Scincidae

Scincidae View in CoL ( Fig. 24J–Q View Figure 24 )

In European scincids, the vomers are usually fused in a single, unpaired element, which reaches its maximum width at midlength ( Fig. 24J–M View Figure 24 ). Only Tr. aurata and Ophiomorus punctatissimus have separate vomers ( Fig. 24N–Q View Figure 24 ). The posterior end has roughly the same width as the anterior one. In dorsal view, the lateral margin of the posterior-half is straight, whereas the notch on that of the anterior one is moderately deep. Each lateral margin of the anterior end clearly has a concave articulation surface for the contact with the palatal process of the premaxilla (very little developed in Ab. kitaibelii ), whereas the contact surface with the incisive process is recognizable on the anterior tip of the bone. A posterodorsally directed process is present, as in gekkotans ( Villa et al., 2018a), but, because of the narrowing of the posterior end (which develops a pointed or rounded medial tip, similar to the medial posterior process of lacertids), this process is slightly shifted medially, compared to the one of gekkotans, and tends to partially cover the posterior end in dorsal view. The process is moderately wide, laminar and posteriorly truncated; its ridge-like ventral margin marks dorsally the surface that houses the vomerine process of the palatine. It is very little developed, almost absent, in Ab. kitaibelii ( Fig. 24J View Figure 24 ). A small and narrow notch separates the posterior tips of the two fused vomers. Three well-developed ridges are present on the dorsal surface of the fused complex of bones: a longitudinal one running along its midline and two transverse ones located at midlength. The latter start from each lateral margin, but reach the longitudinal ridge only in Tr. aurata ( Fig. 24P View Figure 24 ), in which the channel separating them appears as an anteroposteriorly directed foramen. The transverse ridges are well developed in Ab. kitaibelii , Chalcides chalcides , Chalcides striatus and Tr. aurata ( Fig. 24J, P View Figure 24 ), low in Chalcides ocellatus ( Fig. 24L View Figure 24 ) and almost indistinct in Ophiomorus punctatissimus ( Fig. 24N View Figure 24 ). Dorsally, the two portions of the longitudinal ridge (one for each vomer) may remain unfused. With the exception of Ab. kitaibelii and Ophiomorus punctatissimus ( Fig. 24J, N View Figure 24 ), two other low (very low in Chalcides striatus ) and transverse ridges are visible roughly at the middle of the notch of the vomeronasal foramen, located on both sides of the longitudinal ridge and touching it medially ( Fig. 24L, P View Figure 24 ). The ventral surface of the vomer is smooth, except for a wide groove located along the midline and two symmetrical foramina located near the anterior end. The ventral groove can house some other foramina too. Ablepharus kitaibelii lacks the two foramina and the posterior end of its groove is closed ventrally by osseous expansions of the margins ( Fig. 24K View Figure 24 ). Ophiomorus punctatissimus lacks any sign of a ventral groove ( Fig. 24O View Figure 24 ), but some foramina are present near the anterior end.