Strandesia lansactohai Higuti & Martens, 2013

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 : 29-34

5. Strandesia lansactohai Higuti & Martens, 2013

( Figs. 15–17 )

2007 Bradleystrandesia gr. elliptica sp. 2—Higuti et al.: 1934, Table 2.

2007 Bradleystrandesia gr. elliptica sp. 3—Higuti et al.: 1934, Table 2.

2009 Bradleystrandesia gr. elliptica sp. 2—Higuti et al.: 664, Table 1.

2009 Bradleystrandesia gr. elliptica sp. 3—Higuti et al.: 664, Table 1.

2009 Bradleystrandesia gr. obtusata sp. 4—Higuti et al.: 664, Table 1.

2010 Bradleystrandesia gr. elliptica sp. 2—Higuti et al.: 267, Table 2.

2010 Bradleystrandesia gr. elliptica sp. 3—Higuti et al.: 267, Table 2.

2010 Bradleystrandesia gr. obtusata sp. 4—Higuti et al.: 267, Table 2.

2010 Bradleystrandesia elliptica species complex—Mormul et al.: 189.

2013 Strandesia lansactohai n. sp. —Higuti et al.: 199, Figs. 6 , 9D .

Type locality and material

Bilé Backwater, in washed roots of Salvinia spec., (PAR179), collected on 08.11.2004 by JH & KM. This is an open lake associated with the Paraná River System. Approximate coordinates: 22°45’15.4”S, 53°17’12”W.

Type material (Holotype) is stored in the Museum of Zoology of the University of São Paulo (MZUSP), no MZUSP 27444. Paratypes are stored in the MZUSP, no MZUSP 27445, MZUSP 27446 and Royal Belgian Institute of Natural Sciences no OC.3280 ( Higuti et al. 2013).

Material examined

One female (MZUSP 40428) was used for soft part illustrations from Leopoldo Lake (22°45’27.6”S, 53°16’15.7”W). Two females ( OC.3280, MZUSP 27445 ) were used for SEM from Bilé Backwater (22°45’15.4”S, 53°17’12”W) . One female ( MZUSP 27447 ) was used for SEM from Aurélio Lake (22°41’36.5”S, 53°13’52”W) . All illustrated specimens are from the Paraná River floodplain.

Measurements of illustrated specimens (in mm)

L (n=3): 0.863 –0.929, H (n=1): 0.452, W (n=2): 0.438 –0.459.

Diagnosis (after Higuti et al. 2013)

Cp laterally elongated, with a small posterodorsal flange on RV; greatest height situated in front of the middle. RV without anterior selvage. LV with internal groove along ventral margin. A2 with natatory setae reaching the tips of apical claws. Md palp with unsegmented long α-seta. CR with ventral margin weakly serrated, its attachment with an oval-triangular Triebel’s loop in the main branch.

Abbreviated redescription of female (after Higuti et al. 2013)

LVi ( Fig. 15A, F ) elongated in lateral view, with anterior margin rounded and posterior margin bluntly and almost symmetrically, pointed; internal groove along ventral margin; greatest height situated in front of the middle; without inner list on anterior calcified inner lamella.

RVi ( Figs. 15B, H ) without anterior selvage; posterior margin somewhat pointed and less broad than LV; with a narrow posterodorsal flange ( Fig. 15H ).

CpLl ( Fig. 15C ) elongated; postero-dorsal flange on RV slightly protruding past LV (indicated by the arrow). CpD ( Fig. 15D ) subovate, with LV overlapping RV anteriorly. CpV ( Fig. 15E ) with valve margin of LV very weakly sinuous in the middle. CpFr ( Fig. 15F ), clearly oblique, with LV being the lower one.

A1 (not illustrated) 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 small ventral RO. Third segment with two setae (the smaller with the length of the fourth segment). 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 shorter than the short seta.

A2 ( Figs. 16A, B ) with protopodite, exopodite and three-segmented endopodite. Protopodite with two ventral setae; and one long ventro-distal seta. Exopodite reduced to a small plate, with one long and two unequal short setae. First endopodal segment with one long 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 just reaching tip of apical claws; the short one almost reaching the middle of third segment). Second endopodal segment undivided, with two unequal dorsal setae and a group of four long ventral t setae; apically with three claws (G1 longest, G2 and G3 slightly shorter than G1); three setae (z1 longest, z2 and z3 shorter than z1) and a short apical aesthetasc y2 ( Fig.16B ). Terminal segment ( Fig.16B ) with two claws (one long GM; one short, Gm), an aesthetasc y3 with an accompanying seta (seta longer than aesthetasc), fused over a short distance only, and a fine g-seta, the latter shorter than aesthetasc y3 and its accompanying seta.

First segment of Md palp ( Fig. 16 C—chaetotaxy not completely shown) with long (reaching beyond tip of ss-seta) and smooth α-seta. Second segment ventrally with long (but less so than α-seta), stout and hirsute ss-seta. Penultimate segment laterally with cone-shaped, hirsute γ-seta. Terminal segment ca. 1.5x as long as basal width. Md coxa (not illustrated) as typical of the family, elongated with an apical row of strong teeth of variable size, interspaced with some small setae.

Mx1 ( Fig. 16 D—chaetotaxy not completely shown) with three masticatory lobes, a two-segmented palp and a large respiratory plate (the latter not illustrated). Basal segment of palp with six long apical setae, and one short subapical seta. Terminal palp segment ca. 2x as long as basal width, slightly curved, apically with three claws (one clearly longer) and three setae. Third endite with two large, distally serrated bristles. Lateral seta on third endite reaching beyond tip of the endite. First endite with only one sideways-directed bristle, and two unequal basal setae.

T1 protopodite ( Fig. 16E ) with two shorta-setae; b-seta twice as long as d-seta. Apically with 10 hirsute setae, subapically with a group of four setae. Endopodite with three unequal long hirsute apical setae (not illustrated).

T2 ( Fig. 16F ) Protopodite with seta d1 long and seta d2 shorter, ca. 3/4 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 shorter seta (g) reaching well beyond tip of terminal segment. Third endopodal segment with one apical claw (h2) and two setae (one ventro-apical seta (h1) with ca. 1/7 the length of h2 and one dorso-apical seta (h3) twice the length of h1).

T3( Fig.17 A—chaetotaxy not completely shown) with three segments. First segment with three long setae (d1, d2 dp).Second segment,longer than wide,with one subapical seta(e).Third segment,also longer than wide,with one lateral, hirsute seta(f);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,with1/5of the length of the comb-like seta,and one longer and distally hirsute seta(h3). CR ( Fig. 17B ) slender and slightly curved, with ventral margin weakly serrated. Proximal claw 2/3 of the length of distal claw. Proximal seta hirsute, c 1/3 of length of distal seta. Distal seta long and hirsute, with the same length of distal claw.

CR attachment ( Fig. 17C ) stout, with oval-triangular Triebel’s loop in the main branch; db long and curved; vb short.

Male unknown.

Differential diagnosis (after Higuti et al. 2013)

This species can be distinguished from the others in this group by the small size and elongated shape of the valves, the complete absence of the anterior selvage of the RV and the morphology of the attachment of the caudal ramus. The species resembles S. elliptica Sars, 1901 , but differs at least in the more elongated shape and the more pointed posterior margin in lateral view.

Ecology and distribution

Strandesia lansactohai was recorded in lentic and lotic environments, associated with variety of macrophytes with different life forms, in the Amazon, Araguaia, Pantanal and Paraná floodplains. This species occurred in acidic to basic environments, with a pH range of 4.4–9.7. Electrical conductivity and dissolved oxygen ranges were 12–222.5 µS. cm-1 and 0.07–11.8 mg. L-1, respectively (see Table 1). Distribution: Brazil.

Figures

FIGURE 6 Strandesia thomazi nov. sp. A, A1 (MZUSP 40403); B, A2 except last segment (MZUSP 40403); C, A2 last segment (MZUSP 40403); D, Md palp showing α, ss, γ setae (MZUSP 40403); E, Mx1 (MZUSP 40403); F, T1 (MZUSP 40405). Scale bars, 50 μm.

FIGURE 9 Strandesia galeati nov. sp. A, A1 (MZUSP 40411); B, A2 except last segment (MZUSP 40412); C, A2 last segment (MZUSP 40412); D, Md palp showing α, ss, γ setae (MZUSP 40411); E, Mx1 (MZUSP 40412); F, T1 (MZUSP 40412). Scale bars, 50 μm.

FIGURE 15 Carapace and valves of Strandesia lansactohai. A, LVi (OC.3280); B, RVi (OC.3280); C, CpLl (MZUSP 27445); D, CpD (MZUSP 27447); E, CpV (MZUSP 27446); F, CpFr (MZUSP 27447); G, LVi detail of posterior margin (OC.3280); H, RVi detail of posterior margin (OC. 3280). Scale bars, A-F, 200 μm; G-H, 100 μm. Reproduced from Higuti et al. (2013) with permission from Brill.

FIGURE 16 Strandesia lansactohai. A, A2 except last segment (MZUSP 40428); B, A2 last segment (MZUSP 40428); C, Md palp showing α, ss, γ setae (MZUSP 40428); D, Mx1 (MZUSP 40428); E, T1 (MZUSP 40428); F, T2 (MZUSP 40428). Scale bars, 50 μm.

FIGURE 17 Strandesia lansactohai. A, T3 pincer (MZUSP 40428); B, CR (MZUSP 40428); C, CR attachment (MZUSP 40428). Scale bars, 50 μm.