Flavalona darkovi Neretina & Sinev 2021, sp. nov.
Creators: name: Neretina, Anna N.
name: Sinev, Artem Y.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Branchiopoda
Anomopoda
Chydoridae
Flavalona
Flavalona darkovi

description: Flavalona darkovi sp. nov.
(Figs. 1–3)
Alona costata species complex in Eggermont et al. (2011): p. 177.
Etymology. The taxon is named after Dr Andrey A. Darkov, the head of the Joint Ethiopian-Russian Biological Expedition (JERBE), for his great contribution to the development of hydrobiological studies in Ethiopia.
Type locality. A lake near Mountain of Konte (6.85495°N; 39.88085°E), Sanetti Tableland, Bale Mountains, Ethiopia. From this locality, 30 parthenogenetic females were collected on 14.02.2007 by O. Krylovich, B. Khassanov and A. Savinetsky.
Type material. Holotype. An adult parthenogenetic female deposited at the collection of Zoological Museum of Moscow State University, MGU Ml 237. The label of holotype is: “ Flavalona darkovi sp. nov., 1 parth. ♀ from the lake near Mountain of Konte (Ethiopia), HOLOTYPE ”.
Paratypes. Eight undissected parthenogenetic females preserved in 96% ethanol from type locality, MGU Ml 238; 7 undissected parthenogenetic females preserved in 96% ethanol from Crane Lake, near Mountain of Konte (6.893267°N, 39.9083°E), Bale Mountains, MGU Ml 239, collected on 10.02.2008 by O. Krylovich, A. Babenko, B. Khassanov and A. Savinetsky.
Other material studied. 10 parthenogenetic females from the small lake 2 near Mountain of Konte (6.854583°N, 39.89283°E), Bale Mountains, AAK M-0690, collected on 10.02.2008 by O. Krylovich, A. Babenko, B. Khassanov and A. Savinetsky; 10 parthenogenetic females from a small lake, Sanetti Camp Site, Mountain of Konte (6.8858°N, 39.7343°E), Bale Mountains, AAK M-2424, collected in 2012 by O. Krylovich.
Description. Parthenogenetic female. General. In lateral view, body yellow brownish, regularly ovoid, highly arched, maximum height at middle of body (body height/length ratio about 0.7 for adults) (Figs. 1A, 2A). In dorsal and anterior view body compressed laterally, dorsal keel absent (Fig. 2B). Dorsal margin uniformly curved, depression between head and rest of body absent (Figs. 1A, 2A). Posterodorsal and posteroventral angles expressed, obtuse (Figs. 1A, F; 2A). Posterior margin slightly convex or almost straight (Figs. 1A, F; 2A). Ventral margin almost straight; anteroventral angle rounded (Figs. 1A, F; 2A).
Head small (Figs. 1A, B; 2A, C). Rostrum relatively short; compound eye larger than ocellus; distance from tip of rostrum to ocellus almost equal to distance between centers of ocellus and eye (Figs. 1A, B). Head shield with broadly rounded posterior portion (Fig. 1C). Head shield with three connected major head pores and two lateral slit-shaped pores (Figs. 1C, D; 2E). Major head pores subequal in size, middle pore located closer to posterior pore. Connection between anterior pore and middle pore narrow, clearly expressed (Figs. 1C, D; 2E). Connection between middle pore and posterior pore broad. PP less than 0.5 IP. Lateral pores slit-like with semicircular pockets, length of lateral pores about 0.6–0.8 IP, depth of pore pocket about half of pore length (Figs. 1C, D; 2E).
Labrum large (Fig. 1E). Distal labral plate with tiny setulae. Labral keel with a regularly convex, not wavy anterior margin. Apex of keel rounded. Posterior margin of keel with two small rows of setulae (Fig. 1E).
Valve large, ovoid (Figs. 1A, F; 2A). A row of numerous setulated setae on inner face of ventral and anteroventral margins of valve (Figs. 1A, F, H, I). Short setulae on inner face of posteroventral angle and posterior margin of valve (Figs. 1A, F, G; 2G). On outer face, valves with moderately developed sculpture, consisting of longitudinal, sometimes anastomosing lines, located in posterior and ventral portion of valves (Figs. 1A, F; 2A, F).
Thorax relatively long (Fig. 1A).
Abdomen short (Fig. 1A).
Postabdomen moderately long, subrectangular, narrowing distally in postanal portion; length/height ratio about 2 (Figs. 1J, K; 2H). Ventral margin straight or slightly convex. Preanal and anal margin almost equal in length; postanal margin about 1.5 times longer than anal margin. Preanal and postanal angles well expressed. Basis of claws slightly inflated, bordered from distal margin by a clear incision (Figs. 1J, K; 2H, J). Postanal portion of postabdomen armed with robust composite marginal denticles, increasing in size distally (Figs. 1J, K; 2H, J). Proximally each denticle covered by short stiff spinules. Denticles in proximal portion of postanal margin significantly smaller and grouped in bunches (Figs. 1J, K; 2H, I). Postanal portion with row of 7–8 narrow clusters of thin short lateral setulae, distalmost setula in each cluster being longest; distance between postanal clusters 1.5 times greater than width of clusters. This row goes on anal margin, but setulae in the proximal clusters of this part have equal length (Figs. 1J, K; 2H, I).
Postabdominal seta long (almost subequal in length to ventral margin of postabdomen), bisegmented (Fig. 1J). Its distal segment covered by short fine setulae.
Postabdominal claw long (subequal in length than postanal margin of postabdomen), slightly curved (Figs. 1J, K; 2H, J). Its dorsal margin armed in outer side with a row of fine teeth, decreasing in size distally (Figs. 1L, 2J), and in inner side with a row of relatively robust teeth (Fig. 2J). Basal spine short, its length less that width of claw base (Figs. 1L, 2J). Basis of claw without a bunch of setulae (Figs. 1L, 2J).
Antenna I relatively long, not reaching tip of rostrum, with four distinguishable rows of setulae (Figs. 1A, B, M; 2K). Antennular sensory seta slender, arising subdistally, shorter than antennular body (Figs. 1M, 2K). Nine aesthetascs, two of them longer than the rest, but shorter than antennular body. All aesthetascs tips projecting beyond tip of rostrum (Figs. 1A, B).
Antenna II typical for Chydoridae (Figs. 1A, B, N–P; 2L). Coxal part folded, with two sensory setae. Basipodite robust, weakly setulated, with a short spine between branches of antenna. Antennal formula: setae 0-0-3/1-1-3; spines 1-0-1/0-0-1. Branches of antenna subequal in size, all segments cylindrical, covered by fine setulae; middle endopod segment with a bunch of relatively long setulae. In adults and juveniles seta of proximal segment of endopod shorter than endopod branch, reaching only middle of distal endopod segment. Seta of middle segment long, almost two times longer than endopod branch, but not reaching tips of apical setae. Apical setae subequal in thickness to seta of middle endopod segment. One seta on each branch relatively short, subequal in length to seta of middle endopod segment. Other four apical setae almost two times longer than seta of middle endopod segment. Spine on proximal exopod segment short, not reaching the end of middle exopod segment. Spines on both apical segments of exopod and endopod long and thick, subequal in length to distal exopod and endopod segments.
Thoracic limbs: six pairs (Figs. 3A–M).
Limb I relatively large (Figs. 3A, B). Accessory seta short. Outer distal lobe (ODL) conical and large, bearing a single bisegmented seta with minute setulae on distal segment. Inner distal lobe (IDL) with three bisegmented setae of different length: two long setae armed by relatively short and thick setulae distally and a sole short seta. Endite 4 (e4) with three posterior setae (a–c) and a single anterior seta (1). Endite 3 (e3) with three posterior setae (d–f) and a short anterior seta (2). On endite 2 (e2) three bisegmented posterior setae (g–i) (among which seta “i” very short) and an anterior seta (3). Endite 1 (gnathobase) reduced, without setae. Two setulated ejector hooks of unequal size (ejh).
Limb II subtriangular (Fig. 3C). Exopodite (ext) small, ovoid, with a single rudimentary seta. Inner portion of limb with eight scrapers (1–8). Distal armature of gnathobase with four setae; one of them represented by a small sensillum. Filter plate with seven setae: distalmost seta thick and short, with especially long setulae; next seta also shorter than other setae increasing in size proximally.
Limb III (Fig. 3D–F) with ovoid epipodite. Exopodite (ext) almost round, with five distal setae (among which two middle setae short), and two lateral setae (Figs. 3D, E). Distal endite (in terms of Kotov (2013)) with three anterior setae (Figs. 3D, F): setae 1 and 2 supplied with short stiff setulae distally, a small sensillum between their bases, and seta 3 with fine long setulae. Proximal endite with four small anterior setae; a small sensillum near seta 4. Four soft setae on posterior face of limb (a–d). Distal armature of gnathobase with three setae and a thick sensillum. Filter plate with seven setae of subequal size.
Limb IV (Fig. 3G–J) with ovoid bilobed densely setulated preepipodite. Epipodite (epp) ovoid, with long finger-like projection (Figs. 3G, H). Exopodite (ext) almost round, with three distal and three lateral setae. Inner distal portion with four anterior setae: distalmost seta 1 stout, naked; setae 2–4 shorter with inflated basal portion and relatively thick setulae distally (Figs. 3G, I, J). Three thin setae (a–c) on posterior limb face. Distal armature of gnathobase with two elements, one long bisegmented seta and a blunt process near it. Filter plate with five setae subequal in size (Figs. 3G, I, J).
Limb V (Fig. 3 K, L) with ovoid bilobed densely setulated preepipodite (pep). Epipodite (epp) ovoid, with long finger-like projection. Exopodite (ext) bilobed, with four plumose setae: three long lateral setae separated from a single relatively short distal seta via densely setulated convex lobe (Fig. 3K). Inner limb portion as elongated flap, with setulated margin, with two setulated setae (1–2) of unequal length. Filter plate with three small setae of different length.
Limb VI (Fig. 3M) represented by ovoid elongated lobe with setulated margin. Its length about twice maximum width.
Ephippial female and male. Unknown.
Size. Adult parthenogenetic females up to 0.59 mm of length. Holotype 0.58 mm of length.
Variability. No significant variability between investigated females from four localities in Bale Mountains was found.
Differential diagnosis. F. darkovi sp. nov. belongs to the costata -clade of Flavalona and clearly differs from species of the rustica -clade in long lateral head pores with large pockets (Sinev & Dumont 2016). Within the costata-clade, F. darkovi sp. nov. differs from Australian F. setigera (Brehm, 1931), in three major head pores; from F. costata (Sars, 1862) and F. margipluma (Sousa, Santos, Güntzel, Diniz, de Melo Junior & Elmoor-Loureiro, 2015) in semicircular shallow pockets of lateral pores; from F. weltneri (Keilhack, 1905) in shape of postabdomen; from F. natalensis (Sinev, 2008) in thin longitudinal lines on carapace; and from F. cheni (Sinev, 2009) in shorter lateral head pores and smaller IP/PP ratio.
Distribution and ecology. The species is known to date from several localities in Bale Mountains (3960 – 4128 m.a.s.l). Flavalona darkovi sp. nov. was found in the samples together with Daphnia izpodvala Kotov & Taylor, 2010. With high probability, both these species are endemic cladocerans for Bale Mountains. They inhabit small permanent water bodies with macrophytes, located at an altitude of about 4000 m.a.s.l.
description: Published as part of Neretina, Anna N. & Sinev, Artem Y., 2021, A new species of Flavalona Sinev & Dumont, 2016 (Crustacea: Branchiopoda) from Bale Mountains, Ethiopia, pp. 113-122 in Zootaxa 4948 (1) on pages 114-119, DOI: 10.11646/zootaxa.4948.1.6, http://zenodo.org/record/4616195