Ovalona setulosa ( Megard, 1967 )

Sinev, Artem Y., 2015, Revision of the pulchella - group of Alona s. lato leads to its translocation to Ovalona Van Damme et Dumont, 2008 (Branchiopoda: Anomopoda: Chydoridae), Zootaxa 4044 (4), pp. 451-492: 469-470

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Ovalona setulosa ( Megard, 1967 )

comb. nov.

VIII. Ovalona setulosa ( Megard, 1967)  comb. nov.

( Fig. 6View FIGURE 6. A – E H –L)

Megard 1967: 44–47, Fig. 23–28, Pl. I, Fig. 3View FIGURE 3 a, b ( Alona  ); Smirnov 1971: 376, Fig. 443 ( Alona  ); Chengalath & Hann 1981: 386, Fig. 33–39 ( Alona  ); Sinev 2009: 70–75, Fig. 6–8View FIGURE 6. A – EView FIGURE 7. A – BView FIGURE 8. A – D ( Alona  ); Sinev & Silva-Briano, 2012: Fig. 7View FIGURE 7. A – B F –J ( Alona  ).

Type locality. A pond on the crest of Chuska Mountains, New Mexico, about 5 miles N of Washington Pass, U.S.A.

Type material. Holotype. Parthenogenetic female at British Museum (Nat.Hist.), London, 1966.3. 21.7.

Material studied earlier. See Sinev (2009 b) for the list of material from USA and Sinev & Silva-Briano (2012) for the list of material from Mexico.

Diagnosis. Parthenogenetic female. General. Length of adult female 0.33–0.44 mm. Body regular oval, of moderate height, height/length ratio 0.64–0.67, maximum height at the middle. Ventral margin with about 35–45 setae. Postero-dorsal angle with about 80 setulae not organized into groups.

Head. Posterior part of headshield broadly rounded. Three major head pores with interrupted connections between them, PP = 0.3–0.4 IP. Lateral head pores minute.

Labrum. Labral keel of moderate width, with convex anterior margin and blunt or rounded apex, posterior margin of keel with two clusters of setulae.

Second abdominal segment without dense setulae. Postabdomen short and wide, weakly narrowing distally, length about 2.2–2.4 height. Ventral margin straight. Distal margin straight, distal angle right, with rounded tip. Dorsal margin with straight postanal portion and concave anal portion. Distal part 1.5 times longer than preanal, anal and postanal portion of similar length. Preanal angle well-defined, postanal angle weakly defined or not defined. 6–8 short marginal denticles on postanal margin and with 5–6 groups of setulae on anal margin. Sevennine wide lateral fascicles of setulae, with distalmost setulae longer than marginal denticles. Postabdominal claw of moderate length, equal in length to preanal portion of postabdomen. Basal spine about 0.25 length of claw.

Antennule with antennular seta about 1 / 2 length of antennule, arising at 2 / 3 distance from the base. Aesthetascs of different length, two longest of them of about 1 / 2 length of antennule.

Antenna with seta arising from basal segment of endopodite shorter than endopodite. Spine on basal segment of exopodite shorter than middle segment. Spines on apical segments of same length as apical segments.

Limb I with accessory seta about 1 / 4 length of ODL seta. Limb III with exopodite seta 3 being longest, seta 6 about 1 / 3 length of seta 3, setae 1 and 4 about 1 / 4 length of seta 3. Limb IV with epipodite with very short projection. Exopodite seta 3 longest, setae 1 and 2 about 2 / 3 length of seta 3; setae 5 and 4 about 1 / 2 and 1 / 3 length of seta 3; setae 6 shorter than seta 4. Flaming-torch setae with well-developed distal portion. Limb V with epipodite with short projection. Exopodite seta 4 four times shorter than seta 1.

Ephippial female. Body of same shape as in parthenogenetic female, postero-dorsal angle not expressed, ephippium yellow-brown.

Male. General. Length 0.29–0.32 mm. Body low oval, maximum height in the middle of the body, height/ length ratio 0.57–0.59. Ocellus smaller than eye.

Postabdomen short, narrowing distally, subrectangular in distal portion, dorso-distal angle broadly rounded. Preanal angle well-defined, postanal angle not defined. Distal part of postabdomen 1.3 times longer than preanal. Clusters of short setulae in place of marginal denticles, lateral fascicles of setulae same as in female. Postabdominal claw 1.5 times shorter preanal portion of postabdomen, basal spine of about 0.25 claw length.

Antennule with male seta arising at 1 / 4 length from tip, reaching to the end of antennule.

Limb I with IDL seta 1 absent, setae 2 and 3 short and thin, subequal in length, male seta curved, almost as long as seta 2. On ventral face of limb below copulatory brush, a row of 20–25 short thick setulae.

Full description. See Sinev (2009).

Differential diagnosis. O. setulosa  differs from all other species of setulosa  -group by morphology of main head pores; it is the only species of the group with both interpore connections interrupted. O. anamariae  , O. altiplana  O. kaingang  , and O. weinecki  have uninterrupted connections. O. anastasia  and O. azorica  have connected anterior and middle pore and completely lack connection between middle and posterior pores.

Distribution. Canada, USA, North Mexico and Central Mexican Plateau.