Alona setulosa arangureni, Sinev, Artem Y. & Fuentes-Reinés, Juan M., 2016
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publication ID |
https://doi.org/ 10.11646/zootaxa.4121.1.2 |
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publication LSID |
lsid:zoobank.org:pub:81B43683-DF38-4595-BFA8-0D4DF9E7E426 |
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DOI |
https://doi.org/10.5281/zenodo.5679997 |
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persistent identifier |
https://treatment.plazi.org/id/03B487B5-FFC0-FFEE-FF02-F9D3FBF6FE7D |
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treatment provided by |
Plazi |
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scientific name |
Alona setulosa arangureni |
| status |
subsp. nov. |
Alona setulosa arangureni ssp. nov.
( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )
Etymology. The new subspecies is named after the Colombian researcher Dr. Nelson Aranguren, for his extensive work on the zooplankton from aquatic systems of Colombia and for his legacy and leadership of new generations of planktologists.
Type locality. Laguna Navio Quebrado, La Guajira Department, Colombia (11º25’N and 73º5’W). From this locality, 30 parthenogenetic females, 3 ephippial females, and 20 adult males were collected in June and October of 2012 by J. M. Fuentes-Reinés.
Type material. Holotype: parthenogenetic female deposited at the Museo de Colecciones Biológicas de la Universidad del Atlántico, Colombia, UARC 246M.
Allotype: adult male from type locality, UARC 247M.
Paratypes: 5 undissected females in alcohol, UARC 248M; 1 dissected female, UARC 243M-257M, 3 undissected ephippial females in alcohol, UARC 249M; 3 adult males, UARC 250M; 1 dissected male, UARC 251M- 252M.
Description. Parthenogenetic female. In lateral view, body ovoid ( Fig. 1 View FIGURE 1 A, 2A), maximum height in middle, height/length about 0.66–0.76 in adults. Dorsal margin of valves generally uniformly curved, postero-dorsal angle smoothed, postero-ventral angle broadly rounded. Ventral margin of valves with 40–45 setae of different size in different regions of the margin. Posteroventral angle of valves with about 100 short setules of similar length, not differentiated into groups. Valves oblique, without any sculpture.
Head small, not keeled, rostrum short and blunt. Compound eye and ocellus subequal in size, distance from tip of rostrum to ocellus somewhat larger than between ocellus and eye.
Head shield elongated, length/width ratio about 1.5–1.6, rostrum short, broadly rounded, posterior portion widely rounded, with wavy margin ( Fig. 1 View FIGURE 1 B, 2B). Three major head pores of equal size, with interrupted connection between them ( Fig. 1 View FIGURE 1 C–D), distance from posterior pore to posterior margin of head shield (PP) about 0.4–0.5 distance between anterior and posterior pores (IP). Lateral head pores minute, located about 1.1–1.5 IP from midline, at the level of anterior major head pore.
Labrum ( Fig. 1 View FIGURE 1 E, 2C): distal labral plate without setulation. Labral keel moderately wide, with height about 1.3 widths. Anterior margin convex, apex rounded or blunt, posterior margin convex, without clusters of short setules. Postabdomen ( Fig. 1 View FIGURE 1 F, 2D) with almost parallel margins, moderately wide, length/width ratio about 2.5–2.6. Ventral margin straight or weakly convex. Dorsal margin convex in preanal part, concave in anal part, straight in postanal part. Distal margin almost straight; dorso-distal angle weakly prominent, almost right, with rounded tip.
Preanal angle well-expressed, postanal angle weakly defined. Distal portion 1.5 times longer than preanal margin; anal and postanal portions subequal in length. Postanal margin provided with 7–8 marginal denticles; anal margin with 4–5 clusters of setulae ( Fig. 1 View FIGURE 1 G). Each postanal denticle with 1–3 short spines near the base. Length of postanal denticles evenly decreases basally; length of distalmost denticle slightly less than width of postabdominal claw base. Postanal portion with 5–6 wide, closely spaced lateral fascicles of long setulae; distalmost setule in each fascicle being the longest and thickest, 1.5 times longer than neighboring marginal denticles. Postabdominal claw ( Fig. 1 View FIGURE 1 H) regularly curved, somewhat longer than preanal portion of postabdomen, with fine setulation along ventral margin. Basal spine length about 0.33 of claw length.
Antennule ( Fig. 2 View FIGURE 2 E) with four clusters of setules on inner face. Antennular sensory seta slender, arising at 2/3 distance from the base. Nine aesthetascs, the longest of them about 0.8 length of antennule. All aesthetascs projecting beyond anterior margin of the head shield.
Antenna of moderate size ( Fig. 2 View FIGURE 2 F). Antennal formula: setae 0-0-3/1-1-3; spines 1-0-1/0-0-1. In both branches, length of segments decreasing distally. Seta arising from basal segment of endopodite thin, reaching to the end of endopodite. Seta arising from middle segment of endopodite of same size with apical setae. Basal and middle segments of endopodite with clusters of hard setules. Apical setae of both branches of similar thickness. Spine on basal segment of exopodite shorter than middle segment. Apical spines longer than apical segments. Mandible elongated; distal portion with sharp denticles ( Fig. 3 View FIGURE 3 A)
Thoracic limbs: five pairs.
Limb I ( Fig. 1 View FIGURE 1 I, 3B–D). Epipodite oval. ODL seta longer than IDL setae. IDL with three setae; seta 1 short; setae 2–3 long, of similar length, armed with thin setulae in distal portion. Endite 3 with four setae subequal in length. Endite 2 with three setae of different length, middle one (e) longer than ODL seta. Endite 1 with two 2- segmented setae (g–h), both setulated in distal part, without a flat plumose seta shifted to the limb base. Fascicles of thin setulae on inner face of limb, plus bunches of longer and more robust setulae at ventral margin of limb. Two unequal ejector hooks.
Limb II ( Fig. 3 View FIGURE 3 E) exopodite narrow elongated lobe with slender seta of half length of exopodite. Inner portion of limb (“endopodite”) with eight scraping spines; scrapers 1–4 long, increasing progressively in length distally; scraper 5 longer than 4; scrapers 6–8 short, subequal in length. Distal armature of gnathobase with four elements. Filter plate II with seven setae, the posteriormost member considerably shorter than others.
Limb III ( Fig. 3 View FIGURE 3 F). Epipodite oval, without projection. Exopodite with seven setae, seta 3 being longest (Fig. 6D). Distal endite with 3 setae (Fig. 6E); distalmost and middle setae of same size, slender and sharp, with denticles in distal part; basalmost seta short, geniculated, with thin setulae. Basal endite with 4 stiff, feathered in distal part setae, increasing in size in basal direction. Gnathobase filter plate of 7 setae.
Limb IV. Pre-epipodite setulated. Epipodite ovoid. Exopodite subquadrangular, with six setae; seta 1–3 long, of similar length; setae 4–6 about two times shorter; seta 5 longer than seta 6. Setae 1–4 flat, plumose; setae 5–6 thin, with short setulae in distal portion. Inner portion of limb IV with four setae and small sensillum ( Fig. 1 View FIGURE 1 J). Scraping seta (1) slender, sharp; flaming-torch setae (2–4) with well-developed distal portion, bearing 6–7 long setulae each; first flaming-torch seta (2) wider than the two other (2–3). Gnathobase with two-segmented seta and a small hillock distally. Gnathobase filter plate of 5 setae.
Limb V. Preepipodite setulated, epipodite oval. Exopodite oval, with four plumose setae. Setae 1–3 long, subequal in length, seta 4 short, three times shorter than seta 1. Inner lobe as oval lobe. At inner face, two setae, distal seta two times longer than basal. Filter plate V absent.
Ephippial female. Habitus similar to that in parthenogenetic female, with a bit elongated body (body height/ body length = 0.56–0.67), ephippium slightly additionally pigmented in brown, with a single egg.
Male. Body ( Fig. 1 View FIGURE 1 K, 4A) low oval, with maximum height at the middle, height/length ratio about 0.65. Valve with naked setae at postero-ventral angle, followed by a submarginal row of strong spinules of similar size.
Postabdomen ( Figs. 1 View FIGURE 1 L, 4B–C) of moderate size, slightly narrowing in anal portion, subrectangular in postanal portion. Length about 3.1 height. Postanal angle not defined, preanal angle well-defined. Postabdominal claw situated on small protrusion in ventral portion of convex distal margin. The sperm ducts open above the protrusion at distal margin of postabdomen. Dorso-distal margin of postabdomen straight; distal part of postabdomen 1.35 times longer than preanal; postanal portion equal or slightly shorter than anal portion. Clusters of short setulae in place of marginal denticles; lateral fascicles of setulae same as in female. Postabdominal claw weakly curved, shorter and more robust than in female. Basal spine about 0.3 length of claw.
Antennule broader than in female, with 10 long terminal aesthetascs and 2 lateral aestetascs of similar length. Male seta subterminal, arising at 1/4 length from tip, not reaching the end of antennule.
Thoracic limb I ( Fig. 4 View FIGURE 4 D) with U shaped copulatory hook with its free arm little longer than basal one. Row of 14–17 short setulae on ventral face of limb under copulatory brush. First IDL seta absent; 2nd and 3rd setae subequal in length, 2 times shorter and thinner than in female; male seta of same size as 2nd seta. Size. Length of adult parthenogenetic females 0.32–0.42 mm, of ephippial females 0.32–0.38 mm, of adult males 0.28–0.29 mm.
Variability. A single parthenogenetic female without connection between posterior and central main head pore was found.
Differential diagnosis. O. setulosa arangureni ssp. nov. differs from O. setulosa setulosa (Megard, 1967) (see Sinev, 2009) by: (1) greater IP/PP ratio in both sexes; (2) posterior margin of labrum without clusters of short setulae; (3) longer postabdomen, with length/height ratio about 2.7–3; (4) male postabdomen with straight dorsal margin in whole distal portion. O. setulosa arangureni ssp nov. is similar to O. glabra (Sars, 1901) in general shape and morphology of postabdomen, but, like nominative subspecies, differs from it by interrupted connections between head pores. For other differences between these taxa see Table 1 View TABLE 1 . Like nominative subspecies, A. setulosa arangureni ssp nov. clearly differs from other South American Ovalona species: O. altiplana ( Kotov, Sinev & Berrios, 2010) ; O. kaingang (Sousa, Elmoor-Loureiro & Santos, 2015) ; and O. nigra (Smirnov, 1996) by interrupted connection between main head pores.
Distribution and ecology. To the date, the subspecies is known to the date from La Guajira Department in Colombia. The type locality, the Laguna Navio Quebrado, is a small (surface area of 10.7 km 2) lagoon system, with shallow water bodies (depth 0.3–0.7 m) covered by submerged and floating aquatic vegetation; temperature varies over the seasons in the range of 28 and 31 °C; during the sampling, pH was 7.8–8.3 and salinity between 0–28 PSU, being 0 in the mouth of the river and 28 near the communication to the sea.
TABLE 1. Main morphological differences between O. setulosa arangureni ssp nov., O. setulosa setulosa (Megard, 1967) and O. glabra (Sars, 1901).
| O. setulosa arangureni ssp. nov. | O. setulosa setulosa | O. glabra | |
|---|---|---|---|
| Female | |||
| Body height/body length | 0.66–0.76 | 0.64–0.67 | 0.62–0.66 |
| Ventral margin of valves | with 40–45 setae | With 35–45 setae | With 40–50 setae |
| PP/IP ratio | 0.4–0.5 IP | 0.3–0.4 IP | 0.2–0.3 |
| Major head pores | Connection interrupted in several places | Connection interrupted in several places | Connection continuous |
| Distance from lateral head pore to midline | 1.1–1.5 IP | 1.2 IP | 0.9–1 IP |
| Labral keel | Without clusters of setules on the posterior margin | With clusters of setules on the posterior margin | Without clusters of setules on the posterior margin |
| Length of postanal portion of postabdomen | About 1–1.1 of anal portion length | About 1 of anal portion length | About 1.2–1.4 of anal portion length |
| Distal angle of postabdomen | Acute or right | Right | Acute |
| Flaming-torch setae of limb IV | With developed distal portion | With developed distal portion | With reduced distal portion |
| Male | |||
| Postabdomen | Of same height along all anal portion, anal portion of dorsal margin parallel to ventral margin | Height weakly increases basally in anal portion | Height strongly increases basally in anal portion |
| Length/height ratio of postabdomen | 2.8–3 | 2.5 | 2.6 |
| Marginal setules of postabdomen | All setules in postanal groups short, of same length | All setules in postanal groups short, of same length | Distal setules in postanal groups long, length of setules decreases basally |
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