Paradynomene tuberculata Sakai, 1963

Mclay, Colin L. & Ng, Peter K. L., 2004, A taxonomic revision of the genus Paradynomene Sakai, 1963 (Crustacea: Decapoda: Brachyura: Dynomenidae), Zootaxa 657, pp. 1-24 : 4-8

Paradynomene tuberculata Sakai, 1963 ( Figs. 2 , 3 , 4 , 14 A)

Paradynomene tuberculata Sakai, 1963: 231 , fig. 8;— Sakai 1965: 13, pl. 6, fig. 1; 1976: 31, pl. 7, fig. 1;— Serène 1968: 37 (list);— Miyake 1983: 196 (list);— Nagai 1989: 43;— McLay 1999: 543 (part), fig. 25d.

Material. Holotype male, 9.5 x 10.5 mm, Sagami Bay, 85 m, Emperor’s Collection ( NSMT). Others: 2 males, 18.2 x 18.5 mm, 18.1 x 18.1 mm, Balicasag Island, Panglao, Bohol, Visayas, Philippine Islands, in tangle nets, 200–300 m, coll. local shell fishermen, Dec 2000 ( ZRC 2001.361); 1 male, 22.5 x 23.4 mm, Balicasag Island, Panglao, Bohol, Visayas, Philippines, in tangle nets, 200–300 m, coll. local shell fishermen, 25–30 Jul 2003 ( ZRC); 1 male, 21.5 x 22.3 mm, 1 female, 21.5 x 21.2 mm, station DW 406, 20°40.65'S, 167°06.80'E, 373 m, Loyalty Islands, coll. MUSORSTOM 6, 15 Feb 1989 (MNHN­B25249, MNHN­B26603,).

Description. Carapace sub­rectangular, width similar to length, margins sub­parallel, surface areolate, covered with pavement of small rounded closely packed granules. Carapace regions well marked. Frontal groove clearly marked, separating pair of small epigastric tubercles, groove dividing posteriorly to define mesogastric area containing median tubercle, with prominent protogastric tubercles on each side. Pair of metagastric tubercles, similar in elevation to mesogastric tubercle, separated by groove. Urogastric area well defined, with 2 tubercles. Cardiac area swollen shallowly divided with 2 weak tubercles, followed by smaller median intestinal tubercle. Branchial area dominated by 4 tubercles: 1 epibranchial tubercle, 1 mesobranchial tubercle, 2 smaller metabranchial tubercles. Total of 20 areolate tubercles on whole carapace: 8 on each side, 2 unpaired median tubercles. Each of the tubercles with small group of long filiform setae. Carapace evenly convex in lateral view.

Rostrum projecting, tridentate, lateral teeth small, median tooth longer, directed horizontally, visible dorsally. Two well developed, dorsally directed supraorbital tubercles behind rostrum, rest of orbital margin covered with small granules, prominent suborbital tubercle visible dorsally. Orbits obliquely arranged, clearly exposed dorsally.

Anterolateral margin begins below level of postorbital corner armed with 6 teeth of variable size, fourth, sixth largest. First anterolateral tooth preceded by 2 small, closely spaced sub­hepatic teeth that form anterior corner of carapace. Behind branchial groove are 2 well developed posterolateral teeth, last forming posterior corner of carapace.

Pereopods covered in small granules. Cheliped carpus with small tubercles on inner and outer proximal margins, 3 closely spaced large tubercles along outer distal margin. Propodus with 3 small tubercles along inner, 4 along outer dorsal margins. Fingers not curved downwards, margins close together for most of length, 6 weakly developed teeth on fixed finger, no teeth on moveable finger. At rest, fingers slot in beside bases of third maxillipeds that are covered with dense mass of fine setae. Margins of second to fourth pereopods tuberculate, fifth pereopod reduced, hidden under posterolateral carapace corner in dorsal view.

Surface of abdomen granulate, margins setose, abdomen only loosely held against sternum. No effective abdominal locking mechanism, uropod plates fill about half of lateral margin of sixth segment, adjacent to slightly elevated group of small granules on coxa of second pereopod. Edges of penultimate abdominal segment lie alongside similar group of granules on coxae of third pereopods which restrict lateral movement of abdomen.

Remarks. A re­examination of the specimens listed above, previously reported as Paradynomene tuberculata by McLay (1999), confirm that many do not belong to this species but to the various new species described below. The specimens from the Loyalty Islands ( Fig. 3 B) agree very well with the detailed type description and excellent figure by Sakai (1963). Compared to these, the two males from the Philippine Islands (e.g. Fig. 3 A) are generally less tuberculate, but this is probably due to the granules and tubercles being more worn. The density and positions of the granules and tubercles are identical. All the specimens of this species we have examined have tufts of long setae on some of the larger areolae, a feature absent on the other congeners. The reliability of this character, however, will need to be confirmed with a larger series.

The revised distribution of P. tuberculata restricts the species to Japan, Loyalty Islands ( New Caledonia), and the Philippine Islands. The species can be regarded as a deep­water species. The shallowest they have been recorded from is 85 m (holotype) and the deepest, 402 m. The records shallower than 85 m all belong to P. rotunda n. sp.

Figures

FIGURE 2. Dorsal view Paradynomene tuberculata Sakai, 1963. Holotype male, 9.5 x 10.5 mm, Sagami Bay, Japan 85 m, Emperor’s Collection (NSMT).

FIGURE 3. Dorsal view Paradynomene tuberculata Sakai, 1963 A, male, 18.2 x 18.5 mm, Philippine Islands (ZRC 2001.361); B, male, 21.5 x 22.3 mm, Loyalty Islands (MNHN­B 25249).

FIGURE 4. Paradynomene tuberculata Sakai, 1963. A, male, 18.2 x 18.5 mm,, Philippine Islands (ZRC 2001.361). A, schematic figure of carapace (small granules not drawn); B, schematic lateral view of carapace (small granules not drawn); C, gastric region of carapace showing pattern of granules and setae; D, outer view of right chela; E, dorsal view of right cheliped (small granules not drawn). Scales = 2.0 mm.

FIGURE 14. Frontal views. A, Paradynomene tuberculata Sakai, 1963, male, 21.5 x 22.3 mm, Loyalty Islands (MNHN­B 25249); B, P. quasimodo n. sp., holotype male, 14.3 x 15.4 mm, Philippine Islands (ZRC 2001.360); C, P. d emo n n. sp., holotype female, 23.2 x 24.0 mm,, New Caledonia (MNHN­B 26602); D, P. diablo n. sp., holotype male, 11.4 x 12.6 mm, Norfolk Ridge, New Caledonia (MNHN­B 26607); E, P. t e u f e l n. sp., holotype male 7.8 x 8.6 mm, Gulf of Aden (SMF); F, P. rotunda n. sp., holotype female, 19.0 x 18.0 mm, Chesterfield Islands (MNHN­B 26604).