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PRELIMINARY
REVIEW OF THE POLYPLACOPHORA (MOLLUSCA) FROM THE SAMOAN
ARCHIPELAGO
The
Samoa Islands are comprised of two larger and a couple of
smaller remote volcanic Islands in the tropical South Pacific (between
13° 26‘ S - 14° 22‘ S and 172° 47‘ W - 169° 25‘ W).
The islands show a spectacular coastline with a variety of
different habitat types such as
lava cliffs, roaring blowholes, wave eroded arches, tide
pools, bays, coves with sandy beaches, reefs and shallow lagoons.
Accordingly, there is a fascinating diversity of the molluscan
fauna, already reaching about 810 shallow water species. The
Polyplacophora, however, still are poorly known and just 6
species have been recorded from Samoa so far. Within the
framework of a comprehensive inventory the present study gives a
brief revision of what is known about Samoan chitons and reports
10 species for the first time for Samoa.
The following species have been examined from Samoa: Parachiton acuminatus, Parachiton puppis, Callochiton bayeri,
Callochiton sp., Callistochiton granifer, Chiton discolor,
Chiton subassimilis, Acanthopleura gemmata, Tonicia lamellosa,
Tonicia sp., Onithochiton erythraeus, Cryptoplax elioti,
Cryptoplax larvaeformis, Acanthochitona aff. achates, Plaxiphora
cf. obscurella . Of them only Cryptoplax elioti and Callochiton
bayeri have “Samoa” as their type locality, and Callochiton sp. is being described as a new species currently. Some
taxonomical questions still are open and additional material is
necessary to resolve them in detail, e.g. to confirm the
presence of problematic species like O.
erythraeus.
So far, both Samoan Callochiton
species are not known from any other Islands, thus they may be
endemic to the Samoan archipelago. All other Samoan chiton
species were already reported from other regions, too, and the
available material shows, that the Samoan fauna has strong
influences of the New Caledonian region. Remarkably, members of
the genus Ischnochiton
are still missing from Samoa while occurring in most other
regions of the South Pacific. Collectings in greater depths will
surely yield additional data and may allow more significant
conclusions on the biogeography of Samoan Polyplacophora. |
