A further record of the rare hippolytid shrimp Leontocaris lar Kemp, 1906 (Decapoda, Caridea) from the Celtic Sea, off north-western France

Abstract

Members of the deep-sea caridean shrimp genus Leontocaris Stebbing, 1905 (family Hippolytidae Spence Bate, 1888) have a very peculiar major second cheliped with a massive palm bearing a tympanum and a blade-like dactylus, probably related to an as yet unknown predatory behaviour (Taylor & Poore, 1998; Fransen, 2001; Poore, 2009). Currently nine species are known in the genus (De Grave & Fransen, 2011; Cardoso & Fransen, 2012). In North Atlantic waters only one species, Leontocaris lar Kemp, 1906 has been reported and up to now, remains only known from three specimens collected off Ireland more than a century ago (Kemp, 1906, 1910; d’Udekem d’Acoz, 1999). The rarity of this species, and indeed all known species in the genus, is likely due to these shrimps inhabiting deep-sea coralline habitats, which are very difficult to sample by conventional means (Kemp, 1906, 1910; Taylor & Poore, 1998; Fransen, 2001; Poore, 2009; Ahyong, 2010; Cardoso & Fransen, 2012). In 2011, during a ROV “Victor6000” dive of the “BobEco” cruise carried out on board the RV “Pourquoi Pas?” (chief scientist: S. Arnaud-Haond, Ifremer), a further specimen was collected in the Celtic Sea off north-western France, allowing for a better understanding on the characteristics and ecology of this rare species. In situ observation of L. lar confirms for the first time its association with antipatharian corals. A close examination of the present specimen reveals that the recently described Leontocaris smarensis Cardoso & Fransen, 2012, from the South Mid-Atlantic Ridge is extremely similar to L. lar, potentially being a synonym of L. lar.

The specimen described in this work is deposited in the collection of the Muséum National d’Histoire Naturelle, Paris (MNHN). Carapace length (cl) is measured dorsally from the posterior part of the orbit to the posterior margin of the carapace.