Nedorhynchotalona chiangi Kotov & Sinev, 2011

Sinev, Artem Y., Liu, Ping & Han, Bo-Ping, 2024, New data on two rare East Asian cladocerans, Coronatella trachystriata (Chen, Zhang & Liu, 1994) and Nedorhynchotalona chiangi Kotov & Sinev, 2011 (Cladocera: Anomopoda: Chydoridae), Zootaxa 5523 (5), pp. 543-552 : 547-549

Nedorhynchotalona chiangi Kotov & Sinev, 2011

( Fig. 3–4 )

Chiang & Du 1979: 231, Figs. 159A–B ( Rhynchotalona falcata ); Kotov & Sinev, 2011: 281–283, Figs. 5–6; Kotov et al., 2012: 83–84, Figs. 26–27; Ji et al., 2015: 261; Rogers et al., 2019: 693, Figs. 16.2.29 A–B; Korovchinsky et al. 2021: 367, Figs. 111, 1–6.

Type locality. River Amur near the mouth of Zeya River in the region of Blagoveshchensk town, Amur Area, Russia .

Material studied: 2 parthenogenetic females from Qili lake , Jiangsu Province, China, 32.9076° N, 118.2356° E, 31.03.2024 .

Features revealed by SEM examination. Body ( Figs. 3A–C ) low oval in lateral view.

Valves covered by sculpture as over 20 thick, rarely anastomosing longitudinal lines, distance between lines 2–3 times greater than line thickness, space between lines without any microsculpture. Anteroventral portion of valve ( Fig. 3D ) with several diagonal wrinkles of same thickness. Posteroventral angle of valve ( Fig. 3E ) armed with about 70 thin setulae, not organized into the groups, continues into a row of about 200 setulae along posterior margin on inner side of valve. These setulae are more or less uniform in ventral part of valve, but strongly differentiated in dorsal half of valve.

Head shield ( Fig. 3C ) without any sculpture, with strongly curved rostrum, in lateral view rostum narrow, in frontal view rostrum ( Figs. 3C, F , 4A ) evenly narrowing to the apex, apex of rostrum blunt. Frontal pore absent, in other Aloninae this structure is located between bases of antennulae ( Fig. 3F ). Posterior part of head shield ( Fig. 3G ) of typical shape of Aloninae , posterior margin of rostrum broadly rounded. Major head pores absent, lateral head pores minute, located at distance about 15–20 µm from midline.

Postabdomen ( Fig. 4B ) with a very broadly rounded distal angle, narrowing in distal half of postanal portion. Ventral margin almost straight. No incursion between distal margin and basis of claws. Distal margin weakly convex. Dorsal margin weakly convex in postanal portion and unevenly concave in anal one, distal part 1.5 times longer than preanal one, postanal portion 1.3 times shorter than anal one. Preanal angle well-defined, strongly prominent, postanal angle not defined. Preanal margin almost straight. Three clusters of short setulae located near ventral margin. Postanal margin ( Fig. 4C ) with 6–7 groups of 2–5 very short marginal denticles, length of distal denticles is two times less than width of postbdominal claw base. Postanal lateral clusters of setulae consisting of 4–8 rather thick setulae each, number of setulae decreases posteriorly. Distal setula in each cluster longer and thicker than others, its length slightly greater than width of postabdominal claw base. Postabdominal claw ( Fig. 4D ) slender, long, unevenly curved. Outer margin with pecten of numerous very short thin setulae. Basal spine slender, clearly curved, its length about 0.15 length of claw.

Antennule ( Fig. 3F ) short, distance from end of antenna to the end of rostrum is greater than the antennal length. Antennular seta long, reaching to lateral margin of rostrum, aesthetascs short, not reaching outside of the rostrum.

Antenna short ( Fig. 4E ).Antennal formula, setae 0–0–3/0–1–3, spines 1–0–1/0–0–1. Basipodite robust, branches short and stout. Basal segments of both branches twice longer than middle and apical segments. Basal segment of endopodite without a seta. Seta arising from middle segment of endopod as long as shortest apical setae. Both apical segments with three setae of similar thickness. Spine on basal segment of exopod extremely long, longer than middle and apical segment. Spines from apical segments very long, 1.5 times longer than apical segments. Middle segments of exopodite with clusters of long thick setulae.

Thoracic limb examination ( Fig. 4F–G ) confirms diagnostic features of the species, including presence of an accessory seta on limb I, inner distal lobe setae of limb I armed with long setulae distally, scraper 6 of limb II being shorter and more robust than neighbours, and armed with thick spines, first flaming-torch seta of endite of limb IV being larger than two others and armed with thicker longer setulae.

Figures

FIGURE 3. Nedorhynchotalona chiangi Kotov & Sinev, 2011 from Qili lake, Jiangsu Province, China, parthenogenetic female. A, lateral viev. B, ventrolateral viev. C, frontolateral view. D, posteroventral portion of valves. E, posterior margin of valve from inner side. F, rostrum and antennules. G, head pores, position of lateral pores indicated by arrows.

FIGURE 4. Nedorhynchotalona chiangi Kotov & Sinev, 2011 from Qili lake, Jiangsu Province, China, parthenogenetic female. A, head in ventral view. B, postabdomen. C, dorsal margin of postabdomen. D, postabdominal claw. E, antenna. F–G, thoracic limbs, abbreviations: e2–e3—endites 2–3 of limb I, endIII—distal endite of limb III, endIV—endite of limb IV, exII—exopodite of limb II, IDL—inner distal lobe of limb I, ODL—outer distal lobe of limb I, lab—labrum, 2–8—respective scraping setae of limb II.