The genus Arcoscalpellum Hoek, 1907 belongs tosubfamily Arcoscalpellinae Zevina, 1978(OrderScalpelliformes, Family Scalpellidae Pilsbry, 1907).Diagnostic characteristics of the genus include:capitulum with 14 fully or partially calcifi ed plates;carina with apical or sub-apical umbo; inframedianlatus umbo apical; carinal latus umbo in the middleregion of the carinal margin; caudal appendage uniormulti-articulate. Forty-fi ve Arcoscalpellum speciesare currently recorded. Five species of this genushave been found in the China Sea (Jones et al., 2000;Liu and Ren, 2007).

A. michelottianum (Seguenza, 1876), A. sociabile (Ann and ale, 1905) and A. truncatum (Hoek, 1883)have been reported from Taiwan Isl and (Chan et al., 2009). A. reni Young, 2007 (synonymized name: A.ciliatum Ren, 1983), A. michelottianum (Seguenza, 1876), A. pertosum Foster, 1978 and A. sociabile (Annandale, 1905) have been recorded in the EastChina Sea and the South China Sea (Jones et al., 2000; Liu and Ren, 2007). Here, a new species foundin the deep waters of the South China Sea, A. liui sp.nov., is reported.2 MATERIAL AND METHOD

Specimens were collected during an expedition bythe Institute of Oceanology, Chinese Academy ofSciences(IOCAS)in the deep waters of the SouthChina Sea in September 2011. Specimens wereexamined, dissected, and drawn using a dissectingmicroscope. All measurements are in millimeters.Specimens are deposited at IOCAS, Qingdao, China.3 SYSTEMATICS

Infraclass Cirripedia Burmeister, 1834 Superorder Thoracica Darwin, 1854 Order Scalpelliformes Buckeridge & Newman, 2006 Family Scalpellidae Pilsbry, 1907 Subfamily Arcoscalpellinae Zevina, 1978 Genus Arcoscalpellum Hoek, 1907 Arcoscalpellum liui sp. nov.(Fig. 1) 5 ACKNOWLEDGEMENT

We are indebted to Prof. J. Y. LIU(Institute ofOceanology, Chinese Academy of Sciences)for hissupport of the work.

Fig. 1 Arcoscalpellum liui sp. nov. a. side view of body; b. rostrum and surrounding plate; c. dorsal view of carinal latus; d. soft body; e. labrum; f. palp; g. m and ible; h. maxilla I; i. maxilla II;j. caudal appendage and basal part of cirrus VI; k. caudal appendage; l. intermediate segment of inner ramus of cirri VI.

Figure options

Specimens examined: Holotype, K120110-6.Capitulum: length 5.5 mm, width 2.9 mm. Peduncle:length 1.3 mm, width 1.0 mm. Attached to spongespicules. Collected using agassiz trawl in the SouthChina Sea. Station MBMCAS007(17°15.0209′N, 111°20.1947′E)between Hainan and Xisha Isl and s.13 September 2011. Depth 1 238 m. Xu Kui-Dong, Zhang Jun-Long and Ning Ping Coll.

Description: female, capitulum shuttle-shaped, white, with l4 calcifi ed plates. Scutum rectangular, apex produced at tergo-occludent angle; umbo apical, rostral margin slightly arched, upper part of tergalmargin slightly concave, carinal and basal marginsstraight. Tergum triangular, sides straight, umboapical. Carina arched, umbo apical, dorsal surfacefl at. Upper latus rectangular, scutal margin long, carinal and basal margins straight. Rostral latusrectangular, scutal margin longer than the basalmargin. Carinal latus pentagonal, umbo sub-medianof carinal margin, slightly produced. Two carinal latusintersected by few teeth-shape at dorsal part, locatedbelow base of carina. Inframedian latus narrow and long, triangular, umbo apical, extending to the upperlatus. Rostrum small and narrow, umbo apical.Peduncle short, with 11 transversal scales.

Labrum bullae, crest with a row of small teeth.M and ible with three teeth, inferior angle pectinate.Cutting edge of maxilla I notched, with two large and two small spines above, and two large spines and onesmall spine below. Maxilla II with frontal notch, withsetae, maxillar lobe slender and long. Palp small and conical with setae.

Cirral formulae of the anterior and posterior cirri ofthe holotype are as follows:

Anterior rami of Cirri I–VI shorter than posterior, slender and long, each intermediate segment with fourpairs of setae on the anterior margin. Caudal appendageone segment, terminal end with eight setae and oneseta below. Penis absent. Dwarf male not known.

Etymology: the species name is chosen to honorProf J. Y. Liu(Institute of Oceanology, ChineseAcademy of Sciences).

Habitat: deep water of tropical seas, depth1 238 m, attached to sponge spicules.

Distribution: tropical deep seas(South China Sea).4 REMARKS

The new species A. liui sp. nov. is similar to A.gryllum Zevina, 1981, but may be distinguished by anabsence of both fi ne hairs and striae on the capitulum.In addition, each intermediate segment of cirri II–VIhas four pairs of setae on the anterior margin, ratherthan three pairs. The caudal appendage of A. gryllum Zevina, 1981 is curved and naked, while the caudalappendage of A. liui sp. nov. is one lobe-form segment, its terminal end with eight setae and one seta below.A. compsitum (Zevina, 1975) and A. radiatum Rao & Newman, 1972 are similar in the outer surface to A.liui sp. nov., but differ by two carinal latus intersectedby one teeth-shape at dorsal part.