Salamandra, GARSAULT, 1764

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 : 593-595

SALAMANDRA GARSAULT, 1764

S p e c i e s: S a l a m a n d r a a t r a * L a u r e n t i, 1 7 6 8, Salamandra corsica , Salamandra lanzai * Nascetti, Andreone, Capula & Bullini, 1988 and Salamandra salamandra * (Linnaeus, 1758) .

Otic–occipitum complex ( Fig. 4E )

The prominentia semicircularis anterioris is covered by the high parietal crest, whereas the prominentiae semicircularis posterioris and lateralis are rounded and easily recognizable. Among the prominentiae, a deep middle depression shows no foramina in its floor. The prominentia semicircularis posterioris is not extended posteriorly and ventrally between the cotyle and the parotic process. The circular fenestra ovalis is almost perpendicular to the vertical, and its anterior edge is anterior to the mid-length of the complex. The high parietal crest begins from slightly posterior to the mid-length of the distal edge of the tectum synoticum and extends obliquely on the tectum synoticum and on the prominentia semicircularis anterioris until the anterior end of the otic process. It is higher anteriorly, with its anterior tip forming an angle of 70–90° with the vertical. The parotic crest starts from the dorsolateral edge of the cotyle, extends along the lateral edge of the prominentia lateralis and meets the parietal crest in the anterior part, forming a variable angle. The parotic process is represented by a small tip, although it can be absent in some cases. In more detail, the parotic crest can be interrupted or not, depending on the position of the fenestra ovalis; when the fenestra ovalis has a dorsal position, the parotic crest is interrupted in its middle part, and the parotic process is not present (e.g. in MNHN 1888.651). The parotic crest is developed variably between the parotic process and its anteriormost part and, in some specimens, it is absent in this area (e.g. in the left capsule of HNHM 2001.75.24). The tectum synoticum is enlarged distally, and its anterior edge in medial view is posterior to the midlength of the complex.The tectum synoticum is extended medially beyond the prefacial commissure, but a small concavity is visible between them. The tectum is almost as medially extended as the hypochordal commissure. The postoticum foramen is elliptical, with the vertical major axis being not much longer than the minor one, and surrounded posteriorly by the lamina of the tectum synoticum and the cotyle. The articular surfaces of the otic process and of the processus basalis are kidneyshaped and separated by a deep sulcus petrosus. The otic process is slightly more developed anteriorly than the processus basalis, forming a short, irregular anterior process. The basicapsular commissure is extended slightly medially beyond the prefacial one, and the foramen prooticum is not surrounded by bone. The auditory cavity is deep, with isolated foramina for the different branches of the acoustic nerve. In ventral view, a low medial crest runs along the medial side of the ventral surface of the complex. The crista retrosellaris between the basicapsular and hypochordal commissures occupies most of the fenestra basicranialis, leaving only a small triangular concavity close to the hypochordal commissure. The ventral surface is smooth or bearing a couple of foramina, with the sulcus carotis not reaching the low medial crest.

Remarks: In the right complex of HNHM 2001.75.24, the parietal crest is less developed than in the other specimens.

Atlas ( Fig. 6G )

The neural canal is generally triangular or subtriangular in anterior view and is as high as each occipital joint. In posterior view, the neural canal is slightly wider than the cotyle; the cotyle is elliptical, with the major axis being horizontal. The occipital joints are circular or elliptical, with the minor axis being horizontal (or sub-horizontal). 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. The neural crest is low and thick or blade-like, starts posterior to the anterior edge of the neural arch and is posteriorly forked, and in lateral view, it is horizontal or gently concave. The secondary crests are parallel to the anterior edge of the neural arch (running transversely across the neural arch roof), and their posterior end corresponds to the anterior margin of the neural crest. In lateral view, these crests can or cannot cover the anterior edge of the neural arch. The neural spine can be present or absent. The lateral surface of the atlas bears more than one foramen per side. The incisura vertebralis cranialis is wide and does not contact the occipital joints. In lateral view, the dorsal edge of the neural arch is strongly inclined, forming an angle of 50–60° relative to the horizontal axis. The neural arch between the incisura caudalis and the cotyle is inclined or concave. The maximum concavity of the incisura vertebralis caudalis lies almost in the horizontal plane containing the maximum concavity of the incisura vertebralis cranialis. The low lateral crests do not reach the elliptical postzygapophyses. The inferior crests are low. In posterior view, the neural arch is dorsally convex (inverted U-shaped). Less than one-third of the postzygapophyses extends posteriorly beyond the cotyle in lateral view. In dorsal view, the neural arch is anteriorly straight or concave (V-shaped concavity), and the incisura dorsalis (formed by the neural arch) can be observed posteriorly. The cotyle may or may not be visible in dorsal view. The ventral surface is smooth or bears more than two foramina.

Remarks: The lateral crests are only slightly visible in HNHM 2001.78.4. The neural crest is thicker (and flat) in the anterior part (almost until the midlength of the spine) and thinner (and blade-like) in the posterior part in the specimens from MNHN. In MNHN 1888.651, the neural crest is not horizontal in lateral view, but a dorsal concavity is formed by a thick anterior tuberculum and a rounded, blade-like posterior lamina. In dorsal view for MDHC 227, the neural crest and secondary crests are hourglassshaped. In MDHC 234 ( Salamandra salamandra ) and MDHC 394 ( Salamandra atra ), in lateral view, the incisura cranialis is strongly ventral and contacts the occipital joint. In MDHC 394, the neural crest is not posteriorly bifurcated. In all specimens of Salamandra lanzai , the cotyle is ventral to the rest of the centrum. In MDHC 361 and MDHC 363, the lateral crests reach the postzygapophyses.

Precaudal vertebrae ( Fig. 10B–D )

The precaudal vertebrae are opisthocoelous and not elongate (length approximately equal to width). Most of the height of the vertebra is formed by the centrum and neural arch ventral to the postzygapophyses (only one-fifth of the height of the vertebra is formed by the neural arch dorsal to the postzygapophyses). The neural canal is triangular, slightly higher or lower than the condyle. The condyle is elliptical, with a horizontal major axis. In lateral view, the anterior edge of the neural arch between the condyle and the elliptical prezygapophyses is weakly inclined. Diapophyses and parapophyses are distinguishable, connected by a smooth lamina that may or may not reach their distal ends. The transverse processes exhibit strong posterior orientation and may or may not cover parts of the incisura caudalis in lateral view. In the same view, the neural arch dorsal to the elliptical prezygapophyses is rarely visible and is, where visible, vertical. The neural crest starts posterior to the line connecting the posterior edge of the prezygapophyses. It is high in the first two or three vertebrae, then lower in subsequent vertebrae.The short neural spine is generally present. The vertebrae are dorsoventrally compressed and broad in dorsal view, but the anterior and posterior zygapophyseal crests are poorly distinguishable and only slightly visible in lateral view. The ventral crests are generally present and parallel. The posterior ventral crests are poorly developed, and they do not reach the posterior edges of the cotyle. The ventral lamina is, thus, triangular, trapezoidal or asymmetrically rhomboidal. The lateral surface of the vertebrae generally bears at least two concavities per side and foramina in variable numbers. In anterior view, a small foramen is visible at the base of the parapophyses. In lateral view, the dorsal edge of the neural arch is horizontal anteriorly or dorsally concave. The incisura vertebralis caudalis is deep and generally reaches the centrum.Alternatively, the incisura and the centrum can be separated by a posteriorly convex portion of the neural arch. In posterior view, the dorsal edge of the neural arch is horizontal or dorsally concave, in this case forming a small, V- or U-shaped incisura dorsalis. In lateral view, the neural arch dorsal to the postzygapophyses is vertical or sinusoidal in lateral view. Less than one-third of the postzygapophyses is extended posteriorly beyond the cotyle in lateral view. In dorsal view, the neural arch is anteriorly concave (U-shaped). Most of the length of the condyle is visible in dorsal view, whereas the cotyle is not visible (or only in part, through the incisura dorsalis). The ventral surface is generally perforated.

Caudal vertebrae ( Fig. 12F, G )

The caudal vertebrae are not particularly high (height/ length ratio <1.25). The neural and haemal canals are elliptical. The neural canal is wider than the haemal canal. The neural canal is as high as the haemal canal. In the first caudal vertebrae, the transverse processes are transformed into a vertical lamina, rectangular in anterior view, and they become horizontal or absent in the last caudal vertebrae. The neural and haemal crests are both generally low or, if high, only along their mid-length. The haemal crest does not project anteriorly beyond the haemal arch. Zygapophyseal and ventral crests are visible only as low knobs. Anterior and posterior zygapophyseal crests are subhorizontal or ventrally concave. The posterior ventral crests start from the ventral edge of the haemal arch, a bit anterior to the posterior edge of the arch. In lateral view, anterior and posterior ventral crests form an angle> 130°. The anterior ventral crests do not project anteriorly beyond the haemal arch. The lateral surface has a single large foramen on the haemal arch or one additional foramen on the lateral surface of the neural arch. In lateral view, the anterior ventral crests are anteriorly close to the centrum, such that the anterior edge of the haemal arch between the centrum and the anterior ventral crest is not visible; ventral to the anterior ventral crests, the anterior edge of the haemal arch is inclined posteriorly. The posteroventral edge of the haemal arch forms a sharp tip in lateral view. The haemal arch is forked in ventral view.

Remarks: In ventral view of the HNHM specimens and in some vertebrae of MDHC 234, the haemal crest posteriorly follows the bifurcation of the haemal arch, with two low crests, and shows a small foramen at the point where it is bifurcated; this is not the case in the other specimens. In MDHC 394 ( Salamandra atra ), the haemal crest is higher than the neural crest, and in some vertebrae it is as high as the posterior half of the haemal arch.

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 10. Precaudal vertebrae of European urodeles. A, Mertensiella caucasica (MNCN 23821). B–D, Salamandra salamandra (MDHC 396): B, one of the first trunk vertebrae; C, trunk vertebra close to the pelvis; and D, sacral vertebra. E, Calotriton asper (MNCN 16122). From left to right: anterior, dorsal, lateral (right lateral for B, D; left lateral for A, C, E), 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.