World Congress of Malacology Antwerp ... - Unitas Malacologica

within gastropods.The following account describes the structure and ultrastructure and the possible
systematic importance of euspermatozoa and paraspermatozoa in three species, two from the
Volutidae family Adelomelon beckii and Adelomelon ancilla, and the third one Olivancillaria
deshayesiana from the Olividae family. Specimens of A. beckii and O. deshayesiana were collected
by bottom trawling of Mar del Plata (38º20’S 57º37'W) in 35 to 40 m and 8 to 12 m water depth
respectively. A. ancilla were colected in Puerto Madryn, (42º 42’ S 65º 06’ W), by scuba diving,
between 5 and 10 m water depth.For ultraestructural studies small pieces of the testis were fixed in
2% glutaraldehyde, were embedded in Spurr´s epoxy resin and ultra-thin sections were cut and
stained with uranyl acetate and lead citrate. For light microscopy small pieces of testis were fixed in
Bouin´s solution for using several techniques as hematoxilin –eosin, and Tricrmic of Masson and
“Periodic Acid Shiff”. In these species, the testis is limited externally by a connective tissue, in
contact with the hepatopancreas. Inside of the tubule in the periphery area is possible to see different
stages of the spermatogenesis, mature sperm are in the middle of this tubules, as also in the spermatic
ducts. The euspermatozoa is characterized by: the presence of an acrosomal vesicle with apical bleb
and accessory membrane; the nucleus is long and tubular with the axoneme penetrating the nucleus;
midpiece with mitochondrial elements coiled helically around the axoneme, glycogen piece and short
en piece. In A. beckii and A. ancilla was possible to see the paraspermatozoa, vermiform, exhibiting
multiple peripheral axonemes and with scattered mitochondria and small dense vesicles.
Examination for shell surface adaptations to water management in a rock-dwelling land snail
Giokas, Sinos
Section of Animal Biology, Department of Biology, University of Patras, GR-26500, Patras, Greece,
Email: sinosg@upatras.gr
Land snails display a great diversity of shell structures subject to adaptive explanations. Ribs, which
are transverse protrusions on the shell surface, are an example. For the rock-dwelling snail Albinaria
variation of shell sculpture is attributed to water management adaptations. However, detailed
experimental tests of these hypotheses are lacking.
I examined trait conservatism and the capacity of various Albinaria species, differing in rib pattern,
to adhere and retain water on their shells, and the relation between ribbing and activation time after
aestivation. Phylogenetic signal in all traits was random. Differences in shell sculpture affect shell
weight and water adhesion but not water retention and activation time. Climatic variables have no
influence on rib patterns. Therefore, shell sculpture is not sufficient alone to explain the ability of
Albinaria to withstand adverse conditions. Thus, additional morphological, behavioural and
physiological adaptations must be considered as promising candidate traits for further studies of
divergence.
An improved method for the identification of areas of endemism using species co-occurrences
Giokas, Sinos; Sfenthourakis, Spyros
Section of Animal Biology, Department of Biology, University of Patras, GR-26500, Patras, Greece,
Email: sinosg@upatras.gr; sfendo@upatras.gr
The prerequisite for extensive geographic co-occurrence of all the species within an area of
endemism (AoE) is the core of an ongoing debate, and thus alternative approaches favor the
identification of biotic elements, which are groups of taxa whose ranges are significantly more
similar to each other than to the ranges of other taxa. In this work, we develop a simple method that
combines the notions of biotic elements and of areas of endemism. It overcomes the constraints of a
previously suggested null model based method that cannot deal with disjunctions and is strictly-grid
dependent. Fist, we use a null model approach to determine which pairs of species have a significant
degree of co-occurrence, in order to determine biotic elements. Subsequently, we use only those
76