World Congress of Malacology Antwerp ... - Unitas Malacologica

In a rather conservative approach 17 species were recognised as valid, among them three new
species. All species are endemics with a more or less restricted distribution. The three Loyalty Island
species are local endemics while the smaller northern and southern adjacent islands of New
Caledonia (Îles Belep, Île des Pins etc.) share their one or two species with the main island. The
highest diversity (eight species) is found in the southern third of Grande Terre.
On account of similarities in the female reproductive system all New Caledonian helicinids were
included into the single genus Sturanya WAGNER 1905. Despite the similarities, two subgroups were
recognised on Grande Terre that are readily distinguished by the surface sculpture of the early
postembryonic whorls. The significance of this characters is evidenced by the resulting consistent
pattern of distribution revealing a northern and a southern radiation with the latter being more diverse
and reaching further north because of a few small-sized species with a wider distribution.
The younger Loyalty Islands were clearly colonised from different sources, with one species
originating from the southern radiation on Grande Terre, while the other two species show affinities
to Vanuatu and to several north-eastern archipelagos including Vanuatu, Fiji, Tonga, and Samoa
respectively.
A comparative anatomical and ultrastructural study of the gland of Leiblein of two muricids
species with different diets
Richter, Alexandra 1,2 ; Amor, Maria Jose 3 ; Ramón, Montserrat 4 ; Dufort, Mercedes 3
1. Dipartimento di Biologia Animale e dell'Uomo, “La Sapienza” Rome University, Viale
dell'Università 32, I-00185 Roma, Italy,
2. Laboratorio de Biología Marina, Departamento de Biología, Universidad Autónoma, Madrid,
España,
Email: alexandra@acett.org
3. Universidad de Barcelona, Av. Diagonal, 645 08028 Barcelona, Spain,
Email: mamor@ub.edu, Email:mdurfort@ub.es
4. Instituto Oceanográfico de Baleares, Muelle del Poniente, s/n Apdo. 291, 07015 Palma de
Mallorca, Spain,
Email: montserrat.ramon@ba.ieo.es
Preliminary results on the ultrastructure of the gland of Leiblein of two neogastropod species of
different feeding habits, Bolinus brandaris and Coralliophila meyendorffii (Muricidae), are reported.
Under laboratory conditions, individuals of B. brandaris predate on living bivalves (Chamalea sp.),
while individuals of C. meyendorffii, which pertains to a highly modified and late muricid radiation
integrated exclusively by symbionts of anthozoans, suck on the tissue of actiniarians and scleractinian
corals. Among both species, the gland of Leiblein shows drastic differences in the anatomical
organization and in its connection to the mid-oesophagus. In B. brandaris, the gland, pale yellow in
starved, and brown and soft in fed individuals, appears as a solid organ formed by tightly adpressed
acini with high prismatic cells that is connected to the oesophagus through a duct with glandular
folds. By contrast, the gland of Leiblein of C. meyendorffii, which in fed individuals acquire the same
colour of the anthozoan host, consists in a large sac directly connected to the mid-oesophagus and
with a wide central cavity crossed by two bilateral symmetrical rows of folds hanging free from the
wall. Such organization has been described in the few coralliophilines studied to date. At the
ultrastructural level, at least two common main cell types, also present in Nucella lapillus, are
recognized in the glands of both species. One of the cell types is ciliated and has principally an
absorption function, as suggested by the dense microvilli at the apical plasma membrane. The second
type, with a smooth apical surface and a dense cytoplasm with Golgi complex and rich in
endoplasmatic reticulum, lysosomes and mitochondria, maybe is involved in pinocytosis and in the
synthesis of secretion granules. The ultrastructural similarities among the gland cells of both species
supports strongly the homology of the organ at least within Muricidae.
183