Rapipontonia platalea (Holthuis, 1951)

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 : 3-6

Rapipontonia platalea (Holthuis, 1951)

( Figs 1 , 2 )

Periclimenes platalea Holthuis, 1951: 157 , fig. 32 [type locality – off Guinea]. Periclimenes platalea . — Hale & De Grave, 2007: 1019.

Rapipontonia platalea .— Marin, 2007: 777.

Material. 2 females, 2 male ( RMNH D51044), tropical eastern Atlantic, Cape Verde Islands, Sao Nocolau, SE coast, “Tyderman”, Cancap VII, Cape Verde Islands Exp., Sta 7. D.11, 16º34’N 24º17’W, 2/ 3Sept. 1986; 2 males ( RMNH D50048), tropical eastern Atlantic, São Tomé, Pedra Hirondino, Rolas Island, 0ºN, 6º31’E; from gorgonians, 14 m, Aug. 2002, coll. P.Wirtz; 2 males ( RMNH D50047), Tropical eastern Atlantic, São Tomé, Pedra de Brago, Rolas Island, from gorgonians, 12 m, Aug. 2002, coll. P. Wirtz.

Diagnosis. Epigastric tooth clearly divided from carapace by suture. Rostrum slender, rostral formula 1+6–7/0; proximal rostral crest with 4–5 large teeth; distal part of rostrum short, with one small dorsal and tiny subapical teeth, without distinct gap between second and most distal teeth in rostral series. Antenna with distolateral margin of basal segment bearing sharp distolateral tooth and bluntly triangular median lobe. First pereiopod slender, fingers with spoon-like tips. Second pereiopods slender, equal in males and unequal in females. In females, major second pereiopod with carpus about 1.5 times shorter than propodus, fingers about 3.5 times shorter than palm length; minor second pereiopod with carpus about twice longer than propodus, fingers about 1.3 times longer than palm. In males, carpus of second pereiopod is about 1.3 times longer than palm, fingers about twice shorter than palm length. Third pereiopod with distoventral margin of propodus bearing 2-3 unpaired and a pair of long distoventral spines; most proximal third unpaired spine, if present, about half length of next one.

Remarks. Smallest species within the genus. The species clearly differs from the remaining species within the genus by shorter rostrum, reaching to the middle of intermediate segment of antennular peduncle in females, and geographically occurring in the Atlantic Ocean.

Coloration. Mainly transparent with reddish stripes and small white spots; distal segments of second pereiopods, antennular peduncle stalk, distoventral margin of pleura and proximal margin of telson are reddish-yellow; broad red band crossing along the ventral surface of the body from antennular peduncle to the midlength of the abdomen; cornea of eyes white; white small spots situated along dorsal surface of carapace and abdomen.

Hosts and distribution. The species is known from the western ( Tobago ( Hale & De Grave, 2007)) and the eastern ( Cape Verde Islands, São Tomé and Guinea (Holthuis, 1951; Wirtz & d’Udekem d’Acoz, 2001; Wirtz, 2003; present study)) Atlantic Ocean. Associated with the hydroid, Gymnangium longicauda (Nutting, 1900) (Cnidaria: Hydrozoa), encrusted with Parazoanthus tunicans Duerden, 1900 ( Hale & De Grave, 2007) , Antipathes spp. (Cnidaria: Antipatharia ) ( Wirtz & d’Udekem d’Acoz, 2001) and Leptogorgia gaini Stiasny, 1940 ( Wirtz & d’Udekem d’Acoz, 2001) and Leptogorgia sp. (Cnidaria: Gorgonacea) ( Wirtz, 2003).

Figures

FIGURE 1. Rapipontonia platalea (Holthuis, 1951), female (A, B, E-H), male (C, D) (RMNH, D 51044): A, Ccarapace and frontal appendages in lateral view; B, D—carapace, lateral view; E—basal segment of antennula; F—third maxilliped; G, H—grasping mechanism of third pereiopod. Scale bar: 1 mm.

FIGURE 2. Rapipontonia platalea (Holthuis, 1951), female (A, E - H), male (B - D) (RMNH, D 51044): A—chela of first pereiopod; B, C—second pereiopods of male; D—same, chela; E—major second pereiopod; F—same, chela; Gminor second pereiopod; H—same, chela. Scale bar: 1 mm.