A NEW MESOCYCLOPS (COPEPODA,CYCLOPIDAE) FROM NEW CALEDONIANFRESHWATERS

BY

DANIELLE DEFAYE Muséum nationald’ Histoirenaturelle, Laboratoire de Zoologie-Arthropodes, 61, rue de Buffon, F-75005Paris, France

ABSTRACT

Anewspecies of the genus Mesocyclops (Cyclopoida,Cyclopidae) is described from New Caledonia.This is theŽ rstreport of thegenus for the copepod fauna of New Caledonia. Mesocyclops medialis n.sp.belongs to the thermocyclopoides -group.It shows a greatsimilarity to M.isabellae Dussart& Fernando,1988 (India) and with the two species M. woutersi and M. afŽ nis described byV ande V elde(1987) from Papua-New-Guinea. Some common characters with the Australian M. brooksi Pesce,De Laurentiis & Humphreys,1996 are also discussed.

RÉSUMÉ

Uneespè ce nouvelle du genre Mesocyclops (Cyclopoida,Cyclopidae) est dé crite de Nouvelle- Calédonie. C’ estla premiè re trouvaille du genre pour la faune copé podologique de Nouvelle- Calédonie. Mesocyclopsmedialis n.sp. appartient au groupe thermocyclopoides .Ilpré sente de grandesressemblances avec M.isabellae &Dussart& Fernando,1988 (Inde) et avec les deux espèces M. woutersi et M. afŽ nis décrites par V andeVelde(1987) de Papouasie-NouvelleGuiné e. Ellepré sente par ailleurs des caractè res communs avec l’ espèce australienne M. brooksi Pesce, De Laurentiis& Humphreys,1996.

INTRODUCTION

Amongthe sevenspecies offreshwater Copepodareported earlier byDussart (1984,1986) from New Caledonia, only a fewcyclopoids belonging to the genera Eucyclops, Tropocyclops , Microcyclops , and Thermocyclops havebeen identiŽ ed. Duringa samplingcampaign (undertaken as apart ofthe research programmeof the Muséum national d’Histoire naturelle, Paris, “Terrestrial biodiversity in New Caledonia”), anewspecies ofthe genus Mesocyclops has beenfound in several samples. This species is heredescribed and its putativeafŽ nities are discussed. This represents the Žrst recordof the genus Mesocyclops fromNew Caledonia.

c KoninklijkeBrill NV ,Leiden,2001 Crustaceana 74(7):647-658 ° 648 DANIELLEDEFA YE

METHODS Specimens wereexamined by light microscopy,after dissection in lactic acid orglycerol and with the dissected parts mountedin glycerol.Preparations were sealed with Eukitt (O.KindlerGmbH & Co.,Freiburg, Germany). All drawings havebeen prepared using a camera lucida onWild M20 or Leitz Diaplancompound microscopes. All specimens are depositedin the collections ofthe Muséum national d’Histoire naturelle, Paris.

Abbreviationsused: Th5, Ž fthpedigerous somite; Ur, urosomite; P1-P4: Ž rst-fourthnatatory legs; P5,Ž fthmodiŽ ed legs; Enp, endopodite; Exp, exopodite; Me, external lateral furcal seta; Te, terminal externalmostfurcal seta; Th5, pediger 5. Terminologyaccording to Dussart& Defaye(1995).

Family CYCLOPIDAE Burmeister, 1834 Mesocyclops G.O.Sars, 1914 Mesocyclopsmedialis n.sp.(Ž gs. 1-3) Materialexamined. — Holotype:female, registration number MNHN-Cp1897, on 2 slides, dissectedand mounted in glycerol and sealed with Eukitt. Allotype: male, registration number MNHN-Cp1898,on 2slides,dissected and mounted as female.Paratypes: 3 malesand 25 females preservedin ethanol, registration number MNHN-Cp1899. Typelocality: Station 90, Pouembout; “ Vallée desCormier” ; 11:30h; dam-waterreserve on the RM3,left side, GIE; 11.xii.1996;New Caledonia. Othermaterial examined: 24 other specimens, males and females from the following stations: Station32, South Province; along the road, about 2 kmfrom Madeleine falls; large, deep temporary pondwith clear water; 1.xii.1996; New Caledonia;3 .—Station54, Boghen V alley;pond on the rightof the road from Bourail to Boghen;10:15 h; 5.xii.1996; New Caledonia;4 .—Station89, Pouembout;“ Vallée desCormier” ; dam-waterreserve on theRM3, right side, 11.xii.1996, organic matterabundant; New Caledonia;4 , 1 .—Station90, Pouembout; “ Vallée desCormier” ; 11:30h; dam-water reserve on the RM3, left side, GIE; 11.xii.1996;organic matter abundant; New Caledonia;7 , 4 .—Station106, pond located in the P AFofT ango,along the road from Pouemboutto T ouho;altitude 300 m; 13.xii.1996; New Caledonia;1 . Alltype material has been deposited in the collections of the Musé um national d’ Histoire naturelle,Paris.

Description.— Female holotype,length without furcal setae: 1350 ¹m. Meso- cyclops ofaveragesize, integumentornamented with small pits, scattered andlittle denseon the body,some arrangedin twolines nearthe posterior edgeof the genital doublesomite, onits ventral face (Žg. 1C); this ornamentationalso present onthe antennules,antennae, maxillae, andmaxillipeds. Th5with the usual sensillae (twomedian and two laterodistal) andbearing a fewlong hairs in alongitudinalline oneachside. Genital doublesomite (Žg. 1C)1.23 times as longas wide.Seminal receptacle well visible: anterior part withrounded lateral arms, anterior edgewith a marked