Geminitor laura ( Stanisic, 2010 )

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 : 1758-1762

Geminitor laura ( Stanisic, 2010)

( Figures 4 , 6 (a), 7(a–c), 8(a), 9)

Pravonitor laura Stanisic, 2010: 300–301 .

Material examined

Holotype. QM MO53669 , Palmerville Stn , SSE on Maytown Rd , Far North Qld, Australia (16.047°S, 144.214°E), among limestone rock, 17 December 1996, L. Little.

Paratypes. QM MO61204 , QM MO61357 , QM MO61431 , QM MO61701 , QM MO61763 , QM MO62896 , QM MO78932 , AM C .425417.

Other material. See Table 1 .

Diagnosis

External morphology. Shell ( Figures 6 (a), 7(a–c)) medium-sized (SW 11.6–14.6 mm), golden amber, 5.5–6.3 whorls, discoidal with a low to moderately elevated spire, whorls rounded; umbilicus narrow, sealed; protoconch with moderately coarse spiral grooves, becoming finer and more crowded on teleoconch. Body ( Figure 8 (a)) pale brown with grey tail tip and black eyestalks. Mantle lobes small; shell lappets moderately short, narrow, tapering. Caudal horn moderately large.

Genital anatomy. Genitalia ( Figure 9 ) with very short vagina; bursa copulatrix moderately long, duct broad, internally with transverse ridges, bursa elongate. Penis large, internally with two chambers, distal portion sculptured with two distinct longitudinal pilasters; proximal portion sculptured with transverse rounded plates arranged like petals around opening to epiphallus; approx. 75–100% enclosed in penial tunica. Epiphallus enters penis through a small, fragile verge; epiphallus longer than penis, epiphallus 2 similar in width to penis, gradually narrowing, epiphallus 1 narrow; boundary between penis and epiphallus 2 indistinguishable; epiphallus 1 slightly longer than epiphallus 2; long epiphallic caecum present, with basal attachment of the penial retractor muscle; flagellum moderately long, slender, without obvious internal cryptae.

Remarks

Geminitor laura was described from Palmerville, and ranges north to the Laura Basin and east to near Cooktown, Far North Qld, in dry vine thicket and adjacent woodland ( Stanisic et al. 2010). We extend the range herein to include populations from farther south at Mt Elephant ( Figure 4 ). Considerable genetic variation was observed within this species, as with some other northern Qld helicarionids that exhibit broad ranges (e.g. P. aquilonia ). However, anatomical differences were slight at most, and given the paucity of data, we choose to retain all populations in G. laura at the present time.

Geminitor villaris , G. macveae , and G. cf kullaensis are found in very close proximity to G. laura , although no sympatry is recorded. Geminitor laura can be distinguished from these species by its significantly larger size, and anatomically by the lack of a penial verge in either chamber of the penis.

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 8. Live animal images. a). Geminitor laura, Black Mountain. b). Geminitor villaris. c). Pravonitor aquilonia, AM C.524931, Bellenden Ker. d). Pravonitor aquilonia, Cape Tribulation. e). Pravonitor aquilonia, AM C.524981, Mossman Gorge. f). Elatonitor suturalis, Wooroonooran NP. Images not to scale. Photographs by Adnan Moussalli (a, d, f), Frank Köhler (c, e) and Queensland Museum (b).

Figure 9. Genitalia of Geminitor laura, AM C.553551, Black Mountain. a). Reproductive system. b). Penis interior. Scale bars: 1 mm.