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INVERTEBRATE ZOOLOGY
ISSN 1812-9250 
ISSN 1814-0815
(online)

 

KMK

 

 

Volume 3, Number 1

 The answer to Thomas Bartolomaeus:
Larva of phoronid Phoronopsis harmeri Pixell, 1912 has trimeric coelom organization”

E.N. Temereva, V.V. Malakhov

Department of Invertebrate Zoology, Moscow State University, Vorobjevy Gory, Moscow, 119992, Russia. e-mail: temereva@mail.ru

ABSTRACT: Traditionally phoronids are considered as achricoelomate animals, because phoronid larvae and adult have trimeric coelom organization. Recent investigations of Dr. Bartolomaeus revealed that phoronids larvae have only one coelom, namely metacoel, and therefore phoronids can not be considered as archicoelomate organisms. Microscopical anatomy and ultrastructure of Phoronopsis harmeri larva coelomic system were investigated by methods of histology and electron microscopy. Larva has three parts of coelom such as protocoel, mesocoel, metacoel. The first has cylindrical shape and lies in the preoral lobe under aboral organ. The second is horseshoe-shaped which is open on the dorsal side and lies in the basis of tentacular ring. Coelomic canals go away from mesocoel horseshoe to each tentacle. Metacoel lies in the hyposphere from tentacular ring to telotroch and has shape of cylinder which gathers round the digestive tract. Metacoel divides into right and left parts by ventral mesentery. Lining of protocoel is formed by monociliary epithelial cells which connected by apical adherens junctions and ECM (extracellular matrix) lying under these cells. Thus protocoel lining reperesents true epithelium. Mesocoel lining consists of monociliary myoepithelial cells lying on ECM of ectodermal epithelium and forming wall of tentacular blood vessels in each tentacle. Monociliary myoepithelial cells form metacoel lining. Data of this work reveal that phoronids larvae of Phoronopsis genera do have trimeric organization of coelom. Trimeric organization is original state of phoronid larvae coelomic system.

KEYWOrDS: Archicoelomate conception, Phoronida, larvae, coelomic system.  

(in Russian with English Summary)

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Electra korobokkura sp. n., a new species of cheilostome bryozoan from the Pacific coast of Hokkaido, Japan

E.A. Nikulina

Institut fur Geowissenschaften der Christian-Albrechts Universität zu Kiel, Olshausenstr. 40, Kiel, D-24118, Germany

Leibniz-Institut für Meereswissenschaften, Düsternbroocker Weg 20, Kiel, D-24105, Germany. e-mail: en@gpi.uni-kiel.de

ABSTRACT: A new species of cheilostome bryozoan of the genus Electra is described from the Pacific coast of Hokkaido, Japan. The species Electra korobokkura sp.n. can be distinguished from the closely related species E. arctica by colony morphology and zooid sizes. Zooids of E. korobokkura are distinctly smaller, and colonies comprise uniserial to narrow oligoserial chains; in E. arctica, colonies usually form compact fan-shaped patches. In the diagnosis, genetic data are included: partial sequences of the 18S and 16S rDNA. The data can be used for molecular identification of the species.

KEYWORDS: taxonomy, Electra, Cheilostomata, Bryozoa.

(in English with Russian Summary)

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Description of the water mite larva Sperchon tridentatus Sokolow (Acariformes, Sperchontidae)

P.V. Tuzovskij

Institute for Biology of Inland Waters of the Russian Academy of Sciences, Borok, Yaroslavl Province, 152742, Russia. e-mail: tuz@ibiw.yaroslavl.ru

ABSTRACT: The first illustrated description of the larva of Sperchon tridentatus Sokolow and emended larval diagnosis of the genus Sperchon Kramer are given. Larvae are reared from the eggs laid by females in the laboratory settings (glass cylinders, diameter of 15 mm, and height of 10 mm). The embryonic development was completed in 11–14 days at room temperature. Idiosoma carries 18 pairs of setae (2-2-2-4-4-4-4-4-2-4-4) and 5 pairs of lyriform organs. The dorsal plate is elongate (length/width ratio 2.0), covering less than half of the dorsal surfaces of the unengorged larvae. The anterior margin of the plate is straight and wide, the posterior end is narrow. Setae Fch are longer and thicker than trichobothria Fp and Oi; setae Pi, and Pe are subequal. The anal plate may be split into several fragments, sometimes it is reduced completely. Coxae of legs I and II are rather small and triangular; coxae III are large and quadrangular. The pedipalpal tarsus carries three large plumose setae of different length, a single solenidion and four thin short and smooth setae. The larva of S. tridentatus is similar to the larva of  S. clupeifer, but differs by the structure of the pedipalpal tarsus (S. clupeifer has two long and thick and five short setae; two of the short setae are straight and serrate and one is bent and pectinate).

Genus Sperchon Kramer, larval diagnosis: with larval characters of the family Sperchontidae (Prasad, Cook, 1972); the idiosoma is elongate, oval, with 18 pairs of setae; setae Fch usually are longer and thicker than trichobothria Fp and Oi; setae Pe and Pi are approximately equal in length; coxae of legs II are usually with one seta (C3) or with none (S. setiger); the cheliceral stylet has hair-like processes and one subapical denticle; the pedipalpal tarsus has one solenidion and 5–7 simple setae.

KEYWORDS: Sperchontidae, Sperchon tridentatus, water mites, larva.

(in Russian with English Summary)

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The evolution of the supplementary apparatus in tobrilids (Nematoda: Enoplida, Tobrilidae)

S.J. Tsalolikhin

Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034, Russia. e-mail: nematoda@zin.ru

SUMMARY: The evolution of the supplementary apparatus in tobrilid nematodes is directed towards a decline in the number of supplements and intensification of their functions (in accordance with Dogiel’s principle of oligomerization of homologous organs). As a result of this process an optimum ratio is established between the capture ring of the male, which is formed at the moment of copulation (when the male winds the precloacal part of its body with the supplements around the female) and the circumference of the female body in the region of the vulva. This ratio (coefficient #/$) for the family is on the average 1.18 ± 0.06. The lower tobrilids have more than 6 supplements. The process of oligomerization occurs due to reduction of one of the middle supplements. In the higher tobrilids the normal number of supplements is constant and nearly always equals 6. As an exception there are species with 5 supplements, e.g. Epitobrilus medius. In the process of the evolution the reduction of the last weakly developed supplement 6 can be observed, e. g. in E. andrassyi. The supplementary row remains non-oligomerized in those species where there are fewer males than females. Analyzing the value of the coefficient #/$ one should take into account the notable polymorphism of the populations of the majority of tobrilid species.

KEYWORDS: Nematodes, Tobrilidae, supplementary apparatus, oligomerisation.

(in Russian with English Summary)

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Type specimens of pelagic amphipods (Crustacea: Amphipoda) described by J.A. Birstein and M.E. Vinogradov, deposited in the Zoological Museum of Moscow State University

G.M. Vinogradov1, M.E. Vinogradov2

1 A.N. Severtsov Institute of Ecology and Evolution RAS, Leninsky pr. 33, Moscow 119071, Russia. e-mail: egor@ocean.ru

2 P.P. Shirshov Institute of Oceanology RAS, Nakhimovsky pr. 36, Moscow 117997, Russia. e-mail: michvin@ocean.ru

Abstract: This article focuses on the list of 62 type specimens of pelagic amphipods (Gammaridea and Hyperiidea) described by J.A. Birstein and M.E. Vinogradov and deposited in the Zoological Museum of Moscow State University. Catalogue numbers and other relevant information, which sometimes are absent in initial publications, are given for each type specimen.

Keywords: Amphipoda, Gammaridea, Hyperiidea, pelagic species, type specimens.

(in Russian with English Summary)

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Distribution of benthic communities of invertebrates in the southern basin of Lake Baikal

L.S. Kravtsova1, 3, T.G. Potemkina1, I.V. Mekhanikova1, L.A. Izhboldina1, T.A. Akinshina2, K.V. Varykhanova2

1 Limnological Institute SB RAS, Ulan-Batorskaya 3, Irkutsk 664033, Russia.

2 Irkutsk State University, Karl Marx 1, Irkutsk 664000, Russia.  3 e-mail: lk@lin.irk.ru

ABSTRACT: The distribution of benthic invertebrate assemblages in the southern basin of Lake Baikal has been analysed using the method of principal components. The structure of invertebrate assemblages is strongly associated with geological and geomorphological irregularities the Lake Baikal bottom.

KEYWORDS: invertebrate assemblages, environmental factors, Lake Baikal.

(in Russian with English Summary)

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How many clonal species are there in the world.
Part 2. Cloning in nature and its role in formation of biodiversity

S.D. Grebelnyi

Zoological Institute, Universitetskaya naberezhnaya, 1, Saint-Petersburg 199034, Russia. e-mail: actinia@zin.ru

ABSTRACT: In the regions where fauna and flora have been exposed to recent consi-derable climatic shifts, there is a pretty good number of clonal forms in many plant and animalian taxa. Within the groups, which are capable of non-recombinating reproduction, the rapid increase in number of «species» happens through formation of new usually highly heterozygous clones, which are able to disperse to unoccupied lands (e.g. free geographical localities or ecological niches). The main source of new clonal forms (apart from some contribution produced by mutations) is extant populations of bisexual species, which, owing to recombination, can quickly generate a rich spectrum of variability by means of new allelic combinations. Possessing a rich genotypic diversity species are able to wide scale of environmental conditions and they can survive in spite of considerable climatic changes. However, due to the genetic polymorphism of the species, the proportion of individuals well adapted to given conditions is rather low. As to the clones, they are of a very low evolutionary potency compared to ancestral bisexual populations. At the same time, the successful clones are entirely composed of elite individuals that are most adapted to the current environment. Only those clonal animals and plants do well within most of a species range whereas bisexual populations are forced to settle in refuges of rather restricted space and unstable environmental conditions, where they succeed to survive due to their much higher evolutionary potency, caused by genetic polymorphism.

(in Russian with English Summary)

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