Page 1 - Chitons_Mollusca_DELL_ANGELO_1998

Giornale di Geologia, ser. 3", vol. 60, 1998, pp. 235-252, Bolognn

Chitons (Mollusca, Polyplacophora) collected
during cruise CS96 in tfie Strait of Sicily 1

BRUNO DELL'ANGELO, CLAUDIO LoMBARDI an d MARCO T AVI ANI
Bruno D<li'Anft'IO- Via Mugcl/e.rr 66D, 1-59100 Prato.
Claudio Lombardi- Via Matreotri 9. 1-40062 Molinella (Bologna).
Marco Taviani -lstitu/o di Geologia Marina, C.N.R., Via Gabelli 101, 1- 40/29 Bologna.

Summary As many as 17 species of chitons (Mollusca, Polyplacophora) have been collected during
cruise CS96 in the Strait of Sicily. Most materia! is represented by loose pia t es found within
coarse-grained skelelal sedimenls which typically drape slarved areas of banks and shoals
down lo ca. 110 m of depth. While most materia! perlains lo Recenl assemblages, two
subfossil plales of Hanleya nagelfar are considered as probably belonging to glacial Pleistoce-
ne deep-sea coral assemblages. The high number of chilons collecled clearly reflecls lhe
existence of many differenl hard-bottom habilats in the study-area.
Key words: Polyplacophora, Mollusca, Quatcrnary. Strait of Sicily

Introduction
Chitons are primitive shelled benthic mol- (Tab. l) and the present contribution re-
luscs belonging to the class Polyplacophora, ports upon their taxonomic, ecologie and pa-
known since the Early Paleozoic and today Ieobiogeographic aspects.
represented by more than 800 species. Mem-
bers of this class are exclusively marine and
distributed from supratidal to abyssal
depths, typically associated to hard substrata Taxonomy
(e.g., Squires and Goedert, 1995). Modero
chitons secrete a Sr-rich aragonitic shell We have identified 17 taxa at species leve!
(Milliman, 1974) consisting of eight plates (Tab. 2). With only one exception (Hanleya
kept together by a chitinous girdle that gets nagelfar, probably a glacial Pleistocene fos-
easily loose post-mortem because of the dis- si!), ali taxa belong to species typical of the
integration of binding non-mineralized tis- Recent Mediterranean fauna.
sues. Thus, loose chiton plates may contri-
bute in forming biogenic skeletal sediments,
although they are quantitatively scarce and Class POL YPLACOPHORA Gray 1821
only occasionally recorded in the literature Order NEOLORICATA Bergenhayn 1955
as a minor constituent (Paleozoic: Lang et Suborder LEPIDOPLEURINA Thiele 1910
al., 1982; Recent: Wilson, 1979, among ot- Superfamily LEPIDOPLEUROIDEA Del-
hers). Possible exceptions are skeletal as- l'Angelo and Palazzi 1991
semblages enriched in chiton-plates known Family LEPIDOPLEURIDAE Pilsbry 1892
from early Pliocene and early Pleistocene Genus Lepidopleurus Rissa 1826
shallow-water deposits of Tuscany (Laghi, Subgenus Lepidopleurus s.s.
1984; Dell'Angelo and Forli, 1995).
Living individuals and loose plates of chi- Lepidopleurus (Lepidopleurus) cajetanus
tons have been found in many CS96 stations (Pou, 1791) Pl. l, Fig. 8

1 Scienlific results of Cruise CS96 in lhe Slrail of Sicily.

235