Anilius Oken, 1816

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

Anilius Oken, 1816

Material examined.

Anilius scytale (Linnaeus, 1758) MNHN-AC-1869.0772; MNHN-AC-1880.1892; MNHN-AC-1887.0901; MNHN-AC-1888.0186.

Description (Figs 19-25>).

Trunk vertebrae. Centrum elongate; cotyle and condyle strongly depressed; neural arch depressed; posterior median notch of the neural arch shallow (sometimes absent in posterior trunk vertebrae); neural spine with short anterior lamina that is very low, slightly shifted (but nor restricted to) the posterior portion of the neural arch; prezygapophyses elongate, reaching just shorter than the zygosphene and angled at around 20°-25° in anterior view; prezygapophyseal accessory processes short to moderate in length; hypapophyses plate-like (but elongate in the very anteriormost trunk vertebrae), restricted to the anterior trunk vertebrae, prominent until around V 30 and then diminishing in size until around V 40 to V 50; haemal keel in succeeding trunk vertebrae flattened; paracotylar foramina absent.

Smith (2013: 161) further highlighted the presence of "weak swellings in the position of subcotylar tubercles" that appear obvious at approximately V 120 and become small but distinct processes at around V 130.

Trunk / caudal transition. All last trunk, cloacal, and caudal vertebrae retain a relatively flattened haemal keel. Smith (2013: 161), who had access to one of our specimens (MNHN-AC-1869.0772) mentioned that haemapophyses are represented in this taxon "only by weak, bilateral bumps near the posterior margin of the first two or three postcloacals". Of course, this is simply a matter of terminology but we interpret this approach as “bumps” or tiny protrusions of a flattened haemal keel, instead of haemapophyses.

Number of vertebrae (all for Anilius scytale ): NHMUK 56.10.16: 253 (234+4+15, including three fused posteriormost caudal vertebrae); MNHN-AC-1869.0772: 239+ (223+4+12+).

Data from literature and unpublished data from personal communications (all for Anilius scytale ): 220 trunk vertebrae plus 4 cloacal vertebrae plus 14 caudal vertebrae (NHMUK 1855.5.28.23; Jason Head, unpublished data, personal communication to GLG); 217 trunk and cloacal vertebrae plus 16+ caudal vertebrae ( Alexander and Gans 1966); 217 trunk vertebrae plus 22 cloacal and caudal vertebrae ( Polly et al. 2001); 226 trunk vertebrae plus 37 cloacal and caudal vertebrae [the latter value seems erroneous] ( Nopcsa 1923); 231 trunk vertebrae plus 5 cloacal vertebrae (possibly erroneous) plus 32 caudal vertebrae ( Rochebrune 1881); 213 trunk vertebrae plus unknown number of cloacal and caudal vertebrae ( Gasc 1974); 209 trunk vertebrae plus unknown number of cloacal and caudal vertebrae ( Tsuihiji et al. 2012).

In general, it is interesting to note the very low number of caudal vertebrae in Anilius , where usually this number does not exceed 20. However, in older literature (if the respective counts of Rochebrune [1881] and Nopcsa [1923] were correct) there are reports of caudal vertebral counts higher than 30. Unfortunately, the specimens on which these counts are based are unknown.