BIOMINERALIZATION
IN THE RADULA TEETH OF THE CHITON GENUS ACANTHOPLEURA
(MOLLUSCA: POLYPLACOPHORA) AND ITS SIGNIFICANCE TO SYSTEMATICS
WITHIN THIS GENUS.
The
physical structure and mechanisms of biomineralization have been
elucidated in the major lateral teeth of the chiton genus Acanthopleura
with the aid of light and scanning electron microscopy and
energy dispersive spectroscopy. Following its recent revision,
this genus currently consists of 15 species, including three
species suppressed as synonyms. Specimens representing all 18 (nominal)
species have been examined. With two exceptions, the major
laterals are typically discoid and unicuspid with only limited
interspecific variation. The teeth of A.
loochooana are also essentially discoid but have a small,
distinct distal indentation, while those of A.
rehderi possess four short rounded denticles.
Biomineralization in all species of Acanthopleura
occurs in architecturally discrete compartments and, with the
exception of A. rehderi, is consistent in all tooth regions except the cusp core,
where A. curtisiana,
A. miles, A. araucariana and A.
loochooana differ in having substantial amounts of iron. The
first three of these species were previously included in the
genus Squamopleura and
there is evidence to suggest that this genus should not have
been suppressed. The substantial difference in tooth structure
between A. rehderi,
with its four denticles and total lack of a lepidocrocite region,
and that of other members of the genus Acanthopleura
suggest that this species may be more closely aligned with Onithochiton.
The inclusion of additional characters, such as tooth
biomineralization, is strongly recommended in future studies of
chiton taxonomy. |
