Janiralata kwangsooi, Kim & Lee, 2024

Kim, Jeongho & Lee, Taekjun, 2024, A new species of Janiralata Menzies, 1951 (Isopoda: Asellota, Janiridae) from Korea, Zootaxa 5458 (3), pp. 427-441 : 430-438

Janiralata kwangsooi sp. nov.

urn:lsid:zoobank.org:act:C97BC4EA-4FCC-40F2-87A8-FBBC0DCB78B4

Figs 2‒7 , Table 1

Materials examined. Holotype: 1 male NIBRIV0000911351, Dongyeo islet, Dokdori 53, Ulleung-eup, Ulleunggun, Gyeongsangbuk-do, Korea, 37°243872N 131°861251E, 23m depth, 17℃, 20 June 2023, collected by Taekjun Lee.

Paratypes: 1 male NIBRIV0000911352, 1 male NIBRIV0000911353, 1 male NIBRIV0000911354, 1 male NIBRIV0000911355, 1 female NIBRIV0000911356, same data as holotype .

Diagnosis (male): Antennular article 1 with two broom and two UB setae; mandibular palp article 1 with three simple setae; maxillula medial lobe with four serrate apical setae; maxillipedal basis with five simple setae, palp article 1 with two simple setae; pereopod I ischium with eight UB and 12 simple setae; pleopod 1 with ten simple setae on distodorsal margin; exopod article 2 of pleopod 3 with nine simple setae distally; uropodal protopod with 21 UB setae.

Description (male): Body ( Fig. 2A ) total length measured in holotype 4.2 mm, length 2.2 times longer than wide, preserved specimens white in color.

Cephalothrax ( Fig. 2A ) 0.5 times longer than wide and 0.3 times of whole body (1.3 mm), without rostrum; anterolateral margin concave, with anterior projections; lateral UB setae present, dorsal margin covered with numerous setae; eyes globular, vertical length of 0.3 mm, ommatidia on eyelobe dorsally.

Pereon ( Fig. 2A ) 0.5 times of whole body (2.1 mm), maximal body width in pereonite 6 1.5 times of width of cephalothorax (2.0 mm); dorsal margin and lateral protrusion of each pereonite armed with simple setae.

Pleonite ( Fig. 2A ) 0.1 times longer than wide, no setae present. Pleotelson ( Fig. 2A ) ovoid; 0.8 times longer than wide, 0.3 times of whole body (1.2 mm), posteromedial apex convex, bluntly rounded; posterolateral margin curved, anal opening subterminal, dorsal and lateral margin covered with numerous simple setae.

Antennula ( Fig. 2B ) peduncular article 1 0.9 times longer than wide, with two broom and two UB setae; article 2 1.6 times longer than wide, with three broom, seven UB, and three simple setae; peduncular article 3 1.5 times longer than wide, with one UB and two simple setae on distal corner and four short simple setae along lateral margin; flagellar article 1 0.8 times longer than wide, with on broom, one UB, and four simple setae distally; ornamentation including setae and aesthetascs of following articles: 2:2:3:3:3:4:3:2:3:2:4:1:2:2:4.

Antenna ( Fig. 2C ) article 1 0.9 times longer than wide, with one UB distal seta; article 2 0.5 longer than wide, with one UB seta distally; article 3 1.4 times longer than wide, with three UB setae distolaterally, scale with one simple seta along lateral edge, five UB and three fine setae on distal region; article 4 0.7 times longer than wide, with two UB and three simple setae distolaterally.

Mandibles ( Fig. 3 ) pars molaris truncate, distal margin of grinding surface stepped, with four short simple setae, palp inserted on cuticular projection; article 1 ( Fig. 3A ) 2.4 times longer than wide, with three simple setae distally; article 2 2.3 times longer than wide, with two robust serrate setae and four simple setae on distolateral margin; article 3 2.3 times longer than wide, with one robust apical seta and numerous simple setae along lateral margin; right mandible ( Fig. 3A ) pars incisiva with five cusps; lacinia mobilis absent, with 12 robust serrate setae; left mandible ( Fig. 3B ) pars incisiva with five cusps, lacinia mobilis and eight serrate setae below pars incisiva.

Labium ( Fig. 3C ) body divided into two lobes by deep medial incision, distal margin of each lobe with simple setae and many hairs.

Maxillula ( Fig. 3D ) lateral lobe with 12 robust serrate setae distally and numerous fine setae along inner margin, one simple seta present on distal margin; medial lobe with four serrate apical setae and fine setae along outer margin.

Maxilla ( Fig. 3E ) lateral two lobes each with three long simple and one serrate seta distally; medial lobe with ten robust serrate and numerous fine setae distally.

Maxilliped ( Fig. 3F ) basis 2.2 times longer than wide with four simple setae medially and one short simple seta on distolateral corner; endite 1.7 times longer than wide, with five fan-like, nine serrate, and one simple setae on distodorsal margin, five simple setae on distoventral margin, three coupling hooks proximomedially; epipodite 2.6 times longer than wide, distal end with one short seta, reaching to palp article 3; palp article 1 0.9 times longer than wide, with two simple setae on distomedial and distolateral corners; article 2 1.1 times longer than wide, with 18 simple setae on medial margin; article 3 0.8 times longer than wide, with 25 simple setae along medial and distomedial margin; article 4 3 times longer than wide, with six simple setae along lateral margin and 15 setae on distal margin; article 5 2.2 times longer than wide, with 16 simple setae distally.

Pereopods ( Figs 4–5 ) all coxae visible in dorsal view, each coxa with simple setae, ranging from one to two or three; pereopod I subchelate, carpus broadened at center; articular plate projected from distal margin of propodus partly covered dactylus of all pereopods.

Pereopod I ( Fig. 4A ) article L/W ratios 2.3:2.5:0.9:2.1:3.9:0.9; basis with two UB and ten simple setae; ischium with eight UB and 12 simple setae; merus with five UB and seven simple setae; carpus with seven UB and 19 simple setae, 19 robust setae along posterior margin; propodus with one UB and four simple setae distally, 22 short simple setae along anterior and posterior margins, proximoventral border serrated; dactylus armed with four simple setae.

Pereopod II ( Fig. 4B ) article L/W ratios 2.7:3.4:1.4:3.8:4.6:1.4; basis with four broom, seven UB, and 13 simple setae; ischium with six UB and 12 simple setae; merus with seven UB and nine simple; carpus with one broom, 15 UB, and 22 simple setae; propodus with one broom, 14 UB, and 39 simple setae; dactylus with three claws and four simple setae.

Pereopod III ( Fig. 4C ) article L/W ratios 2.6:2.8:1.3:3.2:4.1:1.4; basis with two broom, three UB, and nine simple setae; ischium with eight UB and seven simple setae; merus with five UB and eleven simple setae; carpus with one broom, nine UB, and 13 simple setae, distal edge covered with fine hairs; propodus with one broom, 11 UB, and 27 simple setae; dactylus with four simple setae.

Pereopod IV ( Fig. 4D ) article L/W ratios 2.8:1.8:1.4:2.5:3.9:1.3; basis with six broom, two UB, and seven simple setae; ischium with eight UB and three simple setae; merus with seven UB and seven simple setae; carpus with 19 UB and three simple setae, numerous fine hairs present along distal margin; propodus with one broom, seven UB, and 26 simple setae; dactylus with four simple setae.

Pereopod V ( Fig. 5A ) article L/W ratios 2.6:2.3:1.2:2.9:3.6:1.3; basis with three broom, three UB, and ten simple setae; ischium with nine UB and seven simple setae; merus four UB and 11 simple setae; carpus with seven UB and ten simple setae, distal margin covered with hairs; propodus with four UB setae; dactylus with four simple setae.

Pereopod VI ( Fig. 5B ) article L/W ratios 2.7:2.7:1.2:2.9:4.2:1.3; basis with one broom, one UB, and 11 simple setae; ischium with seven UB and five simple setae; merus with six UB and four simple setae; carpus with five UB and eight simple setae, hairs present along distal edge; propodus with one broom, six UB, and 14 simple setae; dactylus with four setae.

Pereopod VII ( Fig. 5C ) article L/W ratios 2.6:2.8:1.2:3.5:4.8:1.5; basis with two broom, three UB, and eight simple setae; ischium with four UB and five simple setae; merus with six UB and five simple setae; carpus with five UB and nine simple setae; propodus with one broom, six UB, and six simple setae; dactylus with four simple setae.

Pleopod I ( Fig. 6A, B ) 1.4 times longer than maximum wide (measured at broadest section of distal part); separated in half by medial stylet-guiding groove running from proximal end; proximolateral part rounded; distolateral edge of hyaline lamella angular, projecting laterally; each half of pleopod I with five simple setae on distoventral quarter, distomesial part with pair of small protrusions, several short setae along distal apex.

Pleopod II ( Fig. 6C ) protopod oval, 1.5 times longer than wide, 12 simple setae along distal apex; endopodal stylet, elongate, medially swollen, becoming narrower until distal tip without any ornamentation; exopod distal apex round, located below stylet distomedially in protopod.

Pleopod III ( Fig. 6D ) protopod 0.8 times longer than wide; endopod, suboval, 1.4 times longer than wide, with three plumose apical setae; exopod with two articles, article 1 4.9 times longer than wide, numerous hairs covering lateral margin, article 2 2.2 times longer than wide with nine apical setae.

Pleopod IV ( Fig. 7A ) protopod 0.6 times longer than wide; endopod 1.5 times longer than wide, distomesial tip protruded; exopod 3.1 times longer than wide, with lateral margin covered by hairs.

Pleopod V ( Fig. 7B ) ellipse, 1.7 times longer than wide, with distomesial protrusion.

Uropod ( Fig. 7C ) protopod 1.5 times longer than wide, with 21 UB setae; endopod 4.2 times longer than wide, slightly longer than exopod, with six broom, 13 UB, and 23 simple setae; exopod 4.6 times longer than wide, with 19 UB and 12 simple setae.

Sexual dimorphism of female: Pereonites 2–4 distinctly expanded than other pereonites, maximal body width in pereonite 3; antenna ( Fig. 2D ) article 1 same as in male; article 2 0.6 longer than wide, with one UB seta distally; article 3 1.3 times longer than wide, with three UB and one simple setae distolaterally, scale with one simple seta on lateral edge and seven simple setae on distal end; article 4 0.9 times longer than wide, with two UB and two simple setae distolaterally; article 5 4.2 times longer than wide, with one broom, nine UB, and 20 simple setae; article 6 6.2 times longer than wide, with three broom, four UB, and 41 simple setae; flagellum with 88 articles, article 1 longer than following articles, 1.4 times longer than wide; following articles rectangular, with 0–3 short simple setae; Pereopods longer; Operculum semi-circular, length 0.8 times longer than width, outer margin with numerous short setae.

Variability: No significant variability was observed among paratypes in the armature of any appendages except that segmentation of antennular flagellum showed subtle difference in L/W ratio among body segments.

Etymology: The new species is named after Dr. Kwang-Soo Kim, a polychaete researcher who contributed to this study by providing academic advice.

Identification key. This updated identification key to East Asian Janiralata species is derived from previous studies of Kim & Yoon (2021) and Kim et al. (2022). It has modifications with new species added.

Figures

FIGURE 2. Janiralata kwangsooi sp. nov., male. A habitus, dorsal, (NIBRIV0000911352) B antennula, dorsal, C antenna articles 1‒4, dorsal, D antenna, female, dorsal. Scale bar: A: 500 µm, B‒D: 100 µm.

FIGURE 3. Janiralata kwangsooi sp. nov., male. A right mandible, dorsal, (NIBRIV0000911353) B left mandible, dorsal, C labium, dorsal, D maxillula, dorsal, E maxilla, dorsal, F maxilliped, dorsal. Scale bar: 100 µm.

FIGURE 4. Janiralata kwangsooi sp. nov., male. A pereopod I, dorsal, (NIBRIV0000911354) B pereopod II, dorsal, C pereopod III, dorsal, D pereopod IV, dorsal. Scale bar: 100 µm.

FIGURE 5. Janiralata kwangsooi sp. nov., male. A pereopod V, dorsal, (NIBRIV0000911354) B pereopod VI, dorsal, C pereopod VII, dorsal. Scale bar: A: 500 µm, B‒D: 100 µm.

FIGURE 6. Janiralata kwangsooi sp. nov., male. A pleopod I, dorsal, (NIBRIV0000911355) B pleopod I, ventral, C pleopod II, dorsal, D pleopod III, dorsal. Scale bar: 100 µm.

FIGURE 7. Janiralata kwangsooi sp. nov., male. A pleopod IV, dorsal, (NIBRIV0000911355) B pleopod V, dorsal, C uropod, dorsal, D female operculum, (NIBRIV0000911356). Scale bar: 100 µm.