Chelodina rugosa Ogilby, 1890

Kehlmaier, Christian, Kuchling, Gerald, Shea, Glenn, Georges, Arthur, Zhang, Xiuwen, Fritz, Uwe & Thomson, Scott, 2024, History and historical DNA: Identity of Chelodina intergularis Fry, 1915 and type localities of C. intergularis and C. rugosa Ogilby, 1890, Zootaxa 5448 (4), pp. 531-555 : 542-544

Chelodina rugosa Ogilby, 1890

Holotype: Australian Museum, Sydney ( AM R6256 ), Figure 3

Measurements. Straight carapacial length (midline) 255.8 mm; maximum carapacial width 171.7 mm; carapacial width at mid-bridge level 160.0 mm; maximum plastral length (from level of paired caudal tips to extreme anterior margin) 211.4 mm; midline plastral length 191.7 mm; plastral width at anterior extremity of bridge 95.7 mm; maximum posterior plastral width 92.9 mm; total shell depth at middle of bridge 93.9 mm.

Description. Specimen consists of a complete carapace and articulated plastron, the anterior thoracic centra are in situ as well as the posterior pelvis. Preserved separately are the 7 th and 8 th cervical vertebrae. The scutes are in situ with this specimen. This specimen was clearly either collected alive or found recently deceased and then prepared curatorially for the museum. The entire carapace has a fine reticulate pattern to the scutes which is more rugose and antero-posteriorly aligned in the 2 nd to 4 th vertebral scutes. This pattern is typical of C. rugosa sensu lato as defined above.

The 4 th vertebral scute is reduced in size compared to other specimens of C. rugosa , with an extra scute between this and the 5 th vertebral which is also reduced. Between the 1 st costal on the left side and the 1 st vertebral scutes there is an extra anomalous scute which has encroached into the normal size and shape of both scutes that border it. The 2 nd marginal is approximately 30% longer than the 3 rd, otherwise marginals appear normal in growth (note damage left side below) and number 11 on each side. A pygal scute and cervical scute are also present.

At the left side rear quarter of the carapace there is significant damage above the hind leg. This would appear to be the result of a bite from a predator. This damage has fully healed with overgrown scute material and hence occurred many years before the death of the animal.

The plastron is complete, includes the attached posterior pelvis, and also has a fine reticulate pattern throughout. The museum accession number (R 6256) is written in permanent ink on the left humeral scute. There is some old larger-font-sized handwritten text on the plastron, twice “Cape York ” in different orientations, one longitudinal, one transverse. The transverse inscription also has “Thorpe,” additional text is present but illegible. On the left rear of the plastron, within the anal scute, is a break where some bone has been lost, interestingly it is in a similar position to the injury of the carapace. There is evidence of some healing, and hence the injury occurred before the animal died. However, the plastral fracture is far less healed over than the carapace injury, indicating that the plastral damage occurred later.

The scute pattern of the plastron is typical of C. rugosa sensu lato. Importantly, this includes the shape, size and extent of the intergular scute. This scute is large, hexagonal though elongated. It partially divides the humerals and separates the pectorals. It is enclosed anteriorly by the gular scutes, which is the typical Chelodina condition. There is a small indentation between the epiplastra/gulars at the anterior of the plastron.

Internally, the first four thoracic centra are present.The 4 th thoracic centrum is articulated and damaged anteriorly, the other thoracic centra seem to have become disarticulated over time, or during preparation, but were not cut out as the rib heads are largely undamaged. This differs from the C. intergularis type where the centra were removed during preparation as indicated by the extensive rib damage. The pelvis is postero-laterally rotated (sensu Thomson et al. 2023) and attached to the 1 st and 2 nd sacral ribs (ribs 10–11) which are in situ. The pelvis covers the 8 th pleural and extends onto both the 7 th pleural and the pygal.

Figures

FIGURE 3. Holotype of Chelodina rugosa, Australian Museum, Sydney (AM R6256). Photos: G. Shea.