Strandesia psittacea ( Sars, 1901 ) Roessler 1990

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 : 61-66

12. Strandesia psittacea ( Sars, 1901) Roessler 1990

( Figs. 36–38 )

1901 Cypris psittacea n. sp. —Sars: 24, Plate V, Figs. 13-15 .

1990b Strandesia psittacea ( Sars, 1901) — Roessler: 216, Figs. 1-4 .

1990b Strandesia trichosa n.sp. —Roessler: 221, Fig. 1c, f, k , Fig. 2g, h, i , Figs. 5 , 6 nov. syn. (see below ‘remarks’).

Type locality and material

São Paulo and Ipiranga, Brazil. This species was described based on specimens hatched from dried mud by Sars (1901) from these two locations. Repository of type material unknown (Karanovic 2012) .

Material examined

One female (MZUSP 40449) used for soft part illustrations and five females (MZUSP 40450, MZUSP 40451– MZUSP 40454) used for SEM, all from Gavião Lake (22°40’48.6”S, 53°12’58.6”W). All illustrated specimens are from the Paraná River floodplain.

Measurements of illustrated specimens (in mm)

L (n=3): 1.478 –1.543, H (n=2): 0.803 –0.838, W (n=2): 0.717 –0.785.

Diagnosis

Cp elongated, dorsal region smoothly curved; with greatest height situated in front of the middle. RV with an antero-ventral, bluntly pointed beak-like projection; postero-ventrally with one to two spines; with a widely inwardly displaced anterior selvage, not running parallel to the valve margin. Both valves with calcified inner lamella wide along anterior margin, narrow along ventral and posterior margins. LV with inner groove along ventral margin. A2 with natatory setae reaching 3/4 of the length of of apical claws. CR ventrally weakly serrated; its attachment with a triangular Triebel’s loop, situated in the main branch.

Abbreviated redescription of female

LVi ( Fig. 36A ) elongated, with calcified inner lamella wide along anterior margin, narrow along ventral and posterior margins; internal groove along ventral margin; greatest height situated well in front of the middle.

RVi ( Fig. 36B, 36G ) elongated, with calcified inner lamella as in LVi; antero-ventrally with a bluntly pointed beak ( Fig. 36G ) and posteriorly with one spine ( Fig. 36 H—slightly broken in this view); anteriorly with a widely inwardly displaced selvage, not running parallel to the valve margin; reatest height situated well in front of the middle.

CpLl ( Fig. 36C ) with dorsal region smoothly curved; with greatest height situated in front of the middle; external valve surface densely set with setae; antero-ventrally with a bluntly-pointed beak and postero-ventrally with one spine. CpD ( Fig. 36D ) and CpV (36E) views subovate; greatest width situated in the middle, anteriorly with a pointed rostrum, posterior margin more evenly rounded. CpFr (36F) slightly oblique, with LV being the lower valve.

A1 (not illustrated) with seven segments. First segment with one short subapical seta and two long apical setae. Second segment wider than long, with one short dorsal seta and a small ventral RO. Third segment with two setae (the smaller one 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 longer than the short seta.

A2 ( Fig. 37 A-B) with protopodite, exopodite and three-segmented endopodite. Protopodite with two ventral setae, and one long ventro-distal seta, the latter reaching just beyond tip of first 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 second endopodal segment), and a group of five long and one short swimming setae (the five long setae just reaching 3/4 of the length of the 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 ventral t setae; apically with three claws (G1, G2, and G3 equally long), three setae (z1 and z3 slightly shorter than z2, and z2 almost reaching the tip of G2) and a short apical aesthetasc y2 ( Fig. 37B ). Terminal segment ( Fig. 37B ) 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. 37 C—chaetotaxy not completely shown) with long (reaching beyond tip of ssseta) and smooth α-seta. Second segment ventrally with long (slightly longer than α-seta), stout and hirsute ss-seta. Penultimate segment laterally with cone-shaped, stout and distally hirsute γ-seta. Terminal segment ca. 1.5x as long as basal width, tapering. 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. 37 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. twice as long as basal width, slightly curved and tapering, apically with three claws and three setae. Third endite with two large, distally serrated bristles. Lateral seta on third endite, reaching beyond the end of the endite. Fist endite with one sideways-directed bristle only and two long, unequal basal setae.

T1 protopodite ( Fig. 37E ) with two short a-setae; b-seta and d-seta equally hirsute, with d-seta slightly shorter than b-seta. Apically with 10 hirsute setae, subapically with a group of four such setae. Endopodite with three unequal long hirsute apical setae (not illustrated).

T2 ( Fig. 37F ) protopodite with seta d1 relatively long and seta d2 shorter, ca. 2/3 of the length of d1. First endopodal segment with one subapical hirsute seta (e). Second endopodal segment medially divided into a- and bsegments; segment “a” with one long apical hirsute seta (f); segment “b” with one shorter seta (g) reaching beyond the terminal segment. Third endopodal segment with one apical claw (h2) and two setae (one ventro-apical (h1) with 1/7 the length of h2, and one dorso-apical (h3) slightly shorter than h1).

T3 ( Fig. 38 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, with 1/3 of the length of the comb-like seta, and one longer and distally hirsute seta (h3). Small tooth-like structures present near the base of the comb-like seta (arrowed in Figure 38A ).

CR ( Fig. 38B ) slender and curved, with ventral margin serrated. Proximal claw 3/4 of the length of distal claw. Proximal seta hirsute, ca. 2/5 of length of distal seta.

CR attachment ( Fig. 38C ) stout, with Triebel’s loop triangular, situated in the main branch; vb long and straight; db short and curved.

Male unknown.

Remarks

Strandesia trichosa Roessler, 1990 , a Colombian species, resembles Strandesia psittacea ( Sars, 1901) in the general shape, the presence of a postero-ventral spine and and antero-ventral bluntly rounded beak on the RV. The size is also quite similar, L: 1.540 µm, H: 800 µm, W: 785 µm for S. psittacea , and, L: 1.530 µm, H: 804 µm, W: 840 µm for S. trichosa . Roessler (1990b) considered the difference between these two species was based on the caudal ramus, more specifically in the curves of the claws. Here, comparing the morphology of the Brazilian specimens to the description of Roessler (1990b), we do not agree with this decision and thus consider Strandesia trichosa (Roessler, 1990) a junior synonym of Strandesia psittacea ( Sars, 1901) .

Differential diagnosis

Strandesia psittacea is similar to Strandesia colombiensis (see below), but the valves are less high. Both species are well defined by the hirsute external valve surfaces, the bluntly pointed antero-ventral beak and the postero-ventral spine.

Ecology and distribution

Strandesia psittacea was recorded from lentic and lotic environments, associated with a variety of macrophytes with different life forms, in the Amazon, Araguaia and Paraná floodplains. This species occurred in acidic to basic environments, with a pH range of, 4.7–9.7. Electrical conductivity and dissolved oxygen ranges were 12–80.4 µS. cm-1 and 0.2–8.2 mg. L-1, respectively (see Table 1). Distribution: Brazil and Colombia.

Figures

FIGURE 1 Distribution map of Strandesia species of the Amazon, Araguaia, Pantanal and Paraná floodplains.

FIGURE 2 Carapace and valves of Strandesia bicuspis. A, LVi (MZUSP 40402); B, RVi (MZUSP 40402); C, CpRl (MZUSP 40399); D, CpD (MZUSP 40401); E, CpV (MZUSP 40400). Scale bars, 500 μm.

FIGURE 3 Strandesia bicuspis. A, A2 except last segment (MZUSP 40397); B, A2 last segment (MZUSP 40397); C, Md palp showing α, ss, γ setae (MZUSP 40397); D, Mx1 (MZUSP 40397); E, T1 (MZUSP 40397); F, T2 (MZUSP 40397). Scale bars, 50 μm.

FIGURE 4 Strandesia bicuspis. A, T3 pincer (MZUSP 40398); B, CR (MZUSP 40397); C, CR attachment (MZUSP 40397). Scale bars, 50 μm.

FIGURE 5 Carapace and valves of Strandesia thomazi nov. sp. A, LVi (MZUSP 40406); B, RVi (MZUSP 40406); C, CpLl (MZUSP 40407); D, CpRl (MZUSP 40410); E, CpD (MZUSP 40408); F, CpV (MZUSP 40409); G, CpV detail of anterior part; H, CpFr (MZUSP 40408); I, LVi detail of posterior part (MZUSP 40409). Scale bars, A-F, H, 500 μm; G, 300 μm; I, 400 μm.

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 13 Strandesia obtusata. Male. A, T1 (MZUSP 40414); B, right prehensile palp (MZUSP 40415); C, left prehensile palp (MZUSP 40415); D, T2 (MZUSP 40414); E, T2 detail of short seta on the penultimate segment (MZUSP 40414); F, T3 (MZUSP 40415); G, T3 detail of pincer (MZUSP 40415); H, CR (MZUSP 40414); I, CR attachment (MZUSP 40414); J, Zenker organ (MZUSP 40414); K, hemipenis (MZUSP 40414). Scale bars, 50 μm.

FIGURE 14 Strandesia obtusata. Female.A, A2 except last segment (MZUSP 40422); B, A2 last segment (MZUSP 40422); C, T1 (MZUSP 40423); D, T1 endopodite (MZUSP 40423). 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 36 Carapace and valves of Strandesia psittacea. A, LVi (MZUSP 40450); B, RVi (MZUSP 40450); C, CpLl (MZUSP 40453); D, CpD (MZUSP 40451); E, CpV (MZUSP 40452); F, CpFr (MZUSP 40454); G, RVi detail of anterior margin (MZUSP 40450); H, RVi detail of spine (broken) (MZUSP 40450). Scale bars, A-E, 1.000 μm; F-G, 500 µm; H, 50 µm.

FIGURE 37 Strandesia psittacea. A, A2 except last segment (MZUSP 40450); B, A2 last segment (MZUSP 40450); C, Md palp showing α, ss, γ setae (MZUSP 40449); D, Mx1 (MZUSP 40449); E, T1 (MZUSP 40449); F, T2 (MZUSP 40449). Scale bars, 50 μm.

FIGURE 38 Strandesia psittacea. A, T3 pincer (MZUSP 40450); B, CR (MZUSP 40449); C, CR attachment (MZUSP 40449). Scale bars, 50 μm.