Pseudotricula conica, Ponder & Clark & Eberhard & Studdert, 2005

Ponder, W. F., Clark, S. A., Eberhard, S. & Studdert, J. B., 2005, A radiation of hydrobiid snails in the caves and streams at Precipitous Bluff southwest Tasmania, Australia (Mollusca: Caenogastropoda: Rissooidea: Hydrobiidae s. l.),, Zootaxa 1074 (1), pp. 1-66 : 30-34

Pseudotricula conica n.sp.

Figures 3J–L ; 4E ; 6E–G ; 7F–I ; 8D, E ; 9A, D ; 10F, G ; 12B–D ; 13A–F .

Type material

Holotype: AMS C.439649, Cane Toad Abuse Streamway Damper Cave , stn PB1–2A, 28 Mar 1994.

Paratypes: AMS C.203676, Damper Cave , same locality, stn PB1–2A (10 dry, 20+ wet) ; QVM, 9:20539 (5 wet).

Other material examined (all AMS)

Bauhaus: C.201823, main streamway, stn PB6­1A, 14 dry); C.201824, same locality, stn PB6­1A (14 dry); C.201460, Screaming Stals streamway, stn 12 (2 dry, 17wet); C.201459, Screaming Stals streamway, stn 11 (12 dry, 20+ wet); C.201469, same locality, stn 13 (3 dry); C.439498, same locality, stn 12 (2 dry); C.201813, Persephone Pot, stn PB17­2a.2, middle and upper streamway (9 dry); C.201817, same locality, stn PB17­2.1, lower streamway (20+ dry, 20+ wet); C.439650, same locality, stn PB17­2a.1 (1dry) figured specimen; C.439496, Persephone Streamway, stn 8 (4 dry); C.439501, same locality, stn 9 (2 dry); C.439499, same locality, stn 9 (1 dry); C.439500, same locality, stn 10 (3 dry).

Damper Cave: C.203692, stn PB1­1B (1 dry, 3 wet); C.201488, main streamway, stn 6 (9 dry, 16 wet); C.203680, main streamway near entrance, stn PB1­1A (20+ dry, 20+ wet); C.439652, same locality, stn PB1­1A, (1dry), figured specimen; C.201464, Cane Toad Abuse streamway, stn 2 (11 dry, 20+ wet); C.201487, same locality, stn 2 (4 dry, 4 wet); C.201470, stn 2 (6 dry); Cueva Blanca: C.166967, no stn no. (2 dry, 6 wet); C.203694, Black Curtain Streamway, stn PB4­1C (5 dry).

Etymology

Conicus Latin adjective, cone­shaped; refers to the conical shape of the shell of this species.

Description

Shell ( Figs 6E–G ; 12B–D ; 13A–F ). Length up to 3.2 mm (usually less than 3 mm, mean 2.3 mm); conical to broadly conical (SW/SL 0.58–0.75, mean 0.67, n = 60); spire low to moderate, straight to slightly convex in outline; last whorl evenly rounded, or angular to subangular in middle of whorl; whorls very slightly convex; suture simple. Protoconch microsculpture of small, distinct, closely spaced pits ( Fig. 6E, F ). Teleoconch up to 3.3 whorls in adult; aperture oval to pear­shaped; moderately large, shorter to longer than spire (AL/SL 0.40–0.60, mean 0.50, n = 60); outer lip prosocline, straight, with or without slight reflection; external varix absent; posterior notch absent; inner lip thin to moderately thickened and narrow to medium width, firmly adhering to narrowly separated from parietal wall. Shell colour white or yellowish­brown to pale brown.

Dimensions. See Table 8.

Operculum ( Fig. 7F–I ). Yellowish; inner surface with white smear.

Pallial cavity ( Fig. 8D, E ). Ctenidium narrow; 10–14 very small filaments; osphradium between posterior end and middle of ctenidium; hypobranchial gland thick; renal organ extends forward ca. ⅓–½ into pallial cavity; pericardium more than ½ in pallial roof.

Radula ( Fig. 3J–L ). Central teeth: dorsal edge with moderate to deep indentation; 5 lateral cusps, median cusp of narrow to medium width, bluntly to sharply pointed, less than twice as long as adjacent cusps. Lateral teeth: dorsal edge lightly convex to moderately indented; with 4–7 cusps on outer and 4–6 on inner side; median cusp of medium to narrow, sharp to blunt, less than twice as long as adjacent cusps; ratio of cutting edge to shaft about ⅓; basal projection bluntly pointed. Marginal teeth: Inner with 21–32 cusps; outer with 22–32 cusps.

Stomach ( Fig. 9D ). Stomach with posterior chamber and anterior chamber about equal in size.

Male genital system. Testis of 1.25 whorls; prostate gland oval to elongate pyriform; compressed in section. Pallial vas deferens straight. Penis ( Fig. 4E ; 9A ) with weak swelling in mid­distal portion; distal end long, papilla­like; medial section parallel sided; of medium length; penial duct in medial section straight to undulating; base of penis moderately wide; with weak to moderate folds; penial duct straight to undulating.

Female genital system ( Fig. 10F, G ). Ovary of 0.6–1.0 whorls; oviduct extends to posterior edge of bursa copulatrix or slightly anterior or posterior to edge; straight distal to seminal receptacle; joins bursal duct in front of posterior pallial wall about half way between posterior pallial wall and capsule gland to about junction of albumen and capsule glands. Bursa copulatrix large, extending to posterior pallial wall or into pallial roof; elongately oval to pyriform; with bursal duct arising from middle of anterior edge of bursa or from antero­ventral edge; straight or with undulations. Seminal receptacle at middle of inner wall of bursa copulatrix or near mid ventral edge; ovoid to pyriform. About ½ to more than ½ of albumen gland in front of posterior pallial wall; capsule gland about same length as albumen gland to about ⅓ length of albumen gland; compressed oval in section; anterior end tapering to blunt; ventral channel simple, approximately parallel­sided throughout; vestibular area indistinct; genital opening overlapping anterior end of capsule gland.

Distribution and habitat

This is one of the commonest and widely distributed species in the caves. It appears to prefer low energy streams with mixed substrates, although a few specimens have been found in high energy habitats, notably in Cueva Blanca.

Remarks Pseudotricula conica exhibits considerable variation in shell size and shape in what we have interpreted as a single species. In particular, samples from Cueva Blanca and Bauhaus caves are fairly consistently elongate (e.g., Fig. 12D ; 13A, C ), while those from Damper Cave are usually broader ( Fig. 12B, C ; 13D–F ). At least some material from the latter cave shows a range of shell morphology tall to broad with intermediate shell shapes (as for example in Fig. 13B from Bauhaus). In addition, the anatomical and radular details of the broad and narrow forms are very similar. Because of this, and the existence of at least some apparent intermediates, we treat both forms as a single species pending more detailed studies. Specimens near the entrance to Damper cave (C.203680) are larger with rather dark­coloured shells than those from further inside the cave.

Pseudotricula conica is most similar to P. arthurclarkei from Quetzalcoatl Conduit but differs in its smaller size (P<0.001) although one lot from close to the entrance of Damper Cave (C.203680) is nearly as large as the former species. P. conica also tends to have less convex whorls and has weak to obsolete opercular ridges. The two taxa are not sympatric.

Figures

FIGURE 3: Radulae of Pseudotricula species. A, B, Pseudotricula eberhardi, C.165053, Black Curtain Streamway, Cueva Blanca; C–H, Pseudotricula expandolabra, C, D, C.201495, Persephone Streamway, Bauhaus, E, G, H, C.201811, Persephone Pot, Bauhaus, F, C.201822, main streamway, Bauhaus; I, Pseudotricula arthurclarkei, C.203671, paratype, Quetzalcoatl Conduit; J–L, Pseudotricula conica, C.203676, paratype, Cane Toad Abuse Streamway, Damper Cave. A, C, G, K, central, lateral inner and outer marginal teeth; B, E, L, central teeth; D, outer marginal teeth; F, J, lateral and inner marginal teeth; H, lateral tooth; I, central and lateral teeth. Scales: A, B, E, H–J, L 10 m; C, F, G, K, 20 m; D, 5 m.

FIGURE 4. Dorsal views of penes of Pseudotricula and Nanocochlea species. A,. Pseudotricula eberhardi; B, Pseudotricula expandolabra; C, Nanocochlea stylesae; D, Nanocochlea damperensis; E, Pseudotricula conica. Scales A, B, E, 0.2 mm; C, D, 0.1 mm. Abbreviations: ds, distal swelling; pd, penial duct.

FIGURE 6. Protoconchs and teleoconch microsculpture of Pseudotricula and Nanocochlea species. A–D, Pseudotricula expandolabra, A, B, D, C.201493, paratype, main streamway, Bauhaus, C, C.201495, Persephone Streamway, Bauhaus; E–G, Pseudotricula conica, E, F, C.201464, Cane Toad Abuse Streamway, Damper Cave, G, Persephone Pot, Bauhaus; Honey and Cream Streamway, Damper Cave; H, Nanocochlea exigua, C.201475; I, J, Nanocochlea stylesae, C.201476, paratypes, Malani Creek; K–M, Nanocochlea damperensis, K, L, C.203685, paratypes, first crossing, Damper Creek, M, C.201282, Near New River Lagoon, E side, Limestone Ck, where tagged track crosses; N, O, Pseudotricula progenitor, C.201821, main streamway, Bauhaus. A, B, E, F, H, K–N, protoconch; C, D, G, I, J, O, microsculpture. Scales: A, C–E, J, K, M, O, 200 m; B, F–I, L, N, 100 m.

FIGURE 7. Opercula of Pseudotricula species. A, B, Pseudotricula expandolabra, C.201493, paratypes, main streamway, Bauhaus; C, Pseudotricula auriforma, C.201496, paratype, main streamway, Damper Cave; D, E, Pseudotricula arthurclarkei, C.203671, paratypes, Quetzalcoatl Conduit; F–I, Pseudotricula conica, F, G, C.203680, main streamway, near entrance, Damper Cave; H, I, C.201459, Screaming Stals streamway, Bauhaus; A, D, F, H, outer side; B, C, E, H, I, inner side; Scales: A–I, 200 m.

FIGURE 8. Pallial cavities of male specimens of Pseudotricula and Nanocochlea species. A, Pseudotricula expandolabra, C.201493, paratype, Persephone Streamway, Bauhaus; B, Pseudotricula arthurclarkei, C.203671, paratype, Quetzalcoatl Conduit; C, Pseudotricula auriforma, C.201496, paratype, main streamway, Damper Cave; D, E, Pseudotricula conica, D, C.203680, main streamway near entrance, Damper Cave, E, Cane Toad Abuse Streamway, Damper Cave; F, Nanocochlea exigua, C.203677, paratype, Cane Toad Abuse Streamway, Damper Cave; G, Nanocochlea damperensis, C.203685, paratype, first crossing, Damper Creek; H, Pseudotricula progenitor, C.201821, main streamway, Bauhaus. Scales: A–D, F–H, 500 m, E, 1 mm. Abbreviations: a, anus; ct, ctenidium; ev, efferent vein; os, osphradium; pc, pericardium; pe, pallial edge; ppw, posterior pallial wall; r, rectum; rg, renal gland. The stippled area represents the hypobranchial gland.

FIGURE 9. Head, penis and stomach of Pseudotricula species. A, D, Pseudotricula conica, C.203680, main streamway near entrance, Damper Cave; C, Pseudotricula expandolabra, C.201493, paratype, Persephone Streamway, Bauhaus; B, E, Pseudotricula progenitor, C.201821, main streamway, Bauhaus. A, B, head and penis; C–E, stomach. Scales: A–E, 500 m. Abbreviations: dgo, opening from stomach to digestive gland; ey, eye; int, intestine; oes, oesophagus, p, penis; pg, penial duck; sn, snout; ss, style sack; st, stomach; tn, tentacle.

FIGURE 10. Female reproductive systems of Pseudotricula species. A ­ C, Pseudotricula expandolabra, A, B, C.201493, paratype, Persephone Streamway, Bauhaus, C, C.201815, Persephone Streamway, Bauhaus; D, Pseudotricula auriforma, C.201496, paratype, main streamway, Damper Cave; E, Pseudotricula arthurclarkei, C.203671, paratype, Quetzalcoatl Conduit; F, G, Pseudotricula conica, F, C203680, main streamway near entrance, Damper Cave, G, Cane Toad Abuse Streamway, Damper Cave. Scale: 500 m. Abbreviations: ag, albumen gland; bc, bursa copulatrix; bd, bursal duct; cg, capsule gland; co, coiled oviduct; po, genital opening; pw, pallial wall; sr, seminal receptacle; vc, ventral channel.

FIGURE 12. Shells of Pseudotricula species. A, Pseudotricula arthurclarkei, holotype, C.439656, Quetzalcoatl Conduit; B ­ D, Pseudotricula conica, B, holotype, Cane Toad Abuse Streamway, Damper Cave; C, C.203680, main streamway near entrance, Damper Cave; D, C.201813, Persephone Pot, Bauhaus. Scales: A–D, 500 m.

FIGURE 13. Shells of Pseudotricula species. A ­ F, Pseudotricula conica, A, C.203694, Black Curtain streamway, Cueva Blanca, B, Screaming Stals streamway, Bauhaus; C, C.201813, Persephone Pot, Bauhaus, D, C.203464, Cane Toad Abuse Streamway, Damper Cave, E, C.201488, main streamway, Damper Cave, F, C.203692, Damper Cave. Scales: 1 mm.