Cylindrophiidae Fitzinger, 1843, 1901

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

Cylindrophiidae Fitzinger, 1843

General information.

Cylindrophiids consist a monotypic family of uropeltoids, with a single genus, Cylindrophis and more than a dozen species, distributed only in Sri Lanka, southeastern Asia, and Indonesia ( Wallach et al. 2014; Boundy 2021).

The vertebral morphology of cylindrophiids is primarily characterized by an elongate centrum, depressed cotyle and condyle, depressed neural arch, absent or very shallow median notch of the neural arch, absent haemal keels in mid- and posterior trunk vertebrae, neural spine vestigial and restricted to the posterior portion of the neural arch (disappearing entirely in the posterior vertebrae), absence of any subcentral structures in the cloacal and caudal portion of the column (with the exception of a moderately developed ridge-like keel in the last cloacal and two succeeding caudal vertebrae in Cylindrophis ruffus ), and a very low number of caudal vertebrae (for more details, see Description and figures of Cylindrophis below).

Previous figures of vertebrae of extant Cylindrophiidae have been so far presented by Rochebrune (1881), Williams (1954, 1959), Gasc (1974), Hoffstetter and Rage (1977), Rieppel (1979), Polly and Head (2004), Ikeda (2007), Xing et al. (2018), Fachini et al. (2020), Palci et al. (2020), Head (2021), and Alfonso-Rojas et al. (2023). Among these, vertebrae from the cloacal and caudal series were presented by Gasc (1974), Palci et al. (2020), and Alfonso-Rojas et al. (2023). Quantitative studies on the intracolumnar variability of cylindrophiid vertebrae were conducted by Gasc (1974), Polly and Head (2004), and Head (2021).