World Congress of Malacology Antwerp ... - Unitas Malacologica

Spermatozoan morphologies of some species of marine bivalves: aspects of taxonomic and
ecological relevance
Orlandi Introíni, Gisele; Recco-Pimentel Shirlei Maria
Departamento de Biologia Celular, Instituto de Biologia, Universidade Estadual de Campinas, SP,
Brazil,
Email: giseleorlandi@gmail.com
Several studies of comparative sperm morphology have been published within the Bivalvia, and
collectively these help to confirm the usefulness of sperm features for taxonomic and phylogenetic
analysis at and above the species level. It has been suggested that besides the mode of fertilization,
the sperm morphology could also be correlated with egg size and larval development. Hence, the
occurrence of different types of sperm morphology according to distinct reproductive patterns has
showed the relevance of studies that focus the comprehension of the relationships associated with
evolution, ecology and morphological sperm diversity.
Using scanning and transmission electron microscopy, the spermatozoan morphologies of marine
bivalve species from Brazil and Panama - Brachidontes darwinianus, B. solisianus, Mytella
charruana, Mytella guyanensis (Mytilidae) Isognomon bicolor, I. alatus (Isognomonidae),
Anomalocardia brasiliana and Tivela mactroides (Veneridae) - were described and compared with
those of others bivalves.
The compilation of the sperm ultra structure studies of the marine bivalves provides a plethora of
information. These studies are enough to outline a comparative study with taxonomic relevance. In
addition, the results of the present work showed evidences that there is a strong correlation between
sperm morphology and environmental conditions. Some special features of the sperm cells such as
hydrodynamic shape, presence of glycogen clusters or even length of the tail could represent an
adaptation to turbulent waters and could be responsible for reproductive advantages. Hence, the
results of the present analysis are of taxonomic relevance and could contribute to the robustness of
bivalve systematic. Besides, the study of the sperm morphology allows the comprehension of some
ecological aspects that could contribute to the successful dominance of some species.
Certainly, cell characteristics reflect an adaptation to marine environment, albeit unfortunately, just
some authors have discussed sporadically the correlation between marine dynamism and sperm
features.
A new land snail zoogeography of Turkey derived from the distribution ranges of endemic
species
Örstan, Aydın
Section of Mollusks, Carnegie Museum of Natural History 4400 Forbes Ave, Pittsburgh, PA 15213-
4080, USA,
Email: pulmonate@earthlink.net
Approximately 210 taxa of stylommatophoran land snails whose ranges do not come within 50 km of
a land border are considered to be endemic to Turkey. The Clausiliidae top the list with 67 endemic
taxa, followed by the Enidae with 40, the Hygromiidae with 38 and the Zonitidae with 28 taxa. There
are 11 genera endemic to Turkey.
The distribution ranges of the endemic taxa were mapped on a 1° latitude x 1° longitude grid.
Various indexes for endemism taken from the literature were used to analyze the distribution patterns
of the endemics.
The ranges of the endemic species cluster around three centers of endemism: (1) in the northwest
bordering the Sea of Marmara and the Black Sea; (2) in the northeast along the Black Sea; (3) in the
southwest along the Mediterranean. No family is restricted to any one center of endemism and all
three centers contain representatives of all of the four largest families.
The three centers of endemism fall on mountainous areas. Each is in a different climate zone, but
they all are in areas that receive the highest amount of precipitation in Turkey. The distribution
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