Bolyeriidae Hoffstetter, 1946

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

Bolyeriidae Hoffstetter, 1946

General information.

Bolyeriidae includes only the two monotypic genera Bolyeria and Casarea from the Mascarene Islands, among which the former is now extinct since a few decades ago ( Wallach et al. 2014; Georgalis and Smith 2020). They were long considered as members of an “expanded” Boidae (e.g., Cope 1887; Stull 1935; Hoffstetter 1946, 1960; Anthony and Guibé 1952; Dowling 1959; Guibé 1970; Rage 1987). A sister group relationship with Tropidophiidae has also been proposed ( Underwood 1976; Wallach and Günther 1998), while other even directly included them within tropidophiids (e.g., Arnold 1980). According to recent phylogenies, the Asian Xenophidiidae are the closest relatives of bolyeriids (e.g., Lawson et al. 2004; Pyron and Burbrink 2012; Pyron et al. 2013; Figueroa et al. 2016), the two in turn forming the superfamily Bolyerioidea ( Georgalis and Smith 2020). Indeed, Bolyeriidae and Xenophidiidae possess a synapomorphy, a maxilla divided into separate anterior and posterior parts (e.g., Anthony and Guibé 1952; Maisano and Rieppel 2007), that is a unique feature among all tetrapods ( Georgalis and Smith 2020). Their exact affinities with other snakes are not established with certainty, with other phylogenies placing them close to Booidea ( Streicher and Wiens 2016; Zheng and Wiens 2016; Harrington and Reeder 2017; Burbrink et al. 2020) or Pythonoidea ( Lawson et al. 2004; species-tree analysis of Burbrink et al. 2020). Only subfossil remains from the Mascarenes exist ( Hoffstetter 1960; Arnold 1980), with no pre-Quaternary fossil record.

Vertebral morphology of Bolyeriidae is principally characterized by the presence of prominent hypapophyses throughout the trunk column (for more details see Description and figures of Bolyeria and Casarea below).

Previous figures of vertebrae of extant Bolyeriidae have been so far presented by Underwood (1976), Hecht and LaDuke (1988), and Palci et al. (2020). Among these, vertebrae from the cloacal and caudal series of bolyeriids have never been figured so far. Quantitative study on the intracolumnar variability of bolyeriid vertebrae was conducted by Hoffstetter (1960). Besides the published figures, several authors observed the presence of hypapophyses throughout the trunk portion of the column in bolyeriids (e.g., Romer 1956; Hoffstetter 1946, 1960, 1968; McDowell 1975; Rage 1984; Szyndlar and Rage 2003).