Gabbia kendricki, Ponder, 2003

Ponder, Winston F., 2003, Monograph of the Australian Bithyniidae (Caenogastropoda: Rissooidea), Zootaxa 230 (1), pp. 1-126 : 38-41

Gabbia kendricki n. sp.

Etymology

Named after George Kendrick, Western Australian Museum (retired) in recognition of his considerable efforts in collecting the non­marine molluscan fauna of Western Australia.

Type material

Murchison R Bridge , on Great Northern Highway, WA, 27° 49.667'S, 114° 41.500'E, 20 AUG 1968 (Holotype WAM S10877 ; paratypes WAM 991­85, 135 wet, 11 dry, 4 on SEM stub, paratypes AMS C.203378, 5). Additional paratypes: same locality, 02 MAR 1966, B. R . Wilson & G.W.Kendrick ( WAM 1064­66 , 33 wet, 2 dry, WAM 1064­66, 1),, east of bridge, 10 SEP 1975, B. R . Wilson & S.M.Slack­Smith ( WAM 8­96 , 672 dry), same locality, 12 AUG 1961, B. R . Wilson & G.W.Kendrick ( WAM 42­96 , 66 wet, 2 dry; WAM 7­96, 5); Murchison R Bridge , in mud, under stones at flood line, 18 SEP 1968 ( WAM 38­ 96 , 99 wet, 3, dry), 03 APR 1974, Landye et al. ( USNM 883293 , 511 wet, 38 dry), Four Mile Pool, below bridge, rocks and water weeds in shallow, slow river, 01 SEP 1989, V.Kessner ( AMS C.346425, 8) .

Additional material examined

Western Australia: Willie Ck , N of Broome, 17° 46.000'S, 122° 12.000'E ( MV F 4671 , 14 ) ; Broome, 17° 58.000'S, 122° 14.000'E, 1957 ( AMS C.307895, 5); Fraser R, Bungarragut Pool , 17° 23.000'S, 123° 11.000'E, 23 APR 1998, M. Smith ( AMS C.326798, 7); Murchison R, 25° 42.000'S, 118° 6.000'E ( AMS C.307877, 7); same locality, 28 MAY 1975, F.Jones ( WAM 14­96 , 6 ), JUL 1963 ( AMS C.382368, 20+); 32 km W Yallalong Stn HS, Murchison R, 27° 25.000'S, 115° 29.000'E, 12 NOV 1979, J. Blyth ( MV F 54858 , 20 +) ; Murchison R, Kalbarri Gorge, below Ross Graham Lookout , 27° 39.000'S, 114° 28.000'E, 8 MAY 1968, J.L.Bannister ( WAM 15­96 , 1 ) ; same locality, near river bank, 9 JUL 1967, J. White ( WAM 13­96 , 1 ) ; Yalgoo, 28° 21.000'S, 116° 41.000'E, 1980, I. C. Carnaby ( WAM 6­96 ) ( AMS C.380779, 7); Arrowsmith R, Arramall Cave , E 22, 29° 30.000'S, 115° 30.000'E, in flood debris, 31 MAR 1973, J.Lowry ( WAM 17­96 , 4 , WAM 18­96, 5, WAM 10­96, 1; WAM 12­96, 1; WAM 16­96, 1; WAM 11­96, 3); Arro Swamp, 29° 44.000'S, 115° 10.000'E, seasonal swamp, 22 SEP 1999 ( AMS C.405609, 6); near Eneabba, 3ml W of Lake Indoon, 29° 52.000'S, 115° 9.000'E, clay pan, 16 OCT 1976, J.White ( WAM 5­96 , 6 ) .

Description

Shell ( Figs 2L , 3J ) of moderate size for family (up to 6.5 mm in length), broadly­ovate to ovate conic, of up to 4.9 convex whorls. Protoconch of about 1.5 smooth whorls. Teleoconch sculptured with fine collabral growth lines and, in some specimens, numerous very fine spiral lines (not raised as sculpture) present, a few specimens have a few weak, spiral ridges on last whorl; base evenly convex; umbilicus usually narrowly open in adults and juveniles, sometimes closed and chink­like. Aperture broadly ovate; peristome thin to slightly thickened; outer lip prosocline. Colour: shell semitranslucent to transparent, periostracum thin, yellowish­white to reddish­brown. One or a few thin, dark brown, slightly raised varices often present.

Dimensions. See Table 6 for dimensions of holotype and Appendix, Table 29 , for summary shell dimensions and whorl counts.

Operculum ( Fig. 4 J­L) typical of genus. Ovate, white; concentric growth ridges indistinct to distinct; inner surface with muscle scar occupying most of surface, sculptured with small, weak, rather even pustules.

Radula (Appendix Table 30 ; Fig. 11H, I ) typical of genus. Central teeth with 3­4 cusps on either side of median cusp which is about 1.5­2.0 longer than adjacent cusps and its base about twice as wide; median cusp initially parallel­sided, distal part papilla­like to almost triangular, tapering to blunt point. Face of central tooth with 3­4 pairs of cusps that commence well inside lateral edge and move closer to lateral margin ventrally forming separate dentate ridge, inner pair about twice as large as adjacent cups, rather small (about 1/7 total height of tooth); lateral margins concave, at about 50­60º; basal tongue broad, rounded. Lateral teeth with cusp formula 2­3 + 1 + 4­5; with cutting edge about 0.4 length of lateral part of tooth; median cusp up to nearly twice as long as adjacent cusps, parallelsided with rounded end; upper edge of lateral part of tooth at about 50º to cutting edge, straight. Inner marginal teeth with 18­21 small cusps, outer marginals with 10­11 cusps.

Head­foot unpigmented other than snout (dorsal black), mantle black, mottled with large white spots.

Anatomy. Gill with apices at 0.25­0.3 gill width from right; 66­75 filaments (n=2). Osphradium opposite middle of gill. Penis and accessory lobe long and narrow; accessory gland medium length. Pallial oviduct similar to G. vertiginosa but with shorter, wider bursa copulatrix (WAM 42­96, USNM 883293).

Distribution ( Fig. 12 ) and habitat. This species is known mainly from the Murchison R, north of Geraldton, Western Australia, with a few records from the vicinity of Broome. It is often found with the superficially similar Coxiella (Coxielladda) cf. gilesi (Angas 1877) in what is presumably rather saline water.

Remarks

Gabbia kendricki is similar in shell morphology to G. vertiginosa but differs in usually being narrowly umbilicate. The central teeth of the radula differ in having concave lateral margins and the basal tongue broadly rounded in contrast to the narrow, elongate basal tongue seen in the type species. In addition, the penial accessory gland is shorter and the penis and accessory lobes longer (confirmed in three different lots of specimens) and the gill has the apices at about 0.25­0.3 from the right side (they are usually closer to, or on the right margin in G. vertiginosa ). The pallial oviduct is generally similar except for having a shorter, wider bursa copulatrix.

Despite the apparent similarity in shell features, a discriminant function analysis showed that 90% of specimens of G. kendricki were successfully classified when compared against G. vertiginosa , G. iredalei and G. campicola ( Table 7 ).

Available material from the vicinity of Broome is poor and, particularly in view of the markedly disjunct distribution (which in large part can be explained by the intervening Great Sandy Desert), their association with this taxon requires further investigation.

Figures

FIGURE 2. Shells: A – E, Gabbia vertiginosa, A, AMS, C.203392, B ­ D, AMS, C.308015, E, AMS, C.332890; F, Gabbia iredalei, AMS, C.337418; G – K, Gabbia campicola, G, AMS, C.344345, H, holotype, C.417664, I, paratype, C.332829, J, K, MV, F.54869; L­N, Gabbia kendricki, L, holotype, WAM S10877, M,N, paratypes, AMS C.203378; Scales: A – E, L­N, 500 m, F, 2 mm, G – K, 1mm.

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 4. Opercula: A ­ E, Gabbia vertiginosa, A, B, AMS, C.203392, C, D, AMS, C.308015, E, AMS, C.332890; F, Gabbia iredalei, MV F.54870; G ­ I, Gabbia campicola, paratype, AMS, C.332829; J ­ L, Gabbia kendricki, AMS, C.337372; A, C, E ­ H, J, K, outer side; B, D, I, L, inner side; Scales: 500 m.

FIGURE 11. Radulae: A – G, Gabbia campicola, A, F, G, paratype, AMS, C.332829, B,C, MV, F.54869, D, E, AMS, C.344345; H, I, Gabbia kendricki, WAM, AMS, C.203378; A, B, half rows of teeth, C, D, F, H, central teeth, E, G, I, lateral teeth; Scales: 20 m.

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