During the past decade, a large number of multi-gene analyses aimed at resolving the phylogeneticrelationships within Decapoda. However relationships among families, and even among sub-families, remain poorly defined. Most analyses used an incomplete and opportunistic sampling of species, but also an incomplete and opportunistic gene selection among those available for Decapoda. Here we test in the Caridea if improving the taxonomic coverage following the hierarchical scheme of the classification, as it is currently accepted, provides a better phylogenetic resolution for the inter-families relationships. The rich collections of the Muse´um National d’Histoire Naturelle de Paris are used for sampling as far as possible at least two species of two different genera for each family or subfamily. All potential markers are tested over this sampling. For some coding genes the amplification success varies greatly among taxa and the phylogenetic signal is highly saturated. This result probably explains the taxon-heterogeneity among previously published studies. The analysis is thus restricted to the genes homogeneously amplified over the whole sampling. Thanks to the taxonomic sampling scheme the monophyly of most families is confirmed. However the genes commonly used in Decapoda appear non-adapted for clarifying inter-families relationships, which remain poorly resolved. Genome-wide analyses, like transcriptome-based exon capture facilitated by the new generation sequencing methods might provide a sounder approach to resolve deep and rapid radiations like the Caridea.

Restreint, ATIMO VATAE, Restreint, Restreint, BATHUS 1, BATHUS 3, BATHUS 4, BENTHAUS, BERYX 11, BERYX 2, BIOCAL, Restreint, BIOPAPUA, Restreint, Restreint, Restreint, Restreint, Restreint, Restreint, HALIPRO 1, HALIPRO 2, Restreint, KARUBAR, Restreint, LAGON, MAINBAZA, MD08 (BENTHOS), MD20 (SAFARI), MIRIKY, MUSORSTOM 2, MUSORSTOM 3, MUSORSTOM 5, MUSORSTOM 9, NORFOLK 1, NORFOLK 2, SALOMON 2, SALOMONBOA 3, SANTO 2006, SMCB

BOA1, SANTO 2006

Although most chitons (Mollusca: Polyplacophora) are shallow-water molluscs, diverse species also occur in deep-sea habitats. We investigated the feeding strategies of two species, Leptochiton boucheti and Nierstraszella lineata, recovered on sunken wood sampled in the western Pacific, close to the Vanuatu Islands. The two species display distinctly different associations with bacterial partners. Leptochiton boucheti harbours Mollicutes in regions of its gut epithelium and has no abundant bacterium associated with its gill. Nierstraszella lineata displays no dense gut-associated bacteria, but harbours bacterial filaments attached to its gill epithelium, related to the Deltaproteobacteria symbionts found in gills of the wood-eating limpet Pectinodonta sp. Stable carbon and nitrogen isotope signatures and an absence of cellulolytic activity give evidence against a direct wood-feeding diet; both species are secondary consumers within the wood food web. We suggest that the distinct associations with bacterial partners are linked to niche specialisations of the two species. Nierstraszella lineata is in a taxonomic family restricted to sunken wood and is possibly adapted to more anoxic conditions thanks to its gill-associated bacteria. Leptochiton boucheti is phylogenetically more proximate to an ancestral form not specialised on wood and may itself be more of a generalist; this observation is congruent with its association with Mollicutes, a bacterial clade comprising gutassociated bacteria occurring in several metazoan phyla

SANTO 2006

A new genus of a deep-sea ascomycete with one new species, Alisea longicolla, is described based on analyses of 18S and 28S rDNA sequences and morphological characters. A. longicolla was found together with oceanitis scuticella, on small twigs and sugar cane debris trawled from the bottom of the Pacific Ocean off Vanuatu Islands. Molecular and morphological characters indicate that both fungi are members of Holosphaeriaceae. Within this family, O. scuticella is phylogenetically related to Ascosalsum and shares similar ascospore morphology and appendage ontogeny. The genus Ascosalsum is considered congeneric with Oceanitis and Ascosalsum cincinnatulum, Ascosalsum unicaudatum and Ascosalsum viscidulum are transferred to Oceanitis, an earlier generic name. (C) 2009 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

BOA0

Wood falls in the deep sea have recently become the focus of studies showing their importance as nutrients on the deep-sea floor. In such environments, Crustaceans constitute numerically the second-largest group after Mollusks. Many questions have arisen regarding their trophic role therein. A careful examination of the feeding appendages, gut contents, and gut lining of Munidopsis andamanica caught with wood falls revealed this species as a truly original detritivorous species using wood and the biofilm covering it as two main food sources. Comparing individuals from other geographic areas from substrates not reported highlights the galatheid crab as specialist of refractory substrates, especially vegetal remains. M. andamanica also exhibits a resident gut microflora consisting of bacteria and fungi possibly involved in the digestion of wood fragments. The results suggest that Crustaceans could be full-fledged actors in the food chains of sunken-wood ecosystems and that feeding habits of some squat lobsters could be different than scavenging.

BOA1, KARUBAR, MUSORSTOM 10, MUSORSTOM 3, SALOMONBOA 3, SANTO 2006

Squat lobsters of the deep-sea genus Munidopsis are among the most regularly reported crustaceans associated with deep-sea wood falls. They are often thought to indirectly use these substrates for preying or scavenging wood-associated molluscs or annelids, albeit the species M. andamanica has been recently highlighted as a xylophagous specialist. In this work, we examined the feeding appendages, gut contents and gut lining of M. nitida, M. bispinoculata and M. pilosa specimens from natural sunken woods and compared them with specimens of the same species having survived and grown on different hard-to-digest substrates (i.e. woods, turtle shells and whale bones) experimentally submerged in the deep South Pacific. In both cases, all three species directly ingest large wood fragments deeply degraded by microorganisms, but M. nitida also feeds on experimentally submerged whale bone and turtle shell fragments. Munidopsis nitida is also the only species to host a resident gut microflora, but the bacterial morphotypes vary according to the ingested substrate. The results suggest that the three species are most probably opportunistic, bacterivorous detritivores and that M. nitida could be at the beginning of an evolutionary process towards xylophagy within the genus Munidopsis.

BOA1, CONCALIS, Restreint, SALOMONBOA 3, SANTO 2006

Sunken woods are abundant in deep oceanic environments, housing a huge faunal diversity. Studies on that substrate firstly focused on the associated organisms, but since a few years, identification of wood is a further aim. The purpose is to appreciate its degradation state, diversity, geographical origin and to identify specific associations between colonizing organisms and substrates. The first determinations were made on sunken woods from Taiwan/Philippines, the Vanuatu Archipelago, and the Mediterranean Sea. Samples' identification was based on histological studies. Different preparation techniques were used, depending on their degradation state. Detailed anatomy descriptions were made and compared to the native flora and the introduced species. Wood samples were well preserved. Diversified species were encountered, seemingly originating from local floras. In situ settlements of known wood species will enhance the knowledge of degradation and colonization degrees.

BOA0, MUSORSTOM 3, TAIWAN 2002

BOA0, SANTO 2006

When deposited in marine sediments, sunken wood and large animal remains can undergo sufficiently steady decay for oxygen to be depleted, attracting anaerobic living forms. Chemosynthetically living communities have recently been identified around whale skeletons and sunken woods. The phylogenetic resemblance and overlap in species of metazoans living in these habitats with those of highly reduced environments like hydrothermal vents and vent seeps has led to the hypothesis that deep-sea organic rich matter deposits could play a major role in the adaptation and evolution of chemoautotrophic communities at the ocean basin. Until present little attention has been paid to the free-living microbial diversity and activities in large organic falls like sunken woods and whale bones. In this communication we outline a series of methods to quantitatively study microbial biodiversity and degradation processes in sunken wood. Cellulose is the most abundant component of plant material and it can only be degraded by fungi and bacteria. We present results from cellulolytic activities in a long-term ex-situ experiment on samples from naturally and experimentally immersed sunken wood. We also have developed methods to quantitatively measure microbial cell numbers in wood chips. Further studies at the molecular level in combination with the methods reported here will broad our narrow knowledge on the microbial biofilms that develop on and within sunken woods and give clues on the ecological importance of these deep-sea organic islands.

BOA0

BOA0

Even though their occurrence was reported a long time ago, sunken wood ecosystems at the deep-sea floor have only recently received specific attention. Accumulations of wood fragments in the deep sea create niches for a diverse fauna, but the significance of the wood itself as a food source remains to be evaluated. Pectinodonta sp. is a patellogastropod that exclusively occurs on woody substrates, where individuals excavate deep depressions, and is thus a potential candidate for a wood-eating lifestyle. Several approaches were used on Pectinodonta sampled close to Tongoa island (Vanuatu) to investigate its dietary habits. Host carbon is most likely derived from the wood material based on stable isotopes analyses, and high cellulase activity was measured in the digestive mass. Electron microscopy and FISH revealed the occurrence of two distinct and dense bacterial communities, in the digestive gland and on the gill. Gland-associated 16S rRNA gene bacterial phylotypes, confirmed by in situ hybridization, included members of three divisions (Alpha- and Gammaproteobacteria, Bacteroidetes), and were moderately related (90-96% sequence identity) to polymer-degrading and denitrifying bacteria. Gill-associated phylotypes included representatives of the Delta- and Epsilonproteobacteria. The possible involvement of these two bacterial communities in wood utilization by Pectinodonta sp. is discussed.

BOA0, BOA1, SANTO 2006