Journal
<div class="rtejustify"><em>Rimicaris chacei </em>Williams and Rona 1986, formerly named as <em>Chorocaris chacei</em>, is a caridean<br />
shrimp living in deep-sea hydrothermal ecosystems. This shrimp is endemic to the Mid<br />
Atlantic Ridge (MAR) and lives at the periphery of aggregates of its well-known congeneric<br />
<em>R. exoculata</em> Williams and Rona 1986. Contrasting with the very dense and mobile clusters</div>
<div class="rtejustify">formed by <em>R. exoculata</em>, <em>R. chacei</em> lives in small groups of several individuals that are not</div>
<div class="rtejustify">very mobile. Although devoid of the characteristic hypertrophied cephalothorax of <em>R. exoculata</em>,<br />
which harbors the ectosymbionts, a microbial community has also been reported in the<br />
cephalothorax of <em>R. chacei</em>. Previous data on morphology, behavior and isotopic values indicate<br />
a diet based on a combination of feeding on its epibiotic bacteria and scavenging or<br />
occasional predation. In this study, our objective was to describe, for the first time, the distribution,<br />
morphology and phylogeny of the microbial communities associated with <em>R. chacei</em>.<br />
This species is significantly less studied than <em>R. exoculata</em>, but nevertheless represents the<br />
only other known example of symbiosis in crustaceans of MAR hydrothermal vent sites.<br />
Microbial communities have been observed at the same locations as in <em>R. exoculata</em><br />
(mouthparts, branchiostegites and digestive tract). However, in <em>R. chacei</em>, the surfaces<br />
occupied by the bacteria are smaller. The main lineages are affiliated to Epsilon and Gammaproteobacteria<br />
in the cephalothorax and to Deferribacteres, Mollicutes, Epsilon and<br />
Gammaproteobacteria in the digestive tract. Comparison with the well-described bacterial<br />
communities of <em>R. exoculata</em> and hypotheses about the role of these communities in <em>R. chacei</em><br />
are discussed.</div>
