Cyclocypris pangi, Yu & Ma & Wang & Zhai, 2022

Yu, Na, Ma, Shunxin, Wang, Qianwei & Zhai, Dayou, 2022, Three new species of non-marine ostracods (Crustacea, Ostracoda) from small water bodies of northern China, ZooKeys 1097, pp. 183-207 : 183

Cyclocypris pangi sp. nov.

Figs 4 , 5 , 6

Cyclocypris sp. - Zhai et al. 2017: 485, fig. 8.

Type locality.

A pond (Y34, Table 1 ) in Beijing, China.

Type material.

Holotype: one male (dyzoc559). Allotype: one female (dyzoc558). Paratypes: two females (dyzoc560, dyzoc561) and two males (dyzoc562, dyzoc563). All from the type locality, dissected, valves preserved on the micropalaeontological slides.

Other material.

One female (dyzoc675), from the site Y30 (Table 1 ), with soft parts dissected and valves preserved on a micropalaeontological slide. Two undissected specimens (dyzoc816, dyzoc817), from the site Y30 (Table 1 ), preserved dry on the micropalaeontological slides.

Etymology.

This species is named in the honour of Prof. Qiqing Pang (Hebei GEO University, China) in recognition of his productive work on Mesozoic and Cenozoic ostracods since the 1960s.

Dimensions.

Male, n = 3, LV, length 520-540 μm, height 355-387 μm. Female, n = 4, LV, length 483-558 μm, height 331-390 μm.

Diagnosis.

Cyclocypris species with intermediate-sized (Fig. 4A ), dark-brown carapace. RV overlapping LV anteriorly and ventrally. A2 natatory setae exceeding terminal claws by 55% of length (Fig. 5B ). Prehensile palps slightly asymmetrical, with sub-rectangular trunks, finger of left prehensile palp wider (Fig. 6A, B ). L6 e -seta exceeding end of terminal segment. L7 fourth segment with length almost twice of width, h1 short and slightly curved, not “S-shaped” (Fig. 6C ). Terminal claws of UR not reaching half-length of UR stem (Fig. 6D ). Hp carrying S-shaped structure to interior side of lobe b, lobes a and b with wide distal end (Fig. 6F ).

Description.

Carapace smooth. RV overlapping LV on all directions, and with one lobe-like expansion ventrally (Fig. 4G, H ). Dorsal margin arched. Ventral margin almost straight in RV (Fig. 4D ) and only slightly concave in LV (Fig. 4A-C, F ). Greatest height near middle length. Posterior end more rounded than anterior. Selvage peripheral along antero-ventral and postero-ventral margins (Fig. 4A ). Two inner lists present on each valve (Fig. 4C-F ): interior one most pronounced on anterior margin of RV (Fig. 4E ), weakly expressed on same position of LV (Fig. 4C, F ); exterior one running close to selvage on both valves (Fig. 4C-F ) except postero-ventral part of LV (Fig. 4C, F ). Antero- and postero-ventral parts of RV each with one blunt peg (arrows in Fig. 4D ), corresponding to antero- and postero-ventral sockets on LV (arrows in Fig. 4C ).

A1 (Fig. 5A ) seven-segmented. First segment with one dorsal and two long ventral setae. Second segment with one dorso-apical seta and tiny Rome organ. Third segment with one medium-long dorso-apical seta and one short ventro-apical seta. Fourth segment with two long dorso-apical setae and two short ventro-apical setae. Fifth segment with two long dorso-apical setae, and one long and one short ventro-apical setae. Sixth segment with four long apical setae. Seventh segment with three long apical setae and aesthetasc ya.

Male A2 (Fig. 5B ) five-segmented. Five long natatory setae extending beyond terminal claws with ~ 55% of their lengths. Sixth seta extending to end of next segment. Seta z3 long, reaching to end of terminal claws. Seta z1 well-developed and claw-like, slightly shorter than claws G2 and GM. Claw G1 short, not reaching mid-way of G2. Claw G3 very small and seta-like. Claw Gm almost reaching mid-length of claw GM.

Female A2 (Fig. 5C ) four-segmented. Seta z1 shorter than setae z2 and z3, exceeding mid-length of claw G3. Claws G1, G3, and G2 progressively shorter. Claw Gm long, almost 80% length of claw GM.

Md (Fig. 5D ) palp four-segmented. Seta α short and slim. Seta β very short and stout. Second segment with three long setae. Fourth segment with three claws and two setae.

Mx (Fig. 5E ) palp two-segmented. First segment with four setae on outer apical edge and one seta in sub-apical position near outer edge. Second segment with three long and three short setae.

Male L5 (Fig. 6A, B ) palps asymmetrical. First segment sub-rectangular. Left palp with bluntly rounded end and one sub-apical seta. Right palp slimmer than left, with one minute sub-apical seta. Distal end of right palp hook-like.

Female L5 (not shown, deformed in all specimens examined.) Exopod bearing five soft, thick rays. Other chaetotaxy structures difficult to discern.

L6 (Fig. 5F ) five-segmented. First segment with d1 -seta. Second segment with long e -seta, exceeding end of terminal segment. Third segment with f -seta slightly exceeding end of fourth segment. Fourth segment with two long g -setae, both exceeding beyond end of terminal segment. Fifth segment with short h1 - and h3 - setae and long claw h2.

L7 (Fig. 6C ) four-segmented. First segment with d1 -, d2 - and dp - setae. Second segment with e -seta, not extending to end of third segment. Third segment with f -seta slightly exceeding end of this segment, and g -seta, slightly exceeding end of fourth segment. Fourth segment long, the length almost two times length of width with short h1 - and h2 - setae and long h3 -seta.

UR (Fig. 6D ) robust. Claw Gp exceeding mid-length of claw Ga. Seta Sa not reaching mid-length of claw Ga. Seta Sp short, not reaching base of claw Gp. UR attachment with two long branches.

Hemipenis (Fig. 6F ) stout. Lobe a with wide, truncated distal end. Lobe b shorter than lobe a with wide distal end. Medial lobe h elongated, distally curved. Thin, slightly S-shaped structure with pointed end present to interior side of lobe b.

Remarks.

Cyclocypris is the third most diverse genus in Cyclocypridinae Kaufmann, 1900 and contains 21 species ( Meisch et al. 2019). Except for C. pusilla Sars, 1895 reported from Afrotropical region ( Sars 1895; Meisch et al. 2019), most Cyclocypris species are known from the Nearctic and Palaearctic regions. In China, three Cyclocypris species, C. serena (Koch, 1838), C. globosa (Sars, 1863), and C. ovum (Jurine, 1820), have been reported so far ( Chen 1982; Huang 1986; Wang et al. 1995; Zhang et al. 2006; Kong et al. 2013). Majority of those species are known as fossils or sub-fossils, with the exception of C. serena ( Kong et al. 2013).

The new species has some typical Cyclocypris characteristics. It is small, has a rounded carapace and long swimming setae on the A2; besides, it lacks male bristles on the A2 and has elongated terminal segment on the L7 and a long g -seta on the same appendage. The new species is somewhat similar to C. serena in terms of its size, the overlap of RV and LV, smooth surface of the valves, long swimming setae on the A2, rectangular basal segment of the L5, and short h1 -seta on the L7. However, it can be distinguished from C. serena based on the following characters: (1) the lobes a and b, and the general shape of Hp, are much wider than in C. serena ( Meisch 2000); (2) the length of the L6 e -seta, the UR Sa - and Sp - setae, the number and length of the apical setae on both prehensile palps of the male L5, all differ from C. serena ; (3) with respect to valve morphology, C. serena [0.58-0.63 mm according to Meisch (2000)] is significantly larger than the new species, the inner list on the RV is less pronounced ( Fuhrmann 2012), and the exterior inner list is absent. These differences in valve morphology would help distinguish the two species when dealing with sub-fossil / fossil material. The new species can be easily recognised, among the other 21 congeners, by the presence of a small, S-shaped process next to the lobe b, as well as a slender, distally curved lobe h (Fig. 6F ).

Figures

Figure 4. Cyclocypris pangi sp. nov. A, B female, dyzoc 558 A outer view of LV B inner view of LV C-E female, dyzoc 675 C inner view of LV, with sockets arrowed D inner view of RV, with pegs arrowed E anterior part of (D) showing details of calcified inner lamella F female, dyzoc 560, inner view of LV G sex unknown, dyzoc 816, ventral view of carapace H sex unknown, dyzoc 817, dorsal view of slightly open carapace. Scale bars: 100 μm.

Figure 5. Cyclocypris pangi sp. nov. A male, dyzoc 559 (holotype), A 1 B male, dyzoc 559, A 2 C female, dyzoc 558 (allotype), A 2 D female, dyzoc 558, Md E female, dyzoc 558, Mx F male, dyzoc 559, L 6. Scale bars: 100 μm.

Figure 6. Cyclocypris pangi sp. nov. A male, dyzoc 559, left L 5 B male, dyzoc 559, right L 5 C female, dyzoc 558, L 7 D female, dyzoc 558, UR E female, dyzoc 558, UR attachment F male, dyzoc 559, Hp. Scale bars: 100 μm.