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
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.