Chelodina intergularis Fry, 1915

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

Chelodina intergularis Fry, 1915

Holotype: Australian Museum, Sydney ( AM R6255 ), Figure 1

Measurements. Straight carapacial length (midline) 193.3 mm; maximum carapacial width 136.4 mm; carapacial width at mid-bridge level 130.1 mm; maximum plastral length (from level of paired caudal tips to extreme anterior margin) 157.5 mm; midline plastral length 141.1 mm; plastral width at anterior extremity of bridge 72.0 mm; maximum posterior plastral width 68.8 mm; total shell depth at middle of bridge 70.6 mm.

Description. Specimen consists of a complete carapace with articulated plastron; all scutes have been removed and the specimen was highly polished during preparation. No ancillary skeletal components have been retained. The thoracic vertebrae have been lost, likely deliberately removed based on the damage to the rib heads. There is no evidence this specimen was cooked for consumption and was likely collected and prepared curatorially instead.

Dorsally there is an open space previously occupied by a 4 th neural bone (at the midline junction of the 3 rd and 4 th pleurals) which is four-sided and diamond-shaped (following Pritchard 1988; Thomson & Georges 1996); the neural itself was lost when its supporting thoracic centrum was removed. This neural shape is indicative of a breakthrough neural that occurs in occasional specimens of any chelid species that would normally not have any visible neural bones. The carapace is ovoid in shape, typical of Chelodina rugosa sensu lato (i.e., including C. kurrichalpongo and C. siebenrocki ). There is a reticulated pattern on the surface of the shell bone. Pleurals 1 through 5 have lateral fontanelles at the rib/gomphosis indicating this is not a fully grown individual. Based on size, growth and generalized shape, it is in all likelihood a subadult female. However, this is not certain.

The plastron is also complete and possesses a reticulated surface patterning resembling that of the carapace. This is a feature of Chelydera species. Unusually, the intergular scute is extended forwards and reaches the rim of the plastron. At the same time there is a slight indentation of the anterior edge of the plastron.

Inside the shell, there is significant damage to many rib heads; all the thoracic centra are missing. There is also a small hole drilled into the anterior vertebral arches where the bone sample for our analysis was taken. The pelvic suture insertion is square to oval in general shape and is significantly extending onto the 7 th pleural and pygal as well as completely crossing the 8 th pleural. This is the typical condition in C. rugosa sensu lato. The anterior bridge strut (for terminology, see Thomson et al. 1997) is enlarged and robust, angled back at approximately 45° and reaches the halfway point of the 1 st rib within the 1 st pleural. This is the typical condition of Chelydera species (compare Thomson 2000; Thomson et al. 2000) and excludes allocation of the holotype to the subgenera Macrochelodina or Chelodina .

Figures

FIGURE 1. Holotype of Chelodina intergularis, Australian Museum, Sydney (AM R6255). Photos: G. Shea.