A new species of Stylicletodes Lang, 1936 (Copepoda: Harpacticoida: Cletodidae) from the East China Sea, including an updated key to species and synopsis of distribution records Author Ma, Lin 0000-0001-8906-8498 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. malin @ qdio. ac. cn; https: // orcid. org / 0000 - 0001 - 8906 - 8498 & Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China. malin@qdio.ac.cn Author Liu, Qing He 0000-0001-8906-8498 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. malin @ qdio. ac. cn; https: // orcid. org / 0000 - 0001 - 8906 - 8498 & Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China. hdqinghe @ 126. com; https: // orcid. org / 0000 - 0003 - 0832 - 4344 malin@qdio.ac.cn Author Li, Xin Zheng 0000-0001-8906-8498 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. malin @ qdio. ac. cn; https: // orcid. org / 0000 - 0001 - 8906 - 8498 & Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China. & Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China. hdqinghe @ 126. com; https: // orcid. org / 0000 - 0003 - 0832 - 4344 & Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China. lixzh @ qdio. ac. cn; https: // orcid. org / 0000 - 0001 - 6344 - 6542 malin@qdio.ac.cn Author Huys, Rony Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW 7 5 BD, U. K. text Zootaxa 2021 2021-10-12 5051 1 423 442 journal article 4029 10.11646/zootaxa.5051.1.17 5edc796d-8171-47cc-95d3-4a0b8fd89f53 1175-5326 5563831 168B0219-6287-4C93-B37F-0451BDAAB99F Stylicletodes wellsi sp. nov. ( Figs. 1–7 ) urn:lsid:zoobank.org:act: A5629512-EA36-4481-A075-61A97BF2EA94 Type locality. East China Sea ( 29°31.002’N , 122°36.798’E ); 25 m depth ; silt . Type material. Holotype : ♀ dissected on three slides ( MBM189255 ) . Paratypes : (a) 1 ♀ dissected on five slides ( MBM189256 ) , 1 ♂ ( MBM189257 ) on three slides; from type locality; (b) 1 ♂ ( MBM189258 ) partly dissected on two slides; from East China Sea ( 29°25.656’N , 122°58.998’E ); 61 m depth ; fine sand. All type specimens collected on 12 December 2016 . Other material. (a) 1 ♀ ( MBM189259 ); from type locality; collected on 12 December 2016 ; (b) 1 ♀ ( MBM189261 ); 29°25.656’N , 122°58.998’E ; 61 m depth ; fine sand; collected on 12 December 2016 ; (c) 1 ♀ ( MBM189260 ); 28°52.998’N , 122°44.502’E ; 66 m depth ; silt; collected on 18 December 2016 ; (d) 1 ♂ ( MBM189262 ), 31°40.2’N , 122°30’E ; 28 m depth ; silt; collected on September 2016 ; (e) 1 ♂ ( MBM189263 ) DH4- 5; 28°38.4’N , 124°37.8’E ; 81 m depth ; silt; collected on October 2014 . All specimens collected in the East China Sea and preserved in 75 % ethanol. Etymology. The species is named in honour of Professor John Berkeley James Wells, in recognition of his massive contributions to our knowledge of harpacticoid taxonomy and systematics. Description of female. Total body length, measured from anterior margin of rostrum to posterior margin of caudal rami, ranging from 365 to 392 μm (mean = 377 μm; n = 4). Habitus ( Fig. 1A, B ) slender, curved ventrally in lateral aspect; P1-bearing somite fused to cephalosome forming cephalothorax. Without distinct demarcation between prosome and urosome. Rostrum fused to cephalothorax; triangular, ventrally recurved in lateral aspect, with two sensilla subapically. All somites with dorsal setules along posterior margin except for anal somite. Prosomites with pairs of papillary socles dorsally, each bearing one apical sensillum. Genital double-somite with vestigial P6 represented by two setae (outermost seta longer than innermost) in proximal half of genital somite ( Fig. 1C ); ventral surface relatively smooth, posterior margin with transverse row of strong spinules; genital field with large copulatory pore located near posterior margin. Genital double-somite and second abdominal somite with dorsolateral and ventrolateral papillary socles around posterior margin ( Fig. 1A–C ); ventral surface of second and third abdominal somites with transverse spinule row near posterior margin ( Fig. 1C ). Ventral surface of anal somite partially cleft medially ( Fig. 1C ); anal operculum ( Fig. 1A, C ) produced into long setular extension, flanked by two sensilla. Caudal rami ( Fig. 1B ; note that the rami in Fig. 1A are foreshortened because of the mounting position of the specimen) exceedingly narrow and elongated, about 13 times as long as wide; with one outer proximal seta, distally with three setae, inner margin with one seta near distal fifth of caudal ramus. Antennule ( Fig. 2A ) five-segmented; surface of all segments smooth; fourth segment shortest; with aesthetasc on third segment; fifth segment with two spiniform setae along anterior margin, four apical setae, and three setae along posterior margin. Armature formula: 1-[1], 2-[4], 3-[3 + (1 + ae)], 4-[1], 5-[9]. Antenna ( Fig. 2B ). Surface of allobasis smooth; with one proximal and one subdistal abexopodal seta. Exopod one-segmented, with two setae, one subdistal and one distal. Free endopodal segment with longitudinal row of inner spinules proximally; some outer spinules subdistally; two outer subdistal spines laterally; one pinnate outer distal spine; one geniculate apical seta and three apical spines; and one inner distal spine. Labrum ( Fig. 1D ) triangular, with few long spinules around pointed apex. Mandible ( Fig. 2C ). Gnathobase elongate and narrow; with four teeth. Palp vestigial, represented by two slender setae. Maxillule ( Fig. 2D ). Arthrite with five naked distal elements around distal margin; coxal endite with two setae; basis with two apical setae. Maxilla ( Fig. 2E ). Syncoxa unornamented, with two endites, proximal endite with one strong seta; distal endite with one pinnate and two naked setae; allobasis with one strong claw bearing one seta; endopod represented by two slender setae. Maxilliped ( Fig. 2F ) three-segmented, comprising of unarmed coxa and basis, and one-segmented endopod represented by distal claw. FIGURE 1. Stylicletodes wellsi sp. nov. (♀): A, habitus, dorsal (holotype); B, habitus, lateral (paratype); C, urosome with spermatophore attached to genital field, ventral (paratype; P5-bearing somite omitted); D, labrum (paratype). Scale bars: A–B = 50 μm, C = 20 μm, D = 10 μm. FIGURE 2. Stylicletodes wellsi sp. nov. (♀): A, antennule, ventral; B, antenna (missing apical seta indicated by arrow); C, mandible; D, maxillule; E, maxilla; F, maxilliped. A–C, D–G based on holotype; B, E–F based on paratype. Scale bars: 10 μm. P1 ( Fig. 3A–B ) slender. Intercoxal sclerite narrow, straight and naked. Coxa without ornamentation. Basis with two strong spinules around base of robust outer basal spine. Exopod three-segmented, all segments without armature along inner margin; first segment slightly shorter than second, each with one spinulose spine and several spinules along outer margin; distal segment about three times as long as second, with two spinulose apical setae, and two spinulose outer spines. Endopod two-segmented; proximal segment short, unarmed; distal segment about 8.4 times as long as proximal, with row of inner spinules subdistally; with one subdistal inner seta and one unipinnate seta apically. P2 ( Fig. 3C–D ) slender. Intercoxal sclerite unornamented. Coxa almost square, without ornamention. Basis with transverse row of spinules subdistally, with outer spine. Exopod three-segmented, all segments without armature along inner margin; first segment with spinules along distal and outer margins, and one spinulose outer spine; second segment about 1.5 times as long as first, with one spinulose spine and few spinules along outer margin; distal segment about 3.3 times as long as second, with row of spinules along inner margin, two spinulose apical setae and two spinulose outer spines. Endopod two-segmented; proximal segment short, unarmed; distal segment about 16.7 times as long as proximal, with two strong spinules near inner subdistal margin, spinule row along outer margin, and two long, spinulose apical setae. P3 ( Fig. 4A ) with smooth and wide intercoxal sclerite. Coxa smooth, almost trapezoidal. Basis with transverse row of spinules, with long outer seta (not shown in figure). Exopod three-segmented; first segment with outer and subdistal spinules and one spinulose outer spine; second segment as long as first, with one spinulose inner seta, and one spinulose spine and several spinules along outer margin; distal segment about 2.5 times as long as second, with two spinulose inner setae, two spinulose setae and one spinulose spine apically, and one spinulose outer spine. Endopod two-segmented; proximal segment short, unarmed; distal segment about 12.3 times as long as proximal, with two spinules along inner margin, long row of spinules along outer margin, and two naked apical setae. P4 ( Fig. 4B ) slender. Intercoxal sclerite smooth and wide. Coxa smooth, slightly broader than long. Basis with row of subdistal spinules and long, sparsely plumose, outer seta. Exopod three-segmented; first segment with few subdistal spinules and one spinulose outer spine; second segment as long as first, with one spinulose inner seta and one spinulose outer spine; distal segment about 2.8 times as long as second, with one spinulose inner seta, two spinulose setae and one spinulose spine apically, and one spinulose spine and several spinules along outer amrgin. Endopod two-segmented; proximal segment short, unarmed; distal segment about 10.7 times as long as proximal, with several inner spinules long inner and outer margins, and one spinulose apical seta. Armature formulae of P1–P4 as follows:

Exopod	Endopod
P1	0.0.022	0.110
P2	0.0.022	0.020
P3	0.1.222	0.020
P4	0.1.222	0.010

P5 ( Fig. 7C ). Fifth legs not fused medially. Baseoendopod and exopod not fused, elongate, the former with outer basal seta. Endopodal lobe extending to almost halfway length of exopod; with four naked setae (one inner and three apical), median apical one reduced in length. Exopod long, about 12.5 times as long as greatest width; with three outer, one apical, and one subdistal inner seta; all setae naked. Description of male. Total body length, measured from anterior margin of rostrum to posterior margin of caudal rami, ranging from 360 to 380 μm (mean = 369 μm; n = 3). Habitus ( Fig. 5A ) generally as in female, except urosomites 2 and 3 not fused, and pro- and urosomites without setules dorsally; transverse spinular row on first abdominal somite shorter and abdominal spinulation sparser than in female. Antennule ( Fig. 5C ) chirocer, five-segmented with geniculation between fourth and fifth segments; surface of all segments smooth; with aesthetasc on fourth and fifth segments. First segment with one naked seta; second segment with small plumose seta and five naked setae; third segment shortest; fourth segment swollen; apex of fifth segment recurved. Armature formula: 1-[1], 2-[6], 3-[6], 4-[2 + (1 + ae)], 5-[7 + (1 + ae)]. Antenna, mandible, maxillule, maxilla, maxilliped, and P4 as in female. P1 ( Fig. 6A ). Intercoxal sclerite narrow, straight and naked. Praecoxa narrow, triangular, without ornamentation. Distal segment of endopod about seven times as long as proximal, with two spinules along inner margin. Otherwise as in female. P2 ( Fig. 6B ) as in female, except for distal segment of endopod slightly swollen medially, and with more spinules along inner margin. P3 ( Fig. 7A ) Coxa and basis as in female, except for fewer subdistal spinules on basis. Endopod sexually dimorphic, three-segmented; first segment as in female; second segment longest, with spiniform recurved apophysis arising from inner margin; third segment with two naked apical setae. Exopod three-segmented, first and second segments as in female; third segment with three inner setae, otherwise as in female. P5 ( Fig. 7B ). Fifth legs not fused medially. Baseoendopod with outer basal seta and vestigial endopodal lobe bearing two naked setae apically and two spinules subdistally along inner margin. Exopod elongate, about 5.8 times as long as greatest width; with one outer, one subdistal inner and two apical setae. Sixth legs represented by unarmed flaps.