Insight in some aspects of the reproductive biology, morphometry and age of Chtenopteryx sicula (Cephalopoda: Chtenopterygidae) in the Adriatic Sea

Abstract

      The first record of the deep-sea species Chtenopteryx sicula is reported from the Adriatic Sea. A total of six specimens of this rare species were caught, with bottom trawl and pelagic trawl nets, in the scope of the Deep Sea Research of the bathyal fauna in the South Adriatic Pit in 2008 and 2010. Specimens were caught at depths down to 1200 m, therefore making it the deepest and northernmost finding of this species in the Mediterranean Sea. The dorsal mantle lengths of analyzed specimens ranged between 21 and 60 mm. Only in females, a visceral photophore on the ventral side of the inc sac was detected. Some new information on morphometric body and beak features was given in the paper, including the description of beak pigmentation. A number of increments in statoliths revealed that individuals were between three and five months old. A positive linear correlation between the length of statoliths and number of increments/age in days was detected. Macroscopic and histological samples of gonads proved that one specimen was sexually mature (August), four specimens were in stages of sexual maturation (May and August) and two were immature (March). The results indicated that the maturation process of the species in the South Adriatic Sea starts in spring and the full sexual maturity is reached during summer.