Karualona kwangsiensis ( Chiang 1963 )

Tiang-Nga, Supatra, Sinev, Artem Y. & Sanoamuang, La-Orsri, 2020, High diversity of Cladocera (Crustacea: Branchiopoda) in a Ramsar site Lake Kud-Thing, Northeast Thailand, Zootaxa 4780 (2), pp. 275-290 : 283-285

Karualona kwangsiensis ( Chiang 1963)

( Figs. 5–6 )

Alona kwangsiensis Chiang 1963

Biapertura kwangsiensis Venkataraman 1999: 347–354 , figs. 1–4 and 11–14.

Karualona cf. kwangsiensis Kotov et al. 2013: 81–108 .

Karualona kwangsiensis Sinev 2016: 451–486 , fig. 11.

Studied material: 20 parthenogenetic females from Lake Kud-Thing (localities 1, 11, 12 and 14); 30 parthenogenetic females from four localities in Bueng Kan Province, including: (1) swamp, 18°15᾿09.98᾿᾿N, 103°51᾿37.18᾿᾿E, 153 m a.s.l., (2) Nong Jan Swamp , 18°11᾿38.84᾿᾿N, 103°45᾿03.79᾿᾿E, 160 m a.s.l., (3) Bang Bat River , 18°14᾿12.83᾿᾿N, 103°51᾿37.32᾿᾿E, 155 m a.s.l., (4) rice field, 17°48᾿59.89᾿᾿N, 103°19᾿27.16᾿᾿E, 162 m a.s.l.

Description. Parthenogenetic female: General. Length of adult parthenogenetic females 0.32–0.36 mm. In lateral view, body oval, maximum height before middle of the body ( Figs. 5 A–B, 6A). Postero-ventral angle of valves broadly rounded, armed with 4–5 long denticles; upper one or two are curved downward ( Figs. 5 G–I, 6B). Ventral margin of valves with about 45 setae ( Fig. 5N ). Sculpture of valves as well-developed longitudinal lines and polygons with fine line between them. Head relatively small, triangle-round in lateral view. Compound eye 2 times larger than ocellus. Head shield without prominent sculpture, covered by fine lines only. Rostrum short. Two major head pores with a narrow connection between them, distance from posterior pore to posterior margin of a head shield about 2 interpore distances. Lateral head pores minute, located at the level of anterior major pore ( Figs. 5 C–D, 6F). Labral keel of moderate width, with blunt apex ( Fig. 5E ).

Antennule of moderate size, length about 3.2 widths ( Fig. 5L ).

Antenna ( Fig. 5M ) with an antennal formula; setae 0-0-3/0-1-3, spines 1-0-1/0-0-1. Both branches with basal segments 1.5 times longer than others. One of the apical setae on endopodite much longer and thicker than others; apical setae of exopodite thin, of similar size. Spine on basal segment of exopodite short, about 1/3 length of middle segment. Apical spines of about 2/3 length of respective apical segments.

Thoracic limb I typical for the genus morphology ( Fig. 5F ).

Postabdomen ( Figs. 5 J–K, 6C–D) short, moderately wide, with the maximum height at the middle of postanal margin, narrowing basally in anal portion. Length about 2.5 heights. Ventral margin straight. Distal margin convex, distal angle broadly rounded. Dorsal margin convex in postanal portion and concave in the anal portion. Postanal portion 1.5–2 times longer than the anal one. Preanal angle well defined; postanal angle not defined. Preanal margin almost straight. Postanal margin with 7–9 groups of very small, short denticles; anal margin with 3–4 groups of short setulae. About 12 groups of lateral setulae; in postanal group, distal setulae much longer and thicker than others, being its length about 2 widths of postabdominal claw base. Postabdominal claw curved, slightly longer than the preanal margin. Basal spine very short.

Distribution and ecology. Karualona kwangsiensis was first described in China as Alona kwangsiensis by Chiang 1963, followed by India ( Venkataraman 1999, as Biapertura kwangsiensis ), placed to the genus Karualona by Van Damme et al. (2010) and then found in Laos ( Kotov et al. 2013). In Thailand, Karualona kwangsiensis was found in Lake Kud-Thing and Bueng Khong Long, as well as various rivers, swamps, and paddy fields. In Lake Kud-Thing it was encountered in limnetic zones associated with aquatic plants. Water variables of localities where K. kwangsiensis occurred were: temperature 26.8-34.9°C; pH 5.10-7.58; electric conductivity, 13-159 μS cm-1; total dissolved solid 8-79 mg L-1, and dissolved oxygen 1.8-9.0 mg L --1.

Taxonomic notes. Studied material fully agrees with early descriptions of Venkataraman (1999) and Sinev (2016). It clearly differs from two other Thai species, Karualona karua (King 1853) and Karualona serrulata Van Damme, Maiphae & Sa-ardrit 2013 by morphology of postero-ventral denticles of valves.

Figures

FIGURE 5. Karualona kwangsiensis (Chiang, 1963) from Bueng Kan Province, Thailand. A–B, adult parthenogenesis females in lateral view. C–D, head pores. E, labrum. F, limb I. G–I, postero-ventral of vales. J–K, postabdomen. L, antennule. M, antenna. N, ventral margin of vales.

FIGURE 6. Karualona kwangsiensis (Chiang, 1963), scanning electron microscopy of adult parthenogenetic females from Bueng Kan Province, Thailand. A, adult parthenogenesis females in lateral view. B, postero-ventral corner of valves. C–D, postabdomen. E, antenna. F, head pores.