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

 

KMK

 

 

Volume 2, Number 1

Naupliar evolutionary novelties of Stenhelia peniculata (Copepoda, Harpacticoida) from Alaska affirming taxa belonging to different categorial rank

Hans-Uwe Dahms 1, Nikolaos V. Schizas 2, Thomas C. Shirley 3

1Hong Kong University of Science and Technology (HKUST), Department of Biology, Coastal Marine Lab (CML), Clear Water Bay, Hong Kong, SAR – China. e-mail: hansd@ust.hk

2Department of Marine Sciences, University of Puerto Rico, Mayagüez Campus Isla Magueyes Laboratories, P.O. Box 908, Lajas, PR 00667, Puerto Rico. e-mail: n_schizas@cima.uprm.edu

3Juneau Center, School of Fisheries & Ocean Sciences, University of Alaska Fairbanks, 11120 Glacier Hwy, Juneau, AK 99801, U.S.A. e-mail: Tom.Shirley@uaf.edu

 ABSTRACT: All six naupliar stages of Stenhelia peniculata (Lang, 1965) from Auke Bay near Juneau (Alaska) are described. Naupliar morphology within the Stenheliinae differs among species and even more at supraspecific level. Nauplii of S. peniculata are characterized by the following apomorphies compared to the only other species of Stenhelia where nauplii have been studied, namely S. palustris (cf. Dahms, Bresciani, 1993): third antennal segment bears three (S. peniculata) or two (S. palustris) medial setae at the third naupliar stage; mandibular endopod with three or four setae on outer lateral field at the sixth naupliar stage; no spinulation on mandibular exopod or strong spinulation; first maxilla with three or two setae. The nauplii of both these stenheliid species differ from those of Pseudostenhelia wellsi Coull, Fleeger, 1977 by the terminal seta of the first antenna, which is as long as the third segment (Stenhelia) or being three times as long as the third segment (Pseudostenhelia); the four middle setae of the antennal endopod are of regular size (Stenhelia), instead of two of the four being much longer; the proximal seta of the mandibular exopod being long instead of being short (Pseudostenhelia); their endopod having an outer lateral field with one long seta (Stenhelia) instead of having three long setae. A reaffirmation of the Stenheliinae Brady, 1880 is supported by the following stenheliinid apomorphies in the morphology of the nauplii (as evidenced from a comparison of Stenhelia and Pseudostenhelia, with all other oligoarthran harpacticoid nauplii as an outgroup): lateral edge of the naupliar shield bears protuberances on either side (Stenheliinae) instead of no protuberance (Oligoarthra); masticatory process of the second antenna is peculiarly fan-shaped distally (Stenheliinae) instead of tapering terminally (Oligoarthra); antennal exopod strongly developed, three-segmented and upwardly curved (Stenheliinae) instead of being four-segmented and never strongly developed (Oligoarthra); the whole mandible is of peculiar shape and orientation (Stenheliinae) instead of being common (Oligoarthra); the posterolateral field of the mandibular endopod bears a remarkable strong, inner spinulose spine (Stenheliinae) instead of lacking such spine (Oligoarthra); the three distal exopodal setae are of unique structure (Stenheliinae).

 KEYWORDS: postembryonic development, morphology, key to stages, phylogeny.

(in English with Russian Summary)

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New species of symbiotic scaleworms Asterophilia  (Polychaeta, Polynoidae) from Vietnam

 Temir A. Britayev 1, Kristian Fauchald 2

1 A.N. Severtzov Institute of Ecology and Evolution Russian Academy of Sciences, Leninsky pr. 33, 117071 Moscow, Russia. e-mail: temir@invert.sevin.msk.ru

2 Department of Zoology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, NHB MRC 0163, Washington, DC 20013–7012, USA. e-mail: Fauchald@si.edu

 ABSTRACT: During the observation of fauna associated with starfishes performed at the shallow coastal waters of Vietnam (South China Sea, Nhatrang Bay) in 1985, 1987, 1988 and 1999, the new species of symbiotic scaleworm was found. The species is similar to Asterophilia carlae, but differs in elytra with distinctive frontal pockets and micropapillae, and in middle neurochaetae with serrated edge and without enlarged basal row of serrations (semilunar pocket). The specimens were associated with starfishes Culcita novaeguineae, Protoreaster nodosus, Linckia laevigata, and with unidentified unstalked crinoids. Worms have been located on the ventral surface of starfishes or hidden in ambulacral grooves. Each infested host harbored 1 or 2 specimens of scaleworm. The prevalence of host infestation was very low in all host species and counted in C. novaeguineae. It varied from 3.3% to 13% with average meaning 8.5% (n = 188). Females were slightly larger than males. This is the first record of Asterophilia species at the coast of Vietnam and the first record of symbiotic polychaete associated with wide spread tropical starfish Culcita novaeguineae and the fifth symbiotic polychaetes recorded in Vietnamese coastal waters.

 Keywords: symbiosis, polychaetes, scaleworms, sea stars, Vietnam.

(in English with Russian Summary)

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Spiculammina delicata gen. et sp. n., a new xenophyophore from the eastern Pacific (Psamminidae)

 O.E. Kamenskaya

 P.P. Shirshov Instituite of Oceanology, Russian Academy of Sciences, Nakhimovsky Ave., 36, Moscow 117997, Russia. e-mail: okamenskaya@ocean.ru

 ABSTRACT: A new genus and new species of xenophyophores is described from the abyssal depths of the eastern Pacific. The presence of external xenophyae arranged in a surface layer and internal xenophyae in the lumen of tubular test allow us to attribute Spiculammina delicata gen. et sp. n. to Psamminidae. The new genus is distinguished from other genera of the family by tree-like form of the test.

 KEYWORDS: abyssal fauna, Protista, xenophyophores, Spiculammina delicata gen. et sp. n., taxonomy, Pacific Ocean.

(in English with Russian Summary)

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On the systematic position of some recent brachiopod species from the Norfolk Ridge (West Pacific)

O.N. Zezina

P.P. Shirshov Instituite of Oceanology, Russian Academy of Sciences, Nakhimovsky Ave., 36, Moscow 117997, Russia. e-mail: kap@sio.rssi.ru

 ABSTRACT: Five species of brachiopods were found in 7 samples obtained during the cruise NORFOLK 2. These species were known before from this region. Four of these species are common and are considered as markers of the deep-sea biofilter, distributed globally in the upper bathyal of continental slopes and seamounts. This deep-sea biofilter remains poorly explored at low latitudes of the Western Pacific. The systematic position of examined species has been clarified. Neoancistrocrania norfolki Laurin, 1992 is included in the family Valdiviathyrididae Helmcke, 1940. Stenosarina crosnieri (Cooper, 1983) is relocated to the genus Dallithyris Muir-Wood, 1959. A new genus, Laurinia gen. n., was established after the study of soft tissues of Fallax neocaledonensis Laurin, 1997.

 KEYWORDS: Brachiopods, deep-sea biofilter, new genus Laurinia.

 (in Russian with English Summary)

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Morphometric differentiation in euphausiid, Thysanoessa raschii (Crustacea, Euphausiacea), from the Barents and Laptev Seas

S.F. Timofeev

Murmansk Marine Biological Institute, Kola Science Center, Russian Academy of Sciences, Vladimirskaya St., 17, Murmansk, 183010, Russia, e-mail: timofeev@an.ru

 ABSTRACT: We examined the morphometric differentiation in Arctic krill, Thysanoessa raschii (M. Sars, 1846), collected in the Barents and Laptev Seas. At the same total body length, the lengths of the carapace, abdomen and telson were different in euphausiids from the two populations. It is suggested that a shorter abdomen length and longer carapace and telson in the Laptev Sea versus the Barents Sea specimens may be a reaction to unfavourable conditions, especially food scarcity.

 KEYWORDS: euphausiid crustaceans, Thysanoessa raschii, allometric growth.

(in Russian with English Summary)

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Fine structure of sensory organs in chaetognaths. 1. Ciliary fence receptors, ñiliary tuft receptors and ciliary loop

V.V. Malakhov, T.L. Berezinskaya, K.A. Solovyev

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

ABSTRACT: The ultrastructural characteristics of ciliary fence receptors, ciliary tuft receptors and ciliary loop were studied in chaetognats Parasagitta elegans and Serra­to­sagitta pseudoserratodentata. Two types of ciliary fence receptors were described as ciliary fence receptors and ciliary tuft receptors. Ciliary fence receptors are short cross series of monociliary cells with unusual inflated non-striated roots. Ciliary tuft receptors are the group of short longitudinal series of monociliary cells with long striated roots. Ciliary loop is a gutter in integumentary epithelium. Ciliary loop subdivided into an internal canal filled with inflated electron-lucent microvilli, and an external part carrying cilia. Possible functions of studied organs are discussed: Ciliary tuft receptors are proposed to be the tactile receptors whereas ciliary fence receptors are probably responsible for the perception of different oscillation frequencies. Ciliary loop function may be analogous to the function of fish lateral line system.

KEYWORDS: Ñhaetognatha, sensory organs, ciliary fence receptors, ciliary tuft receptors, ciliary loop, Parasagitta elegans, Serratosagitta pseudoserratodentata.

 (in Russian with English Summary)

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How many clonal species are there in the world. Part 1. The difference between clonal forms and bisexual species

S.D. Grebelnyi

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

ABSTRACT: When using the term “sexual reproduction” we usually forget that sexual process is not directly bound up with reproduction. Being the main instrument of genetic recombination, in mammals and birds it takes place in every generation and supports the diversity of genotypes. In other cases (Daphniidae, Daphniiformes, Crustacea; Aphididae, Homoptera) it only periodically restores the genetic diversity, which is inevitably lost by population while it reproduces by parthenogenesis. As a result, the population gradually converges to a mixture of a limited number of clones, each of which being comprised of genetically identical individuals. Switching over to long-term parthenogenesis (or other kind of reproduction without recombination) leads to emergence of genetically isolated, generally all-female races. The examples of such phenomenon are the beetles (Otiorhynchus, Curculionidae, and Ptinus, Ptinidae), butterflies (Solenobia, Psychidae), grasshoppers (Saga, Tettigoniidae, and Warramaba, Eumastacidae), woodlice (Trichoniscus, Trichoniscidae, Isopoda, Crustacea). Many of them, having acquired some karyological differences from their closest bisexual relatives, are often considered as separate clonal or hemiclonal species (for example, parthenogenetic lizards of the genera Cnemidophorus, Teiidae; Leiolepis, Uromastycinae; Lacerta, Darevskia, Lacertidae; Heteronotia, Gekkonidae; gynogenetic and hybridogenetic fishes Poecilia and Poeciliopsis, Poeciliidae; caudate amphibian Ambystoma, Ambystomatidae; very common European frog Rana esculenta. Most of non-recombinating races or species are characterized by higher heterozygosity and viability, many of them being of hybridogenous origin. The study of meiosis in parthenogenetic organisms makes it possible to understand the cause of competitive success of such forms in nature and fragility of clones obtained from “normal” bisexual species in the laboratory. The fact is that the animals and plants, which in natural conditions do not have true sexual reproduction, nevertheless pass all their chromosome set (or only a part of it) to their offspring in completely unmodified condition. The necessary condition of successful cloning is a deep deformation of gametogenesis, which disrupts recombination. That preserves the most favorable combinations of characters, which, having arisen by chance, succeeded in clonal competition. By examining different mechanisms of stoppage of recombination in nature (parthenogenesis, gynogenesis, hybridogenesis et ctr.), we elicit the most general features of clones as well as their advantages and limitations in comparison with bisexual Mayr’s “biological species”.

KEYWORDS: clonal competition, all-female races, unisexual species, stoppage of recombination, parthenogenesis, gynogenesis, hybridogenesis, apomixis, geographic distribution of polyploids, “biological species”, climatic changes.

  (in Russian with English Summary)

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Ya. I.  Starobogatov (1932-2004)

V.V. Malakhov,  S.D. Stepaniants

  (in Russian)

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Last updated: Tuesday, 07/08/2014