Westracystis Iredale, 1939

Hyman, Isabel T. & Ponder, Winston F., 2010, A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family 2462, Zootaxa 2462 (1), pp. 1-148 : 68-70

Westracystis Iredale, 1939

Westracystis Iredale, 1933: 56 [nom. nud.].

Westracystis Iredale, 1939: 44 . Type species Lamprocystis lissa Smith, 1894 (OD).

Description. External morphology: Shell 4.5–5.1 whorls, glossy, spire and apex slightly raised. Protoconch sculptured with incised spiral grooves; teleoconch with microscopic spiral grooves. Whorl profile rounded above and below evenly convex periphery. Internal walls of early whorls complete; umbilicus open, narrow U-shape. Mantle laps small, narrow, finger-shaped, left lap slightly smaller than right, not fused, uniform in colour. Right mantle lobe of medium size, left and median lobes small, none fused. Sole of foot and caudal apparatus as for family; caudal horn small; caudal foss vertical slit in tail.

Mantle cavity: As for family. Mantle with few visible minor blood vessels, pigmentation absent.

Digestive system: Oesophageal crop absent.

Genital system: As for family. Free oviduct long; capsular gland present; internal longitudinal pilasters present. Bursa copulatrix inserted on vagina, short, less than half spermoviduct length; duct of bursa copulatrix narrow, distinguishable from bursa copulatrix, internally smooth. Vagina very short; internally smooth. Epiphallus enters penis through simple pore; penis internally covered in transverse ( Westracystis lissus ) or longitudinal ( W. fredaslini ) ridges, longitudinal penis pilasters present, penial diverticulum absent. Penial sheath present, very thick ( W. lissus ) to thin ( W. fredaslini ), enclosing only penis; penis retractor muscle attached to base of epiphallic caecum. Epiphallus moderately long ( W. lissus ) to short ( W. fredaslini ); internally with longitudinal pilasters. Epiphallic retractor caecum moderate in size, positioned in middle of epiphallus ( W. lissus ) or towards the penis ( W. fredaslini ). Flagellum present; flagellum and distal part of epiphallus without internal cryptae and externally smooth and slender. Spermatophore not present in dissected material.

Radula: Relatively long and narrow. Central tooth with small ectocones; mesocone lanceolate, longer than tooth base. Lateral and marginal tooth fields distinguishable. Lateral teeth with endocone much smaller than central tooth ectocones; ectocone equal in size to those on central tooth; mesocone longer than tooth base. Marginal teeth with endocones absent; ectocones reduced to a small stub ( W. lissus ) or moderately small ( W. fredaslini ); not subdivided into extra teeth.

Remarks. Westracystis was introduced by Iredale (1933, 1939) for Lamprocystis lissa Smith, 1894 , a Western Australian species that had been previously included in genera Lamprocystis Pfeffer, 1883 ( Cox 1909; Smith 1894) and Microcystis ( Hedley 1916) (both genera belonging to Euconulidae , subfamily Microcystinae ). A second species, Westracystis tentus Iredale, 1939 was later added ( Iredale 1939). Solem (1982) carried out a detailed anatomical study of the genus, synonymising W. tentus with W. lissus and describing a new species, Westracystis fredaslini Solem, 1982 . Solem also confirmed that the genus belonged to Helicarionidae rather than Microcystinae ( Solem 1982, 1988). Two species, W. lissus and W. fredaslini , are accepted by Smith (1992).

Only Westracystis lissus is included in this study; however, the generic description includes details of W. fredaslini from Solem (1982).