Coronatella (Ephemeralona) elegans elegans ( Kurz, 1875 ) elegans (Kurz, 1875
Sinev, Artem Y., 2020, Revision of the elegans-group of Alona s. lato and its status as a subgenus of Coronatella Dybowski & Grochowski, 1894 (Cladocera: Anomopoda Chydoridae), Zootaxa 4732 (4), pp. 501-526 : 504-511
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|Coronatella (Ephemeralona) elegans elegans ( Kurz, 1875 )|
(syn. Alona moniezi Richard, 1888 ).
Kurz, 1875: 51-52, Pl. II, Fig. 1 View FIGURE 1 ( Alona ); Richard, 1988: 46-47; Gauthier, 1928: 321, Fig. 40 ( Alona bukobensis ); Herbst, 1964: 40-48, Fig. 1 View FIGURE 1 -12 ( Alona elegans arcuata ); Smirnov, 1971: 352, Fig. 399-400 ( Alona rectangula elegans ); Dumont, Laureys & Pensaert 1979: 261-254, Fig. 3-4 View FIGURE 3 View FIGURE 4 ( Alona ); Margaritora, 1985: 301-304, Fig. 118-119 ( Alona ); Flössner 1972: 312-314, Fig. 148 ( Alona ); Alonso 1996: 332-335, Fig. 148 ( Alona ); Flössner 2000: 303-306, Fig. 112 ( Alona ); Marrone, Barone & Naselli-Flores, 2005: 1035-1036, Fig. 3 View FIGURE 3 ( Alona ); Hudec 2010: 313-316, Fig. 75 ( Alona ).
Type locality. Bohemia (Czechia) .
Type material. Lost.
Material examined. Over 50 parthenogenetic and ephippial females, 3 males from Mainzer Sand, Germany, coll. F. Marrone, AAK-M-2649; over 100 parthenogenetic and ephippial females, and over 30 males from Chateau du Vernet, Allier, Auvergne, France, 09.05.1887, collected by J. Richard, DGF 744 (syntypes of Alona moniezi Richard, 1888 according to Kotov & Ferrari (2010)); over 100 parthenogenetic and ephippial females, and over 20 males from Laguna de El Hito, near El Hito town, Cuenca, Castilla La Mancha, Spain, 17.04.1997, coll. M. R. Miracle; over 50 parthenogenetic females from a temporary pond in Castellon, Comunidad Valenciana, Spain, 40°26’25.7” N, 0°10’31.7” E, 15.01.2019, coll. A. Y. Sinev & M. Sahuquillo; over 100 parthenogenetic and ephippial females, and 7 males from Draa-Boultif temporary pond, Batha, Algeria, 35°50’6.60”N, 06°22’25.56”E, 03.03.2015, coll. M. Amarouayache, AAK-2016-005.
Description. Parthenogenetic female. General. In lateral view, body oval, moderately compressed laterally, low in juveniles ( Fig. 1A, D View FIGURE 1 ), moderately high in adults ( Fig 1 View FIGURE 1 E-F, 2A-B, 5A). Maximum height at middle of body. Height-length ratio 0.65–0.7 in adults. Dorsal margin convex, postero-dorsal and postero-ventral angles broadly rounded. Posterior margin convex, ventral margin almost straight, antero-ventral angle rounded. Ventral margin ( Fig. 1G View FIGURE 1 ) with 40-55 setae. About 10 anterior setae longer than others, next 10 setae short, posterior setae of moderate length ( Fig. 1H View FIGURE 1 ). Postero-ventral angle ( Fig 1I View FIGURE 1 ) with over 50 setulae not organized into groups. Carapace covered by thick, densely spaced longitudinal lines, distance between lines only slightly exceed widths of the lines ( Fig. 2C View FIGURE 2 ).
Head relatively small, triangle-round in lateral view, rostrum short, pointing downward. Eye and ocellus of similar size, in many specimens ocellus larger than eye. Distance from the tip of rostrum to the ocellus equal or slightly greater than that between the ocellus and the eye.
Headshield with maximum width behind mandibular articulation, without any prominent sculpture ( Fig. 1B View FIGURE 1 , J- K, 2C). Rostrum short, broadly rounded. Posterior margin of headshield broadly rounded, sometimes slightly wavy. Three narrowly connected major head pores ( Fig. 1C View FIGURE 1 , L-M, 2D), middle pore slightly smaller than others, located at the middle between others. PP about 1.0–1.2 IP in adults. Lateral head pores slightly elongated, located at about 2 IP distance from midline, at the level between anterior and middle major head pore or before anterior pores.
Labrum relatively large ( Fig. 3A View FIGURE 3 ). Labral keel of moderate width (height/width ratio about 1.5), with a rounded apex. Anterior margin of keel convex, posterior margin without clusters of setulae.
Thorax two times longer than abdomen. Dorsal surface of abdominal segments not saddle-shaped. No abdominal projections.
Postabdomen ( Fig. 2E View FIGURE 2 , 3 View FIGURE 3 B-C, 5B) short, of moderate width, with almost parallel margins in anal portion, narrowing in postanal portion, with broadly rounded dorsodistal angle. Length about 2.5–2.8 heights. Ventral margin from almost straight to weakly convex. Bases of claws bordered from distal margin by clear incision. Distal margin almost straight. Dorsal margin with distal part about 2 times longer than preanal one; postanal and anal portions of similar length. Postanal portion weakly convex to straight; anal portion weakly concave. Preanal angle well defined; postanal angle weakly defined. Postanal margin ( Fig. 2F View FIGURE 2 ) with 6-8 clusters of 2-4 elemental marginal denticles, decreasing in size basally; length of longest elements less than width of postabdominal claw base. In some specimens several such groups are substituted by composite denticles. Anal margin with 5-7 groups of setulae. About 10 lateral fascicles of setulae; 4-5 distalmost fascicles wide, closely spaced, with setulae longer than marginal denticles, with distalmost setula only slightly thicker than others. Additional groups of smaller fascicles in anal portion above the main row. Postabdominal claw weakly curved, of moderate length, as long as preanal portion of postabdomen. Basal spine long and thin, about 1/3 of length of claw, a cluster of 3-6 long setulae located near its base.
Antennule ( Fig. 3D View FIGURE 3 ) comparatively large, almost reaching tip of rostrum, with 3-4 clusters of long setulae at anterior face. Length/width ratio about 2.5. Antennular sensory seta slender, three times shorter than antennule, arising at about 2/3 distance from the base. Nine aesthetascs, three longest about 2/3 length of antennule.
Antenna short ( Fig. 2G View FIGURE 2 , 3 View FIGURE 3 E-F). Antennal formula, setae 0-0-3/1-1-3, spines 1-0-1/0-0-1. Basipodite robust, branches short and stout. Basal segments of both branches almost two times longer than middle and apical segments. Seta arising from basal segment of endopodite thin, much longer than endopodite. Seta arising from middle segment of endopodite as long as shortest apical setae. Both apical segments with one shorter and two longer setae of similar thickness. Spine on basal segment of exopodite slightly shorter than middle segment. Spines from apical segments longer than apical segments.
Thoracic limbs: five pairs.
Limb I ( Fig. 4 View FIGURE 4 A-B, 5C) of moderate size. Epipodite oval, with process two times longer than epipodite itself. Accessory seta long and thick, almost as long as ODL seta. ODL seta with minute setulation. IDL with 3 setae; seta 1 very small; seta 3 as long as ODL seta; seta 2 slightly shorter than seta 3. Setae 2 and 3 armed thin spinules. Endite 3 with four setae, seta 1 shorter than others. Endite 2 with seta “d” as long as setae of endite 3; seta “e” very long, almost as long as limb itself; seta “f” about 3/4 length of seta “e”. Endite 1 with 2 distally setulated 2-segmented setae (g-h) and a long flat seta (i) as long as seta 1. No naked inner setae (2-3) and sensillae on endites 1 and 2. Six rows of thin long setulae on ventral face of limb. Two ejector hooks, one longer than other. Maxillar process with single seta.
Limb II ( Fig. 4C View FIGURE 4 ). Exopodite elongated, with rudimentary seta. Eight scraping spines armed with thin setulae, increasing in length distally. Small seta located near the base of scraper 1. Distal armature of gnathobase with 4 elements. Filter plate with 7 setae, the 2 posteriormost setae considerably shorter than others.
Limb III ( Fig. 4 View FIGURE 4 D-F). Epipodite oval with short process. Exopodite subrectangular, with 6 setae. Seta 3 being longest; setae 4 and 5 of similar length, about 2/5 length of seta 3; seta 5 shorter or longer than seta 4 in different specimens; seta 1 and 6 about 1/5 length of seta 3, seta 2 very short. Setae 1-4 plumose, seta 5 armed with two types of setulae in distal portion, seta 6 armed with short setulae in dorsal portion. Distal endite with three setae; two sensillae located between their bases. Two distalmost setae (1–2) slender, sharp, of similar length, with long denticles in distal part; basalmost seta 2 times shorter, flattened and setulated in distal portion. Basal endite with 4 outer setae (a–d) increasing in length basally. Gnathobase not clearly separated from basal endite. Four inner setae (4–7) 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 short spines with fused bases. Filter plate with seven setae.
Limb IV ( Fig. 4 View FIGURE 4 G-H). Preepipodite setulated; epipodite oval, with process longer than epipodite itself. Exopodite rounded, with 6 setae; seta 3 longest; seta 1 about 2/3 length of seta 3; seta 2 and 5 about 1/2 length of seta 3; setae 4 and 6 slightly shorter than seta 5. Setae 1-4 flattened, plumose; setae 5 and 6 slender, with thicker setulae in distal portion. Inner lobe of limb IV with 4 setae and strongly curved sensillum ( Fig. 4H View FIGURE 4 ). Distalmost seta (1) slender, sharp, flaming-torch seta (2-4) with elongated basal portion and shortened distal portion, armed with 9-11 thin setulae each, seta 2 larger than two others. Small sensillum located between bases of setae 3-4. Three soft setae (a-c) increasing in size basally. Gnathobase with 2-segmented seta, and a small hillock distally. Filter plate with 5 setae.
Limb V ( Fig. 4I View FIGURE 4 ). Preepipodite setulated, epipodite oval, with process longer than epipodite itself. Exopodite elongated oval, not divided into two lobes, with four plumose setae with thick basal portion, decreasing in size basally. Inner limb portion an oval lobe, with setulated inner margin. At inner face, two setae, one 2 times longer than another. Filter plate with one seta.
Ephippial female ( Fig. 1N View FIGURE 1 , 2H View FIGURE 2 ) with body slightly higher than parthenogenetic female; dorsal margin with depression between valves and headshield. Ephippium yellow-brown in preserved specimens, with moderately developed egg locules, covered by prominent longitudinal lines thinner and less densely spaced than on the rest of valves.
Male. Juvenile males of instar I and II habitually similar to juvenile females ( Fig. 1 View FIGURE 1 O-P). Adult male ( Fig. 1Q View FIGURE 1 , 5D View FIGURE 5 ) with low oval body, lower than in female, height/length ratio about 0.6-0.65. Ocellus and eye smaller than in female.
Postabdomen. In juvenile males of instar I similar to that of juvenile female ( Fig. 3G View FIGURE 3 ), with sperm duct open- ings located before the middle of ventral margin. In juvenile males of instar II, shorter than that of female ( Fig. 3H View FIGURE 3 ), with gonopores located closely to the end of the postabdomen, with notch on ventral margin in region of gonopores. Armament of postabdomen and postabdominal claw same as in female in both juvenile instars. In adult ( Fig. 3J View FIGURE 3 , 5E View FIGURE 5 ) postabdomen short, slightly narrowing distally in postanal portion, with broadly rounded dorso-distal angle. Ventrodistal angle well-defined, obtuse. Sperm duct openings located ventrally at the end of postabdomen. Postanal angle not defined, preanal angle well-defined. Distal part of postabdomen 1.5 times longer than preanal, anal portion 1.5-2 times longer than postanal. Clusters of short setulae in place of marginal denticles, lateral fascicles of setulae same as in female. Postabdominal claw ( Fig. 3 View FIGURE 3 J-K, 5E) 2 times shorter than in female, its tip of variable morphology, either pointed or blunt with several setulae. Basal spine long, about 0.4 length of claw, a cluster of 3-6 long setulae located near its base.
Antennule in juvenile male of instar I same as in female; in juvenile male of instar II ( Fig. 3I View FIGURE 3 ) thicker than in female, with 9 terminal aestetascs and anlage of male seta arising at 2/3 length from the tip. In adult ( Fig. 3L View FIGURE 3 ) thicker than in female, with 10 terminal and 2 lateral aesthetascs. Male seta arising at 3/4 length from tip, about 1/4 of antennule length.
Thoracic limb I. In instar I ( Fig. 4J View FIGURE 4 ) with short anlage of copulatory hook, IDL same as in female. In instar II ( Fig. 4K View FIGURE 4 ), copulatory hook curved. Ventral face of limb with anlage of copulatory brush seta and a peculiar hillock above it, not present in any other instar. IDL with anlage of male seta, seta 1 not found; setae 2-3 same as in female. In adult ( Fig. 4 View FIGURE 4 L-M) with short U-shaped copulatory hook two times shorter than limb itself. Copulatory brush present, copulatory brush seta rather long. Ventral face of limb below them with double row of short thick setulae. Inner distal lobe without seta 1; setae 2 and 3 much shorter and thinner than in female, of similar length; male seta thick, strongly curved, longer and two times thicker than setae 2-3.
Size. In instar I juvenile female length 0.32-0.35 mm, height 0.20-0.22 mm; in instar II juvenile female length 0.39-0.44 mm, height 0.26–0.28 mm; in adult parthenogenetic female length 0.46–0.63 mm, height 0.33–0.42 mm. In instar I juvenile male length 0.32-0.35 mm, height 0.20-0.22 mm; in instar II juvenile male length 0.39-0.43 mm, height 0.24–0.27 mm; in adult male, length 0.39–0.45 mm, height 0.24-0.29 mm.
Taxonomic notes. Study of Richard syntypes of Alona moniezi revealed no significant differences from other studied populations of C. (E.) elegans , and I inclined to treat this form as a synonym of C. (E.) elegans . Van Damme et al (2011a) redescription of A. moniezi based on slides from Richard’s collection, in my opinion, revealed as the unique significant difference from C. (E.) elegans the shorter seta on basal segment of antenna endopodite (see Van Damme et al. 2011a: Fig.), but studied here syntypes all have typical long seta.
Distribution. This species was recorded from Czechia ( Kurz 1875), Germany ( Flössner 1972, 2000), Slovakia ( Hudec 2010), Belgium, France and Slovenia ( Brancelj & Dumont 2007), Italy and Sicilia (Margaritora 1975; Marrone et al. 2005), Iberian Peninsula ( Alonso 1996), Morocco ( Ramdani 2001), Algeria ( Ghaouaci et al. 2018), Tunisia ( Dumont et al. 1979), Israel and Sinai region of Egypt ( Bromley 1993). Sars (1903) reported Alona elegans from water bodies in Akmolinsk (now Nur-Sultan), Khazakhstan, but his drawings ( Sars 1903: Pl. VIII, Fig. 3, 3a View FIGURE 3 ) while clearly belonging to species of subgenus Ephemeralona subgen. nov., are not detailed enough for identification at species level. Temporary ponds and pools inhabited by the species are commonly lost during land conversion, and C. (E.) elegans now probably became rare or even extinct in many regions of Central Europe, for example, it was not found during recent intensive survey of Belgium cladocera ( Louette et al. 2007).
Departamento de Geologia, Universidad de Chile
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