The text of the original descriptions of Palmadusta androyensis and P. consanguinea

Two new living species of Cypraeidae from Southern Madagascar

(Mollusca: Gastropoda: Cypraeidae)

by Manfred Blöcher & Felix Lorenz

In recent years the coastline of Madagascar has been the source of many interesting new discoveries in the field of Malacology, especially of the families Conidae and Volutidae several new species and interesting new variations have come to light. This paper describes a new Cowry from the south of the island.

Palmadusta androyensis sp. nov.

Description:

Shape and structure: Evenly oval-pyriform, depressed and callous. The base is callous and convex. The margins are rather angular, expanded and bent up towards the dorsum on both sides, framing the shell, forming depressions on either side of the anterior extremity. The spire is covered with callus (in a juvenile specimen it is small and deeply umbilicate). The extremities are blunt and short. The teeth are fine and restricted to the aperture. The first anterior columellar tooth is hardly thickened but separated from the terminal by a rather distinct gap. The anterior terminal is calloused, not forming a distinct ridge. The fossula area is steep, with four faint denticles (up to six in the paratypes). The aperture is narrow, gently curved posteriorly, not widening anteriorly.
Colouration: The dorsal ground colour is dark chestnut, eroded shells vary from yellowish to orange- brown. There are two very narrow whitish bands crossing the dorsum. These may be uninterrupted or with a zigzag-outline. The margins are brownish and separated from the dorsum by a paler zone of grey. Base and margins are densely spotted with darker. This spotting extends onto the extremities and towards the dorsum. The extremities are blotched with darker brown, but the tips and channels of the extremities are not stained (as in species of Purpuradusta). The dorsum of most specimens so far known is decorticate, but traces of dorsal pattern are not present even in relatively fresh shells retaining parts of the enamel. The animal characteristics are unknown.

Material: About twenty moderately eroded specimens, five of which are designated as types:

Holotype: 15,7 x 11,2 x 8,1 15 : 15 (coll. HNC Cismar)
Paratype 1: 16,4 x 11,1 x 8,9 16 : 15 (coll. Blöcher, Duisburg)
Paratype 2: 15,7 x 11,0 x 8,5 15 : 16 (coll. HNC Cismar)
Paratype 3: 15,3 x 10,7 x 8,2 15 : 15 (coll. Blöcher)
Paratype 4: 15,3 x 11,3 x 8,2 15 : 13 (coll. Lorenz)
(length x width x height (mm); labral : columellar teeth, depository)

Locus typicus and distribution:

Most specimens known to us were collected on the beaches between the deltas of the Mandrare and Manambovo rivers (the latter mostly dry), southwest of Fort Dauphin, Southeastern Madagaskar. Further findings were made on beaches in the Southwest of this country from about the 24th degree latitude southwards. It is probable that the range of the species covers the whole southern tip of Madagascar. The habitat is unknown but probably sublitoral, judging from the eroded state of the type specimens.

Ethymology:

The name androyensis refers to Androy, a southern region of Madagascar named after the native tribe of the Antandroy.

Discussion:

Despite being known only from dead collected specimens so far, Palmadusta androyensis sp. nov. represents a well distinguishable member of Cypraeidae whose assignment to the genus Palmadusta on account of the character of the dorsal banding must be considered provisional. It cannot be confused with any other living member of the family Cypraeidae even in an eroded state. In the genus Palmadusta, there are a few smaller species which in the following will be compared with Palmadusta androyensis sp. nov. Palmadusta ziczac (LinnÈ 1758) does show a dorsal banding somewhat resembling that of androyensis, but in latter species the banding is much narrower, there are only two instead of three bands, and the ground colour is much darker than in ziczac. Furthermore, the base of androyensis is plain white instead of orange, the columellar teeth are confined to the aperture. Palmadusta diluculum has a white base, but it shows a completely different type of banding, and is much less callous. The strong development of callus safely distinguishes androyensis from all members in the genus.


P. androyensis, typical specimens

The discovery of Palmadusta androyensis Blöcher & Lorenz 1999 in the south of Madagascar was a remarkable event in the study of the Cypraeidae, simply because none had expected that a distinctive and seemingly not too rare member of this family had escaped the attention of taxonomists. In the same area where androyensis is found, another similar, but consistently different and much rarer species has been found. As it seems to represent a sister-species occuring alongside with androyensis it shall here be described as

Palmadusta consanguinea sp. nov.

Description:

Shape and structure: Evenly oval-pyriform, depressed and callous. The base is callous and convex. The margins are rather angular, expanded and somewhat bent up towards the dorsum on both sides, framing the shell, forming depressions on either side of the anterior extremity. The spire is umbilicate, half covered with callus. The extremities are blunt and short. The teeth are fine and restricted to the aperture. The first anterior columellar tooth is hardly thickened but separated from the terminal by a rather distinct gap. The anterior terminal is calloused, forming an indistinct ridge. The fossula area is steep, with three faint denticles (two to three in the paratypes). The aperture is narrow, distinctly curved posteriorly, not widening anteriorly.
Colouration: The dorsal ground colour is saturate orange-brown. There are three narrow bands crossing the dorsum. The two outer ones are dark brown, interrupted by white dots, the middle band is somewhat narrower and also brown but not interrupted with paler colour. The margins are pale brownish, not separated from the dorsum by a paler zone. Base and margins are spotted with darker. This spotting extends onto the extremities and towards the dorsum. The extremities are somewhat darker brown, but not blotched. There is no secondary adult pattern even in shells retaining the enamel. The animal characteristics are unknown.

Material: About ten moderately eroded specimens are known to us, four of which are designated as types:
Holotype: 16,2 x 11,0 x 8,5 17 : 13 (coll. Naturkundemuseum Stuttgart)
Paratype 1: 15,1 x 9,6 x 7,4 17 : 13 (coll. Blöcher, Duisburg)
Paratype 2: 18,3 x 12,4 x 9,3 18 : 13 (coll. Blöcher, Duisburg)
Paratype 3: 16,2 x 10,2 x 7,7 17 : 14 (coll. Lorenz)
(length x width x height (mm); labral : columellar teeth, depository)

Locus typicus and distribution:

Same as that of androyensis.

Ethymology: The name consanginea (lat. blood-brother) gives credit to the common characters of the new species and P. androyensis against all other known Cypraeidae, and the fact that it is basically the same species...

Discussion:

Palmadusta consanguinea can only be compared to P. androyensis. It differs from this species by the paler orange-brown instead of purplish dark brown dorsal colour, by the transverse banding consisting of darker brown interrupted with white, instead of the mostly uninterrupted white banding in P. androyensis. Finally, the darker third middle- band seen in consanguinea is always absent in androyensis. These features of the dorsal colouration in our opinion justify a separation on species-level, especially due to the fact that both taxa share the geographical region without forming intermediate stages. This we can state almost with certainity - since the describing androyensis we have had the opportunity to study several hundred specimens of androyensis. Other conchological differences are the significantly more numerous labral, and less numerous columellar teeth in consanguinea, as well as a fossula region with fewer or no denticles. The aperture in this species is also somewhat more curved posteriorly. In the specimens known to us, the marginal spotting in consanguinea is less dense, and there is no paler zone separating the dorsum from the margins as in androyensis.

Literature:

Blöcher, M. & Lorenz, F. (1999): A new living species of Cypraeidae from Southern Madagaskar. Schriften zur Malakozoologie, Cismar 13
Lorenz, F. & Hubert, A. (1993): A Guide to Worldwide Cowries. Hemmen Verlag, Wiesbaden




P. consanguinea, types

Study of hundreds of specimens suggests that consanguinea represents an color variant of androyensis rather than a distinct species. Molecular data confirms the relation between androyensis and ziczac.