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Nematocysts and Taxonomy in Laomedea, Gonothyraea and Obelia (Hydrozoa, Campanulariidae)
Author(s) -
ÖSTMAN CARINA
Publication year - 1982
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1111/j.1463-6409.1982.tb00536.x
Subject(s) - cnidocyte , nematocyst , biology , taxonomy (biology) , hydrozoa , cnidaria , zoology , scyphozoa , lernaean hydra , coelenterata , botany , ecology , coral , microbiology and biotechnology
The cnidoms of Laomedea flexuosa, Gonothyraea loveni, Obelia geniculata, O. longissima and O. dichotoma were studied by light and scanning electron microscopy to find out whether the nematocysts could be used as taxonomic characters. Three b‐rhabdoid heteroneme nematocysts (microbasic b‐mastigophore) and three isorhizous haploneme nematocysts (atrichous isorhiza) were distinguished. A small b‐rhabdoid nematocyst with spindle‐shaped capsule occurred in all the species examined. In the polyp and planula of G. loveni , and the planula of L. flexuosa it was the only nematocyst present. Specific for L. flexuosa was a b‐rhabdoid with curved capsule. In the polyp and newly‐liberated medusa of O. longissima another b‐rhabdoid appeared with bean‐shaped capsule and markedly long spines at the distal tube. The polyp and newly‐liberated medusa of O. dichotoma were characterized by two different isorhizas. A special type of isorhiza occurred in the polyp of O. geniculata . The curved capsules of the different isorhizas varied somewhat in shape and size. Differences in nematocyst structure and occurrence are presumed to provide characters for taxonomy. Thus, O. dichotoma and O. Iongissima are regarded as separate species due to their distinctly different nematocysts, in conjunction with other morphological and ecological differences.