Development of the hectocotylus in Illex coindetii (Verany, 1837) (Cephalopoda: Ommastrephidae)

Abstract

Species of the genus Ilex (Family Ommastrephidae) are distinguished morphologically mainly based on differences in the hectocotylus, the modified arm that males of many cephalopod species use to transfer spermatophores to females during mating We examined the developmental details of the hectocotylus in Illex coindetii, the species of Illex with the most highly modified hectocotylized arm, to determine whether it has an ontogeny that passes through stages that are similar to the less modified hectocotyli of sympatric I. illecebrosus and I. oxygonius The development of modifications of one of the ventral arms is essentially synchronous on all portions. The hectocotylus of I. coindetii is therefore morphologically distinctive even at early maturity stages, and therefore should not be easily confused with that of its sympatric congeners.