Macropipus arcuatus Leach, 1814
Synonyms: Portunus rondeletii Risso, 1816; P. longipes Rathke, 1837
Common names: Bulg: Rak plubet; Rom: Crabul rosu; Russ: Krab-plavunets; Turk: Calpara; Ukr: Krab-plavunets'
Taxonomic descriptions: Front not produced into teeth; anterolateral margin of the carapace with 4 unequal teeth; the third small, hardly visible. Flagellum of antenna about 2.5 times longer than eye. Chelipeds bigger with 2-3 ridges of male, smaller and smooth to female. Carpus with a strong posterio-superior spine. Fingers with little teeth (2-3); small terminal teeth. Dactylus of the fifth pereiopods like a lance, consolidated with a longitudinal ridge. Female with larger abdomen to base than male, could not cover the eggs completely. Size: lengths -18 mm; width - 22 mm. Colour: red purple for specimens from fields with Phyllophora.
Black Sea Regional level:
Subregion level: VU
Habitats type, Critical habitats, Limiting factors: Iliophilic species, to depth of 30-70 m; favourite biotop: very deep covered by Phyllophora oozy sea grounds. Reduction of Phyllophora fields, which were a favourite biota for this crab.
Biology: Species with a high prolificity (up to 3 thousand eggs); reproduction begins in spring; the eggs are yellow lying in the shape of cluster with 3-4 eggs into a verticillum.
Population trends: In the past abundant in Phyllophora fields and on the entire Romanian littoral (hundred ind/m2). In the last 20 years species has become very rare.
Threats: Hypoxic conditions on the shelf.
Conservation measures taken: None.
Conservation measures proposed: Mitigation of negative environmental impacts.
Compiled by: C. Dumitrache