[Re-description of Syncyamus aequus, Lincoln and Hurley, 1981 (Amphipoda: Cyamidae), and ectoparasite of Stenella coeruleoalba (Meyen, 1883) and first discovery in Italian waters]. / Ridescrizione di Syncyamus aequus, Lincoln ed Hurley, 1981 (Amphipoda: Cyamidae), ectoparassita di Stenella coeruleoalba (Meyen, 1833) e prima segnalazione per le acque italiane.

ABSTRACT

Syncyamus aequus Lincoln & Hurley, 1981, an amphipod parasite reported for the first time in South African waters, is re-examined in order to clarify the taxonomic value of some morphological characters not described in detail in the original description and in the following records (Raga, 1988; Sedlak-Weinstein, 1991). Three females (two ovigerous) and six males were collected from two specimens of Stenella coeruleoalba (Meyen, 1833) stranded along the Central Thyrrenian coasts in 1988 and 1993. The amphipods fixed and stored in 70 degrees ethanol were cleared with lactophenol for examination. Drawings were made with the aid of a Leitz microscope drawing attachment. The specimens examined showed the presence of spines located on pereopods I and II, which were lacking in the original description of S. aequus. The authors had the opportunity to compare the specimens (male, female and ovigerous female) with the paratype (PEMK2g) deposited in the Natural History Museum of London. The present re-examination reveals a morphological homogeneity among the specimens collected in Italian waters, the paratype and the individuals recorded by Raga (1988), thus suggesting that they belong to the same species, having a broad geographical distribution. This is the first record of S. aequus in Italian waters.