petasma

petasma

[pə′taz·mə]
(invertebrate zoology)
A modified endopodite of the first abdominal appendage in a male decapod crustacean.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
It is a dioecious species and exhibits sexual dimorphism with characteristic secondary sexual structures ([male]: petasma, [female]: thelycum).
[39.] Haran N, Mallo J, Fenucci J (2004) Density influence on growth and development of the petasma in juvenile shrimps Pleocticus muelleri (Decapoda, Penaeoidea).
Efecto de la densidad sobre el crecimiento y el desarrollo del petasma en langostinos juveniles Pleoticus muelleri (Decapoda, Penaeoidea).
et al., 1963; Nobel, 1964; James, 1968; Ameer-Hamsa, 1973; Zou and Fingerman, 2000; Benetti and Negreiros-Fransozo,2004), periopods (Nickerson and Grey Jr., 1967), petasma (Sivalingam and Rao, 1968) and the abdomen form (Young, 1933; Mantelatto et al.,2003; Hugo and Michel, 2005; Gregati andNegreiros- Fransozo, 2009).
In the western Atlantic Ocean, Perez-Farfante (1969, 1970, 1971a) described diagnostic characters of the genus Farfantepenaeus that allowed identification of individuals in the range of 8-20 mm CL (carapace length) on the basis of the following morphological features: 1) changes in the structure of the petasma and thelycum; 2) absence or presence of distomarginal spines in the ventral costa of the petasma; 3) the ratio between the keel height and the sulcus width of the sixth abdominal somite; 4) the shape and position of the rostrum with respect to the segments and flagellum of the antennule; and 5) the ratio between rostrum length (RL) and carapace length (RL/CL).
The sex of each specimen was determined by the presence of the thelycum and petasma, for females and males respectively.
Sex was determined by the presence of the petasma for males or the thelycum for females (Ohtomi et al.