Bohra sp.

Prideaux, Gavin J. & Warburton, Natalie M., 2023, A review of the late Cenozoic genus Bohra (Diprotodontia: Macropodidae) and the evolution of tree-kangaroos, Zootaxa 5299 (1), pp. 1-95 : 66-67

Bohra sp. indet. 1

Bohra sp. : Hocknull (2005a), p. 26, figure 1B,C. Hocknull (2005b), p. 86.

Bohra sp. indet.: Prideaux & Warburton (2008), pp. 463–464, figure 1; partim. Prideaux & Warburton (2009), p. 166, figure 1; partim.

Referred specimens. Chinchilla Rifle Range (site not specified), Queensland. QM F58666, right calcaneus; QM F49453, right calcaneus. Collected by Doris and Cecil Wilkinson.

Unit C/D, QM L1311C/D, Speaking Tube Cave, western side of Mount Etna near Rockhampton, Queensland. QM F51762, right adult calcaneus. Retrieved by S. Hocknull and others from cave fill exposed by a mining operation ( Hocknull 2005b).

Description and comparisons. Calcaneus. Three calcanei very similar in absolute size and morphology are referred to Bohra sp. indet. 1, the most complete of which is QMF51762 ( Figure 34E–H ). The calcaneus is broad, stout and dorsoventrally flattened, with transversely broad articular surfaces and rugose ligament insertions.The tuber calcanei is broad and flared caudally, particularly on the lateral side of the epiphysis ( Figure 34E–F, I–J ). The broad, rugose plantar surface is laterally flared cranially, giving an impression of an oblique alignment of the long axis, although this is less pronounced in QM F49453. The anterior plantar tubercle is small and the transverse sulcus is only very slightly oblique from medial to lateral sides, and moderately wide and shallow ( Figure 34E ). The sustentaculum tali is extended medially, moderately long craniocaudally, and gently convex ( Figure 34G, L ). The flexor groove running over the sustentaculum is very shallow, particularly in QMF49453; the flexor groove is deeper and more distinct in QMF58666. The medial and lateral talar facets are conjoined, though with distinct margins. The lateral facet is tapered medially ( Figure 34A–B, E–F, I–J ). The caudal margin of the oval medial facet is projects dorsally, and the articular surface is slightly expanded on the dorsal surface toward the base of the calcaneal tubercle. The fibular facet is abraded to varying degrees in all specimens, but appears to be relatively small. The sulcus for the posterior calcaneofibular ligament is deep, and the tubercle and sulcus for the anterior calcaneofibular ligament are laterally expanded and rugose. The scar for the ligament of the talar head is moderately deep. The calcaneocuboid articulation is transversely broad and dorsoventrally compressed in cranial view. The step between the rather rectangular dorsomedial and dorsolateral facets is obliquely aligned and moderately smoothed ( Figure 34E–F ), and the ventromedial facet is reduced and smoothly continuous with the dorsal facets.

The Bohra sp. indet. 1 calcaneus is 15% larger in absolute size than in B. nullarbora and B. planei , but most similar in overall proportions to B. planei ( Table 8 ). The rugose plantar surface most closely resembles that of B. nullarbora . The anterolateral tubercle is less prominent than in B. wilkinsonorum and B. planei . The transverse sulcus is most similar to that of B. paulae . The sustentaculum tali is longer than in B. paulae , but not as long or wide as in B. wilkinsonorum and B. planei . The very shallow flexor groove of QM F49453 is more similar to the conditions observed in B. illuminata , B. nullarbora and, particularly, B. paulae . The groove is deeper in B. wilkinsonorum and B. planei . The abutting talar facets are conjoined, as in B. paulae and species of Dendrolagus , but are not as smoothly confluent as in B. planei . By contrast, the facets are distinctly separate in B. wilkinsonorum and B. nullarbora . The ventromedial cuboid facet is more confluent with the dorsomedial portion than in B. nullarbora , B. wilkinsonorum and B. planei , though the former is not reduced and the calcaneocuboid step is not smoothed to the extent seen in B. paulae and species of Dendrolagus .

Remarks. It is possible that the few slight differences in morphology between the three calcanei referred to Bohra sp. indet. 1 indicate that they belong to different species. Yet, they more closely resemble each other than any other species of Bohra in calcaneal morphology. Unfortunately, much of the taxonomically diagnostic cuboid articulation is broken off of the two Chinchilla LF specimens. Clearly, they cannot belong to B. wilkinsonorum , because its calcaneus is much larger and morphologically very distinct. However, teeth or tooth-bearing remains within a size range commensurate with that of these calcanei are known for B. bila and B. sp. cf. B. bandharr from the Chinchilla LF. In all probability, the calcanei referred to Bohra sp. indet. 1 belong to one or the other of them.

Figures

FIGURE 34. Calcanei (adult, right) of Bohra sp. indet. 1. QM F49453. A: plantar view. B: dorsal view. C: medial view. D: lateral view. QM F51762. E: plantar view. F: dorsal view. G: medial view. H: lateral view. QM F58666. I: plantar view. J: dorsal view. K: lateral view. L: medial view.