World Congress of Malacology Antwerp ... - Unitas Malacologica

glandular ventral organs that have been described so far only in Acanthomeniidae. The lack of radula
enables a clear differentiation of this new genus from the other two described in the family:
Acanthomenia Thiele, 1913 and Amboherpia Handl & Salvini-Plawen, 2002, which present a
monoserial radula.
Marine bivalves shell shape stabilization and reproduction
Gil, Guacira Maria 1 ; Thomé, José Willibaldo 2 ; Gomes, Suzete Rodrigues 2 ; Troncoso, Jesús
Souza 3
1. Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga,
6681. 90619-900. Porto Alegre, Brazil,
Email: guagil_8@hotmail.com
2. Praça Don Feliciano, 39/1303. 90020-160 – Porto Alegre, Brazil,
Email: thomejwb@yahoo.com.br; suzetebio@yahoo.com.br
3. Laboratório de Ecologia e Biologia Animal, Campus Lagoa-Marcosende, Vigo, Spain,
Email: troncoso@uvigo.es
Marine bivalves are important as food and economic resources throughout the entire Brazilian
seaboard. Usually, they are collected without any previous studies about their biological cycle. When
available, resources needed for the execution of these studies are too great, and the result applies to
only one species, besides that they are not easily comprehended by those who effectively explore the
resource. The complex techniques used on the biological investigations limit the generated
knowledge for the specialists and do not contribute for a better resource management. The
articulation between shell morphological analysis and the reproductive process are presented in this
work. The study was developed with five marine bivalve species of the genus Donax (Linné, 1758)
collected on southern and northeastern beaches of Brazil and southern and northwestern beaches of
Spain. The results demonstrate that, for each species, there is a length in which the shell shape
stabilization occurs, allowing the proposition of a Shape Stabilization Indicator (Indicador de
Estabilização da Forma – IEF). It was verified that the shell shape stabilization length is directly
associated to the beginning of the sexual maturing process, also allowing the proposition of IEF as an
indicator of the beginning of the bivalves’ reproductive process. For this genus, the simple
determination of ratio between three linear shell measurements is enough to obtain an average length
indicator of the beginning of sexual maturing. This methodology does not require sophisticated
equipments, long collection periods or complex laboratory analysis. Besides, the sacrifice of dozens
of animals is not necessary in order to infer the beginning of the analyzed species’ reproductive
process. The utilization of IEF for other bivalve species will allow an easy determination of minimum
capture length, which, if respected, will contribute to the maintenance of the populations’ natural
equilibrium, allowing the animals to reproduce before collection.
Sperm morphology in three marine gastropods from South Western Atlantic Ocean
(Caenogastropoda): Systematic importance
Giménez, J. 1 ; Arrighetti, F. 1 ; Teso, S. 1 ; Zabala, S. 1 ; Hermida,G. 2 ;Penchaszadeh, P. 1
1. Laboratorio de Invertebrados, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos
Aires, Argentina. CONICET y Museo Argentino de Ciencias Naturales, Av. Angel Gallardo 470,
1405 Buenos Aires, Argentina,
Email: jgimenez@bg.fcen.uba.ar
2. Laboratorio de Histología Animal, Facultad de Ciencias Exactas y Naturales, Universidad de
Buenos Aires, Argentina
The testis from Caenogastropods typically produces two types of spermatozoa, eusperm and
parasperm. The structures of both morphological forms of sperm contribute to understand the
reproductive biology and also have been useful to elucidate taxonomic and phylogenetic relationships
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