Biapertura lepida (Birge, 1982) Sinev, 2020

Sinev, Artem Y., 2020, Re-evaluation of the genus Biapertura Smirnov, 1971 (Cladocera: Anomopoda Chydoridae), Zootaxa 4885 (3), pp. 301-335 : 323-324

Biapertura lepida (Birge, 1982) comb. nov.

Birge 1982: 393–394, Pl. 13. Fig. 19. ( Alona ); Sinev 2013: 335–341, Fig. 4–7 ( Alona ).

Type locality. Madisson , Wisconsin, USA .

Type material. Non–existent.

Material studied earlier. See Sinev (2013) for the list of material from USA and for detailed description.

Short Diagnosis. Parthenogenetic female. Length of adult female 0.92–1.06 mm. Body ( Fig. 15G ) with height strongly increasing posteriorly; maximum height in the third fourth of the body; height/length ratio 0.52–0.6 in adults. Unlike in all other species of the genus, sculpture of valves as well-defined longitudinal lines. Postero-dorsal angle ( Fig. 15H ) with 9–12 groups of setulae, with 5–9 setules in each. Main head pores with PP about 1.2–1.5 IP in adults ( Fig. 15I ). Lateral head pores located about 0.7–0.9 IP distance from midline, at the level of anterior major head pore. Postabdomen ( Fig. 15J ) with convex postanal margin; maximum height after the postanal angle; length about 2.5 height; dorsal margin weakly convex in postanal portion and weakly concave to almost straight in anal one; distal part about 2.5–3 times longer than preanal one; postanal portion 2.5–2.8 times longer than anal one. Postanal margin ( Fig. 15K ) with 15–17 very slender denticles, each with 1–4 denticles along anterior margin. Postabdominal claw ( Fig. 15L ) with basal spine about 0.25 the length of the claw; unlike in all other species of the genus angle between spine and postabdominal claw itself about 15° only. Antenna ( Fig. 15M ) with basal segment of both branches 1.5 times longer than two others, subequal in length; spine on basal segment of exopodite signifi-cantly longer than middle segment; spines on apical segments as long as apical segments. Limb I with IDL seta 1 not claw-like, thin, about half length of seta 2 ( Fig. 15N ); seta e of endite 2 only slightly longer than seta f.

Male unknown.

Differential diagnosis. B. lepida clearly differs from all other species of the genus in postabdominal claw with basal spine almost parallel to the claw itself, and by IDL seta 1 being not claw-like, two times shorter than seta 3.

Distribution and ecology. East USA, known from Wisconsin and North Carolina. Ecological preferences unknown.

Figures

FIGURE 4. Biapertura affinis (Leydig, 1860) from Glubokoe Lake, Moscow Area, Russia. A–L, thoracic limbs of adult parthenogenetic female. A, limb I. B, IDL and ODL of limb I. C. inner setae of endites 1–2 of limb I. D, limb II. E, exopodite of limb III. F–G, inner and outer parts of inner portion of limb III. H, exopodite of limb IV. I, inner portion of limb IV. J–K, limb V and its gnathobase filter plate. L, limb VI. M, copulatory hook and IDL of thoracic limb I of adult male. (A–L, orig.; M, after Sinev et al., 2020)

FIGURE 5. Biapertura affinis (Leydig, 1860) from Klein Vaal River, Transvaal Province, Republic of South Africa, adult male. A, lateral view. B, postabdomen. C, distal portion of postabdomen. D, antennule. E, copulatory hook of thoracic limb I. F, IDL of thoracic limb I.

FIGURE 6. Biapertura kendallensis (Henry, 1919) from Ryan’s II Billabong, Bonegilla, east of Wodonga, Victoria, Australia. A–B, juvenile females of instar I and II. C–K, adult parthenogenetic female. C, lateral view. D, ventral margin of valves. E, setae of anterior group. F, setae of posterior group. G, posterior margin of valves. H, posteroventral angle of valves. I–J, head shields. K, head pores. L, ephippial female. M–N, juvenile males of instar I and II. O, adult male.

FIGURE 7 Biapertura kendallensis (Henry, 1919) from near Ryan’s II Billabong, Bonegilla, east of Wodonga, Victoria,Australia. A, juvenile female of instar I. B–I, adult parthenogenetic female. B, lateral view. C–D, same specimen in lateral and dorsolateral view. E, anterior portion of ventral margin of valves. F, head pores. G, postabdomen. H, postanal margin of postabdomen. I, postabdominal claw.

FIGURE 15. Biapertura martensi (Sinev, 2009). A–F, adult parthenogenetic female. A, lateral view. B, posteroventral angle of valves. C, head pores. D, postabdomen. E, antenna. F, IDL of thoracic limb. Biapertura lepida (Birge, 1892). G–N, adult parthenogenetic female. G, lateral view. H, posteroventral angle of valves. I, head pores. J, postabdomen. K, postanal margin of postabdomen. L, postabdominal claw. M, antenna. N, IDL of thoracic limb I. (A–F, after Sinev, 2009; G–N, after Sinev, 2013).