Biapertura martensi ( Sinev, 2009 ) Sinev, 2020

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

Biapertura martensi ( Sinev, 2009) comb. nov.

Sinev 2009: 42–48, Fig. 1–4 ( Alona ).

Type locality. Republic of South Africa, KwaZulu-Natal province, Giant Castle, The Lakes (29°14’31”S 29°33’2”Е), altitude: 1950 m.a.s.l. 26.03.1995 .

Type material. Holotype (parthenogenetic female) and paratypes (8 parthenogenetic females, 6 juvenile females of instar II, 2 juvenile females of instar I) at Zoological Museum of M. V. Lomonosov, Moscow State University ; access numbers Ml–51 and Ml-52, respectively.

Material studied earlier. See Sinev (2009) for the list of material from Republic of South Africa and Lesotho, and for detailed description.

Diagnosis. Parthenogenetic female. Length of adult 0.84–1.17 mm. Body irregular oval ( Fig. 15A ), with maximum height at the middle of the body, height/length ratio 0.6––0.65 in adults. Postero-dorsal angle with 4–5 groups of setulae, with 4–6 setulae in each ( Fig. 15B ). Main head pores with PP about 2.5–3 IP in adults ( Fig. 15C ). Lateral head pores located about 1.5 IP distance from midline, at the level of anterior major head pore. Postabdomen ( Fig. 15D ) of moderate length and width, narrowing distally in postanal portion; length about 2.5 height; dorsal margin almost straight in postanal portion and weakly concave in anal one, with distal part about 2.5 times longer than preanal one, and with postanal portion 2.6–2.8 times longer than anal one; postanal margin with 15–17 well–developed moderately massive denticles, each with 1–6 denticles along anterior margin. Postabdominal claw with basal spine about 0.3–0.45 of the claw length. Antenna ( Fig. 15E ) with basal segment of endopodite longer than two others; middle and distal segments of similar length; exopodite with basal and distal segments of similar length; middle segment being slightly shorter than two others. Spine on basal segment of exopodite much shorter than middle segment. Spine on apical segment of exopodite as long as apical segment; spine on apical segment of endopodite shorter than apical segment. Limb I with IDL seta 1 claw-like ( Fig. 15F ). Seta e of endite 2 being 1.5–1.7 times longer than seta f.

Male unknown.

Differential diagnosis: B. martensi differs from all species of the genus in shorter spine on basal segment of antennal exopodite. It has postabdomen evenly narrowing distally, this feature is shared only by B. elliptica .

Distribution and ecology. South Africa, the East Escarpment region of the Drakensberg mountains. All localities in a single quadrant between 28° and 29° S, 28° and 29° E, at altitudes between 1950 and 2400 m.a.s.l.. The species inhabits small, possibly temporary water bodies, mountain lakes, pools and tarns. The species was sampled at water temperature from 17º to 24º C, and pH from 5.8 to 8.2.

Figures

FIGURE 1. Biapertura affinis (Leydig, 1860) from Glubokoe Lake, Moscow Area, Russia.A–K, adult parthenogenetic female. A, lateral view. B–C, posteroventral angle of valves. D, head shield. E, head pores. F, labrum. G, postabdomen. H, postanal margin of postabdomen. I, postabdominal claw. J, antennule. K, antenna. L, ephippial female. M–O, adult male. M, lateral view. N, postabdomen. O, postabdominal claw. (A–L, orig.; M–O, after Sinev et al. 2020)

FIGURE 2. Biapertura affinis (Leydig, 1860) from Glubokoe Lake, Moscow Area, Russia. A–B, lateral view. C, dorsolateral view. D, dorsal view. E, ventral view. F, frontal view. G, ventral part of valve. H, postabdomen. I, postabdominal claw. J, antenna.

FIGURE 3. Biapertura affinis (Leydig, 1860) from Glubokoe Lake, Moscow Area, Russia, parthenogenetic female.A–B, head pores. C–E, posterior dorsal pores.

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 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).