Cleantioides Longicornis, a New Species of Holognathidae (Crustacea, Isopoda, Valvifera) in the Yangtze Estuary, China

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Cleantioides longicornis, a new species of Holognathidae (Crustacea, Isopoda, Valvifera) in the Yangtze Estuary, China

Wenliang Liu 1,3, Poore Gary C. B. 2, Jianjian Lu 1

1State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China

2Museum Victoria, GPO Box 666, Melbourne, Vic. 3000, Australia

3Institute of Oceanology, CAS, the Marine Biological Science Museum, Qingdao 266071, China

Abstract Cleantioides longicornis, a new species, is described on the basis of specimens collected from Yangtze estuary, Shanghai, China. The new species can be distinguished from the closely related species, C. albaniensis Poore & Lew Ton, by the narrower antenna 2; a slightly notched pleotelson; arrangements of spines or pectinate spines on preopods.

Key words: Isopoda, Holognathidae, Cleantioides, taxonomy, China

Introduction The valviferan isopod family Holognathidae is characterised by a semicylindrical body of even width throughout, parallel-sided pleotelson more or less apically rounded, and a short pereopod 4 bearing numerous robust setae. Plesiomorphic features: four pleonites separated laterally, the greatest number of any valviferan; penes separate from the base; two uropodal rami (in two of the four genera); and a 5-articled five maxillipedal palp with articles 2 and 3 not articulating (Poore & Lew Ton, 1990). Cleantioides Kensley & Kaufman, 1978 is diagnosed by: the absence of the uropodal exopod (one ramus only); and antennae 1 and 2 flagella clavate, a minute article much smaller than peduncle article 3 in antenna 1 – features that distinguish it from Cleantis Dana, 1849 in particular (Poore & Lew Ton, 1990). Twelve species are known, from the eastern and northern Pacific, Caribbean and central eastern Atlantic, and South Africa (Table 1). Table 1. Species of Cleantioides with relevant literature C. albaniensis Poore & Lew Ton, 1990 - southern Australia. C. bruscai (Kensley, 1987) - Belize (Kensley & Schotte, 1989). C. emarginata Kwon & Kim, 1992 - Korea. C. japonica (Richardson, 1912) - Japan; Korea (Kwon, 1986; Nierstrasz, 1941). C. natalensis (Barnard, 1925) - South Africa (Barnard, 1936, 1955; Kensley & Kaufman, 1978). C. occidentalis (Richardson, 1899) - western North America (Richardson, 1905 (Brusca & Iverson, 1985; Brusca & Wallerstein, 1979a, 1979b; Kensley, 1978; Richardson, 1905; Schultz, 1969). C. planicauda (Benedict, 1899) – Florida (type locality); Sea of Japan; southern Mexico to Georgia; Caribbean; south-eastern Brazil (Richardson, 1905 (Brusca & Iverson, 1985; Brusca & Wallerstein, 1979b; Clark & Robertson, 1982; Richardson, 1905; Schultz, 1969). C. poorei Kwon & Kim, 1992 - Korea. C. rotundata (Kussakin, 1982) - western North Pacific; Japan. C. striata Poore & Lew Ton, 1990 - eastern Australia.

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C. verecundus Kensley & Clark, 1998 - Florida, USA. C. vonprahli Ramos & Rios, 1988 - Columbia. In this paper we describe and illustrute a new species from the Yangtze River, southern China. The new species was discovered in the course of a survey of the Yangtze River. The relationship between the new species and the closely related species, Cleantioides albaniensis is discussed. The known species of Cleantioides differ scarcely at all in details of mouthparts and pleopods. Poore & Lew Ton (1990) described and illustrated two Australian species in detail. For the new species, these features are figured but not described in many words.

Material and methods Specimens were collected by Agassiz trawl and then preserved in 75% alcohol. The drawings were made with the aid of drawing tube mounted on a Zezss Stemi Sv11 compound microscope. The following abbreviations are used throughout the text: TL, total length of body; SR@CWRC, the Specimen Room of Chongxi Wetland Research Center; NMV, Museum of Victoria. Type specimens are deposited in the collections of the Chongxi Wetland Research Center Specimen Room in Shanghai.

Systematics

Suborder Valvifera Sars, 1882

Family Holognathidae Thomson, 1904

Genus Cleantioides Kensley & Kaufman, 1978

Cleantioides longicornis sp. nov.

Material examined Holotype, Ar-Cr-027 (SR@CWRC), 1 female (TL, 21.6 mm), Yangtze estuary (121°58.57É, 31°23.11Ń), 5 m depth, bottom soft mud, 7 April 2006, coll. Zhang Feijun and Liu Wenliang. Paratypes: Ar-Cr-027 (SR@CWRC), 2 males, (TL, 14.9, 15.1 mm), estuary of Yangtze River (122°1.58'E, 31°42.38Ń), 7 m depth, bottom sand, 30 September 2006, coll. Zhang Heng and Liu Wenliang；Ar-Cr-027 (Museum Victoria)，1 female, (TL, 16 mm), Ar-Cr-027 (Museum Victoria)，1 male, (TL, 14 mm), estuary of Yangtze River (122°26.67É, 31°49.58Ń), 6 m depth, bottom soft mud, 29 September 2006, coll. Zhang Heng and Liu Wenliang.

Diagnosis Head with a deep longitudinal groove running from the anterior margin, with a transverse groove posteriorly; eyes present. Pereonite 1 little longer than pereonite 2. Antenna 2 long and narrow, about 5 times as long as antenna 1.Merus of pereopods 1and 2 with 1 spine and some pectinate spines on anterodistal angle. Dactylus of pereopod 4 reduced to unguis alone, with mesiodistal spines on ischium, merus and carpus.Pereopod 5 dactylus hooked. Pereopod 7 with rows of pectinate spines on posterior margin of merus and propodus.

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Description Adult female. Body almost 5 times as long as wide, with even brown pigment dorsally and on uropods. Dorsal surface largely smooth, without setae. Head 1.6 times as wide as long, anterior margin sinuous, excavate at midpoint; posterior margin convex; dorsally with a longitudinal groove in middle of anterior margin and transverse groove at back of head. Pereonite 1 longer than rest, pereonites 5-7 progressively shorter. Pleotelson 0.4 whole length; pleonite 1 free and articulating, pleonites 2 and 3 well defined but not articulating, pleonite 4 incised laterally; pleotelson parallel-sided and with semicircular apex, dorsum of distal half with well-defined oblique oval plane. Antenna 1 reaching to middle of second article of antenna 2 peduncle; peduncle article 2~2.2 times as long as wide; flagellum subequal to 0.5 length of last article of peduncle, with 6 short apical aesthetascs. Antenna 2 about 0.3 length of body, long and narrow, 8 times as long as wide; flagellum of 1 article, with fine setae outer margin and a dense clump at apex. Mandibles asymmetrical; molar process bearing anterior spines, fine setae and a ridged triturating surface; spine row of 5 dentate spines; lacinia moblis a toothed blade (left) or a 3-spined tooth (right); incisor 4-toothed, broader and squarer on left. Maxilla I inner plate with 4 complex setae; outer plate with 11 apical spines, some toothed. Maxilla 2 inner plate with oblique row of 11 plumose setae on inner margin plus about 8 simple apical setae; middle and lateral plates with oblique rows of 8 setae. Maxillipedal endite with row of 3 plumose setae mesially; some setae laterally at base of palp; palp twice long as endite; articles 2-5 medially setose, 3 and 4 with fine lateral setae; article 3 mediodistally lobed; article 5 wider than long, 0.2 length of article 4; epipod apically truncate. Pereopods 1-3 increasing in length; pereopod 4 0.4 length of pereopod 3; pereopods 4-7 increasing in length. Pereopod 1 with 1 posterodital spine on ischium; 1 long spine and 3 pectinate spines (2 long，1 short) on anterodistal angle of merus; some posterior spines on merus, carpus and propodus; propodus with 2 setae on anterodistal angle. Pereopods 2 and 3 similar. Pereopods 2 with 1 anterodital spine on ischium; merus with 1 spine and 5 pectinate spines on anterodistal angle, 3 spines on middle posterior margin; 2 rows of spines on posterior margin of carpus; propodus with 2 setae on anterodistal angle, 6 rows of spines on posterior margin. Pereopod 4 ischium with 4 mesiodistal spines; merus, carpus and propodus with posterodistal U-shaped rows of 8, 18 and 12 spines respectively; merus with 3~4 mesiodistal pectinate spines and 1 anterodistal pectinate spine; carpus with 4 mesiodistal pectinate spines, propodus with 1 anterodistal spine; dactylus reduced to a compact unguis only. Pereopod 5 longer than 4, ischiun with 1 anterodistal spine, some fine setae on anterior margin; merus with 1 anterodistal spine, 3 spines on posterior margin; carpus and propodus with 3 spines on posterior margins and setea on anterior margins; dactylus hooked. Pereopods 6 and 7 similar, more elongate than 5. Pereopod 7 ischium with 4 pectinate spines on anteriodistal angle and 2 pectinate spines on mesial face; with 5 and 6 rows of pectinate spines on mesial face and posterior margin of merus and propodus respectively; propodus with 2 anteriodistal pectinate spines

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Oostegites on pereopods 1-5, first much smaller than rest. Pleopod 1 endopod with about 45 plumose setae around all of margin, distal ones little shorter than ramus; exopod with about 80 plumose setae laterally and distomesially. Pleopod 2 with similar arrangement of setae; peduncle with short proximally directed lateral lobe. Pleopod 3 peduncle with mesial setae carried on a digitate lobe; endopod with distal seta; exopod with 30 distolateral plumose setae. Pleopods 4 and 5 rami with short marginal setae laterally. Uropodal endopod with inner angle square, distolaterally rounded, apically truncate; exopod absent.

FIGURE 1. Cleantioides longicornis sp. nov., female holotype: a. habitus in dorsal views; b. antenna 1 (dorsal); c. antenna 2 (dorsal); d. mouth (ventral); e. penis (ventral); f. uropodal ramus (mesial)

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FIGURE 2. Cleantioides longicornis sp. nov., female holotype: g. mandible (mesial); h. MX1 (mesial); i. MX2 (mesial); j. maxilliped (posterior)

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FIGURE 3. Cleantioides longicornis sp. nov., k. pereopod 1 and inner face of merus; l. pereopod 2 and inner face of merus; m, n, o. pereopods 4, 5, 7; p, q, r, s, t. pleopods 1, 2, 3, 4, 5.

Juvenile male. Differs from female in: antenna 2，flagellum of 1 article, with fine setae all over, but thin. pereopods 1-3 and 5-7 with less of fine setae dorsally on ischium, merus, carpus and propodus; without an appendix masculina because of not fully adult; penes attached at the anterior margin of pleonite 1 and separated by a sharp sternal ridge.

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Remarks Cleantioides longicornis is similar to the southern Australia C. albaniensis Poore & Lew Ton, 1990. But the new species differs from the latter in: 1. the antenna 2 is long and narrower (8 times as long as wide, versus 4 times); 2. the distal end of pleotelson is slightly notched (versus with a truncate pleotelson); 3. propodus of pereopod 1 without pectinate spine on mesial face (versus with 10 pectinate spines); 4. pereopod 2 with 2 rows of spines on posterior margin of carpus and propodus with 6 rows of spines on posterior margin (versus with 3 posterior spines on carpus, 2 on propodus); 5. pereopod 4 merus with 3~4 mesiodistal pectinate spines, carpus with 4 mesiodistal pectinate spines (versus without mesiodistal pectinate spines).

Etymology The species name is based on the shape of the antenna 2.

Distribution Presently only known from the type locality.

Acknowledgement The work was supported by the National Basic Research Program of China (2002CB412406) and the Pilot Program of Shanghai Technology and Science Committee (04DZ12049).

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