Ptyas cf. mucosa ( Linnaeus, 1758 )

Lin, Chien-Hsiang, Lin, Si-Min, Chien, Chi-Wei, Lin, Te-En, Nazir, Haroon & Singh, Ningthoujam Premjit, 2025, First fossil frog and snake assemblage from southern Taiwan: a window into Pleistocene herpetofauna and palaeoenvironments in subtropical East Asia, Fossil Record 28 (2), pp. 293-308 : 293-308

Ptyas cf. mucosa ( Linnaeus, 1758)

Fig. 5

Material.

Two trunk vertebrae ( ASIZF 0101051 –1052).

Description.

In anterior view, the cotyle is rounded. In specimen ASIZF 0101052 , paracotylar foramina are present, located on the lateral margins of the cotyle, whereas in specimen ASIZF 0101051 , these foramina are not clearly visible. The prezygapophyses are well-developed, but the prezygapophyseal accessory processes are broken laterally. The zygosphene roof is dorsally convex and wider than the cotyle, with articular facets inclined dorsally. The neural canal is tunnel-like.

In posterior view, the condyle is circular, with height similar to width. The neural arch is depressed (vaulting ratio = 0.22–0.25). The zygantral area is deep and the paired endozygantral foramina are present.

In ventral view, the centrum is distinctly longer than wide and triangular in outline. A well-developed, oblanceolate haemal keel is present instead of a hypapophysis, almost reaching the condyle. Subcentral foramina are not clearly visible. The subcentral grooves are deep and long. Postzygapophyseal articular facets are oval. The paradiapophyses comprise a laterallysalient diapophysis and an almost flat parapophysis.

In dorsal view, the anterior edge of the zygosphene is straight with two small pointed lobes on the lateral sides. The posterior median notch is distinctly deep. Prezygapophyseal articular facets are oval.

In lateral view, the height of the neural spine is indeterminate in specimen ASIZF 0101051 due to poor preservation, whereas it is very high in ASIZF 0101052 . Both interzygapophyseal and subcentral ridges are distinct. Lateral foramina are present.

Remarks.

Although the prezygapophyseal accessory processes are only partially preserved, the remaining portions appear to be anteriorly directed. Combined with the large overall size of the vertebrae and the presence of distinct subcentral ridges with deep grooves, these features most closely match Ptyas mucosa , as described above. However, the poor preservation of both specimens — particularly the absence of epizygapophyseal spines, which may have been worn away — precludes a definitive assignment.

Figures

Figure 5. Ptyas cf. mucosa (ASIZF 0101051–1052) from the Middle Pleistocene Chiting Formation, southern Taiwan. A 1, B 1. Anterior view; A 2, B 2. Posterior view; A 3, B 3. Ventral view; A 4, B 4. Dorsal view; A 5, B 5. Lateral view. Scale bar: 5 mm.