Cleantiella ampliscutula, Kim & Jung & Yoon, 2020

Kim, Sung Hoon, Jung, Tae Won & Yoon, Seong Myeong, 2020, Two new species of idoteid isopods (Crustacea, Isopoda, Idoteidae) from Korea, Zootaxa 4858 (2), pp. 186-200 : 187-192

Cleantiella ampliscutula sp. nov.

Figs 1–3

Material examined. Holotype: ♂, 10.5 mm, Hongdo Island (34°40´09″N, 125°10´50″E), Hongdo-ri, Heuksan-myeon, Sinan-gun, Jeollanam-do, Korea, 19 June 2018, 10 m, SCUBA diving, NIBRIV0000862800.

Paratype: 1 ♀ (ovigerous), 1♀ (non-ovigerous), same data as holotype .

Additional material: Korea: 1 ♀ (juvenile), Sosambudo Island (34°02´23″N, 127°21´43″E), Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanam-do, Korea, 27 June 2017, 15 m, SCUBA diving; 1 ♂ (juvenile), Sangbackdo Iland (34°03´4″N, 127°35´13″E), 28 June 2017, 15 m, SCUBA diving; 1 ♂ (juvenile), Yeondo Island, Yeondo-ri, Nam-myeon , Yeosu-si (34°26´31″N, 127°48´43″E), 29 June 2017, 10 m, SCUBA diving; 1 ♀ (juvenile), Maejuk-ri Hansan-myeon, Tongyeong-si , Gyeongsangnam-do (34°39´05″N, 128°34´28″E), 19 May 2014, 7 m, SCUBA diving .

Diagnosis. Cephalon with median projection dorsally; anterior margin concave; pereonite 1 expanding to anterolaterally; coxal plate 1 fused to pereon; coxal plates 2–7 triangular and distinct dorsally; pleon without articulating pleonite, with 3 partial sutures dorsally; pleotelson widening posteriorly on lateral margin and with rounded apex. Flagellum of antenna single-articled. Maxillipedal palp 4-articled.

Description of holotype male. Body ( Fig. 1A ) 10.5 mm, 2.9 times as long as wide, dorsoventrally flattened. Cephalon 0.5 times as long as wide, with median projection dorsally; anterior margin slightly concave; posterior margin partly immersed in pereonite 1; eye small, positioned to lateral margin of cephalon. Pereonites about 0.7 times as long as total body length, smooth; pereonite 1 shortest, expanded anterolaterally; pereonites 2–5 subequal to each other in length; pereonites 6 and 7 slightly shorter than former in length. Coxal plates visible dorsally, triangular; plate 1 fused to pereonite; plates 2–7 distinct; plates 6 and 7 larger than former. Pleon about 0.4 times as long as body in length, consisting of single segment possessing 3 partial sutures dorsally; pleotelson widening posteriorly on lateral margin; apex rounded.

Antennula ( Fig. 1F ) short, reaching second peduncle of antenna, composed of 3 peduncular articles and singlearticled flagellum; peduncular article 1 globular, larger than others; article 2 small, square, with 4 penicillate setae at anterodistal angle; article 3 slightly longer than article 2, with 4 short simple setae; flagellum oval, with 7 aesthetascs and 19 simple setae along with lateral margin. Antenna ( Fig. 1G ) consisting of 5 peduncular articles and single-articled flagellum; peduncular articles sequentially longer in length; flagellum with 2–3 pairs of simple setae laterally and distally.

Left mandible ( Fig. 1H ), incisor strongly 3-toothed; lacinia mobilis 4-toothed, with 3 serrate setae; molar process rounded, with numerous simple setae. Right mandible ( Fig. 1I ), incisor 4-toothed; lacinia mobilis 3-toothed, with 2 serrate setae; molar process rounded, with numerous simple setae.

Maxillula ( Fig. 1J ) with fine setae laterally; inner lobe with 3 plumose setae on apical margin; outer lobe with 6 smooth robust setae and 2 denticulate setae apically. Maxilla ( Fig. 1K ) composed of 3 lobes; inner lobe with 8 plumose setae apically, numerous simple setae subapically; mesial lobe with 5 denticulate setae apically; outer lobe with 3 denticulate setae distally. Maxilliped ( Fig. 1L ), endite reaching to half of palp article 3, with 4 stout spines and 4 plumose setae on apical region, 1 coupling hook on inner margin; palp 4-articled; article 1 small, oblong; article 2 wider than article 1, triangular; article 3 rectangular; articles 4 and 5 fused, oval; articles 2–5 with simple setae on inner margin.

Pereopod 1 ( Fig. 2A ) slender; basis 2 times longer than ischium; ischium oblong, 1.8 times longer than wide; merus almost square, with 2 robust simple setae on inferior margin; carpus shorter than merus, triangle, with 5 robust setae on superodistal angle; propodus rectangular, with 11 comb setae on palmar surface, 11 robust setae along with inferior margin, 1 penicillate seta on superodistal angle; dactylus bi-unguiculate, with simple setae distally.

Pereopod 2 ( Fig. 2B ), basis almost 2 times longer than ischium; merus almost square; carpus smaller than merus, with 4 robust setae; propodus oblong, with 7 robust setae proximally, 3 simple setae distally, 1 short simple seta and 1 penicillate seta on superodistal angle; dactylus bi-unguiculated, with simple setae on distal end.

Pereopods 3–7 ( Fig. 2 C–G) similar to pereopod 2; basis with 0 or 2 penicillate setae on superior margin; ischium about 0.4 times as long as basis; merus and carpus almost square; carpus with robust setae on superodistal angle; propodus with robust setae proximally, simple setae distally, simple setae and penicillate seta on superodistal angle; dactylus bi-unguiculate, with 2–6 simple setae on distal end.

Penes ( Fig. 1D, E ) paired, not fused proximally.

Pleopod 1 ( Fig. 3A ), protopod almost square, with 4 coupling hooks on inner margin and 2 plumose setae on outer margin; rami subequal in length, with numerous plumose setae distally and laterally; plumose setae shorter than rami in length.

Pleopod 2 ( Fig. 3B ), protopod rectangular, with 2 simple setae on inner margin, 2 plumose setae on outer margin; exopod slightly shorter than endopod, with numerous plumose setae on lateral and apical margin; endopod with 10 plumose setae distally. Appendix masculina ( Fig. 3C ) longer than rami in length, with serrated margin on distal region; apex rounded.

Pleopod 3 ( Fig. 3D ), protopod square; exopod articulated, tapering distally, with 9 plumose setae on distal end, simple setae on lateral margin; endopod naked, slightly longer than exopod in length.

Pleopod 4 ( Fig. 3E ), protopod globular to square; exopod articulated, tapering distally, with short simple setae along with lateral margin; endopod naked, slightly longer than exopod.

Pleopod 5 ( Fig. 3F ) resembles pleopod 4; slightly wider than pleopod 4.

Uropod ( Fig. 3G ) uniramous; protopod about 2 times longer than wide, with 2 plumose setae distally; endopod triangle, 0.4 times as long as protopod; apex with slightly sinuous.

Paratype ovigerous female. Body ( Fig. 1B ) 13.1 mm in length, 3.2 times as long as wide, with slightly convex lateral margin; pereonite 3 widest; coxal plates smaller than male′s coxal plates.

Distribution. Korea (Southern coast of the Korean Peninsula).

Remarks. Among Cleantiella species, Cleantiella ampliscutula sp. nov. can be readily distinguished from C. isopus , the type species of the genus, by the shape of pereonite 1 (expanding to anterolaterally in the former vs. parallel in the latter), the pleon (with three partial sutures in the former vs. one articulating pleonite and two partial sutures in the latter), and the shape of the pleotelson (widening posteriorly on lateral margin in the former vs. parallel in the latter) ( Miers 1881; Kwon 1986).

Cleantiella ampliscutula sp. nov. is similar to C. strasseni in terms of pereonite 1 expanding anterolaterally, the pleotelson widening posteriorly, and the pleonite possessing three partial suture lines. However, C. ampliscutula sp. nov. differs from C. strasseni by having the smaller body in length (10.5 mm in the former vs. 17.5 mm in the latter), the larger coxal plates, and a single articled flagellum (vs. five articled flagellum in the latter) ( Thielemann 1910; Kussakin 1982). The detailed comparison of Cleantiella species is presented in table 1.

Etymology. The specific name, ampliscutula , originates from the combination of the Latin words amplius, meaning “larger,” and scutula, meaning “plate.” This name refers to the shape of the coxal plates that are more developed to triangular form.

Figures

FIGURE 1. Cleantiella ampliscutula sp. nov., holotype, male (A, D–L) and paratype female (B, C). A, Habitus, dorsal view; B, Habitus, ovigerous female; C, Habitus, non-ovigerous female; D, Pleon, ventral view; E, Penes; F, Antennula; G, Antenna; H, Left mandible; I, Right mandible; J, Maxillula; K, Maxilla; L, Maxilliped. Scale bars: A–C = 2 mm, D, G = 0.5 mm, E, F, H–L = 0.2 mm.

FIGURE 2. Cleantiella ampliscutula sp. nov., holotype, male.A, Pereopod 1; B, Pereopod 2; C, Pereopod 3; D, Pereopod 4; E, Pereopod 5; F, Pereopod 6; G, Pereopod 7. Scale bar: A–G = 1 mm.

FIGURE 3. Cleantiella ampliscutula sp. nov., holotype, male.A, Pleopod 1; B, Pleopod 2; C, Distal end of appendix masculina; D, Pleopod 3; E, Pleopod 4; F, Pleopod 5; G, Uropod. Scale bars: A, B, D–G = 0.5 mm, C = 0.1 mm.