Cypricercus alfredo, Almeida & Ferreira & Higuti & Martens, 2021

Almeida, Nadiny Martins De, Ferreira, Vitor Góis, Higuti, Janet & Martens, Koen, 2021, On two new species of Cypricercus Sars, 1895 (Crustacea, Ostracoda) from Brazil with a discussion on the taxonomy of the genus, Zootaxa 4938 (5), pp. 501-536 : 504-522

Cypricercus alfredo sp. nov.

( Figs. 1 , 3–14 )

2007 Cypricercus centrura —Higuti et al.: 1934, table 2.

2009 Cypricercus centrura —Higuti et al.: 664, table 1.

2010 Cypricercus centrura —Mormul et al.: 190, fig. 4.

2010 Cypricercus centrura —Higuti et al.: 267, 270, tables 2, 5.

2015a Cypricercus centrura —Matsuda et al.: 326, table 1.

2015b Cypricercus centrura —Matsuda et al.: 118, 123, table 1, fig. 5.

2016 Cypricercus centrura —Higuti & Martens: appendix 1.

2017 Cypricercus centrura —Pereira et al.: 327, 329, table 2, fig. 5.

2017 Cypricercus centrura —Higuti et al.: 7, table 2, fig. 6.

2017 Cypricercus centrura —Conceiç„o et al.: 329, table 2.

2017 Cypricercus centrura —Campos et al.: 38, table 2.

2018 Cypricercus centrura —Conceiç„o et al.: 184, table 3.

2018 Cypricercus centrura —Campos et al.: 6, table 2.

2019 Cypricercus centrura —Campos et al.: 375, table 1.

2020 Cypricercus centrurus —Conceiç„o et al.: 8, 15, table 2, fig. 4.

2020 Cypricercus sp. nov. —Higuti et al.: 2, table S1.

2020a Cypricercus sp. nov. —Rosa et al.: table 1.

2020b Cypricercus sp. nov. —Rosa et al.: 5, table 1.

Diagnosis. Cp elongated, with LV overlapping RV; with spine on the posterior margin of the RV. A2 with natatory setae not reaching beyond the tips of the claws. CR slender, its attachment with Triebel’s loop situated in the main branch. Male prehensile palps asymmetrical, Rpp with first segment slender, two apical spines and second segment with subtriangular lobe; Lpp with first segment broad, two apical spines and second segment sickle shaped. Hemipenis with ms ventrally rounded, ventral lobe of ls small, with distal margins long and bluntly pointed.

Type locality. Xambrê Lake ( PAR 1353 ), in Eichhornia crassipes . Coordinates: 23° 51’ 20.8” S, 54° 00’ 11.8” W .

Type material. Holotype: A male, with soft parts dissected in glycerine in a sealed slide and with valves stored dry in a micropalaeontogical slide ( MZUSP 41505 ).

Allotype: A female, dissected and stored as the holotype ( MZUSP 41506 ).

Paratypes: Four males dissected and stored as the holotype ( MZUSP 41507 , MZUSP 41508 , MZUSP 41509 , MZUSP 41510 ) and three male carapaces stored dry in micropalaeontogical slides ( MZUSP 41511 , MZUSP 41512 , MZUSP 41513 ) .

Two females dissected and stored as the holotype ( MZUSP 41514 , MZUSP 41515 ) and three female carapaces stored dry in micropalaeontogical slides ( MZUSP 41516 , MZUSP 41517 , MZUSP 41518 ) .

Etymology. The present species is named after Alfredo Soares da Silva (Nupélia, Universidade Estadual de Maringá, Porto Rico, Brazil), in recognition of his vast knowledge of the ever-changing biotopes of the Upper Paraná River floodplain, and his continued technical assistance in the collections of ostracods, especially in the river-floodplain system of the Upper Paraná River.

Other material illustrated. River-floodplain system of the Upper Paraná River : Three males dissected ( MZUSP 41527 ( PAR90 ), MZUSP 41528 ( PAR1184 ), MZUSP 41529 ( PAR122 )) and stored as the holotype, one male dissected ( MZUSP 41530 ( PAR823 )) and stored as the holotype ( RV lost) ( Fig. 8 ). One male dissected ( MZUSP 41519 ( PAR122 )) and stored as the holotype (soft part and RV lost), and three male carapaces stored dry in micropalaeontogical slides ( MZUSP 41520 , MZUSP 41521 , MZUSP 41522 ( PAR122 )), one female dissected ( MZUSP 41523 ( PAR122 )) and valves stored as the holotype (soft part lost), and three female carapaces stored dry in micropalaeontogical slides ( MZUSP 41524 , MZUSP 41525 , MZUSP 41526 ( PAR122 )) ( Fig. 11 ). One male dissected ( MZUSP 41531 ( PAR1426 )) and stored as the holotype, and two females dissected ( MZUSP 41532 ( PAR1426 ), MZUSP 41533 ( PAR879 )) and stored as the holotype ( Fig. 12 ) .

Araguaia River floodplain: One female dissected ( MZUSP 41534 ( ARA39 )) and stored as the holotype, and three female carapaces stored dry in micropalaeontogical slides ( MZUSP 41535 , MZUSP 41536 , MZUSP 41537 ( ARA39 )) ( Fig. 13 A–E) .

Amazon River floodplain: One female dissected ( MZUSP 41538 ( AMA40 )) and stored as the holotype ( RV lost), and three female carapaces stored dry in micropalaeontogical slides ( MZUSP 41539 , MZUSP 41540 , MZUSP 41541 ( AMA40 )) ( Fig. 13 F–J) .

South Matogrossense Pantanal : One female dissected ( MZUSP 41542 ( PAN102 )) and stored as the holotype, and three female carapaces stored dry in micropalaeontogical slides ( MZUSP 41543 , MZUSP 41544 , MZUSP 41545 ( PAN102 )) ( Fig. 14 ) .

Measurements of illustrated specimens. See Table 1.

Description of male. Valves ( Fig. 3A, B ) elongated, with greatest height situated just behind anterior margin.

Both valves with anterior calcified inner lamellae wider than posterior ones; anterior inner margins not running parallel to valve margins. LVi ( Fig. 3A, C, D ) with an inner groove running parallel to the ventral, anterior and posterior valve margins, disappearing at the dorsal side. RVi ( Fig. 3B, E, F ) without an inner groove running parallel to the ventral margins, posterior margin ( Fig. 3F ) carrying a prominent spine.

CpRl ( Fig. 3G ) LV overlapping RV along anterior margin; surface sparsely set with setae, some emerging from rimmed pores, and with small pustules ( Fig. 3J ). CpD ( Fig. 3H ) and CpV ( Fig. 3I ) with greatest width (about half of the length) situated in the middle; in dorsal view ( Fig. 3H ), anterior margin of LV with a prominent outer list, RV without such an anterior outer list.

A1 ( Fig. 4A ) with seven segments. First segment large, dorsally with one short subapical seta and ventrally with two long apical setae; Wouter’s organ not seen. Second segment subquadrate, wider than long, with one short dorsal seta and ventrally with a small Rome organ (R in Fig. 4A ). Third segment about three times longer than wide, with two apical setae, dorsal one longer, reaching beyond the tip of the fourth segment; ventral one shorter, reaching 2/3 of length of fourth segment. Fourth segment with two long dorso-apical setae and two short ventro-apical setae. Fifth segment with three long and one short setae (the latter almost reaching the tip of the terminal segment). Sixth segment with four long apical setae. Terminal segment with one short aesthetasc ya, two long and one short setae, the latter about half the length of aesthetasc ya.

A2 ( Fig. 4B, C ) with protopodite, exopodite and three-segmented endopodite. Protopodite with three ventral setae (two short and one long and hirsute, reaching beyond the middle of third segment); exopodite reduced to a small plate, with two short and one long setae. First endopodal segment with one ventral aesthetasc Y, one long apical seta (reaching the end of terminal segment) and six hirsute, natatory setae: five long, but not reaching the tips of the apical claws and one short seta with length about 1/3 of the second endopodal segment. Second endopodal segment undivided, dorsally with one long hirsute and one short hirsute seta, ventrally with four t-setae (three long but unequal hirsute setae and one short hirsute seta); apically with three claws (z1, G1, G2), three setae (z2, z3, G3) and one short y2. Terminal segment ( Fig. 4C ) with two claws (one long GM, one short Gm), aesthetasc y3 (fused with accompanying seta over short distance only) and a fine g-seta (shorter than aesthetasc y3).

Rake-like organ ( Fig. 4E ) stout, solid, T-shape, with eight apical teeth of varying size.

Md-palp ( Fig. 5C, D ) with four segments. First segment with two long and plumose setae s1 and s2 (only s1 fully illustrated here), one long and smooth seta and one short and smooth α-seta. Second segment dorsally with one group of three apical setae, two long and one short (about half the length of the long setae); ventrally with one hirsute β-seta and four hirsute unequal but long setae. Penultimate segment with three groups of setae, dorsally with four setae (unequally long, and smooth), laterally with hirsute and stout apical γ-seta, three subapical smooth setae; ventrally with one long and one short setae (the latter half the length of terminal segment). Terminal segment apically with three claws and three setae.

Md-coxa ( Fig. 5B ) elongated with apical and strong teeth, interspaced with some setae, and dorsally with one subapical seta.

Mx1 ( Fig. 4D , 5A ) with a basal (basipodite) part carrying a large branchial plate, three endites, and a two-segmented palp. Branchial plate ( Fig. 5A ) elongated, with c. 16 respiratory rays, some quite short, others long, proximally with a group of five unequal setae. Palp ( Fig. 4D ) with first segment carrying six long (but unequal) apical setae, and one short subapical and hirsute seta. Terminal palp segment elongated (length c. 1.5 x width) and slightly curved, apically with three claws and three setae. Third endite with two large tooth-bristles, apically serrated, and one long sub-basal seta. First endite with two large sideways-directed bristles and two basal setae. Chaetotaxy of three endites incompletely illustrated ( Fig. 4D ).

T1 ( Fig. 6 A–C) protopodite with an apical group of 14 hirsute setae; two unequal but short a-setae, one long hirsute b-seta and one short hirsute d-seta (the latter c. half the length of the b-seta). Endopodite consisting of asymmetrical prehensile palps: Rpp ( Fig. 6B ) with first segment long, slender and slightly curved, with two sub-apical spines; second segment a subtriangular lobe, bluntly pointed towards the distal side. Lpp ( Fig. 6C ) with first segment broad and straight, with two apical spines; second segment sickle-shaped, with elongated distal expansion.

T2 ( Fig. 5E ) with six segments. First segment with one long and hirsute seta d1. Second segment with one short and hirsute seta d2 (the latter c. half the length of seta d1). Third segment with one apical hirsute seta (e) reaching beyond the tip of the fourth segment. Fourth segment with one long hirsute apical seta (f), reaching the end of the terminal segment. Fifth segment with one short apical hirsute seta (g), half of the length of the seta (f). Terminal segment with one long apical claw (h2), one small subapical seta (h1) and one small apical seta (h3).

T3 ( Fig. 6D, E ) with three segments. First segment with three long and hirsute setae (d1 situated in the middle of the segment, setae d2 and dp situated apically). Second segment longer than wide, with one apical hirsute seta (e), reaching the middle of the third segment. Third segment longer than wide, with one medially hirsute seta (f), half of the length of seta (e). Distal part of the third segment ( Fig. 6E ) with a pincer structure, a long hirsute seta h3, one spine-like seta h1 and one broad seta h2, the latter about 2/3 of the length of seta h3.

CR ( Fig. 7B ) slender, curved, with ventral margin serrated. Apically with two serrated claws (one longer, and one short, the latter about 2/3 of the length of the longest) and two hirsute setae (one longer distal seta, approximately 2/3 of the length of the longest claw, and one short proximal seta, about 1/5 of the length of the longer seta).

CR attachment ( Fig. 7A ) slim, with Triebel’s loop situated in the main branch. vb short; db longer and curved.

Zenker’s organ ( Fig. 7D ) with c. 20 sw, length about 3 times the width, distal end of plate forming a crown of petal-like structures (not illustrated).

Hemipenis ( Fig. 7C ) with ventral lobe of ms rounded, ventral lobe of ls small, with a pointed distal beak. Postlabyrinthal spermiduct with one large and one small loops.

Remarks. We dissected males from Porcos Lake, Ventura Lake, Paraná River and S„o Jo„o Lake (all from the Upper Paraná River Floodplain) and illustrated both the hemipenis and the prehensile palps of the same individual ( Fig. 8 , Table 2 ). Some variability can be noticed, e.g., in the shape of the first segment of Rpp, in the size of spines in the first segment of both palps, and in the shape of the ls and lobe ms of the hemipenis, but again this falls within the range of intra-specific variability and can also be caused by small differences of the position of these structures in the slides.

Description of female (only sexual dimorphic features given here). Valves ( Fig. 9A, B ) elongated, with greatest height situated just behind the anterior margin. Both valves with anterior calcified inner lamellae wider than posterior ones; inner margins not running parallel to valve margins. LVi ( Fig. 9A, C, D ) with an inner groove running parallel to the ventral valve margin ( Fig. 9C ), disappearing in the dorsal side. RVi ( Fig. 9B, E, F ) without an inner groove running parallel to the ventral margins, posterior margin ( Fig. 9F ) carrying a prominent spine. CpRl ( Fig. 9G ) LV overlapping RV along anterior and slightly along ventral margins; surface sparsely set with setae ( Fig. 9J ). CpD ( Fig. 9H ) and CpV ( Fig. 9I ) with greatest width (about half of the length) situated in the middle; in dorsal view, anterior margin of LV with a prominent outer list, RV without such an anterior outer list ( Fig. 9D ).

All characteristics of the limbs largely as in the male, except for the distal chaetotaxy of the A2 and the endopodite of T1.

A2 ( Fig. 10A, B ) with protopodite, exopodite and three-segmented endopodite. Protopodite with three ventral setae (two short and one long and hirsute, reaching beyond the middle of third segment); exopodite reduced to a small plate, with two short and one long setae. First endopodal segment with one ventral aesthetasc Y, one long apical seta (reaching tip of terminal segment) and six hirsute natatory setae: five long, but not reaching tips of apical claws, and one short seta, the latter with length about 1/3 of second endopodal segment. Second endopodal segment undivided, dorsally with one long and one short hirsute seta, ventrally with four t-setae (three long but unequal hirsute setae and one short hirsute seta); apically with three claws (G1, G2, G3), three setae (z1, z2, z3) and one short y 2. Terminal segment ( Fig. 10B ) with two claws (one long GM, one short Gm), aesthetasc y 3 (fused with accompanying seta over short distance only), and with a fine g-seta (shorter than aestethasc y3).

T1 ( Fig. 10C, D ) protopodite apically with a group of 14 hirsute setae; two short a-setae, one long hirsute b-seta and one short hirsute d-seta. Endopodite ( Fig. 10D ) with three plumose apical setae, two long but unequal and one short, about 1/4 of the longer one.

Remarks. We also illustrated valves and carapaces of sexual populations from Ventura Lake ( Fig. 11 ) and from Baía River ( Fig. 12 A–D) of the Upper Paraná River floodplain ( Tables 1, 2 ) and asexual populations from Araguaia, Amazon, Pantanal and Paraná River floodplains ( Figs. 12 E–F, 13–14, Tables 1, 2 ). There are some small differences in length and position of the posterior spine on the RV in the populations of Cypricercus alfredo sp. nov. ( Table 1, Figures 3 , 9 , 11 , 12 , 13 , 14 ). For example, the length of the spine on the RV of this new species ranges between 57 and 110 µm in males, and between 84 and 103 µm in females from the Upper Paraná River floodplain. Only one specimen from Pantanal, Araguaia and Amazon floodplains each was illustrated (SEM pictures) and the length of the spine in these females was 79, 77 and 97 µm, respectively. The position of the spine on the RV also showed some small variability, e.g. straight ( Fig. 3G , in the male and Figs. 9G , 11H , 12D in females), slightly pointing downwards ( Figs. 11C , 12B in males), and slightly pointing upwards ( Fig. 12F in a female) in the populations of C. alfredo sp. nov. of the Upper Paraná River floodplain. The female population from the South Matogrossense Pantanal floodplain also had a straight spine ( Fig. 14C ), while the spines could be either positioned downwards or upwards in the Araguaia River ( Fig. 13C ) and Amazon River floodplains ( Fig. 13H ), respectively. But these differences are minor and fall within the range of intra-specific variability.

Differential diagnosis. We here compare C. alfredo sp. nov. to the other valid Cypricercus species with a posterior spine on the RV (see discussion and Table 3 ). Cypricercus alfredo sp. nov. can at once be distinguished from the South African Cypricercus xhosa Savatenalinton & Martens, 2009b as the latter species has posterior spines on both valves. Cypricercus alfredo sp. nov. is morphologically most closely related to the Brazilian species C. centrurus ( Klie, 1940) and indeed several populations of C. alfredo sp. nov. have over the past years been identified as C. centrurus (see synonymy list above). However, apart from the fact that the latter species is much larger (length c. 1.5 mm in C. centrurus against less than 1.2 mm in C. alfredo sp. nov.), there are also consistent differences in shape and the position of the posterior spine of the RV. The spine in C. alfredo sp. nov. is smaller and has a different shape and position as compared to C. centrurus and this difference (as well as that in the size of the carapace) is consistent over all investigated populations of the new species, distributed over the four major Brazilian floodplains ( Figs. 3 , 8–9 , 11–14 ).

In Cypricercus acanthigera (G. W. M̹ller, 1912) and in Cypricercus unispinifera ( Furtos, 1936) , the Cp is much shorter and higher than in C. alfredo sp. nov. In Cypricercus episphaena (G. W. M̹ller, 1908), the posterior spine is more blunt and broader, while the anterior margins in both valves are more broadly rounded and the anterior LV/RV overlap is much more pronounced. Regarding the three species described from Columbia by Roessler (1986a, b): in Cypricercus variabilis ( Roessler, 1986a) the spine is shorter and more blunt than in C. alfredo sp. nov., while the dorsal margin of the valves is straight and almost parallel to the ventral margin (see discussion); in Cypricercus ariariensis ( Roessler, 1986b) the posterior spines is c. 3 times longer than in the new species, and in Cypricercus elegans ( Roessler, 1986b) this spine is short and blunt, while the posterior margin is more broadly rounded.

Ecology and Distribution. Cypricercus alfredo sp. nov. was recorded from the four largest tropical Brazilian floodplains (Amazon, Araguaia, Pantanal and Paraná), in association with the root systems of the aquatic macrophytes Eichhornia crassipes , E. azurea and Pistia stratiotes . The lowest water temperature recorded was 23.4°C and the highest was 32.2°C. The pH ranged from acid (4) to basic (8). Electrical conductivity ranged between 1.82 µS. cm-1 and 66.2 µS. cm-1 and the dissolved oxygen varied between 1.7 mg. L- 1 and 9.4 mg. L- 1 (see Table 2 ).

Figures

FIGURE 1. Map of Brazil, indicating areas where Cypricercus centrurus, Cypricercus alfredo sp. nov. (asexual and sexual populations) and Cypricercus tiao sp. nov. were found.

FIGURE 3. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–J. Male. A, C, D: arrows pointing to the inner groove. A. LVi (MZUSP 41505). B. RVi (MZUSP 41505). C. LVi, detail of posterior part (MZUSP 41505). D. LVi, detail of anterior part (MZUSP 41505). E. RVi, detail of anterior part (MZUSP 41505). F. RVi detail of posterior part (MZUSP 41505). G. CpRl (MZUSP 41511). H. CpD (MZUSP 41512). I. CpV (MZUSP 41513). J. CpRl, detail of carapace surface (MZUSP 41512). Scale bars: A–B, G–I: 500 µm. C–F: 400 µm. J: 40 µm.

FIGURE 4. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–E. Male. A. A1 (MZUSP 41505). B. A2, without terminal segment (MZUSP 41507). C. A2, terminal segment (MZUSP 41507). D. Mx1, without respiratory plate (MZUSP 41508). E. Rake-like organ (MZUSP 41507). Scale bars: A–E: 50 µm.

FIGURE 5. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–E. Male. A. Mx1, respiratory plate (MZUSP 41510). B. Md-coxa (MZUSP 41505). C. Md-palp (MZUSP 41505). D. Md-palp showing α, β, γ setae (MZUSP 41505). E. T2 (MZUSP 41505). Scale bars: A–E: 50 µm.

FIGURE 6. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–E. Male. A. T1, without prehensile palps (MZUSP 41505). B. T1, Rpp (MZUSP 41508). C. T1, Lpp (MZUSP 41508). D. T3 (MZUSP 41507). E. T3, detail of apical pincer (MZUSP 41507). Scale bars: A–E: 50 µm.

FIGURE 7. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–D. Male. A. CR attachment (MZUSP 41505). B. CR (MZUSP 41505). C. Hemipenis (MZUSP 41505). D. Zenker’s organ (MZUSP 41508). Scale bars: A–D: 50 µm.

FIGURE 8. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–D. Porcos Lake, MZUSP 41527. E–H. Paraná River, MZUSP 41530, I–L. S„o Jo„o Lake, MZUSP 41528. M–P. Ventura Lake, MZUSP 41529. Right (A, E, I, M) and left (B, F, J, N) prehensile palp, and hemipenis (C, D, G, H, K, L, O, P). Scale bars: A–P: 50 µm.

FIGURE 9. Cypricercus alfredo sp. nov. Upper Paraná River floodplain.A–J. Female. A. LVi (MZUSP 41506). B. RVi (MZUSP 41506). C. LVi, detail of posterior part (MZUSP 41506). D. LVi, detail of anterior part (MZUSP 41506). E. RVi, detail of anterior part (MZUSP 41506). F. RVi, detail of posterior part (MZUSP 41506). G. CpRl (MZUSP 41516). H. CpD (MZUSP 41517). I. CpV (MZUSP 41518). J. CpV, detail of spine (MZUSP 41518). Scale bars: A–B, G–I: 500 µm. C–E: 400 µm. F, J: 100 µm.

FIGURE 10. Cypricercus alfredo sp. nov. Upper Paraná River floodplain. A–D. Female. A. A2, without terminal segment (MZUSP 41506). B. A2, terminal segment (MZUSP 41506). C. T1 (MZUSP 41506). D. T1, terminal segment (MZUSP 41506). Scale bars: A–D: 50 µm.

FIGURE 11. Cypricercus alfredo sp. nov. Ventura Lake, Upper Paraná River floodplain. A–E. Male. F–J: Female. A. LVi (MZUSP 41519). B. RVi (MZUSP 41519). C. CpRl (MZUSP 41520). D. CpD (MZUSP 41521). E. CpV (MZUSP 41522). F. LVi (MZUSP 41523). G. RVi (MZUSP 41523). H. CpRl (MZUSP 41524). I. CpD (MZUSP 41525). J. CpV (MZUSP 41526). Scale bars: A–J: 500 µm.

FIGURE 12. Cypricercus alfredo sp. nov. from Baía River (A–D) and Pombas Lake (E–F) of the Upper Paraná River floodplain. A–B. Male. C–F: Female. A. LVi (MZUSP 41531). B. RVi (MZUSP 41531). C. LVi (MZUSP 41532). D. RVi (MZUSP 41532). E. LVi (MZUSP 41533). F. RVi (MZUSP 41533). Scale bars: A–F: 500 µm.

FIGURE 13. Cypricercus alfredo sp. nov. Araguaia (A–E) and Amazon (F–J) River floodplains.A–J. Female. A. LVi (MZUSP 41534). B. RVi (MZUSP 41534). C. CpRl (MZUSP 41535). D. CpD (MZUSP 41536).E. CpV (MZUSP 41537). F. LVi (MZUSP 41538). G. RVi (MZUSP 41538). H. CpRl (MZUSP 41539). I. CpD (MZUSP 41540). J. CpV (MZUSP 41541). Scale bars:A–J: 500 µm.

FIGURE 14. Cypricercus alfredo sp. nov. South Matogrossense Pantanal. A–E. Female. A. LVi (MZUSP 41542). B. RVi (MZUSP 41542). C. CpRl (MZUSP 41543) D. CpD (MZUSP 41544). E. CpV (MZUSP 41545). Scale bars: A–E: 500 µm.