Clavinema mariae (Dracunculoidea: Philometridae) (Osteichthyes: Gadiformes) .. 1 , .. 2 , .. 2 1 . .. , ., 33, 119071, . e-mail: sokolovsg

The fine structure of the nervous system in plerocercoid Ligula intestinalis (Diphyllobothriidae) has been studied. The ultrastructure of the cerebral ganglion, the main nerve cords and peripheral nervous system has been described. The cerebral ganglion has complicated microanatomy. It consists of symmetric pair frontal and lateral lobes connected by the massive median commissure, and ventral azygos lobe, located in the center and on the ventral surface of the commissure. Two crossed ventral nerves are originated from the unpaired median (ventral) lobe. It was found, that the neurons in the lateral lobes and the commissure have asymmetrical position (localization neurons in the lateral lobes and the commissure has dorso-ventral polarity): large neurons (2040 m) are concentrated on the dorsal surface of the cerebral ganglion. We found four types of neurons with different fine structure and size, peripheral neurosecretory cells and undifferentiated cells. Three types of synaptic contacts have revealed in neuropiles. Giant axon occurred as part of the main cord. On the surface membrane of the giant axon are numerous incoming synapses. The peripheral nervous system consists of numerous compact bunches of nerve processes taking place along the longitudinal and dorso-ventral muscle fibers. Also three types of sensory organs were found in the tegument: one type a ciliate and two types unciliate receptors. Comparative analysis of nervous system organization in representatives of the two orders Diphyllobothriidea and Bothriocephalidea showed that the cerebral ganglion L. intestinalis possesses bilateral symmetry, characterized by the presence of the ventral lobe, ventral nerves and the dorso-ventral polarity in the arrangement of neurons and exiting nerves. On the contrary, the cerebral ganglion of Triaenophorus nodulosus (Bothriocephalidea) has a double-beam symmetry: it has symmetrical lobes in ganglion with symmetrical dorsal and ventral nerves, lack of lobe in the median commissure, and send symmetrical dorso-ventral rootlets in the bothria. Our data confirm the belonging of the studied species to different groups and support the idea of separation Pseudophyllidea sensu lato into two new orders Diphyllobothriidea and Bothriocephallidea.

We found two species of Cladocera (Crustacea: Branchiopoda), namely Latonopsis cf. australis Sars, 1888 (family Sididae) and Alona cambouei Guerne et Richard, 1893 (family Chydoridae), in the Unhere hot water springs near Pali, State of Maharashtra, India at temperatures of 34.536.7 C. Our finding is the first record of cladocerans with exact species determination in hotsprings of the Oriental zone.

Biochemical genetic approach was applied to clarify the taxonomic status of the hermit crab Pagurus gracilipes which was compared with five species of the family Paguridae (P. brachiomastus, P. ochotensis, P. middendorffii, P. proximus, P. minutus) and with two species of the family Diogenidae (Diogenes nitidimanus and Stratiotes nigroapiculus) using 18 allozyme loci. Genetic identity values between P. gracilipes and species of the family Paguridae (from 0.6110.117 for P. gracilipes vs P. proximus, to 0.2490.102 for P. gracilipes vs P. middendorffii) suggest that this species should retain its position in the genus Pagurus. This conclusion is supported by similar average identity value between other species of the genus Pagurus (I=0.4440.110) and low genetic similarity between the genera Diogenes and Stratiotes (I=0.1670.084) and between the families Paguridae and Diogenidae (I=0.1020.005).

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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.