Edgbastonia (Barcaldinia) corrugata subsp. umbilicata Zhang 2019, n. subsp.
Creators: name: Zhang, - H.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Tateidae
Edgbastonia
Edgbastonia corrugata
Edgbastonia (barcaldinia) corrugata umbilicata

description: Edgbastonia (Barcaldinia) corrugata umbilicata n. subsp.
Material examined. Holotype: Queensland, Myross Station, main spring, 22° 47' 06" S, 145° 26' 00" E, at spring edge, amongst grass and on mud, W.F. Ponder & A. Davis, 6 Oct 2002, C.479946. Paratypes: Same data, C.415845, 20+; QM MO85774, 5. Other material examined: Queensland, Myross Station, main spring, 22° 47' 07" S, 145° 26' 05" E, W.F. Ponder, R. Fairfax & R. Fensham, 13 Sep 2006, C.458219, 20+; 22° 47' 42" S, 145° 26' 26" E, 1 Jul 2008, R.J. Fensham & R. Fairfax, C.462094, 10+; 22° 47' 27" S, 145° 26' 27" E, 1 Jul 2008, R.J. Fensham & R. Fairfax, C.462092, 20+. Other material from the same locality: C.483045 12; C.483114, 20+; C.483112, 20+; C.483107, 20+; C.483110, 5; C.483113, 20+; C.483111, 5; C.483044, 20+; C.483108, 20+; C.483109, 3, C.505944,20+; C.505941,1; C.505949, 20+; C.505945, 20+, C.505951, 20+, C.505943, 1; C.505950, 12; C.505948, 5; C.505942, 13; C.505946, 5.
Shell (Fig. 13G). Ovate, spire outline moderately convex, normally coiled, translucent. Length 2.2–2.6 mm (mean 2.4 mm), width 1.8–2.5 mm (mean 2.1 mm). Protoconch about 1.2–1.3 whorls, distinctly pitted. Teleoconch whorls weakly convex, evenly rounded, total number 3.2–4.3 (mean 3.8). Umbilicus moderately wide. Aperture ovate, inner lip narrow, thin or medium, in partial contact to slightly separated from parietal wall, outer lip thin or medium. Periostracum moderately developed, pale yellow or yellow-brown.
Operculum (Fig. 14I, J). Transparent, colourless, slightly concave. Inner side lacking white smear, simple.
Head-foot and external body. Snout, tentacles unpigmented or pigmented, neck, dorsal and lateral foot and opercular lobes unpigmented, mantle roof unpigmented or weakly pigmented, visceral coil weakly pigmented.
Mantle cavity. Ctenidium well-developed, filaments 24–28, broadly triangular, apex right edge. Osphradium narrowly oval, towards posterior end of ctenidium, length relative to gill 0.22–0.31. Hypobranchial gland moderately developed. Rectum with U-shaped bend, faecal pellets longitudinally orientated or orientated obliquely or sideways, anus at mantle collar or a little behind it. Kidney half or more in roof of mantle cavity. Renal gland transverse. Pericardium half or more in roof of mantle cavity, overlapping posterior end of ctenidium.
Radula (Fig. 19C, D). Central teeth with cusp formula 3–4+3–5, basal cusps 1+1+1; median cusp sharp, about twice as long as adjacent cusps. Lateral teeth with cusp formula 3–4+1+3–4; main cusp sharp, about twice as long as adjacent cusp on outer side, slightly longer than adjacent cusp on inner side. Inner marginal teeth with 15–19 cusps. Outer marginal teeth with 12–15 cusps.
Female reproductive system (Fig. 16J, K). Ovary weakly to strongly lobed. Renal oviduct with rather small, U-shaped arch. Seminal receptacle anterior to bursa, oval, duct intermediate; sometimes orientated sperm in renal oviduct and/or bursal duct. Bursa copulatrix overlapping albumen gland on left, round or triangular, shorter than albumen gland, bursal duct enters bursa antero-ventrally, bursal duct joins coiled oviduct little behind posterior mantle cavity wall. Albumen gland partly in mantle cavity. Capsule gland with two distinct glandular zones, thick in cross section, markedly indented by rectum. Anterior vestibule large, opening anterior to capsule gland, short, cowl and/or gutter associated with oviduct opening present.
Male reproductive system (Figs. 17F, 18G). Prostate gland less than half in mantle roof, bean-shaped, thick in cross section. Posterior pallial vas deferens coiled, anteriorly slightly undulating. Penis towards middle of head, intermediate, distal end tapering, terminal papilla absent, large non-glandular distal lobe present.
Etymology. Umbilicus—Latin, navel. A term used in gastropods for a depression or perforation in the base of the shell.
Distribution and habitat. Known only from a large, shallow spring-fed pool on Myross Station (Fig. 1). Abundant, living in fine silt on the bottom of the pool. It was not found in vegetated areas around the edge of the pool.
Remarks. This subspecies is very similar to Ed. (B.) corrugata corrugata but differs in having less welldeveloped axial sculpture, and the inner lip is in contact with the parietal wall or only slightly separated from it, instead of being widely separated. The female genital system is very similar to that of Ed. (B.) corrugata corrugata but differs in having a smaller, shorter bursa copulatrix with a narrower duct. The central teeth of the radula in the new subspecies are unusual in having only a single pair of basal cusps developed (cf., Ponder & Clark 1990, fig.8D, E), although a rudimentary second cusp is rarely seen.
A discriminant function analysis using five shell measurements of the four large globular species, Ed. corrugata corrugata, Ed. corrugata umbilicata, Ed. edgbastonensis and Ed. coreena, gave the following results (Wilks’s Lambda 0.236 p<0.000); overall 78% were correctly classified with Ed. coreena being the least correctly placed (42%) with specimens distributed between Ed. corrugata corrugata and Ed. edgbastonensis while Ed. corrugata corrugata was 77% correctly classified with some specimens being incorrectly classified as Ed. edgbastonensis and Ed. corrugata umbilicata. Ed. edgbastonensis was only 64% correctly classified with most of those going to Ed. corrugata corrugata. Ed. corrugata umbilicata was the most successfully classified (98%) with only one specimen being misclassified as Ed. corrugata corrugata (Fig. 20A).
The new subspecies is unusual in that the egg capsules are laid on the shell, a habit not observed in other taxa, including the typical subspecies, and this is presumably due to the lack of hard substrate and vegetation in the habitat it occupies.
Various water birds such as spoonbills (Platalea sp., Threskiornithidae) and several species of ducks were common in the pool and were feeding in the mud, suggesting that this rather abundant snail is probably utilised as a food item.
description: Published as part of Zhang, - H., 2019, New taxa of Tateidae (Caenogastropoda, Truncatelloidea) from springs associated with the Great Artesian Basin and Einasleigh Uplands, Queensland, with the description of two related taxa from eastern coastal drainages, pp. 1-67 in Zootaxa 4583 (1) on pages 28-31, DOI: 10.11646/zootaxa.4583.1.1, http://zenodo.org/record/2637603