The hectocotylus and other reproductive structures of Berryteuthis magister (Teuthoidea: Gonatidae)

Publication Type:Journal Article
Year of Publication:1996
Authors:J. R. Voight
Date Published:Apr
ISBN Number:0042-3211
Accession Number:ISI:A1996UE38000002

Taxonomic studies of teuthoids have emphasized characters of the hectocotylus, a modified arm that male squids use in copulation. Although gonatid squids reportedly lack a hectocotylus, one of the arms in the fourth, or ventral, pair is reported here to be modified to form a hectocotylus in male specimens of Berryteuthis magister magister (Berry, 1913) collected in the eastern Pacific and Bering Sea. The stalks of the eighth to the seventeenth suckers from the beak are enlarged in both the dorsal and medial dorsal sucker rows. The hectocotylus may have remained undetected because the changes are comparatively subtle and affect the middle, rather than the distal, part of the arm. These factors and the small size of males in fishery trawls from the western Pacific seem more likely to explain the difference between these specimens and reports of western Pacific specimens of B. magister than does species-level separation of the populations. This hypothesis is supported by the similarity of spermatophores, sperm reservoirs, and ovarian eggs from eastern Pacific specimens reported here to those previously described from western Pacific specimens.

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