Kurzia brevilabris Rajapaksa & Fernando, 1986

Sinev, Artem Y. & Semenyuk, Irina I., 2021, Males and ephippial females of Oriental Chydoridae (Cladocera: Anomopoda) from Cat Tien National Park, South Vietnam, Zootaxa 4941 (3), pp. 381-398 : 389

Kurzia brevilabris Rajapaksa & Fernando, 1986

Uncommon species in Cat Tien ( Sinev & Korovchinsky 2013). Species was found in most samples from localities 1 and 7; single adult male was found in locality 1 on 05.12.2017. Morphology of species fully agrees with its initial description ( Rajapaksa & Fernando 1986), although in this description male appendages do not appear detailed enough.

Male. Body ( Fig. 4J ) high, oval, with maximum height before midline, height/length ratio about 0.8. Valves covered by weakly developed linear sculpture. Ocellus and eye of same size as female. Rostrum ( Fig. 4L ) strongly curved, only slightly longer than antennule; in frontal view its distal half very narrow, with parallel margins; tip of rostrum bilobed.

Postabdomen ( Fig. 4K ) long and narrow, unevenly narrowing distally, with weakly defined, obtuse ventrodistal angle. Ventral margin of postabdomen almost straight; dorsal margin almost straight in anal portion and clearly concave in postanal portion. Maximum height at preanal angle. Dorsodistal angle well defined. Sperm duct openings located at end of postabdomen. Preanal and postanal angles weakly defined. Distal part of postabdomen 3–3.5 times longer than the preanal one; postanal portion 2.5 times longer than anal one. Clusters of very short setulae in place of marginal denticles; lateral fascicles of setulae, unlike those of female, consisting of thin setulae of equal thickness, being central setulae longest. Postabdominal claw long and narrow, curved, slightly longer than preanal margin of postabdomen; length of basal spine less than the width of claw base.

Antennule ( Fig. 4L ) very long and narrow; length about 3.5 widths, with 9 terminal and 3 lateral aesthetascs; two of lateral aesthetascs located near base of male seta, and one on the opposite side of antennule. Longest terminal aesthetascs of about 2/3 length of antennule. Male seta thin, arising at 1/4 length from tip, about 1/4 of antennule length.

Thoracic limb I ( Fig. 4M ) stouter than that of female, with short U-shaped copulatory hook, two times shorter than the limb itself. IDL seta 1 thin, about half length of seta 3; setae 2 and 3 curved, of similar length, thinner and shorter than in female, each bearing 2 strong spinules at the middle, followed by thin setulae; male seta almost straight, as long as seta 3. Copulatory brush seta 2 times shorter than male seta. A row of about 25 short setulae on ventral face of limb under copulatory brush seta. Inner seta 1 of endite 3 more slender than in female, longer than other setae of endite 3.

Size. In single studied adult male, length was 0.43 mm, height 0.35 mm.

Figures

FIGURE 4. Karualona karua (King, 1853) from locality 4. Ephippial female: A, lateral view (sculpture of valves not shown). Adult male: B, lateral view (sculpture of valves not shown); C–D, postabdomen; E, antennule; F, thoracic limb I; G, IDL of thoracic limb I; H–I, copulatory hook of thoracic limb I. Kurzia brevilabris Rajapaksa et Fernando, 1986 from locality 1. Adult male: J, lateral view; K, postabdomen; L, antennule and rostrum in frontal view; M, thoracic limb I.