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Morphological Variability of Pleuromamma Abdominalis (Copepoda, Calanoida, Metridinidae) Along Two Latitudinal Transects in the Eastern North Pacific Ocean
| Content Provider | Semantic Scholar |
|---|---|
| Author | Fornshell, John A. Ferrari, Frank D. |
| Copyright Year | 2010 |
| Abstract | [Adult females and males of Pleuromamma abdominalis were examined from 26 plankton samples taken at stations in the eastern North Pacific Ocean along two latitudinal gradients, 150°W between 21.55°N and 14.00°S, and 119°W between 17.09°N and 20.00°S. The species was found at all stations except three between 17.9°N and 12.6°N along 119°W. Variation within a sample was observed in the ventral attenuations [= spiniform outgrowths] of the first segment of antenna 1 of females, and specimens referable to P. abdominalis forma edentata could not be distinguished unequivocally from other females. Males with a strongly asymmetrical urosome and re-curved lateral seta on the left caudal ramus, referable to P. abdominalis forma abdominalis , were found, as were males with a quasi-symmetrical urosome and simple lateral seta on the left caudal ramus, referable to P. abdominalis forma abyssalis . Specimens of the latter form were not restricted to deep water but were present in samples taken as shallow as 200 m. Males with a slightly asymmetrical urosome, not as pronounced as that of P. abdominalis forma abdominalis , and with a simple lateral seta on the left caudal ramus, also were found. The degree of asymmetry among this third group of males was variable. There was no discernable pattern in depth or geographical distribution of either female or male morphs. Based on gradations of morphological states traditionally used to diagnose the different forms of P. abdominalis , the species appears to be variable, but the nominal forms should not be considered subspecies. Morphological variation among females and males of P. abdominalis should continue to be registered; in situations where groups of P. abdominalis can be clearly categorized, they should be denoted simply as morphs. Des femelles et des mâles adultes de Pleuromamma abdominalis ont ete examines dans 26 echantillons de plancton preleves dans la partie orientale de l'Ocean Pacifique Nord, a differentes stations situees le long de deux gradients latitudinaux, 150°W entre 21.55°N et 14.00°S, et 119°W entre 17.09°N et 20.00°S. L'espece a ete trouvee dans toutes les stations sauf trois d'entre elles entre 17.9°N et 12.6°N le long du 119°W. La variation a l'interieur d'un echantillon a ete observee au niveau des proeminences ventrales [= evaginations pointues] du premier segment de l'antennule des femelles, et les specimens attribues a P. abdominalis forma edentata n'ont pu etre distingues clairement des autres femelles. Les mâles ayant un urosome fortement asymetrique et la soie laterale recourbee sur la rame caudale gauche, caracteristiques de P. abdominalis forma abdominalis , ont ete trouves, de meme que des mâles ayant un urosome quasi-symetrique et une soie laterale simple sur la rame caudale gauche, correspondant a P. abdominalis forma abyssalis . Les specimens de cette derniere forme n'ont pas ete trouves uniquement en eau profonde, mais etaient aussi presents dans des echantillons preleves a une profondeur faible de 200 m. Des mâles presentant un urosome legerement asymetrique, cependant moins que chez P. abdominalis forma abdominalis , et ayant une soie laterale simple sur la rame caudale gauche, ont aussi ete trouves. Le degre d'asymetrie dans ce troisieme groupe de mâles etait variable. Il n'y avait pas de schema evident de distribution en fonction de la profondeur ou de la geographie, des morphotypes chez les mâles comme chez les femelles. A partir des gradations d'etats morphologiques traditionnellement utilises pour la diagnose des differentes formes de P. abdominalis , l'espece apparait tres variable, mais les formes nominales ne devraient pas etre considerees comme des sous-especes. Les variations morphologiques des femelles et des mâles devraient continuer a etre enregistrees ; dans les situations ou des groupes de P. abdominalis peuvent etre clairement identifies, ces derniers devraient etre simplement notes comme des morphotypes. , Adult females and males of Pleuromamma abdominalis were examined from 26 plankton samples taken at stations in the eastern North Pacific Ocean along two latitudinal gradients, 150°W between 21.55°N and 14.00°S, and 119°W between 17.09°N and 20.00°S. The species was found at all stations except three between 17.9°N and 12.6°N along 119°W. Variation within a sample was observed in the ventral attenuations [= spiniform outgrowths] of the first segment of antenna 1 of females, and specimens referable to P. abdominalis forma edentata could not be distinguished unequivocally from other females. Males with a strongly asymmetrical urosome and re-curved lateral seta on the left caudal ramus, referable to P. abdominalis forma abdominalis , were found, as were males with a quasi-symmetrical urosome and simple lateral seta on the left caudal ramus, referable to P. abdominalis forma abyssalis . Specimens of the latter form were not restricted to deep water but were present in samples taken as shallow as 200 m. Males with a slightly asymmetrical urosome, not as pronounced as that of P. abdominalis forma abdominalis , and with a simple lateral seta on the left caudal ramus, also were found. The degree of asymmetry among this third group of males was variable. There was no discernable pattern in depth or geographical distribution of either female or male morphs. Based on gradations of morphological states traditionally used to diagnose the different forms of P. abdominalis , the species appears to be variable, but the nominal forms should not be considered subspecies. Morphological variation among females and males of P. abdominalis should continue to be registered; in situations where groups of P. abdominalis can be clearly categorized, they should be denoted simply as morphs. Des femelles et des mâles adultes de Pleuromamma abdominalis ont ete examines dans 26 echantillons de plancton preleves dans la partie orientale de l'Ocean Pacifique Nord, a differentes stations situees le long de deux gradients latitudinaux, 150°W entre 21.55°N et 14.00°S, et 119°W entre 17.09°N et 20.00°S. L'espece a ete trouvee dans toutes les stations sauf trois d'entre elles entre 17.9°N et 12.6°N le long du 119°W. La variation a l'interieur d'un echantillon a ete observee au niveau des proeminences ventrales [= evaginations pointues] du premier segment de l'antennule des femelles, et les specimens attribues a P. abdominalis forma edentata n'ont pu etre distingues clairement des autres femelles. Les mâles ayant un urosome fortement asymetrique et la soie laterale recourbee sur la rame caudale gauche, caracteristiques de P. abdominalis forma abdominalis , ont ete trouves, de meme que des mâles ayant un urosome quasi-symetrique et une soie laterale simple sur la rame caudale gauche, correspondant a P. abdominalis forma abyssalis . Les specimens de cette derniere forme n'ont pas ete trouves uniquement en eau profonde, mais etaient aussi presents dans des echantillons preleves a une profondeur faible de 200 m. Des mâles presentant un urosome legerement asymetrique, cependant moins que chez P. abdominalis forma abdominalis , et ayant une soie laterale simple sur la rame caudale gauche, ont aussi ete trouves. Le degre d'asymetrie dans ce troisieme groupe de mâles etait variable. Il n'y avait pas de schema evident de distribution en fonction de la profondeur ou de la geographie, des morphotypes chez les mâles comme chez les femelles. A partir des gradations d'etats morphologiques traditionnellement utilises pour la diagnose des differentes formes de P. abdominalis , l'espece apparait tres variable, mais les formes nominales ne devraient pas etre considerees comme des sous-especes. Les variations morphologiques des femelles et des mâles devraient continuer a etre enregistrees ; dans les situations ou des groupes de P. abdominalis peuvent etre clairement identifies, ces derniers devraient etre simplement notes comme des morphotypes. ] |
| File Format | PDF HTM / HTML |
| DOI | 10.1163/001121610X492120 |
| Alternate Webpage(s) | https://repository.si.edu/bitstream/handle/10088/9925/iz_2010Forshell_Ferrari_P%20abdominalis.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | https://doi.org/10.1163/001121610X492120 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
