Pleuroxus jejuensis Jeong, Kotov & Lee, 2013, sp.nov.
Creators: name: Jeong, Hyun Gi
name: Kotov, Alexey A.
name: Lee, Wonchoel
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Branchiopoda
Diplostraca
Pleuroxus
Pleuroxus jejuensis

description: Pleuroxus jejuensis sp.nov.
(Figs 2,3)
Etymology. The taxon is named after its type locality, Jeju Island (South Korea).
Type locality. A puddle in the Daseong wetland (260 m. a.s.l.), Jeju Special Self-Governing Province, Republic of Korea. Geographic coordinates: 33.4343ºN; 126.7523ºE (Table 1).
Type material. Holotype. Parthenogenetic female, 0.45 mm, collected 29.11.2012, NIBRIV0000264815.
Paratypes. 3 females from the type locality, collected 29.11.2012, NIBRIV0000264816; 3 females from the type locality, collected 29.11.2012, NIBRIV0000264817; 20 females from the type locality, collected 14.02.2012, MGU Ml-124; the rest of numerous females from the type locality, collected 14.02.2012, AAK-M-2365 and collected 29.11.2012, HGJ 339a; 6 parthenogenetic females from Daseong stream itself (locality 2 in Table 1), collected 14.02.2012, AAK-M-2364.
Diagnosis. Parthenogenetic female. Body yellow-brownish, relatively opaque, height about 0.8–0.9 body length, postero-ventral angle broadly rounded, without any teeth. Body moderately compressed laterally, in anterior view with regularly curved dorsum, top of carapace not ridged at all. Head shield wide, with maximum behind the level of mandibular articulation, postpore distance less than interpore distance. A row of minute setules at posterior valve margin located submarginally. Postabdomen wide, preanal margin longer than anal margin, preanal and postanal angle expressed, postanal margin somewhat longer than anal margin, dorso-distal angle widely rounded and prominent distally. Postanal teeth thin, organized in groups of two members in distal portion and 4–6 members in proximal portion of postanal margin. Proximal basal spine three quarters size of distal one. Antenna I with a well-defined basal peg and six distal spines. All apical "swimming" setae of antenna II, as well as basal and distal lateral seta of endopod subequal in size. Thoracic limb I with a short accessory seta, inner distal lobe with thin first seta. Filter plate of gnathobase II with eight setae, in few cases 7 setae; filter plate III with 8 setae; filter plate IV with 6, rarely 7 setae; filter plate V with 4 setae. Size up to 0.45 mm.
Site Puddle in swampy area River (locality 2) Puddle in swampy area Remnants of the river
(type locality) (type locality) (locality 2)
Date 14.02.2012 14.02.2012 29.11.2012 29.11.2012
Collectors H.G. Jeong H.G. Jeong H.G. Jeong & A.A. Kotov H.G. Jeong & A.A.
Kotov
Latitude, N 33.4350 N 33.4342 33.4343 33.4348
Longitude, E 126.7518 126.7514 126.7523 126.7516
Description. Parthenogenetic female. General. Body yellow-brownish, relatively opaque. In lateral view body almost circular, high for the genus (body height/ body length about 0.8–0.9), maximum height in middle (Fig. 2 A). Dorsal margin evenly arched from tip of rostrum to postero-dorsal angle, which is ill-defined, posterior margin slightly convex, postero-ventral angle broadly rounded, without any teeth, ventral margin with a slight prominence in anterior half. Body moderately compressed laterally (Fig. 2 B), with regularly curved dorsum in anterior view, top of carapace is not ridged at all (Fig. 2 C). One to two parthenogenetic eggs in brood pouch.
Head with a long rostrum, protruding downward and posterior (Figs. 2 A, D). Ocellus somewhat smaller than compound eye, lies closer to base of antenna I than to compound eye. Head shield wide, with maximum behind the level of mandibular articulation, with posterior margin rounded (Figs. 2 E–F), rostrum without a terminal tubercle. Two major head pores; postpore distance 0.7–0.8 interpore distance (Figs. 2 E–F). Lateral head pores minute, normally located symmetrically to midline (Figs. 2 G–H).
Labrum with fleshy main body, small distal labral plate and a large medial labral keel, with well-defined apex, projecting beyond tip of rostrum (Fig. 2 D).
Valves with subparallel lines at the antero-ventral portion (Figs. 2 A, I–J). Ventral margin armed with numerous setae of different size in different regions. The antero-ventral margin naked (Fig. 2 J), anteriormost portion of ventral margin with plumose setae, all located exactly at the margin; following setae (Fig. 2 J) naked and with spines at their bases; setae in middle and posterior half of ventral margin longer, lacking spines, plumose (Figs. 2 K). A row of minute setules at posterior valve margin located submarginally (Figs. 2 L).
Postabdomen wide (Figs. 2 M–N), its ventral margin straight, preanal margin longer than anal margin, with a slight depression, anal margin concave, preanal angle prominent, postanal angle poorly expressed; postanal margin somewhat longer than anal margin, dorso-distal angle widely rounded and somewhat prominent distally; basis of claws bordered from postanal margin by a distinct depression (Fig. 2 N). Postanal teeth thin, organised in groups of two members in distal portion and 4–7 members in proximal portion of postanal margin, anal margin with a continuous row of fine setules. Laterally on postabdomen series of short, fine setules, normally distalmost fascicle containing slightly thicker setules. Postabdominal seta longer than preanal margin, with distal segment bearing long, rare setules (Fig. 2 N). Postabdominal claw approximately as long as anal margin, massive, evenly curved, with setules along ventral margin, and two basal spines, proximal one being in length three quarters of distal one (Fig. 2 O).
Antenna I small, length/diameter = 2.5, narrowing distally, with a well-defined basal peg (Figs. 3 A–B). Antennular sensory seta slender, approximately as long as half the antenna I, arising from the middle, without any prominences. Nine short aestetascs of slightly differing size, with six spine-like projections around them.
Antenna II (Fig. 3 C) relatively short, coxal part with two sensory setae (not represented in Fig. 3 C), basal segment robust, with a rudimentary distal spine. Antennal branches relatively elongated, endopod longer than exopod, all segments cylindrical, antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0–0–1. All apical "swimming" setae, as well as basal and distal lateral seta of endopod, subequal in size. Spine on proximal segment of exopod short. Exopod and endopod apical spines subequal in size (Fig. 3 C).
Maxilla I as a hillock with three setulated setae (Fig. 3 D).
Trunk limb I (Figs. 3 E–F). Distal portion of limb corm with a short accessory seta (Fig. 3 F, pointed with arrow), outer distal lobe (Fig. 3 F, ODL) bears a long terminal seta with distal segment unilaterally armed with minute setules, and a short naked lateral seta. Inner distal lobe (Fig. 3, IDL) with a fine, naked first seta, second and third setae subequal in size and similarly armed distally with short setules. Endite 3 with three posterior setae subequal in size (Fig. 3 E, a–c) and somewhat longer setulated anterior seta with a small sensillum near its base (Figs. 3 E & G, marked by 1). Endite 2 with three posterior setae (Fig. 3 E, d–f), and thin anterior seta (pointed with arrow, number 2) bilaterally armed with short setules distally (Fig. 3 H), a small sensillum near the latter. Endite 1 with thin posterior setae g–i, a short seta j, and anterior seta (with number 3) (Fig. 3 I), subequal in size with seta 2. Fascicles of thin setules on inner face of limb, plus bunches of longer, thicker setules arranged in five rows at ventral margin. Two ejector hooks, subequal in size. A remnant of maxillar process (Fig. 3 E, MPR) with a single seta.
Trunk limb II (Figs. 3 J–K). Exopodite small, subquadrangular, with a short seta. Inner portion of limb with eight scrapers (Fig. 3 J, 1–8), 1–2 longer and armed with fine setules, others armed distally with thin spinules, setae 6–8 the shortest. A system of small projections posteriorly to scrapers 1–4, and a small sensillum near scraper 4. Distal armature of gnathobase with a bunch of setules and four setae (Figs. 3 K), a bunch of setules distally to seta 1, and a bunch of fine setules basally. Filter plate II with eight setae, in few cases 7 setae.
Trunk limb III (Figs. 3 L–M). Exopodite sub-rectangular, with four distal setae (Fig. 3 L, 1–4) and three plumose lateral setae (5–7). Distal endite with three anterior setae (Fig. 3 M, 1–3), basalmost seta (3) stouter and shorter, small sensillae near bases of setae 2 and 3. Basal endite with four anterior setae (Fig. 3 M, 4–7), slightly increasing in size basally, armed with fine setules distally, a small sensillum near seta 4. On posterior surface, six soft setae (Fig. 3 L, a–f), bilaterally armed with fine setules. Gnathobase not clearly separated from basal endite. Distal armature of gnathobase with a large, bottle-shaped sensillum, three setae, and a bunch of setules (Fig. 3 M), filter plate III with eight setae.
Trunk limb IV (Figs. 3 N–O). Pre-epipodite rounded, setulated; epipodite ovoid (not represented in Fig. 3 N); exopodite wide, subovoid, with seven setae of unequal size (Fig. 3 N, 1–7). Inner-distal portion of limb IV with four marginal setae (Fig. 3 O, 1–4). Distalmost seta (Fig. 3 O, 2) short and stout, all setae setulated distally, with thick distal segments, a sensilla located near each setae 2 and 3. On posterior surface, four soft setae (Figs. 3 N, a–d). Distal armature of gnathobase with four setae (Fig. 3 N), filter plate with six, rarely seven setae.
Trunk limb V (Fig. 3P). Pre-epipodite setulated; epipodite subovoid, exopodite large, subovoid, with a single distal seta 1 and three lateral setae (2–4), distally to seta 1 there are two projections bearing long setules. Inner limb portion as elongated, flat lobe, with setulated inner margin, supplied with two setulated setae (Fig. 3P, 1 and 2). Distal armature of gnathobase as a single projection, filter plate V with four long, naked setae.
Size. 0.23–0.45 mm.
Ephippial female, male. Unknown.
Distribution and Ecology. Up to date, P. j e j u e n s i s sp. nov. is known from two close localities on Jeju Island. No similar species were found in nearest regions of China (Chiang & Du 1979), Far East of Russia (Kotov et al., 2011a–b), Japan (Uéno 1926, 1937; Tanaka 1994) and continental South Korea (Kotov et al. 2012). The species seems to be endemic of this island.
The information on localities is given in Tables 1–2. It is remarkable, that at two different dates P. jejuensis sp.nov. occurred both in the river and in the puddles from the swampy area. It means that it could be present in water bodies of different type. In November it co-occurred with six other species of cladocerans in stony pools (remnants of the almost dried Daseong river, Fig. 1 F). Unfortunately, our sampling covered only the winter season, no data are available on these localities in summer, i.e. at the monsoon time.
Site Puddle in swampy area River Puddle in swampy area Remnants of the river Date 14.02.2012 14.02.2012 29.11.2012 29.11.2012 Simocephalus cf. vetulus (O.F. Müller) +
Scapholeberis kingi Sars + Bosmina longirostris (O.F. Müller) + Acroperus harpae (Baird) + Alona costata Sars + Alonella cf. exigua (Lilljeborg) + Alonella excisa (Fischer) + Cyclopoida undet. + + + +
description: Published as part of Jeong, Hyun Gi, Kotov, Alexey A. & Lee, Wonchoel, 2013, A new species of the genus Pleuroxus Baird (Cladocera: Anomopoda: Chydoridae) from Jeju Island, South Korea, pp. 31-40 in Zootaxa 3666 (1) on pages 33-38, DOI: 10.11646/zootaxa.3666.1.3, http://zenodo.org/record/283837