Marratha angusta (Rathbun, 1906) Ng & Clark, 2003

Ng, Peter K. L. & Clark, Paul F., 2003, Three new genera of Indo-West Pacific Xanthidae (Crustacea, Decapoda, Brachyura, Xanthoidea), Zoosystema 25 (1), pp. 131-147 : 134-136

Marratha angusta (Rathbun, 1906) n. comb.

( Figs 1A ; 2 A-E) Cycloxanthops angustus Rathbun, 1906: 849 , textfig. 13, pl. 9 fig. 6; 1911: 217. — Edmondson 1962: 233, fig. 4b-d. — Guinot 1967b: 262. Neoxanthops ? angustus – Serène 1968: 78.

Aff. Neoxanthops angustus – Serène 1984: 212, fig. 128bis, pl. 29E.

TYPE MATERIAL. — Hawaii. Southeast coast of Molokai, Albatross, stn 3850, 23-66 fathoms, 1

cl 8.8 mm, cw 11.6 mm, holotype ( USNM 29453b). — Auau Channel, Albatross, stn 3847, 21- 28 fathoms, 1 cl 7.8 mm, cw 10.9 mm, paratype ( USNM).

OTHER MATERIAL EXAMINED. — South China Sea. Macclesfield Bank, HMS Penguin , c. 15°50’N, 114°20’E, 1 cl 7.2 mm, cw 8.6 mm, det. D. Guinot 1967, pres. Lords of the Admiralty ( NHM 1967.5.3.1.1).

Hawaii. Waikiki, Oahu , 12.IX.1963, coll. D. P. Fellows, 1 cl 7.7 mm, cw 10.8 mm ( ZRC ex BPBM-S 6905 ). — King Expedition, stn 195, 1959, 1 cl 7.9 mm, cw 11.0 mm ( BPBM-S 6815 ) ; stn 238, 1959, 1 (broken) cl 4.4 mm, cw 6.7 mm ( BPBM-S 6621 ). — Brock Expedition , “Mala No. 2”, 2.I.1949, 1 cl 7.8 mm, cw 10.8 mm ( BPBM-S 5511 ) .

DISTRIBUTION. — Amirantes ( Guinot 1967b); Hawaii (Rathbun 1906; Edmondson 1962; Serène 1984); South China Sea (present study).

DESCRIPTION

Carapace quadrate, wider than broad; dorsal surface appears rough, all regions appears swollen, covered with granules, those on 2M and 3M arranged in uneven transverse rows. Front produced, separated into two broad lobes by prominent V-shaped cleft, margin of each lobe serrulate, with two or three spinules longer than rest, uneven to sinuous; separated from acutely triangular inner supraorbital tooth by deep V-shaped cleft, margins granulate to gently serrulate; orbits subparallel with frontal margin, lined with small granules, those on submedian part sharper, dentiform. External orbital tooth acutely triangular, sharp, confluent with subcristate anterolateral margin; anterolateral margin arcuate, with four low but prominent cristate lobes, first low, smallest, second and third lobes broad, fourth lobe small, almost dentiform, directed laterally; margins of all lobes prominently granular, saw-like. Posterolateral margin gently convex to almost straight, lined with tubercles. Posterior carapace margin gently convex, subequal in length to frontal margin, surface rugose. Subhepatic, suborbital and sub-branchial regions granular, covered with scattered long, soft setae which partially obscures surface. Infraorbital margin granular, without clefts. Eyestalk with four or five relatively larger granules at dorsal junction of cornea. Basal antennal segment stout, subrectangular, closing orbital hiatus, with short flagellum entering orbit. Antennules folding laterally; fossa relatively large. Endostomial ridges not discernible. Surface of third maxilliped with scattered granular, denser at distal end of merus; merus squarish, anteroexternal angle not auriculiform; ischium elongate, rectangular, with shallow but clearly visible oblique median sulcus; exopod relatively broad, not reaching anterior edge of merus, with well-developed flagellum.

Chelipeds elongate, relatively slender; all outer surfaces granular, appears very rough, somewhat eroded especially on inner surface, which has prominent uneven tranverse depressions. Dorsal margin of merus granular, without obvious tooth. Carpus rounded, inner angle with one prominent sharp tooth and several tubercles anterior to and uneven granules posterior to it, outer angle conspicuously rounded, forming prominent bulge, margin posterior to it covered with sharp granules. Chela with inner surface prominently rugose; fingers slender, long, shorter than palm, tips sharp; palm without obvious crest, longitudinal depression evident from dorsal view; outer surface granular, especially on proximal surfaces. Major (usually right) chela with two or three teeth and pronounced broad molariform basal tooth on cutting edge of dactylus; cutting edge of pollex with three or four teeth; dorsal margin of dactylus tricarinate, median carina highest with proximal part cristiform. Minor (usually left) chela with fingers more slender, cutting edges blade-like, with two or three teeth and two or three denticles each. Ambulatory legs with merus not cristate, dorsal margin serrulate; carpus with distal part of dorsal margin subcristate, produced into rounded tooth, margin unevenly serrulate, lined with soft setae which partially obscures margins.

Thoracic sternum relatively broad, surface relatively smooth; suture between sternites 1 and 2 not discernible; suture between sternites 2 and 3 well-developed, complete medium part shallower; suture between sternites 3 and 4 prominent but interrupted medially; sutures between sternites 4 and 5, 5 and 6, and 6 and 7 incomplete; abdomen reaching to imaginary line joining median part of bases of chelipeds. Male gonopore coxal, conceled and opening below abdominal segment 3.

Abdomen with segments 3-5 completely fused, sutures separating segments not discernible, lateral margins entire, without clefts; segments 1-3 trapezoidal, segment 6 squarish, lateral margins straight and parallel to gently concave; telson semicircular, lateral margins convex, tip rounded; surfaces of all segments finely granular.

G1 relatively stout, distal part gently curving outwards, tapering to rounded, slightly flared tip; lateral margins lined with short spines and long plumose setae on dorsal margin. G2 short, slen- der, distal part with subpetaloid process.

REMARKS

Rathbun (1906) described Cycloxanthops angustus on the basis of one holotype female and one paratype male from the southern coast of Molokai in Hawaii. It has since been reported from various parts of the Indo-West Pacific. The present series of specimens are remarkably consistent in the various characters described although they originate from a very large area in the Indo- West Pacific. The G1 structures of this species, first figured by Serène (1984), agree with those from Hawaii in all key aspects.

Figures

FIG. 1. — A, Marratha angusta (Rathbun, 1906) n. comb., cl 7.2 mm, cw 8.6 mm, Macclesfield Bank, c. 15°50’N, 114°20’E, South China Sea, HMS Penguin, det. D. Guinot 1967, pres. Lords of the Admiralty (NHM 1967.5.3.1.1); B, Jacforus cavatus (Rathbun, 1907) n. comb., cl 5.7 mm, cw 8.3 mm, NW Island, Capricorn Group, Queensland, Australia, coll. and det. M. Ward (NHM 1931.4.14.17); C, Danielea noelensis (Ward, 1934) n. comb., holotype cl 6.4 mm, cw 4 mm, Christmas Island, pres. Raffles Museum (NHM 1935.5.21.9).

FIG. 2. — Marratha angusta (Rathbun, 1906) n. comb., cl 7.7 mm, cw 10.8 mm (ZRC, ex BPBM-S 6905), Hawaii; A, orbit and antennae; B, anterior thoracic sternites; C, left third maxilliped (setae not drawn); D, abdomen; E, left pleopod 1; F, distal part of pleopod 1 (after Serène 1984). For all structures, minute granules not drawn. Scale bar: A-D, 1.0 mm; E, 0.5 mm.