Coronatella (Coronatella) trachystriata ( Chen, Zhang &Liu, 1994 )

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 : 544-547

Coronatella (Coronatella) trachystriata ( Chen, Zhang &Liu, 1994)

( Figs. 1 A–F , 2 )

Chen et al., 1994: 101–102, Figs. 1–3 ( Alona rectangula var. trachystriata ); Kotov et al., 2011: 138–141, Fig. 6 ( cf. trachystriata ); Ji et al., 2015: 258; Sinev et al., 2015: 577, Figs. 1D–K ; Sinev, 2016: 467, Figs. 9 I–L; Rogers et al., 2019: 698, Figs. 16.2.32 I–L, Korovchinsky et al. 2021: 315–316, Figs. 93, 11–17.

Type locality. Pond in Guixi district, Jiangxi Province, China .

Material studied: four specimens from Qili lake , Jiangsu Province, China, 32.9076° N, 118.2356° E, 31.03.2024 .

Features revealed by SEM examination. Body ( Fig. 1A–D ) oval in lateral view, in all specimens valves were significantly deformed during critical-point drying, suggesting that valve cuticle is delicate. In contrast, specimens of C. (C.) rectangula ( Fig. 1G–H ), from the same sample and dried together with the studied specimens, were not deformed.

Valves are covered by peculiar sculpturing of densely spaced longitudinal ridges and lines ( Fig. 2A–B ). The ridges are present in dorsal two-third of valves, but are interrupted in the small area of the egg locule. Each valve bears about 20 ridges, distance between ridges is about 5 µm, ridge width about 1.5 µm, height of ridge variable, in most expressed ridges it exceeds ridge width. Space between ridges without any microsculpture. Ventral third of valve with 5–7 longitudinal lines of appearance typical of other Coronatella species in posterior portion, area near anteroventral angle without any sculpture.

Head shield without any sculpture, with elongated rostrum ( Fig. 2C–D, F ). Ventral margin of rostrum straight in frontal view. Posterior portion of head shield broadly rounded. Three major head pores ( Fig. 1E ) with a narrow connection between them, distance between posterior pore and posterior margin of head shield (PP) about 1/3 distance between anterior and posterior pore (IP). Lateral head pores minute, located at level of middle major head pore at distance about 0.8 IP.

Postabdomen ( Fig. 1F ) with a broadly rounded distal angle, clearly narrowing in distal half of postanal portion. Three clusters of short setulae located near ventral margin. Postanal margin with 2–3 short narrow marginal denticles, length of distal denticles 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 c.a. 2.5 widths of postabdominal claw base. Postabdominal claw slender, long, unevenly curved. Outer margin with pecten of numerous very short thin setulae. Inner margin with setulae divided into two groups, basal group with about 30 short thin setulae of similar length, distal group with about 20 longer and thicker setulae, decreasing in size distally. Basal spine slender, clearly curved, its length about 0.2 length of claw.

Antennule ( Fig. 2D ) short, distance from its end to the end of rostrum equal to antennule length, aesthetascs short, not projecting outside of rostrum.

Antenna short ( Fig. 2C, E–F ). 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 1.5 times longer than middle and apical segments. Basal segment of endopodite without a seta (see Fig. 2C ). Seta arising from middle segment of endopod shorter than apical setae. Both apical segments with three setae of similar thickness. Spine on basal segment of exopod extremely long, 1.5 times longer than middle segment. Spines from apical segments extremely long, 1.5 times longer than apical segments. Basal and middle segments of exopodite with clusters of long thick setulae.

Figures

FIGURE 1. Coronatella (Coronatella) trachystriata (Chen, Zhang & Liu, 1994) from Qili lake, Jiangsu Province, China, parthenogenetic female. A–B, lateral view. C, frontolateral view. D, dorsolateral view. E, head pores. F, distal portion of postabdomen. Coronatella (Coronatella) rectangula (Sars, 1861) from Qili lake, Jiangsu province, China, parthenogenetic female. G, lateral view. H, frontolateral view.

FIGURE 2. Coronatella (Coronatella) trachystriata (Chen, Zhang & Liu, 1994) from Qili lake, Jiangsu Province, China, parthenogenetic female. A, dorsal part of valves in lateral view. B, dorsal part of valves in dorsal view. C, head. D, rostrum and antennule. E–F, antenna.

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.