Amplirhagada indistincta, 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 : 225-227

Amplirhagada indistincta n.sp.

Type locality ( Fig. 1 ). Western Australia, northwestern Kimberley, Bonaparte Archipelago, Admiralty Gulf , West coast of South West Osborn Island , 14°22'26"S 125°56'13"E; KIS 3-7. Isolated vine thicket patch on dune behind sand beach, on trees, under logs (leg. V. Kessner, 29 July 2007) .

Type material. Holotype WAM S34603 (Pl. 1.5) . Paratypes AMS C463686 (5 preserved specimens, as holotype), WAM S36617 (10 preserved specimens, as holotype), AMS C463688 (5 shells, 14°22'26"S 125°56'13"E) , WAM S36575 (15 shells, 14°22'26"S 125°56'13"E) , AMS C463687 (20 preserved specimens, 14°22'26.5"S 125°56'17.8"E), WAM S36865 (40 preserved specimens, 14°22'26.5"S 125°56'17.8"E) , AMS C463689 (11 shells, east coast, 14°22'47.3"S 125°56'00.6"E), WAM S36962 (25 shells, east coast, 14°22'47.3"S 125°56'00.6"E) .

Additional, non-type material. WAM S28521 , WAM S36491 –501 , WAM S36574 , WAM S36577 , WAM S36612 –16 , WAM S36618–25 , WAM S36863 –4 , WAM S36866 , AMS C463690–1 ( South West Osborn Island ) ; WAM S41454 , AMS C463724 ( Kidney Island ; 14.329°S 125.985°E) .

Etymology. From indistincta (Latin = indistinct) referring to the close morphological resemblance with A. solemiana .

Sealing strategy. Rock sealer.

Shell ( Fig. 11A–D , Pl. 1.5–6). Semi-globose to broadly conical with moderate to high spire; solid to thick, not translucent. Periphery well rounded to slightly angulate. Umbilicus completely concealed by columellar reflection. Background colour yellowish to brownish white; with thin to moderately broad brown to yellowish brown sub-sutural and mid-whorls bands that are visible on most whorls, subsutural band diffuse, mid-whorl band well marked; ventral colour whitish to greyish white; outer lip colour differs from shell, whitish; inner lip translucent, white. Protoconch c. 2 mm in diameter, comprising about 1.5 whorls, with strong axial sculpture. Teleoconch sculptured by coarse, regular, curved, in cross-section rounded lirae; sculpture evenly distributed across shell and whorl diameter; spaces between lirae equal to thickness of lirae, height of lirae reduced underneath suture. Angle of aperture 30°; outer lip rounded, sharp to moderately thick, expanded, slightly reflected; basal node of lip weak, palatal node absent. Parietal wall of inner lip inconspicuous.

Pallial morphology. Pallial cavity deep, extending one whorl. Pigmentation on mantle consists of sparsely distributed dark brown to black spots. Kidney extending more than half of pallial cavity.

Genital morphology ( Figs. 9–10 ). Penis straight to slightly curved; same length as anterior part of oviduct or slightly longer. Vas deferens forms simple loop before entering penis. Penial retractor muscle about as long as penis. Penial verge long to very long (c. 1 ⁄ 3 to ½ of penial chamber), slender to spatulate with pointed tip. Pustulation comprising entire length of inner penial wall; penial wall pustules small to moderate in size, densely arranged in rows, some of which form four to five longitudinal pilasters along entire length of penial chamber; main stimulatory pilaster not differentiated. Vas deferens entering penial sheath apically. Vagina of medium length, tubular or posteriorly inflated. Inner vaginal wall densely ciliated, ciliae arranged to form smooth longitudinal pilasters, pilasters may be weakly developed. Spermathecal duct of medium thickness; internally with smooth longitudinal pilasters. Spermathecal head elongately inflated, connected with oviduct by connective tissue; inside entirely smooth; wall moderately thick. Length of free oviduct equivalent to about half of anterior part of oviduct; coiled underneath entrance to spermoviduct. Spermoviduct longer than anterior part of oviduct. Talon embedded in albumen gland close to anterior end.

Radular morphology ( Fig. 11F–G ). Rectangular. Tooth formula C+12+3–4+20–21. Average number of rows of teeth 126±14 with 26.3±1.5 rows per mm (n = 2). Central teeth with bluntly pointed, ovate mesocones, shorter than base of tooth; ectocones vestigial. Lateral teeth with bluntly pointed, ovate mesocones, shorter than base of tooth; ectocones small, endocones absent. Marginal teeth multicuspic; ectocones shorter and narrower than mesocones, split into two denticles; endocones of approximately same size as ectocones.

Comparative remarks. Most similar to A. solemiana in shell and genital anatomy. Shells of A. indistincta are larger than those of A. solemiana ( Table 1); a one-way ANOVA revealed that both species differ significantly in the shell parameters H, D, and H/D ( Fig. 8 ). Specimens from Kidney Island, which is located in between Middle and Southwest Osborn Island, tend to have slightly larger and more robust shells than specimens from the type locality. In the molecular phylogeny they cluster closely together with A. indistincta and are therefore considered conspecific because their anatomy corresponds with the specimens from Southwest Osborn Island. Amplirhagada solemiana and A. indistincta exhibit a virtually identical genital anatomy but cluster as clearly distinct lineages in the mitochondrial phylogeny (see below). For relationship with A. imitata see under A. solemiana .

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 8. Comparison of A. solemiana and A. indistincta by means of shell parameters. Scatter-plot showing the ratio of shell height (H) versus diameter (D).

Figure 9. Genitalia of Amplirhagada indistincta n.sp., paratype AMS C463687 (11 February, scale 10 mm). Compare with Fig. 3 for labelling of structures.

Figure 10. Interior of penial chamber of Amplirhagada indistincta n.sp., paratypeAMS C463687 (11 February, scale 5 mm). Compare with Fig. 4 for labelling of structures.

Figure 11. SEM photographs of Amplirhagada indistincta n.sp. (A–D) Shell:(A) apical whorl viewed from above, paratypeAMS C463688 (scale 200 µm); (B) first four whorls viewed from above, paratype AMS C463689 (scale 1 mm); (C) details of axial sculpture on last whorl, lateral view, paratypeAMS C463689 (scale 1 mm); (D) close-up of sculpture on last whorl, paratype AMS C463689 (scale 100 µm); (E) jaw, paratypeAMS C463687 (scale 100 µm). (F–G) Radula, paratype AMS C463687: (F) rows of central and lateral teeth (Scale 20 µm); (G) outer lateral and inner marginal teeth (scale 10 µm).