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

 

KMK

 

 

Volume 8, Number 2

Published online 3/02/2012

The evidence of metamery in adult brachiopods and phoronids

Elena N. Temereva, Vladimir V. Malakhov

1 Department of Invertebrate Zoology, Biological Faculty, Moscow State University, Moscow 119992, Russia.

2 Laboratory of Biology of Marine Invertebrates, Far East Federal University, Vladivostok 690014, Russia.

ABSTRACT: There are both metameric and nonmetameric animal body plans in each of the three main branches of the bilaterian tree – the Ecdysozoa, the Deuterostomia and the Lophotrochozoa. Has metamery originated independently in these groups or is it a synapomorphy of all Bilateria? If the latter is correct, we might expect to find remnants of metamery in nonmetameric forms. The Lophophorata seems to be the only group of main bilaterian groups that lacks metamery. Here, we infer that the lateral mesenteries of brachiopods and phoronids are metameric in nature and originated from dissepiments between segments of trunk coelomic sacks of an oligomerous ancestor. In addition to preoral and lophophore coeloms, brachiopods and phoronids demonstrate a metameric subdivision of the body coelom. The trunk coelom of recent brachiopods and phoronids is a product of partial fusion of three or two segments, respectively. The lateral mesenteries in phoronids and brachiopods bear funnels of excretory organs like the dissepiments of true metameric animals (for example, annelids). In both groups, the lateral mesenteries are situated at an angle to the main axis of the body and always at a right angle to the axis of metamery. We conclude that metamery was present in ancestral Lophrophotrochozoans and in the common ancestor of all Bilateria but has since been reduced in some groups. The reduction of metamery in phoronids and brachiopods is correlated with strong changes in their body plan. We suggest that lophophorates are primitive lophotrochozoans because they retained some plesiomorphic features.

KEY WORDS: Lophotrochozoa, phylogeny, lateral mesenteries, metamorphosis, body plan.

(in English with Russian Summary)

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A new species of Rhodinicola (Copepoda: Clausiidae), parasitic copepod of the shell-boring polychaete Polydora brevipalpa (Annelida: Spionidae) from the Sea of Japan

Tagea K.S. Björnberg1, Vasily I. Radashevsky2

1 Centro de Biologia Marinha, Universidade de São Paulo, C.P. 71, 11600-000, São Sebastião, SP, Brasil.

2 A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, 17 Palchevsky Street, Vladivostok 690041, Russia.

3 Far Eastern Federal University, 8 Sukhanov Street, Vladivostok 690091, Russia.

Abstract: The new clausiid copepod Rhodinicola polydorae sp.n. is an ectoparasite of a spionid polychaete Polydora brevipalpa Zachs, 1933 in Peter the Great Bay of the Sea of Japan (East Sea). The host polychaete bores into shells of the Yesso scallop Mizuhopecten yessoensis (Jay, 1857). This is the first report of annelidicolous copepods from the Sea of Japan (East Sea) and the first description of a copepod parasitic on spionid polychaetes from Asia.

Key words: clausiid copepod, annelidicolous parasite, adult morphology. 

(in English with Russian Summary)

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Parastylodactylus matsuzawai sp.n. (Caridea: Stylodactylidae), a new shrimp from Japanese waters

R.N. Burukovsky 

Kaliningrad State Technical University, Kaliningrad 236000, Russia.

ABSTRACT: Parastylodactylus matsuzawai sp.n., is described from Japanese waters and is close to P. semblatae Cleva, 1990. Both species feature rounded pleura of abdominal somites, a tiny supraorbital spine, and five pairs of dorsal spines on telson. It differs from P. semblatae by the armature of the dorsal side of the rostrum (30–39 spines in P. semblatae vs. 23 in P. matsuzawai sp.n.), by the length of the antennular peduncles (1/3 of scaphocerite length in P. semblatae vs. 1/2 in P. matsuzawai sp.n.), as well as by the morphology and armature of the pereiopods 3–5. In P. semblatae the ischio-meral suture is only present in pereipods 5, while in P. matsuzawai sp.n. it is present in pereiopods 4 and 5. P. matsuzawai sp.n. lacks a proximal spine on the ischiomerus of the 3rd pereipods, which are armed with a single subdistal spine; the ischiomera of 4th pereiopods have 3 spines, those of 5th pereiopods 2 spines (subdistal and median), whereas P. semblatae has only one subdistal spine on the 4th pereiopods and 3 spines in the distal ½ of ischiomerus of the 5th pereiopods. The new species is also more reddish than P. semblatae

KEY WORDS: Parastylodactylus matsuzawai sp.n., new species, Japan.

(in English with Russian Summary)

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Tenonia elegans sp.n., a new polynoid species (Polychaeta) from the shelf of north east Sakhalin Island, Sea of Okhotsk

Inna L. Alalykina

A.V. Zhirmunsky Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Far Eastern Federal University, Vladivostok 690041 Russia.

ABSTRACT: A new polynoid species Tenonia elegans sp.n. is described from the shelf of north east Sakhalin Island. Till now the genus Tenonia remained monotypical. It is recorded for the first time for Sea of Okhotsk. The detailed description of the new species is given and its differences from a closely related species are shown: anterior pair of eyes situated in front of widest point of prostomium; the presence of papillae on antennae, palps and cirri; tentaculophores with 3–4 stout, curved setae on anterior face. This new species differs also from T. priops in possessing smaller sizes of eyes and less numerous setae in parapodia. 

KEY WORDS: Polychaeta, Polynoidae, Tenonia elegans sp.n., morphology, taxonomy, Sakhalin, Sea of Okhotsk.

(in Russian with English Summary)

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Genetic diversity of Eukrohnia hamata (Chaetognatha) in the South Atlantic: analysis of gene mtCO1 

D.N. Kulagin1, A.N. Stupnikova1, T.V. Neretina2, N.S. Mugue3

1 P.P.Shirshov Institute of Oceanology Russian Academy of Science, 36, Nakhimovsky prospect, Moscow, 117997, Russia.

2 White Sea Biological Station, Department of Biology Lomonosov Moscow State University, P.O. Box 20, Glavpochtamt, Kandalaksha raion, Murmanskaya oblast 184042, Russia.

3 Russian Federal Research Institute of Fisheries and Oceanography, 17 Verhnyaya Krasnoselskaya, Moscow 107140, Russia.

ABSTRACT: Genetic diversity and structure of the cosmopolitan chaetognath Eukrohnia hamata became the object of our research. The material was partly collected in the Atlantic Sector of the Sothern Ocean (17 specimens) and partly taken from the GenBank NCBI (2 specimens from Arctica and 3 specimens from South East Atlantic). All 22 specimens analyzed had unique haplotypes in their 5’ COI gene fragment (“barcoding” region) mtDNA sequences. Four distinct lineages were revealed by the phylogenetic analysis. These lineages (populations) had significant genetic differences that made 7–13% of the nucleotide substitutions and were geographically separated. The boundaries of their distribution are the large-scale oceanic fronts. Antarctic population can be distinguished in the Atlantic sector of the Southern Ocean to the south of the Polar Front in the Antarctic zone. To the north of the Polar Front in the Polar Frontal Zone and the Subantarctic Zone — Subantarctic population can be distinguished. Antarctic Circumpolar Current maintains genetic homogeneity of the Antarctic and Subantarctic populations of E. hamata within the whole Atlantic sector of the Southern Ocean. Tropical population was distinguished to the north of the Subtropical Front, but individuals of E. hamata from this lineage can reach the Subantarctic Zone with the rings of the Subtropical Front.

KEY WORDS: Zooplankton, chaetognaths, molecular phylogeny, the Atlantic Ocean, Southern Ocean.

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