Gabbia spiralis Ponder 2003, n.sp.
Creators: name: Ponder, Winston F.
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Bithyniidae
Gabbia
Gabbia spiralis

description: Gabbia spiralis n.sp.
Etymology Spiralis (L.) – spiral.
Type material
Waterhole on Eight Mile Ck on Karumba ­ Chillagoe Rd, Qld, 17° 12.217'S, 141° 12.1'E, on weed etc. mainly along edges, 1 JUN 1997, W.F.Ponder, V.Kessner & D.L.Beechey (Holotype, AMS C.417682; paratypes AMS C.331849, 655, 16 dry, 6 on SEM stub; QM MO71720, 12; NTM P21378, 8).
Additional material examined
Queensland: Waterhole W of Pelican Ck, 10.5 km SSE of Wyaaba Ck Crossing, 16° 46.920'S, 141° 59.230'E, on grass & substrate, 1 JUN 1997, W.F. Ponder, V. Kessner & D.L. Beechey (AMS C.332834, 20+); waterhole 300m N of Gilbert R on Burke Developmental Rd, 17° 9.880'S, 141° 46.120'E, on mud & weed along edges, 1 JUN 1997, W.F.Ponder, V. Kessner & D.L.Beechey (AMS C.338815, 20+); waterhole in river flood channel of Gilbert R, ca. 0.2 km S of Gilbert R, 17° 10.450'S, 141° 45.990'E, on weed & mud, 1 JUN 1997, W.F.Ponder, V.Kessner & D.L.Beechey (AMS C.326799, 20+); Twelve Mile Ck waterholes at Karumba to Normaton Rd, 17° 31.730'S, 141° 9.570'E, 31 MAY 1997, W.F.Ponder, V.Kessner & D.L. Beechey (AMS C.332839, 20+).
Description
Shell (Figs 1L, 26D,G, 36C,D) small to moderate (up to 5.6 mm in length), broadlyovate to ovate­conic, with up to 4.0 convex, narrowly shouldered whorls. Protoconch of 1.3­1.5 whorls, smooth except for traces of fine spiral striae. Teleoconch sculptured with numerous strong spiral cords (about 25­30 spiral cords on last whorl) with about equal to linear interspaces and crossed by fine collabral growth lines; one cord on upper part of whorl slightly stronger, with weak shoulder above; base evenly convex; umbilicus open, moderate size. Aperture broadly ovate; peristome moderately thickened in adults; outer lip prosocline. Colour: shell opaque to sub­translucent; periostracum thin, yellowish­white to orange­brown. A few thin, dark varices typically present.
Dimensions. See Table 27 for dimensions of holotype and Appendix, Table 29, for summary shell dimensions and whorl counts.
* Tip of spire eroded, estimated actual number in brackets.
Operculum (Fig. 32N,M) typical of genus. Ovate, translucent and colourless to yellowish­white or white; concentric growth ridges poorly demarcated (outer surface often appears almost smooth) to distinct; inner surface with muscle scar occupying much of surface, sculptured with folds, pits or pustules.
Radula (Appendix Table 30; Fig. 37D,E) typical of genus. Central teeth with 4­5 cusps on either side of median cusp which is about 1.3­1.6 longer than adjacent cusps and its base about twice as wide; median cusp evenly tapering to sharp point to parallel sided proximally with peg­like projection distally (Fig. 37E). Face of central tooth with 3­5 pairs of cusps that extend well inside lateral margin and parallel to it forming cuspate ridge, inner pair larger than others but second pair almost equal in size; inner pair about half total height of tooth; lateral margins straight to slightly concave, at about 50­60º; basal tongue short, blunt to pointed. Lateral teeth with cusp formula 4­5 + 1 + 4­5; with cutting edge about third length of lateral part of tooth; median cusp up to about 1.4 length of adjacent cusps, parallel sided to slightly tapering, distal end bluntly pointed to rounded; upper edge of lateral part of tooth at about 50­60º to cutting edge, lateral edge slightly to moderately concave. Inner marginal teeth with 21­24 cusps, outer marginal teeth narrow, with 8­11 cusps.
Head­foot with pale grey to black snout, pigment extending onto middle part of head in more heavily pigmented specimens, tentacles with wide grey to black longitudinal streak in middle part; bases of tentacles, foot and siphon unpigmented. Mantle roof unpigmented, or with grey or black pigment and tiny white spots in anterior half fading to absent posteriorly, mantle edge unpigmented. Visceral coil unpigmented or with dorsal grey to black smudge.
Anatomy. Gill with apices at quarter to third gill width from right; 64­67 filaments (n=3). Osphradium slightly anterior to middle of gill. Penis (Fig. 7H) with accessory lobe slightly shorter than penial lobe, distal end swollen; accessory gland moderately long. Pallial oviduct (Fig. 34C) similar to G. vertiginosa, bursa copulatrix rather narrow, and almost reaches posterior pallial wall (AMS C.331849).
Distribution (Fig. 22) and habitat. Coastal plains, western base of Cape York, Gulf of Capentaria. In billabongs and pools on mud, although often associated with macrophytes and algae.
Remarks
This species and the next differ from all other Australian bithyniids in dominant spiral sculpture. Gabbia spiralis differs from G. carinata n. sp. in having more numerous, relatively weaker spiral cords, a taller spire and smaller umbilicus. See the remarks under G. carinata relating to the generic placement of spirally lirate species.
description: Published as part of Ponder, Winston F., 2003, Monograph of the Australian Bithyniidae (Caenogastropoda: Rissooidea), pp. 1-126 in Zootaxa 230 (1) on pages 104-105, DOI: 10.11646/zootaxa.230.1.1, http://zenodo.org/record/5019111