Loxocemus Cope, 1861

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

Loxocemus Cope, 1861

Material examined.

Loxocemus bicolor Cope, 1861 (MVZ Herps 143487 [Morphosource.org: Media 000076134, ark:/87602/m4/ M76134 ]; NHMUK 82.8.17.16, UF Herp 24747 [Morphosource.org: Media 000071842, ark:/87602/m4/ M71842 ]; UMMZ 128027; UMMZ 190749) .

Description (Figs 137-140).

Trunk vertebrae. Centrum shorter than wide; cotyle and condyle moderately depressed to orbicular; neural arch moderately vaulted; posterior median notch of the neural arch deep; neural spine as high as long; prezygapophyseal accessory processes very short; hypapophyses disappearing at the level of V 60; haemal keel flattened, moderately developed, approaching (but not exceeding) the width of the cotyle; prominent subcentral ridges and deep subcentral grooves in posterior trunk vertebrae; paracotylar foramina absent.

Szyndlar and Böhme (1996) highlighted that the most characteristic feature of the trunk vertebrae is the fusion of the subcentral ridges with parapophyses into uniform and flat laminae, rendering the centrum looking as a sharply delimited triangle in ventral view. Smith (2013) too highlighted the subcentral ridges, considering that the "extremely well-developed subcentral grooves and ridges of posterior vertebrae" represented an apomorphy.

Trunk / caudal transition. No subcentral structures occur on the last trunk, cloacal, and anteriormost caudal vertebrae or, at most, an indistinct flattened haemal keel may be present. Paired haemapophyses first appear on the C 3 in UMMZ 128027 or even the C 6 in UF Herp 24747. The posteriormost caudal vertebrae are fused.

Smith (2013) reported that the posteriormost trunk and cloacal vertebrae are provided with a hypapophysis, but we did not observe this pattern in our studied material.

Number of vertebrae (all for Loxocemus bicolor ). MVZ Herps 143487: 309 (262+4+43, including a final fusion); UMMZ 128027: 308 (256+4+48, including a final fusion); UF Herp 24747: 307 (258+4+45, including a final fusion).

Data from literature: Loxocemus bicolor : 267 trunk vertebrae plus unknown number of cloacal and caudal vertebrae ( Tsuihiji et al. 2012).