Speleomantes

Macaluso, Loredana, Wencker, Lukardis C M, Castrovilli, Maria, Carnevale, Giorgio & Delfino, Massimo, 2023, A comparative atlas of selected skeletal elements of European urodeles (Amphibia: Urodela) for palaeontological investigations, Zoological Journal of the Linnean Society 197 (3), pp. 569-619 : 587-588

SPELEOMANTES DUBOIS, 1984

Species: Speleomantes ambrosii * (Lanza, 1955) , Speleomantes flavus , Speleomantes genei (Temminck & Schlegel, 1838) , Speleomantes imperialis , Speleomantes italicus * (Dunn, 1923) , Speleomantes sarrabusensis , Speleomates strinatii * (Aellen, 1958) and Speleomantes supramontis .

Otic–occipitum complex ( Fig. 4A )

The otic–occipitum complex is generally smooth, with rounded and well-defined prominentiae semicircularis anterioris, posterioris and lateralis on the dorsal surface. Between them, a deep middle depression shows no minor foramina in its floor. The circular fenestra ovalis is covered in both dorsal and posterior views by the prominentia lateralis and posterioris, respectively. The latter is prominent in lateral view, between the cotyle and the fenestra ovalis, and a sulcus separates it from the opening of the fenestra ovalis. The dorsal edge of the fenestra is located at the mid-height of the complex, and its anterior edge is at the mid-length or slightly anterior. The parietal and parotic crests are absent or limited to a small and sharp, anteriorly pointing tip on the anterior part of the prominentia lateralis; the parotic process is also absent. The anterior edge of the tectum synoticum in medial view is located at the mid-length of the complex. The tectum is extended medially beyond the hypochordal commissure in posterior view, and beyond the prefacial commissure in dorsal view, but a concavity is visible between the two processes. The elliptical postoticum foramen is dorsal to the cotyle, surrounded posteriorly by the prominentia posterioris and the lamina of the tectum synoticum. The otic process and the processus basalis are not anteriorly projecting, but limited to flat, bean-shaped articular surfaces that are oriented anterolaterally. The sulcus petrosus is deep between them. The foramen faciale is visible on the lateral side, dorsolateral to the processus basalis, and it is the only foramen visible on the ventral surface of the complex. In anterior view, the basicapsular commissure is as medially developed as, or more medially developed than, the prefacial commissure. In anterior view, two foramina are present on the ventral half of the basicapsular commissure. The foramen prooticum is not completely surrounded by bone, and two additional foramina are visible in medial view in its concavity. The auditory cavity is deep, and the individual foramina for the different branches of the acoustic nerve are not visible. In ventral view, the sulcus is not clearly visible, and the hypochordal and basicapsular commissures are equally developed and irregular, with an indented margin between them, meaning that the fenestra basicranialis is not evident.

Remarks: In MDHC 61 ( Speleomantes italicus ), a low parietal crest is visible in the anterior part of the prominentia semicircularis anterioris, parallel to a low parotic crest on the anterior part of prominentia lateralis. The crests are not present in the other specimen of Speleomantes italicus (MNCN 1839) .

Atlas ( Fig. 6C )

The neural canal is circular or triangular in anterior view and is at least twice as high as each occipital joint. In posterior view, the neural canal is three times as wide as the cotyle; the latter is circular or elliptical, with the major axis being horizontal. The occipital joints are elliptical, with the minor axis being horizontal (or subhorizontal). The articular facets of the odontoid process are separated by a wide groove on the ventral surface. In ventral view, the base of the odontoid process is wider than each occipital joint. In all specimens, the neural crest is absent, and the walls of the neural arch are not medially fused; instead, there are two articular surfaces, visible in dorsal view, connected by cartilage. Similar to what we observed in Salamandrella , it is likely that this character represents an immature ontogenetic trait and that in the completely ossified atlantes a bulge is present instead of the neural crest ( Wake, 1966). The secondary crests and the neural spine are absent. The lateral surface of the atlas bears only the foramen of the first spinal nerve. The incisura vertebralis cranialis is generally absent or small. In lateral view, the dorsal edge of the neural arch is sub-horizontal. The neural arch between the wide incisura caudalis and the cotyle is convex or sub-vertical. The maximum concavity of the incisura vertebralis caudalis is dorsal to the horizontal plane containing the maximum concavity of the incisura cranialis. The lateral crests are absent, and the inferior crests are low or absent. In posterior view, the neural arch is dorsally convex (inverted U-shaped). In lateral view, the postzygapophyses extend posteriorly beyond the cotyle for more than half of their length. In dorsal view, the neural arch displays a V-shaped concavity anteriorly and a U-shaped incisura dorsalis posteriorly. The cotyle is generally not visible in dorsal view or visible only slightly, in the middle of the incisura dorsalis. The ventral surface is usually smooth or bears a single concavity at its mid-length.

Precaudal vertebrae ( Fig. 9C, D )

The precaudal vertebrae are amphicoelous. The neural canal is circular in anterior view, being slightly higher or lower than the cotyle. The cotyles are circular or slightly elliptical, with the major axis being horizontal. In lateral view, the anterior edge of the neural arch between the cotyle and prezygapophyses is concave or vertical. In the first two or three precaudal vertebrae ( Fig. 9C ), diapophyses and parapophyses are not fused, and they are not connected by any lamina. For the vertebrae of the rest of the trunk ( Fig. 9D ), diapophyses and parapophyses are usually fused and not recognizable (unicipital transverse processes). The cylindrical transverse processes generally lie in a horizontal plane or form a slight dorsal concavity. They are slightly posteriorly oriented (posteriorly concave), but they do not cover the posterior edge of the neural arch in lateral view. In lateral view, most of the height of the vertebrae is formed by the centrum and the neural canal (only onefifth of the height of the vertebra is formed by the neural arch dorsal to the postzygapophyses). In lateral view, the neural arch dorsal to the prezygapophyses is not visible. The neural crest is low, starting from the anterior edge of the neural arch, and is higher in the mid-length of the vertebra. The neural spine is present in the form of a low and thick bulge that is posteriorly convex and not extended particularly beyond the postzygapophyses. The posterodorsal end of the neural arch is anterior to the postzygapophyses in lateral view. The anterior and posterior zygapophyseal and ventral crests are absent. The lateral surface of the vertebrae is smooth, except for a small foramen, sometimes hidden by the transverse processes. In the first precaudal vertebrae, there are one or two additional foramina. In lateral view, the dorsal edge of the neural arch is anteriorly sub-horizontal. The incisura vertebralis caudalis is not deep and is present only as a small posterior concavity (wider in the first precaudal vertebrae). The posterior edge of the neural arch between the centrum and postzygapophyses is slightly concave or sub-vertical. In posterior view, the neural arch is dorsally convex (U- or V-shaped). In lateral view, the postzygapophyses extend posteriorly beyond the cotyle for more than half of their length. In dorsal view, the neural arch displays an anteriorly U-shaped concavity and a variably visible V-shaped incisura dorsalis posteriorly. The edge of the anterior cotyle is visible in dorsal view, whereas the posterior cotyle is not visible. In lateral view, the ventral profile of the centrum is strongly concave. The ventral surface is generally smooth.

Remarks: The anterior vertebrae are recognizable because the neural canal is particularly wide (two or three times the condyle diameter) and because they bear one or two additional foramina, located anterior or posterior to the transverse processes, visible in lateral view. These vertebrae are also shorter and higher than the subsequent ones and bear a higher neural crest. In the sacral vertebra, the diapophyses and the parapophyses are fused, although sometimes still recognizable.

Caudal vertebrae ( Fig. 12C )

The caudal vertebrae are not particularly high (height/ length ratio <1.25). The neural and haemal canals are pentagonal or circular. The neural canal is wider and lower than the haemal canal. The transverse processes are transformed in horizontal laminae; in dorsal view, they are wide and fan-like. The neural crest is absent or low. Zygapophyseal and ventral crests are absent. The lateral surface is smooth, with a single foramen visible at the base of the haemal arch. In lateral view, the anterior edge of the haemal arch is concave or posteriorly inclined, whereas the posteroventral edge of the haemal arch forms a sharp tip in lateral view. In ventral view, the posterior end of the haemal arch is not forked. The haemal crest is high and generally more anteriorly projected than the haemal arch, forming a sharp or rounded tip.

Figures

Figure 4. Otic–occipitum complexes of European urodeles (Plethodontidae, Salamandrininae and Salmandrinae). A, left complex of Speleomantes strinatii (MDHC 225). B, left complex of Salamandrina perspicillata (MDHC 407). C, right complex of Chioglossa lusitanica (MNCN 16099; ventral view of the left complex because the right one is anomalous; see main text). D, right complex of Mertensiella caucasica (MNCN 23821). E, left complex of Salamandra salamandra (MDHC 227). From left to right: dorsal, ventral, anterior, posterior, medial and lateral views. Scale bars: 1 mm.

Figure 6. Atlantes of European urodeles. A, Salamandrella keyserlingii (BSPGM 5451), most probably not completely ossified (see the Material section). B, Proteus anguinus (BSPGM 4538). C, Speleomantes strinatii (MDHC 225), most probably not completely ossified (see the Material section). D, Salamandrina perspicillata (MDHC 407). E, Chioglossa lusitanica (MNCN 16099). F, Mertensiella caucasica (MNCN 23821). G, Salamandra salamandra (MDHC 396). From left to right: anterior, dorsal, lateral (right lateral for A–C, E, F; left lateral for D, G), posterior and ventral views. Scale bars: 1 mm.

Figure 9. Precaudal vertebrae of European urodeles. A, Salamandrella keyserlingii (BSPGM 5451). B, Proteus anguinus (BSPGM 4539). C, first precaudal vertebra of Speleomantes strinatii (MDHC 225). D, precaudal vertebra of Speleomantes strinatii (MDHC 225) close to the pelvis. E, Salamandrina perspicillata (MDHC 228). F, Chioglossa lusitanica (MNCN 16099). From left to right: anterior, dorsal, lateral (right lateral for A, C–F; left lateral for B), posterior and ventral views. Scale bars: 1 mm.

Figure 12. Caudal vertebrae of European urodeles. A, Salamandrella keyserlingii (BSPGM 5451). B, Proteus anguinus (BSPGM 4538). C, Speleomantes strinatii (MDHC 225). D, Salamandrina perspicillata (MDHC 407). E, Mertensiella caucasica (BSPGM 2730). F, Salamandra salamandra (MDHC 234). G, Salamandra salamandra (MDHC 396). From left to right: anterior, dorsal, lateral (right lateral for A, B, D–F; left lateral for C, G), posterior and ventral views. Scale bars: 1 mm.