New records of two decapod crustaceans (Decapoda: Dendrobranchiata and Pleocyemata) from the Gulf of Mannar, India

Abstract

The coral reefs and deep water ecosystems of the Gulf of Mannar support a wide array of decapod crustacean cryptofauna. However, inadequate faunistic surveys and taxonomic expertise have hindered their documentation. Twenty-three bottom trawl hauls taken on-board commercial single-day otter trawlers operating bottom trawls at 16–153 m depths in the Gulf of Mannar, and by-catch dumps at Tuticorin Fishing Harbour were examined during 2012–2013. These surveys revealed first records of the penaeid prawn, Metapenaeopsis tarawensis Racek and Dall, 1965 and the brachyuran crab, Xenophthalmus wolfii Takeda and Miyake, 1970, from Indian seas. Metapenaeopsis tarawensis is distinguished by the absence of stridulating ridge on the carapace, and the presence of a short distal projection on the right petasmal valve inserted perpendicularly to its axis, entirely concealed by left petasmal valve. Xenophthalmus wolfii is distinguished by longitudinal orbits, rudimentary cornea, presence of triangular patch of granules at the lateral constriction with extensions along lateral margins, and apically denticulate, narrow distal process of first gonopod with varied spines at its base. Xenophthalmus wolfii is previously reported from Iran, Bahrain and Pakistan coasts, thereby indicating its eastward range extension. The paper provides illustrated descriptions of these specimens, comparisons with descriptions of type specimens as well as taxonomic comparisons with closely related species.