Edgbastonia (Barcaldinia) cf. pallida (Ponder & Clark, 1990)

Material examined. Queensland, Myross Station, main spring, 22° 47' 07" S, 145° 26' 05" E, edges in weed, W.F. Ponder, R. Fairfax & R. Fensham, 13 Sep 2006, C.479947 (figured specimen); same data, C.457755, 20+; small spring, 22° 46' 32" S, 145° 26' 17" E, under two large gum trees, W.F. Ponder, R. Fairfax & R. Fensham, 17 Sep 2006, C.458218, 10; C.478236, 2.

Shell (Fig. 13B). Elongately ovate, spire outline slightly convex, translucent or opaque. Length 1.4–1.9 mm (mean 1.7 mm), width 0.8–1.1 mm (mean 1.0 mm). Protoconch of about 1.3 whorls. Teleoconch whorls convex, evenly rounded, total number 3.4–4.4 (mean 3.9). Umbilicus represented by chink only. Aperture ovate, inner lip narrow, thin or medium, slightly separated along whole length of parietal wall, outer lip thin or medium. Periostracum moderately developed, white or yellow-brown or brown or reddish-brown.

Operculum (Fig. 14B, C). Transparent, colourless, flat. Inner side lacking white smear, simple.

Head-foot and external body. Snout, tentacles and dorsal and lateral foot unpigmented, neck and opercular lobes pigmented, mantle roof and visceral coil unpigmented to densely pigmented.

Mantle cavity. Ctenidium well-developed, filaments 18–21, broadly triangular, apex right edge. Osphradium narrowly oval, towards posterior end of ctenidium or at middle of ctenidium, length relative to gill 0.21–0.4. Hypobranchial gland moderately developed. Rectum with U-shaped bend, anus behind mantle collar. Kidney extends for about third of length into mantle cavity roof. Renal gland transverse. Pericardium extends for about third of length into mantle cavity roof, abutting posterior end of ctenidium.

Radula (Fig. 15C, D). Central teeth with cusp formula 3–5+1+3–4, basal cusps 2+2; median cusp long, pointed, narrow, about twice as long as adjacent cusps. Lateral teeth with cusp formula 3–4+1+4–5; main cusp pointed, narrow, curved inwards, less than twice as long as adjacent cusps. Inner marginal teeth with 16–25 cusps. Outer marginal teeth with 16–25 cusps.

Female reproductive system (Fig. 16C, F). Ovary simple sac. Renal oviduct with two weak undulations, anterior-most forming shallow U-shape. Seminal receptacle absent; orientated sperm in renal oviduct and/or bursal duct. Bursa copulatrix behind albumen gland, vertically-oval, shorter than albumen gland, bursal duct enters bursa mid anteriorly or antero-ventrally, bursal duct joins coiled oviduct little behind posterior mantle cavity wall or well behind posterior mantle cavity wall. Albumen gland partly in mantle cavity. Capsule gland with three distinct glandular zones, medium thickness in cross section, markedly indented by rectum. Anterior vestibule not much expanded, opening subterminal and on face of capsule gland, short, cowl and/or gutter associated with oviduct opening present.

Male reproductive system (Fig. 17B, 18B, C). Prostate gland less than half in mantle roof, bean-shaped, medium in cross section. Posterior pallial vas deferens coiled, anteriorly straight or slightly undulating. Penis towards middle of head, well down neck, distal part lacking lobes, terminal papilla long.

Distribution and habitat. Found in a few springs on Myross Station (Fig. 1).

Remarks. This material is very similar to Ed. (B.) pallida in shell characters but differs from that taxon, and all others in this group, in its smaller, more oval bursa copulatrix and in lacking a seminal receptacle. However, because it is not well differentiated from Ed. (B.) pallida in the molecular analysis (Fig. 31), and because of the considerable similarity in shell characters and allopatric distribution, it is not named. The anatomical differences could possibly be accounted for by the material not being fully sexually mature. Further investigation is required to settle the status of the Myross samples.

A discriminant function analysis of five shell measurements of the taxa in the Ed. colmani-pallida group successfully separated the species but 82% of Ed. pallida and only 72% of Ed. cf. pallida were correctly classified (Wilks’s Lambda 0.040 p<0.000) (Fig. 20B). In contrast, 96% and 95% respectively of Ed. colmani and Ed. hufferensis were correctly classified. An analysis including only the two forms of Ed. pallida only marginally improved the discrimination of these two taxa, with 75% correctly discriminated (Wilks’s Lambda 0.713 p=0.035).