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Diversity and Distribution of Peritrich Ciliates on the Snail Physa acuta Draparnaud, 1805 (Gastropoda: Physidae) in a Eutrophic Lotic System

Freshwater gastropods represent good models for the investigation of epibiotic relationships because their shells act as hard substrates, offering a range of microhabitats that peritrich ciliates can occupy. In the present study we analyzed the community composition and structure of peritrich epibionts on the basibiont freshwater gastropod Physa acuta. We also investigated the spatial distribution of these ciliates on the shells of the basibionts, assuming the premise that the shell is a topologically complex substrate. Among the 140 analyzed snails, 60.7% were colonized by peritrichs. We observed seven peritrich species: Epistylis plicatilis and Epistylis sp. (Epistylididae); Opercularia articulata (Operculariidae); Carchesium polypinum, Vorticella campanula and Vorticella sp. (Vorticellidae) and Thuricola kellicottiana (Vaginicollidae). We observed a high prevalence of epibiosis (＞ 60%) when all species of ciliates were considered conjunctly. However, the prevalence was low (1-58%) when each species was considered separately, reflecting their aggregate distribution pattern. The most prevalent species were Epistylis sp. (58.60%), Vorticella sp. (14.30%) and O. articulata (13.60%). Although the epibionts were distributed through the shell's entire extension, we observed greater values of abundance, density, diversity and dominance on the dorsal surface. Only Epistylis sp. was widely distributed on the ventral surface. We also observed that the peritrichs predominantly occupied the areas of the shell delimited by the sutures. We interpreted these distribution patterns considering that the peritrichs select their attachment sites under pressures related to basibiont behavior, physical forces that may dislocate them and protective characteristics of the shell's areas.

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From an Old Eroded Carapace: Rediscovery of the Majid Crab Leptomithrax sinensis Rathbun, 1916 (Crustacea, Brachyura, Majidae) from Taiwan and Japan

The majid crab Leptomithrax sinensis Rathbun, 1916 was previously only known from the holotype, a detached and partially eroded carapace collected during the Albatross Philippine Expedition in 1908 from the northern part of the South China Sea. Recent collections of fresh material from precious coral harvest sites off northeastern Taiwan, and Shikoku, Japan made verifying this poorly known species possible. The species is considered to be valid and is here redescribed, illustrated, and compared with its closest East Asian congener, L. bifidus (Ortmann, 1893).

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Neotype Designation for the Marine Flatworm, Acanthozoon alderi (Polycladida: Cotylea: Pseudocerotidae), from India with Comments on the Taxonomical Status of the Genus

Acanthozoon alderi is an ovoid, medium-sized pseudocerotid. Body margin ruffled; pseudotentacles black and pointed, with white tips. Dorsal surface covered with papillae, except for the cerebral region. Background colour light brown, with marbled blackish pattern, middorsal black band with white blotches; black submarginal band and marginal white rim. This species was described from Borneo; however, no type specimen was designated or deposited in any museum by the author. Many nomenclature problems and misidentification have been encountered with this species (it has been identified as Acanthozoon sp. in many instances). Thus, it is necessary to designate a neotype to solve the problems of doubtful and confusing identities and maintain nomenclature stability. The present paper details internal anatomy for the first time and makes important observations about the nominal status of the genus.

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New Data on the Systematics of Comb-fin Squids Chtenopteryx spp. (Cephalopoda: Chtenopterygidae) from the Canary Islands

The systematics of the comb-fin squid species is problematic and poorly resolved. In total, 53 specimens of comb-fin squids (Chtenopteryx spp.) were caught at depths ranging from 30 to 800 m off the Canary Islands (NE Atlantic Ocean). Mantle lengths of the individuals ranged from 18 to 43 mm and the sample included immature, mature male and mature female specimens. Two species of comb-fin squids, Chtenopteryx canariensis and C. sicula, were identified by combining traditional morphological characters with a molecular analysis of a fragment of the cytochrome c oxidase subunit I (COI) gene. Intra- and interspecific genetic distances and maximum likelihood tree analyses based on COI sequences available from GenBank suggest the existence of at least four species, two from the Pacific and two from the Atlantic Ocean. Our data expand the current geographic range of C. canariensis from the NE to NW Atlantic. In the GenBank database, several sequences of comb-fin squid in different species-specific clades have been attributed only to C. sicula, indicating the possible existence of cryptic species and the need to re-analyse these data.

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High Fecundity, Rapid Development and Selfing Ability in Three Species of Viviparous Land Snails Phaedusinae (Gastropoda: Stylommatophora: Clausiliidae) from East Asia

Life history traits are important yet understudied aspects of ecological diversification in land snail faunas. To acquire information for comparative analysis of gastropod life cycles, we conducted experimental breeding of three viviparous clausiliids from Japan and Taiwan. Under laboratory conditions, Tauphaedusa sheridani (Pfeiffer, 1866), T. tau (O. Boettger, 1877) and Stereophaedusa (Breviphaedusa) jacobiana (Pilsbry, 1902) featured similar times to complete shell growth (12-16 weeks), age of first reproduction (23-24 weeks) and annual fecundity (143- 173 neonates per pair of snails). The maximum number of eggs retained in genital tract reaches nine for T. sheridani, 11 for T. tau, and seven for S. jacobiana. The ratio between average shell height of neonate and adult varied between 13.5% for T. tau, 13.9% for T. sheridani, and 16.7% for S. jacobiana. All species were able to self-fertilize. Exposure to long drought affects intrauterine embryo development in all species; additionally, it results in parent and embryo mortality in S. jacobiana. Observed differences in the structure of the egg envelope among studied species point to greater than expected differentiation of developmental processes in viviparous Phaedusinae of East Asia.

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Effect of Group Density on the Physiology and Aggressive Behavior of Male Brandt's Voles (Lasiopodomys brandtii)

Population density is well known to influence animal physiology and behavior. How population density affects the aggressive behavior of the Brandt's vole (Lasiopodomys brandtii) is, however, little known. The aim of this study was to investigate the effect of group density on physiologic responses and aggressive behavior of male Brandt's voles and their potential underlying neuro-mechanism. The results show that increasing group density led to elevated serum corticosterone levels and increased spleen weight; it also induced more male-male aggressive behavior. By contrast, it had a negative effect on body growth and the weight of testis and epididymis. Aging also increased male-male aggressive behavior. Higher density reduced mRNA levels of tryptophan hydroxylase 2 (TPH2), 5-hydroxytryptamine receptor 1A (5HT1A), and 5-hydroxytryptamine receptor 1B (5HT1B) in the amygdala and the dorsal raphe nucleus (DRN). Our results demonstrate that higher population density can intensify stress reactions and male-male aggressive behavior in Brandt's voles at the price of inhibiting body growth and reproduction. Serotonergic systems in the amygdala and the DRN may take part in the control of aggressive behavior among male voles. Our results provide novel insights into the neuro-mechanism underlying the influence of population density on aggressive behavior in Brandt's vole, and imply that aggressive behavior may play an important role in the population fluctuation of the animal.

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Cytoplasmic UV-R Absorption in an Integumentary Matrix (tunic) of Photosymbiotic Ascidian Colonies

In didemnid ascidians with cyanobacterial symbionts, the tunic has a specific peak absorbing ultraviolet radiation (UV-R) due to the presence of ultraviolet (UV)-absorbing compounds, which probably include mycosporine-like amino acids (MAAs). The UV-R absorbing tunic is supposed to protect the symbionts in the common cloacal cavity of the host colony. The histological distribution of UV-R absorption in the tunic was examined using a UV light microscope equipped with a digital camera, from which the low-pass filter of the UV-sensitive image sensor was removed. The cell peripheries of tunic bladder cells and cell-like objects were visualized with the trans-illumination of UV light, indicating UV-R absorption at that site. In contrast, tunic matrix and vacuolar content of tunic bladder cells appeared to lack of UV-R absorption, allowing damaging wavelengths to penetrate. Accordingly, UV-absorbing compounds are expected to be contained in the cytoplasmic matrix of tunic bladder cells and possibly other types of tunic cells.

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Reproductive Ecology and Biodiversity of Freshwater Eels around Sulawesi Island Indonesia

Sulawesi Island of north-central Indonesia is located in a region where at least 6 species of tropical anguillid eels are present, but the reproductive ecology and biodiversity of these eels in each area of the Indonesian archipelago remains poorly understood. Some information about these species was obtained from collections of their leptocephalus larvae made during several times of the year and from year-round collections of their recruitment-stage glass eels at a few locations. A sampling survey of anguillid leptocephali was conducted in March 2010 in both the Celebes Sea and Tomini Bay of Sulawesi Island to learn about the biodiversity and reproductive ecology of the eels in the region. Twenty-eight anguillid leptocephali were collected at 13 different stations, with genetic identification indicating that 3 species of eels had spawned in the two areas. Larvae were more abundant in the Celebes Sea (N = 21; 16.0-52.1 mm TL) than in Tomini Bay (N = 7; 9.6-54.8 mm). The abundant 16-21 mm size-class of Anguilla bornensis in the Celebes Sea indicated that species had recently spawned there, and spawning had also occurred in Tomini Bay by A. celebesensis (17.4 mm). These data and previous life history information suggest that A. celebesensis may have two spawning seasons in the Celebes Sea, but only one main spawning season in Tomini Bay. Anguilla borneensis may spawn at several times of the year in the Celebes Sea. Anguilla marmorata and A. biocolor pacifica spawn outside the Indonesian Seas, with A. marmorata recruiting in large numbers in the Sulawesi Island region during much of the year. Other spawning locations of A. celebesensis and A. interioris likely exist in Indonesian waters. Therefore, further research is needed to understand the reproductive ecologies and biodiversity of the tropical anguillid eels in each region of Indonesia in relation to geographic and climatic factors.

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Distinct Size and Distribution Patterns of the Sand-sifting Sea Star, Archaster typicus, in an Urbanised Marine Environment

Archaster typicus is a microphagous sea star ubiquitous throughout sandy shoals of the Indo-Pacific. Along highly urbanised coasts, loss of sandy habitats through land reclamation and degradation of adjacent mangrove forests and seagrass meadows, which serve as nurseries for A. typicus, could lead to local extinction of this species. To determine the population status of A. typicus in Singapore, we performed belt-transect surveys at three modified shores, then compared size structure, clustering patterns and ontogenetic shifts within the Central Indo-Pacific region. We found that A. typicus individuals were, among other things, larger in Singapore (79.2 ± 14.2 mm) than the rest of the Central Indo-Pacific region with further differences amongst Singapore's sites. Sea stars of this species were also greatly clustered in smaller areas within the transects, with most transects presenting small Nearest Neighbour Index values of ＜ 1. While ontogenetic shifts were noted in previous studies, no juveniles have been recorded in the nursery habitats of mangroves and seagrasses, with limited size and mating seasonalities. Although A. typicus appears to have grown in size considerably on reclaimed beaches in Singapore, the lack of any apparent ontogenetic connectivity here may threaten the sea star populations in the near future, particularly in the context of growing coastal development in Southeast Asia.

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Validation of Male Pontella spinipes Giesbrecht, 1889 (Copepoda: Calanoida: Pontellidae) Based on Morphological and Mitochondrial COI Gene Sequence Analysis

The neustonic copepods of the family Pontellidae - Pontella spinipes Giesbrecht, 1889 and P. diagonalis Wilson, 1950, both first described on the basis of female specimens exhibit very similar morphology and overlapping geographic ranges in the Indian Ocean. While several taxonomists have described males of each species, there has been no definitive evidence for female-male matching (link female and male of the same species) in the two species. In the present study, an analysis of mitochondrial cytochrome c oxidase subunit I (mtCOI) sequences in the specimens collected from the Arabian Sea revealed that female P. spinipes Giesbrecht, 1889, and male P. diagonalis sensu Silas and Pillai (1973) are genetically identical, providing evidence that the latter is actually P. spinipes. These findings emphasize that it is necessary to re-examine the female-male correspondence of other related species, formerly based on morphology alone, using molecular-genetic analysis as applied in the present study.