Flavalona bicolor Sinev & Dumont 2016, comb. nov.

Flavalona bicolor (Frey, 1965) comb. nov. Fig. 6 A–F Alona bicolor Frey, 1965: 169–170, fig. 23–29. Alona bicolor – Frey 1969: 380–386, fig. 1–6. — Smirnov 1971: 363–365, fig. 421 — Sinev 2009: 60–65, fig. 1–3. Diagnosis Female Length of adult 0.50–0.62 mm. Body (Fig. 6A) regular oval, maximum height at the middle of body, height/length ratio about 0.65–0.72. Valves from previous molts often retained. Posteroventral angle without setules protruding beyond valve margins. Ventral margin with ca 60 setae. Valves without sculpture. Eye smaller than ocellus. Rostrum elongated, about 1.5–2 length of antennule, with rounded apex. Posterior margin of head shield (Fig. 6B) triangular with rounded apex. Three major head pores (Fig. 6C) of similar size, middle pore located closer to posterior pore. Connection between pores narrow. PP about 2 IP. Lateral head pores of about 0.4 IP length, lateral pore pockets shallow, with depth about ¼ of pore length. Labral keel (Fig. 6D) with 1–2 denticles on anterior margin. Postabdomen (Fig. 6E) truncated, length less than 2.5height.Distal margin convex, distal angle prominent, rounded. Dorsal margin weakly convex in preanal part, concave in anal part, and almost straight in postanal part. Distal part of dorsal margin 3 times longer than preanal one, anal and preanal portions of similar length. Preanal and postanal angles weakly defined. Postanal margin of postabdomen provided with 6–7 marginal denticles. Anal margin with 3–4 more slender denticles and 3–4 clusters of marginal setules. 10–14 lateral fascicles of setules, central setules in fascicle being longest. Postabdominal claw 1.5–1.7 times longer than preanal portion of postabdomen. Basal spine short, robust, about 0.15 length of claw itself. Antennule with longest aesthetasc as long as antennule. Limb II with scrapers 3 and 7 thicker and armed with more robust denticles than other. Exopodite III with seta 6 of about ⅔ length of seta 3. Exopodite IV with seta 3 being longest, setae 1–2 slightly shorter, setae 4–6 about half length of seta 3, seta 4 longer than setae 5–6. Epipodites IV–V without processes. Exopodite V oval. Male Length 0.51–0.53 mm. Body low oval, height/length ratio ca 0.55–0.59. Ocellus larger than eye. Postabdomen (Fig. 6F) evenly truncated. Preanal and postanal angles not defined. Distal part of postabdomen 3.5 times longer than preanal. Distal process long, ca ⅔–¾ length of claw. Distal clusters of marginal setules long, about two widths of postabdominal claw base. Postabdominal claw short, basal spine short, about 0.1 length of claw. Differential diagnosis Flavalona bicolor comb. nov. differs from all other species of the rustica -clade by an elongated rostrum, an ocellus larger than the eye, labral keel with blunt denticles and large IP/PP ratio (about 2). Males differ by their large size and long distalmost marginal setules at the end of the postabdomen. Type material Holotype Parthenogenetic female, British Museum (Nat. Hist.), London, 1963.6.24.1. Material studied earlier See Sinev (2009) for list of material from the U.S.A. Type locality UNITED STATES OF AMERICA: Goodwill Pond, Barnstable County, Massachusetts. Distribution and ecology Flavalona bicolor comb. nov. inhabits East Canada and North-East U.S.A. (Sinev 2009). According to Chengalath (1982, 1987), it is not found west of the Ontario- Manitoba border. It is found only in areas with rocky or sandy bottom, and is more rare than F. cf. rustica and F. cf. costata.

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