Studying
the Chiton Fauna of the Moluccas (Indonesia): preliminary
results
The
first chiton species from the Moluccas was described by Rumphius
in 1705. The species he described was probably Acanthopleura
spinosa (Bruguière, 1792), the largest species living in
the Moluccas.
The chiton fauna of the Moluccas or Indonesia was greatly
neglected until Nierstrasz wrote his major work on chitons in
1905. Based on about 350 specimens collected in shallow and deep
water by the Siboga expedition, he recorded 36 species of which
25 were described as new. Many of these species
originated from the Moluccas. After Nierstrasz no substantial
studies on Indonesian chitons were made.
During three visits (1989, 1990 and 1997) to the central
Moluccas a large collection (ca. 2500 specimens) of shallow
water chitons was gathered. This material consists of
about 34 species of which several remain undescribed or
were not previously recorded from Indonesia or the Moluccas.
Among the species which were new for the Indonesian and/or the
Moluccan fauna were:
Callistochiton generos (Iredale & Hull, 1925), Ischnochiton
albinus Thiele, 1911, Ischnochiton winckworthi Leloup,
1936, Rhyssoplax pulcherrimus (Sowerby, 1842), Lucilina
tydemani (Nierstrasz, 1905), Acanthochitona leopoldi
(Leloup, 1933) and Cryptoplax plana Ang, 1967. Of these
species A. leopoldi and Cryptoplax plana were
hitherto only known from the type material but proved to be very
common in the Moluccas. Furthermore the latter species was found
to actively burrow in solid limestone rocks, a mode of life
previously unknown within the class Polyplacophora.
The Moluccan deep water fauna could be studied due to the fact
that the material from the French KARUBAR expedition to the Kai
and Tanimbar Islands was put to my disposition.
This material was dredged in depths between 85 and 1266 meters
and consists of 58 specimens representing 7 species. All but two
species belong to the family Leptochitonidae. Also in absolute
numbers (54 specimens) the Leptochitonidae is the most abundant
group of chitons in deep water. In shallow water this family is
only represented by Parachiton cf. acuminatus (Thiele,
1909) of which one loose valve was found.
The study of the above material is still ongoing. At this moment
several species within the Acanthochitonidae and species of the
genera Callochiton (3), Rhyssoplax (1), Plaxiphora (1) and
Onithochiton (1) defy positive identification.
When the chiton fauna (both shallow water and deep water) is
considered, the Moluccas seems to form the center of a larger
zoogeographical entity which extends from the northern part of
Australia in the south to the Philippines in the north, and from
Sumatra in the west to the Solomon Islands in the east. |
