Key to species of Janiralata in Japanese and Korean waters based on males 1 Cephalothorax without acute projection on anterolateral margin................................................ 2 - Cephalothorax with acute projection on anterolateral margin................................................... 3 2 Dorsal habitus with dark brown pigments; antennula article 1 straight dorsally; male pleopod 1 apex curved medially with conical knobs..................................................................... J. koreaensis Jang, 1991 - Dorsal habitus with dark brown pigments; antennula article 1 slightly curved dorsally; male pleopod 1 apex curved medially without conical knobs......................................... J. plana Ohta, Takano, Kojima & Narimatsu, 2023 3 Pleopod 1 with extending projection on quarter of lateral margin................................................ 4 - Pleopod 1 without extending projection on quarter of lateral margin............................................. 5 4 Posterolateral margin of pleotelson truncated......................................... J. chuni (Thielemann, 1910) - Posterolateral margin of pleotelson curved............................................. J. shiinoi Kussakin, 1962 5 Maxillipedal basis and palp article 1 with setae; medial lobe of maxillula with four serrate robust setae J. kwangsooi sp. nov. - Maxillipedal basis and palp article 1 without setae; medial lobe of maxillula with less than four serrate robust setae....... 6 6 Posterolateral margin of pleotelson truncated; exopod of pleopod 3 with broom setae... J. truncata Kim, Kim & Yoon, 2022 - Posterolateral margin of pleotelson curved; exopod of pleopod 3 without broom setae.... J. sagamiensis Shimomura, 2006 Remarks. The new species is placed in the genus Janiralata based on the following characters defined by Wilson & Wägele (1994): presence of anterolateral projections on cephalothorax, coxae of all pereonites visible in dorsal view, coxae of pereopods II and III bilobed, proximoventral border of pereopod I propodus serrated, dactylus of pereopods II–VII with three claws, male pleopod I distal tips laterally expanded, with projecting subtriangular lateral lobes. Janilalata kwangsooi sp. nov. is similar to its congeners J. koreaensis, J. sagamiensis, and J. truncata from the Korean peninsula in general appearances such as habitus, pereopods, male pleopod 1, and uropod. Their differences include setal formula of appendages, morphology of genitalia, and body ratio. Specifically, J. kwangsooi sp. nov. differs from J. koreaensis in the acute projection on the anterolateral margin of the cephalothorax (present vs. absent), the number of apical serrate setae on the maxillula medial lobe (4 vs. 3), the broader lateral projection of pleopod 1, and the number of plumose setae on the pleopod III’s endopod (3 vs. 5). The new species is also distinguishable from J. sagamiensis based on the number of apical serrate setae on the maxillula medial lobe (4 vs. 3), the armature of the maxillipedal basis (5 vs. 0), and the palp article 1 (2 vs. 0), the L/W ratio of pereopod IV carpus (2.5 vs. 3.5), and setal formula of the antennula, all pereopods, and uropod. Janilalata kwangsooi sp. nov. can be separated from J. truncate by the number of apical serrate setae on the maxillula medial lobe (4 vs. 3), the setal formula of the maxillipedal basis (5 vs. 0), endite (over 10 vs. 10), and the palp article 1 (2 vs. 0), distolateral margin of pleotelson (curved vs. truncate), and chaetotaxy of the antennula, all pereopods, and uropod. Janiralata kwangsooi sp. nov. resembles J. microphthalma Kussakin, 1972 from coastal zone of the Kurile Islands in general appearances including habitus, mouth parts, and pereopods. Both species can be differentiated based on the L/W ratio of antennular article 2 (1.6 vs. 0.7), the setation of mandibular palp article one (3 vs. 1), the number of maxillipedal coupling hooks (3 vs. 2), the setation of maxillipedal palp article one (2 vs. 0), the L/W ratio of female operculum (0.8 vs. 1.3) and the length of the uropod rami. The difference in the ratio between left and right mandibular palps in Fig. 3A & B is attributed to the angle changes in the specimen manipulation. The description and measurement of J. kwangsooi sp. nov. is made herein based on Fig. 3A. DNA barcoding. The mtCOI sequence from one of the four specimens of J. kwangsooi sp. nov. was successfully amplified and deposited in GenBank (OR678210). The assembled sequence using forward and reverse strands was with a length of 679 bp and a GC content of 35.8%. The mtCOI uncorrected p-distance (Table 1) between J. kwangsooi sp. nov. and J. occidentalis was 24.3%, while the distance between the new species and J. plana ranged from 28.5 to 29.5%. The distance between J. occidentalis and J. plana varied from 28.1% to 28.7%.

Published as part of Kim, Jeongho & Lee, Taekjun, 2024, A new species of Janiralata Menzies, 1951 (Isopoda: Asellota, Janiridae) from Korea, pp. 427-441 in Zootaxa 5458 (3) on pages 438-439, DOI: 10.11646/zootaxa.5458.3.7, http://zenodo.org/record/11547682