females ( Roux-Estève 1974a); Letheobia caeca : 349 vertebrae in total ( Trape and Roux-Estève 1990); Letheobia caeca : 310-336 vertebrae in total ( Roux-Estève 1975); Letheobia coecata (Jan, 1863): 200-228 vertebrae in total ( Roux-Estève 1969, 1974a, 1974b); Letheobia crossii (Boulenger, 1893): 307-317 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia debilis (Joger, 1990): 443 vertebrae in total ( Broadley and Wallach 2007); Letheobia decorosa (Buchholz & Peters in Peters, 1875): 285-320 vertebrae in total ( Broadley and Wallach 2007); Letheobia feae (Boulenger, 1906): 311 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia gracilis (Sternfeld, 1910): 377-426 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia graueri (Sternfeld, 1913): 316-382 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia kibarae (Witte, 1953): 345-370 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia leucosticta (Boulenger, 1898): 236 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia lumbriciformis (Peters, 1874): 362-364 vertebrae in total in males and 374-382 vertebrae in total in females ( Roux-Estève 1974a); Letheobia newtoni (Bocage, 1890): 290-321 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia obtusa (Peters, 1865): 251-271 vertebrae in total ( Broadley and Wallach 2007); Letheobia pallida Cope, 1869: 235-303 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia praeocularis (Stejneger, 1894): 333-358 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia rufescens (Chabanaud, 1917): 442-448 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia somalica (Boulenger, 1895): 301-391 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia stejnegeri (Loveridge, 1931): 307-367 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia sudanensis (Schmidt, 1923): 366 vertebrae in total in males and 379-408 vertebrae in total in females ( Roux-Estève 1974a); Letheobia swahilica Broadley & Wallach, 2007: 235-260 vertebrae in total ( Broadley and Wallach 2007); Letheobia toritensis Broadley & Wallach, 2007: 280-303 vertebrae in total ( Broadley and Wallach 2007); Letheobia uluguruensis (Barbour & Loveridge, 1928): 263-269 vertebrae in total ( Gower et al. 2004); Letheobia uluguruensis : 263 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia wittei ( Roux-Estève, 1974): 368-374 vertebrae in total ( Roux-Estève 1974a, 1974b); Letheobia zenkeri (Sternfeld, 1908): 193-199 vertebrae in total ( Roux-Estève 1974a, 1974b); Madatyphlops andasibensis (Wallach & Glaw, 2009): 180-186 trunk vertebrae plus 5 cloacal vertebrae plus 7-9 caudal vertebrae (posteriormost caudal vertebrae are fused) ( Wallach and Glaw 2009); Madatyphlops boettgeri (Boulenger, 1893): 196 trunk vertebrae plus 4 cloacal vertebrae plus 7 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Madatyphlops domerguei ( Roux-Estève, 1980): 170 vertebrae in total ( Roux-Estève 1980); Madatyphlops platyrhynchus (Sternfeld, 1910): 218-227 vertebrae in total ( Roux-Estève 1974a, 1974b); Malayotyphlops luzonensis (Taylor, 1919): 208 trunk and cloacal vertebrae plus 10 caudal vertebrae ( Alexander and Gans 1966); Ramphotyphlops depressus Peters, 1880:?175-181 trunk and cloacal vertebrae plus?11-15 caudal vertebrae ( Alexander and Gans 1966); Ramphotyphlops flaviventer (Peters, 1864): 203 trunk vertebrae plus 4 cloacal vertebrae plus 13 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Ramphotyphlops lineatus (Schlegel, 1839 in Schlegel 1837 -1844): 251 trunk vertebrae plus 3 cloacal vertebrae plus 8 caudal vertebrae (posteriormost 3 caudal vertebrae are fused) ( List 1966); Rhinotyphlops ataeniatus (Boulenger, 1912): 297-307 trunk and cloacal vertebrae plus unknown number of caudal vertebrae ( Gans and Laurent 1965; Alexander and Gans 1966); Rhinotyphlops boylei (FitzSimons, 1932): 211-212 vertebrae in total ( Roux-Estève 1974a, 1974b); Rhinotyphlops lalandei : 195-211 vertebrae in total in males and 195-222 vertebrae in total in females ( Roux-Estève 1974a); Rhinotyphlops leucocephalus (Parker, 1930): 193 vertebrae in total ( Roux-Estève 1974a); Rhinotyphlops schinzi (Boettger, 1887): 219-237 vertebrae in total in males and 223-244 vertebrae in total in females ( Roux-Estève 1974a); Rhinotyphlops scorteccii (Gans & Laurent, 1965):?226-255 trunk and cloacal vertebrae plus unknown number of caudal vertebrae ( Gans and Laurent 1965; Alexander and Gans 1966); Rhinotyphlops scorteccii : 235-237 vertebrae in total in males and 241-255 vertebrae in total in females ( Roux-Estève 1974a); Rhinotyphlops unitaeniatus (Peters, 1878): 315-334 trunk and cloacal vertebrae plus unknown number of caudal vertebrae ( Gans and Laurent 1965; Alexander and Gans 1966); Rhinotyphlops unitaeniatus : 299-332 vertebrae in total ( Roux-Estève 1974a, 1974b); Sundatyphlops polygrammicus (Schlegel, 1839 in Schlegel 1837 -1844): 190-216 trunk vertebrae plus 3-5 cloacal vertebrae plus 14-18 caudal vertebrae (posteriormost 3-4 caudal vertebrae are fused) ( List 1966); Typhlops jamaicensis (Shaw, 1802): 200 trunk vertebrae plus 15 cloacal and caudal vertebrae ( Polly et al. 2001); Typhlops jamaicensis : 200-205 vertebrae in total, of which at least 10 are caudal ones ( Evans 1955); Typhlops lumbricalis : 166 trunk vertebrae plus 3 cloacal vertebrae plus 10 caudal vertebrae (posteriormost 2 caudal vertebrae are fused) ( List 1966); Typhlops lumbricalis : 176 trunk vertebrae plus 10 cloacal and caudal vertebrae ( Janensch 1906); Typhlops lumbricalis : 175 trunk vertebrae plus 3 cloacal vertebrae plus 10 caudal vertebrae ( Rochebrune 1881); Typhlops platycephalus Duméril & Bibron, 1844: 217 trunk vertebrae plus 5 cloacal vertebrae plus 11 caudal vertebrae (posteriormost 4 caudal vertebrae are fused) ( List 1966); Typhlops pusillus Barbour, 1914: 155 trunk vertebrae plus 3 cloacal vertebrae plus 12 caudal vertebrae (posteriormost 4 caudal vertebrae are fused) ( List 1966); Typhlops richardii Duméril & Bibron, 1844: 201 trunk vertebrae plus 3 cloacal vertebrae plus 13 caudal vertebrae (posteriormost 4 caudal vertebrae are fused) ( List 1966); Typhlops rostellatus Stejneger, 1904: 179 trunk vertebrae plus 4 cloacal vertebrae plus 10 caudal vertebrae (posteriormost 2 caudal vertebrae are fused) ( List 1966); Xerotyphlops socotranus (Boulenger, 1889): 226 vertebrae in total ( Roux-Estève 1974a, 1974b); Xerotyphlops vermicularis : 189 trunk vertebrae plus 4 cloacal vertebrae plus 12 caudal vertebrae (posteriormost 4 caudal vertebrae are fused) ( List 1966).

In general, there is plenty of information on the vertebral counts for many typhlopid genera and species. The largest amount of these data was provided in the monumental work of Roux-Estève (1974a), which, however, revealed information only about the total vertebral counts and not for particular regions of the column. One of the most striking features observed in typhlopids (like in many other scolecophidians) is the great intraspecific variation in the count of vertebrae of several taxa, particularly the trunk vertebrae. Such huge intraspecific vertebral number variation is observed in many genera and is more prominent in some species of Letheobia , where sometimes this difference exceeds the 100 vertebrae in the same species (see Roux-Estève 1974a). The average vertebral number of males is lower than that of females ( Roux-Estève 1974a). In addition, that number is also correlated to elevation of the animal’s habitat, with the number decreasing towards the sea-level ( Roux-Estève 1974a). Wallach (2009) reported that the number of vertebrae for the widespread (and in many areas invasive; see Wallach 2009; Ineich et al. 2017) species Indotyphlops braminus was geographically variable - we also observed a large variation in our studied sample and literature data for the same species. Notably, some species of Letheobia possess among the highest numbers of total vertebrae among all snakes, surpassing the 400, reaching even 448 in one species; in addition, in many species of that genus the total number of vertebrae is above 300, while the minimum recorded for the genus is 193 in one species. The genus Rhinotyphlops , also achieves high vertebral counts, reaching up to 334 in one species. The same applies to the genus Anilios Gray, 1845, two species of which have more than 300 trunk vertebrae although other species of this genus possess as few as less than 150 trunk vertebrae. More or less, the same is the case with the genus Amerotyphlops Hedges et al., 2014, where one species has more than 300 vertebrae in total, while in other two studied congeners, this numbers is only around 150. High numbers (more than 260) of total counts of vertebrae are also observed in the genera Cubatyphlops Hedges et al., 2014, and Grypotyphlops Peters, 1881. In contrast, the lowest numbers of total vertebral counts in typhlopids (and all snakes in general) are observed in Afrotyphlops Broadley & Wallach, 2009, where in one species this reaches the minimum of 115, though in other congeners this number can still go as high as 332. The number of caudal vertebrae in typhlopids is generally lower than that of leptotyphlopids, with most species (for which such rare available data do exist) possessing only around ~10 caudal vertebrae (with 5 being the lowest recorded number and 22 the highest one). Unfortunately, caudal vertebral counts have not been ever recorded for Letheobia , the typhlopid with (by far) the highest total number of vertebrae.

Figures

Figure 5. Typhlopidae: Afrotyphlops punctatus (NHMUK 1911.6.9.2), anterior trunk vertebrae.

Figure 13. Typhlopidae: Xerotyphlops syriacus (ISEZ R / 407), trunk vertebra.