Bleptus, Eaton, 1885

Tojo, Koji, Miyairi, Ken, Kato, Yuto, Sakano, Ayana & Suzuki, Tomoya, 2021, A description of the second species of the genus Bleptus Eaton, 1885 (Ephemeroptera: Heptageniidae) from Japan, and phylogenetic relationships of two Bleptus mayflies inferred from mitochondrial and nuclear gene sequences, Zootaxa 4974 (2), pp. 333-360 : 347

Key for the identification of Bleptus adults

For nymphs and eggs, we have not yet found any characteristics to differentiate between Bleptus michinokuensis sp. nov. and B. fasciatus ( Figs. 8−13 vs. 14).

1. A blackish band crosses the center of the fore wings ( Fig. 2 ), and both fore and hind wings feature a blackish distal marginal region ( Fig. 2 ). Constant thickness of penis lobes from the proximal through to the distal end, and the distal tip of these lobes is somewhat rectangular in shape ( Fig. 6 )..................................................... Bleptus fasciatus

- Fore wings without a blackish band ( Figs. 3–5 ), and fore and hind wings both without a blackish marginal region ( Figs. 3–5 ). Middle region of penis lobes thin, distal part of these lobes thick and bulbous in shape ( Fig. 5C–D )............................................................................................... Bleptus michinokuensis sp. nov.

Figures

FIGURE 8. Nymps of the newly described Bleptus michinokuensis sp. nov. Dorso-lateral view (A, C) and dorsal view (B). Arrowheads: 1st to 9th abdominal tergal spines on the median posterior margins of 1st to 9th abdominal segments, FWB: fore wing bud, MT: metathorax, II, VI–VIIG: 2nd, 6–7th abdominal gills, I−IX: 1st to 9th segments. Scale bars: B, C = 10 mm.

FIGURE 9. Nymphal head characteristics of the newly described Bleptus michinokuensis sp. nov. (1). Stereomicrographs (A, E) and SEM photographs (B−D, F−J). Ventral view of head (A), dorsal view of head (B). Enlargement of antenna (C) and its tip (D). Dorsal view of labrum (E). Ventral view of mouthparts (F). Enlargement of compound eye (G, H). Dorsal view of labrum (I) and its enlargement (J). An: antenna, CE: compound eye, Cllr: clypeolabrum, Cx: coxa, Fe: femur, Fl: flugellum, Gl: glossa, L1: fore leg, LbP: labial palp, Li: lingua, Lr: labrum, MxP: maxillary palp, Oc: ocellus, Pe: pedicel, Pgl: paraglossa, Sc: scape, Sli: superlingua, Tr: trochanter. Scale bars: A, B = 1 mm; C, E–G, I, J = 100 µm; D = 50 µm; H = 10 µm.

FIGURE 10. Nymphal head characteristics of the newly described Bleptus michinokuensis sp. nov. (2). Stereomicrographs (A, B) and SEM photographs (C−F) of mandible. Right (A) and left (B, D) mandibles. Enlargement of molar part (C, F) and incisor part (E). IIn: inner incisor, Md: mandible, Mo: molar, OIn: outer incisor. Scale bars: A, B, D = 500 µm; C, E, F = 100 µm.

FIGURE 11. Nymphal head characteristics of the newly described Bleptus michinokuensis sp. nov. (3). Stereomicrographs (A) and SEM photographs (B−D) of maxilla. Ventral view of maxilla (A, B) and its enlargement (C, D). Ga: galea, La: lacinia, LbP: labial palp, MxP: maxillary palp. Scale bars: A, B = 1 mm; C, D = 100 µm.

FIGURE 12. Nymphal head characteristics of the newly described Bleptus michinokuensis sp. nov. (4). Stereomicrographs (A, E) and SEM photographs (B−D, F−H). Ventral view of labium (A, B) and its enlargement (C, D). Ventral view of hypopharynx (E, F) and its enlargement (G, H). Gl: glossa, LbP: labial palp, Li: lingua, Lr: labrum, Pgl: paraglossa, Sli: superlingua. Scale bars: A, B, D, F = 500 µm; C, D, G, H = 100 µm.

FIGURES 13−14. Scanning electric microscopy (SEM) images of newly laid eggs of Bleptus michinokuensis sp. nov. (13A, B) and Bleptus fasciatus (14A, B). Lateral view of eggs (A, B) and enlargement of the egg surface showing micropyles (B). Mp: micropyle, MpO: micropylar opening, SG: sperm guide. Scale bars = 100µm (A), 10µm (B).

FIGURES 2–4. Photographs of Bleptus fasciatus and the newly described Bleptus michinokuensis sp. nov. Male of B. fasciatus in field (2); male of B. michinokuensis sp. nov. in field (3); male (4A) and female (4B) of B. michinokuensis sp. nov. in the laboratory. Scale bars: 4A, 4B = 10 mm.

FIGURES 5–6. Photographs of the newly described Bleptus michinokuensis sp. nov. and Bleptus fasciatus under an optical microscope. Wings (5A), lateral view of body (5B), lateral view (5C) and ventral view (5D) of terminus of abdomen including genitalia of a male of B. michinokuensis sp. nov.; ventral view (6) of the terminus of abdomen including genitalia of a male B. fasciatus. Ce: cercus, Fc: forceps, FW: fore wing, HW: hind wing, PnL: penis lobe, VIII−X: 8th to 10th segments. Scale bars: 5A, 5B = 10 mm.