Sexual dimorphism in the shrimp genus Atyaephyra De Brito, 1867 (Caridea: Atyidae): the case study of Atyaephyra thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012

We describe the sexual dimorphism in the genus Atyaephyra de Brito Capello, 1867 (family Atyidae De Haan, 1849) through the example of A. thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012 as a contribution to the ongoing effort to describe the morphological variability in the genus. Individuals of A. thyamisensis were collected from Thyamis River (Epirus, northwestern Greece) over a period of five years. Selected characters were examined on the basis of already known differences recorded from the literature and from direct observations in order to detect possible intersexual morphological differences in this species. A total of 42 somatometric distances and 14 meristic characters were measured. The morphological comparison as well as the statistical analysis showed a clear separation between the two sexes and between non-ovigerous and ovigerous females. Besides the first and second pair of pleopods, sex-related differences were found between the third and fourth pair of pereiopods, rostrum, carapace, antennules, and chelae, whereas differences between the non-ovigerous and ovigerous females were most obvious in the abdominal segments. Also discussed are the key sexual morphological characters that can aid in distinguishing the species of Atyaephyra.