Nobiliella jousseaumei ( Nobili, 1905 ) Komatsu & Takeda, 2003

Komatsu, Hironori & Takeda, Masatsune, 2003, A new genus of leucosiid crabs (Crustacea, Decapoda, Brachyura) from the Red Sea, Zoosystema 25 (3), pp. 413-423 : 415-419

Nobiliella jousseaumei ( Nobili, 1905) n. comb.

(Figs 1; 2; 4A-D)

Nursia jousseaumei Nobili, 1905: 398 (type locality: Red Sea and Perim); 1906: 151, pl. 9(4).

TYPE MATERIAL. — Designated here as lectotype series ; Red Sea and Perim, coll. Dr Jousseaume, 1892 ; lectotype, ovig. 6.7 × 7.5 ( MNHN B 17008) ; allolectotype, 5.9 × 6.6 ( MNHN B 28616) ; paralectotypes, 1 5.9 × 6.6, 1 young 5.1 × 5.7, 3 ovig. 6.5 × 7.3-8.2 × 9.4, 2 7.5 × 8.4, 8.2 × 9.4, 5 young

3.8 × 4.3-5.7 × 6.4 ( MNHN B 28617) ; 1 ovig. 6.4 × 7.0 (NSMT-Cr 15530); Obock, 1892, coll. Dr Jousseaume, 1 young 3.6 × 4.0 ( MNHN B 17009). DISTRIBUTION. — Red Sea ; Gulf of Aden-Perim ( Yemen), Obock ( Djibouti) .

REDESCRIPTION

Carapace (Fig. 1A) subcircular in general outline, 1.1 times broader than long, strongly convex dorsally at center of carapace, armed with median and epibranchial ridges, ridges furnished with pearly granules; margin rimmed with bead- ed line except frontal region; upper surface seemingly smooth, but entirely covered with microscopic flat granules. Front moderately produced, concave medially on dorsal surface; margin subtruncate, with median small tooth. Orbit with only one fissure on roof (mesial fissure absent). Mesogastric region longitudinally convex for its broad part, with shallow median groove. Gastrocardiac region prominently raised; gastric region covered with pearly granules on both sides; cardiac region with median prominent tubercle, tubercle marked with several pearly granules. Intestinal region dorsally prominent, with median row of pearly granules, weakly pointed and marked with some pearly granules around apex. Hepatic region weakly demarcated; margin slightly concave inwards, separated from epibranchial margin by small V-shaped notch; hepatic facet developed, medially concave, with horizontal suture along ventral third. Pterygostomian margin ventrally projecting, concealed beneath hepatic region at posterior end. Epibranchial region sloping anteriorly from epibranchial ridge; margin thin, weakly upturned, roundly convex antero-laterally; epibranchial ridge conspicuous, obliquely extending from near gastric granules to triangular tooth of metabranchial margin, furnished with pearly granules; metabranchial region deeply concave between epibranchial ridge and median elevation; margin almost straight, converging, thin, with small triangular tooth at anterior end. Posterior margin weakly trilobate, thin; median tooth broadest; lateral lobe continuous to metabranchial margin.

Ocular peduncle (Fig. 1B) short; antero-dorsal extension onto cornea rectangular with rounded tip. Antennule somewhat obliquely folded in fossa, basal segment concealed. Basal segment of antenna transversely ovate; second segment triangularly subsquamate, fused with infraorbital lobe, but separated by shallow groove, sparsely covered with microscopic granules. Afferent channel with weak oblique ridge, with short setae along ridge; lateral margin with V-shaped notch near anterior end.

Mandible (Fig. 2A, B) well calcified; cutting edge triangular in outline, pointed medially, finely

FIG. 1. — Nobiliella jousseaumei ( Nobili, 1905) n. comb.; A -C, F, lectotype, ovig. 6.7 × 7.5 mm ( MNHN B 17008) from Red Sea and Perim ; D, E, G -I, allolectotype, 5.9 × 6.6 mm ( MNHN B 28616) from Red Sea and Perim ; A, carapace, dorsal view; B, frontal region, frontal view; C, right third ambulatory leg, dorsal view; D, male sternites, ventral view; E, male abdomen, ventral view; F, female abdomen, ventral view; G, right first male pleopod, external view; H, same, internal view; I, right second male pleopod, external view. Scale bars: A, D, 2 mm; B, 0.5 mm; C, E-I, 1 mm.

dentate on anterior 0.2; endopod palp threesegmented; terminal segment fringed with short setae. Maxillule (Fig. 2C): coxal endite subcylindrical, directed mesially, with some terminal setae; basial endite triangular, with stout setae and thin setae on mesial margin; endopod reduc- ed. Maxilla (Fig. 2D): coxal and basial endites and endopod missing; exopod (scaphognathite) longitudinally expanded into ovate structure, entirely fringed with short plumose setae. First maxilliped (Fig. 2E): coxal endite semiglobular, with dense plumose setae; basial endite lobular, expanded into triangular structure, fringed with long plumose setae; endopod lobular, longitudinally expanded, fitting in efferent channel, highly plicate on upper surface, with long setae along plication; anterior margin of endopod fringed with short plumose setae; exopod reduced, about half as long as endopod, filiform, with some subterminal, long plumose setae, without flagellum. Second maxilliped (Fig. 2F): ischium with long plumose setae along inner margin; merus with long simple setae along inner margin, with short simple setae along outer margin; propodus with distally denticulate setae along outer margin; dactylus fringed with stout setae around tip; exopod filiform, tapering distally, with long plumose setae on distal portion of mesial margin, without flagellum.

Third maxilliped (Fig. 2G, H) almost flat, smooth, with very sparse granules; basis completely fused, but with vestigial suture on internal surface; merus slightly bent dorsally, as long as ischium along mesial margin; dactylus with distally denticulate, subterminal setae; exopod subsquamate, with longitudinal row of granules along midline, arcuate and rimmed with short plumose setae along lateral margin, internal exopodal ridge short, exceeding beyond ischialmeral border; epipod reduced; podobranch vestigial.

Cheliped (Fig. 1A) moderate; coxal condyles concealed beneath sternites in both sexes; merus weakly compressed, covered with pearly granules except upper surface and distal half of lower surface, outer margin slightly convex outwards; carpus short, convex dorsally, sloping outwards, covered with microscopic granules around inner and outer margins; palm convex dorsally, convex outwards in proximal half of inner margin, with submarginal, ridged row of small granules along inner margin, inner and outer margins rimmed with small granules; fingers tapering distally, 0.7- 0.8 time as long as palm along outer margin; cutting edges blunt and ovally gaping for proximal 0.7, thin and meeting for distal 0.3.

Ambulatory legs (Fig. 1C) similar in shape, gradually decreasing in length from first to fourth, covered with microscopic granules; coxal condyles completely concealed beneath carapace in both sexes; meri, carpi and propodi subcylindrical; dactyli subconical, slightly incurved, with simple acute tips.

Male thoracic sternites as in Figure 1D; episternites not divided entirely, coarsely covered with pearly granules of various sizes; first to fourth sternites fused together; first sternite divided from second by transverse groove; sutures between fourth and fifth sternites to seventh and eighth sternites interrupted medially; abdominal cavity reaching to medial portion of first segment, ridged on margin at first sternite; margin rimmed with pearly granules along first to fourth sternites.

Female thoracic sternites covered with closely-set, flattened, round granules of various sizes; first sternite divided from second by deep groove; second to fourth sternites fused together; abdominal cavity reaching to buccal cavern; margin of abdominal cavity weakly ridged along first sternite.

Male abdomen (Fig. 1E) appears smooth, but actually entirely covered with inconspicuous flat granules, with formula of 1+R+T; first segment short, transversely subrectangular; main fused section composed of second to sixth segments, elongate trapezoidal, weakly swollen at both sides of proximal fourth, sulcate between swells, roundly convex proximally at median part of proximal margin, with pearly granules around proximal margin, with small notch at remnant border between fifth and sixth segments on lateral margin; distal margin of main section triangularly protruded, slightly hooked at tip; telson tongue-shaped, fringed with very short setae.

Female abdomen (Fig. 1F) entirely covered with inconspicuous flat granules, with formula of (1)+2+3+R+T; first segment very short, transversely subrectangular, medially concealed beneath carapace; second and third segments short, transversely subrectangular, medially convex posteroventrally, covered with pearly granules, proximal margins medially convex proximally; main fused section composed of fourth to sixth segments, ovate, moderately convex ventrally, shallowly sulcate along midline, but evenly convex at proximal and distal portions of sulcus, with two transverse sutures between remnant segments, sutures interrupted medially and marginally; telson elongate tongue-shaped, pointed at tip, fringed with short setae.

First male pleopod (Fig. 1G, H) slender, calcareous in proximal 0.7, translucent in distal 0.3, with aperture on proximal 0.2 of mesial margin; distal 0.3 narrowed, with long setae on proximal part; tip curving laterally, broadened, lobular, with small notch on mesial margin. Second male pleopod (Fig. 1I) short, filiform, about 0.3 time as long as first one; tip triangular. Male genital pore with coxal-sternal opening

REMARKS

Nursia jousseaumei was originally and subsequently described by Nobili (1905, 1906) on the basis of 10 males and nine females which are heterocollection from the Red Sea and Perim and one male from Obock. However, only 15 specimens from Red Sea and Perim are extant, and the material from Obock is actually a young female.

The lectotype series of N. jousseaumei and N. jousseaumei var. cornigera are designated to fix the taxonomy of two closely allied species and to stabilize their nomenclature. Comparison of these two species is shown in the Remarks section of Nobiliella cornigera n. comb.