Amplirhagada decora, 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 : 240-242

Amplirhagada decora n.sp.

Type locality ( Fig. 1 ). Western Australia, northwestern Kimberley, Bonaparte Archipelago, Bigge Island , 4.3 km north of Savage Hill , 14°35'15"S 125°11'05"E; KIS 1-41. Vine thicket on lower and mid slopes north of small stream, dolerite, on trees and bushes in wetter sections (leg. V. Kessner, 17 February 2008) .

Type material. Holotype WAM S34609 (Pl. 1.15) . Paratypes AMS C463698 (8 preserved specimens, as holotype), WAM S36873 (17 preserved specimens, as holotype),AMS C463699 (4 preserved specimens, 14°35'13.3"S 125°11'10.5"E) , WAM S36874 (9 preserved specimens, 14°35'13.3"S 125°11'10.5"E) , AMS C463700 (shell, 14°35'15"S 125°11'05"E), WAM S36963 (2 shells, 14°35'15"S 125°11'05"E) .

Additional, non-type material. WAM S36461 –7, WAM S36652 –4, WAM S36872 (Bigge Island).

Etymology. From decora (Latin = elegant, beautiful) in reference to its beautiful shell.

Shell ( Fig. 35A–C , Pl. 1.15). Globose, with medium to high spire; solid. Periphery angulate; upper sector of whorls flattened to rounded; basal sector rounded. Umbilicus completely concealed by columellar reflection. Background colour brownish horn; with well defined, dark brown, moderately broad sub-sutural and mid-whorl bands being most conspicuous on last whorls; ventral colour horn; outer lip colour same as shell; inner lip translucent. Protoconch c. 2 mm in diameter, comprising 1.5 whorls, sculptured by fine, indistinct axial lirae. Teleoconch with fine axial lirae, rounded in cross-section, regularly spaced, spaces equal to thickness of lirae, lirae distributed evenly across shell surface, reduced underneath suture. Angle of aperture 30°, outer lip rounded, sharp to moderately thick, not or slightly expanded, not reflected; basal and palatal node absent. Parietal wall of inner lip absent.

Pallial morphology. Pallial cavity deep, extending one whorl. Mottled pigmentation on mantle dark grey. Kidney extending about half of pallial cavity.

Genital morphology ( Figs. 33–34 ). Penis straight, of more or less same length as anterior pert of oviduct. Vas deferens forms simple loop before entering penis. Penial retractor muscle of about same length as penis. Penial sheath evenly thin. Penial verge tiny (barely visible), with truncated tip. Penial wall pustules of average size, densely arranged in rows over entire length of inner penial wall; partly fused to small elongated ridges. Main stimulatory pilaster well-differentiated, forming a very large cone sculptured by dense ridges comprising apical to median portion of penial chamber; pilaster ridges support little hooks. Vas deferens rather undulated, moderately thick, entering penial sheath in upper third of penis. Vagina short, tubular, posteriorly inflated; inner wall with longitudinal pilasters. Spermathecal duct of medium thickness, internally with smooth longitudinal pilasters. Spermathecal head globular to elongately inflated, connected with oviduct by connective tissue, internally smooth, with thin wall. Free oviduct comprising more than half of anterior part of oviduct, rather straight. Spermoviduct longer than anterior part of oviduct. Talon embedded in albumen gland close to anterior end of albumen gland.

Radular morphology ( Fig. 35E–G ). Rectangular. Tooth formula C+16–18+0–3+20–21. In average 137.3±25.4 rows of teeth, 27.8±2.7 rows of teeth (n = 3). Central teeth with bluntly pointed, triangular to ovate mesocones, shorter than base of tooth; ectocones vestigial. Lateral teeth with bluntly pointed, triangular to ovate mesocones, shorter than base of tooth; ectocones and endocones vestigial. Marginal teeth with broad, flattened mesocones; ectocones shorter and narrower than mesocones, divided into two denticles, endocones reduced in size.

Comparative remarks. Its highly elevated, dome-shaped shell being characteristic (H/D larger than in many other species with more conical shells). Comparatively large, coneshaped main pilaster, rather large pustules of inner penial wall and tiny verge are diagnostic. This species was referred to as “ Amplirhagada sp. 23” by Solem (1991).

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 33. Genitalia of Amplirhagada decora n.sp., paratypeAMS C463699 (17 February, scale 10 mm) (drawing F.K.).Compare with Fig. 3 for labelling of structures.

Figure 34. Interior of penial chamber of Amplirhagada decora n.sp., paratypeAMS C463698 (17 February, scale 5 mm) (drawing F.K.). Compare with Fig. 4 for labelling of structures.

Figure 35. SEM photographs of Amplirhagada decora n.sp. (A–C) Shell, paratype AMS C463700: (A) apical whorl viewed from above (scale 1 mm); (B) sculpture on first three whorls viewed from above (scale 1 mm); (C) sculpture on last whorl (scale 100 µm). (D) Jaw, paratype AMS C463698 (scale 100 µm). (E–G) Radula, paratype AMS C463698: (E) central and lateral teeth (scale 20 µm); (F) close-up of lateral teeth (scale 10 µm); (G) inner and middle marginal teeth (scale 20 µm).