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Morphological separation of Daphnia pulex and Daphnia obtusa in North America 1
Author(s) -
Schwartz Steven S.,
Innes David J.,
Hebert Paul D. N.
Publication year - 1985
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1985.30.1.0189
Subject(s) - daphnia pulex , pulex , biology , daphnia , carapace , branchiopoda , zoology , crustacean , ecology , cladocera
Although earlier taxonomic surveys failed to reveal its presence, Daphnia obtusa is common in the midwestern United States. The species has been confused with Daphnia pulex, but may be distinguished by conventional morphological features. Females of D. obtusa are characterized by large antennular mounds and weak carapace spinulation; males distinguished from D. pulex by their short postabdominal process and lack of a postabdominal bay. Principal component analysis indicates that these features clearly discriminate between the two species. The presence of hairs on the inner lip of the carapace of females is the most reliable means of recognizing the species from D. pulex.