Flavalona cheni Sinev & Dumont 2016, comb. nov.

Flavalona cheni (Sinev, 1999) comb. nov.

Fig. 3A

Alona cheni Sinev, 1999a: 142–146, figs 8–10.

Alona cheni – Maiphae et al. 2008: 6, fig. 3.

Alona costata – Idris 1983: 106–108, fig. 50.

Alona setigera – Chen & Peng 1993: 19, figs 1–5.

Diagnosis

Female

Length of adult up to 0.47 mm. Body regular oval, maximum height at the middle of body, height/ length ratio ca 0.6. Valves from previous molts not retained. Posteroventral angle without setules protruding beyond valve margins. Ventral margin with ca 45 setae. Valves covered by thin, sparsely spaced longitudinal lines.

Eye larger than ocellus. Rostrum short, broadly rounded. Posterior margin of head shield broadly rounded. Three major head pores (Fig. 3A), middle pore slightly smaller than others, located near posterior pore. Connection between middle and posterior pore wide, connection between middle and anterior pore narrow. PP ca 0.7–0.9 IP. Lateral head pores of ca 0.9–1.2 IP length, lateral pore pockets semicircular, with depth ca 0.5 of pore length. Labral keel without denticles.

Postabdomen truncated, length 2.2–2.4 heights. Distal margin straight, distal angle prominent, acute with rounded tip. Dorsal margin weakly convex in preanal part, concave in anal part, straight in postanal part. Distal part of dorsal margin 3 times longer than preanal one, with preanal portion 1.3–1.5 times longer than anal one. Preanal and postanal angles weakly defined. Postanal margin of postabdomen provided with 10–14 marginal denticles. Anal margin with 4–5 clusters of marginal setules. 10–12 lateral fascicles of setules, distal setules in fascicle being longest. Postabdominal claw of moderate length, 1.5 times longer than preanal portion of postabdomen. Basal spine ca 0.15 of length of claw.

Antennule with longest aesthetasc of ca 2/3 the ength of antennule. Scrapers of limb II of similar morphology. Exopodite III with seta 6 of ca 2/3 the length of seta 3. Exopodite IV with seta 3 being

longest, setae 1–2 slightly shorter, setae 4–6 ca 0.4 length of seta 3. Epipodites IV without process. Exopodite V strongly bilobed. Epipodite V with processes as long as epipodite itself.

Male

U nknown.

Differential diagnosis

Flavalona cheni comb. nov. differs from F. setigera comb. nov. in having three major head pores; from F. costata comb. nov. and F. margipluma comb. nov. by the morphology of lateral head pores, with semicircular pore pockets about half the depth of pore length; from F. natalensis comb. nov. in the typical costata -like sculpture of the valves; from F. weltneri comb. nov. in the shape of its postabdomen.

Type material

Holotype

Parthenogenetic ♀, Zoological Museum of Moscow State University, ML-05.

Paratypes

Two dissected parthenogenetic ♀♀ on slides, Zoological Museum of Moscow State University, Ml-06, ML-07.

Material studied earlier

See Sinev (1999a) for list of material from India and Maiphae et al. (2008) for a list of material from Thailand.

Type locality

INDIA: Aiwa reservoir, Ahmedabad.

Distribution

India, South-East Asia and China (Sinev 1999a; Maiphae et al. 2008; Idris 1983), northernmost record in China from Wuhan province (Chen & Peng 1993).