Morphological examinations and analyses of shell dimensions aimed at documenting and evaluating the amounts of morphological differentiation within and between operational units identified in the mitochondrial phylogeny. In general, shells of Kimberleytrachia can be readily distinguished from those of most other camaenids by a combination of key characters, such as being transparent and brittle, often comparatively large, weakly elevated, having an open umbilicus and being covered by microscopic pustules, often also periostracal projections (setae). In conjunction with the shell, Kimberleytrachia is characterised by a combination of genital features, including the lack of penial sheath and verge and the presence of an epiphallus with flagellum. A peculiarly complex inner penial wall sculpture and frequent presence of a pad-like swelling underneath the opening to epiphallus are distinctive features of this genus. The general configuration of the genital organs is identical in all species of Kimberleytrachia while in particular details of the sculpture of the inner penial wall are species specific.
The shells of species described below differed to varying degrees in shape, sculpture and periostracal microsculpture (Figs 4, 5, 6, 7, 8 in Appendix): Kimberleytrachia leopardus n. sp., K. nelsonensis n. sp. and K. serrata n. sp. differ from the other new species by their lower spire (Table 2), while K. jacksonensis n. sp., K. setosa n. sp. and K. silvaepluvialis n. sp. have more elevated spires (Table 2). Periostracal setae were observed on shells of K. jacksonensis n. sp., K. nelsonensis n. sp. and K. setosa n. sp., whereas K. leopardus n. sp. and K. silvaepluvialis n. sp. exhibited a combination of pustulation and axial sculpture; K. serrata n. sp. exhibited a peculiar teleoconch microsculpture of ‘saw-teeth-shaped’ periostracal projections (Fig. 7C in Appendix), readily distinguishable from that observed in the other species. Generally, the species varied little in their apertural and umbilical morphology as well as shell colour (yellowish-brown).
The examined species exhibited a rather conserved genital anatomy. Generally, species varied little in the relative lengths of penis, epiphallus, flagellum and free oviduct. The inner penial wall consistently revealed a combination of transverse lamellae and longitudinal pilasters and a pad-like swelling at the distal part of the penial wall. The shape, size and arrangement of sculptural elements of the inner penial wall were species-specific (see descriptions in the Appendix).
The genital anatomy of Succochlea n. gen., in particular the sculpture of inner penial wall (Fig. 10B in Appendix), was highly similar with Kimberleytrachia except for its much longer vagina. Unlike Kimberleytrachia, Succochlea n. gen. had no deflected aperture, an extremely reduced apertural lip without basal nodule, no periostracal projections or pustulations. Instead, the protoconch exhibited a distinctive sculpture of radial ridgelets not known from Kimberleytrachia (Figs 4G, 8D-F in Appendix).