Revision of South African Caecidae (Mollusca: Gastropoda)
Author
Vannozzi, Angelo
Via M. L. Longo, 8, I 00151 Rome, Italy;
ang.vannozzi@gmail.com
Author
Pizzini, Mauro
Author
Raines, Bret
P. O. Box 5124, Alamogordo, New Mexico 88311, U. S. A.;
rainesbk@yahoo.com
text
African Invertebrates
2015
2015-05-13
56
1
99
99
http://www.bioone.org/doi/10.5733/afin.056.0109
journal article
10.5733/afin.056.0109
2305-2562
7661863
Caecum inhacaense
Albano & Pizzini, 2011
Figs 12A–C
,
13
,
22K
,
23K
,
24G
,
26A, B
Caecum inhacaense
:
Albano & Pizzini 2011: 5
, 6, fig. 3A–C, E.
Type locality:
MOZAMBIQUE
: Ilha de Inhaca, Barreira Vermelha.
Type material examined:
MOZAMBIQUE
:
holotype
(
MZB 15000
)
.
Material
examined:
SOUTH AFRICA
:
Eastern Cape
: 10 sh,
Mzamba
, near
Natal
border,
vii.1976
(
JPM 2119
);
1 lv
,
Mtentu R. Mouth
,
iv.1982
(
JPM 2414
)
;
KwaZulu-Natal
:
1 sh,
Aliwal Shoal
, off
Umkomaas area
, -
27 m
, SCUBA,
i.1988
(
JPM
)
;
2 sh (1 juv),
Stn ZO
4, off
Cape
St. Lucia
(
28°31.8'S
32°26.9'E
), -
76–80 m
, coarse sand with mud, dredged
R.V. Meiring Naudé
, NMDP,
12.vi.1988
(
NMSA
W9665
)
.
Doubtful:
SOUTH AFRICA
:
Western Cape
: 1 sh, Knysna, Gericke Point, Sedgefield (
NMSA
W9679
)
;
Eastern Cape
: 1 sh,
Algoa Bay
,
St. Croix
I.
,
East
, -
50–60 ft
, coarse sand, dived
A. Connell
, don.
C.S.I.R. Water Res.
1977 (
NMSA
A6770
)
;
1 sh,
Mzamba
, beachdrift, leg.
R. Kilburn
&
D. Herbert
12–
30.5.1986
(
NMSA
W9664
)
.
Comparative material examined:
C. incisum
sp. n.
Fig. 12.
Caecum inhacaense
Albano & Pizzini, 2011
, South Africa, Aliwal Shoal, off Umkomaas area (JPM) — (A) right side, (B) ventral side, (C) microsculpture. Scale bar = 1 mm (A, B); 250 µm (C).
Original description:
“Tube cylindrical, smooth, crossed only by fine growth striation. Septum mucronate, turned to right side by about 30° and protruding over the cutting plane. Mucro has the form of a small flattened ball, almost obsolete in juvenile specimens. Dorsal margin of mucro strongly convex, while its ventral margin slightly S-shaped and inflated near the cutting plane. Aperture circular, weakly ringed and slightly contracted. Juveniles have more slender shell, and aperture lip thin and fragile. Colour whitish. Operculum and soft parts morphology unknown.
Holotype
dimensions: length
1.4 mm
, diameter
0.3 mm
.”
Additional description: Tube cylindrical, colourless, whitish in beached specimens, the last portion bent toward the ventral side. No sculpture. Aperture slightly flaring and oblique. Surface with only oblique growth lines. Septum opaque, dome-shaped, variably protruding. Mucro illdefined, placed on the right side, typically higher than the septum, dorsally protruding with a resulting concave outline just above the cutting plane. Macula white, small, roundish to chevron-shaped, located in the middle of the ventral side of the tube, slightly displaced toward the left side (
Fig. 24G
). Periostracum light brown, somewhat glossy, persistent.
Length:
1.2–1.6 mm
.
Distribution: Originally described from south of
Mozambique
, its distribution is herein extended to the eastern coast of
South Africa
up to the Mtentu River (
Fig. 13
). Its occurrence on the southern coast needs confirmation.
Remarks:
Caecum inhacaense
resembles the sympatric
C. incisum
sp. n.
as regards to the general proportions, but it can be distinguished by the presence of a white macula, the lack of incised collabral grooves, the presence of a slight apertural swelling and the mucro that forms a lower angle with respect to the ventral-dorsal direction.
Caecum inhacaense
is a rather elusive species due to the lack of striking characters. A careful examination of South African specimens revealed that the bending of the last quarter of the tube and the shape of the mucro are useful characters. In particular, the mucro is neither nail- nor ear-like as in other species with similar appearance, but has a convex outline, shaped like a flattened ball that protrudes dorsally, leaving a concave region just above the cutting plane. Also the presence of a small, white macula is a useful character.