Geminitor wenlockensis, Hyman & Köhler, 2022

Hyman, Isabel T. & Köhler, Frank, 2022, Homoplasy in shells discombobulated the taxonomy: revision of the larger helicarionid land snails of northern Queensland, Australia (Stylommatophora: Helicarionidae), Journal of Natural History 56 (41 - 44), pp. 1727-1799 : 1769-1771

Geminitor wenlockensis sp. nov.

( Figures 4 , 6 (f), 13)

Etymology

Named for the Wenlock River, one of Australia’s last remaining wild rivers. Much of the range of this species lies in the Wenlock River drainage sub-basin, with specimens (including the holotype) collected near several different river crossing points.

Material examined

Holotype. QM MO86000 , Wenlock R, c. 17.7 km N, on Peninusla Rd , Far North Qld, Australia (−12.3, 142.6), 18 September 1988, J. Stanisic, D. Potter, J. Chaseling.

Paratypes. QM MO21419 (same data as holotype) .

Other material. See Table 1 .

Diagnosis

External morphology. Shell ( Figure 6 (f)) small (SW 8–10 mm), pale amber, 5.5–6.1 whorls, subdiscoidal with a moderately elevated spire, whorls rounded; umbilicus narrow, sealed; protoconch with moderately coarse spiral grooves, becoming finer and more crowded on teleoconch. Body white (in alcohol). Mantle lobes small; shell lappets moderately large, triangular, tapering. Caudal horn moderately large.

Genital anatomy. Genitalia ( Figure 13 ) with short, slightly swollen vagina; bursa copulatrix moderately long, duct broad, internally with broad longitudinal pilasters basally, followed by transverse ridges and then wavy longitudinal pilasters, bursa oval. Free oviduct very long. Penis large, internally with two chambers, distal portion sculptured with two longitudinal pilasters, one large and raised, one flat; inner penial wall sculptured with longitudinal ridges distally, transverse ridges proximally; proximal portion sculptured with transverse wavy ridges arranged like petals around opening to epiphallus; distal portion longer than proximal portion; 40% enclosed in penial tunica. Epiphallus enters penis through small, beehive-shaped verge; epiphallus approx. equal in length to penis, epiphallus 2 similar in width to penis, gradually narrowing, epiphallus 1 narrower; epiphallus 1 longer than epiphallus 2; long epiphallic caecum present, with basal attachment of the penial retractor muscle; flagellum moderately short, slender, without obvious internal cryptae.

Remarks

This species was preliminarily identified as Helicarionidae CY 9 based on curatorial work. Geminitor wenlockensis ranges from the Portland Rd crossing of Wenlock River to Weipa in the west and Bramwell Junction in the north ( Figure 4 ). Some specimens of G. wenlockensis were misidentified in museum collections as the helicarionids Expocystis rusticus and Pravonitor kreffti . Expocystis rusticus is similar in appearance to G. wenlockensis , but can be distinguished by its much smaller size. It is also found farther south than G. wenlockensis , ranging from Cardwell to north of Cooktown and west to Mt Carbine and Chillagoe ( Stanisic et al. 2010). Pravonitor kreffti is similar in size and appearance, but can be distinguished from G. wenlockensis by its much larger size, and is also found farther north, from Cape York to the Inner and Near Western Torres Strait Islands. There is a stronger similarity between G. wenlockensis and P. septentrionalis , another Cape York species, which is more similar in size but differs in its less glossy shell surface, unsealed umbilicus and more defined columellar thickening.

Figures

Figure 4. Distribution map. Grey symbols: Geminitor. Blue symbols: Pravonitor. Red symbols: Elatonitor. Biogeographic barriers are marked in black; A = Normanby Basin, B = Black Mountain Corridor, and C = Atherton Tableland.

Figure 6. Shells of Geminitor. a) Geminitor laura, AM C.474954, Lakeland Downs. b) Geminitor villaris, QM MO20887, Mt Cook. c) Geminitor villaris, QM MO21256, Starcke. d) Geminitor kullaensis, QM MO30875, McIlwraith Range. e) Geminitor macveae, QM MO20694 (paratype). f) Geminitor wenlockensis, QM MO86000 (H), Wenlock River. Scale bar: 5 mm. Photographs by F. Köhler ((a-b), d, f), J. Caiza (c), and G. Thompson (e).

Figure 13. Genitalia of Geminitor wenlockensis, QM MO86000 (holotype), Wenlock River. a) Reproductive system. b) Penis interior. Arrows mark the boundaries of the upper penial chamber. Scale bars: 1 mm.