Coronatella paulinae, Sousa, Francisco Diogo Rocha, Elmoor-Loureiro, Lourdes Maria Abdu & Santos, Sandro, 2015

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 : 219-224

Coronatella paulinae sp. nov.

( Figs. 4–6 ; 12)

Coronatella poppei in Sousa & Elmoor-Loureiro (2012), p. 357.

Etymology. The name “ paulinae ” refers to the renowned Brazilian limnologist, Paulina Maria Maia Barbosa , who provided the specimens selected as type series in this taxonomic revision.

Type Locality. Gambazinho Pond, Rio Doce State Park, Minas Gerais, Brazil (19°47'10.6"S, 42° 34' 48.3"W).

Type Material. Holotype. Undissected, adult parthenogenetic female in tube with 90% ethanol deposited at the Museum of Zoology of the University of São Paulo under access number MZUSP 32923. The label of the holotype is: “ Coronatella paulinae sp. n., 1 parth. ♀ from to Gambazinho pond, Rio Doce State Park, Minas Gerais, Brazil. Holotype ”.

Paratypes. One undissected adult parthenogenetic female deposited at the Museum of Zoology of the University of São Paulo under access number MZUSP 32924. Several females and eight males deposited at Lourdes M.A. Elmoor-Loureiro’s collection (EL02330). Sixteen females and eight slides containing dissected specimens deposited at Laboratório de Biodiversidade Aquática, Universidade Católica de Brasília ( CLLA 042 to CLLA 049).

Material Examined. Twelve adult parthenogenetic females from Gambazinho pond, Rio Doce State Park, Minas Gerais, Brazil (19°47'10.6"S, 42° 34' 48.3"W), collected by Paulina M. Maia-Barbosa on 18.vi.2011. One adult parthenogenetic female from the Paranoá Lake, Distrito Federal, Brazil (15° 45' 18"S, 47° 49' 12"W), collected by Lourdes M. A. Elmoor-Loureiro on 17.ix.1983. Two adult parthenogenetic females from the São Bartolomeu River, Distrito Federal, Brazil (15° 41' 01.2"S, 47° 39' 43.9"W), collected by GEEA on 11.viii.2006 and 29.viii.2006.

Diagnosis. Female. Animal small-sized, length 0.29–0.33 mm. Head with rostrum relatively long, blunt, projected downward, ocellus as large as eye, lateral head pores tiny. Carapace with dorsal keel, presenting lateral compression, with at least 13 longitudinal lines, 28–33 ventral setae not reaching the end of the carapace, posterior ventral corner without denticles. Antennules with sensory seta about 1.8 times smaller than antennular body. Antenna with first exopodite segment presenting one row of long setules on the base, antennal formula: spines 001/ 101, setae 113/003, apical spines of different lengths. Postabdomen long, narrowing distally, anal margin very concave, lateral fascicles arranged in 5–6 groups, 5–6 clusters of marginal denticles. Terminal claw about 1.6 times longer than anal margin. Basal spine about two times as long as terminal claw width at its base and with long setules on the dorsal margin. Limb I with ODL seta about same length as the longest IDL seta; accessory seta relatively short; IDL with two setae armed with short proximal spines. Limb II without seta on exopodite; scrapers 6–8 of similar length and armed with strong denticles; filter comb with six setae. Limb III: exopodite with six setae; seta 3 about 2.9 times longer than fifth seta; seta 6 about 1.6 times shorter than fifth seta. Limb IV: exopodite with six setae; fourth seta about 2.7 times shorter than fifth seta; third seta about 1.9 times shorter than fifth seta. Limb V with exopodite with depression on marginal line; first seta of exopodite long; setae of inner lobe of different size; one long and inflated element inserted behind the inner setae present; filter comb present. Male. Unknown.

Description. Parthenogenetic female. Habitus ( Figs. 4 A, C; 5A; 12D). Animal small-sized, length 0.29–0.33 mm, about 1.5 times as long as high.

Head ( Fig. 4 A). Ocellus as large as eye. Head shield about 1.9 times as long as wide, posterior margin line irregular ( Fig. 4 E). Rostrum relatively long, blunt, projected downward ( Fig. 4 E–5D). Three main head pores connected by narrow connection, median pore smaller than proximal and distal pores ones ( Fig. 4 E–G), IP about 2.2 times longer than PP ( Fig. 4 E–G). Lateral head pores tiny, inserted at same level as the median pores, distance to main head pores about 2.5 times shorter than the distance to line of the head shield.

Labrum ( Fig. 4 H–I; 5C). Labral keel wide in lateral view, relatively short, naked; anterior portion convex, apex slightly projected. Base presenting fine spinules.

Carapace ( Figs. 4 A–B; 5A–B). Oval and narrowing in lateral view presenting lateral compression, colorless and transparent. Carapace striated with at least 13 longitudinal lines. Dorsal keel present ( Fig. 4 C). Ventral margin slightly concave near to last third of carapace length, with 28–33 setae, proximal and distal groups longer than median group ( Fig. 4 B), short spines present between ventral setae; ventral setae not reaching the end of the carapace, followed by spinules not arranged in groups and not exceeding the margin ( Fig. 4 D). Posterior ventral corner without denticles. Posterior lines of valve with distinct waves.

Antennules ( Fig. 4 J–K). Exceeding tip of rostrum, about 2.7 times longer than wide, three rows of setulae of similar length on antennular body. Antennular sensory seta slender, about 1.8 times smaller than antennular body, inserted at two-thirds of antennular length. Nine terminal aesthetascs of different sizes not exceeding the length of the antennular body.

Antenna ( Fig. 4 L–M; 5C). Coxal setae not studied. Basipodite thick, with many spinules and one long spine. First exopodite segment robust, with one row of long setulae on the base; apical spinules short. Second exopodite segment presenting one row of setulae near terminal portion. First endopodite segment with one row of setulae relatively long. Second endopodite segment presenting one row of fine and short spinules on terminal portion. Third segment of the exo and endopodite naked. Antennal formula: spines 001/101, setae 113/003. Seta on the first exopodite segment relatively long, about 0.75 the length of the second segment seta; setae on second segment bisegmented, distal segment plumose. Spine on the first endopodite segment thin, long, exceeding the length of the second segment. Apical spines of different length, naked. Apical setae bi-segmented and plumose on distal segment.

Postabdomen ( Figs. 2 H–I; 12B). Long, about 1.6 times as long as wide, ventral margin relatively curved. Rows of the spinules were not observed on the ventral margin. Pre-anal margin longer than anal margin and similar in length to postanal margin. Anal margin clearly concave, armed with at least three groups of spinules; angles evident; 2–4 fascicles present. Postanal margin slightly rounded, narrowing distally; distalmost margin with variable shape; lateral fascicles arranged in 5–6 groups with 9–12 long setulae exceeding the margin of the postabdomen; 5–6 groups of marginal denticles, proximalmost denticles not clustered, the distalmost clustered.

Terminal claw ( Fig. 5 F). About 1.6 times longer than anal margin, slender, with four-5 spinules on the base, and implanted at a projected basis from the postabdomen. Two pecten present; inner spinules long, laterally inserted; outer spinules of similar length. Basal spine projected on the terminal claw, relatively long and slender, about two times as long as width of terminal claw at its base, armed with long setules on the dorsal margin.

Mandibles ( Fig. 4 R). Well developed in relation to body size.

First maxilla ( Fig. 6 A). Well developed, with two setulated setae.

Five pairs of limbs.

Limb I ( Fig. 6 B–D). Epipodite with long projection. ODL with thin seta, serrulated from to median portion of seta, about the same length as the longest IDL seta; accessory seta relatively short, plumose. IDL with two groups of spinules on its face, two setae of different size present; longest seta armed with strong and relatively short proximal spines, grouped at distal third of the seta; distalmost spines as thin denticles; shortest seta armed with strong and relatively short proximal spines. Third endite with four setae; inner setae setulate (a–b), shorter than the other two. Second endite with two rows of strong spinules; three setae of different length (d–f), seta 5 (e) about 1.2 times longer than seta 4 (f) and about 2.6 times longer than seta 6 (d); setae 4–5 (e–f) with thick spinules on lateral face; seta 5 (e) with spinules inserted on median portion; seta 6 (d) about 2.1 times shorter than seta 4 (f). First endite with three marginal setae (g–i), two bi-segmented (g–h); setae 1–3 (g–i) of similar length. No specialized elements on endites. Ejector hooks of different length. Ventral face of limb with seven rows of setules organized in clusters, decreasing in length toward distal portion. Gnathobase thick, with distal portion densely setulated.

Limb II ( Fig. 3 D–E). Exopodite elongated, with long distal spinules and short spinules on basal region; seta on exopodite absent. Endite armed with eight scrapers; accessory seta absent. Scraper 1–2 of similar length, longer than scraper 3; scraper 4 of similar length to scraper 3 and longer than scraper 5; scrapers 6–8 short, of similar length; scrapers with strong denticulation, except scrapers 1 and 2, which are finely denticulated; denticulation on scrapers 5–8 stronger than on scrapers 3–4. Proximal portion of gnathobase wide and densely setulated; distal portion armed with three elements and one sensillum, first element as a short seta. Filter comb armed with six setae setulated from median portion; seta 1 remarkably shorter than the others, densely setulated.

Limb III ( Fig. 6 H–I). Pre-epipodite not studied. Epipodite oval with short projection. Exopodite subquadrangular with six marginal setae arranged in 2+4; setae 1–2 of similar length; seta 3 bi-segmented, armed with short setules, about 2.9 times longer than fifth seta; fourth seta long and plumose, about 2.4 times shorter than third seta and 1.2 times longer than fifth seta; sixth seta slightly setulated, about 1.6 times shorter than fifth seta. Distal endite with three setae (1’–3’), two scraper-like of similar length (1’–2’), without element between them; third seta slightly geniculated and bilaterally armed with many setules (3’). Basal endite armed with four setulated setae increasing in length towards the gnathobase; four soft setae increasing in length toward base. Gnathobase armed with four elements, first a robust and bottle-shaped sensillum, second a geniculated seta with a group of setules on its base and distally setulated, third and fourth elements naked, with acute tip. Filter comb armed with seven long setae slightly setulated from median portion.

Limb IV ( Fig. 6 J–K). Pre-epipodite subquadrangular and densely setulated. Epipodite subquadrangular with long projection. Exopodite rounded with six marginal setae: setae 1–4 plumose; setae 1–2 of similar length; third seta about 1.3 times shorter than setae 1–2; fourth seta short, about 2.7 times shorter than third seta and about 1.9 times shorter than fifth seta; fifth seta slightly setulated; sixth seta slightly setulated, about 1.2 times shorter than fifth seta. Distal endite with four setae (1’–4’), one scraper-like (1’), three flaming-torch-like decreasing in length towards the base (2’–4’). Basal endite armed with three soft setae increasing in length towards the base. Gnathobase armed with one long sensillum, of similar length to median flaming torch; long seta inserted on robust base. Filter comb armed with five setae setulated from median portion.

Limb V ( Fig. 6 L–M). Pre-epipodite subquadrangular and densely setulated, epipodite oval with long projection. Exopodite wide, not divided in lobes, about twice as long as wide, marginal line between setae 3–4 presenting a slight and densely setulated depression. Four plumose marginal setae decreasing in length: first seta long, about 1.5 times longer than second seta; second seta about 1.5 times longer than third seta; fourth seta short, about two times shorter than third seta. Internal lobe wide, oval and with long terminal setules: two setulated setae of different size on its inner face; one long and inflated element inserted behind of the inner setae. Gnathobase reduced. Filter comb with one seta.

Adult Male. Unknown.

Ephippial female. Unknown.

Differential diagnosis. Coronatella paulinae sp.nov. is distinguished from other species of the genus because of its well-developed dorsal keel. Regarding Brazilian Coronatella species, C. paulinae sp.nov. differs from other species possessing a postabdomen that narrows towards the distal portion and anal margin very concave, row of ventral setae not reaching the end of the carapace, absence of setae on the exopodite of Limb II and presence of a seta on the filter comb of Limb V. Coronatella paulinae sp.nov. resembles the Palearctic C. cf. trachistriata Chen, Zhang & Liu, 1994 in external morphology, presence of the denticles on the IDL setae, shape of postabdomen and rostrum (see Kotov et al. 2011). However, C. paulinae sp.nov. differs from C. cf. trachistriata in the presence of a dorsal keel, smaller number of marginal denticles on postabdomen, seta on the first exopodite antennal segment and filter comb on Limb V. The main differences between C. paulinae sp.nov, C. rectangula and other Brazilian species of the genus may be observed in Table 1.

Distribution and biology. Coronatella paulinae sp.nov. was found in two different hydrographic regions of Brazil (Paraná and São Francisco basins), in both lentic and lotic systems, always associated with some kind of substrate. We believe that after C. monacantha , C. paulinae sp.nov. is the Coronatella species with the broadest distribution in Brazil ( Fig. 13 ).

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 4. Coronatella paulinae sp. nov.. A, habitus, lateral view. B, carapace. C, Habitus, frontal view. D, posteroventral corner of carapace. E, head Shield. F, head pores. G. idem. H, labral keel. I, idem. J, antennule. K, idem. L, antenna. M, idem. N, postabdomen. O – Q, idem — distalmost portion. Scale bars = 100 µm.

FIGURE 5. Coronatella paulinae sp. nov.. Scanning Electronic Microscopy. A, habitus. B, longitudinal lines on the carapace. C, antenna and labral keel. D, rostrum. E, postabdomen—distalmost portion. F, terminal Claw. Scale bars = 10 µm.

FIGURE 6. Coronatella paulinae sp. nov.. A, maxillule. B, limb I. C, idem — epipodite. D, idem — ODL and IDL. E, limb II. F, idem — exopodite. G, idem — gnathobase. H, limb III, exopodite. I, idem - endite. J, limb IV, exopodite. K, idem — endite. L, limb V, arrow showing one element and filter comb seta. M, idem — internal lobe. 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.