Caecianiropsis goseongensis, Kim, Jeongho, Lee, Wonchoel & Karanovic, Ivana, 2019

Kim, Jeongho, Lee, Wonchoel & Karanovic, Ivana, 2019, A new interstitial species of the genus Caecianiropsis Menzies & Pettit, 1956 (Isopoda, Asellota) from Korea, ZooKeys 832, pp. 35-56 : 38-42

Caecianiropsis goseongensis sp. n. Figures 1, 2, 3, 4, 5, 6, 7, 8, 9

Type locality.

Shallow water of East Sea (Sea of Japan), Goseong, Gangwondo, Korea, 38°17'43.8"N, 128°33'15.1"E.

Material examined.

Holotype: adult male, (NIBRIV0000838292) completely dissected and mounted in lactophenol on eight slides; allotype: non-ovigerous female (NIBRIV0000838293) dissected on three slides; paratype 1: adult male (NIBRIV0000838294) dissected on three slides; paratype 2 adult male (NIBRIV0000838295) dissected on two slides; paratype 3: male used for SEM (NIBRIV0000838296).

Diagnosis.

Pleotelson 1.45 times longer than wide, 0.23 times of whole body, antennula with seven articles, article VI with one simple seta and two aesthetascs distally, article VII very tiny, with three simple setae and one elongate aesthetasc, male antenna with 29 articles of flagellum, left mandible with five serrate setae in spine low, maxillipedal palp with setal formula as follow: 2:12:7:8:10, pereopod I with setal formula as follow: 5:1:10:13:19:7, pereopod II with setal formula as follow: 8:5:8:11:14:5, distal margin of pleopod I with 38 setae, uropodal exopod 0.5 times of endopod. Female operculum with two setae on medial margin and six setae along distal apex.

Description of the male holotype.

Body (Fig. 1A): elongate, flattened in dorsal view, color of preserved specimens transparent, total length measured with paratype I 2.05 mm, length six times longer than wide, maximal body width in pereonite V 0.91 times of maximal width of pleotelson, setation of pereonites I‒VII as follows: 10: 10: 10: 8: 6: 6: 6.

Cephalon (Fig. 1B): 0.94 times longer than wide and 0.16 times of whole body, anterior margin wider than posterior one; rostrum slightly wider than antennular article I.

Pleotelson (Fig. 1C): 1.45 times longer than wide, 0.23 times of whole body, dorsal and lateral margin covered with many setae.

Antennula (Fig. 2A): seven articles, relative length ratios: 1: 0.97: 0.22: 0.17: 0.36: 0.24: 0.03; article I robust, 1.38 times longer than wide, lateral margin with three simple setae, distal margin with three simple and one broom setae; article II 0.48 times wider than article I 1.89 times longer than wide, with three simple and four broom setae; article III 1.1 times longer than wide, with two simple setae distolaterally; article IV 0.89 times longer than wide, with three simple and one broom seta distally; article V 2.58 times longer than wide, with three simple setae distolaterally; article VI 1.72 times longer than wide, one simple seta and two aesthetascs distally; article VII (Fig. 2B) smallest, with three simple and one elongate aesthetasc on distal end.

Antenna (Fig. 2C, D): six peduncle articles and 29 flagellar articles; article I with three mediolateral setae; article II 0.92 longer than wide, with one seta distolaterally; article III twice as long as wide, with four setae distally, rudimentary scale on lateral margin with two setae; article IV 0.71 times longer than wide, with three simple mediolateral setae; article V 3.55 times longer than wide, with 14 simple setae; article VI longest, 5.68 times longer than wide, with 25 simple setae; flagellar article I longest, 2 times longer than wide, with two simple setae distally, setal formula of articles from 2 to 29 as follows: 3: 3: 4: 1: 3: 2: 4: 2: 3: 8: 3: 1: 4: 2: 3: 3: 4: 4: 3: 3: 4: 3: 4: 3: 4: 3: 3: 3.

Maxilliped (Fig. 2E): epipodite, narrow, 3.56 times longer than wide, distal end reaching to palp article II; basis 3.8 times longer than wide; endite width 0.83 times of palp article II, two proximomedial coupling hooks, distal margin covered with numerous fine setae, with six simple setae, three serrated setae, and one fan seta (Fig. 2F); palp relative length ratio: 1: 1.77: 1.14: 1.63: 0.91, article I 0.55 times longer than wide, with two simple setae on both distal corners; article II quadrangular, 0.95 times longer than wide, 1.9 times longer than article I, with eleven simple long setae on distomedial margin and one short seta on distolateral corner; article III 1.13 times longer than article I, tapering distally, with six simple long setae along medial margin and one seta on distolateral corner; article IV 2.14 times longer than wide, with eight simple setae on distal margin; article V with eight simple and two robust setae on distal end.

Mandible (Fig. 3A, B): body robust, curved inwardly; left mandible (Fig. 3A) pars incisiva with four cusps; lacinia mobilis much smaller than that of right mandible, with three denticulate, robust spines and three serrate setae (Fig. 3E); pars molaris truncate, missing grinding surface, distal tip blunt, with two apical setae; right mandible (Fig. 3B) pars incisiva with five (Fig. 3H), lacinia mobilis smaller than pars incisiva, with five cusps, five serrate setae located below lacinia mobilis, proximal part of setae covered by fine numerous setae, pars molaris with two apical setae (Fig. 3G); palp (Fig. 3A) 0.97 times of body length, inserted on cuticular projection; article I with one seta distally, 3.58 times longer than wide; article II robust, 1.89 times longer than wide, length 0.83 times of article I, maximal width 1.58 times of article I, median margin swollen, with three serrate setae distolaterally, article III laterally curved with ten serrate setae on inner margin.

Hypopharynx (Fig. 3C): deep medial incision separating two lobes, much of hairs on distal margin of each lobe.

Maxillula (Figs 3D, F): inner endite shorter and more slender than outer one, with one short setae and several hair-like elements on distal apex, along lateral margin with spiny row; outer endite with 12 robust setae on distal margin, most denticulate, some two-sided serrate, along lateral margin with long simple setae.

Maxilla (Fig. 4A): all rami similar in length, with four serrated setae on distal end of each; mesial ramus coalescent with basis, much thicker than others, with eleven strong setae distally and some of them denticulate; median ramus with four pectinate setae and lateral one with three pectinate setae distally, all rami with fine simple setae along medial margin.

Anterior pereopods (Figs 4B, C, 5A, B) inserted on pereon anterolaterally, relative length ratio: 1: 1.12: 1.12: 1.01; width ratio of carpus and propodus: 1: 0.87: 0.87: 0.73/ 1: 0.6: 0.6: 0.55; L/W ratio of articles: basis (2.03: 3.03: 2.97: 2.86), ischium (2.27: 2.57: 2.65: 2.05), merus (1.4: 1.52: 1.75: 1.52), carpus (2.52: 4.21: 3.71: 3.9) propodus (3.21: 6.83: 6.08: 6.17), dactylus (1.5: 1.48: 1.55: 1.45); pereopod I with minute coxa hardly discernable in lateral view (Fig. 9A); coxae of pereopods II‒IV clearly visible in lateral view with small simple seta; dactylus of pereopods II‒IV partly covered by articular plate projected from distal margin of propodus.

Pereopod I (Fig. 4B) basis with three broom and two simple setae; ischium with one seta on dorsal margin; merus with four setae of different lengths on distodorsal corner and five setae on ventral margin; carpus dorsal margin with four setae, two UB setae on ventral margin with six simple setae of different lengths, ventral margin with hairs; propodus with eight simple setae along dorsal margin, ventral margin with seven simple and four UB setae; dactylus tapering distally, dorsal margin with four setae of different lengths, ventral side with three setae, two claws on distal apex with different lengths.

Pereopod II (Fig. 4C): basis dorsal margin with four simple and three broom setae and with one short seta on distal corner; ischium with five simple setae, merus distal margin with eight setae of different lengths; carpus dorsal margin with three simple and one broom seta, ventral margin with five simple and two UB setae; propodus with eight setae along dorsal margin and two simple and four UB setae along ventral margin; dactylus (Fig. 4D) with two claws and five simple setae.

Pereopod III (Fig. 5A): basis dorsal margin with three simple and one broom setae, and with one short seta on distal corner; ischium with five simple setae; merus distal margin with eight setae of different lengths; carpus dorsal margin with one broom and three simple setae, ventral margin with one UB and four simple setae; propodus dorsal margin with seven simple and one broom setae, four simple and three UB setae along ventral margin; dactylus (Fig. 5C) with two claws and six simple setae.

Pereopod IV (Fig. 5B): basis with three simple and five broom setae on dorsal margin, one short seta on distal corner; ischium with five simple setae on distal margin; merus with seven setae of different length on distal margin; carpus dorsal margin with four simple and one broom seta, ventral margin with three simple and one UB seta; propodus dorsal margin with seven simple and one broom seta, four simple and three UB setae along ventral margin; dactylus (Fig. 5D) with two claws and six simple setae.

Posterior pereopods (Figs 6A, B, 7A) inserted on pereon posterolaterally, relative length ratio in comparison to pereopod I, 1: 1.12: 1.27: 1.31; L/W ratio of articles: basis (3.1: 3.11: 3.08), ischium (2.86: 2.72: 2.72), merus (1.48: 1.67: 1.76), carpus (3.43: 4.17: 4.42) propodus (3.53: 6.69: 5.56), dactylus (1.45: 1.56: 1.45); coxae of pereopods V‒VII approximately twice as wide as those of anterior pereopods, clearly visible in lateral view with two simple setae; dactylus partly covered by articular plate projected from distal margin of propodus.

Pereopod V (Fig. 6A): basis dorsal margin with six simple and five broom setae, ventral margin with two setae; ischium with six simple setae; merus with seven setae of different length; carpus with six simple, one broom seta and one UB seta along margin; propodus with relatively bigger UB seta protruding medially, with seven simple setae, one broom seta, and one UB seta; dactylus (Fig. 6C) with two claws and four simple setae distally.

Pereopod VI (Fig. 6B): basis with seven simple three broom setae; ischium with five simple setae; merus with nine simple setae on distal margin; carpus with six simple, one broom, and one UB setae, spiny row along dorsal margin; propodus with seven simple setae, one broom seta, and two UB setae; dactylus (Fig. 6D) with two claws and six simple setae distally.

Pereopod VII (Fig. 7A): basis with six simple three broom setae, ischium with four setae; merus with nine simple setae on distal margin and three of them much elongate; carpus with nine simple, one broom seta, and two UB setae, spiny row along dorsal margin; propodus with six simple, one broom, and three UB setae; dactylus (Fig. 7D) with two claws and six simple setae.

Pleopod I (Fig. 7B): reaching posterior margin of pleotelson, consisting of two coalescent halves, elongate, 3.86 times longer than maximum wide (measured at widest section of proximal part); proximal part enlarged and becoming narrower until half of total length and subsequently broaden distally, 3.86 times longer than maximum wide (measured at widest section of proximal part); separated in half by medial stylet-guiding groove running from triangular opening on proximal part of medial groove, distolateral edge of hyaline lamella angular, projecting laterally; each distomedial lobe tapering distomedially, with ten simple setae distolaterally; distodorsal margin with 22 simple setae; 30 simple setae along distal apex, two distodorsal protrusions developed proximally (Fig. 7C).

Pleopod II (Fig. 8A): sympod elongate, 2.7 times longer than wide; endopodal stylet, elongate, coiled in relaxed position, over 3 times longer than sympod, proximally robust but becoming narrower until distal tip, distal end of sperm duct consisting two rami (Fig. 10H) without ornamentation; exopod distal apex round, located below stylet, distomedially in sympod.

Pleopod III (Fig. 6C): sympod 1.61 times longer than wide; endopod length 0.67 times of sympod, 2.17 times longer than wide, suboval, with ornamentation like turtle shell shape, and with three plumose setae along distal margin; exopod two-segmented, basal segment 5.37 times longer than wide, with hairs along lateral margin, apical segment tapering distally, with one simple seta.

Pleopod IV (Fig. 7B): sympod, pentagonal, exopod 1.6 times longer than endopod, exopod tip not reaching to endopod tip; without ornamentation, exopod proximally curved, with distal seta.

Pleopod V (Fig. 7C): 3.16 times longer than wide, without rami and ornamentation, distal apex rounded.

Uropods (Fig. 7D): length 0.92 times of pleotelson; sympod robust, 3.5 times longer than wide, with 19 simple setae, most of setae on medial margin; endopod length 1.51 times of sympod with 24 simple and nine broom setae; exopod 0.5 times of endopod, with 12 simple setae.

Penial papillae (Fig. 10D, E): pointed distally, located ventrally on posteromedial margin of pereonite VII.

Sexual dimorphism of female.

Body (Fig. 9A): coxae of pleonites VI and VII visible in dorsal view.

Antennula (Fig. 9A): with five articles.

Antenna (Fig. 9B): with 25 flagellar articles.

Maxillipedal palp (Fig. 9C): article I with one seta distomedially, article II with four setae distomedially, article III with four setae, article IV with five setae, article V with seven setae distally.

Female operculum (Fig. 8D): 1.32 times longer than wide, two simple setae on dorsal surface, six setae along distal apex.

Etymology.

The new species is named after the type locality, Goseong, Gangwondo, Korea.