Strandesia tolimensis 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 : 43-48

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Strandesia tolimensis Roessler, 1990


8. Strandesia tolimensis Roessler, 1990

( Figs. 24–26 View FIGURE 24 View FIGURE 25 View FIGURE 26 )

1990a Strandesia tolimensis n. sp. —Roessler: 802, Figs. 10 View FIGURE 10 , 11 View FIGURE 11 .

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

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

2013 Strandesia tolimensis Roessler, 1990 —Higuti et al.: 196, Figs. 5 View FIGURE 5 , 9C View FIGURE 9 .

Type locality and material

Tolima department, Colombia. This species was described from temporary and semi-permanent pools by Roessler (1990a). Type material (holotype) is stored in the Natural Sciences Institute of National University of Colombia ( ICN-MHN), no ICN-MHN-CR-146-85. The paratypes are stored in the ICN-MHN, no ICN-CR-147-85 to ICN-CR- 160-85, and in the Museum of Natural History of the Andes University no MUA-CR-246-85 to MUA-CR-260-85 ( Roessler, 1990a) .

Material examined

One female (MZUSP 40431)was used for soft part illustrations from Mané Cotia Lake(22°43’18.4”S, 53°17’03.6”W). One female ( MZUSP27442 View Materials ) was used for SEM from Aurélio Lake (22°41’36.5”S, 53°13’52”W) GoogleMaps . One female (OC.3278) was used for SEM from Samambaia Lake 1 (22°36’16”S, 53°22’33”W) GoogleMaps . One female (OC.3279) was used for SEM from Campo Verde Lake 2 (22°39’37.5”S, 53°31’27.7”W) GoogleMaps . All illustrated specimens are from the Paraná River floodplain.

Measurements of illustrated specimens (in mm)

L (n=3): 0.924 –0.959, H (n=1): 0.626, W (n=2): 0.559 –0.613.

Diagnosis (after Higuti et al. 2013)

Cp broadly rounded, with greatest height and width situated in the middle. RV with anterior selvage submarginal, small protruding flange posteriorly; valve surface pitted and set with two types of setae, normal and stiff setae. LV with internal groove along ventral margin. A2 with natatory setae reaching the tips of apical claws; CR and its attachment slender, the last with a Triebel’s loop sub-triangular in the main branch.

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

LVi ( Fig. 24A, G View FIGURE 24 ) with anterior margin more broadly rounded than posterior margin; with calcified inner lamella wide along anterior margin, narrow along ventral margin and wide on posterior margin ( Fig. 24G View FIGURE 24 ); without inner list on anterior calcified inner lamella; internal groove along ventral margin; greatest height situated in the middle.

RVi ( Fig. 24B, H View FIGURE 24 ) with anterior margin more broadly rounded than posterior margin; with submarginal anterior selvage, posteriorly with long and narrow flange ( Fig. 24H View FIGURE 24 ); greatest height situated in the middle; inner lamella as in LVi.

CpLl ( Fig. 24C View FIGURE 24 ) broadly rounded; with greatest height situated in the middle; RV with postero-dorsal flange slightly protruding past LV; Cp surface pitted and set with 2 types of setae, normal and stiff setae. CpD ( Fig. 24D View FIGURE 24 ) with greatest width in the middle; posterior and anterior extremities bluntly rounded; RV overlapping LV with a flap in the anterior region and in the posterior region. CpV ( Fig. 24E View FIGURE 24 ) with posterior flap forming an opening in the carapace, valve margin of LV very weakly sinuous in the middle. CpFr ( Fig. 24F View FIGURE 24 ) slightly 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 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 shorter than the short seta.

A2 ( Fig. 25A, B View FIGURE 25 ) with protopodite, exopodite and three-segmented endopodite. Protopodite with two ventral setae; and one long ventro-distal seta reaching the middle 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 beyond 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 the apical claws; the short one almost reaching the middle of the penultimate segment). Second endopodal segment undivided, with two unequal dorsal setae and a group of four long ventral t setae; apically with three claws (G1 and G3 equally long, G2 slightly shorter than G1), three setae (z1 short with 3/4 of the length of z3, z2 slightly shorter than z3, and z3 longer, reaching the tip of G1) and a short apical aesthetasc y2 ( Fig. 25B View FIGURE 25 ). Terminal segment ( Fig. 25B View FIGURE 25 ) 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 accompanying seta of aesthetasc y3, and similar length to aesthetasc.

First segment of Md palp ( Fig. 25 View FIGURE 25 C—chaetotaxy not completely shown) with long (reaching beyond tip of ssseta) and smooth α-seta. Second segment ventrally with stout and hirsute ss-seta. Penultimate segment laterally with cone-shaped, distally hirsute γ-seta. Terminal segment sub-rectangular, less than 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. 25 View FIGURE 25 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 apical setae, and one short subapical seta. Terminal palp segment elongated, ca. 2x as long as basal width, slightly curved, 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. First endite with one sideways-directed bristle only, and two long, unequal basal setae.

T1 protopodite ( Fig. 25E View FIGURE 25 ) with two short, unequal a-setae; with b and d-seta hirsute and of sub-equal length. 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. 25F View FIGURE 25 ) protopodite with seta d1 long, seta d2 shorter, ca. half 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 beyond the end of the terminal segment. Third endopodal segment with one apical claw (h2) and two setae (one ventro-apical (h1) and one dorso-apical (h3) with the same length, both 1/5 the length of h2).

T3 ( Fig. 26 View FIGURE 26 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, 1/5 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 26A View FIGURE 26 ).

CR ( Fig. 26B View FIGURE 26 ) slender and curved, with ventral margin weakly serrated. Proximal claw 2/3 of the length of distal claw. Proximal seta hirsute, ca. 1/2 of length of distal seta.

CR attachment ( Fig. 26C View FIGURE 26 ) slender, with Triebel’s loop sub-oval, situated in the main branch; vb long and weakly curved; db short and curved.

Male unknown.

Differential diagnosis (after Higuti et al., 2013)

Strandesia tolimensis can be distinguished from the other species in this lineage by the rounded shape of the valves. The species resembles S. obtusata , but differs from it by being less high in lateral view, and wider in dorsal and ventral views, while the posterior protruding flange of the RV in left lateral view is of a different shape: short and rounded in S. obtusata and elongated and narrow in S. tolimensis .

Ecology and distribution

Strandesia tolimensis was recorded in lentic and lotic environments, associated with great variety of macrophytes, with different types of life forms, in the Amazon, Araguaia, Pantanal and Paraná floodplains. This species occurred in acidic to basic environments, with a pH range of 4.7–9.5. Electrical conductivity and dissolved oxygen ranges were 12–162.2 µS. cm-1 and 0.2–8.3 mg. L-1, respectively (see Table 1). Distribution: Brazil and Colombia.