Sexual size dimorphism in the external morphology of Potamon ibericum (Bieberstein, 1809) (Decapoda: Brachyura: Potamidae) in west of Mazandaran Province, Iran

Freshwater crabs are an important part of aquatic ecosystems and can strongly dominate benthic invertebrate biomass. The Middle East freshwater crab genus PotamonSAVIGNY 1816, is a well-known genus with a distribution ranging from the Middle East through southern Europe and the far north of Africa. Sexual dimorphism is a widespread phenomenon across the animal kingdom. This phenomenon can be affected by morphological, physiological and behavioral traits. Sexual dimorphism is an important goal in biosystematics and evolutionary studies of the animal kingdom. This study was conducted in the mountain streams of tonekabon and Abbas-Abad in the west of Mazandaran Province, north of Iran, with the purpose of examining the sexual size dimorphism in Potamon ibericum using the most important Morphometric measurements. Adult animals were randomly at 8 stations in Abbas- Abad and Tonekabon highlands from April to September 2014. Using valid keys, the samples were identified and 51 morphometric characters were measured with a caliber with a precision of 0.01. Sexual dimorphism was analyzed by one-way ANOVA and Principal Component Analysis. The results of the analysis indicate the presence of sexual dimorphism in some of the studied characters. Characteristics such as height and width of the carapace, diameter and height of the chela, abdominal length, Telson length, Telson width and abdominal segments length and width had a higher value in two sexes. Most of these characters, except for the carapace width and the height of the left chela, were larger in females than males. Sexual size dimorphism in these animals can be considered as an advantage in sex selection, mating, maintenance of eggs and defense strategies. Due to the presence of sexual dimorphism in this species, geographic analysis for both males and females should be carried out separately. So that the pattern of geographic variations among these populations can be studied as far as possible and avoided possible taxonomic errors. Freshwater crabs are an important part of aquatic ecosystems and can strongly dominate benthic invertebrate biomass.

کلیدواژه ها:

Freshwater crabs ، Potamon ibericum ، Sexual dimorphism ، Statistical analysis