Coliracemata clarkae, 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 : 137-139

Coliracemata clarkae n. sp.

Figures 16 , 25 , 26

Etymology. Named after Dr Stephanie Clark, the collector of the type material.

Types and type localities. Holotype: Central Lakes, Townsville, Queensland, Australia, along edges, under palm fronds and amongst mussels, 19°16'01" S, 146°49'01" E, May 1992. Coll. S.A. Clark (AMS C.462962). Paratypes: Same data (AMS C.378422, 4 spms).

Material examined. Type material.

Distribution. Known only from Townsville, Queensland, but is probably more widespread in tropical Queensland.

Description. Shell. Minute (up to 1.7 mm in maximum diameter; Table 3), spire low ( Fig. 16 G–I). Protoconch not elevated above line of spire, details not clearly discernable in available material but approximately of 1.5 whorls; first half whorl has 4 spiral ridges, remainder apparently smooth. Teleoconch of approximately 1.5 convex whorls, whole surface sculptured with fine, simple spiral lirae with very fine, close axial threads in the interspaces which are about 1–2 times width of spirals. Periphery evenly convex. Base evenly convex, umbilicus moderately wide (slightly less than half width of base), spiral sculpture continuous within. Sutures impressed. Aperture near circular, with simple, slightly thickened peristome, no external varix. Colour varies from white to dark orange-red or dark brown (colour imparted by deposits on shell surface).

Operculum. Horny, near circular, of 5–6 slowly increasing whorls. Interior with narrow, raised edge to muscle attachment area close to thickened, ridge-like columellar edge. Small projection in middle part. White, possibly calcareous, smear on middle of inner surface present.

Head-foot. Cephalic tentacles parallel-sided, moderately long, with distinct compound cilia distally and narrow black band at about distal third to quarter, otherwise colourless with tiny white spots. Actively beating cilia over most of tentacle surface. Foot mostly unpigmented; anterior end with shallow notch, laterally extended, with grey spot in middle of each antero-lateral lobe; posteriorly foot tapering to point. Anterior pedal mucous gland with antero-lateral extensions and concentrated into short medial gland. Snout moderately long, weakly bilobed distally, grey to black laterally, dorsally whitish with pink buccal mass showing through.

Ctenidium . About 20 filaments.

Radula . Typical of family. Cusp formulae 4+1+4, 5+1+4, 19–20,?17, median cusps of central and lateral teeth long (about twice as long as adjacent cusps), narrow, pointed; other cusps on all teeth slender, pointed.

Gut. Anterior oesophagus with two folds; rectum with two tight loops as in Co. mortoni .

Penis. Short, wide distally and proximally ( Fig. 25 A, B). Five, equally-sized distinct clusters of many small apocrine glands on dorsal edge of middle portion. Tip narrow, with short, pointed papilla. Penial duct not observed.

Oviduct. Albumen gland shorter than capsule gland ( Fig. 25 C, D). Coiled oviduct narrow, with simple, open coil. Seminal receptacles short, about equal in size. Ventral channel narrow, rather long, nearly straight. Bursa small, lying on left side of oviduct gland, about 1/3 behind posterior wall of mantle cavity; posterior part slightly wider than anterior; extremely short bursal duct on left side of capsule gland. Genital opening simple, slightly posterior to anterior end of capsule gland.

Nervous system. Similar to that of Cl. bicingulata , but pleural-supraoesophageal connective slightly shorter than the latter.

Remarks. This species is one of the smallest clenchiellids and is, at least superficially, the most similar in shell features to Coliracemata ? microscopica but differs, as far as can be judged from the description and figure of that species, in its somewhat smaller size (~1.3 vs 1.5 mm in maximum diameter). In the absence of suitable material from India, a more detailed comparison is not possible. It has finer sculpture, a narrower umbilicus and a more elevated spire than the other two species of Coliracemata recognised here.

At the type locality, and, possibly in some other north Queensland localities, Co. clarkae lives sympatrically with Cl. minutissima which is much more abundant in the type locality (see Fig. 26 for type localities of clenchiellids other than species of Clenchiella ). The two species can be readily separated on animal pigmentation and penial morphology, as well as on shell morphology, particularly the possession of a varix in the latter species. Co. clarkae differs from the other two congeners described herein in having a higher spire and narrower umbilicus, as well as in details of the reproductive anatomy.

Figures

FIGURE 16. Holotypes of new species of Coliracemata n. gen. (from left towards right: dorsal, lateral and ventral view respectively). A – C, Coliracemata mortoni n. sp. (AMS C. 269811; shell diameter 1.82 mm); D – F, Coliracemata katurana n. sp. (AMS C. 445414; shell diameter 1.06 mm); G – I, Coliracemata clarkae n. sp. (AMS C. 462962; shell diameter 1.36 mm).

FIGURE 25. Reproductive anatomy of Coliracemata clarkae (AMS C. 378422). 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). Scale bars: 200 µm. Abbreviations: ag, albumen gland; bc, bursa copulatrix; cag, clusters of apocrine glands; cb, cut base of penis; cg, capsule gland; co, coiled oviduct; fa, female aperture; ppw, position of posterior wall of mantle cavity; sr, seminal receptacle.

FIGURE 26. Type localities of all species of Coliracemata n. gen., Colenuda n. gen., and Coleglabra n. gen.