Diagnostic Value of the Thelycum in Euphausiids, I. Mediterranean Species (First note)

Abstract

DIAGNOSTIC VALUE OF THE THELYCUM IN EUPHAUSIIDS, I. MEDITERRANEAN SPECIES (First note) BY G. COSTANZO and L. GUGLIELMO Institute of Hydrobiology, University of Messina, Italy The existence in Euphausiacea of a copulatory female organ, the thelycum or spermatheca, was mentioned for the first time by Claus in 1863. Since then other authors (Zimmer, 1913; Raab, 1913, 1914; Ruud, 1932; Bargmann, 1937) gave more detailed descriptions from a morphological and structural point of view. Only Einarsson (1942) attributed a fundamental importance to the spermatheca in the systematics of euphausiids, similar to that formerly given by other authors to the petasma of