Coleglabra nordaustralis, Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014

Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014, A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea), Zootaxa 3872 (2), pp. 101-153 : 146-147

Coleglabra nordaustralis n. sp.

Figures 28–32

Etymology. Refers to northern Australia, the provenance of the species.

Types and type locality. Holotype: Douglas-Daly Research Farm, Top End, Douglas River, approx. 1 km E from the junction with Daly River, Northern Territory, Australia. Permanent freshwater river above tidal influence on limestone bed, 13° 50' 15" S, 131° 08' 45" E, 13 Aug. 1995. Coll. V. Kessner (NTM P.53502); Paratypes. Same data (AMS C.307276, 14 spms; C.307290, 20+ spms; C.410981, 7 spms; NTM P.53503, 5 spms).

Material examined. Type material.

Distribution. Known only from the type locality, but may occur in similar conditions in the lower reaches of other coastal rivers in the Northern Territory.

Description. Shell. Minute (up to 1.9 mm in maximum diameter; Table 3), spire slightly raised ( Figs 28 D–F and 29F–K). Protoconch of about 1.2 whorls, surface of protoconch I smooth except for very minute, close-set pustules, terminated by thin, indistinct varix at about 0.9 whorls; protoconch II about quarter whorl, smooth, weakly differentiated from teleoconch. Teleoconch of about 1.7–1.8 convex whorls, upper surface sculptured with few distinct, spiral threads from mid-dorsal to outer part of whorls, interspaces linear to subequal, about 9–11 at end of penultimate whorl, usually subobsolete on last third of last whorl; inner dorsal part of whorls sometimes with few similar spirals or lacks them; often stronger, irregularly spaced commarginal growth lines intersect spirals. Periphery evenly convex, spiral lirae weak to absent on peripheral area. Base evenly convex, umbilicus wide (approximately half width of base), spiral sculpture continuous to subobsolete within. Sutures impressed. Aperture near circular, with simple, slightly thickened peristome, no external varix. Coloration of periostracum variable, including dark grey to black, reddish brown, to yellowish white.

Operculum. Horny, near circular, of about 4 slowly increasing whorls ( Fig. 30 C, D). Interior with simple muscle attachment area. Central part slightly thickened, no projection or white deposit.

Head-foot. Not observed alive. In preserved materials, with long cephalic tentacles and wide snout; pigment lacking on head-foot.

Ctenidium . 16 to 20 filaments.

Radula . Typical of family. Cusp formulae 5+1+5, 4–6+1+5–6, 19–20, approx. 16, median cusps of central and lateral teeth long (nearly twice as long as adjacent cusps), narrow, pointed on central teeth, pointed to blunt on lateral teeth; other cusps on all teeth slender, pointed ( Fig. 31 C, D).

Gut. Anterior oesophagus with two weak folds; rectum with two tight loops.

Penis. Long, slender, tapering, with no distinct swellings or glands; arising from right side of head behind right eye. Tip pointed, with no distinct papilla. Penial duct irregularly undulating ( Fig. 32 E).

Testis and ovary typical of family (i.e., similar to that figured for Clenchiella bicingulata ) ( Fig. 32 F).

Oviduct. Elongate bean-shaped. Albumen gland about as long as capsule gland ( Fig. 32 G, H). Coiled oviduct narrow, with two extremely large coils. Seminal receptacle single, rather long, slender. Ventral channel long, gently curved. Bursa large, about 1/2 behind posterior wall of mantle cavity; posterior end pointed; middle part widest, then narrows anteriorly to open to bursal duct. Bursal duct extremely wide, highly muscular, forming large, round chamber at anterior part (visible from both dorsal and ventral side) of capsule gland. Genital opening simple, on ventral edge of meeting point of ventral channel and bursal duct. Single, slender, posteriorly located seminal receptacle.

Nervous system. Similar to that of Cl. bicingulata .

Remarks. This species is distinguished from other clenchiellids above and with the possible congener below.

Figures

FIGURE 28. Holotypes of Colenuda n. gen. and Coleglabra n. gen. (from left towards right: dorsal, lateral and ventral view respectively). A – C, Colenuda kessneri n. sp. (NTM P. 53500; shell diameter 1.79 mm); D – F, Coleglabra nordaustralis n. sp. (NTM P. 53502; shell diameter 1.82 mm); G – I, Coleglabra sentaniensis (ZMA 1206; shell diameter 1.1 mm).

FIGURE 29. Shell characters of Colenuda kessneri (NTM P. 6529; A – E) and Coleglabra nordaustralis (AMS C. 307276; F – K). Colenuda kessneri: A – C, from left towards right: dorsal, lateral and ventral view respectively; D, protoconch; E, dorsal sculptural detail. Coleglabra nordaustralis: F, dorsal sculptural detail; G, protoconch; H, dorsal view; I, J, lateral view; K, ventral view.

FIGURE 30. External and internal view (left to right) of opercula of: A, B, Colenuda kessneri (NTM P. 6529); C, D, Coleglabra nordaustralis (AMS, C. 307276). Scale bars: 200 µm.

FIGURE 31. Radulae of Colenuda kessneri (NTM P. 6529) and Coleglabra nordaustralis (AMS C. 307276). Colenuda kessneri: A, central, lateral and marginal teeth; B, central and lateral teeth. Coleglabra nordaustralis: C, central, lateral and marginal teeth; D, central and lateral teeth.

FIGURE 32. Reproductive anatomy of Colenuda kessneri (NTM P. 6529; A – D) and Coleglabra nordaustralis (AMS C. 307276; E – H). Colenuda kessneri: A, head with penis, dorsal view; B, penis, ventral view; C, female reproductive system shown from anterior (left) to posterior (right); D, female reproductive system shown from posterior (left) to anterior (right). Coleglabra nordaustralis: E, head with penis, dorso-lateral view; F, ovary; G, female reproductive system shown from anterior (left) to posterior (right); H, female reproductive system shown from posterior (left) to anterior (right). Scale bars: 500 µm. Abbreviations: ag, albumen gland; bc, bursa copulatrix; cb, cut base of penis; cg, capsule gland; co, coiled oviduct; lo, lobe; oo, oocyte; pd, penial duct; pp, penial papilla; ppw, position of posterior wall of mantle cavity; sr, seminal receptacle; uo, upper oviduct; v, vestibule.