Anthalona vandammei, Sinev & Tiang-Nga & Sanoamuang, 2023

Sinev, Artem Y., Tiang-Nga, Supatra & Sanoamuang, Laorsri, 2023, Anthalona vandammei sp. nov. from Thailand, a sibling species of Neotropical Anthalona brandorffi (Sinev & Holwedell, 2002) (Cladocera: Anomopoda: Chydoridae), Zootaxa 5230 (1), pp. 67-78 : 68-73

publication ID 10.11646/zootaxa.5230.1.4

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Anthalona vandammei

sp. nov.

Anthalona vandammei sp. nov.

Maiphae, Pholpunthin & Dumont 2008: 34, fig. 2b ( Alona verrucosa ).

Etymology. the species is named after our friend and colleague, prominent Belgian cladocerologist Kay Van Damme.

Type locality. Lake Kud-Thing , Bueng Kan province, Thailand, 18° 18.548’ N, 103° 39.700’ E. The type series was collected on 30.01.2017 by A.Y. Sinev & S. Tiang-nga. Samples were collected at a depth of about 0.5 m, where there were dense standing and submerged macrophytes GoogleMaps .

Holotype. A parthenogenetic female from the type locality, deposited in the Zoological Museum of M. V. Lomonosov Moscow State University , Ml-260.

Paratypes. Four parthenogenetic females from the type locality, deposited in the Zoological Museum of M. V. Lomonosov Moscow State University , Ml-261 .

Other material studied. Five specimens from the type locality were dissected for appendage analyses but not kept; three specimens were used for SEM studies.

Description. Parthenogenetic female. In lateral view, body high, egg-shaped ( Figs. 1A View FIGURE 1 , 2A–E View FIGURE2 ); maximum height after the middle of the body. Height-length ratio 0.65–0.7 in adults. Dorsal margin convex, posterodorsal and posteroventral angles broadly rounded. Posterior margin convex, ventral margin almost straight, anteroventral angle rounded. Ventral margin ( Fig. 1B View FIGURE 1 ) with 35–40 setae. About 20 anterior setae short, thin, naked; posterior setae ( Fig. 3A–B View FIGURE3 ) long, plumose; distalmost setae located at posteroventral angle of valves. Posteroventral angle ( Figs. 1C View FIGURE 1 , 3B View FIGURE3 ) with about 15 short setulae not organized into groups. Carapace and head shield covered by tubercles.

Head relatively small, round triangle in side view. In lateral view, rostrum protruding downwards. Ocellus smaller than eye. Distance from tip of rostrum to ocellus slightly greater than that between ocellus and eye.

Head shield of typical for genus shape ( Figs. 2F View FIGURE2 , 3D–E View FIGURE3 ), covered by tubercles. Rostrum short, with almost straight anterior margin. Posterior margin rounded. Two main head pores with a narrow connection between them; anterior pore somewhat larger than posterior ( Figs. 1D View FIGURE 1 , 3F View FIGURE3 ); PP up to 1 IP. Lateral head pores with bilobed asymmetric cosmaria, located at about 1 IP distance from midline, at level of anterior main head pore. Single posterior dorsal pore ( Fig. 3G View FIGURE3 ); minute aperture revealed by SEM examination, located behind posterior margin of head shield.

Labrum of moderate size, without lateral projections ( Figs. 1E View FIGURE 1 , 3C View FIGURE3 ). Labral keel wide, height only slightly exceeding width, with lateral indentations. Anterior margin of keel convex, with small blunt denticle in the upper third; apex rounded; posterior margin convex, without setulae.

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

Postabdomen ( Figs. 1F–G View FIGURE 1 , 4A–D View FIGURE4 ) short and wide; maximum height at postanal angle. Length about 2.1–2.2 height. Ventral margin straight. Basis of claws separated from distal margin by clear incision. Distal margin weakly convex to straight, distal angle broadly rounded. Dorsal margin weakly convex in postanal portion and unevenly concave in anal one, distal part 1.5–1.7 times longer than preanal one, postanal portion 1.5 times shorter than anal one. Preanal angle well-defined, postanal angle weakly defined. Preanal margin almost straight. Postanal margin with 5–6 narrow denticles, length of denticles decreases posteriorly, length of longest denticles about the width of postabdominal claw base. Anal margin with 3–4 groups of marginal spinules and setulae. Eight–ten lateral groups of setulae. In postanal portion fascicles narrow, composed of 3–8 setulae each, distance fascicles between them about width of fascicle; posteriormost setula very long, thick, with length about 2–2.5 widths of postabdominal claw base. In anal portion fascicles wider and spaced more closely, with shorter distalmost setula. Postabdominal claw slender, of moderate length, shorter than preanal portion of postabdomen. Basal spine short and slender, about 0.25 of the claw length. A long spinule located near the base of basal spine.

Antennule ( Figs. 1H View FIGURE 1 , 3D View FIGURE3 ) of moderate size, length about 2.5widths, with 3 clusters of short setulae at anterior face. Antennular seta of about 2/3 length of antennule, arising at 1/4 distance from the end. Nine terminal aestetascs, longest of them about half length of antennule.

Antenna ( Figs. 1I View FIGURE 1 , 3H View FIGURE3 ) with antennal formula: setae 0-0-3/1-1-3 and spines 1-0-1/0-0-1. Basal segment robust, with short seta between branches, branches relatively short, basal segments in both branches 1.5 times longer and thicker than others. Basal and middle segment of endopodite with clusters of short setulae. Seta arising from basal segment of endopodite reaching after the end of endopodite. Seta arising from middle segment of endopodite of similar size to shortest apical setae. One of apical setae on both branches significantly shorter and thinner than two others. Spine on basal segment of exopodite slightly longer than middle segment. Spines on apical segments as long as apical segments.

Thoracic limbs: five pairs.

Limb I ( Figs. 4F, 4G View FIGURE4 , 5A–C View FIGURE 5 ). Epipodite oval, with process two times longer than epipodite itself. Accessory seta 2 times shorter than ODL seta. ODL seta with short setulae in distal portion. IDL with two setae, seta 1 absent, seta 3 thick, curved, as long as ODL seta, ending in one thick and two–three slender long spines, seta 2 short, more thin, bearing 2–3 thick spines; in both setae basalmost spine longer and thicker than two others. Endite 3 with four very short setae, setae 1 and с thick, robust, setae a–b thin. Endite 2 with short seta d, setae e–f of similar length, moderately short, 2.5 times shorter than limb itself. Endite 1 with two long 2-segmented setae of similar size (g–i), setulated in distal part, long flat seta (j) pointed to the limb base. No inner setae found on endites 1–2. Ventral face of limb with 5–6 clusters of long setulae. Two ejector hooks, one of them much larger than other.

Limb II subtriangular ( Figs. 4G View FIGURE4 , 5D–E View FIGURE 5 ). Exopodite elongated, no exopodite seta found. Eight scraping spines, spines 1–3 largest, armed with thin spinules, setae 4–5 much shorter than setae 1–3, all armed with thin spinules. Spines 6–8 short, with wide bases and short distal part, spine 7 smaller than two others, short denticles observed only on spines 6–7. Distal armature of gnathobase with four elements. Filter plate II with seven setae, three distalmost setae much shorter than others.

Limb III. ( Fig. 5F–G View FIGURE 5 ) Epipodite rounded, with short process. Exopodite narrow, with six setae. Seta 3 longest, setae 4, and 5 about 1/2, 2/3 and 1/5 length of seta 3, setae 1–2 very short. Setae 1–4 plumose, seta 5 armed bilaterally with short hard setulae, seta 6 naked. Distal endite with 3 setae, two distalmost members slender, with blunt tips, without denticles in distal part, short bottle-shaped sensillum located between their bases, seta 3 much shorter, with long setulae. Basal endite with four outer setae (a–d) slightly increasing in length basally. Gnathobase not clearly separated from basal endite. Four inner setae (4–7) very short, slightly increasing in size basally; a sensillum near the base of distalmost seta. Distal armature of gnathobase with four elements, the first one an elongated, cylindrical sensillum; the second a geniculated seta; two others are very short short spines with fused bases. Filter plate with seven setae.

Limb IV ( Fig. 5H–I View FIGURE 5 ). Pre-epipodite setulated. Epipodite with finger-like process two times longer than epipodite itself. Exopodite rounded, with six setae. Seta 1–3 long, of similar length, setae 4–6 about two times shorter. Setae 1–4 flat, plumose, setae 5–6 thin, unilaterally armed with short setulae in distal portion. Inner portion of limb IV with three setae and small sensilla. Scraping seta (1) slender, without denticles in distal portion, first flaming-torch seta (2) wider and longer than other (3). Three soft setae, basalmost seta significantly larger than others. Gnathobase with two-segmented seta and a small hillock distally. Filter plate IV with five setae.

Limb V ( Fig. 5J View FIGURE 5 ). Pre-epipodite setulated, epipodite oval, with process longer than epipodite itself. Exopodite bilobed, with four plumose setae. Seta 1 very long, slightly longer than exopodite body, setae 2, 3 and 4 of about 2/3, 1/2 and 1/3 length of seta 1, respectively. Inner lobe moderately wide, with straight outer margin. At inner face, two short setae, distal seta 1.5 times longer than basal. Filter plate V absent.

Ephippial female and male unknown.

Size: length of adult female in studied material was 0.31–0.38 mm, height 0.25–0.28 mm.

Differential diagnosis. Anthalona vandammei sp. nov. differs from the most species of the genus in IDL setae armed with 3–4 very long spines and in limb II with very shortened distal portion spines 6–8; these characters are shared only by Neotropical A. brandorffi (Sinev & Hollwedel, 2002) and South-East Asian A. spinifera . A. vandammei sp. nov. clearly differs from both A. brandorffi and A. spinifera in IDL seta 3 with basal spine being much thicker and much longer than others, while in spines of IDL seta 3 are of similar thickness and length. A. vandammei sp. nov. differs from A. spinifera in the shape of postabdomen, which is narrowing basally in anal portion, in much longer posterior setae of valves, in posteroventral angle of valves armed with about 15 setulae only, and in having only two flaming-torch setae on limb IV. A. vandammei sp. nov. differs from A. brandorffi in longer setae e–f of limb I and in scraper 7 of limb II being only slightly smaller than scraper 6. Other differences between these two species are summarized in Table 1 View TABLE 1 .

Distribution. So far, the new species has been recorded in Lake Kud-Thing in Bueng Kan Province, North-East Thailand, and in Thungtong swamp in Surat Thani Province, Southern Thailand ( Maiphae et al. 2008).


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