Amplirhagada lamarckiana Köhler 2010, n.sp.

Amplirhagada lamarckiana n.sp.

Type locality (Fig. 1). Western Australia, Kimberley, Bonaparte Archipelago, York Sound, Lamarck Island, 14°46'50"S 125°1'23"E; KC-042 (leg. V. Kessner & A. Longbottom, 14 July 1988).

Type material. Holotype WAM S34612 (Pl. 1.18). Paratypes AMS C463755 (5 preserved specimens), FMNH 219163 (15 preserved specimens), WAM S41485 (8 preserved specimens).

Etymology. In reference to Lamarck Island, where this species occurs.

Shell (Fig. 42A–C, Pl. 1.18). Semi-globose to broadly conical, with medium high spire; thin (translucent). Periphery evenly rounded to slightly angulate; upper sector of whorls rather flattened, basal sector rounded. Umbilicus forming a chink, 90–100 percent concealed by columellar reflection. Background colour light brownish horn, banded. Sub-sutural and mid-whorl bands diffuse to well defined, light brown, thin, visible on last whorl(s) only; ventral colour horn; outer lip colour same as shell; inner lip translucent. Protoconch c. 3 mm in diameter, comprising 1.7 whorls, with fine and indistinct lirae. Teleoconch with rather strong axial growth lines. Angle of aperture 45°; outer lip rounded, sharp to moderately thick, slightly expanded, reflected, basal node of lip absent or weak; palatal node absent. Parietal wall of inner lip absent or inconspicuous.

Pallial morphology. Pallial cavity deep, extending 3 ⁄ 4 whorl. Pigmentation on mantle mottled, black. Kidney extending more than half of pallial cavity.

Genital morphology (Figs. 43–44). Penis straight to curved, of about same length as anterior part of oviduct. Vas deferens coils before entering penis. Penial retractor muscle shorter than penis. Penial sheath delicate. Penial verge tiny (barely visible), slender to spatulate, with pointed tip. Penial wall small, arranged in rows over entire length of inner penial wall. Main stimulatory pilaster elongated, sculptured by horizontal ridges that support little hooks, comprising apical to median portion of penial chamber. Two to three additional pilasters are covered by undifferentiated pustules. Vas deferens entering penial sheath half way up. Vagina moderate, posteriorly inflated; inner vaginal wall with smooth longitudinal pilasters. Spermathecal duct moderately thick, internally with smooth longitudinal pilasters. Spermathecal head globular, connected with oviduct by connective tissue, internally smooth, with delicate wall. Free oviduct comprises more or less half of anterior part of oviduct, straight. Spermoviduct longer than anterior part of oviduct. Talon embedded in albumen gland at junction with spermoviduct.

Radular morphology (Fig. 42E–F). Rectangular. Tooth formula C+14+4+18. With 157 rows of teeth, 27.9 rows per mm (n = 1). Central teeth with bluntly pointed, triangular to ovate mesocones, shorter than base of tooth; ectocones vestigial. Lateral teeth with sharply pointed, triangular mesocones, length equal to base of tooth; ectocones and endocones vestigial. Marginal teeth with triangular mesocones; ectocones shorter and narrower than mesocones, occasionally divided into two denticles, endocones reduced in size.

Comparative remarks. Pustulation of inner penial wall somewhat similar to A. indistincta and A. solemiana, which lack a well-differentiated main pilaster and differ by more conical shape of shell. Main pilaster differs in shape and surface pattern from the two species from Bigge Island. Material of the present species has been labelled as “ Amplirhagada sp. 68” by Solem.