ISSN 1812-9250 
ISSN 1814-0815





Volume 7, Number 1

Published online 30/12/2010

Three new interstitial species of Remaneicaris Jakobi, 1972 (Copepoda: Harpacticoida: Parastenocarididae) from Southern and Southeastern Brazil

Paulo H.C. Corgosinho1, Pedro Martinez Arbizu2, Edinaldo N. dos Santos-Silva3

1,2DZMB — Forschungsinstitut Senckenberg, Sudstrand 44, 26382 Wilhelmshaven, Germany.

1 Center Unesco/HIDROEX (International Center ror Education, Capacity Building and Applied Research in Water), Frutal (MG), Brazil.

3Plankton Laboratory, CPBA/INPA, Av. Andre Araujo, 2936 Petrópolis, 69011-970, Manaus-AM, Brazil.

ABSTRACT: Three new species of the genus Remaneicaris from Southern and Southeastern Brazil are described. The new species are closely related to R. analuizae, R. euniceae, R. tageae and R. divae, sharing the presence of a hyaline margin on the 9th segment of male antennule. Remaneicaris itacambirucui sp.n., R. insolitus sp.n. and R. ivoneae sp.n. differ by: number of integumental windows on the 2nd and 5th urosomites; ornamentation of the telson, with postopercular ornamentation shared by R. insolitus sp.n. and R. itacambirucui sp.n.; shape of the swimming leg 3 exopod and armature of the swimming leg 3 endopod, with straight exopod and unarmed endopod shared by R. insolitus sp.n. and R. ivoneae sp. n.; and morphology of the swimming leg 4 endopod with a similar condition shared by R. insolitus sp.n. and R. itacambirucui sp.n. Remaneicaris itacambirucui sp.n. seems to be closely related to R. ivoneae sp.n. with which it shares the presence of a hyaline inner margin on the outer spine of male’s swimming leg 3. Remaneicaris insolitus sp.n. seems to be closely related to R. divae, sharing a continuous transversal row of spinules on the antero-ventral margin of the telson. In the absence of more informative characters, the exact phylogenetic position of R. itacambirucui sp.n. and R. ivoneae sp.n. within a monophyletic group of species closely related to R. analuizae is difficult to determine.

KEY WORDS: Copepoda, Parastenocarididae, Remaneicaris, new species, Brazil.

(in English with Russian Summary)

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Proales tillyensis sp.n. (Monogononta: Proalidae), a new rotifer species from North-West Germany, with reconstruction of its somatic musculature

E.F. Wilts, W.H. Ahlrichs

Systematics and Evolutionary Biology, Department of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany.

ABSTRACT: We here describe a new proalid rotifer species Proales tillyensis sp.n. from Oldenburg, North-West Germany. The species was initially found in the ph-neutral water of Lake Tilly in August 2006. Its description is based on light and electron microscopy, providing different views of both the whole specimen and its trophi. Additionally, the body musculature of the species was visualized by confocal laser scanning microscopy using fluorescent-labelled phalloidin and compared with the musculature of other Proales species. Proales tillyensis sp.n. resembles P. fallaciosa Wulfert, 1937 and P. decipiens (Ehrenberg, 1832) but differs in its ecology. Furthermore it can be diagnosed from the former species by the absence of a knob-like projection between the toes, the small body size, the number of uncus teeth and the organization of body musculature. From the latter species it can be diagnosed by the number of uncus teeth, the small body size and the lack of a constriction between stomach and intestine.

KEY WORDS: Proales tillyensis sp.n., Rotifera, Proalidae, CLSM, somatic musculature.

(in English with Russian Summary)

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A new psammophilic species of the genus Diacyclops (Crustacea: Cyclopoida) from the littoral zone of Lake Baikal (East Siberia)

Natalya G. Sheveleva1, Oleg A. Timoshkin, Viacheslav N. Aleksandrov, Ekaterina P. Tereza

Limnological Institute of Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya, 3, 664033 Irkutsk, Russia.

ABSTRACT: An illustrated description of Diacyclops zhimulevi Sheveleva et Timoshkin, sp.n. (Crustacea, Cyclopoida: Cyclopidae) is provided. The new species is widely distributed along the southwestern coast of Lake Baikal, inhabiting sandy bottoms of the shallow littoral zone. A comparison is made with the previously studied and closely related species Diacyclops eulitoralis Alekseev et Arov, 1986 from the sandy interstitial environment of Lake Baikal. The new species differs from its most closely related species D. eulitoralis by a combination of characters: shorter, nearly square caudal furca (furcal index 1:1 in contrast to 1:3.5 in D. eulitoralis), a larger number of antennular segments, and a different segment pattern of the swimming legs: 2.2/3.2/3.3/3.3 compared to 2.2/3.2/3.2/3.2 in D. eulitoralis. The armament of the distal endopodal segments of the swimming legs 1 and 2 is generally characterized by presence of a long and stout apical spine. The two species are also clearly divergent in ecology: D. eulitoralis inhabits the upper surf zone of the beach and may fairly be called an interstitial species (Alekseev & Arov, 1986; Boxshall et al., 1993), whereas the new species colonizes sandy bottom of the littoral zone.

KEY WORDS: Diacyclops zhimulevi Sheveleva et Timoshkin, sp.n., Cyclopoida, Cyclopidae, Lake Baikal, psammon.

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Ultrastructural study of spermatogenesis in the Pacific oyster Crassostrea gigas (Bivalvia: Ostreidae) from the Sea of Japan

O.V. Yurchenko, V.I. Radashevsky, A.A. Reunov

A.V. Zhirmunsky Institute of Marine Biology, FEB RAS, Vladivostok, 690041, Russia.

ABSTRACT: Spermatogenesis in the Pacific oyster Crassostrea gigas from the Sea of Japan, was studied with transmission and scanning electron microscopes. Spermatogonia are characterized by two kinds of nuage-like material (large germinal body-like structure and/or cluster of small globules), cisternae of endoplasmic reticulum and prominent Golgi body that gives rise to occasional proacrosomal vesicles. Spermatocytes contain numerous proacrosomal vesicles, while both kinds of nuage-like material are rarely observed at this stage. A large single acrosomal vesicle is formed by fusion of proacrosomal vesicles in the basal part of each spermatid. After migration to the apical position of the acrosomal vesicle becomes cup-shaped; the round nucleus assumes barrel-like outlines. Part of spermatocytes and spermatids develop with flagellum while some spermatogenic cells are characterized by intracellular axoneme. Spermatozoa have an electron-lucent knob situated on top of the acrosome. This type of knob has never been described earlier in the C. gigas and other ostreids. The pattern of C. gigas spermatogenesis which includes many ultrastructural features may be used in future comparative studies of sperm development in Ostreidae and other mollusks. 

KEY WORDS: Crassostrea gigas, Ostreidae, sperm cells, ultrastructure.

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Biology of the shrimps Sergia regalis (Gordon, 1939) (Crustacea: Sergestidae) in waters of Namibia

R.N. Burukovsky

Kaliningrad state technical university, 236000 Kaliningrad, Russia.

ABSTRACT: The circumtropical species Sergia regalis belongs to the mesopelagic strongly migratory species. In Namibia waters (South-East Atlantic) these shrimps feed on the euphausiids, radiolarians and copepods which form 28,5, 30,9, 32,7% of volume of virtual bolus respectively. At the early stages of ontogenesis S. regalis is a grazing plankton feeder-predator which feeds mainly on copepods and small radiolarians (micro- and mesoplankton). Having grown up, the feed on predatory euphausiids including Nematoscelis megalops (macroplankton) thus becoming aggressive plankton predator. S. regalis is a member of grazing food chain. These shrimps are basic objects of feeding objects for the fish Merluccius polli oss Angola. S. regalis provides 18% of Merluccius polli virtual bolus weight.

KEY WORDS: plankton, food chains, Sergia regalis, distribution, biology, feeding, hunting mode.

(in Russian with English Summary)

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