Nanocochlea damperensis, 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 : 47-49

Nanocochlea damperensis n. sp.

Figures 4D ; 6K–M ; 8G ; 14E–G ; 15G–H ; 16D–F ; 17G–K ; 18B .

Type material

Holotype: AMS C.439399, first crossing, Damper Ck, stn PBs­1A, 29 MAR 1994.

Paratypes: AMS C.203685, same data, 20+ dry, 20+ wet ; QVM, 9:20543 (5 wet); AMS C.439400, same data (1 dry figured paratype) .

Other material examined (all AMS)

Damper Creek: C.203673, 10m outside Damper Cave, stn PBs­2A (22 dry, 20+ wet); C.201282, near New River Lagoon, E side, Limestone Ck, where track crosses creek, JW 49, 15 FEB 1988; 20+ dry, 20 wet; figured specimen from same lot, C.343820.

Bauhaus: C.303685, cave entrance.

Etymology Named after Damper Creek.

Description

Shell ( Figs. 6K–M ; 14E–G ; 15G, H ). Length up to 2.3 mm; conical (SW/SL 0.50–0.69, mean 0.61, n = 63); spire moderate to tall, convex in outline; last whorl evenly rounded; suture indented/impressed. Protoconch microsculpture of small shallow pits and pustules. Teleoconch up to 3.3 whorls in adult; umbilicus present only in juveniles; aperture oval to pear­shaped; moderate size, shorter than spire (AL/SL 0.37–0.47, mean 0.42, n = 63); outer lip, orthocline, weakly thickened in adult, straight to slightly convex, without reflection; notch usually present in posterior corner of aperture; outer lip orthocline to weakly opisthocline; inner lip thin and narrow, in partial contact or narrowly separated from parietal wall.

Dimensions. See Table 12.

Operculum ( Fig. 16D–F ). Inner surface with or without white smear and, in some, 3– 5 weak ridges (reduced pegs).

Eyes. Slightly pigmented.

Pallial cavity ( Fig. 8G ). Ctenidium narrow; 12–13 very small filaments; osphradium between posterior end and middle of ctenidium; hypobranchial gland thick to moderately developed; renal organ extends forward ca. ½ into pallial cavity; pericardium more than ½ in pallial roof.

Radula ( Fig. 17G–K ). Central teeth: dorsal edge with moderate to deep indentation; 4–5 lateral cusps, median cusp narrow, sharply pointed, about twice as long as adjacent cusps. Lateral teeth: dorsal edge with shallow indentation; with 5–6 cusps on outer and 4– 6 on inner side; median cusp narrow, sharply pointed, less than, to about twice as long as, adjacent cusps; ratio of cutting edge to shaft about ¼; basal projection pointed. Marginal teeth: Inner with 20–27 cusps; outer with 20–26 cusps.

Stomach. Stomach with posterior chamber a little smaller than anterior chamber.

Male genital system. Testis of 1.0–1.25 whorls; oval to kidney­shaped; oval in section. Pallial vas deferens straight to slightly undulating at prostate; straight between prostate and penis and at base of penis. Penis ( Fig. 4D ) with weak swelling in mid­distal portion; distal end long, papilla­like; medial section parallel sided; of medium length; penial duct in medial section strongly undulating; base of penis moderately wide; with moderate folds; penial duct straight to undulating.

Female genital system ( Fig. 18B ). Ovary of 1.0 whorls; oviduct extends to posterior edge of bursa copulatrix or slightly less; joins bursal duct just in front of posterior pallial wall. Bursa copulatrix of medium size, not extending to posterior pallial wall; globular; with bursal duct arising from middle of anterior edge of bursa; straight. Seminal receptacle at middle of inner wall of bursa copulatrix; ovoid or pyriform. More than ½ of albumen gland in front of posterior pallial wall; capsule gland up to? length of albumen gland; oval to compressed oval in section; anterior end blunt; ventral channel with indistinct to distinct vestibule; genital opening overlapping anterior end of capsule gland.

Distribution and habitat

Found in Damper Creek near the entrance to Damper Cave but was not found in samples from inside Damper Cave (in the same creek). A sample of mainly empty shells from seepages at the entrance of Bauhaus cave ( Fig. 15G, H ) is also attributed to this species and a single dead shell (AMS C. 203714) from inside Bauhaus (Persephone Pot) is presumably washed in from a surface seepage. Specimens from the lower end of Limestone Creek on the eastern side of New River Lagoon are also attributed to this species (see remarks). The site in this creek is approximately 1.7 km S of the lower end of Damper Ck, although about 3.5 km separate the two locations where the samples were collected.

Remarks

Nanocochlea damperensis differs from the other Nanocochlea described to date in its broadly pupiform shell shape. Specimens from Limestone Creek are almost identical to the type material, although have more ctenidial filaments (14–17), 5–6 lateral cusps on the central teeth and the pallial vas deferens undulates rather than being straight. Other anatomical differences are the seminal receptacle is ovoid, not globular, the capsule gland has a terminal opening in some specimens and most specimens lack a distinct white smear on the operculum. Given their close geographic proximity and overall similarity, these two populations are considered to be conspecific pending more detailed investigation.

The very weak (rudimentary) multiple pegs on the operculum of this species resemble those seen in P. conica and P. arthurclarkei and have not been observed in other taxa included in Nanocochlea .

The shell­shape of this species resembles that of some taxa included in Austropyrgus (see Clark et al. 2003). Members of that genus have distinct pegs on the operculum, lack an S­shaped rectum and have three or more basal cusps on the central teeth.

Figures

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 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 14. Shells of Nanocochlea species and Pseudotricula progenitor. A ­ C, Nanocochlea exigua, A, holotype, C.439393, Cane Toad Abuse Streamway, Damper Cave; B, C, C.201465, main streamway, Damper Cave; D, Nanocochlea stylesae, holotype, C.439398, Malani Creek; E–G, Nanocochlea damperensis, E, C.203685, paratype, first crossing, Damper Creek; F, holotype, C.439399, first crossing, Damper Creek, F, C.201282, Near New River Lagoon, E side, Limestone Ck, where tagged track crosses; H, I, Pseudotricula progenitor, H, paratype, C.439397, Persephone Streamway, Bauhaus; I, holotype, C.439396, Persephone Streamway, Bauhaus. Scales: 500 m.

FIGURE 15. Shells of Nanocochlea species and Pseudotricula progenitor. A ­ C, Nanocochlea exigua, A, C.203674, outside Damper Cave, Damper Creek B, C.166855, Persephone Pot, Bauhaus, C, C.201465, main streamway, Damper Cave; D–F, Nanocochlea stylesae, D, C.201476, paratype, Malani Creek, E, F, C.203686, first crossing, Damper Creek; G­I, Nanocochlea damperensis, G,H, C.303685, seepages at Bauhaus entrance, I, C.203685, paratype, first crossing, Damper Creek; J–L, Pseudotricula progenitor, J, L, C.201463, paratype, Persephone streamway, Bauhaus, K, C.201454, Persephone, Bauhaus. Scales: 1 mm.

FIGURE 16. Opercula of Nanocochlea species and Pseudotricula progenitor. A ­ C, Nanocochlea exigua, C.203677, paratypes, Cane Toad Abuse Streamway, Damper Cave; D ­ F, Nanocochlea damperensis; C–E, C.203685, paratypes, first crossing, Damper Creek; F, C.201282, Near New River Lagoon, E side, Limestone Ck, where tagged track crosses; G, H, Pseudotricula progenitor, C.201821, main streamway, Bauhaus; A, D, G, outer side; B, C, E, F, H, inner side; Scales: A, B, D, 200 m, C, E–H, 100 m.

FIGURE 17. Radulae of Nanocochlea species Pseudotricula progenitor. A ­ C, Nanocochlea exigua, A, C.201475, Honey and Cream Streamway, Damper Cave, B, D, C.201465, main streamway, Damper Cave; D– E, Nanocochlea stylesae, C.201476, paratypes, Malani Creek; G–K, Nanocochlea damperensis, G, H, C.203685, paratypes, first crossing, Damper Creek, I–K, C.201282, Near New River Lagoon, E side, Limestone Ck, where tagged track crosses; L–O, Pseudotricula progenitor, C.201821, main streamway, Bauhaus. A, E, central and lateral teeth; B, F, I, M, central, lateral, inner and outer marginal teeth; C, D, J, N central teeth; G, L, lateral teeth; H, central lateral inner and outer marginal teeth; K, outer marginal teeth. Scales: A, G–H, K, L, 10 m; B, I, M, 20 m; C, D, J, N, 5 m.

FIGURE 18. Female reproductive system of Nanocochlea species and Pseudotricula progenitor. A, Nanocochlea exigua, C.203677, paratype, Cane Toad Abuse Streamway, Damper Cave; B, Nanocochlea damperensis, C.203685, paratype, first crossing, Damper Creek; C, D, Pseudotricula progenitor, C.201821, main streamway, Bauhaus. Scales: 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.