Prendalona werestshagini ( Sinev, 1999 ) Sinev & Sousa & Elmoor-Loureiro, 2023

Sinev, Artem Y., Sousa, Francisco Diogo Rocha & Elmoor-Loureiro, Lourdes M. A., 2023, Revision of the guttata-group of Alona s. lato leads to its translocation to Prendalona Sousa, Elmoor-Loureiro & Santos, 2018 (Cladocera: Anomopoda: Chydoridae), Zootaxa 5293 (1), pp. 95-121 : 115-117

Prendalona werestshagini ( Sinev, 1999) comb. nov.

( Fig. 13 )

Smirnov, 1971: 380, Fig. 451 ( Alona guttata guttata partum); Chiang, 1963: Plate VI: Fig. 39–40 ( Alonella rostrata ); Chiang, Du, 1979: 227, Fig. 155A–D ( Alona pulchella ); Sinev, 1999: 23–30, Fig. 1–4 ( Alona ); Sinev, 2002: 938, Fig. 1 л, 3и,с, 4и, 5д,л ( Alona ); Sarmaja-Karjonen & Sinev, 2008: 44–46, Fig. 2A–F ( Alona ); Kotov et al., 2010: 247, Fig. 141: 12–14 ( Alona ); Korovchinsky et al., 2021: 288–289, Fig. 85: 10–14 ( Alona ); Sinev et al. 2021: 243–248, Fig. 1–4 ( Alona ).

Type locality. Lake in Ara-Bel’ river valley, 40 km from Petrov’s glacier, Central Tien-Shan, Kyrgyzstan.

Type material. Holotype. Adult male, at Zoological Museum of M. V. Lomonosov Moscow State University, Ml –08.

Paratypes. Over 30 parthenogenetic and ephippial females, 5 adult males, 2 juvenile males of instar II at Zoological Museum of M. V. Lomonosov Moscow State University , Ml –09 – Ml –14 .

Material studied earlier: see Sinev (1999, 2002) and Sinev et al. (2021) for the list of material from Russia, Kyrgyzstan and Mongolia.

Description. Parthenogenetic female. General. Body ( Fig. 13A ) oval in lateral view, strongly compressed laterally, of moderate height, maximum height at middle of the body; in adults height/length ratio 0.67–0.70. Dorsal margin uniformly curved; posterodorsal and posteroventral angles broadly rounded; posterior margin uniformly curved; ventral margin almost straight; anteroventral angle rounded.

Valves with weak longitudinal lines. Ventral margin with 40–50 setae. Posterodorsal angle with about 70 setulae.

Head. Compound eye and ocellus large, of similar size. Head shield ( Fig. 13B ) without sculpturing, with a broadly rounded posterior portion. Three major head pores, median pore located in the middle between the other two, PP about 0.7–1.1 IP ( Fig. 13C ). Lateral head pores located at about 0.8 IP distance from midline, at the level of middle major head pore.

Labrum. Labral keel without prominence at anterior margin, posterior margin of keel with two clusters of setulae.

Postabdomen ( Fig. 13D ) short, of moderate width, slightly narrowing distally, with a rounded, slightly prominent distal angle; length about 2.5 height. Ventral margin straight. Distal margin weakly convex to straight. Dorsal margin with distal part 1.6–1.8 times longer than preanal one, with postanal portion equal to or slightly shorter than anal. Postanal portion of dorsal margin straight, anal portion weakly concave. Postanal and distal part of anal margin with 8–10 well-developed composite marginal denticles, decreasing in size basally, most bearing spinules on anterior margin; length of distal denticles equal to the width of the postabdominal claw base. Postanal margin with 9–12 lateral groups of setulae, six–seven distalmost groups wide, consisting of thin setulae, with longest setulae in the middle, slightly shorter than longest marginal denticles. Several additional groups above the main row in anal portion. Postabdominal claw curved, of moderate length, slightly longer than preanal portion of postabdomen. Basal spine short, almost straight, about 0.2 of claw length.

Morphology of antennule and antenna typical for the genus. Morphology of thoracic limbs typical for the genus. Thoracic limb I with rudimentary seta i on endite 1. Thoracic limb III with seta 4 longer than seta 5, almost as long as seta 6.

Ephippial female ( Fig. 13E ). General. Body slightly higher than in parthenogenetic female, with defined posterodorsal angle and almost straight posterior margin of valves. Ephippium intensive yellow-brown in preserved specimens, with well-developed sculpture in shape of thick longitudinal, sometimes anastomosing lines, much thicker than those on the rest of valves.

Male. General. Body low oval to ovoid ( Fig. 13F ), with a maximum height at middle, height/length ratio about 0.6.

Postabdomen ( Fig. 13G ) elongated, strongly narrowing distally in anal portion; in postanal portion narrow, with almost parallel margins. Postanal margin of postabdomen evenly comes to the base of claws, dorsodistal and dorsoventral angles obtuse. Length about three heights. Ventral margin weakly convex to straight. Sperm duct opens at the end of postabdomen under the base of claws. Dorsal margin weakly concave to straight in postanal portion and weakly convex in anal one. Preanal and postanal angles not defined. Preanal margin convex. Distal portion of postabdomen 2.5 times longer than preanal one, postanal portion 1.5 times longer than anal. Postanal margin with 7–8 clusters of strong spinules in distal portion. Distal half of postanal portion with clusters of thick, sharp spinules laterally; posterior half of postanal portion and anal portion with about 10 groups of lateral setulae in a row, similar in morphology to those of female, but somewhat thicker. Postabdominal claw short, curved, 1.5 times shorter than preanal margin of postabdomen. Basal spine absent.

Antennule with male seta located at 2/3 distance from the base, its length slightly less than half-length of antennule.

Thoracic limb I typical of the genus, endite 1 with rudimentary seta i.

Size. Adult female length 0.42–0.54 mm, height 0.29–0.36 mm. Adult male length 0.32–0.38 mm, height 0.2– 0.24 mm.

For full description see Sinev (1999) and Sinev et al. (2021).

Differential diagnosis. Prendalona werestschagini differs from all other species of the genus in: (1) a greater size (up to 0.55 mm), and (2) greater IP/PP ratio, about 1. P. werestachagini clearly differs from P. guttata , P. juiletae sp. nov. and P. barbulata in long and narrow male postabdomen, armed with strong spinules, and from P. arvensis in three major head pores and in in labral keel without prominence on anterior margin.

Distribution and ecology. Eurasian species with an Arcto-Alpine distribution. Recorded from: Iceland; Svarbald Islands; north of Scandinavia; Russia (North Karelia, Kola Peninsula, Komi Republic, Wrangel island, Chukotka Autonomous Republic, north Kamchatka Peninsula, Bering island, Altai mountains, Sayan mountains); Kyrgyzstan (Tien Shan mountains); China (Tibet plateau); India (Himalaya); and mountains of West Mongolia. Species is predominantly found in cold oligotrophic lakes, and in small floodplain water bodies ( Sinev et al. 2021).

Figures

FIGURE 1. Prendalona arvensis (Sousa, Elmoor-Loureiro & Santos, 2016), parthenogenetic female.A, lateral view. B–C, anterior and posterior parts of ventral margin of valve. D, posterior portion of head shield in lateral view. E, labrum. F, postabdomen. G, thoracic limb I. H, ODL and IDL of thoracic limb I (after Sousa et al. 2016a).

FIGURE 2. Prendalona barbulata (Megard, 1967) from Salmon lake, Missoula county, Montana, USA. Parthenogenetic female. A, lateral view. B–C, setae of anterior and posterior parts of ventral margin of valves. D, posteroventral angle of valves. E, head shield. F, head pores. G–H, labrum. I, antennule. J, antenna. Ephippial female. K, lateral view. Juvenile male of instar II. L, lateral view. M, antennule. Adult male. N, lateral view. O, labrum. P. antennule.

FIGURE 3. Prendalona barbulata (Megard, 1967) from Salmon lake, Missoula county, Montana, USA, Parthenogenetic female.A, lateral view. B, frontolateral view. C, dorsolateral view. Ephippial female. D–E, lateral view.Adult male. F, lateral view. G, dorsolateral view.

FIGURE 4. Prendalona barbulata (Megard, 1967) from Salmon lake, Missoula county, Montana, USA. Ephippial female. A, labrum and thoracic limb I. B, posterior portion of labrum, covered by bacteria. C, head pores. D, postabdomen. E, antenna. Adult male. F, postabdomen.

FIGURE 13. Prendalona werestschagini (Sinev, 1999) Parthenogenetic female. A, lateral view. B, head shield. C, head pores. D, postabdomen. Ephippial female. E, lateral view. Adult male. F, lateral view. G, postabdomen. (after Sinev et al. 2021).