Gabbia davisi, Ponder, 2003

Ponder, Winston F., 2003, Monograph of the Australian Bithyniidae (Caenogastropoda: Rissooidea), Zootaxa 230 (1), pp. 1-126: 47-49

publication ID

http://doi.org/ 10.11646/zootaxa.230.1.1

publication LSID

lsid:zoobank.org:pub:AE9A8BE3-1CBD-4958-991A-C6EC1F203AF2

DOI

http://doi.org/10.5281/zenodo.5019138

persistent identifier

http://treatment.plazi.org/id/0C12051D-2343-FFCB-FECC-F9FECF91B42D

treatment provided by

Felipe

scientific name

Gabbia davisi
status

n. sp.

Gabbia davisi   n. sp.

Etymology

Named for Assoc. Prof. Andrew Davis, University of Wollongong, NSW, Australia, in appreciation of his companionship and assistance in the field.

Type material

Lake Huffer Stn , large spring near lake, pool at base of spring, Qld, 22° 15.660'S, 145° 20.430'E, in mud, 4 OCT 2002, W.F.Ponder & A.Davis (Holotype, AMS C.417668; paratypes AMS C.417617, 414 wet, 5 on SEM stub; QM MO71711, 10) GoogleMaps   .

Description

Shell ( Fig. 13E View FIGURE 13 ) medium (up to 6.7mm in length), broadly­ovate­conic, up to 4.6 convex whorls. Protoconch of about 1.3­1.5 almost smooth whorls, with traces of extremely fine spiral striae, last half whorl with weak axial threads. Teleoconch sculptured with fine collabral growth lines only; base evenly convex; umbilicus narrowly open, wider in juveniles. Aperture broadly ovate; peristome thin; inner lip slightly thickened, outer lip thin, prosocline. Colour: shell opaque to semi­translucent; periostracum pale yellowish to yellowish­brown. A few thin, rather indistinct, pale brown varices sometimes present.

Dimensions. See Table 9 for dimensions of holotype and Appendix, Table 29 View TABLE 29 , for summary shell dimensions and whorl counts.

Operculum ( Fig. 15E,F View FIGURE 15 ) typical of genus. Ovate, white; with several distinct concentric growth ridges; inner surface with muscle scar occupying most of surface, sculptured with weak pustules.

Radula (Appendix Table 30 View TABLE 30 ; Fig. 16E,F View FIGURE 16 ) typical of genus. Central teeth with 4­5 cusps on either side of median cusp which is up to about 1.5 length of adjacent cusps and its base up to about 1.5 width; median cusp tapering and pointed. Face of central tooth with 1 pair of prominent cusps about third to nearly half of tooth height; lie inside lateral margin with weakly denticulate ridge representing up to 4 additional rudimentary basal denticles; lateral margins straight to slightly concave, at about 50­60º; basal tongue rather long, narrow and blunt. Lateral teeth with cusp formula 3 + 1 + 3­4; cutting edge slightly less than half length of lateral part of tooth; median cusp about 1.5 length of adjacent cusps, tapering with blunt to pointed end; inner side with excavation at base, upper edge of lateral part of tooth at about 70º to cutting edge, lateral edge strongly concave. Inner marginal teeth with 15­21 cusps, outer marginals with 8­9 cusps.

Head­foot grey to black except for tentacles distal to eyes. Tentacles unpigmented except for grey stripe in middle. Mantle roof black with small to large, close white spots and patches giving it netted appearance. Visceral coil unpigmented to black dorsally.

Anatomy. Gill with apices at about third gill width from right; 55­61 filaments (n=3). Osphradium slightly posterior to middle of gill or at middle. Penis ( Fig. 7C View FIGURE 7 ) and accessory lobe about equal in length to penial lobe or slightly longer, accessory lobe expanded to markedly expanded distally; accessory gland very long and tightly coiled. Pallial oviduct similar to G. vertiginos   , with narrow bursa copulatrix reaching edge of albumen gland (AMS C.417617).

Distribution ( Fig. 9 View FIGURE 9 ) and habitat. Known only from a single spring on Lake Huffer Station in western Queensland where it was found in a small, shallow muddy pool near the head of a large spring and, abundantly, in a large, shallow muddy pool at the base of the spring outflow.

Remarks

This species closely resembles G. campicola   in shell characters and measurements and in radular characters. Its whorls tend to be more convex and it is much more distinctly umbilicate, especially in juveniles which are rather widely umbilicate. Gabbia davisi   differs from G. campicola   in the gill apices being at about a third of the gill width (compared with on or close to the right edge). It also differs from G. campicola   and all other similar species in the accessory prostate being unusually very long, narrow and tangled. The pigmented mantle, long accessory gland and umbilicus separate this species from G. pallidula   . Gabbia davisi   is found in a spring very near the type locality of G. pallidula   , and is contrasted in the remarks under that species. Gabbia fontana   n. sp., another spring endemic, is contrasted below under that taxon.

Despite the apparent lack of shell differences, a disciminant analysis including all similar species from NE Queensland separates this species reasonably well from G. campicola   and other similar taxa ( Figs 10D View FIGURE 10 , 17A, C View FIGURE 17 ; Tables 10 View TABLE 10 , 11).