Monograph of the Australian Bithyniidae (Caenogastropoda: Rissooidea)
Author
Ponder, Winston F.
text
Zootaxa
2003
2003-07-04
230
1
1
126
http://biotaxa.org/Zootaxa/article/view/zootaxa.230.1.1
journal article
5480
10.11646/zootaxa.230.1.1
a880f550-16bc-4733-9407-d09212861392
11755334
5019111
AE9A8BE3-1CBD-4958-991A-C6EC1F203AF2
Gabbia carinata
n.sp.
Etymology Carinatus
(L.) – keeled.
Type
material
Two mudholes, by Walker Ck, Qld,
17° 28.030'S
,
141° 10.790'E
, in fine mud around edges,
31 MAY 1997
,
W.F.Ponder
,
V.Kessner
&
D.L.Beechey
(
Holotype
,
AMS
C.417683;
paratypes
AMS C.331877, 1018 wet, 30+ juveniles, 10 dry, 4 on SEM stubs; NTM P21379, 15; QM MO71721, 10)
.
Additional material examined
Northern Territory
:
Tawarrila Ck, S.
of
Bing Bong, W
.
Gulf
of
Carpentaria
,
15° 46.580'S
,
136° 25.170'E
, amongst macrophytes,
23 AUG 1994
,
W.F.Ponder
,
G.Wilson
&
V.Kessner
(
AMS
C.327927, several)
.
Queensland
:
billabong S of
Tully Inlet
,
2.5 km
W of Settlement Ck
,
Wollogorang Stn
,
Gulf
of
Carpentaria
,
16° 45.700'S
,
138° 8.950'E
,
25 AUG 1994
,
V.Kessner
(
VKC
23956,
20
+; AMS C.318640, 6); billabong
E of Settlement Ck
crossing,
Wollogorang Stn
,
Gulf
of
Carpentaria
,
16° 53.450'S
,
138° 9.280'E
,
25 AUG 1994
,
V.Kessner
(
VKC
23955,
20
+; AMS C.318576, 6); billabong above
Tully Inlet, W.
of
Mornington Is
.,
Gulf
of
Carpentaria
,
16° 45.710'S
,
138° 8.960'E
, amongst weed & macrophytes,
25 AUG 1994
, W.F.Ponder,
G.Wilson
&
V.Kessner
(
AMS
C.327879, several; AMS C.327893, 20+); billabong off road to beach nr
Tully Inlet
, W. of
Mornington Is
,
Gulf
of
Carpentaria
,
16° 46.900'S
,
138° 10.140'E
,
25 AUG 1994
,
W.F.Ponder
,
G.Wilson
& V.
Kessner
(
AMS
C.327883, 20+); permanent billabong E of
Settlement Ck.
,
Wollogorang Stn
,
Gulf
of
Carpentaria
,
16° 46.920'S
,
138° 10.170'E
,
25 AUG 1994
,
V.Kessner
(
VKC
23957,
20
+; AMS C.318618, 6);
65 km
by road
NE of Woologorang
HS
, nr
Qld
border
,
Gulf
of
Carpentaria
,
16° 47.000'S
,
138° 10.170'E
, in shallow billabong, in mud,
29 AUG 1988
,
V.Kessner
(
AMS
C.300776, 3; VKC 13881, 14;
AMS C.318591, 3);
7 km
SSE Scrutton Ck
crossing,
Gulf
of
Carpentaria
,
17° 35.750'S
,
138° 26.420'E
, small billabong in
Cliffdale Ck
drainage,
30 AUG 1988
,
V.Kessner
(
AMS
C.300777, 1; VKC 13882, 1);
Jam Tin Yard
,
Devils Gate Stn
,
17° 24.600'S
,
138° 34.950'E
, on mud,
24 MAY 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.326805, sev);
M
Lagoon
next to M
Ck on Normanton
Burketown Rd
,
18° 6.070'S
,
140° 16.880'E
, on mud amongst vegetation,
29 MAY 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.331861, 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.332842, 20+);
Brannigan Ck
at
Karumba
to
Normanton Rd
(side channel with waterholes),
17° 28.660'S
,
141° 10.600'E
,
31 MAY 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.331863, 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.333670, 1;
AMS C.381244, 5); waterhole on
Dogwood Ck on Burke Developmental Rd
,
16° 51.730'S
,
141° 58.060'E
, on weed & mud,
1 JUN 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.326793, 20+);
Clarks Lagoon
,
Dunbar Stn on Burke Dev Rd
,
16° 1.030'S
,
142° 25.010'E
, on weed,
3 JUN 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.381474, 14);
Nolan Ck
at
Burke Developmental Rd
,
16° 48.670'S
,
144° 10.090'E
,
4 JUN 1997
,
W.F.Ponder
,
V.Kessner
& D.L.
Beechey
(
AMS
C.346293, 20+)
.
Description
Shell (
Figs 26H,J
,
36E,F
) small (up to
5.6 mm
in length), trochiform with strong spiral ridges, up to 4.4 convex whorls shouldered in upper third by uppermost spiral ridge. Protoconch of about 1.31.5 smooth whorls. Teleoconch sculptured with heavy, flattopped spiral ridges, 3 on penultimate whorl, 611 on last whorl; intermediate cords present between main ridges, especially on last whorl, with one between main ridges on upper part of whorl and, usually, 3 between upper and lower basal ridges; weak spiral lines and threads also present; spiral sculpture crossed by much finer collabral growth lines; base convex, subangled by lower basal ridge; umbilicus wide, rimmed by lower basal spiral ridge and with 1 or 2 ridges within. Aperture broadly ovate; peristome moderately thickened in adults; outer lip prosocline. Colour: shell opaque to subtranslucent; periostracum thin to moderate, yellowwhite to brown. One or two varices typically present, represented by rather irregular lines or breaks.
Dimensions. See
Table 28
for dimensions of
holotype
and Appendix,
Table 29
, for summary shell dimensions and whorl counts.
TABLE 28
. Dimensions of holotype of
Gabbia carinata
.
Length |
Width |
Aperture length |
Aperture width |
Length of last whorl |
Number of whorls |
Holotype |
3.46 |
3.03 |
1.74 |
1.58 |
2.67 |
4.35 |
Operculum (
Fig. 32O,P
) typical of genus. Ovate, yellowishwhite (unless stained), slightly to moderately concave, concentric growth ridges distinct; inner surface sculptured with low, concentric ridges.
Radula (Appendix
Table 30
;
Fig. 37F,G
) typical of genus. Central teeth with 35 cusps on either side of median cusp; median cusp about 1.31.4 longer than adjacent cusps, base about twice as wide, initially parallelsided to slightly tapering, distally tapering to blunt to sharp point. Face of central tooth with 23 pairs of cusps parallel to lateral margin, inner pair much larger than others, about half total height of tooth. Lateral margins straight to slightly concave; at about 5060º, basal tongue short, rounded. Lateral teeth with cusp formula 34 + 1 + 46; cutting edge about third length of lateral part of tooth; median cusp up to about twice as long as adjacent cusps, broad, parallelsided to slightly tapering, with rounded end; upper edge of lateral part of tooth at about 5060º to cutting edge, lateral edge straight. Inner marginal teeth 2125 cusps, outer marginal teeth long and very slender with expanded bases, with 59 cusps.
Headfoot with unpigmented foot, snout pale grey, tentacles with central pale grey stripe. Mantle roof unpigmented over rectum/kidney – remainder with black with large white blotches.
Anatomy. Gill with apices at about quarter of width from right; 5258 filaments (n=2). Osphradium opposite middle of gill. Penis and accessory lobe shorter than penial lobe, distal end of accessory lobe lacking swelling or distinct sucker; accessory gland moderate to short. Pallial oviduct (
Fig. 34D
) similar to
G. vertiginosa
but with relatively shorter albumen gland; bursa copulatrix narrow, extends to posterior pallial wall (AMS C.326793, AMS C.327883).
Distribution (
Fig. 39
) and habitat. Coastal plains of the
Gulf
of Capentaria and the eastern base of Cape
York
. In billabongs and pools on mud, although often associated with macrophytes and algae.
FIGURE 39.
Distribution of
Gabbia carinata
.
Remarks
This species is very distinctive amongst the Australian fauna with its trochiform shell with an open umbilicus and strong spiral ridges. However,
Mysorella costigera
has a very similar shell to
G. carinata
but differs in being much larger (about twice as large), in having a very heavy operculum, in the axial sculpture being heavier and sharper, especially on the base, and in the edge of the outer lip being very slightly reflected in adults (simple in
G. carinata
).
M. costigera
and has been described anatomically (from
India
) by
Seshaiya (1930)
. The central teeth of the radula reportedly have central teeth with only a single pair of basal cusps (
Annandale, 1920
), although
Seshaiya (1930)
noted 13 pairs and
Starmühlner (1974)
3 pairs, although the 2
nd
and 3
rd
pairs are small.
Mysorella costigera
is the
type
species of
Mysorella
GodwinAusten, 1919
. Its anatomy, as described by
Seshaiya (1930)
, closely resembles that of
Gabbia
. No mention of a seminal receptacle is made in the description of the female reproductive system and it was probably overlooked as this structure is present on the outer side of the middle of the albumen gland (opposite the entry point of the coiled renal oviduct) in
G. carinata
. Similarly, the bursa copulatrix is not recognised as such but is clearly present as the nonglandular arm of the Vshaped lumen (
Seshaiya, 1930
, textfig. 27). However, this was open to the oviduct lumen along most of its length rather than having a small anterior opening. This configuration is similar to that seen in submature specimens of
G. carinata
but differs from the bursa seen in mature specimens, which is closed off from the ventral channel for most of its length. Thus it is likely that the female specimens examined by
Seshaiya (1930)
were not fully mature, which is also probably the reason that a seminal receptacle was not reported. Given the gradation of spiral sculpture with other shell sculptural patterns, and the lack of any obvious anatomical differences reported for
Mysorella
[on the assumption that the female system described by
Seshaiya (1930)
was submature], the recognition of a distinct subfamily
Mysorellinae (
Annandale, 1920
)
for
Mysorella
, or even a distinct genus, is questionable on the available evidence. Thus, pending a detailed assessment of the relationships of the group,
Mysorella
is tentatively regarded here as a synonym of
Gabbia
.
Pseudovivipara
Annandale, 1918
and
Parafossarulus
Annandale, 1924
are the only other Asian bithyniid genusgroup name based on species that have spiral ridges on the shell. However, both these taxa, which are probably synonyms (Ponder, pers. observ.), have a larger, tallspired, nonumbilicate shell. They also differ from most other bithyniid genera in having the basal cusps of the central teeth aligned horizontally, and in a number of anatomical differences.