Coronatella undata, 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 : 229-233

Coronatella undata sp.nov.

( Figs. 9–10 , 12 )

Alona sp. in Sousa et al. (2009), p. 103.

Etymology. The name “ undata ” (from the latin “ unda ”) refers to the marked waves observed on the posterior marginal line of the carapace.

Type locality. Swamp on Ypioca farm, São Gonçalo do Amarante, Ceará, Brazil (3°34’39”S, 38°52’31”W).

Type material. Holotype. 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 32974. The label of the holotype is: “ Coronatella undata sp. n., 1 parth. ♀ from to Swamp of the Fazenda Ypioca, São Gonçalo do Amarante, Ceará, Brazil. Holotype ”.

Paratype. One undissected adult parthenogenetic female deposited at the Museum of Zoology of the University of São Paulo under access number MZUSP 32975. Paratypes. Eleven females and three slides containing dissected individuals deposited at Laboratório de Biodiversidade Aquática, Universidade Católica de Brasília ( CLLA 042 to CLLA 049). Material collected by Maria Beatriz Gomez e Souza on 19.xii.2007.

Other Material Examined. One adult parthenogenetic female from the Esperança pond, Lençóis Maranhenses National Park Maranhão, Brazil (2°40’ 51”S, 43°1’55”W), material collected on 01.vii.2000, leg. Maria José Saraiva Lopes (EL02125).

Diagnosis. Female. Animal small-sized, length 0.24–0.36 mm. Head with rostrum short, blunt, projected downward, ocellus as shorter as eye, lateral head pores tiny. Labral keel short, naked, marginal line wavy. Carapace with dorsal keel, presenting weak lateral compression, arched anteriorly, with ten-12 longitudinal lines, 34–38 ventral setae of similar length, posterior ventral corner with two denticles, posterior margin of valves strongly wavy. Antennules with sensory seta about 2.8 times smaller than antennular body. Antenna with second exopodite segment presenting one row of long setules, antennal formula: spines 001/101, setae 113/003, apical spines of similar length. Postabdomen relatively short, lateral fascicles arranged in four groups exceeding the marginal line, five-6 clusters of marginal denticles, projection for insertion of terminal claw presenting one small incision. Terminal claw about 1.5 times longer than anal margin and with one row of short spinules on base. Basal spine about 2.5 times as long as width of terminal claw at its base and with setulae on the dorsal margin. Limb I with ODL seta shorter than longest IDL seta; IDL with two setae armed with long and strong proximal spines, first endite with first seta short. Limb II with rudimentary seta on exopodite, scraper 8 remarkably short, filter comb with six setae. Limb III: exopodite with six setae; seta 3 about 4.2 times longer than fifth seta; seta 6 naked and longer than midlength of the fifth seta. Limb IV: exopodite with six setae; fourth seta about 1.8 times shorter than fifth seta; sixth seta naked and about 1.3 times shorter than fifth seta; distal endite with thick first flaming-torch. Limb V with exopodite with depression on marginal line, setae of inner lobe of similar size, gnathobase setulated and armed with one short element, filter comb absent. Male. Unknown.

Description. Parthenogenetic female. Habitus ( Fig. 9 A; 12J). Animal small-sized, length 0.24–0.36 mm, about 1.5 time as long as hihgh.

Head ( Fig. 9 A). Ocellus shorter than eye. Rostrum short, blunt, projected downward. Three main head pores connected by narrow connection, IP about 1.4 times longer than PP; median pore smaller than posterior and anterior pores ( Fig. 9 D–F); lateral head pores tiny, inserted nearer main head pores than marginal line of head shield ( Fig. 9 D–F). Head shield ( Fig. 9 F). With anterior margin rounded, mandibular articulation inserted at posterior portion.

Labrum ( Fig. 9 G–H; 12K). Labral keel relatively short, naked; with a wavy marginal line. Apex rounded, not projected.

Carapace ( Fig. 9 A–C; 12L) presenting weak lateral compression, arched anteriorly, colorless and transparent; dorsal keel absent; carapace striated with 10–12 longitudinal lines; ventral margin slightly concave near to posterior portion, with 34–38 setae not differentiated in groups; short spinules present between ventral setae; ventral setae followed by spinules not arranged in groups, proximalmost projected beyond carapace margin. Posterior ventral corner with two denticles. Posterior margin of the valve strongly wavy ( Fig. 9 B–C).

Antennules ( Fig. 9 I) long, exceeding the tip of rostrum, about 2.5 times longer than wide; three rows of setulae of similar length on antennular body. Antennular sensory seta short, about 2.8 times smaller than antennular body, inserted at two-thirds of antennular length. Nine terminal aesthetascs of different size that do not exceed the length of the antennular body.

Antenna ( Fig. 9 J). Coxal setae of similar length. Basipodite thick, with one spine. First exopodite segment with short setulae near to base. Second exopodite segment presenting a group of three relatively long setulae and inserted on terminal portion of segment. Antennal formula: spine 001/101; setae 113/003. Seta on the first exopodite segment short, remarkably exceeding the length of the last segment; seta on the second segment bisegmented and densely setulated. Spine on the first segment of the endopodite thick, long, exceeding the length of the second segment but not reaching the midlength of the third segment. Apical spines of similar size. Apical setae bi-segmented.

Thorax about two times longer than abdomen ( Fig. 9 A). Abdominal setae not studied.

Postabdomen ( Fig. 9 K–M) short, about 2.8 times as long as wide; ventral margin relatively straight. Rows of the spinules were not observed on the ventral margin. Preanal margin longer than anal and postanal margin. Anal margin concave near to preanal corner, armed with at least three groups of spinules; short lateral fascicles; postanal corner not evident. Postanal margin rounded and robust; projection for insertion of terminal claw presenting one small incision ( Fig. 9 M); lateral fascicles arranged in four groups with variable number of setules; all fascicles exceeding the margin of the postabdomen; five-six clusters of marginal denticles, distal denticles may be not clustered. Postabdominal seta ( Fig. 9 K) about midlength of postabdomen, distal portion setulated. Terminal claw ( Fig. 9 K–L) about 1.5 times longer than anal margin, thick, uniformly curved, with one row of short spinules on base, implanted at a projected basis from the postabdomen. Pecten armed with two groups of spinules; inner spinules long and laterally inserted to terminal claw. Basal spine long in comparison to terminal claw, inserted in its base, about 2.5 times as long as width of terminal claw at its base, armed with setules on the dorsal margin.

Mandibles ( Fig. 9 N). Well developed in relation to body size, molar surface with robust denticles.

First maxilla not found.

Five pairs of limbs.

Limb I ( Fig. 10 A–C). Epipodite not studied. ODL with thin seta, serrulated from the median portion, remarkably shorter than longest IDL seta; accessory seta not studied. IDL with two groups of spinules on its face, two setae of different size present; setae armed with long and strong proximal spines, distalmost spines as thin denticles. Third endite with four setae relatively robust; inner setae setulated (a–b), similar in length to the other two setae. Second endite with two rows of strong spinules; three setae of different length (d–f); seta 4 (f) long, about the same length as seta 5 (e); setae 4–5 (e–f) with thick spinules on lateral face; seta 6 (d) about two times shorter than seta 4 (f). First endite with three marginal setae (g–i), setae 2–3 (g–h) bi-segmented and of similar length, first seta (i) short. No specialized elements on endites. Ejector hooks of similar size. Ventral face of limb with six rows of setules, decreasing in length towards the distal portion. Gnathobase not studied.

Limb II ( Fig. 10 D–E). Exopodite elongated, distally setulated. Seta on exopodite rudimentary. Endite armed with eight scrapers decreasing in length towards gnathobase, without accessory seta near scraper 1; scraper 3 shorter than scrapers 1–2 and longer than scraper 4; scraper 5 shorter than scraper 4; scraper 8 remarkably shorter than scrapers 6–7; scrapers 3, 5–7 armed with thick denticles. Proximal portion of the gnathobase long and densely setulated; distal portion armed with three elements and one sensillum; first element with blunt apex. Filter comb armed with six setae setulated from median portion; seta 1 remarkably shorter than other setae.

Limb III ( Fig. 10 F–G). Pre-epipodite and epipodite not studied. Exopodite subquadrangular with six marginal setae arranged in 2+4; setae 1–2 of different length; seta 3 long, bi-segmented, setulated, about 4.2 times longer than fifth seta; fourth setae about 3.1 times shorter than third seta and 1.3 times shorter than fifth seta; sixth seta naked, longer than midlength of the fifth seta. Distal endite with three setae (1’–3’), two scraper-like of similar length (1’–2’); third seta slightly geniculated and armed bilaterally with many setules (3’). Basal endite armed with four plumose setae slightly increasing in length towards the gnathobase; four soft setae increasing in length towards the gnathobase. Gnathobase armed with four elements, first a robust and cylindrical sensillum, second a geniculated seta with a group of setulae on its base and distally setulated, third and fourth elements naked, with acute tips. Filter comb armed with seven long setae.

Limb IV ( Fig. 10 H). Pre-epipodite rectangular and densely setulated, epipodite oval with long projection. Exopodite rounded with marginal setae: setae 1 about 1.2 times longer than seta 2; seta 3 about 1.2 times longer than seta 1 and 1.5 times longer than seta 2; fourth seta about 1.8 times shorter than fifth seta and reaching midlength of the sixth seta; sixth seta naked, 1.3 times shorter than fifth seta. Distal endite with four setae (1’–4’): one scraper-like (1’) and three flaming-torch-like decreasing in length towards the base (2’–4’); first flaming-torch thick, similar in length to scraper-like seta; endite armed with one row of setulae near scraper-like seta. Basal endite armed with three soft setae increasing in length towards the base. Gnathobase armed with one long, thin and cylindrical sensillum, and a long seta inserted on a robust and naked base. Filter comb armed with five setulated setae.

Limb V ( Fig. 10 I). Pre-epipodite oval and densely setulated, epipodite oval with long projection. Exopodite oval, not divided in lobes, about twice as long as wide; marginal line between setae 3–4 with a densely setulated depression; four plumose marginal setae decreasing in length; third seta about 1.5 times shorter than first seta; fourth seta about 1.8 times shorter than third seta. Internal lobe wide, oval and with long terminal setules; two setulated setae of similar size on the inner face of the lobe, without any element between them. Gnathobase reduced, with one short element, setules present. Filter comb absent.

Adult male. Unknown.

Ephippial female. Unknown.

Differential diagnosis. Coronatella undata sp. nov. is differentiated from the other species of the genus by a combination of following morphological traits: (1) denticles on the labral keel absent, (2) presence of two denticles on the posteroventral corner of the carapace, (3) ventral setae of the carapace not arranged in groups and (4) marked waves on the posterior marginal line of carapace. Coronatella undata sp. nov. resembles C. monacantha but differs regarding the fine features of the thoracic limbs, such as rudimentary seta on the exopodite of Limb II. More differences between these species are presented in Table 1.

Distribution and biology. Coronatella undata sp.nov. is known for only two localities, the Ypioca farm swamp, in São Gonçalo do Amarante, Ceará state and the Esperança pond at the Lençóis Maranhenses National Park, Maranhão state, Brazil ( Fig. 13 ). We believe that this species is distributed in coastal habitats.

Figures

FIGURE 9. Coronatella undata sp. nov.. A, habitus. B, posteroventral corner of carapace. C, idem. D, head pores. E, idem. F, head shield. G – H, labral keel. I, antennule. J, antenna. K, postabdomen. L, idem. M, idem — arrow showing incision on the projection for the inserting of claw. N, mandibles. Scale bars = 100 µm.

FIGURE 10. Coronatella undata sp. nov.. A, limb I. B – C, idem — ODL and IDL. D, limb II. E, idem—arrow showing the rudimentary seta on the exopodite. F, limb III. G, idem—gnathobase. H, limb IV, arrow showing the most robust flaming-torch satae. I, limb V. For abbreviations, see Material and methods. Scale bars = 50 µm.

FIGURE 12. Coronatella species with occurrence in Brazil. A, Coronatella poppei. B, idem — postabdomen. C, idem — terminal claw of male. D, Coronatella paulinae sp. nov.. E, idem — postabdomen. F, Coronatella serratalhadensis sp. nov.. G, idem — posteroventral corner of carapace, arrows showing the internal group of spinules. H, idem — postabdomen. I, idem — terminal claw. J, Coronatella undata sp. nov.. K, idem — rostrum and labral keel. L, idem — posteroventral corner of carapace, arrow showing the denticles. Scale bars: 50 µm = B, C, G, I, E; 100 µm = A, D, F, H, J, K, L.

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.