Paranadopsis reducta, Almeida & Higuti & Ferreira & Martens, 2021

Almeida, Nadiny Martins de, Higuti, Janet, Ferreira, Vitor Góis & Martens, Koen, 2021, A new tribe, two new genera and three new species of Cypridopsinae (Crustacea, Ostracoda, Cyprididae) from Brazil, European Journal of Taxonomy 762, pp. 1-48 : 36-40

Paranadopsis reducta gen. et sp. nov.

urn:lsid:zoobank.org:act:8F976A25-DBBF-4F8C-AD42-EA8BCF527C7B

Figs 18–21

‘ Cypridopsis ’ nov. gen. nov. sp. – Higuti et al. 2007: 1935, table 2.

“ Cypridopsis ” n. gen. 2 n. sp. – Matsuda et al. 2015a: 326–327, tables 1–2. — Conceição et al. 2017: 329, table 2; 2018: 184, table 3. — Higuti et al. 2017b: 327, table 2.

Cypridopsis n.gen. 2 n. sp. – Matsuda et al. 2015b: 118, 123, table 1, fig. 5.

“ Cypridopsis ” sp. 2 n. gen. n.sp. – Campos et al. 2018: 6, table 2; 2019: 375, table 1.

Cypridopsis n.gen. 2 n. sp.1 – Higuti et al. 2020: 2, table S1.

Diagnosis

As for the tribe and genus. As the tribe is monogeneric and the genus is monospecific, it is difficult to allocate the different characters and character states to the different taxonomic levels. It is expected that other species in this genus and other genera in this tribe will have basically the same body plan, with slight modifications in shape, size and chaetotaxy of segments in various limbs.

Etymology

The new species is named after the fact that much of the size, shape and chaetotaxy of the segments in the limbs is reduced, especially in the A1.

Type material examined

Holotype BRAZIL • ♀; Upper Paraná River floodplain, Manezinho Backwater ; 22°46′45.3″ S, 53°20′56.4″ W; 2 Mar. 2007; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide; sample EC1; MZUSP 41866 .

Paratypes BRAZIL • 1 ♀; Upper Paraná River floodplain, Manezinho Backwater ; 22°46′47.3″ S, 53°21.1′57″ W; 3 May 2010; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide; valves stored dry in a micropalaeontological slide; sample EC3; MZUSP 41867 • 1 ♀; Upper Paraná River floodplain, Manezinho Backwater ; 22°46′46.5″ S, 53°20′59″ W; 2 Mar. 2007; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide; sample EC2; MZUSP 41868 • 1 ♀; Upper Paraná River floodplain Manezinho Backwater ; 22°46′47.3″ S, 53°21.1′57″ W; 6 Jul. 2011; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide; sample EC3; MZUSP 41869 • 1 ♀; Upper Paraná River floodplain, Manezinho Backwater; 22°46′46.5″ S, 53°20′59″ W; 8 Dec. 2010; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide; sample EC2; MZUSP 41870 • 1 ♀; Upper Paraná River floodplain , Manezinho Backwater; 22°46′47.3″ S, 53°21.1′57″ W; 8 Dec. 2010; J. Higuti leg.; with soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide; sample EC3; MZUSP 41871 • 1 ♀; Upper Paraná River floodplain , Manezinho Backwater ; 22°46′46.5″ S, 53°20′59″ W; 2 Mar. 2007; J. Higuti leg.; with valves stored dry in a micropalaeontological slide after use for SEM; sample EC2; MZUSP 41872 • 2 ♀♀; Upper Paraná River floodplain , Manezinho Backwater ; 22°46′46.5″ S, 53°20′59″ W; 2 Mar. 2007; J. Higuti leg.; carapaces stored dry in micropalaeontological slides after use for SEM; sample EC2; MZUSP 41873 , MZUSP 41874 • 1 ♀; Upper Paraná River floodplain , Manezinho Backwater ; 22°46′46.5″ S, 53°20′59″ W; 3 May 2010; J. Higuti leg.; carapace lost after use for SEM; sample EC2; JH490 .

Measurements of illustrated specimens

See Table 2 .

Description

Female

LVi ( Fig. 18A, C–D ) with broad anterior calcified inner lamella and narrower posterior calcified inner lamella; weak inner list present anteriorly and ventrally, absent posteriorly. RVi ( Fig. 18B, E–F ) with broad anterior calcified inner lamella and narrower posterior calcified inner lamella; inner list fully absent, posteriorly with an inwardly displaced selvage. Both valves elongated and bean-shaped, with curved ventral margin, evenly rounded dorsal margin and with anterior margin more broadly rounded than posterior one. CpRl ( Fig. 18G ) elongated; with the greatest height situated in front of the middle; LV overlapping RV anteriorly (widely so) and posteriorly. External valve surface smooth and set with isolated setae. CpD ( Fig. 18H ) sub-ovate; with greatest width in the middle, and with LV widely overlapping RV anteriorly and less so posteriorly. CpV ( Fig. 18I ) also sub-ovate; with the greatest width in the middle; LV overlapping RV especially anteriorly, but also ventrally and posteriorly and with a gap between the two valves in the anterior third of the length, immediately followed by a central flap of the LV extending beyond the RV.

A1 ( Fig. 19A ) with seven segments. First segment with two long subapical ventral setae; Wouter’s organ not seen. Second segment with one long dorso-lateral seta; Rome organ not seen. Third segment with one ventro-lateral and one dorso-apical setae, the latter slightly shorter than the former one. Fourth to seventh segment greatly reduced in length and chaetotaxy. Fourth segment without setae. Fifth segment with one dorso-apical seta. Sixth segment with three long apical setae. Terminal (seventh) segment with two apical setae, one long and one half that length, and one aesthetasc Ya, about ⅔ of the shorter seta.

A2 ( Fig. 19B, D ) with prodopodite, exopodite and three-segmented endopodite. First segment with one long subapical seta reaching well beyond the tip of the terminal segment. Exopodite reduced to a small plate (not illustrated), with only one long seta reaching the tip of the first endopodal segment; two short accompanying setae missing. First endopodal segment with a ventral aesthetasc Y (approximately half the length of the segment), one subapical long seta, about 2.5 ×the length of aesthetasc Y and hirsute in its distal one fifth, and medially with one short (natatory) seta, almost reaching the tip of the second endopodal segment. Second endopodal segment ventrally with three setae t (one short seta, about twice the length of the terminal segment; one long ca twice the length of the shortest setae, and one of ca ¾ the length of the longest seta); medio-dorsally with two setae, one short and one long (ca twice the length of the short one); apically with three claws (G1, G2, G3) and three setae (z1, z2, z3). Terminal segment ( Fig. 19D ) with two claws, one long (GM), one short (Gm) and one aesthetasc y3 with one accompanying seta, the first one slightly shorter than the latter; seta g missing.

Rake-like organ ( Fig. 19C ) stout, solid, T-shaped, with ca ten apical teeth.

Md-palp ( Fig. 20B ) with four segments. First segment with two long plumose setae (S 1 and S 2), one long smooth seta and one short smooth seta α. Second segment with two unequal, but long dorsal setae; ventrally with one seta β, and one long seta (ca 2 × the length of seta β). Third segment with three groups of setae; dorsally with one group of three long setae and one short (hirsute) seta; apically with a group of three setae, one of which being seta γ; ventro-apically with two unequal setae. Terminal segment with three claws and three setae.

Md-coxa ( Fig. 20A ) elongated, with strong apical teeth, interspaced with some setae.

Mx1 ( Fig. 20C – chaetotaxy not completely illustrated) consisting of three masticatory lobes (endites), a two-segmented palp and a large branchial plate (the latter not illustrated). Branchial plate elongated, with ca 12 respiratory rays, some quite short, others long. First segment of palp subapically with two long setae. Terminal segment of palp with two claw-like setae and two short setae. Third endite apically with several setae, two with a distal tuft of setulae, and one basal, long seta. First endite apically with one basal seta and ca four sideways directed bristles.

T1 ( Fig. 21A ) protopodite with a group of six hirsute setae and two short setae a; setae b and d absent. Endopodite consisting of two apical plumose setae (one long and one short about ½ the length of the long one).

T2 ( Fig. 21B ) with one protopodite segment, one ‘knee’ segment and four endopodite segments. Protopodite and knee-segment with setae d1 and d2 absent. First endopodal segment with one subapical seta e, not reaching the tip of the second endopodal segment. Second endopodal segment with one apical seta f, reaching beyond the tip of the fifth segment. Third endopodal segment with one sub-apical seta g. Terminal endopodal segment with one apically serrated claw h2; setae h1 and h3 absent.

T3 ( Fig. 21C ) with three segments. First segment with three long setae (d1, d2, dp). Second segment with one apical seta e, reaching the middle of the third segment. Third segment medially with one seta f, about ⅓ of the length of the third segment. Distal part of third segment fused with fourth segment into a pincer structure, with a claw h2, one short seta h1 and one long seta h3, about 2× the length of seta h2.

CR absent.

Male

Unknown.

Ecology and distribution

Paranadopsis reducta gen. et sp. nov. was found associated with the root system of E. crassipes , located in some lakes of the Upper Paraná River floodplain. The temperature range of these lakes at the time of sampling was 28.3 to 32.6°C, while the pH range was 5.8 to 7. The electrical conductivity range was 14 to 61 µS. cm-1, and the dissolved oxygen range was 1.5 to 7.6 mg.L- 1 (see Table 4 ).

The species can be considered as rare in the area.

Figures

Fig. 18. Paranadopsis reducta gen. et sp. nov. from the Upper Paraná River floodplain, ♀. A. LVi (MZUSP 41872). B. RVi (MZUSP 41872). C. LVi, detail of posterior part (MZUSP 41872). D. LVi, detail of anterior part (MZUSP 41872). E. RVi, detail of anterior part (MZUSP 41872). F. RVi, detail of posterior part (MZUSP 41872). G. CpRl (MZUSP 41873). H. CpD (MZUSP 41874). I. CpV (JH490). Scale bars: A–B, G–I = 200 µm; C–F = 100 µm.

Fig. 19. Paranadopsis reducta gen. et sp. nov. from the Upper Paraná River floodplain, ♀. A. A1 (MZUSP 41866). B. A2, without the terminal segment (MZUSP 41868). C. Rake-like organ (MZUSP 41869). D. A2, terminal segment (MZUSP 41868). Abbreviations: see text and Material and methods. Scale bars: A–B, D = 50 µm; C = 10 µm.

Fig. 20. Paranadopsis reducta gen. et sp. nov. from the Upper Paraná River floodplain, ♀. A. Md (MZUSP 41869). B. Md-palp (MZUSP 41867). C. Mx1 (MZUSP 41867). Abbreviations: see text and Material and methods. Scale bars: 50 µm.

Fig. 21. Paranadopsis reducta gen. et sp. nov. from the Upper Paraná River floodplain, ♀. A. T1 (MZUSP 41868). B. T2 (MZUSP 41867). C. T3 (MZUSP 41869). Abbreviations: see text and Material and methods. Scale bars: 50 µm.