Opaepupu, a new genus and species of bivalve-associated shrimp (Decapoda: Caridea: Palaemonidae) from Hawai'i.

A new palaemonid shrimp genus, Opaepupu gen. nov., is established to accommodate a new species of bivalve-associated shrimp, Opaepupu huna sp. nov. from Hawaii. A single mated pair, the female holotype and the male allotype, were found inside the trapezid bivalve Trapezium oblongum (Linnaeus, 1758) at a depth of 14 m in Kâne'ohe Bay, Hawai'i. The new genus is characterised by the rostrum being proximally broad, distally pointed, mid-dorsally carinate, and non-dentate; the anterolateral margin of the carapace without supraorbital, hepatic or epigastric teeth, but with a strong sharp antennal tooth; the sixth pleonite posteriorly unarmed; the telson medially depressed, with the dorsal surface armed with two pairs of submarginal cuspidate setae and with the posterior margin armed with two pairs of spiniform setae; the distolateral angle of the first article of the antennular peduncle without a sharp tooth; the mandible without a palp; the maxillular palp furnished with one long stiff seta dorsal to a small tooth-like extension; the first maxilliped without a palp; the third maxilliped not being operculate; the second pereiopods moderately robust, relatively slender, subequal, subsymmetrical, with simple teeth on the cutting edges of the fingers; the ambulatory pereiopods being slender, each ending in an elongate biunguiculate dactylus; and the uropodal exopod with a faint diaeresis and greatly reduced distolateral spiniform seta. The phylogenetic position of Opaepupu gen. nov. remains unclear, although it does not appear to be closely related to other bivalve-associated palaemonid genera.

The discovery of Euryrhynchidae (Crustacea: Decapoda) in India, with the description of a new genus and species.

A new genus and species of Euryrhynchidae is described from Kerala, India. This freshwater shrimp family was previously only known from northern South America and West Africa. Although the inclusion of the genus in Euryrhynchidae is unequivocal (e.g. shape of the accessory ramus of the antennular flagellum, frontal margin of the carapace, telson ornamentation), the presence of a number of unique characters makes the relative placement of the genus within the family unclear, but likely basal to the other genera. The new genus can be easily distinguished from all others within the family by these characters, e.g. the upper antennular flagellum and its accessory ramus being joined over three divisions, the presence of a reduced carpo-propodal brush and a well-developed branchiostegal groove.

Synalpheus pinkfloydi sp. nov., a new pistol shrimp from the tropical eastern Pacific (Decapoda: Alpheidae).

A new, conspicuously coloured species of the alpheid genus Synalpheus Spence Bate, 1888, is described based on material collected on the Pacific coast of Panama. Synalpheus pinkfloydi sp. nov. is closely related to the western Atlantic S. antillensis Coutière, 1909, the two taxa being transisthmian, cryptic sister species. Both species are characterised by the distal areas of their major and minor chelae coloured in an intense, almost glowing pink-red. The morphological differences between S. pinkfloydi sp. nov. and S. antillensis Coutière, 1909 are subtle, being limited to the slightly different proportions of the merus of both chelipeds, distodorsal armature of the major cheliped merus, relative length of the antennal scaphocerite, and body size. However, they are genetically different with a 10.2% sequence divergence in COI. Based on molecular clock estimates, these transisthmian taxa diverged around 6.8-7.8 mya, i.e. well before the final closure of the Isthmus of Panama 2.5-3 mya.

A note on the correct spelling of the name of the freshwater shrimp Macrobrachium olfersii (Wiegmann, 1836) (Decapoda, Palaemonidae).

Macrobrachium olfersii (Wiegmann, 1836), popularly known as Pitu, Bristled River Shrimp and Buchura River Prawn, is a freshwater shrimp species widespread along the eastern coasts of the Americas. The species can be found from the southeastern United States, where the prawns were introduced (Holthuis & Provenzano, 1970), southwards to Rio Grande do Sul (Brazil), including numerous records in Mexico, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Guyana and Suriname (Holthuis, 1952; Williams, 1984; Melo, 2003; Valencia & Campos, 2007).

Description of Alpheus cedrici sp. n., a strikingly coloured snapping shrimp (Crustacea, Decapoda, Alpheidae) from Ascension Island, central Atlantic Ocean.

Alpheus cedricisp. n. is described based on two specimens collected under rocks while scuba diving off the coast of Ascension Island, central Atlantic Ocean. The new species belongs to the Alpheus macrocheles (Hailstone, 1835) species complex and appears to be most closely related to the eastern-central Atlantic Alpheus macrocheles, the western Atlantic Alpheus amblyonyx Chace, 1972, and the eastern Pacific Alpheus bellimanus Lockington, 1877 and Alpheus rectus Kim & Abele, 1988. However, it differs from all these species by a combination of morphological characters and by a diagnostic and striking colour pattern.