Amplirhagada descartesana, Köhler, 2010

Köhler, Frank, 2010, Uncovering Local Endemism in the Kimberley, Western Australia: Description of New Species of the Genus Amplirhagada Iredale, 1933 (Pulmonata: Camaenidae), Records of the Australian Museum 62 (2), pp. 217-284 : 234-236

Amplirhagada descartesana n.sp.

Type locality ( Fig. 1 ). Western Australia, northwestern Kimberley, Admiralty Gulf, Institute Islands , Descartes Island , 14°10'26"S 125°40'38"E; KC-071 (leg. V. Kessner & A. Longbottom, 19 July 1988) .

Type material. Holotype WAM S34607 (Pl. 1.12) . Paratypes WAM S41491 (4 preserved specimens, as holotype) , FMNH 219276 (5 preserved specimens, as holotype) , FMNH 219272 (16 preserved specimens, unnamed island SW of Descartes Island , 14°10'45"S 125°40'00"E, KC/070) , WAM S41490 (10 preserved specimens, same as FMNH 219272 ) , AMS C463749 (7 preserved specimens, same as FMNH 219272 ) .

Additional, non-type material. WAM S41452 ( Descartes Island , 125°40'47"E 14°09'50"S) .

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

Shell ( Fig. 24A–D , Pl. 1.12). Semi-globose to broadly conical with medium high spire; thin (translucent) to solid. Periphery evenly rounded to slightly angulate; upper and basal sectors of whorls rounded. Umbilicus forming a chink to narrowly winding opening, 30–100 percent concealed by columellar reflection. Background colour brownish horn; uniform or banded; if present sub-sutural and mid-whorl bands diffuse, thin, brown, on last whorl(s) only; ventral colour, outer and inner lip colour whitish to cream. Protoconch c. 2.8 mm in diameter with 1.7 whorls, almost smooth, sculptured by faint axial lirae. Teleoconch sculptured by coarse lirae, rounded in cross-section, regularly spaced, spaces equal to thickness of lirae, evenly distributed across shell and whorl diameter even, reduced underneath suture.Angle of aperture 45°, outer lip rounded, moderately thick, slightly expanded, slightly reflected; basal node absent or weak, palatal node absent. Parietal wall of inner lip inconspicuous.

Pallial morphology. Pallial cavity moderately deep, extending 3 ⁄ 4 whorl. Mottled pigmentation on mantle dark grey. Kidney extending about half of pallial cavity.

Genital morphology ( Figs. 25–26 ). Penis straight to slightly curved, longer than anterior part of oviduct. Vas deferens forms simple loop before entering penis. Penial retractor muscle shorter than penis. Penial verge short (<1 ⁄ 4 penial chamber), slender to spatulate, with pointed tip. Penial wall pustules present, of average size, slightly elongated, arranged in rows across entire length of inner penial wall. Main stimulatory pilaster well-differentiated, large, cone-shaped, sculptured by smooth horizontal ridges, comprising entire length of penial chamber. Vas deferens entering penial sheath in upper third. Vagina comparatively short to moderately long, posteriorly inflated. Inner vaginal wall with smooth longitudinal pilasters. Spermathecal duct comparatively wide, internally with smooth longitudinal pilasters. Spermathecal head elongately inflated, connected with oviduct by connective tissue, internally smooth, with delicate wall. Free oviduct comprising about half of anterior part of oviduct, rather straight. Spermoviduct clearly longer than anterior part of oviduct. Talon embedded in albumen gland close to anterior end.

Radular morphology ( Fig. 24E–G ). Rectangular. Tooth formula C+16–17+3–4+18–20. In average with 139±5.5 rows of teeth, 31.4±0.2 rows per mm (n = 2). Central teeth with bluntly pointed, triangular mesocones, shorter than base of tooth; ectocones small. Lateral teeth with bluntly pointed, triangular mesocones, length equal to base of tooth; ectocones small, endocones vestigial. Marginal teeth with elongate mesocones; ectocones shorter and narrower than mesocones, divided into two denticles; endocones smaller than ectocones.

Comparative remarks. The present material has been labelled as “ Amplirhagada sp. 74” by Solem. The species is most readily distinguished from other species from the Montesquieu Islands by its more turreted shell. Similar to A. montesquieuana , its axial sculpture is more regular than that of A. combeana and A. mckenziei . From A. montesquieuana it differs by its larger size and more conical shape. The main stimulatory pilaster is similar to that in A. montesquieuana in shape but lacks “hooked toes”; broader than pilaster in A. ponderi and A. mckenziei ; penial wall pustulation differs markedly from that in A. montesquieuana .

Figures

Figure 1. Distribution of Amplirhagada species in the Kimberley region, northwestern Australia. (1) A. euroa n.sp., Adolphus Island. (2) A. solemiana n.sp., Middle Osborn Island. (3) A. indistincta n.sp., Southwest Osborn Island, Kidney Island. (4) A. combeana, Cassini Island. (5) A. mckenziei n.sp., Oliver Island. (6) A. ponderi n.sp., Kingsmill Island. (7) A. montesquieuana n.sp., Fenelon Island. (8) A. descartesana n.sp., Descartes Island. (9) A. katerana, Katers Island. (10) A. puescheli n.sp., unnamed island near Prudhoe Island. (11) A. decora n.sp., A. kessneri n.sp., Bigge Island. (12) A. berthierana n.sp., Berthier Island. (13) A. lamarckiana n.sp., Lamarck Island.(14) A. anderdonensis n.sp., unnamed island, Anderdon Islands. (15) A. tricenaria n.sp., Prince Frederick Harbour, north of Hunter River mouth. (16) A. regia n.sp., A. boongareensis n.sp., A. gibsoni n.sp., and Amplirhagada sp., Boongaree Island. (17) A. yorkensis n.sp., Coronation Island. (18) A. buffonensis n.sp., Buffon Island. (19) A. uwinsensis n.sp., Uwins Island. (20) A. sphaeroidea n.sp., St. Andrews Island. (21) A. basilica n.sp., and A. camdenensis n.sp., Augustus Island. (22) A. kimberleyana n.sp., NW of Wilson Point. (23) A. gemina n.sp., 1.5 km SE of Hall Point. (24) A. dubitabile n.sp., Steep Island. (25) A. napierana, north Napier ranges. (26) A. percita, Napier ranges. (27) A. castra, A. mitchelliana, and A. varia, Mitchell Plateau.

Figure 24. SEM photographs of Amplirhagada descartesana n.sp., paratype AMS C463749. (A–D) Shell: (A) apical whorl viewed from above (scale 200 µm); (B) sculpture on first four whorls viewed from above (scale 1 mm); (C) sculpture, lateral view (scale 100 µm); (D) close-up of sculpture, obliquely from above (scale 100 µm). (E–G) Radula: (E) central and lateral teeth (Scale 20 µm); (F) close-up of central and inner lateral teeth (scale 10 µm); (G) outer lateral and inner marginal teeth (scale 10 µm). (H) Jaw (scale 100 µm).

Figure 25. Genitalia of Amplirhagada descartesana n.sp., paratype WAM S41491 (20 July, scale 10 mm). Compare with Fig. 3 for labelling of structures.

Figure 26. Interior of penial chamber of Amplirhagada descartesana n.sp., paratype FMNH 219276 (20 July, scale 5 mm). Compare with Fig. 4 for labelling of structures.