Ng, Lee & Yu, 1994
A very large Chaceon, cw/cl 185/159 mm, dorsal surface convex transversely and longitudinally. Gastric region swollen, strongly rugose and punctate but not granulose. Hepatic regions gently convex, slightly rugose, not granulose. Each branchial region with one distinct, transverse granulated ridge opposite fourth and fifth antero-lateral teeth; with one weaker, less distinct, shorter ridge both anterior to, and posterior to main ridge; postero-branchial region swollen, strongly granulose and rugose. Suborbital, subbranchial and subhepatic regions smooth; pterygostomial region rugose, punctate. Median frontal teeth slightly smaller and extending slightly forward of lateral frontal teeth, distance between median frontal teeth ca. 0.7 times, distance between median and lateral frontal teeth. Supraorbital margin with a small submedian fissure and another adjacent to external edge; fissures not obvious from dorsal view. Infraorbital margin lined with small rounded granules, inner edge with sharp, acutely triangular tooth. Antero-lateral margin convex; first, third, and fifth antero-lateral teeth small, low, triangular, not spiniform, second and fourth very low to almost obsolete. Postero-lateral margin distinctly convex, rugose. Posterior margin of carapace subcristate, median margin distinctly concave. Cornea of eyes well-developed, pigmented. Antennules folding obliquely, basal segment occupying three-quarters of fossa. Antenna short, basal segment rectangular, not dilated, occupying part of orbital hiatus, movable, not fused with carapace.
Third maxilliped merus squarish; external angle rounded, without auriculiform lobe. Ischium subrectangular, with deep oblique median sulcus. Suture between ischium and basis incomplete, interrupted medially. Exopod stout, reaching half length of merus; flagellum well developed, longer than width of merus.
P1 subequal in size, right chela slightly larger, more inflated. Outer surface rugose to granulose. Merus with distinct, sharp subdistal tooth on dorsal margin, ventral margin with very strong distal tooth. Carpus with strong well-developed sharp tooth on distal inner margin, outer surface sternly rugose, with uneven ridges arranged in a semi-reticulate pattern, without spine or sharp granule. Outer surface of palm with distinct, raised, median granulose ridge. Fingers longer than palm, cutting edges of fingers of right (larger) chela with molariform, crushing teeth on proximal one-third of basal and well developed teeth and denticles on distal two-thirds; cutting edges of fingers of left (smaller) chela with well-developed teeth and denticles. P5 dactylus slender, curved; appears dorso-ventrally compressed, dorsal margin flattened, cross-section T-shaped, height at mid length slightly greater than width (width at midlength 0.9-1.0 times height). Propodus laterally compressed, 4.6-6.0 times longer than high. Merus laterally compressed, slender, 5.0-5.4 times longer than high, 0.6-0.7 times cw, dorsal margin with low, rounded subdistal tooth, not sharp, usually more pronounced in first three pairs of legs.
Surface of sternum smooth to slightly granulose; sternites 1 and 2 fused, suture absent, forming triangular structure; sutures between sternites 2 to 6 incomplete, interrupted medially; sutures from sternite 6 onwards complete; abdomen-locking button on posterior edge of sternite 5. Male abdomen triangular, length 1.6 times width; sutures of segments 3-5 deep, distinct, but segments not movable; segment 7 broadly triangular. Male Pl 1 short, very stout, C-shaped; proximal part sub-truncate, outer margin almost straight; distal part tubular, gradually tapering to tip, gently curving outwards, tuft of long setae present on submedian part of outer margin, distalmost areas covered with numerous, very small granules. Male Pl 2 almost as long as male Pl 1, with distinct distal segment about one-quarter total length of male Pl 2. (Ng et al., 1994: 372)
Type locality: Tungsha Islands, South China Sea, 438-636 m.
Range: Japan - Hyuga-nada (Ng & Manning, 1998); Taiwan - Tung-kang; South China Sea - Tungsha Islands (Ng et al., 1994, Ng et al., 1998a, Ng & Manning, 1998).