Strandesia nakatanii, Ferreira & Higuti & Martens, 2020

Ferreira, Vitor Góis, Higuti, Janet & Martens, Koen, 2020, Taxonomic revision of Strandesia s. s. (Crustacea, Ostracoda) from four Brazilian floodplains, with the description of three new species, Zootaxa 4760 (1), pp. 1-74 : 48-53

9. Strandesia nakatanii nov. sp.

( Figs. 27–29 )

urn:lsid:zoobank.org:act:01BB076A-979A-4EF2-8FFF-D2AD0D2C8C0E

2017 Strandesia cf. tolimensis sp. 2—Higuti et al.: 7.

Measurements of illustrated specimens (in mm)

L (n=3): 0.784 –0.792, H (n=1): 0.453, W (n=2): 0.446 –0.455.

Diagnosis

Cp elongate with LV slightly overlapping RV anteriorly and posteriorly. RV and LV with greatest height situated well in front of the middle. CpV with LV overlapping RV from posterior to anterior margin, and centrally with a weakly developed flap. RV without anterior inwardly displaced selvage, with a posterior inner list and without postero-dorsal flange. LV with internal groove along margins. A2 with natatory setae reaching the tips of apical claws. T2 with d1 seta twice as long as d2. Caudal ramus slender and its attachment with a semi-oval Triebel’s loop, situated in the main branch.

Type material

Holotype: Female, soft parts dissected in glycerine and stored in a sealed slide. Valves stored in micropaleontological slide ( MZUSP 40432 ).

Paratypes: Three dissected females stored as the holotype ( MZUSP 40433 , MZUSP 40434 , MZUSP 40435 ) . Three females, with carapaces stored in micropaleontological slides ( MZUSP 40436 , MZUSP 40437 , MZUSP 40438 ) .

Type locality

Upper Paraná River floodplain, Xirica Lake in roots of Eichhornia azurea . Coordinates: 22º 46’ 46ʺ S, 53º 22’ 47.3ʺ W, south Brazil.

Etymology

This species is named after the late Dr. Keshiyu Nakatani (State University of Maringá, Nupélia/PEA, Brazil), to acknowledge him as one of the founding fathers of Nupélia (Centre of Research in Limnology, Ichthyology and Aquaculture).

Description of female

LVi ( Fig. 27A ) elongate; anterior margin more broadly rounded than posterior one; greatest height situated well in front of the middle; with calcified inner lamella wide along anterior margin, narrow along ventral and posterior margins; internal groove from anterior to posterior margins.

RVi ( Fig. 27B ) elongate; anterior margin more broadly rounded than posterior one; greatest height situated well in front of the middle; calcified inner lamella as in LVi; with posterior inner list; without anterior selvage and postero-dorsal flange.

CpRl ( Fig. 27C ) with greatest height situated in front of the middle; LV overlapping RV along anterior and posterior margins; external valve surface with many pits and setae. CpD ( Fig. 27D ) subovate; LV overlapping RV anteriorly; greatest width in the middle. CpV ( Fig. 27E ) with LV overlapping RV anteriorly, and centrally with a weakly developed flap. CpFr ( Fig. 27F ), with valves asymmetrical, RV placed higher than LV.

A1 ( Fig. 28A, B ) with seven segments. First segment with one short subapical seta and two long apical setae; WO not seen. Second segment wider than long, with one short dorsal seta and a long ventral RO ( Fig. 28B ). Third segment with two setae. Fourth segment with two short and two long setae. Fifth segment with three long and one short setae. Sixth segment with four long setae. Seventh segment with one short and two long setae, and one aesthetasc Ya slightly longer than the short seta.A2 ( Fig. 28C, D ) with protopodite, exopodite and three-segmented endopodite. Protopodite with two ventral setae (one longer; one shorter) and one long ventro-distal seta reaching the tip of the second endopodal segment. Exopodite reduced to a small plate, with one long and two unequal short setae. First endopodal segment with one ventral aesthetasc Y, one long apical seta (reaching the tip of the last endopodal segment), one group of five long and one short swimming setae (the five long setae reaching to the tips of apical claws, the short one almost reaching the middle of second endopodal segment), and one long apical seta (reaching the tipof the last segment). Second endopodal segment undivided, with two unequal dorsal setae and a group of four long ventral t setae; apically with three claws (G1 slightly longer than G2 and G3; G2 and G3 equally long), three setae (z1 long, almost reaching the tip of G1; z2 and z3 equally long, with 3/4 of the length of z1) and a short y2 ( Fig. 28D ). Terminal segment ( Fig. 28D ) with two claws (one long, GM; one short, Gm), an aesthetasc y3 with an accompanying seta (almost twice as long as the aesthetasc), fused over a short distance only, and a fine g-seta, the latter longer than aesthetasc y3 and shorter than its accompanying seta.

First segment of Md palp ( Fig. 28F , G—respiratory plate not shown) with two long plumose setae, one long smooth seta, and long (reaching beyond tip of ss-seta) and smooth α-seta. Second segment dorsally with three setae (two unequal but long; one short, with the length about 1/3 of the longest), and ventrally with long (but less so than α-seta) and hirsute ss-seta, three long hirsute and one short setae, the latter with length about 2/3 of the longest. Pe- nultimate segment with two groups of setae, dorsally with a group of four unequal but long and smooth setae, laterally with cone-shaped, distally hirsute γ-seta and three smooth subapical setae; ventrally with one long and one short setae. Terminal segment with three claws and three setae. Md coxa ( Fig. 28E ) as typical of the family, elongated with an apical row of strong teeth of variable size, interspaced with some small setae.

Mx1 (fig. 29A chaetotaxy not completely shown) with three masticatory lobes (endites), a two-segmented palp and a large respiratory plate (the later not illustrated). Basal segment of palp with six long apical setae and one short subapical seta. Terminal palp-segment elongated, ca. 1.5x as long as basal width, slightly curved, apically with three claws and three setae. Third endite with two large, serrated bristles. Short subapical seta on third endite, almost reaching the tip of the endite. First endite with two unequal sideways directed bristles, and two long, unequal basal setae.

T1 protopodite ( Fig. 29B, C ) with two short a-setae, one b-seta slightly longer than d-setae. Apically with 10 hirsute setae, subapically with a group of four such setae. Endopodite ( Fig. 29C ) with three unequally long hirsute setae.

T2 ( Fig. 29D ) protopodite with seta d1 long, seta d2 shorter, ca. half of the length of d1. First endopodal segment with one subapical hirsute seta (e). Second endopodal segment medially divided into a- and b-segments; segment “a” with one long apical hirsute seta (f), segment “b” with one seta (g). Third endopodal segment with one apical claw (h2) and two setae (one ventro-apical (h1) with 1/5 the length of h2 and one dorso-apical (h3) with 3/4 the length of h1).

T3 ( Fig. 29E, F ) with three segments. First segment with three long setae (d1, d2, dp). Second segment, longer than wide, with one apical seta (e). Third segment, also longer than wide, with one lateral, hirsute seta (f; distal); distal part of the third segment fused with fourth segment into a modified pincer, with one apical comb-like seta (h2), one small recurved seta, with 1/5 of the length of the comb-like seta, and one longer and distally hirsute seta (h3). Small tooth-like structures present at the base of the comb-like seta (arrowed in Figure 29F ).

CR ( Fig. 29G ) slender, with ventral margin weakly serrated. Proximal claw 2/3 of the length of distal claw. Proximal seta smooth, ca. 1/4 of the length of distal seta.

CR attachment ( Fig. 29H ) stout, with a semi-oval Triebel’s loop, situated in the main branch; vb long and slightly curved; db short and curved

Male unknown.

Differential diagnosis

Strandesia nakatanii nov. sp. resembles Strandesia tolimensis (Roessler, 1990) , but can be distinguished from it by

the more elongated shape, the smaller size and the absence of an anterior selvage and of a postero-dorsal flange on the RV.

Ecology and distribution

Strandesia nakatanii nov.sp. was recorded in lentic and lotic environments, associated with free-floating and rooted floating-stemmed plants, in the Paraná River floodplain. This species occurred in environments with a pH range of 6.4–8.3. Electrical conductivity and dissolved oxygen ranges were 35–68.8 µS. cm-1 and 1.4–12.2 mg. L-1, respectively (see Table 1). Distribution: Brazil.

Figures

FIGURE 27 Carapace and valves of Strandesia nakatanii nov.sp. A, LVi (MZUSP 40435); B, RVi (MZUSP 40435); C, CpRl (MZUSP 40436); D, CpD (MZUSP 40437); E, CpV (MZUSP 40438); F, CpFr (MZUSP 40437). Scale bars: A-E, 500 µm; F, 100 µm.

FIGURE 28 Strandesia nakatanii nov.sp. A, A1 (MZUSP 40434); B, A1 Rome Organ, detail (MZUSP 40434); C, A2 except last segment (MZUSP 40433); D, A2 last segment (MZUSP 40433); E, Md coxal plate (MZUSP 40432); F, Md palp (MZUSP 40432); G, Md palp last segment (MZUSP 40432). Scale bars, 50 μm.

FIGURE 29 Strandesia nakatanii nov.sp. A, Mx1 (MZUSP 40432); B, T1(MZUSP 40432); C, T1 endopodite (MZUSP 40432); D, T2 (MZUSP 40432); E, T3 (MZUSP 40432); F, T3 detail of pincer (MZUSP 40432); G, CR (MZUSP 40433); H, CR attachment (MZUSP 40433). Scale bars, 50 μm.