Coronatella poppei ( Richard, 1897 )

Sousa, Francisco Diogo Rocha, Elmoor-Loureiro, Lourdes Maria Abdu & Santos, Sandro, 2015, Redescription of Coronatella poppei (Richard, 1897) (Crustacea, Branchiopoda, Chydoridae) and a revision of the genus in Brazil, with descriptions of new taxa, Zootaxa 3955 (2), pp. 211-244 : 214-219

Coronatella poppei ( Richard, 1897)

( Figs. 2–3 ; 12)

Alona Poppei Richard 1897 , p. 290–292, figs. 37–38; Smirnov (1971), p. 346, fig. 389; Rey & Vasquez 1986, p. 155, figs. 1– 12.

? Alona poppei Richard in Delachaux 1919, p. 29, Pl. 2: figs. 4–5. Coronatella poppei (Richard) in Van Damme & Dumont (2008b), p. 33. (see Kotov & Ferrari 2010)

Material examined. Thirty adult parthenogentic females, three juvenile females and two males from the Tranque Recreo, Limache, Chile (33° 05' 10.1"S, 71° 22' 37.6"W), material collected by Lourdes M. A. Elmoor-Loureiro on 12/10/2012. One adult parthenogenetic female from the Lagoa dos Patos (30° 08' 32.8"S, 51° 13' 36.4"W), Porto Alegre, Rio Grande do Sul, Brazil, material collected by Lourdes M. A. Elmoor-Loureiro on 27/12/2001 (EL00716).

Type material. Neotype. undissected, adult parthenogenetic female in a tube with 90% ethanol deposited at the Museum of Zoology of the University of São Paulo under access number MZUSP 32925. The label of the neotype is: “ Coronatella poppei , 1 parth. ♀ from to Tranque Recreo, Limache, Chile. Neotype ”. Richard’s original material is lost ( Kotov & Ferrari 2010).

Other material from the neotype locality. About 20 females and two males deposited at Elmoor-Loureiro’s collection (EL02334). Many slides containing dissected individuals deposited at the Laboratório de Biodiversidade Aquática, Universidade Católica de Brasília ( CLLA 035 to CLLA 041).

Diagnosis. Female. Animal medium-sized, length 0.30–0.44 mm. Head with short rostrum, blunt, not projected; ocellus as large as eye; lateral head pores tiny. Antennules with sensory seta about two times smaller than antennular body. Antenna with segments of endopodite presenting spinules inserted near to terminal portion, antennal formula: setae 013/003, spines 001/101, apical spines of different length, seta on the first exopodite segment not observed. Postabdomen long, distal portion presenting incision, lateral fascicles arranged in seven groups, 8–9 clusters of marginal denticles. Terminal claw about 1.5 times longer than anal margin. Basal spine about 1.2 times as long as width of terminal claw at its base and with long setules on the dorsal margin. Limb I: with ODL seta about same length as the longest IDL seta, IDL with two setae armed with strong proximal spines. Limb II: with seta on exopodite, accessory seta present on endite, scrapers 6–8 of similar length, filter comb with seven setae. Limb III: exopodite with six setae, seta 3 about 3.2 times longer than fifth seta, seta 6 about two times shorter than fifth seta, distal endite with sensillum. Limb IV: exopodite with six setae, fourth seta about 3.3 times shorter than fifth seta, third seta about 1.9 times shorter than fifth seta. Limb V: with exopodite without depression on marginal line, setae of the inner lobe of similar size, one long and inflated element inserted behind the inner setae present, filter comb absent.

Male. Postabdomen smaller than in female, postanal margin armed with many clusters of spinules, 7–8 lateral fascicles. Terminal claw short and robust. Basal spine long and sinuous. Antennules with sensory seta about 1.3 times shorter than length of antennular body; male seta about 3.7 times shorter than length of the antennules. Limb I with ODL seta about 1.5 times longer than small seta of the IDL, male seta of similar length to smaller seta of IDL.

Redescription. Adult parthenogenetic female. Habitus ( Figs. 2 A, 12A). Animal medium-sized, length 0.30– 0.44 mm, about 1.6 times as long as high.

Head ( Fig. 2 A). Ocellus as large as eye. Rostrum short, blunt, not projected. Three main head pores of similar size connected by narrow connection, IP about 1.4 times longer than PP ( Fig. 2 C–D). Lateral head pores tiny, not inserted near to main head pores, located between anterior and median pores ( Fig. 2 C). Head shield not studied.

Labrum ( Fig. 2 E). Labral keel wide in lateral view, moderately convex, naked. Apex slightly projected towards anterior (in some individuals the apex is not projected).

Carapace ( Fig. 2 A–B). Rectangular in lateral view presenting lateral compression, colorless and transparent. Carapace striate with many longitudinal lines. Ventral margin concave near to median portion, with 34–40 setae, proximal group longer than other setae, short spines present between ventral setae ( Fig. 2 B). Ventral setae followed by spinules not arranged in groups, proximalmost spinules relatively thick, projecting beyond margin ( Fig. 2 B). Posterior ventral corner without denticles. Posterior lines of valve are weakly wavy.

Antennules ( Fig. 2 F). Exceeding tip of rostrum, about two times longer than wide, three rows of setules on antennular body, distalmost row longer than others. Antennular sensory seta slender, about two times smaller than antennular body, inserted at two-thirds of the antennular length. Nine terminal aesthetascs of different sizes that do not exceed the length of the antennular body.

Antenna ( Fig. 2 G). Coxal setae of similar length, slightly setulated. Basipodite thick, with many spinules and a single spine. First exopodite segment with one row of conspicuous spinules on the terminal portion. Second exopodite segment presenting two rows of spinules, one these rows presenting long spinules (3–4). All segments of endopodite have short spinules inserted near to terminal portion. Antennal formula: spines 001/101, setae 013/003. Spine on the first segment of the endopodite naked, thick, long, exceeding the length of the second segment. Apical spines of different length, naked. Apical setae bi-segmented and densely setulated.

Thorax about two times longer than abdomen ( Fig. 2 A). Abdominal setae not studied.

Postabdomen ( Figs. 2 H–I; 12B). Long, relatively wide, about 2.6 times as long as wide, ventral margin relatively straight, ventral margin without rows of spinules. Pre-anal margin longer than anal margin and similar in length to postanal margin. Anal margin with concave portion near to pre-anal corner, armed with at least three groups of spinules. Postanal margin rounded and robust, distal portion presenting incision variable in size (intrapopulation variation), inserted near to terminal claw base. Lateral fascicles arranged in seven groups with up 15 long setules; at least four fascicles exceeding the margin of the postabdomen. Eight-nine clusters of marginal denticles presenting 2–3 denticles, proximalmost denticles may be not arranged in groups. Terminal claw ( Fig. 2 H– I). Implanted at projected basis from the postabdomen, about 1.5 times longer than anal margin, slender, uniformly curved, with one row of spinules on base. Two armed pectens; inner spinules long, laterally inserted; outer spinules decreasing in length towards distal portion. Basal spine short in relation to terminal claw, about 1.2 times as long as width of terminal claw at its base, armed with long setules on the dorsal margin.

Mandibles ( Fig. 3 A). Well developed in relation to body size. First maxilla not studied, most probably absent.

Five pairs of limbs. Limb I ( Fig. 3 B–C). Epipodite not studied. Accessory seta relatively long, plumose. ODL with thin seta, serrulated from to median portion, about same length as the longest IDL seta. IDL with three groups of spinules on its face, two setae of similar size present; setae armed with strong proximal spines, the distalmost ones as thin denticles. Third endite with four setae relatively robust; inner setae setulated (a–b), slightly longer than the other two. Second endite with two rows of strong spinules; three setae of different length (d–f), seta 5 (e) about 1.5 times longer than seta 4 (f) and about 3.2 times longer than seta 6 (d); setae 4–5 (e–f) with thick spinules on lateral face; seta 5 with spinules inserted on median portion (e); seta 6 (d) about two times shorter than seta 4. First endite with three marginal setae (g–i), setae 2–3 (h–i) bi-segmented and of similar length. No specialized elements on the endites. Ejector hooks of different length. Ventral face of the limb with seven rows of setules organized in clusters, decreasing in length towards the distal portion. Gnathobase thick, with a single densely setulated seta on its tip.

Limb II ( Fig. 3 D–E). Exopodite elongated, with tiny proximal spinules, distally setulated. Seta on exopodite present, about 1.5 times smaller than the exopodite itself. Endite armed with eight scrapers uniformly denticulated, accessory setae near to scraper 1. Scraper 3 shorter than 4; scraper 6–8 of similar length. Proximal portion of gnathobase short, wide and densely setulated; distal portion armed with three elements and one sensillum, first element with apex blunt. Filter comb armed with seven setae setulated from median portion; seta 1 setulated and remarkably shorter than other setae.

Limb III ( Fig. 3 F–H). Pre-epipodite and epipodite not studied. Exopodite quadrangular with six marginal setae arranged in 2+4; setae 1–2 of similar length; seta 3 bi-segmented, distal segment setulated, about 3.2 times longer than fifth seta; fourth seta short and thick; sixth seta setulated, about two times shorter than fifth seta; all setae are plumose. Distal endite with three setae (1’–3’), two scraper-like of similar length (1’–2’), sensillum present between them; third seta geniculated and bilaterally armed with many setules (3’). Basal endite armed with four plumose setae increasing in length towards gnathobase. Gnathobase armed with four elements, first a robust and cylindrical sensillum, second a geniculated seta setulated on the base and distally, third and fourth elements naked, with acute tip. Filter comb armed with seven long setae.

Limb IV ( Fig. 3 I). Pre-epipodite rounded and setulated, epipodite oval with short projection. Exopodite with six plumose marginal setae; setae 1–3 of similar length. Fourth seta about 3.3 times shorter than fifth seta, reaching the midle length of the sixth seta. Distal endite with four setae (1’–4’), one scraper-like (1’), three flaming-torchlike decreasing in length towards the base (2’–4’). Basal endite armed with three soft setae increasing in length towards the base. Gnathobase armed with a long and cylindrical sensillum; long seta present, inserted on a robust base. Filter comb armed with five setulated setae.

Limb V ( Fig. 3 J–K). Pre-epipodite subquadrangular and densely setulated, epipodite oval with short projection. Exopodite oval, not divided in lobes, about two times as long as wide, marginal line between setae 3–4 densely setulated; four plumose marginal setae decreasing in length. Third seta about 1.9 times shorter than first seta; fourth seta about 1.6 times shorter than third seta. Internal lobe wide, oval and with long terminal setulae; two setulated setae of similar size on inner face of the lobe; one long and inflated element inserted behind the inner setae. Gnathobase reduced, with a short element. Filter comb absent.

Male. Habitus ( Fig. 2 J). Length 0.29–0.33 mm, about 1.6 times as long as high.

Head ( Fig. 2 J). Rostrum short, blunt, not projected; ocellus and eye of similar size; main head pores of similar size, nearly connected; lateral head pores tiny, inserted on same plane as the median main pore ( Fig. 2 K). Labral keel wide, naked, with apex projected. Carapace relatively elongated, ornamentation as obscure longitudinal lines; ventral margin armed with 37 slightly plumose setae not differentiated in groups, followed by fine spinules, the most proximal are robust and exceeding the line of the posterior margin; fine spinules between ventral setae present. Posterior-ventral corner without denticles. Thorax two times longer than abdomen; two rows of abdominal setae present.

Antennules ( Fig. 2 L). Exceeding the tip of rostrum, about 1.8 times as long as wide; three rows of setules decreasing in length toward distal portion of antennular body. Nine aesthetascs of different length, shorter than length of antennular body; lateral aesthetascs not observed. Sensory seta long, about 1.3 times shorter than length of antennular body. Male seta short and robust, about 3.7 times shorter than length of the antennules, inserted at distal three-thirds.

Antenna as described for females.

Postabdomen ( Figs. 2 M, 12C). Moderately rectangular, smaller than in female, narrowing distally; anal margin shorter than postanal margin; anal angles well defined; postanal margin armed with many clusters of spinules; seven-eight lateral fascicles, distalmost ones exceeding the margin line; anal margin with spinules differentiated in three groups; gonopores opening ventrally, subapically to terminal claw. Terminal claw smaller and more robust than in female, tip acute; pecten formed by thick spinules. Basal spines long, robust and sinuous, exceeding the middle length of terminal claw; one row of fine spinules inserted on its base.

Limb I ( Fig. 3 L). Smaller than in female, copulatory hook U-shaped. Copulatory brush present; seta of the copulatory brush not studied. Seta of the ODL long, slightly serrulated, about 1.5 times longer than the smallest IDL seta. IDL with two setae of different length with strong proximal spines; male seta relatively long, similar in length to the smallest IDL seta.

Ephippial female. Unknown.

Differential diagnosis. Coronatella poppei was entirely revised and can now be differentiated from other species of the genus because it has long and robust postabdomen with 8–9 clusters of marginal denticles, seta on ODL relatively short in the females and the limb II with accessory seta near first scraper. The male of C. poppei has a long and sinuous basal spine in postabdominal claw similar to the one observed in C. circumfimbriata male ( Sinev 2009), but it presents more evident sinuosity. The main differences between C. poppei , C. rectangula and the species here described from Brazil are summarized in Table 1.

Distribution and biology. Coronatella poppei was found in two locations in South America, Limache, Chile (type location) and Lagoa dos Patos, Rio Grande do Sul state, Brazil. Initially, our data indicate that this species occurs in the Neotropical region (as discussed in Van Damme & Dumont 2008b), possibly restricted to the southern portion of South America, including high altitude regions ( Fig. 13 ). The biology of this species is not known and more studies concerning its ecology are necessary.

Figures

FIGURE 2. Coronatella poppei (Richard, 1897) from Limache, Chile. A – I parthenogenetic female. A, habitus, lateral view. B, posteroventral corner of carapace. C – D, head pores. E, labral keel. F, antennule. G, antenna. H – I, postabdomen. J – M Male. J, habitus. K, head pores. L, antennule. M, postabdomen. scale bars = 100 µm.

FIGURE 3. Coronatella poppei (Richard, 1897) from Limache, Chile. A, mandibles, B, limb I. C, idem — ODL and IDL. D, limb II. E, idem — exopodite. F, limb III. G, idem — setae 5 and 6 of the exopodite. H, idem — endite, arrow showing the sensillum. I, limb IV. J, limb V, arrow showing the element. K, idem — internal lobe. L, limb I of the male. For abbreviations, see Material and methods. Scale bars = 50 µm.

FIGURE 13. Geographical distribution of Coronatella species in the Neotropics. Specifically for Brazil, the map presents the delimitation of hydrographic Regions according to Resoltution 32 from Conselho Nacional de Recursos Hídricos. 1 Amazônica; 2 Tocantins / Araguaia; 3 Atlântico Nordeste Ocidental; 4 Parnaíba; 5 Nordeste oriental; 6 Paraguai; 7 São Francisco; 8 Atlântico leste; 9 Paraná; 10 Uruguai; 11 Atlântico sul; 12 Atlântico sudeste. Coronatella monacantha is widely distributed in the Neotropics. Coronatella poppei seems to be restricted to the meridional part of South America. Coronatella paulinae sp. nov., until this moment, shows distribution in the central part of Brazil. Coronatella serratalhadensis sp. nov. and C. undata sp. nov. occur in the Brazilian Northeast; however, C. undata sp. nov. seems to be restricted to environments closer to the coast.