Clenchiella Abbott, 1948

Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014, A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea), Zootaxa 3872 (2), pp. 101-153 : 111

Clenchiella Abbott, 1948

Clenchiella Abbott, 1948: 76 .

Type species: Clenchiella victoriae Abbott, 1948 , original designation.

Diagnosis. Shell large for family (1.2–2.3 mm in maximum diameter, although Abbott incorrectly gives up to 4 mm for type species). Spire flat, umbilicus wide. Whorls typically with strong spiral mid-dorsal and mid-ventral keel and many distinct spiral cords ( Fig. 1 ), keels subobsolete to absent in one species ( Fig. 2 ). Aperture near circular, peristome simple, prosocline, external varix heavy, wide. Operculum near circular, thin, horny, of several whorls, nucleus near central; inner side lacks calcareous smear and has central projection (distinct peg to weak nipple-like protrusion). Head-foot usually with black pigment on cephalic tentacles and snout; posterior end of foot pointed. Radula as for family, cusps on inner outer marginal teeth slightly larger than those on outer marginals. Penis with two to four large, simple (i.e. with no apocrine glands) swellings on distal portion. Bursa copulatrix small to extremely large; bursal duct straight or strongly curved. Two posterior seminal receptacles.

Remarks. Clenchiella is distinguished from the other three genera introduced below in having the following combination of characters: dorsal and ventral prominent to weak keels on the shell (absent in one species), a strong external apertural varix, a pigment band on each cephalic tentacle and the penis has a few distinct distal lobes.

Figures

FIGURE 1. Holotypes of species of Clenchiella with distinct keels (from left towards right: dorsal, lateral and ventral view respectively). A – C, Clenchiella victoriae (USNM 488534; shell diameter 2.1 mm); D – F, Clenchiella bicingulata n. sp. (AMS C. 462959; shell diameter 1.97 mm); G – I, Clenchiella varicosa n. sp. (AMS C. 460738; shell diameter 1.96 mm); J – L, Clenchiella iriomotensis n. sp. (AMS C. 445413; shell diameter 1.94 mm).

FIGURE 2. Type specimens of Clenchiella minutissima (from left towards right: dorsal, lateral and ventral view respectively). A – C, holotype of Clenchiella papuensis, synonymised with Clenchiella minutissima herein (NHML, registration number not known; shell diameter 1.69 mm); D – F, syntype of Clenchiella minutissima (MNHNP; shell diameter 1.70 mm).