On the occurrence of Alloteuthis subulata in the Eastern Ionian Sea and its distinction from the sympatric Alloteuthis media

TitleOn the occurrence of Alloteuthis subulata in the Eastern Ionian Sea and its distinction from the sympatric Alloteuthis media
Publication TypeJournal Article
Year of Publication2012
AuthorsLefkaditou, E, Tsigenopoulos CS, Alidromiti C, Haralabous J
JournalJournal of Biological Research
Volume17
Pages169-175
KeywordsAlloteuthis media, Alloteuthis subulata, COI sequences, discriminant analysis, Mediterranean Sea, taxonomy
Abstract

Despite the efforts made during the last decade, the systematics of the sympatric species Alloteuthis media and Alloteuthis subulata still remains confused and the distribution of the two species in the Mediterranean Sea doubtful. The 9 male specimens identified as Alloteuthis subulata in July-August 2008, represent the first finding of this species among samples of the “International Bottom Trawl Survey in the Mediterranean” (MEDITS), which is repeatedly carried out in the eastern Ionian Sea since 1994. Morphometric data and tissue samples for mo-lecular analysis were collected from these specimens, as well as, from male and female specimens assigned to A. media from the same and near-by sampling stations. As the longer tale is the most evident characteristic to distinguish at least adult male specimen of the two species, the length of the anterior part of the mantle (from fin’s edge to mantle opening) was used as the reference length upon which indices of different body dimensions were calculated. Genetic analyses using mitochondrial DNA cytochrome oxidase I (COI) gene sequences confirmed species allocation for all individuals assigned to A. subulata, whereas for A. media samples, one female and an unsexed juvenile seemed to carry the A. subulata COI haplotype. Discriminant function analysis (DFA) of morphometric data suggested that length of arms, tentacles and tentacle clubs, all relatively smaller in A. subulata, constitute important variables allowing the distinction of the two species. However, further genetic and morphometric analyses on a larger sample covering the whole size range for both species and sexes, are needed to confirm as decisive diagnostic the value of the above mentioned characters.

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