Systematics and biology of the sepiolid squids of the genus Rossia Owen, 1835 in Canadian waters with a preliminary review of the genus

Mercer, M. C.(Malcolm Clarence) (1968) Systematics and biology of the sepiolid squids of the genus Rossia Owen, 1835 in Canadian waters with a preliminary review of the genus. Masters thesis, Memorial University of Newfoundland.

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Abstract

Collections comprising about 325 specimens of Rossia from the Canadian Atlantic, Pacific and Arctic are reported upon. -- The arctic-boreal R. palpebrosa, the type species, is redescribed and R. glaucopis, R. sublevis, R. hyatti, and R. papillifera are regarded as synonyms. The species is amphi-Atlantic. The boreal R. megaptera is redescribed from topotypic material and shown to be a valid species. As presently known it ranges from the Hudson Canyon to Davis Strait. R, molleri is shown to be an arctic endemic, the only such known cephalopod; a relict population was found in Hebron Fiord, Labrador. R. pacifica is the only species of the genus foiond off British Columbia; it is amphi- Pacific. Species excluded from the Canadian Atlantic fauna are R. caroli, an eastern Atlantic species, and R. tenera, a tropical-boreal species which ranges northwards only to Georges Bank. -- The subgenus (genus - some authors) Allorossia, since founded upon material (R. glaucopis) synonymous with the type species of Rossia, is left in the synonymy of Rossia. The subgenera Semirossia and Austrorossia are recognized. A total of l8 species are provisionally recognized for the genus. -- The gross morphology is briefly considered from a taxonomic aspect. Except for sucker size in some instances, indices of body proportions are of little taxonomic value. The most stable of the characters investigated are the structure of the club, funnel organ, anal papillae and palps and, particularly, the sexual characters of spermatophore and hectocotylus structure. -- Eggs ripen in small clusters and individual females spawn several times over a protracted season; ova counts ranged upwards to about 500. Females mature later and attain a larger size than the males. Feeding is principally on benthic Crustacea and small fish. A hemiurid trematode was found in the stomach and caecum of a few specimens.

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