Nobiliella cornigera ( 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 : 419-421

Nobiliella cornigera ( Nobili, 1905) n. comb.

(Figs 3; 4E, F)

Nursia jousseaumei var. cornigera Nobili, 1905: 398 (type locality: Red Sea); 1906: 152.

TYPE MATERIAL. — Designated here as lectotype series ; Red Sea , coll. Dr Jousseaume, 1891 ; lectotype, 4.3 × 5.2 ( MNHN B 17010) ; paralectotypes, 2 ovig.

4.1 × 4.9, 4.4 × 5.8 (broken at frontal region in larger one) ( MNHN B 28618).

DISTRIBUTION. — Red Sea.

REDESCRIPTION

Carapace (Fig. 3A) subrhomboidal in general outline, 1.2-1.3 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 beaded line except frontal region; upper surface seemingly smooth, but entirely covered with microscopic flat granules. Front moderately produced, medially concave; margin divided into two lobes. Orbit bears only one fissure on dorsal roof, without mesial fissure. Mesogastric region weakly convex longitudinally, shallowly grooved medially. Gastro-cardiac region prominently raised, with pair of gastric low tubercles and cardiac tubercle; gastric tubercles marked with pearly granules; cardiac tubercle prominent, marked with pearly granules. Intestinal region strongly prominent dorsally, with median row of pearly granules, pointed and marked with pearly granules around apex. Hepatic region weakly demarcated; margin concave inwards, separated from epibranchial margin by small V-shaped notch; hepatic facet developed, medially concave behind orbit. Pterygostomian margin projecting antero-ventrally, angled at posterior end. Epibranchial region sloping anteriorly from epibranchial ridge; margin thin, weakly upturned, rounded, strongly convex antero-laterally; epibranchial ridge conspicuous, obliquely extending from near gastric tubercle 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 large triangular tooth at anterior end. Posterior margin weakly trilobate, forming obtuse angle with metabranchial margin; median lobe small; lateral lobes large, triangular.

Ocular peduncle (Fig. 3B) short; antero-dorsal extension onto cornea rectangular, with rounded tip. Antennule 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. Afferent channel with weak oblique ridge, with short setae along ridge; lateral margin with V-shaped notch near anterior end.

Mandible (Fig. 3C, D) well calcified; cutting edge triangular in outline, pointed medially, finely dentate on anterior 0.2; endopod palp missing. Maxillule (Fig. 3E): coxal endite subcylindrical, directed mesially, with some terminal setae; basial endite triangular, with stout setae and thin setae

FIG. 3. — Nobiliella cornigera ( Nobili, 1905) n. comb., lectotype, 4.3 × 5.2 mm ( MNHN B 17010) from Red Sea ; A, carapace, dorsal view; B, frontal region, frontal view; C, mandible, external view; D, same, internal view; E, maxillule, external view; F, maxilla, external view; G, first maxilliped, external view; H, second maxilliped, external view; I, third maxilliped, external view; J, same, internal view; K, cheliped, dorsal view; L, left ambulatory leg, dorsal view; M, female abdomen, ventral view. Scale bars: A, K-M, 1 mm; B-J, 0.5 mm.

on mesial margin; endopod reduced. Maxilla (Fig. 3F): coxal endite small, rounded; basial endite rounded, with some terminal setae; endopod triangular, directed laterally; exopod (scaphognathite) longitudinally expanded into ovate structure, entirely fringed with short plumose setae. First maxilliped (Fig. 3G): 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; exopod reduced, about half as long as endopod, longitudinally filiform, with long subterminal, plumose setae, without flagellum. Second maxilliped (Fig. 3H): endopod with long plumose setae along inner margins of ischium and merus, with short submarginal setae along lateral margin of merus of internal surface, with denticulate setae along outer margin of propodus, 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. 3I, J) almost flat, covered with granules of various sizes, rimmed with small round granules along mesial margins of ischium, merus and exopod; basis completely fused, but with vestigial suture on internal surface; ischium longitudinally convex in lateral 0.7, with longitudinal row of pearly granules on convexity; merus slightly bent dorsally, 1.3 times longer than ischium along mesial margin, convex medially, with row of sparse pearly granules along midline; dactylus with distally denticulate, subterminal setae; exopod subsquamate, with longitudinal row of sparse pearly granules along midline, arcuate and rimmed with short plumose setae along lateral margin; internal exopodal ridge short, exceeding beyond ischial-meral border; epipod reduced; podobranch vestigial.

Cheliped (Fig. 3K) moderate, as long as carapace in female; coxal condyle concealed beneath sternite in female; merus subcylindrical, covered with pearly granules except upper surface, slightly arcuate on outer margin, subflat on upper surface; carpus short, convex dorsally, sloping outwards, covered with microscopic granules around outer margin; palm convex dorsally, convex outwards on inner margin, rimmed with small granules along inner and outer margins; fingers tapering distally, as long as palm along outer margin; cutting edges blunt and leaving oval gape for proximal 0.7, thin, finely dentate and meeting along distal 0.3.

Ambulatory legs (Fig. 3L) similar in shape, gradually decreasing in length from first to fourth, covered with microscopic granules; coxal condyles completely concealed beneath carapace in female; meri and carpi subcylindrical; propodi weakly compressed; dactyli subconical, slightly incurved, with simply acute tips.

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

Female abdomen (Fig. 3M) entirely covered with round flat granules except on grooves, 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, covered with pearly granules, proximal margins weakly convex medially; main fused section composed of fourth to sixth segments, ovate, moderately convex, divided into subregions by two longitudinal and three transverse shallow grooves, its margins rimmed with small round granules; telson elongate tongue-shaped, pointed at tip, fringed with short setae.

REMARKS

Nursia jousseaumei var. cornigera can easily be distinguished from N. jousseaumei s.s. by the following features: 1) the frontal margin divided into two lobes, whereas that of N. jousseaumei s.s. is subtruncate with small median tooth; 2) the triangular tooth of metabranchial margin is larger than that of N. jousseaumei s.s.; 3) the lateral lobe of posterior margin is distinctly triangular, whereas that of N. jousseaumei s.s. is small; and 4) the female abdomen is covered with round flat granules, whereas that of N. jousseaumei s.s. is covered with inconspicuous flat granules. We thus believe that it should be recognized as a distinct species.