Comprehensive Description

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General Description

The body is relatively robust, and has an integument that is thin and soft, but not membranous. The surface is smooth. The rostrum is directed forward or slightly downward, and is straight, reaching the distal margin of the first segment of the antennular peduncle to the midlength of second the segment (0.28–0.43 times as long as the carapace in females, 0.39–0.45 times in males). The dorsal margin is sharply carinate, and is armed with 12–17 moderately small teeth,

including 7–10 teeth on the rostrum proper and 4–7 teeth on the carapace posterior to the level of the orbital margin. The posterior-most tooth arises at 0.19–0.24 of the carapace length. The ventral margin is slightly convex to weakly carinate, and is unarmed or armed with 1 minute subterminal tooth. The ventrolateral carina is sharp and merges into the orbital margin. The carapace is about 1.40 times longer than it is wide. The postrostral median ridge is moderately high to high (higher in females than in males), and becomes blunt posterior to the posteriormost tooth of the dorsal rostral series. The ridge extends beyond the midlength of the carapace, and slopes anteriorly to the rostrum, with the dorsal angle up to 155°. The antennal tooth is moderately large, whilst the pterygostomial tooth is strong, reaching well beyond the antennal tooth. The anterolateral margin between the antennal and pterygostomial teeth is concave. The post-antennal groove is shallow, and diverges to the horizontal plane of carapace.The branchial region is moderately convex.

The eighth thoracic sternite has a long median spur directed anteroventrally.

The abdomen is rounded dorsally. The pleura of the anterior three somites are broadly rounded. The fourth pleuron is rounded posteroventrally or has a subacute to blunt point. The fifth pleuron has a strong posteroventral tooth and 1–3 additional denticles on the posterolateral margin. The sixth abdominal somite is 1.25–1.40 times longer than it is high. The telson does not reach the posterior margin of the uropodal endopod, and has a length about 2.50 times the anterior width and about 4.50 times the posterior width. The telson is armed with 6–8 dorsolateral spines that are arranged in a slightly convex row on either side. The posterior margin is gently convex, and is armed with 2 pairs of spines at lateral angles (the mesial spine is about twice length of the lateral spine) and 12–14 plumose setae that are all longer than the mesial pair of lateral spines.

The eyes are fused mesially, each with a small tubercle on the anterodorsal surface. The corneal part is imperfectly developed, ovate in outline, and is unfaceted though diffusely pigmented.

The antennular peduncle reaches or slightly overreaches the distal margin of the antennal scale. The first segment has a conspicuous proximal tubercle on the dorsal surface laterally and a strong distolateral tooth. The dorsal surface has a distinct obliquely longitudinal groove. The stylocerite is sharp, and reaches to the mid-length of the second segment. The distomesial margin has a minute, but sharp tooth. The second segment is stout, and is 1.30–1.40 times as long as it is wide, with a small distomesial tooth. The lateral flagellum is longer than the carapace, whilst the mesial flagellum is somewhat longer than the lateral flagellum.

The antenna has a stout basicerite that bears moderately strong ventrolateral and weak ventral teeth. The carpocerite is stout, but does not reach the midlength of the antennal scale. The antennal scale is 0.38–0.42 times as long as the carapace in females, 0.39–0.50 times in males, and measures 1.75–1.80 times longer than wide. The lateral margin is nearly straight. There is a middorsal ridge on the dorsal surface that slightly diverges against the lateral margin. The distolateral tooth is moderately broad, but falls short of the broadly rounded distal margin of the lamella.

The mouthparts are typical of the genus. The mandible has a molar process that terminates in a blunt tip. The endopod of the maxillule bears a long, setulose, apical setae on the inner lobe. The maxilla has a relatively broad scaphognathite. The exopod of the first maxilliped is broad, with a weak mesial projection that probably represents a reduced flagellum. The second maxilliped is relatively stout. The epipod has a bilobed podobranch. The third maxilliped overreaches the antennal scale by about 0.50 times the length of the ultimate segment. The ultimate and penultimate segments combined are arcuate. The ultimate segment is trigonal in cross section, and has a subtruncate terminal margin with 2 or 3 spines. The antepenultimate segment is somewhat flattened dorsoventrally, and is sinuously curved in a dorsal view, bearing 1 slender spine at the ventrolateral distal angle. The dorsal surface of the antepenultimate segment has a prominent tuft of short to long setae proximomesially, whilst the mesial surface has several vertical rows of short stiff setae distal to midlength. The coxa is stout, and has a small projection dorsal to the base of epipod. The epipod is small, slightly bilobed, and is directed distolaterally.

The first pereopod is sexually dimorphic, being larger in females than in males. The fingers are curved downward and inward. The outer surface of both fingers is convex, whilst the inner surface is concave, and the cutting edges are uniformly offset, closing without gap. Each cutting edge is armed with a fine row of closely set teeth, and the tip of each finger is slightly spooned. The dactylus is 1.4–1.7 times longer than the palm in females, and about 2.0 times in males, with a submarginal row of short, curved setae on the inner surface adjacent to the cutting edge. The palm is much shorter than the fingers, and has a tuft of short setae at the middle of the ventral surface. There is a short, distinct groove on the ventral surface proximally. The carpus is cupped distally to receive the palm, and has an acute or subacute ventrodistal tooth. The dorsodistal mesial margin is rounded. The ventromesial surface has a patch of dense setae and 1 small spine just proximal to the setal patch. The mesial face is shallowly depressed. The merus and ischium are strongly obliquely articulated in a lateral view. The merus is slightly inflated ventrally, and the ischium is always unarmed.

The second pereopod is shorter and more slender than the first pereopod, and does not reach the distal margin of the antennal scale. The fingers are subequal to the palm in length, each terminating in small corneous unguis that cross each other when closed. The cutting edges are a without gap, and each is pectinated with a single row of minute corneous teeth. Thecarpus is slightly longer than the chela. The merus and ischium are obliquely articulated in a lateral view. The ischium is unarmed or armed with 1 spine ventrolaterally.

The third to fifth pereopods are moderately slender, and are generally similar in structure and length although the propodus becomes progressively longer, and the merus progressively shorter from the third to fifth. The third pereopod reaches beyond the distal margin of the antennal scale by 0.30–0.40 times the length of the propodus. The dactyli are small (0.15–0.18 of the propodal length in the third; 0.09–0.18 in the fourth; 0.10–0.15 in the fifth), and are 1.90–2.00 times longer than high, each armed with 3–6 accessory spinules that are arranged in a single row on the flexor margin. The propodi of the third and fourth pereopods have slender spinules arranged in two rows on the ventral surface. The propodus of the fifth pereopod has numerous spiniform setulose setae that are arranged in three or four rows on the distal half of the ventral surface. The carpi are shorter than the propodi. The meri are armed usually with 1 spine ventrolaterally or are rarely unarmed in the third pereopod, armed with 1 spine or unarmed in the fourth, and always unarmed in the fifth. The ischia are always unarmed.

The male first pleopod has an elongate distomesial lobe that bears 4 spiniform setae that are directed mesially or distomesially on the mesial margin. The lateral margin is gently convex, with 6 spiniform setae in the distal half and 5 or 6 setulose setae in the proximal half. The mesial margin is faintly sinuous and has several setulose setae in the proximal half. The appendix masculina is moderately robust, and is almost as long as the appendix interna. It has about 5 spiniform setae terminally or subterminally. The appendices internae on the second to fourth pleopods are small, slender, and taper distally, and are without a terminal cluster of cincinnuli. On fifth pleopod the appendix internae is better developed than others and has a terminal cluster of cincinnuli.

The protopod of the uropod has an acute posterolateral angle. The endopod is subequal in length to the exopod. The exopod has a tiny posterolateral tooth and 1 movable spine just mesial to the posterolateral tooth.

(Komai & Chan, 2010)


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