Pravonitor aquilonia ( 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 : 1777-1778

Pravonitor aquilonia ( Stanisic, 2010)

( Figures 4 , 7 (d–f), 8(c–e), 14(c), 16)

Malandena aquilonia Stanisic, 2010: 296–297 .

Material examined

Holotype. QMMO48605, Mount Halcyon , north-eastern Qld, Australia, (16°03ʹS, 145° 25ʹE), rainforest, 870 m, under logs, 22 November 1993, G. Monteith, H. Janetzki, D. Cook.

Paratypes. QMMO48640, QMMO48702, QMMO48711, QMMO48720, QMMO48731, QMMO78928, AM C .103690, AM C.104275, AM C.425105, AM C.425108.

Other material. See Table 1 .

Diagnosis

External morphology. Shell ( Figures 7 (d–f), 14(c)) large (SW 15.1–21.2 mm), pale gold to amber, sometimes with an amber supraperipheral band, just visible at suture, 5.2–5.8 whorls, subglobose with a subangulate to rounded whorl profile and a moderately raised spire; shell microsculpture of very fine spiral grooves on the protoconch and fine spiral grooves on the teleoconch; umbilicus narrow, sealed with a mucous plug, partially covered by reflected lip. Body ( Figure 8 (c–e)) pale brown, sometimes flecked with pale pigment; tip of caudal horn slightly darker; eyestalks dark. Mantle lobes moderately small; shell lappets moderately long, narrow, tapering. Caudal horn large.

Genital anatomy. Genitalia ( Figure 16 ) with short vagina, internally with longitudinal pilasters; bursa copulatrix moderately long, duct broad at base, internally sculptured with wavy longitudinal pilasters, then narrowing, narrow portion sculptured internally with longitudinal pilasters; bursa elongate. Penis broad, internal wall sculptured with pustules, smaller proximally, becoming larger and often pyramid-shaped distally, sometimes fused to form longitudinal ridges basally; approx. 80–100% enclosed in penial tunica. Epiphallus enters penis through a small verge, slightly laterally, leaving a small to moderately small blind penis tip; epiphallus longer than penis; epiphallus 2 longer than epiphallus 1; long epiphallic caecum present, with medial attachment of the penial retractor muscle; flagellum long, slender, containing no obvious internal cryptae. Spermatophore simple, consisting of soft capsule with elongate tip and long, slender tail-pipe sculptured with two rows of very fine, short, hair-like spines.

Remarks

Pravonitor aquilonia was first described as a member of the genus Malandena ( Stanisic et al., 2010) . In the current study we demonstrate that it groups with Pravonitor rather than Malandena based on both genital morphology and mitochondrial DNA. This large snail is recorded from rainforest and vine thicket from Mossman Gorge to Cooktown ( Stanisic et al. 2010). Specimens examined in the present study ranged from Mt Carbine to Cape Tribulation. Specimens from Malanda and Mt Father Clancy, preliminarily identified as Elatonitor suturalis or P. monteithi , were shown to belong to P. aquilonia based on morphological and/or molecular data, extending this species’ known range southwards ( Figure 4 ). The figured syntype of Elatonitor suturalis (herein designated as lectoctype) is from Malanda, so the two species are likely to be sympatric at this location.

Despite its removal to the genus Pravonitor , P. aquilonia shows a strong similarity to the sympatric E. suturalis . The two species are similar in size and shape, but can be most easily distinguished by the presence of coarse spiral grooves on the teleoconch of E. suturalis , visible on both the upper and lower sides of the shell. There is also a strong similarity and probably also a close relationship between P. aquilonia and the sympatric P. monteithi . However, P. monteithi is significantly smaller than P. aquilonia . In the northern part of its range, P. aquilonia is parapatric with G. laura , but can easily be distinguished by its much larger size and more globose shape.

There was considerable interspecific variation seen within P. aquilonia , including between specimens from a single location (e.g. Mossman). This has also been observed in other Australian helicarionids with broad ranges (e.g. Geminitor laura , this study; Fastosarion alyssa, Hyman and Köhler 2019a ; Helicarion cuvieri, Hyman and Köhler 2018a ). Few specimens were available for the current study, however, and further studies with more dense sampling would be of great benefit in clarifying the species boundaries, particularly the relationship with P. monteithi .

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 7. Shell microsculpture. a–c). Geminitor laura, AM C.553551, Black Mountain. d–f). Pravonitor aquilonia, AM C.553561, SE of Malanda. g–i). Elatonitor suturalis, QM MO76507, NE of Babinda. Scale bars: b, e, h = 200 µm; a, c, d, f, g, i = 500 µm. Photographs by Sue Lindsay.

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 16. Genitalia of Pravonitor aquilonia. a, f) QM MO24773, Mt Lewis. b-e) AM C.533529, Cape Tribulation. a) Reproductive system. b) Spermatophore. c) Penis with tunica opened. d) base of reproductive system. e) Penis interior. f) Penis interior. Scale bars: 1 mm.