Morphological variation in males of Vulcanoctopus hydrothermalis (Mollusca, Cephalopoda)

Abstract

Seventeen new specimens of Vulcanoctopus hydrothermalis were collected during the French cruise HOPE 99 between 1-21 May 1999. The animals were caught at 2631 m depth at 12°48.7′N, 103°56.43′W. Vacuums and creels in seven different submersible samplings collected the specimens. Animals ranged from 22 to 56 mm dorsal mantle length (ML). A total of 26 morphometric and 10 meristic characters were measured and counted. Indices were calculated. Arms with suckers in two rows. Each row with the same number of suckers. The sucker addition is faster in small animals than in bigger animals with a near to total cessation of addition of new suckers during the later stages of arm growth. Arm formula typically 1.2.4.3 or 2.1.4.3. Mean and range of variation of morphological characters examined are given and discussed. The absence of females suggests the existence of spatial segregation by sex. Male maturation is also discussed.