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

 

KMK

 

 

Volume 1, Number 1

 

Fine morphology of larvae of sea spiders (Arthropoda: Pycnogonida) from the White Sea

 E.V. Bogomolova, V.V. Malakhov

 Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899, Russia. 

ABSTRACT: External morphology of pycnogonid larvae (Arthropoda, Pycnogonida) of four species with different types of postembryonic development was studied with scanning electron microscopy. The first type is characterized by the following features: the larvae hatch at the protonymphon stage; larval body length varies between 100 and 200 mm; early larvae stay attached to male’s ovigerous legs; later they become ectoparasites of hydrozoans. Two species, Achelia borealis (Schimkewitsch, 1895) (Ammotheidae) and Nymphon longitarse (Kröyer, 1845) (Nymphonidae) belong to the first type. The second type has the following set of characters: the larvae hatch at protonymphon stage; larvae are extremely small (about 50 mm); after hatching, they leave male and start endopararasitiñ life on hydrozoans; larvae lack spinning spines and web glands. Phoxichilidium femoratum (Rathke, 1799) (Phoxichilidiidae) belongs to the second type. The third type is characterized by hatching of the big-size (up to 300 mm) lecitotrophic larvae with the buds of the walking legs (i.e. the first postembryonic stage does not correspond to the protonymphon stage of other species) staying attached to the ovigers of male up to late development stages. Pseudopallene spinipes (Fabricius, 1780) (Callipallenidae) belongs to the third type. The newly hatched larvae were studied in all the four species. The following structures are described: elaboration by small denticles on chela fingers, on spinning spines and on terminal segments of second and third legs of protonymphon; pores of proboscidean glands and of chela glands (the latter are described in P. spinipes too; for larvae with the third type of development chela glands have not been found before). Larvae have sensilla of different shape (simple or ramified into 2 to 4 hairs, smooth or plumose). The structure of sensilla can vary in different specimens of the same species and even in the same specimen. Protonymphon larvae show regular arrangement of sensilla. Number of lsensilla correlates with size of the protonymphon larva. Pycnogonid larvae have bilaterally arranged slit-like pores of integumentary glands. More advanced larvae (investigated in A. borealis and P. spinipes) bear long setae on the cuticle of legs. The number of sensilla and slit-like pores increases from stage to stage while the regularity of their arrangement disappears. In A. borealis, coupled pores appear on ventral side close to bases of the first and (later) second walking legs. They are supposed to be external openings of enigmatic ventral organs associated with developing ventral ganglia.

 KEYWORDS: Pycnogonida, sea spiders, postembryonic development, larvae, fine morphology.

  (in Russian with English Summary)

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Exclusion of the Polyarthra from Harpacticoida and its reallocation as an underived branch of the Copepoda (Arthropoda, Crustacea)

 Hans-Uwe Dahms

 Hong Kong University of Science and Technology/ Dept. Biology — Coastal Marine Lab/ Kowloon — Clearwater Bay/ Hong Kong/ SAR China. e-mail: hansd@ust.hk

 ABSTRACT: There is no reasonable autapomorphy, either from the naupliar or the adult organization, which justifies a monophylum Harpacticoida (sensu Lang, 1948). This implies a paraphyletic situation of this taxon, comprising two independent monophyletic taxa, the Polyarthra and the Oligoarthra. To solve this problem, the present study will provide justifying arguments for the exclusion of the taxon Polyarthra from the Harpacticoida, which then is exclusively represented by the monophylum Oligoarthra. When Polyarthra are excluded from the Harpacticoida, than Oligoarthra share the following naupliar synapomorphies: postmaxillar limbs widely spaced, antennal coxa with strong gnathobase, antennal endopodite elongate, mandibular endopodite an elongate process. Based on naupliar characters, Polyarthra are allocated as an underived taxon of the Copepoda, sharing with all other Copepoda the following naupliar characters: antennule 5-segmented, antennal exopodal segments increase from 6 at N I to a final number of 9 at N IV, antennal endopodite is 1-segmented, maxilla absent, swimming performance and life history, dorsocaudal process, antennule segment homologues, larger number of segments in naupliar antennal endo- and exopodites.

 KEYWORDS: nauplii, development, phylogenetic systematics, ß-systematics, evolution, Polyarthra, Harpacticoida, Copepoda.

(in English with Russian Summary)

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The first occurrence of the Tantulocarida for the White Sea

 P.N. Kornev

Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899, Russia. 

ABSTRACT: Two species of Tantulocarida (Crustacea, Maxillopoda) belonging to the families Microdajidae and Basipodellidae and parasitisiting on copepods and tanaidaceans were found at the Kandalaksha Bay of the White Sea. This is the first report of Tantulocarida for the White Sea, as well as other Russian seas. Morphology of the tantulus larva, male and parthenogenetic female of Microdajus sp. (Microdajidae) was examined.

 KEYWORDS: Tantulocarida, Microdajus, Tanaidacea, parasitism.

  (in Russian with English Summary)

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The interstitial Polychaeta of Russian Seas

 E.A. Mastepanova

  Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899, Russia. e-mail: helianata@rambler.ru

 ABSTRACT: 52 species of interstitial polychaetes are found in seas of Russia. 20 species are found in the Black Sea, 15 — in the White Sea, 13 — in the Barents Sea, 9 — in the Sea of Japan and 5 — in other seas of the Far East. Baltic Sea is assumed to be inhabited by no less than 11 species. There is no information on the interstitial polychaetes in the Azov Sea, the Caspian Sea, the Kara Sea, the Laptev Sea, East Siberian Sea, the Bering Sea and the Sea of Okhotsk.

 KEYWORDS: Polychaeta, interstitial fauna.

(in Russian with English Summary)

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Population ecology of two simpatric polychaetes, Lepidonotus squamatus and Harmothoe imbricata (Polychaeta, Polynoidae), in the White Sea

 Maria Plyuscheva 1, Daniel Martin 2, Temir Britayev 1

1 A. N. Severtzov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky pr. 33, Moscow 117071, Russia. 

2 Centre d’Estudis Avançats de Blanes (CSIC), carrer d’accés a la Cala Sant Francesc 14, 17300 Blanes (Girona), Catalunya (Spain).  e-mail: dani@ceab.csic.es

 ABSTRACT: Under the critical environmental conditions of the White Sea, Lepidonotus squamatus and Harmothoe imbricata coexist in the same habitat, often showing recurrent alternations in dominance. L. squamatus is a long-living, slow growing broadcast spawner, while H. imbricata is a short-living and quick growing species, with complex reproductive behaviour. These different life strategies may allow them to respond in a different way to the environmental limitations of the study site, this likely being the most appropriate explanation to the observed alternation in dominance.

 KEYWORDS: Population dynamics; growth; scale-worms; the White Sea. 

(in English with Russian Summary)

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Redescription of two species of the genus Leydigiopsis Sars, 1901 (Branchiopoda, Anomopoda, Chydoridae

 Artem Yu. Sinev

Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899, Russia.

ABSTRACT: The two insufficiently known South American cladoceran species, Leydigiopsis curvirostris Sars, 1901 and Leydigiopsis megalops Sars, 1901, were redescribed from the type material. Detailed morphology of the trunk limbs of these species and morphology of male L. megalops were studied for the first time. Species of the genus Leydigiopsis combine clearly plesiomorphic characters — primitive morphology of head pores, male postabdomen similar to that in females, and apomorphic characters — long rostrum, antennules of unusual morphology, broad postabdomen with well developed postanal denticles. Analysis of morphology suggests that Leydigiopsis belongs to the group of the small tropical genera, like Euryalona, Tretocephala, long ago separated from the main trend of Aloninae and retain numerous plesiomorphic characters.

 KEYWORDS: Cladocera, Leydigiopsis, morphology, systematics.

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Distinctive features of the microscopical anatomy and ultrastructure of the metanephridia Phoronopsis harmeri Pixell, 1912 (Phoronida, Lophophorata

 E.N. Temereva, V.V. Malakhov

  Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899, Russia.  

ABSTRACT: The microscopical anatomy of metanephridia Phoronopsis harmeri (Phoro­nida) was described. Sexual dimorphism in the structure of the distal parts of metanephridia was found and described. Female metanephridium has two ciliated funnels, whereas male metanephridium has only one. Description of the fine structure of all metanephridial parts (funnel, ascending and descending branches) was given. Epithelium of the nephrostome consists of myoepithelial cells with myofibrils in the apical parts of the cells. Miofibrils are also found in the apical and basal parts of cells of the ascending metanephridial branch. The differences between the fine structure of the ascending and descending metanephridial branches were found and described. Epithelial cells of the descending branch contain many cisterns of the rough and smooth endoplasmic reticulum, but these cells practically lack mitochondria. In contrast, epithelial cells of the ascending branch have many mitochondria and very few cisterns of the endoplasmic reticulum. These differences were discussed in the view of different functions of ascending and descending metanephridial parts.

KEYWORDS: Phoronida, ultrastructure, metanephridium.

(in Russian with English Summary)

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Last updated: Tuesday, 07/08/2014