Rapipontonia Marin, 2007

Marin, Ivan, 2009, A review of the pontoniine shrimp genus Rapipontonia Marin, 2007 (Decapoda: Caridea: Palaemonidae), with the description of a new species from the Indo-West Pacific, Zootaxa 2289, pp. 1-17 : 2-3

Rapipontonia Marin, 2007

Type species. Rapipontonia paragalene Marin, 2007

Species included. Rapipontonia platalea (Holthuis, 1951) , R. galene ( Holthuis, 1952) , R. paragalene Marin, 2007 , R. hydra n. sp.

Diagnosis. Medium-sized pontoniine shrimps with slender body. Carapace smooth, with antennal, hepatic and epigastric teeth; hepatic tooth situated posterior and slightly above level of antennal tooth; epigastric spine well marked, smaller than proximal dorsal rostral tooth, clearly separated from rostral teeth, divided from carapace by a suture. Rostrum long and slender, with well developed proximal dorsal carina bearing 4–5 teeth and slender distal part bearing small dorsal and subapical teeth; ventral margin unarmed. Inferior orbital angle produced, bluntly rounded. Abdomen smooth, third tergite non-carinate or posteriorly produced; pleura posteroventrally rounded. Telson slender, tapering distally, with two pairs of small dorsal spines and three pairs of posterior marginal spines. Ophthalmic somite without intraocular beak. Fourth thoracic sternite without finger-like median process, fifth to eighth unarmed. Eyes with globular cornea. Antennula normal, basal segment with distolateral margin bearing sharp slender distolateral tooth and bluntly produce median lobe. Antenna normal, without special features, scaphocerite well developed. Epistome unarmed. Mandible without palp. Maxillula with bilobed, unsetose palp, well developed upper and lower lacinia. Maxilla with slender palp, well developed scaphognathite, basal endite well developed, simple; coxal endite lacking. First maxilliped with simple palp, basal endite broad, coxal endite smaller, exopod and caridean lobe well developed, epipod bilobed. Second maxilliped with non-modified endopod, exopod as in first maxilliped, epipod small, simple, without podobranch. Third maxilliped with slender segments, ischiomerus and basis fused, with distinct suture, exopod well developed, coxa with rounded lateral plate, single small arthrobranch and several long, plumose setae. First pereiopods slender, fingers simple, with spoon-like tips. Second pereiopods equal or unequal in size and shape in females and always equal in males; segments slender, unarmed; fingers simple, with well straight cutting edges, without molar process and fossa. Ambulatory pereiopods slender, propodus with 2 or 3 long unpaired ventral spines situated in distal third of propodus and a pair of large distoventral spines situated on considerable distance proximally to distoventral margin of propodus; distoventrally accompanied with plumose setae; dactyls simple, long, slender, curved. Pleopods normal; endopod of male first pleopod simple, ovate; endopod of male second pleopod with appendix interna bearing terminal cincinnuli, appendix masculina with 1–2 terminal serrated setae and 2–3 simple setae along lateral margin Uropods slender, without specific features, with distolateral margin bearing small fixed distolateral tooth and movable simple spine.

Differential diagnosis. Genus Rapipontonia clearly differs from other pontoniine genera by the presence of a unique structure of grasping (prehensile) mechanism on the ambulatory pereiopods consisting of long curved simple dactylus, 2–3 unpaired, closely spaced long spines situated in distal third of ventral margin of propodus and a pair of long distoventral spines on oblique ventral margin of distally tapering propodus. A pair of distoventral ventral spines is situated some distance proximal to distoventral margin of propodus that is also unique within the subfamily. For other diagnostic features of the genus see its original description ( Marin, 2007).

Distribution. The representatives of the genus have been found throughout numerous localities: Indian Ocean ( R. galene ) ( Bruce, 1976; Fransen, 1994; present study), the West Pacific ( R. galene , R. paragalene , R. hydra n. sp.) ( Holthuis, 1952; Bruce & Coombes, 1995; Bruce, 1996; Marin, 2007; present study), Hawaii ( R. galene , see below), the western ( Tobago) and the eastern Atlantic ( R. platalea ) ( Cape Verde Island, São Tomé and Guinea) (Holthuis, 1951; Wirtz & d’Udekem d’Acoz, 2001; Wirtz, 2003; Hale & De Grave, 2007; present study).