Amplirhagada solemiana, 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 : 222-224

Amplirhagada solemiana n.sp.

Type locality ( Fig. 1 ). Western Australia, northwestern Kimberley, Bonaparte Archipelago, Admiralty Gulf , west coast of Middle Osborn Island , 14°18'18"S 125°59'35"E; KIS 2–030. Small vine thicket at base of hill, west facing slopes. Common on trees and bushes (leg. V. Kessner, 13 February 2008) .

Type material. Holotype WAM S34602 (Pl. 1.3) . Paratypes AMS C463681 (8 preserved specimens, as holotype), WAM S36860 (20 preserved specimens, as holotype),AMS C463683 (4 shells, 14°18'37.4"S 125°59'18.4"E) , WAM S36572 (10 shells, 14°18'37.4"S 125°59'18.4"E) , AMS C463682 (2 preserved specimens, east coast, 14°18'53.5"S 126°02'06.7"E), WAM S36859 (6 preserved specimens, east coast, 14°18'53.5"S 126°02'06.7"E) .

Additional, non-type material. WAM S36471 , WAM S36566 –71, WAM S36573 , WAM S36585 –99, WAM S36858 , WAM S36861 , WAM S36971 , AMS C463684–5 (Middle Osborn Island).

Etymology. Named in honour of Alan Solem, in recognition of his achievements in camaenid systematics.

Sealing strategy. Rock sealer.

Shell ( Fig. 5A–E, Pl. 1.3–4). Semi-globose with moderately high spire. Thin to solid, translucent. Periphery evenly rounded to slightly angulate; upper and basal sectors of whorls well rounded. Umbilicus open, forming a chink, to 80–90 percent concealed by columellar reflection. Background colour horn to yellowish brown, with brown, well defined to diffuse, moderately broad, sub-sutural and mid-whorl bands, visible on entire shell; ventral and outer lip colour horn; inner lip translucent, pale. Protoconch c. 1.8 mm in diameter, comprising about 1.5 whorls, sculptured by comparatively strong axial ribs. Teleoconch sculptured by coarse, regular lirae, rounded in cross-section; spaces equal to thickness of lirae; sculpture evenly distributed across whorls of shell and across whorl diameter, height of lirae reduced underneath suture. Angle of aperture 45°; outer lip sharp to moderately thick, rounded, slightly expanded, slightly reflected; basal and palatal node absent. Parietal wall of inner lip inconspicuous.

Pallial morphology. Pallial cavity deep, extending one whorl. Pigmentation on mantle consists of sparsely spaced dark grey-black spots. Kidney extending about half of pallial cavity or slightly more.

Genital morphology ( Figs. 6–7 ). 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; pustules small to moderate in size, densely arranged in rows, some of which form four to five corrugated 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. 5F–I). Rectangular. Tooth formula C+9–12+3–4+19–21. Average number of rows of teeth 131±22 with 29.9±0.6 rows per mm (n = 3).

Central teeth with bluntly pointed, ovate mesocones, shorter than base of tooth; ectocones vestigial. Lateral teeth with bluntly pointed ovate mesocones, length equal to base of tooth; small ectocones; endocones absent. Marginal teeth multicuspic, mesocone and endocone similar in length, ectocone smaller than endocone, occasionally subdivided.

Comparative remarks. Shells are close to Amplirhagada imitata (E. A. Smith, 1894) in overall shape, colouration, and sculpture, but see Fig. 8 . The type locality of A. imitata was restricted to Baudin Island by Solem (1981a). Amplirhagada imitata and A. solemiana exhibit the most sharply defined and prominent axial sculpture among all congeners except for A. indistincta . The anatomy of A. imitata is unknown for only dry shells were available to Solem (1981a). In between Baudin Island ( A. imitata ) and the two Osborn Islands ( A. solemiana and A. indistincta ) there are numerous other islands that are occupied by Amplirhagada species (e.g., Kingsmill, Corneille, Fenelon, and Descartes Islands) ( Fig. 1 ). Given the usually very restricted occurrence of Amplirhagada species and the marked genetic differentiation of A. solemiana and A. indistincta , it is considered very unlikely that either of them could be conspecific with A. imitata from Baudin Island, which is located in a considerable distance (c. 50 km NW of Osborn Islands). Based on shell features only, Solem (1981a) also synonymized A. burrowsena Iredale, 1938 from Vansittart Bay (c. 80 km E of Baudin Is) with A. imitata and reported this species to further occur in rainforest patches on the mainland (RFS 03/3, 11/1). These reports, however, almost certainly refer to extralimital populations. Species such as A. imitata , A. solemiana , A. indistincta , A. burrowsena and likely an undescribed species from the rainforest patches on the mainland may possibly form a group of sibling species that are not clearly differentiated by means of their shell morphology as is also known from the species group of A. mitchelliana Solem, 1981 from the Mitchell Plateau.

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 6. Genitalia of Amplirhagada solemiana n.sp., paratype WAM S36581 (13 February, scale 10 mm). Compare with Fig. 3 for labelling of structures.

Figure 7. Interior of penial chamber of Amplirhagada solemiana n.sp., paratypeAMS C463681 (13 February,scale 3 mm).Compare with Fig. 4 for labelling of structures.

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).