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Chullasorn S.,Ramkhamhaeng University | Ferrari F.D.,IZ MSC | Dahms H.-U.,National Taiwan Ocean University
Helgoland Marine Research | Year: 2010

Both genders of Pseudocyclops schminkei n. sp. are described from a pearl fishery aquarium on Zamami Island, Okinawa, Japan; it is the 37th species of the genus. Pseudocyclops schminkei sp. nov. differs from other species of the magnus species group in the shape of the lobes of distal exopodal segment of the male left leg 5, and the morphology of setae on middle and distal exopodal segment of male right swimming leg 2. Aspects of the morphology of P. xiphophorus and P. bilobatus are redescribed, and an unnamed Pseudocyclops sp. from the Shedd Aquarium in Chicago, IL, is briefly noted. Females of P. schminkei sp. nov., P. xiphophorus and Pseudocyclops sp. could not be separated from each other with the small number of specimens available in this study for the former two species. © Springer-Verlag and AWI 2009.

Ivanenko V.N.,Moscow State University | Ferrari F.D.,IZ MSC | Defaye D.,French Natural History Museum | Sarradin P.-M.,French Research Institute for Exploitation of the Sea | Sarrazin J.,French Research Institute for Exploitation of the Sea
Cahiers de Biologie Marine | Year: 2011

A new species, Tisbe dahmsi sp. nov. (Crustacea, Copepoda: Harpacticoida: Tisbidae) is described from the Eiffel Tower edifice located in the Lucky Strike vent field (37°N) (Mid-Atlantic Ridge MAR, 1698 m). The samples were collected in colonization experiments (SMAC arrays) that were deployed in 1997 during the MARVEL cruise and recovered in 1998 during the PICO cruise. Other specimens were collected during the MoMARETO cruise during which a physico-chemical characterization of copepod microhabitats was done. The new species belongs to the T. gracilis group based on similarities of the spine-like inner seta on the proximal endopodal segment of the male second swimming leg, which is terminally bifurcate. Re-examination of the closest relative and shallow-water species T. gracilis revealed a number of distinctions, including differences in shape and ornamentation of this terminally bifurcate seta. Tisbe dahmsi sp. nov. is found abundantly in the in situ colonization experiments (SMAC arrays) deployed on Bathymodiolus azoricus mussel assemblages at the Eiffel Tower edifice, together with the cyclopoid copepod Hepterina confusa Ivanenko & Defaye, 2004 (Cyclopoida: Cyclopinidae), the harpacticoid copepod Smacigastes micheli Ivanenko & Defaye, 2004 (Harpacticoida: Tegastidae) and the dirivultid copepod Aphotopontius atlanteus Humes, 1996 (Siphonostomatoida: Dirivultidae). Another colonization experiment, deployed near a black smoker, exhibits a different pattern with dominance of the harpacticoid families Ameiridae and Argestidae of the Ectinosomatidae family. These colonization experiments revealed that copepods of the genus Tisbe were substantially more abundant in the trays deployed on mussel assemblages than to those in the vicinity of black smokers. Nevertheless, no clear response regarding the effect of organic enrichment on copepod abundance was observed. The type of environment where the arrays were deployed appears to have a stronger influence on copepod abundances and composition than the treatment applied within each tray. Directly on the Eiffel Tower edifice, Tisbe copepods were found within different Bathymodiolus azoricus assemblages. These assemblages were alternatively dominated (in terms of copepods) by the Dirivultidae or the Tegastidae, the former being dominant in 67% of the samples. In terms of environmental conditions, Tisbe dahmsi was found in microhabitats characterized by low temperatures (< 8.8°C) and where the estimated hydrothermal inputs vary between 0.22 and 1.38%. The relative abundance of adult Tisbidae within B. azoricus assemblages was higher at the higher temperatures as well as at the higher concentrations of sulfide and iron and at lower pH compared to the surrounding sea water. This paper is the first description of a free living representative of the family Tisbidae from deep-sea hydrothermal vents.

Ivanenko V.N.,Moscow State University | Defaye D.,French Natural History Museum | Segonzac M.,French Natural History Museum | Khripounoff A.,French Research Institute for Exploitation of the Sea | And 2 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2011

Females of the new species Exrima walteri sp. nov. were found in sediment trap samples deployed over different sites of the East Pacific Rise (13N) at 2600m depth. Four traps were deposited during the HOPE99 cruise (1999) and recovered during the AMISTAD (1999) cruise on the research vessel L'Atalante. The new species is distinguished from congeners, E. singula Humes, 1987 and E. dolichopus Humes, 1987, by the following derived characters: first somite of the urosome with 3 (one dorsal and two lateral) stout conical extensions; distal endopodal segment on the swimming leg 4 broad. In addition, many specimens of copepodids I and lecithotrophic nauplii, identified as belonging to Dirivultidae gen. sp., were found in the samples of all sediment traps. This is the first record of copepodids I and of a nauplius of dirivultids from the Pacific Ocean. Study of type and additional material collected during different Ifremer cruises at different vent sites (HERO91, EXOMAR, PHARE and MoMARETO) required synonymy of four species of Aphotopontius Humes, 1987, Stygiopontius Humes, 1987 and Rhogobius Humes, 1987. Aphotopontius rapunculus Humes and Segonzac, 1998 is transferred to the genus Rhogobius because it possesses all presumed derived attributes of this genus: last abdominal somite with lobes at sides of anal operculum; second segment of antennal endopod elongate and slender. A new study of the type material suggests that: Aphotopontius temperatus Humes, 1997 is a synonym of A. atlanteus Humes, 1996; Stygiopontius lumiger Humes, 1989 is a synonym of S. sentifer Humes, 1987 while S. bulbisetiger Humes, 1996 is a synonym of S. pectinatus Humes, 1987. Females of the three synonymized species were found to be sub-adult females at copepodid V. Leg 6 on these specimens is one seta located dorsolaterally on the posterior part of the genital somite. This position for leg 6 is unknown for copepodid V of other siphonostomatoids whose leg 6 is located ventrally at copepodid V; the dorsolateral position is presumed derived and shared by the dirivultid genera Aphotopontius Humes, 1987 and Stygiopontius Humes, 1987. A new key to the Dirivultidae genera is presented. © 2011 Marine Biological Association of the United Kingdom.

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. © 2010 BRILL.

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