Arcturina serrulatus sp. nov. and a new record of Limnoria rhombipunctata (Crustacea: Malacostraca: Isopoda) from South Korea Author Song, Ji-Hun Author Park, Taeseo Author Kim, Won Author Min, Gi-Sik text Zootaxa 2017 4286 3 411 424 journal article 32738 10.11646/zootaxa.4286.3.8 e2b95cee-befa-4185-83ba-6ec3a9be90fb 1175-5326 828631 90B41B38-7AAE-4F3E-818B-ED36A7CFF007 Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 Figs 6–10 Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 : 251 –259, figs 1–3. Material examined. 1 female (NIBRIV0000470351) ( Figs 6 A–C & 7A, B), total length 6.8 mm , Goraebawi (Whale rock, Diving point), Oho-ri , Jugwang-myeon , Goseong-gun , Gangwon-do , South Korea , 38°19'39''N , 128°33'45''E , 10 m , SCUBA diving and rinsing Zostera sp., 28 November 2012 , coll. T. Park & Y. Eun . 1 female (NIBRIV0000470352), total length 4.5 mm , same location and collectors as above. Description. Female. Body ( Figs 6 A–C & 7A, B) oblong, about 3.4 times as long as greatest width; surface covered with thin setae. Head globular, frontal margin slightly concave. Pereonite 1 longest; 2–5 similar length; 7 shortest. Coxae of pereonites 2–7 large, well visible dorsally. Pleonites 1–4 posterior margins with transverse ridges. Pleonite 5 , 0.9 times as long as pleotelson dorsally, with anterior transverse carina and 3 distinctively large nodes, each node surrounded by thin setae. Pleotelson with 1 large median node, followed posteriorly by 2 pairs of carinae, and laterally with 1 more pair of short carinae; posterior margin of pleotelson fringed with stout setae between which are short scale spikes; lateral crests without tubercles. Colour ( Fig. 6 A–C) dark yellow in ethanol. FIGURE 6. Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 , female. A, body, dorsal view; B, pleonites and pleotelson, dorsal view; C, pleotelson, lateral view. Scale bars = 1mm (A), 0.5 mm (B, C). FIGURE 7. Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 , female. A, body, dorsal view; B, body, lateral view; C, antennula; D, antenna. Scale bars = 1 mm (A, B), 0.1 mm (C, D). Antennula ( Fig. 7 C) with 3 flagellar articles; second articles with about 6 aesthetascs. Antenna ( Fig. 7 D) with 4 flagellar articles. Right mandible ( Fig. 8 A) palp with 3 articles; incisor beak-like; lacinia mobilis apically bifurcate. Maxillula ( Fig. 8 B), outer lobe with 7 apical pectinate spines, lateral margin with simple setae; inner lobe with 3 stout pappose setae. Maxilla ( Fig. 8 C) comprises 3 lobes. Maxilliped ( Fig. 8 D) palp with 5 articles, distal article smallest; apex of endite with 5 pappose setae and 1 stout seta, inner margin with 1 coupling hook; epipod narrowed distally, triangular, reaching past palp articulation. Pereopod 1 ( Fig. 9 A) ischium without tubercles and ventral comb seta; merus with 5 tubercles, without ventral comb seta; carpus with 2 tubercles, without ventral comb seta; propodus inferodistal margin with 2 comb setae. Pereopod 2 ( Fig. 9 B) ischium with 1 tubercle; merus and carpus with 2 tubercles, with 1 ventral comb seta, respectively; Pereopod 3 ( Fig. 9 C) ischium with 2 tubercles; merus with 2 tubercles and 1 ventral comb seta; carpus with 2 tubercles, without ventral comb seta. Pereopod 4 ( Fig. 9 D) smallest; ischium with 2 tubercles; merus and carpus with 2 tubercles and 1 ventral comb seta, respectively. Pereopod 5 ( Fig. 9 E) ischium with 1 tubercle; merus and carpus with 2 tubercles and 1 ventral comb seta, respectively. Pereopod 6 ( Fig. 9 F) ischium with 1 tubercle; merus with 2 tubercles and 7 ventral comb setae; carpus with 2 tubercles and 5 ventral comb setae. Pereopod 7 ( Fig. 9 G) longest; merus with 15 ventral comb setae; carpus with 10 ventral comb setae. All pereopods with bifid secondary unguis. Pleopod 1 ( Fig. 10 A) peduncle with 3 coupling hooks on inner margin; both rami with numerous plumose setae. Pleopod 2 ( Fig. 10 B) peduncle with 2 coupling hooks; both rami with plumose setae up to 0.4 times as long as exopod. Pleopods 3 and 4 ( Fig. 10 C, D) peduncle with 2 coupling hooks. Pleopod 5 ( Fig. 10 E) peduncle and both rami without seta. Uropod ( Fig. 10 F) peduncle with 3 distolateral tubercles; endopod 0.6 times as long as peduncle; exopod short, 0.4 times as long as endopod, claw well developed. Molecular data. The CO1 sequences obtained from the materials of L. rhombipunctata were deposited in GenBank (accession numbers: KX236457 and KX236458 ). Habitat and ecology. Limnoria rhombipunctata , a seagrass borer, was collected from a seagrass-covered sea bottom, 10 m in depth. FIGURE 8. Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 , female. A, right mandible; B, maxillula; C, maxilla; D, maxilliped. Scale bars = 0.1 mm (A–D). FIGURE 9. Limnoria rhombipunctata Yoshino, Watabe & Ohsawa, 2017 , female. A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pereopod 6; G, pereopod 7. Scale bars = 0.1 mm (A–G). Substrate. The rhizome of Phyllospadix iwatensis ( type locality, Japan ) and Zostera sp. ( South Korea ), respectively. Distribution. Japan ( Yoshino et al. 2017 ), eastern coast of South Korea (this study). Remarks. To date, Limnoria includes six seagrass-boring species, i.e. L. agrostisa Cookson, 1991 , L. mazzellae Cookson & Lorenti, 2001 , L. raruslima Cookson, 1991 , L. rhombipunctata , L. simulata Menzies, 1957 , and L. zinovae ( Kussakin, 1963 ) . Among them, L. rhombipunctata was described based on male specimens collected from the rhizomes of Phyllospadix iwatensis (seagrass) in Japan . Herein, this species is described based on female specimens collected from the rhizomes of Zostera sp. (seagrass) in South Korea . The morphology of the specimens of L. rhombipunctata collected from South Korea agrees well with the illustrations and description of Yoshino et al. (2017) ; however, we found some sexual dimorphisms in the Korean specimens as follows: (1) maxillipedal epipod with simple setae (vs. maxillipedal epipod without simple setae in the original description); and (2) more numerous setae on pereopods (vs. few setae on pereopods in the illustration of the original description).