Prendalona Sousa, Elmoor-Loureiro & Santos, 2018

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 : 97-98

Genus Prendalona Sousa, Elmoor-Loureiro & Santos, 2018 emend. nov.

Sousa, Elmoor-Loureiro & Santos, 2016a: 28–34 ( Prenda ); Sousa, Elmoor-Loureiro & Santos, 2018: 1–2.

Type species: Prenda arvensis Sousa, Elmoor-Loureiro & Santos, 2016

Emended diagnosis. Parthenogenetic female. General. Small to medium-sized alonines, length of adult female up to 0.55. Body of the Alona -like habitus, of moderate height, moderately compressed laterally. Head and carapace without a dorsal keel.

Valves. Ventral margins of valves in ventral view almost straight, valves can be closed without even a narrow gap between them. Dorsal margin of carapace convex, postero-dorsal and postero-ventral angles broadly rounded. Posterior margin weakly convex. Antero-ventral angle rounded. Ventral margin weakly convex to straight, with 30– 50 setae, anterior setae short, not forming separate group from central setae, posterior setae of moderate length, decreasing in length posteriorly. Posteroventral angle without denticles, with numerous thin setulae of similar length, not forming groups. Carapace ornamentation as weakly to well-developed longitudinal lines or as tubercules.

Head relatively small, low, triangular-rounded in lateral view. In lateral view rostrum relatively narrow, protruding downwards. Ocellus and compound eye present. Head shield with a maximum width behind mandibular articulation. Rostrum short and rounded. Posterior part of head shield broadly rounded or triangular with defined tip. Three or two major head pores with a narrow connection between them. PP about 1 IP or less in adults. Lateral head pores minute.

Labrum of moderate size. Labral keel moderately wide, with a rounded apex. Anterior margin of keel convex or with blunt prominence in upper portion, posterior margin with two clusters of short setulae.

Thorax two times longer than abdomen. Dorsal surface of abdominal segments not saddle-shaped. Abdominal joint not developed.

Postabdomen of moderate size, moderately high, length about 2.5 height. Basis of claws bordered from distal margin by a clear incision. Distal margin from straight to convex; distal angle obtuse, straight, or acute, prominent. Dorsal margin almost straight in postanal portion and concave in anal one, with distal part about 2 times longer than preanal one, with postanal and anal portion 2.5 of similar length. Preanal angle well-expressed, postanal angle weak to not defined. Preanal margin almost convex. Postanal margin with 5–8 well-developed, sharp composite denticles, most with spinules along anterior margin; size of denticles increasing distally. Length of longest denticles equal to the width of base of postabdominal claw. About 8–10 lateral groups of setulae in the main row, distalmost 5–8 groups with all setulae of similar thickness, in most species central setulae in the group being longest. Postabdominal claw of moderate length, similar in length to preanal portion of postabdomen. Basal spine short, about 0.15–0.2 length of the claw.

Antennule of moderate size, length about 2.5–3 widths, with 3–4 clusters of setulae at anterior face. Antennular seta thin, about 1/3–1/2 length of antennule, arising at 1/3–1/2 distance from the end of antenna. Nine terminal aesthetascs of similar length, about 1/2–2/3 length of antennule.

Antenna re latively short. Antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0–0–1. Basipodite robust, with very short seta between branches, branches relatively short. Proximal segments in both branches 1.5 times longer than two others. Seta arising from basal segment of endopodite thin, much shorter than other setae. Antennal spines well-developed, spine on basal segment of exopodite of same length or slightly shorter than middle segment, apical spines as long as apical segments.

Thoracic limbs: six pairs.

Limb I of moderate size. Accessory seta two times shorter than ODL seta. IDL with three setae, seta 1 very short, setae 2 and 3 long, with thin setulae in distal part. Endite 3 with four setae subequal in length. Endite 2 with two long distally setulated setae (e–f), a shorter seta near their base (d), without inner seta. Endite 1 with two 2-segmented setae, both setulated in distal part, with seta i rudimentary or absent, without inner seta.

Limb II. Exopodite elongated, with a slender seta. Eight scraping spines, three basalmost spines (6–8) subequal in length, others increasing in length distally. Distal armature of gnathobase with four elements. Filter plate II with seven setae, the posteriormost member shorter than others.

Limb III. Exopodite with seven setae. Seta 3 being longest, seta 6 second in length. Setae 1–5 plumose, setae 6–7 with short setulae in distal part. Morphology of inner portion typical of subfamily; scraping setae of distal endite moderately long. Filter plate III with seven setae.

Limb IV. Exopodite with six setae. Setae 1–4 flat, plumose, setae 5–6 with short setulae. Inner portion of limb IV with four setae and a small sensillum. Scraping seta slender, distalmost flaming-torch seta (2) large, with broad base and robust setulae, two other two times narrower, armed with very thin, hair-like setulae. Three soft setae slightly increasing in size basally. Gnathobase with 2-segmented seta and a small hillock. Filter plate IV with five setae.

Limb V. Exopodite divided into two lobes, with four plumose setae, setae 1–3 long, subequal in length; seta 4 shorter. Inner lobe narrow oval, with a setulated inner margin. At inner face, two setae densely setulated in distal part, one of them long; length similar to that of exopodite setae 1–3. Filter plate V with three setae.

Limb VI as an oval lobe with setulated margin, as large as exopodite V.

Male. General. Body low oval, with a maximum height at the middle or behind it.

Postabdomen of variable shape, sperm ducts open on distal margin. Preanal and postanal angles not defined. Clusters of thin or robust setulae in place of female marginal denticles on postanal margin. Postabdominal claw much shorter than in female, basal spine very short or absent.

Antennule broader than in female, with 12 terminal aesthetascs, male seta located laterally. Thoracic limb I with a copulatory hook of moderate size, half as long as limb itself. IDL without seta 1, IDL setae 2 and 3 much thinner and shorter than in female; male seta curved, long.

Differential diagnosis: Prendalona clearly differs from its sister-group, genus Flavalona in: (1) minute lateral head pores without any pockets below, (2) absence of a genital process on male postabdomen and (3) absence of inner setae on endites 1–2 of thoracic limb I. From all other genera of Alona s. lato, Prendalona differs in: (1) differentiated flaming-torch setae of limb IV and (2) weakly-developed lateral fascicles of postabdominal setulae, with distalmost setula not being much thicker than the others. As a member of the Hexalona branch, Prendalona clearly differs from genera of the Coronatella branch, Coronatella , Anthalona , Karualona, Magnospina in: (1) presence of limb IV and (2) seven setae on exopodite III. Prendalona differs from Alona s. str. (the quadrangularis -group) and Ovalona in: (1) weakly developed IDL seta 1, (2) presence of a filter plate V and (3) presence of limb VI. It clearly differs from other groups of the Hexalona branch, such as Biapertura , Armatalona , and intermedia -groups in; (1) shape and armament of postabdomen, (2) absence of inner setae on endites 1–2 of thoracic limb I and (3) reduced or absent seta I on endite III of limb I. For summary of differences between the Hexalona genera see Table 1 .