Gabbia napierensis, Ponder, 2003

Ponder, Winston F., 2003, Monograph of the Australian Bithyniidae (Caenogastropoda: Rissooidea), Zootaxa 230 (1), pp. 1-126 : 50-51

Gabbia napierensis n. sp.

Etymology Named for the Napier Range, western Kimberleys, the type locality.

Type material

Barnet Cave , NW end of Napier Range, SW facing side of Range , Kimberley, WA, 17° 15.000'S, 124° 42.000'E, in matted fine roots and dried algae under overhang of dry Ck bank and under stones in dry Ck bed, 30 AUG 1975, B. R. Wilson & S.M.Slack­Smith (Holotype, WAM S10978 ; paratypes WAM 1006­76, 628 wet, 7 dry, 9 on SEM stubs, AMS C.337372, 10; WAM 1005­76, 13; WAM 1004­76, 1; AMS, AMS C.337372, 10) .

Additional material examined

Western Australia: Mitchell Plateau, Mertons Ck, 14° 47.000'S, 125° 55.000'E, 19 AUG 1986, A.Kirke ( WAM 35­96 , 1 ); tributary of Mitchell R, small stream on rd to Mitchell Falls camping area, 14° 49.940'S, 125° 44.330'E, under rocks & in weed in pool, 22 JUN 1999, W.F.Ponder & G.Wilson ( AMS C.371623, 6; AMS C.371627, 2); Camp Ck, Mitchell Plateau, 14° 51.800'S, 125° 50.000'E, 19 AUG 1986, A.Kirke ( WAM 45­96 , 8 ); Drysdale R NP, Worriga Gorge, on Palmoondoora Ck, approx 2 km downstream from Morgan Falls, 14° 59.000'S, 126° 40.000'E, leaf litter in wooded & grassy flood scree, 16 AUG 1975, B. R.Wilson ( WAM 266­76 , 1 ); Ning Bing Bore, spring fed creek, 15° 14.940'S, 128° 40.660'E, on weed, 28 JUN 1996, W.F. Ponder, A.C. Miller, D.L.Beechey & V. Kessner ( AMS C.327877, 3; AMS C.381452, 2); near a cave, 3.5 km S of Ningbing Bore, Ningbing Ranges , E Kimberley, 15° 16.470'S, 128° 40.600'E, 26 JUN 1995, V.Kessner (V. Kessner coll'n 24306, 12; AMS C.318592, 4) .

G. cf. napierensis: Whim Ck area, W of Balla , Balla Ck nr NW corner of Mallina Stn, Tanganyika Gold Lease M 47/360, 20° 45.500'S, 117° 46.000'E, flood plain, 30 MAY 2000, S.Slack­Smith (WAM S12742 , 4 ; WAM S12743 , 9).

Description

Shell ( Figs 3L,M , 13F,G ) small (up to 5.1 mm in length), ovate conic, solid, with up to 4.9 convex whorls. Protoconch of about 1.5 smooth whorls. Teleoconch sculptured with fine, rather irregular collabral axial threads with traces of very fine spiral threads; base evenly convex; umbilicus closed by thickening behind outer lip. Aperture broadly ovate; peristome moderately thickened; outer lip prosocline. Colour: shell opaque to subtranslucent white; periostracum thin, white to slightly yellowish. Varices usually absent.

Dimensions. See Table 12 for dimensions of holotype and Appendix, Table 29 , for summary shell dimensions and whorl counts.

Operculum ( Fig. 15 G­I) typical of genus. Ovate, slightly concave, opaque, white; concentric growth ridges distinct; inner surface with muscle scar occupying most of surface, sculptured with low, irregular pustules.

Radula (Appendix Table 30 ; Fig. 16 G­J) typical of genus. Central teeth with 2­4 cusps on either side of median cusp which is 1.5 to about twice as long as adjacent cusps and its base nearly twice as wide; median cusp parallel­sided, with papilla­like end. Face of central tooth with 1­3 pairs of cusps that lie just inside lateral margin forming denticulate ridge, inner pair much larger than others, moderately large (nearly to about half total height of tooth); lateral margins straight, at about 60­70º; basal tongue long, narrow. Lateral teeth with cusp formula 2­4 + 1 + 3­4; with cutting edge about 3.0 ­ 3.7 length of lateral part of tooth; median cusp from slightly longer to nearly twice as long as adjacent cusps, tapering to blunt point; upper edge of lateral part of tooth at about 60­70º to cutting edge, lateral edge slightly concave to distinctly angled. Inner marginal teeth with 12­21 cusps, outer marginals with 7­11 cusps.

Animal not examined.

Distribution ( Fig. 12 ) and habitat. Kimberleys, north Western Australia mainly in pools in creek beds; sometimes in water flowing from caves.

Remarks

Gabbia napierensis has a narrow thickened callus behind the inner lip that covers the umbilical chink, a feature not seen in any other Australian bithyniid. In most features it is similar to G. vertiginosa , differing in its more thickened peristome, callosity over the umbilical chink and smaller size. It is also similar to G. obesa n. sp. and is contrasted with that species below (see remarks under G. obesa ). Gabbia kendricki is possibly the sister species of G. obesa + G. napierensis . It also has a papilla­like median cusp on the central teeth, but differs in being larger, with a thinner peristome. The cusps on the lateral and marginal teeth are also longer.

Shells from Mallina Stn (WAM S12742 , 3) on the northern edge of the Pilbara region, are very similar to G. napierensis but are smaller than typical specimens.

Figures

FIGURE 3.Protoconchs and microsculpure: A – E, Gabbia vertiginosa, A, B, AMS, C.308015, C – E, AMS, C.332890; F – I, Gabbia campicola, F – H, paratype, AMS, C.332829, I, AMS, C.318702; J, Gabbia kendricki, paratype, AMS, C.203378; K, Gabbia pallidula, paratype, AMS, C.308007; L, M, Gabbia napierensis, paratype, AMS, C.337372; N, O, Gabbia rotunda, paratype, AMS, C.400134; A, B, F ­ J, L ­ N, protoconch, C ­ E, K, O, microsculpture; Scales: A ­ B, F ­ J, L, 100 m, C ­ D, N, 200 m, E, K, O, 20 m, M, 500 m.

FIGURE 12. Distribution of Gabbia kendricki (), G. napierensis (), G. cf. napierensis () and G. tumida (o).

FIGURE 13. Shells: A, B, Gabbia campicola, AMS, C.318702; C, D, Gabbia pallidula, C, paratype, AMS, C.308007, D, holotype AMS, C.417667; E, Gabbia davisi, holotype, AMS, C.417668; F, G, Gabbia napierensis, F, paratype, AMS, C.337372, G, holotype, S10978; H, I, Gabbia cf. rotunda, AMS, C.385439; Scales: A – D, F – I, 500 m, E, 1mm.

FIGURE 15. Opercula: A, B, Gabbia campicola, AMS, C.318702; C, D, Gabbia pallidula, paratype, AMS, C.308007; E, F, Gabbia davisi, paratype, AMS, C.417617; G ­ I, Gabbia napierensis, paratype, WAM, 1006 ­76; J, K, Gabbia cf. rotunda, AMS, C.385439; L, M, Gabbia rotunda, paratype, AMS, C.400134; A, C, E, G, I, J, L outer side, B, D, F, H, K, M inner side. Scales: 500 m.

FIGURE 16. Radulae: A, Gabbia pallidula, paratype, AMS, C.308007; B, C, Gabbia campicola, AMS, C.318702; D, Gabbia fontana, AMS, C.307906; E, F, Gabbia davisi, paratype, AMS, C.417617; G – J, Gabbia napierensis, paratype, –AMS, C.337372; K, L, Gabbia cf. rotunda, AMS, C.385439. A, B, E, H, I, L, central teeth, C, half row of teeth, D, central and lateral teeth, F, J, lateral teeth, G, marginal teeth, K, lateral and marginal teeth; Scales: 20 m.