Alonopsis aureolata Doolittle, 1912

Sinev, Artem Y. & Atroschenko, Margarita M., 2011, Revision of the genus Alonopsis Sars, 1862 and its position within Aloninae (Cladocera: Anomopoda: Chydoridae), Zootaxa 2800, pp. 1-17 : 13-14

Alonopsis aureolata Doolittle, 1912

Doolittle, 1912: 561–565, Pls. 42–43; Kubersky, 1977: 656–663, figs 3–20 ( americana ).

Type locality. Lake Sunapee, Sullivan County, New Hampshire, USA.

Holotype: immature female on a slide, U. S. National Museum (cat. 4# 44366), from Lake Sunapee, Sullivan County, New Hampshire, USA collected 22.04.1910.

Material. 37 parthenogenetic females from Sebago Lake, Maine, USA, 0 9.07.1966, coll. D. G. Frey, National Museum of Natural History (Washington DC, USA), Frey’s collection sample 1912.

Description. Parthenogenetic female. Body ( Fig. 6 A, C, E–F) height-length ratio about 0.59–0.63. Valves ( Fig. 6 G–H) and head as for genus. Head shield ( Fig. 7 A) with very short, broadly rounded rostrum. Head pores as for genus ( Fig. 7 B), IP/PP ratio about 1.5–2 in adult. Labrum as for genus ( Fig. 7 C–D). Thorax, abdomen and postabdomen ( Fig. 6 B, D, I–J) as for genus, same as in the previous species.

Antennule ( Fig. 7 F), antenna ( Fig. 7 D) and limb I ( Fig 7 G–H) same as in the previous species. Limb II ( Fig. 7 I) with scrapers 7 and 8 of similar size and shape, armed with 12–15 long, thick denticles. Limbs III ( Fig. 7 J–L) and limb IV ( Fig. 8 A–C) same as in the previous species. Limb V ( Fig. 8 D) as for genus, incursion between exopodite lobes as obtuse angle. Limb VI ( Fig. 8 E) with clusters of marginal setules in studied specimens of different proportions compared to the previous species.

Male. According to description of Kubersky (1977), body shape is similar to that of the previous species. Postabdomen ( Fig. 8 F) narrowing distally, but curved, with irregularly curved ventral margin and concave postanal margin, postanal angle defined, obtuse. Position of sperm ducts, armament of postabdomen, postabdominal claws similar to the previous species. Descriptions and drawings of antennule and limb I in description of Kubersky (1977) are somewhat vague. These structures appear to be similar to these of the previous species, but some differences possibly remain overlooked.

Size. In studied material, length of female of juvenile instar I— 0.41–0.46 mm; juvenile instar II— 0.50–0.57 mm; adult female— 0.62–0.89 mm.

Figures

FIGURE 6. Alonopsis aureolata Doolittle, 1912, USA, Maine, Sebago lake: A – B—juvenile female of instar I: A—habitus, lateral view, B—postabdomen; C – D—juvenile female of instar II: C—habitus, lateral view, D—postabdomen; E – H—parthenogenetic female: E – F—habitus, lateral view, G—valve, H—postero-ventral corners of valves, I – J—postabdomen. Scale bars: 0.2 mm for A, C, E – F, 0.1 mm for B, D, G, I – J, 0.05 mm for H.

FIGURE 7. Alonopsis aureolata Doolittle, 1912, USA, Maine, Sebago lake, parthenogenetic female: A—head shield, Bmain head pores, C – D—labrum, E—antennula, F—antenna, G – H—thorachic limb I in inner and outer view, I—limb II, Jexopodite of limb III, K – L—inner portion of limb III. Scale bars 0.1 mm for A and C – L, 0.05 mm for B.

FIGURE 8. Alonopsis aureolata Doolittle, 1912, USA, Maine, Sebago lake: A – E—thoracic limbs of parthenogenetic female: A – B—exopodite of limb IV and its setae 5 – 6, C—inner portion of limb IV, D—limb V, E—limb VI; F—outline of male postabdomen, after photo in Kubersky (1997), no scale bar. Scale bars: 0.1 mm for A, C – E, 0.05 mm for B.