Coliracemata mortoni Ponder, Fukuda & Hallan, 2014, n. sp.
Creators: name: Ponder, Winston F.
name: Fukuda, Hiroshi
name: Hallan, Anders
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Clenchiellidae
Coliracemata
Coliracemata mortoni

description: Coliracemata mortoni n. sp.
Figures 16–22, 26
Etymology. Named for Professor Brian Morton as a small recognition of his enormous contributions to marine biological and malacological studies on the Hong Kong marine fauna.
Types and type locality. Holotype: Under wood, front edge of mangrove. Mong Tseng Wai, Southern Deep Bay, Hong Kong. 22˚29’ N, 114˚00’E, 16 Apr. 1983. Coll. W. F. Ponder (AMS C.269811). Paratypes: Same data (AMS C.460381, 5 spms).
Material examined. Type material.
Hong Kong: Same data as type material (AMS C.460380, 20+ spms); Tsim Bei Tsui near Lau Fau Shan, seaward edge in mangroves, 22° 28' N, 113° 59' E, 15 Apr. 1992. Coll. W.F. Ponder (AMS C.463401, 2 spms); Tsim Bei Tsui, Deep Bay, mangroves, 22° 28' N, 113° 59' E, 15 Apr. 1983. Coll. W.F. Ponder (AMS C.463405, 3 spms).
Distribution. Known only from Hong Kong, but is presumably more widespread in southern China.
Description. Shell. Minute (up to 1.9 mm in maximum diameter; Table 3), spire flat (Figs 16 A–C and 17A–C). Protoconch depressed to slightly elevated above spire, about 1.7 whorls, surface of protoconch I sculptured with about three well-spaced very fine spiral threads, terminated by weak varix; protoconch II of one whorl, smooth, terminated by weak varix. Teleoconch of about 1.6 convex whorls, sculptured with distinct, minutely wavy spiral lirae in middle of dorsal part of shell, inner third of dorsal whorls lacking distinct spirals, interspaces about twice width of lirae, about 4–5 lirae and a few finer spiral threads on outer side of whorl at end of penultimate whorl; finer, close-spaced commarginal growth lines intersect spirals, resulting in netted appearance where stronger spirals occur. Periphery evenly convex, spiral weak to subobsolete on peripheral area. Base evenly convex, with wavy spiral lirae, umbilicus wide (nearly half width of base), distinct spiral sculpture lacking in umbilicus. Sutures deeply impressed. Aperture near circular, with simple, slightly thickened peristome, external varix absent. Colour yellow-brown to dark brown due to periostracum and deposits; shell white.
Operculum. Horny, near circular, of 4–5 slowly increasing whorls, each sculptured externally with fine, oblique wrinkles (Fig. 18 A, B). Interior with narrow, raised edge to muscle attachment area close to weakly thickened columellar edge. Small white (calcareous?) sub-spiral projection in middle part, with thickened ridge between projection and outer edge of muscle scar.
Head-foot. Similar to that of Coliracemata clarkae but unpigmented except for dense-white spots on head and a few on basal half of tentacles and foot. Posterior end of foot tapering and rounded posteriorly (Figs 19 and 20).
Ctenidium. About 20 filaments.
Radula. Typical of family. Cusp formulae variable on central and lateral teeth; 2–5+1+2–5, 1–2+1+1–4, 14–17, 12–14, median cusps of central and lateral teeth long (about twice as long [or slightly more] as adjacent cusps), narrow, pointed; other cusps on all teeth slender, pointed (Fig. 21 A, B).
Gut. Anterior oesophagus with two very strong folds; rectum with two tight loops (Fig. 19 C, D).
Penis. Short, wide distally and proximally (Figs 20 and 22). Five to six distinct clusters of many small, apocrine glands on dorsal edge of middle portion; proximal clusters large, distal ones close to tip small. Tip narrow to wide, blunt, with no distinct papilla. Penial duct slightly undulating.
Oviduct. Albumen gland slightly shorter than capsule gland (Fig. 22 D, E). Coiled oviduct narrow, with single S-shaped coil with indentations. Seminal receptacles short, about equal in size. Ventral channel gently curved. Bursa small, slender, lying on left side of oviduct gland, about 1/5 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, on anterior end of bursal duct.
Nervous system. Similar to that of Coliracemata clarkae.
Remarks. This species has a similar umbilicus and probably a lower spire than Coliracemata? microscopica (see below) and is also similar to Co. katurana in shell characters but is much larger. Co. mortoni differs from Co. clarkae in being larger, having more prominent spiral sculpture and a lower spire. The only other similar species found in the same general vicinity is Cl. minutissima, which differs most obviously in having a strong apertural varix. Anatomically it differs from the two congeneric species described herein in details of penial, and female genital tract morphology.
This species may possibly have been combined as part of Tong’s (1986) ‘ Clenchiella sp.’ although she figured and described Clenchiella varicosa n. sp. (see above).
description: Published as part of Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014, A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea), pp. 101-153 in Zootaxa 3872 (2) on pages 130-134, DOI: 10.11646/zootaxa.3872.2.1, http://zenodo.org/record/253224