Another new species of Cypraeidae from Madagascar

(Mollusca: Gastropoda, Cypraeidae)

Cribrarula pellisserpentis sp. nov.

Description:

Shape and structure: Greatly inflated, oval. The margins are callous on both sides, slightly bent uo towards dorsum. The base is convex and callous. The spire is umbilicate, partly covered with callus. The extremities are slightly rostrate. The labral teeth are coarse and distinct, reaching towards the middle of the lip. The columellar teeth are confined to the aperture, very fine and indistinct midways, the last anterior columellar tooth is thickened. The fossula is slightly projecting, showing five small denticles, the columellar peristome is faintly ribbed.

Coloration: The ground colour of the dorsum is a uniform pale olive green, pinkish in one paratype. There is a regular but fine coast of brown netting which forms large, round lacunae, most of are overlapping. There is a wide, distinct dorsal line on the labral third of the dorsum. The ground colour of the base is plain white, changing into pink towards the margins. These, and the extremities, are densely spotted with large, indistinctly outlined dark bown spots of variable size. This spotting is reaching far towards the aperture basally, on both sides of the shell. Its density varies in the paratypes. Animal characteristics: The mantle of the partly preserved animal of the holotype is brownish, with short, unbranched papillae.


C. pellisserpentis, typical specimens

Material: three live collected specimens and twelve fresh dead shells have been studied, three specimens were available as types:
Holotype: 23,8 x 15,8 x 13,2 17 : 19 (coll. HNC Cismar)
Paratype 1: 23,0 x 15,6 x 12,2 21 : 19 (coll. Chiapponi, Lecco)
Paratype 2: 22,8 x 15,6 x 12,0 17 : 15 (subadult specimen) (coll. Blöcher, Duisburg)
Paratype 3: 24,8 x 15,1 x 13,0 20 : 19 (coll. Van Heesvelde, Gent)
Paratype 4: 25,2 x 16,3 x 13,7 19 : 19 (coll. Gabrielli, Neuss)
(length x width x height (mm), labral : columellar teeth, (depository))

Distribution and habitat: All specimens so far known were collected on beaches or by divers in depths ranging from 15 to 35 m from an area south of Tulear to Fort Dauphin, Southern Madagaskar. The species seems to inhabit reef areas with deep crevices that are difficult to access.

Ethymology: The name pellisserpentis (lat. pellis: skin, serpens: snake) refers to the narrow dorsal netting of the new species, resembling the scaly skin of a snake.

Discussion:

In the western Indian Ocean, there are several similar taxa in the genus Cribrarula, which should shortly be summarized here:

Cribrarula esontropia (Duclos 1833):
Distribution: Mauritius and La Reunion
Shape: oval, callous to narrow cylindrical (var. cribellum (Gaskoin 1849))
Labral side: rounded, callous
Columellar margin: often very callous, bent up
Marginal spotting: dense, distinct, reaching onto base
Ground colour: pale orange to pink, with two paler transverse bands

Cribrarula cribraria abaliena Lorenz 1989:
Distribution: Kenya to northern Mozambique, Natal (deep water)
Shape: oval, callous
Labral side: rounded, callous
Columellar margin: very callous, bent up
Marginal spotting: absent
Ground colour: pale orange, no conspicuous transverse banding
Dorsal netting: wide, complete, pale brown, forming large lacunae

Cribrarula cribraria ganteri Lorenz 1997:
Distribution: Sri Lanka
Shape: Elongate-cylindrical to oval, callous
Labral side: distinctly margined, slightly callous
Columellar margin: very callous
Marginal spotting: fine, often distinct on both sides, reaching onto base
Ground colour: orange to pale purple, faint darker transverse band
Dorsal netting: broad, dark, distinct, forming small lacunae

Cribrarula cribraria comma (Perry 1911) Variation A
Distribution: Somalia to Tanzania
Shape: Elongate oval to cylindrical
Labral margin: rounded, hardly callous
Columellar margin: hardly callous
Marginal spotting: rarely faint spotting along upper labral margin, absent on base and columellar side
Ground colour: pale purple, very faint transverse banding
Dorsal netting: coarse, rather dark brown, forming small lacunae

Cribrarula cribraria comma (Perry 1911) Variation B
Distribution: Mozambique to Natal, Madagascar
Shape: Oval, often callous
Labral margin: rather callous, rounded
Columellar margin: often rather callous
Marginal spotting: Often distinct spotting along the upper labral margin, some spotting rarely on columellar margin, base always unspotted.
Ground colour: Saturate purple, with distinct darker transverse band
Dorsal netting: very dark brown, forming small lacunae

The presence or absence of marginal spotting in Cribrarula is not a specific feature, as long as no other characteristics exist. It is noteworthy, however, that within a species, the character of the marginal spotting can be used to safely identify geographic populations (including subspecies).

In Madagascar and Mozambique, an interesting variation of Cribrarula cribraria comma (Perry 1811) occurs (variation B), which differs from typical specimens (variation A) by distinct spotting along the dorsal edge of the labral margin. This spotting, however, is not present along the columellar margin or on the base. This feature is a fundamental difference to the Mascarenan Cribrarula esontropia Duclos, which has lead to confusion in the past, e.g. by myself (see Lorenz 1998). The true Cribrarula esontropia (including its subspecies cribellum) seems really endemic to Mauritius and La Reunion, while all records of the species from other areas in the Indo Pacific and the Persian Gulf seem to be based upon exceptionally well spotted specimens of cribraria comma, cribraria ganteri and the new taxon described herein, Cribrarula pellisserpentis sp. nov.

Cribarula pellisserpentis sp. nov. differs from the sympatric Cribrarula cribraria comma by the presence of marginal spotting on both sides of the shell and also on base, the finer columellar teeth, the projecting fossula and the narrow, incomplete dorsal netting. These are also the differences from Cribraria esontropia (Duclos 1833), except for the dense marginal spotting, which is found in both, the new species and C. esontropia. In latter, the callus of the columellar margin reaches further towards the dorsum than in pellisserpentis sp. nov.

As already mentioned, the new species has been mistaken with C. esontropia on account of this superficial resemblance, whereas the consistent differences in dentition and fossula have been overlooked. The slightly projecting, finely denticulate fossula is a feature only found in the eastern Pacific Cribrarula cumingii (Sowerby 1832). The set of shells investigated suggests that the narrow, incomplete dorsal netting, along with the uniform greenish to pinkish ground colour (without transverse banding as seen in most other taxa of the genus), the distinct dorsal line in Cribarula pellisserpentis sp. nov. and the features of the dentition are specific characteristics that do not lie within the variation range of any other member of the genus.

Acknowledgements: Many thanks to Mr. Jo Van Heesvelde, Gent-Wondelgem, and Mr. Manfred Blöcher, Duisburg, who, independently from each other, drew my attention to the group of Cribrarulae from Madagascar. Dr. Marco Chiapponi, Lecco, and Mr. Ludwig Gabrielli, Neuss, who made their beautiful specimens of C. pellisserpentis available as paratypes.

References:

Lorenz, F. & Hubert, A. (1993): A Guide to Worldwide Cowries, Chr. Hemmen Verlag, Wiesbaden
Lorenz, F. (1997): A new species of Cribrarula cribraria from Sri Lanka (Gastropoda: Cypraeidae). Schriften zur Malakozoologie 10:1-3
Lorenz, F. (1998): Kauris von Ostafrika. Schriften zur Malakozoologie 12: 1-150