Cypricercus cuneatus Sars, 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 : 4-11

Cypricercus cuneatus Sars, 1895

( Figs 1–5 , 21 )

Material examined. Type material ( SAM A11140, Cape of Good Hope III, specimens raised from dried mud in Oslo by G. O. Sars), c. 50 males and females.

Lectotype (here designated): A male, from SAM A11140, with soft parts dissected in a sealed glycerine slide and valves stored dry in a micropalaeontological slide (no. SS469 — SAM was unable to provide new catalog numbers).

Paralectotypes: all other syntypes from SAM A11140 become paralectotypes. Specimens used for description and illustration: SS469–484.

Measurements (mean, in μ m). Female: LV (n=2), L = 958, H = 466.5; RV (n=2), L = 942, H = 471.5; W = 436. Male: LV (n=2), L = 987.5, H = 474.5; RV (n=2), L = 947, H = 475; W = 438.

Diagnosis. Carapace laterally elongated, cuneiform (height slightly less than half of the length), greatest height slightly in front of the middle. LV overlapping RV, considerably at the anterior, and slightly at the ventral side. Carapace in dorsal view with LV overlapping RV. LV in inner view with wide anterior inner lamella and with 2 inner lists. RV with anterior and posterior submarginal selvage. Rome organ on A1 small and short. A2 with natatory setae long (extending beyond the tips of claws of the last two segments). Caudal ramus slender, ventral margin serrate with fine setulae; proximal and distal claws slim, set with minute setulae. Hemipenis with medial shield round, lateral shield subquadrate.

Description of female. Carapace in lateral view ( Fig 1 A–C) elongated, cuneiform, with a length of c. 2.2 times the height; anterior margin rounded, posterior margin bluntly pointed in the middle; greatest height situated slightly in front of the middle; dorsal margin arched; ventral margin straight medially, anterior half slightly sinuous, posterior half curved upward from the middle to the posterior pointed end. Valve surface ( Fig 1 D–F) finely ornamented with shallow reticulation and with dispersed setae.

Carapace in dorsal view ( Fig 1 G) elongated, elliptical; greatest width slightly more than height and situated near the middle; both ends bluntly pointed, LV overlapping RV, distinctly so anteriorly, slightly posteriorly.

Carapace in ventral view ( Fig 1 H) with LV overlapping RV. Ventral margin of RV with narrow outer list; ventral margin of LV slightly protruding in the middle of the carapace, outer list absent on this valve.

LV in inner view ( Fig 2 A, E–F) dorsally somewhat curved, sloping down to the anterior and posterior margins; long groove situated along anterior, ventral and posterior margins; anterior margin rounded, with wide border; inner lamella calcified, anteriorly wide and set with 2 inner lists, posteriorly narrower. RV in inner view ( Fig 2 B, G–H) with anterior and posterior submarginal selvages; inner lamella without inner list, anteriorly wider than posteriorly. Muscle scars as in Fig 2 I.

A1 ( Fig 3 A) with first segment bearing 1 dorsal, subapical, shorter seta and 2 ventral, apical, long setae, as well as a proximal Wouters organ ( Fig 3 B), the latter small, elongated, unsegmented and tube-like, with slightly tumid distal end. Second segment subquadrate, width slightly less than the length, with 1 apical seta and a small, short Rome organ. Third segment bearing 2 slightly hirsute setae (the shorter one slightly longer than the length of the next segment). Fourth segment carrying 2 pairs of setae, dorsally a pair of long setae, ventrally a pair of shorter setae. Fifth segment with 3 long and 1 short setae, the latter reaching slightly beyond the distal end of the next segment. Sixth segment with 4 long setae. Terminal segment with short aesthetasc ya and 3 setae (2 long, 1 short); short seta slightly longer than ya.

A2 ( Fig3 C–D) with exopodite bearing 2 short and 1 long setae; the long one c. two-thirds of the length of the first endopodite. First endopodite segment bearing a short aesthetasc Y, 1 long apical seta (reaching the end of terminal segment) and 6 natatory setae: 5 long and 1 short, the short one considerably less than half of the penultimate segment, the long ones extending beyond the tips of the claws of the last two segments. Penultimate segment undivided, with 3 serrated claws; aesthetasc y2 reaching beyond the end of the terminal segment; setae z1–z3 long; medially with 2 (1 long, 1 short (c. half the length of the long one)) anterior setae and 4 posterior setae (t1–t4). Terminal segment bearing 2 unequal, serrated claws, a short g-seta, and an aesthetasc y3 (c. half the length of the accompanying seta).

Rake-like organ stout, solid, T-shape, with c. 10 apical blunt teeth.

Md ( Fig 3 F) respiratory plate large. First segment of palp with 3 (2 subapical, large, 1 long) setae and 1 αseta, the latter slender, relatively long, distinctly 2-segmented (segmented point c. one-fourth of its length). Second segment dorsally with 3 apical setae, 2 long, 1 short (considerably shorter than half of the long one); ventrally with a subapical β-seta and 4 (3 hirsute, 1 long) setae; β-seta stout, plumose and cone-shaped. Penultimate segment consisting of 3 groups of setae; dorsally with a group of 4 (3 long, 1 shorter) setae, laterally with an apical γ–seta and 3 subapical smooth setae, ventrally with 1 long and 1 short (c. half of the terminal segment) setae; γ–seta stout, hirsute, very long (c. twice the length of terminal segment). Terminal segment ( Fig 3 G) set with 3 setae and 3 claws.

Mx1 ( Fig 4 A) palp 2-segmented; basal segment with 5 long but unequal, apical setae and 2 (1 long, 1 short) subapical setae, terminal segment elongated, with 3 weakly sclerified claws and 3 setae. Third endite with 2 large bristles, apically serrated, and c. 8 other setae. Sideways-directed bristles on first endite unequal, the long one c. twice the length of the shorter one.

T1 ( Fig 4 B) protopodite with an apical group of 14 hirsute, unequal setae as well as 2 short a-setae, 1 long b-seta and 1 long d-seta. Endopodite a weakly built palp with 3 apical setae, exopodite forming a branchial plate, with 5+1 hirsute setae.

T2 ( Fig 4 C–D) with 2 hirsute d-seta, d2 shorter than d1 seta (d2 c. two-thirds of d1). Second segment with 1 long apical seta (reaching beyond the end of the penultimate segment). Penultimate segment divided into a and b segments; the former with 1 long apical seta, the latter with 2 (1 short, 1 spine-like) apical setae. Terminal segment with a claw as long as the penultimate segment, finely serrated (over c. half of its length), and with 2 (1 subapical, 1 apical) long setae (length c. one third of claw).

T3 ( Fig 4 E–F) with first segment bearing 3 unequal, but long setae. Second segment with 1 apical seta. Third segment undivided, with medially 1 lateral seta. Terminal segment apically with a pincer structure and 1 reflexed subapical seta.

Caudal ramus ( Fig 4 G) apically with 2 long serrated claws and 2 setae. Length of proximal claw c. twothirds of distal claw; distal claw c. one-third of ramus; both claws almost straight, distally slightly curved. Distal seta long (c. two-thirds of distal claw and as long as proximal claw). Ramus slender, with fine setulae along the ventral margin. Attachment of the caudal ramus slender, distally with Triebel’s loop in the middle branch, dorsal branch elongated, slim, ventral branch distally swollen.

Description of male. Carapace and valves ( Fig 1 I–L, Fig 2 C–D) as in the female, no sexual dimorphism in size present. All limbs as in the female, except for A2 ( Fig 3 E) and T1 ( Fig 5 A–B) and reproductive organs. Penultimate segment of A2 with claw-like z1- and z2-setae and with claws G1 and G3 reduced to setae. Terminal segment with reduced Gm claw, being smaller and shorter than that in female. T1-endopodites forming asymmetrical prehensile palps; right palp ( Fig 5 B) anteriorly with triangular lobe and 2 apical spines. Left palp ( Fig 5 A) anteriorly with elongated, curved lobe, 2 apical spines and a few small tubercles.

Zenker’s organ ( Fig 5 D) set with spiny whorls (c. 20), length about 3X width, distal end plate forming a crown of petal-like structures. Hemipenis ( Fig 5 C) relatively small, medial shield rounded, lateral shield subquadrate, distal end of lateral shield somewhat pointed. Penile attachment symmetrical, situated at the proximal connected bases of hemipenes. Postlabyrinth spermiduct curved, with two (1 large, 1 small) loops.

Remarks. The morphology of valves and soft parts of C. cuneatus from our study is largely congruent with the original description by Sars (1895) apart from the following differences:

1. In the type specimens we examined, the distal seta of the caudal ramus is as long as the proximal claw, but it is illustrated as being slightly shorter (c. two-thirds of proximal claw) by Sars (1895). Sars (1924) also reported on C. cuneatus and the distal seta of the caudal ramus is not identical to that of original illustration by the shorter length (c. half of proximal claw).

2. The Zenker’s organ illustrated by Sars (1924) is very long (length c. 6 times the width) and set with approximately 40 spiny whorls. Sars (1895) did not show this organ and it is shorter (length c. 3 times the width) and composed of 20 spiny whorls in our examined specimens. It is possible that the specimen in Sars (1924) is a subadult male, as the appearance of this organ between subadult and adult is different; it is long and narrow in the subadult stage, but shorter and wider in adults ( Martens 1986).

3. The length of C. cuneatus recorded by Sars (1924) and in the present study is different. The former record is 1.60 mm. and the latter is 1.00 mm. This difference in length was also indicated by Martens (2001).

4. The size of the male is not distinctly different from female size in our observation, but Sars (1895, 1924) cited that male is somewhat smaller than female.

It is possible that these differences result from an error of the drawing without camera lucida by Sars (1895, 1924) or from variability in different generations in his aquaria, where environmental conditions such as temperature and salinity were not controlled. It is known that such factors can have strong effects on ostracod growth ( Martens 1985) and on valve shape ( Yin et al. 1999). However, since we also have measured the type specimens, we consider the measurement of Sars (1924) to be erroneous.

Figures

FIGURE 1. Cypricercus cuneatus Sars, 1895, A – H: Female; I – L: Male. A. Carapace, right lateral view (SS 474). B. Carapace, left lateral view (ditto). C. Posterior end of carapace in left lateral view (ditto). D – F. Valve surface (ditto). G. Carapace, dorsal view (ditto). H. Carapace, ventral view (ditto). I. Carapace, right lateral view (SS 473). J. Carapace, left lateral view (ditto). K. Carapace, dorsal view (ditto). L. Carapace, ventral view (ditto). Scale bars: A – B, G – L: 200 µm; C: 100 µm; D – F: 50 µm.

FIGURE 2. Cypricercus cuneatus Sars, 1895, A – B, E – I: Female; C – D: Male. A. LV, internal view (SS 470). B. RV, internal view (ditto). C. LV, internal view (SS 469). D. RV, internal view (ditto). E. LV, posterior part (SS 470). F. LV, anterior part (ditto). G. RV, anterior part (ditto). H. RV, posterior part (ditto). I. Muscle scars (ditto). Scale bars: A – H: 200 µm; I: 100 µm.

FIGURE 3. Cypricercus cuneatus Sars, 1895, A – D, F – H: Female (SS 470); E: Male (SS 469). A. A 1 (SS 470). B. A 1, Wouters’ organ (ditto). C. A 2 (ditto). D. A 2, terminal segment (ditto). E. A 2, terminal part (SS 469). F. Md-palp (SS 470). G. Md-palp, terminal segment (ditto). H. Md-coxa (ditto). Scale bars: A, C – D, H: 100 µm; B, E – G: 50 µm.

FIGURE 4. Cypricercus cuneatus Sars, 1895, female. A. Mx 1 (SS 470). B. T 1 (ditto). C. T 2 (ditto). D. T 2, penultimate and terminal segments (ditto). E. T 3 (ditto). F. T 3, apical pincer (ditto). G. Caudal ramus and attachment of caudal ramus (ditto). Scale bars: A – B, D, F: 50 µm; C, E, G: 100 µm.

FIGURE 5. Cypricercus cuneatus Sars, 1895, male (A – D) and Cypricercus inermis (Brady, 1904), male (E – H). A. Left prehensile palp (SS 469). B. Right prehensile palp (ditto). C. Hemipenis (ditto). D. Zenker’s organ (ditto). E. Left prehensile palp (O. C. 3081). F. Right prehensile palp (ditto). G. Hemipenis (ditto). H. Zenker’s organ (O. C. 3082). Scale bars: A – B, E – F: 50 µm; C – D, G – H: 100 µm.

FIGURE 21. Cypricercus cuneatus Sars, 1895, structure of LV. A – E, G – J: O. C. 3096; F: O. C. 3095. Scale bars: A, C: 100 µm; B, F – I: 50 µm; D – E, J: 20 µm.