Strandesia colombiensis 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 : 66-71
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|Strandesia colombiensis Roessler, 1990|
13. Strandesia colombiensis Roessler, 1990 change of rank
Type locality and material
Villavicencio (4°4’N- 73°39’W), Meta department, Colombia. This species was described from temporary pools and lagoons by Roessler (1990b). Type material (holotype and paratypes) is stored in the Natural Sciences Institute of National University of Colombia, no: ICN-MHN-CR-1157 and ICN-MHN-CR 1158,1159, respectively ( Roessler, 1990b).
One female (MZUSP 40455) used for soft part illustrations and five females (MZUSP 40456, MZUSP 40457- MZUSP 40460) used for SEM 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): 1.530 –1.568, H (n=2): 0.916 –0.1016, W (n=3): 0.758 –0.792.
Cp subovate, with greatest height situated in front of the middle. RV with an antero-ventral pointed beak and one posteroventral spine; with calcified inner lamella wide along anterior margin, narrow along ventral and posterior margins; anterior selvage inwardly displaced and not running parallel to valve margin. LV with calcified inner lamella as in RV, and with internal groove along ventral margin. A2 with natatory setae almost reaching the tips of apical claws. CR with ventral margin strongly serrated, its attachment with a Triebel’s loop oval-triangular, situated in the main branch.
Abbreviated redescription of female
LVi ( Fig. 39A View FIGURE 39 ) with greatest height situated in front of the middle; dorsal margin evenly rounded; calcified inner lamella wide long anterior margin, narrow along ventral and posterior margins; internal groove along ventral margin.
RVi ( Fig. 39B, G, H View FIGURE 39 ) greatest height situated in front of the middle; with dorsal margin evenly rounded; calcified inner lamella as in the LVi; with an antero-ventral pointed beak ( Fig. 39G View FIGURE 39 ) and a posteroventral spine ( Fig. 39H View FIGURE 39 ); anterior selvage inwardly displaced, not running parallel to valve margin.
CpLl ( Fig. 39C View FIGURE 39 ) with dorsal margin curved; greatest height situated in front of the middle; external valve surface densely set with setae; with antero-ventral beak and one postero-ventral spine. CpD ( Fig. 39D View FIGURE 39 ) and CpV ( Fig. 39E View FIGURE 39 ) subovate; anteriorly with a skewed rostrum and posteriorly obtusely rounded. CpFr ( Fig. 39F View FIGURE 39 ) subtriangular and 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; 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 longer than the short seta.
A2 ( Fig. 40A, B View FIGURE 40 ) with protopodite, exopodite and three-segmented endopodite. Protopodite with two ventral setae; and one long ventro-distal seta, the latter reaching beyond the tip of the 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 beyond the tip of the last endopodal segment), one group of five long and one short swimming setae (the five long setae almost reaching the tips of apical claws; the short one reaching the middle of second endopodal segment). Second endopodal segment undivided, with two unequal dorsal setae and a group of four unequal, long ventral t setae; apically with three claws (G1 and G3 equally long, G2 slightly shorter than G1), three setae (z1 longest, z2 and z3 slightly shorter than z1) and a short apical aesthetasc y2 ( Fig. 40B View FIGURE 40 ). Terminal segment ( Fig. 40B View FIGURE 40 ) 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. 40 View FIGURE 40 C—chaetotaxy not completely shown) with short (not reaching beyond tip of ss-seta) and smooth α-seta. Second segment ventrally with long (longer than α-seta) stout and hirsute ss-seta, slightly longer than α-seta. Penultimate segment laterally with stout, cone-shaped, hirsute γ-seta. Terminal segment rectan- gular, almost 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. 40 View FIGURE 40 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. 1.5x 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 tip of this endite. First endite with one sideways-directed bristle only, and two long, unequal basal setae.
T1 protopodite ( Fig. 40E View FIGURE 40 ) with two short a-setae, b and d-seta equally long; both hirsute. 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. 40F View FIGURE 40 ) protopodite with seta d1 relatively 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 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 longer than h3).
T3 ( Fig. 41 View FIGURE 41 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 1/5 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 41A View FIGURE 41 ).
CR ( Fig. 41B View FIGURE 41 ) slender and curved, with ventral margin strongly serrated. Proximal claw 2/3 of the length of distal claw. Proximal seta hirsute, ca. 1/4 of distal seta.
CR attachment ( Fig. 41C View FIGURE 41 ) stout, with Triebel’s loop oval-triangular, situated in the main branch; vb long and straight; db short and weakly curved.
This is the first record of Strandesia psittacea colombiensis in Brazil. This subspecies was described by Roessler (1990b) from temporary pools and lakes near the city of Villavicencio in Colombia. The similarity of this species with Strandesia psittacea ( Sars, 1901) was discussed by Roessler (1990b), who then described it as a new subspecies. However, there are significant, and especially consistent, differences in the ratio of L/H of the carapace ( S. psittacea , 1.84–1.84; S. psittacea colombiensis , 1.54 – 1.67); the more curved dorsal region on S. psittacea colombi- ensis; and the differences in frontal view of the carapace, with S. psittacea with a rounded shape, whereas S. psittacea colombiensis has a subtriangular shape.Also, the antero-ventral beak is more rounded in S. psittacea and more pointed in S. colombiensis . These morphological differences support the decision to raise S. psittacea colombiensis to the rank of species, with the name of Strandesia colombiensis .
Roessler (1990a) described Strandesia psittacea colombiensis , while Roessler (1990b) described S. obtusata colombiensis . Following the ICZN, names of species and subspecies have the same nomenclatorial rank. Therefore, S. obtusata colombiensis is a junior homonym of S. psittacea colombiensis . Martens & Behen (1994) therefore renamed the junior name as Strandesia obtusata roessleri . By here raising the rank of S. psittacea colombiensis to species-level, the name S. colombiensis is thus available and can be used.
Strandesia colombiensis is similar to Strandesia psittacea , but it can be distinguished by the higher valves, the more curved dorsal margin, and the more pointed antero-ventral beak. In frontal view, S. colombiensis has a subtriangular shape, whereas S. psittacea is rounded.
Ecology and distribution
Strandesia colombiensis was recorded only from lentic environments, associated with a variety of macrophytes, with different life forms, in the Amazon and Paraná floodplains. This species occurred in acidic to basic environments, with a pH range of 4.2–9.7. Electrical conductivity and dissolved oxygen ranges were 11–63 µS. cm-1 and 0.4–6.1 mg. L-1, respectively (see Table 1). Distribution: Brazil and Colombia.
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