Strandesia mercatorum ( Vavra, 1895 )

Savatenalinton, Sukonthip & Martens, Koen, 2009, Redescription of the type species of Strandesia Stuhlmann, 1888 and Cypricercus Sars, 1895 (Crustacea, Ostracoda, Cypricercinae), with a description of a new species of Cypricercus from South Africa, Zootaxa 2007, pp. 1-42 : 21-29

Strandesia mercatorum ( Vavra, 1895)

( Figs 13–18 , 20)

Cypris (Strandesia) mercatorum Vavra, 1895: 18

Strandesia mercatorum ( Vavra, 1895) — Müller, 1912: 187.

Material examined. Type material, c. 30 males and females in EtOH, Zanzibar, Africa; collected by F. Stuhlmann, 2 May 1888) (Zoologisches Institut und Zoologisches Museum, Hamburg).

Lectotype (here designated): a male, with soft parts dissected in glycerine in a sealed slide, and valves stored dry in a micropalaeontological slide. (ZIZM-K19115C)

Additional material examined: c. 25 males and females in a sample from C.S.I.R. water research (GEN 568D), collected from Dambo pan, Mozambique, 30 June 1960.

Measurements (in μ m). Female: LV (n=3), L = 1970, H = 1050; RV (n=3), L = 1910, H = 1150; W = 1020. Male: LV (n=1), L = 1810, H = 978; RV (n=1), L = 1720, H = 1040; W = 824.

Diagnosis. Carapace laterally elongated with height c. half the length. RV mid-dorsally with fin-shaped protuberance (anterior end blunt, posterior end pointed), somewhat curved outwardly. Valve surface set with small shallow pits and short setae. LV border slightly swollen and with small hollow channel inside along anterior, ventral and posterior margins; anterior part with broad margin, without inner list. RV with selvage along valve margin. Caudal ramus slender, ventral margin set with 4 groups of finely serrated spines; proximal and distal claws denticulated, set with 2 groups of spines. Hemipenis with medial shield rounded; lateral shield large, wing-like; lateral, finger-like protuberance.

Description of female. Carapace in lateral view ( Fig 13 D–E) elongated, with rounded anterior and posterior margins, length c. twice the height; greatest height situated at one-third of length. Surface set with small shallow pits and short setae ( Fig 14 I–J).

Carapace in dorsal view ( Fig 13 F) egg-shaped, with bluntly pointed anterior and posterior edges, slightly rostrum-like anteriorly; protuberance on RV concave at the middle of inner margin, forming a half circle; greatest width c. half of length; LV overlapping RV anteriorly, posteriorly and ventrally.

Carapace in ventral view ( Fig 13 G) with LV overlapping RV and with slightly protruding valve margin at the middle of carapace. Outer list on RV margin narrow, no outer list on LV.

LV in inner view ( Fig 14 A, E–F) dorsally straight over c. one-third of the length, sloping down to the rounded anterior and posterior margins; ventral margin slightly sinuous in the anterior half; anterior margin broadly rounded. Valve border slightly swollen, with unequal, hollow channel inside (Fig 20), anteriorly larger, ventrally small and narrow and posteriorly medium-size. A continuous groove situated along anterior, ventral and posterior margins. Calcified inner lamella descending into the cavity of the valve, anteriorly wide, without inner list, posteriorly narrower.

RV in inner view ( Fig 14 B, G–H) with both anterior and posterior margins rounded, dorsally with finshape protuberance, anterior end of protuberance sloping, posterior end spine-like; the protuberance somewhat curved outwardly, shape variable, higher or lower, with stronger or weaker posterior spine, in some specimens with rounded edges; selvage set along anterior, ventral and posterior margins; calcified inner lamella narrow, anteriorly wider than posteriorly; anteroventral margin with flange.

Muscle scars as in Fig 14 K.

A1 ( Fig 15 A): first segment with 3 setae (1 short subapical seta, 2 long apical setae) and a small, unsegmented, tube-like proximal Wouters organ ( Fig 15 C–D). Second segment wider than long, with 1 short apical seta and small, short, unsegmented, subapical Rome organ ( Fig 15 B). Third segment bearing 2 short setae (the longer one as long as fourth segment). Fourth segment with 2 short and 2 long setae. Fifth segment with 1 short (reaching beyond the terminal segment) and 3 long setae. Sixth segment with 4 long setae. Terminal segment apically bearing aesthetasc ya and 3 setae, 2 long and 1 short, the latter approximately twothirds of the length of ya.

A2 ( Fig 15 E–F) with penultimate segment undivided. Exopodite with 2 short and 1 long (reaching distal end of first endopodite) setae. First segment of endopodite with 5+1 natatory setae, the shortest one c. half of penultimate segment, the 5 remaining setae long, reaching beyond the end claws of the last two segments; aesthetasc Y short, but with a long terminal part. Penultimate segment undivided, with distally 3 serrated claws and with aesthetasc y2 c. half the length of the terminal segment; z1–z3 setae long; medially with 2 (1 long, 1 shorter (c. two-thirds of the long one)) anterior setae and 4 posterior setae (t1–t4). Terminal segments ( Fig 15 F) with 2 serrated claws, a g-seta and an aesthetasc y3, the latter about as long as the accompanying seta.

Md ( Fig 15 H–I): first segment of palp with a large respiratory plate, 2 subapical setae (s1 and s2), a long seta and relatively long, slender, unsegmented and smooth α-seta. Second segment dorsally with a group of 3 (2 long, 1 short) apical setae, ventrally with a stout, plumose, cone-shape, subapical β-seta, surrounded by 3 hirsute and 1 long bald setae. Penultimate segment with 3 groups of setae; dorsally with a subapical group of 3 long and 1 shorter setae, laterally with 1 stout, long and hirsute, apical γ-seta and 3 smooth subapical setae, ventrally with 1 long and 1 short (c. half of terminal segment) setae. Terminal segment apically with 3 shorter setae and 3 claws, the latter weakly set with setulae.

Rake-like organ ( Fig 15 L) stout, solid and T-shape, with c. 10 blunt teeth.

Mx1 ( Fig 16 A) comprising a large respiratory plate ( Fig 17 A), 3 endites and a 2-segmented palp. Basal segment of palp with an apical group of 5 long setae and 2 (1 long, 1 short) subapical setae. Terminal palpsegment elongated and with 3 claws and 3 setae, the former weakly sclerified. Third endite with 2 large bristles, apically serrated and with c. 8 other setae. Sideways-directed bristles on first endite subequal.

T1 ( Fig 16 B–C) with 2 short a-setae and long b- and d-setae, apically with a group of 14 hirsute, unequal setae. Endopodite a weakly built palp with 3 unequal apical setae. Exopodite a respiratory plate, with 5+1 hirsute setae.

T2 ( Fig 16 D–E) with seta d2 c. half the length of seta d1. Second segment with 1 long apical seta (c. half of penultimate segment). Penultimate segment medially divided into a- and b-segments, the former with 1 long apical seta, the latter with a pair (1 long, 1 spine-like) of apical setae. Terminal segment with an apical, serrated claw and 2 (1 subapical, 1 apical) long setae (length c. one-fourth of claw).

T3 ( Fig 16 F–G) a cleaning limb. First segment with 3 long setae. Second segment with 1 apical seta. Third segment undivided, with medially 1 lateral seta. Terminal segment with an apical pincer and 1 reflexed subapical seta.

Caudal ramus ( Fig 16 I) slender, rather straight and set with 4 groups of fine spines on the ventral margin; claws ( Fig 16 J) straight, set with 2 groups of fine spines (c. two-thirds of their length); distal claw c. one-third of ramus; proximal claw slightly more than half of distal claw; distal end of both claws slightly curved; distal seta hirsute, short (c. half of distal claw). Attachment of the caudal ramus ( Fig 16 H) slim and with Triebel’s loop situated in the main branch; dorsal branch elongated, thin; ventral branch elongated, with distally swollen end.

Description of male. Carapace and valves ( Fig 13 H–J, Fig 14 C–D) as in the female, generally somewhat smaller. All limbs as in the female, except for T1 ( Figs 17 B,C) and the last two segments of A2 ( Fig 15 G) with sexual dimorphism.

Setae z1 and z2 of the penultimate segment of A2 transformed to claws; claws G1 and G3 reduced, the former short, the latter seta-like; Gm on terminal segment of A2 reduced, appearing smaller and shorter (c. 50% of GM); y3 and g-seta different in length between male and female, y 3 in male shorter (c. half the length of GM claw) than that of female (c. two-thirds of the length of GM claw), g-seta in male shorter (less than half the length of GM claw) than that of female (c. slightly more than half the length of GM claw).

T1 with asymmetrical prehensile palps (endopodite forming prehensile palp); right prehensile palp ( Fig 17 C) anteriorly with large triangular lobe and 2 apical spines; left palp ( Fig 17 B) bearing elongated, curved lobe, 1 apical spine and a group of small tubercles.

Zenker’s organ ( Fig 17 F, 18C–I) elongated, length c. 3.2 times the width, set with c. 27 chitinous spiny whorls, distal end set with crowns of petal-like structure encircled by a cone-shaped chitinous sheet, proximal end set with a bunch of hirsute filaments encircled by a cone-shaped chitinous sheet.

Hemipenis ( Fig 16 D–E, 18A–B) relatively large; medial shield rounded; lateral shield large, distal end forming a narrow wing; lateral side with finger-like protuberance. Proximal connected bases of hemipenes with a symmetrical penile attachment. Middle of hemipenis with 1 loop of the postlabyrinthal spermiduct.

Figures

FIGURE 13. Strandesia mercatorum (Vavra, 1895), A – G: Female; H – J: Male. A. LV, external (ZIZM-K 19115 A). B. RV, external (ditto). C. Posterior spine of protuberance (ditto). D. Carapace, right lateral view (ZIZM-K 19115 E). E. Carapace, right lateral view (ZIZM-K 19115 I). F. Carapace, dorsal view (ZIZM-K 19115 E). G. Carapace, ventral view (ZIZM-K 19115 I). H. Carapace, right lateral view (ZIZM-K 19115 F). I. Carapace, ventral view (ZIZM-K 19115 J). J. Carapace, dorsal view (ditto). Scale bars: A – B, D – J: 500 µm; C: 100 µm.

FIGURE 14. Strandesia mercatorum (Vavra, 1895), A – B, E – K: Female; C – D: Male. A. LV, internal (ZIZM-K 19115 A). B. RV, internal (ditto). C. LV, internal (ZIZM-K 19115 C). D. RV, internal (ditto). E. LV, posterior part (ZIZM-K 19115 A). F. LV, anterior part (ditto). G. RV, anterior part (ditto). H. RV, posterior part (ditto). I-J. Valve surface (ditto). K. Muscle scars, LV (ditto). Scale bars: A – D: 500 µm; E – H: 200 µm; K: 100 µm; I – J: 50 µm.

FIGURE 15. Strandesia mercatorum (Vavra, 1895), A – F, H – L: Female, G: Male. A. A 1 (ZIZM-K 19115 A). B. A 1, Rome organ (ditto). C. A 1, Wouters’ organ (ditto). D. A 1, Wouters’ organ (ZIZM-K 19115 B). E. A 2 (ZIZM-K 19115 A). F. A 2, terminal segment (ditto). G. A 2, terminal part (ZIZM-K 19115 C). H. Md-palp (ZIZM-K 19115 A). I. Md-palp, terminal segment (ditto). J. Md-coxa (ZIZM-K 19115 B). K. Md-coxa, apical part (ditto). L. Rake-like organ (ditto). Scale bars: A, H – I: 200 µm; B – G, J – L: 100 µm. points towards the proximal end of limb.

FIGURE 16. Strandesia mercatorum (Vavra, 1895), female. A. Mx 1 (ZIZM-K 19115 B). B. T 1, apical part of protopodite (ZIZM-K 19115 A). C. T 1 (ditto). D. T 2 (ditto). E. T 2, penultimate segment (ditto). F. T 3 (ditto). G. T 3, apical pincer (ditto). H. Attachment of caudal ramus (ditto). I. Caudal ramus (ZIZM-K 19115 B). J. Caudal ramus, claws and setae (ditto). Scale bars: A – C, G, J: 100 µm; D, F, H – I: 200 µm; E: 50 µm.

FIGURE 17. Strandesia mercatorum (Vavra, 1895), A: Female, B – E: Male. A. Mx 1, respiratory plate (ZIZM- K 19115 A). B. Left prehensile palp (ZIZM-K 19115 C). C. Right prehensile palp (ditto). D. Hemipenis (ZIZM-K 19115 D). E. Hemipenis (ZIZM-K 19115 K). F. Zenker’s organ (ZIZM-K 19115 D). Scale bars: A, E – F: 200 µm; B – D: 100 µm.

FIGURE 18. Strandesia mercatorum (Vavra, 1895), male. A. Hemipenis (O. C. 3097). B. Medial and lateral shields of hemipenis (ditto). C. Zenker’s organ (using 7 % KOH, 36 hours) (ditto). D. Detail of distal end plate (O. C. 3098). E. Zenker’s organs (using NaOCl) (ditto). F. Detail of spiny whorls (ditto). G. Detail of proximal end plate (ditto). H. Detail of distal end plate (ditto). I. Zenker’s organ (using NaOCl) (ditto). Scale bars: A, C, E: 100 µm; B, I: 50 µm; D, F – H: 20 µm.