Prendalona guttata ( Sars, 1862 ) 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 : 107-112

Prendalona guttata ( Sars, 1862) comb. nov.

Figs. 7–10 .

Sars, 1862: 286–287 ( Alona ); Lilljeborg, 1901: Pl. 68: Fig. 16–19, 23, 24 ( Lynceus guttatus ); Smirnov, 1971: 379–382, Fig. 450, 454, 456 ( Alona ); Fl̂ssner, 1972: 296–299, Pl. 139 ( Alona ); Chiang, Du, 1979: 225–226, Fig. 154A–F ( Alona ); Negrea, 1983: 293–255, Fig. 119A–D ( Alona ); Alonso, 1996: 329– 331, Fig. 146 ( Alona ); Fl̂ssner, 2000: 313–315, Pl. 116 ( Alona ); Sinev, 1999: 29–30, Fig. 5 ( Alona ); Sinev, 2002: 934–935, Fig. 2 г, З, л, о, т ( Alona ); Hudec, 2010: 324–327, Fig. 79 ( Alona ); Kotov et al., 2010 ( Alona ): 247, Fig 138, 4, Fig 143, 1–3 ( Alona ); Sinev & Silva-Briano, 2012: 15–19, Fig. 8–9 , 10 A–J ( Alona ); Korovchinsky et al. 2021: 286–288, Fig. 85, 1–9 ( Alona ).

Type locality: Østensjøvannet lake , Oslo, Norway .

Type material: non-existent, no material from type locality is present in G.O. Sars collection, deposited at Zoological Museum of Oslo University ,

Material examined. Norway: 20 parthenogenetic females from G.O. Sars collection, labeled just as “Norway”, Zoological Museum of Oslo University, sample F12411а; over 20 parthenogenetic females, 12 ephippial females, 8 adult males from Sagtjenn pond, Risør town , Agder county , coll. by J.–P. Nielssen . Russia: over 50 parthenogenetic females from littoral zone and coastal Sphagnum moss at Krugloe Lake (66.5426° N, 33.1393° E) in the vicinity of White Sea Biological Station of M. V. Lomonosov Moscow State University, Chupa District , Republic of Karelia, 07–08.2021, coll. A. Y. Sinev & I.A. Dadykin; 4 parthenogenetic females, 1 male from lake near Kur’ya Strelka, Yakutia Autonomous Republic (62.01857° N, 129.757° E) 09.2011 coll. E.I. Bekker, A.I. Klimovsky, AAK M-2290 ; China: 3 parthenogenic females from Liangzi lake, Hunan Prowince , (30.23894° N, 114.45440° E) 29.10.2018, coll. A. Y. Sinev & Y. Gu.

Material examined previously. See Sinev (1999; 2002) for the list of material from Russia. Sinev & Silva-Briano (2012) for the list of material from Mexico. Morphology of parthenogenetic females of P. guttata , examined earlier during faunistic studies of Zeya River basin in the Amur Area of Russia ( Kotov et al. 2011). Jeju-do Island in South Korea ( Kotov et al. 2022). Yunnan Province ( Sinev et al. 2020) and Hainan Island ( Sinev et al. 2015) in China. All of this material not differ from that of examined specimens.

Description. Parthenogenetic female. General. In lateral view body ( Figs. 7A , 8A–E ) oval of moderate height, maximum height at middle of body; in adults height/length ratio 0.65–0.70. Dorsal margin uniformly curved; postero-dorsal and postero-ventral angles broadly rounded; posterior margin uniformly curved; ventral margin almost straight; antero-ventral angle rounded. Body moderately compressed laterally.

Valves with a weakly developed linear sculpture in posteroventral portion ( Figs. 8A–D ), or fully covered with tubercules ( Figs. 8E–F ). Ventral margin with about 35–40 setae, anterior ten setae short, not forming separate group from central setae, distal setae of moderate length ( Fig. 7B ). Posterodorsal angle ( Fig. 7C ) bears about 70 short, thin, hair-like setulae of similar length, not organized in groups. A row of about 80 thin setulae along the posterior margin on inner side of valve.

Head of moderate size, triangle-round in lateral view, rostrum short, pointing downward. Compound eye larger than ocellus. Distance from tip of rostrum to ocellus in adults slightly greater than that between ocellus and eye. Head shield with a maximum width behind mandibular articulation, oblique in specimens with linear sculpture of valves, tuberculate in specimens with tuberculate valves; rostrum short, broadly rounded; posterior margin of head shield broadly rounded. Three connected major head pores ( Figs. 7D – 9B ), median pore located in the middle between two others and smaller than them, PP less than 0.5 IP. Lateral head pores minute, located about 1.0–1.2 IP distance from midline, at the level between anterior and middle major head pores.

Labrum ( Fig. 7E ) of moderate size; labral keel narrow (height about 2 width), with a rounded apex; anterior margin of keel convex, irregular in some specimens ( Fig. 7E ), posterior margin with two clusters of short setulae. In some specimens, posterior portion of labrum overgrown with epibiotic bacteria.

Thorax twice longer than abdomen, dorsal surface of abdominal segments not saddle-shaped.

Postabdomen ( Figs. 7G–H , 9C ) short, of moderate width, narrowing distally, with a prominent acute distal angle, length about 2.5 height. Ventral margin straight. Base of claws separated from distal margin by a clear incision. Distal margin straight to weakly convex, distal angle prominent, protruding before the base of claw, acute with rounded tip. Dorsal margin with distal part 1.6–1.7 times longer than preanal one, with anal and postanal portions of similar length. Postanal portion of distal margin straight, anal portion concave. Preanal angle well-defined, strongly protruding, postanal angle weakly defined. Postabdomen with 5–6 well-developed narrow postanal marginal denticles, decreasing in size basally and with three–four groups of marginal setulae on anal margin. Most denticles with 1–6 spinules anteriorly; length of distal denticles exceed width of the postabdominal claw base. Eight–nine lateral groups of setulae, five–seven distalmost groups wide, with longest setulae in the middle, of similar length with longest marginal denticles. Several additional groups of short setae near preanal angle. Postabdominal claw of a moderate length, slightly shorter than preanal portion of postabdomen. Basal spine about 0.2 of length of claw.

Antennule ( Fig. 7I ) of moderate size, length about 2.5 width, with three clusters of long thin setulae at anterior face. Antennular sensory seta slender, two times shorter than antennule, arising almost at the middle of antennule. Nine terminal aesthetascs, two longest of them about 2/3 length of antennule.

Antenna ( Figs. 7J , 9A–D ) relatively short. Antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0–0–1. Basipodite robust, branches of moderate length and width, proximal segments of both branches 1.5 times longer than others. Seta arising from proximal segment of endopodite thin, not reaching the end of endopodite. Seta arising from middle segment of endopodite of similar size with shortest apical setae; in both branches one apical setae is much shorter than two others. Spine on proximal segment of exopodite significantly shorter than middle segment. Apical spines slightly longer than apical segments.

Maxillule ( Fig. 10A ) very small, with two setae, setulated in distal portion.

Thoracic limbs: Six pairs.

Limb I ( Figs. 10B–D ) as in the previous species. but endite 1 without seta i.

Limb II ( Figs. 10E– F ). Similar to that of previous species, but scraping seta 3 only slightly thicker than setae 2 and 4, with small spinules.

Limb III ( Figs. 10G–J ). Epipodite oval, without process; exopodite trapezoid with seven setae. Seta 3 being longest, seta 6 of about 3/4 length of seta 3, setae 4 and 7 of about 1/2 length of seta 3, other setae short. Setae 6–7 with short setulae in distal portion, all other setae plumose. Inner portion as in the previous species.

Limb IV ( Figs. 10K–L ). Preepipodite setulated, epipodite with process longer than exopodite itself. Exopodite rounded, with six setae. Seta 3 longest, setae 1, 2 and 5 slightly shorter than seta 3, setae 4 and 6 of 1/3 and 1/2 length of seta 3, respectively. Setae 1–4 plumose, setae 5–6 appear naked under the light microscope. Inner-distal portion of limb IV same as in the previous species.

Limb V ( Fig. 10M ). As in the previous species.

Limb VI ( Fig. 10N ) as in the previous species.

Male. General. Body low oval, with maximum height at the middle, height/length ratio about 0.6.

Head. Compound eye larger than ocellus.

Postabdomen ( Figs. 7M–N ) short, moderately wide, evenly narrowing distally. Postanal margin of postabdomen evenly comes to the base of claws, no distinct distal margin and dorsodistal angle. Length about 2.5 height. Ventral margin straight or weakly convex. The sperm ducts open at the end of postabdomen, forming minute protrusion above the base of claws. Dorsal margin almost straight in postanal portion and clearly concave in anal one. Preanal and postanal angles not defined. Preanal margin weakly convex to straight. Distal portion of postabdomen 2.5 times longer than preanal one, anal and postanal portions of similar length. Postanal margin with clusters of setulae, in distalmost 4–5 clusters distalmost setula thick, spine-like ( Fig. 9N ). Lateral groups of setulae as in female. Postabdominal claw ( Figs. 7M–N ) weakly curved, shorter than in female, much shorter than preanal margin of postabdomen, with acute tip without cluster of setulae. Basal spine very short, with short spinule near it.

Antennule ( Fig. 7O ) slightly broader than in female, with 12 long terminal aesthetascs, longest aesthetascs about 2/3 length of antennule. Male seta located at 2/3 distance from the base, not reaching the end of antennule.

Thoracic limb I ( Fig. 10 O ) same as in the previous species,

Size. Adult female length 0.3–0.39 mm, height 0.19–0.25 mm. Adult male length 0.25–0.28 mm, height 0.14– 0.17 mm.

Differential diagnosis. P. guttata differs from P. arvensis in; (1) three main head pores and (2) labral keel without a prominence on anterior margin; from P. werestschagini in: (1) a smaller size, (2) smaller IP/PP ratio, and (3) shape of both male and female postabdomen. P. guttata is habitually similar to P. barbulata but differs in: (1) head shield with broadly rounded posterior portion, (2) female postabdomen with acute prominent distal angle and strongly prominent preanal angle, (3) absence of seta i on endite 1 of thoracic limb I, and (4) evenly narrowing distally male postabdomen. P. guttata differs from P. julietae sp. nov. in: (1) shorter spine near basal spine on postabdominal claw of male and (2) proportion of male seta on the first limb.

Distribution and ecology. The taxon is recorded worldwide, but probably it is represented by a complex of cryptic species. P. guttata s. str. is distributed in Palearctic. Taxonomic status of P. cf. guttata from Nearctic, Afrotropic, Indo-Malaysian and Australian regions is unclear. Records of P. guttata from the Neotropics probably all belong to P. julietae sp. nov. P. guttata s. str. in Palearctic is eurybiotic, eurythermic species, usually associated with shore vegetation, inhabiting littoral zone of lakes and ponds, floodplain water bodies, slow rivers, swamps and bogs, temporary water bodies, and also encountered in subterranean water. Encountered at pH> 3.8, at altitudes up to 5520 m a.s.l. ( Korovchinsky et al. 2021). For detailed data on ecology see Duigan (1992) and Fryer (1993).

Figures

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 5. Prendalona barbulata (Megard, 1967) from Salmon lake, Missoula county, Montana, USA. Parthenogenetic female. A, postabdomen. B–C, postanal margin of postabdomen. Juvenile male of instar II. D, postabdomen. Adult male. E–F, postabdomen.

FIGURE 7. Prendalona guttata (Sars, 1862) from Sagtjenn pond, Risør town, Agder county, Norway. Parthenogenetic female. A, lateral view. B, ventral margin of valves. C, posteroventral angle of valves. D, head pores. E–F, labrum. G–H, postabdomen. I, antennule. J, antenna. Ephippial female. K, lateral view. Adult male. L, lateral view. M–N, postabdomen. O. antennule.

FIGURE 8. Prendalona guttata (Sars, 1862). Parthenogenetic female from from Sagtjenn pond, Risør town, Agder county, Norway. A–B, lateral view. C, frontolateral view. D, dorsolateral view. Parthenogenetic female from Krugloe Lake, Chupa District, Republic of Karelia, Russia, E–F, lateral view.

FIGURE 9. Prendalona guttata (Sars, 1862). Parthenogenetic female from Sagtjenn pond, Risør town, Agder county, Norway. A, antenna. Parthenogenetic female from Krugloe Lake, Chupa District, Republic of Karelia, Russia, B, head pores. C, postabdomen. D, antenna.

FIGURE 10. Prendalona guttata (Sars, 1862) from Sagtjenn pond, Risør town, Agder county, Norway. Maxillae and thoracic limbs. Parthenogenetic female. A, maxillule. B, limb I (setae a, b, d not shown). C, setae a, b, d of limb I. D. ODL and IDL of limb I. E, limb II. F, exopodite of limb II. G, exopodite of limb III. H–J, structures of inner portion of limb III. K, exopodite of limb IV. L, inner portion of limb IV. M, limb V. N, limb VI. Adult male. O, limb I.