Strandesia bicuspis ( Claus, 1892 ) G.W. Müller 1912
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 : 9-13
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|Strandesia bicuspis ( Claus, 1892 ) G.W. Müller 1912|
1892 Acanthocypris bicuspis— Claus: 53, Plate VII, Figs. 1-12 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 ; Plate VIII, Figs. 1-6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 ; Plate XI.
1892 Strandesia bicuspis var. mucronata (Claus) : 53 (fide G.W. Müller 1912)
1892 Acanthocypris bicuspis var. mucronata Claus : 53 (fide G.W. Müller 1912)
Type locality and material
This species was first described by Claus (1892) from an unknown location. Sars (1901) described Neocypris gladi- ator, a synonym of S. bicuspis , based on specimens hatched from dried mud from Itatiba ( Brazil) and Argentina. No holotype was designated for S. bicuspis (Claus) , the repository of potential type materials is unknown (Karanovic 2012).
Two females (MZUSP 40397, MZUSP 40398) were used for soft part illustrations and four females (MZUSP 40399, MZUSP 40400, MZUSP 40401, MZUSP 40402) were used for SEM, all collected from Pontal Lake (22°45’6.2”S, 53°25’24.6”W) in the Upper Paraná River floodplain.
Measurements of illustrated specimens (in mm)
L (n=2): 2.046 –2.102, H (n=1): 0.971, W (n=2): 0.649 –0.660.
Cp elongated. In dorsal view, Cp with a blunt anterior and posterior beak. LV with straight dorsal margin, and internal groove along ventral margin. RV dorsally with a helmet-like protuberance from the anterior to the middle region (anterior end softly curved, posterior end pointed).A2 with natatory setae reaching to half the length of apical claws. Caudal ramus slender and strongly serrated, its attachment with a sub-triangular Triebel’s loop in the main branch.
Abbreviated redescription of female
LVi ( Fig. 2A View FIGURE 2 ) elongated, with straight dorsal margin; calcified inner lamella wide along anterior and posterior margins and narrow along ventral margin; with a submarginal selvage along anterior, ventral and posterior margins; internal groove along ventral margin; greatest height in LVi well ahead of the middle.
RVi ( Fig. 2B View FIGURE 2 ) with calcified inner lamella as in LVi; anteriorly, ventrally and posteriorly without selvage or inner list; dorsally with a helmet-shaped protuberance from anterior to middle region, anterior end softly curved, posterior end pointed; greatest height in RVi in the middle because of dorsal protuberance.
CpRl ( Fig. 2C View FIGURE 2 ) elongated; with a large dorsal protuberance on RV; greatest height situated in the middle. CpD ( Fig. 2D View FIGURE 2 ), with LV slightly longer than RV, especially at the anterior margins, both anterior and posterior ends pointed, anterior end slightly skewed to the right side; greatest width situated in front of the middle. CpV ( Fig. 2E View FIGURE 2 ), with LV slightly extending beyond RV, especially at the anterior end; both anterior and posterior margins with a blunt beak; RV with an outer list running from anterior to posterior edges.
A1 (not illustrated) with seven segments. First segment with one short subapical seta and two long apical setae; WO small. 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 shorter seta.
A2 ( Figs. 3A, B View FIGURE 3 ) 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 ventral aesthetasc Y, one long apical seta (reaching the tip of the second endopodal segment), one group of five long and one short swimming setae (the five long setae almost reaching tips of apical claws; the short one reaching the middle of third segment). Second endopodal segment undivided, with two unequal but long dorsal setae and a group of four unequal ventral t setae; apically with three claws, G1 longer, G2 short, and G3 slightly shorter than G1, three equally long setae (z1, z2 and z3) and a short apical aesthetasc y2 ( Fig. 3B View FIGURE 3 ). Terminal segment ( Fig. 3B View FIGURE 3 ) 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, but longer than the aesthetasc y3 itself.
First segment of Md palp ( Fig. 3 View FIGURE 3 C—chaetotaxy not completely shown) with long (reaching beyond tip of ssseta) and smooth α-seta. Second segment ventrally with long (but less so than alpha seta), stout and hirsute ss-seta. Penultimate segment laterally with elongated cone-shaped, distally hirsute γ-seta. Terminal segment almost 3x as long as basal width, tapering towards the distal side. 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. 3 View FIGURE 3 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. 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 almost the end of the endite. First endite with one sideways-directed bristle only, and two long, unequal basal setae.
T1 protopodite ( Fig. 3E View FIGURE 3 ) with two short, a-setae; b and d-setae equally long. Apically with 10 hirsute setae, subapically with a group of four setae. Endopodite with three unequal, hirsute apical setae (not illustrated).
T2 ( Fig. 3F View FIGURE 3 ) 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 b-segments; segment “a” with one long apical hirsute seta (f); segment “b” with one shorter seta (g) almost reaching halfway along the long claw (h2). Third endopodal segment with one apical claw (h2) and two setae (one ventro-apical (h1) with 1/3 of h2 and one dorso-apical (h3), slightly shorter than h1).
T3 ( Fig. 4 View FIGURE 4 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 4A View FIGURE 4 ).
CR ( Fig. 4B View FIGURE 4 ) slender and curved, with ventral margin strongly serrated in five distinct groups. Proximal claw half the length of distal claw. Proximal seta smooth, ca. 1/5 of length of distal seta.
CR attachment ( Fig. 4C View FIGURE 4 ) stout, with Triebel’s loop sub-triangular, situated in the main branch; vb long and curved; db short.
Strandesia bicuspis can be distinguished from other Strandesia species by the shape of the dorsal protuberance on the RV (more posteriorly pointed than in other Strandesia species with such a dorsal protuberance), and by the elongated LV.
Ecology and distribution
Strandesia bicuspis was recorded in lentic and lotic environments, associated with free-floating plants and on sediment, in the Paraná River floodplain. This species occurred in acidic to basic values, with a pH range of 5.6–7.8. Electrical conductivity and dissolved oxygen ranges were 41.3–114.9 µS. cm-1 and 1.8–7.9 mg. L-1, respectively (see Table 1). Distribution: Neotropical: Argentina, Brazil, Colombia, Paraguay, Suriname and Venezuela. Palaearctic (as alien invasive species): Germany ( Matzke-Karasz et al. 2012).
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