Notodromas semiovata, Zhai & Fan & Wang, 2023

Zhai, Dayou, Fan, Jiawei & Wang, Min, 2023, Ostracods from the Kunming area of SW China, with description of two new species and male records of Cypridopsis vidua (O. F. Müller, 1776), Zootaxa 5323 (2), pp. 183-215 : 187-195

publication ID	https://doi.org/ 10.11646/zootaxa.5323.2.2
publication LSID	lsid:zoobank.org:pub:998911D1-EF22-4100-8648-EC4B0AEF24C1
DOI	https://doi.org/10.5281/zenodo.8221774
persistent identifier	https://treatment.plazi.org/id/186FFE5E-FFFE-5C55-0D9E-0F76FD0CFF1C
treatment provided by	Plazi
scientific name	Notodromas semiovata
status	sp. nov.

Treatment

Notodromas semiovata n. sp.

( Figs 2‒7 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Type locality. Site Y 167 (25°42’18.0”N, 103°06’31.1”E, 1889 m a.s.l.; Table 1 View TABLE 1 ), a small pond (diameter c. 1 m, depth c. 0.5 m) in a valley a few hundred meters away from Xiaohuangtian Village GoogleMaps .

Type material. Holotype: dissected male ( WOC76 ) . Allotype: dissected female ( WOC78 ) . Paratypes: dissected male ( WOC77 ), dissected female ( WOC101 ), dried undissected whole male ( WOC98 ), and dried undissected whole females ( WOC99 , WOC100). All collected from type locality (site Y167; Table 1 View TABLE 1 ) .

Other material examined. Dissected male ( WOC 131) and dissected females ( WOC 87, WOC132, WOC133) from site Y169 ( Table 1 View TABLE 1 ).

Derivation of name. From Latin semi and ovatus, meaning ‘half’ and ‘egg-shaped’, respectively. The species name refers to the semi-ovate flange lobe on postero-ventral part of female LV.

Dimensions. Male (LV or whole carapace) length 0.86‒0.90 mm (n = 4), female length 0.81‒0.83 mm (n = 6). H/L ratio of LV 0.69‒0.74 (n = 7). Width of carapace: male 0.45 mm (n = 1); female 0.46‒0.47 mm (n = 2).

Diagnosis. Carapaces sexually dimorphic. Female LV postero-ventrally with semi-ovate flange flap overlapping RV. Aesthetasc ya of A1 thin, shorter than terminal segment. Longest exopodal seta of A2 extending to about end of first endopodal segment. Male right L5 palp elongate, tapering distally, with curved long clasper. Male left L5 palp shorter, distinctly arched, with curved shorter clasper. Female L5 palps symmetrical, 2-segmented, with one short apical seta. Hp distally with transverse, curved, blunt projection, and internally characterized by two curved, wellsclerotized structures. ZO elongate, with c. 41‒42 rows of spines and funnel-shaped end plates.

Description. (Features for both sexes unless otherwise noted.) In lateral view, valves of both sexes stoutly built ( Figs 2A‒C View FIGURE 2 , 3A‒C View FIGURE 3 ). Dorsal margin strongly arched with apex behind mid-length. Ventral margin straight. Anterior margin broadly rounded, fringed with distinct compressed zone. Posterior margin sexually dimorphic: strongly curved in male, with postero-ventral part depleted ( Figs 2B View FIGURE 2 & 3B View FIGURE 3 ), broadly rounded in female, and in female LV with flange flap at postero-ventral position ( Fig. 2A, C, E & F View FIGURE 2 ). Shell surface with fine pits and pores of different sizes. Pores with or without lips ( Fig. 2F View FIGURE 2 ). In interior view, selvage displaced inwards along free valve margins in both valves ( Figs 2C‒E View FIGURE 2 , 3B, C, E & G View FIGURE 3 ). Flange along anterior margin much wider than rest parts. In female LV, selvage and inner list at postero-ventral part (adjacent to flange flap) curved inwards. Calcified inner lamella narrow in both sexes. Eye-spot visible at antero-dorsal part. Adductor muscle scars with three small scars arranged in line sub-vertically, and one additional scar offset to posterior side ( Fig. 3F View FIGURE 3 ). Internal side of pores with one central chamber circled by about seven poorly defined ones ( Fig. 3D View FIGURE 3 ). In dorsal and ventral views, carapace sub-ovate, with greatest width slightly behind mid-length ( Fig. 4A, B & D View FIGURE 4 ). Ventral surface flat, with outer lists running either side of venter margins, diverging outwards around mouth area. Three rows of seta-bearing pores accompanying outer list ( Fig. 4E View FIGURE 4 ). In female, semi-ovate flange flap of LV overlapping RV at postero-ventral part ( Fig. 4B & C View FIGURE 4 ). Colour slight blackish, translucent.

A1 ( Fig. 5A View FIGURE 5 ) with eight segments, first two of which fused into large base, supporting one short dorsal seta and two long ventral setae. Proximal sclerotized wall of basal segment with notch structure accompanied by small loop (cf. Smith et al. 2022, fig. 16A). Third segment short, bearing one short dorso-apical seta. Fourth segment elongate, with one dorso-apical seta and one tiny ventro-apical seta. Fifth and sixth segments each with two long dorso-apical setae and two unequal small ventro-apical setae. Seventh segment with four long apical setae on interior side and tiny seta α on exterior side. Eighth segment slender, with three apical setae and short aesthetasc ya.

A2 ( Fig. 5B, E & F View FIGURE 5 ) with two protopodal segments, one exopodal segment, and four endopodal segments. Basal segment (coxa) with one proximo-lateral seta and two ventro-subapical setae. Second segment (basis) robust, carrying one long ventro-apical seta extending to about end of fifth segment. Exopod small, with one long seta extending to about end of third segment (first endopodal segment), one medium-length and one short setae. Third segment elongate. Aesthetasc Y 2-segmented, situated at about mid-length of ventral margin. Ventro-apical seta basally swollen, accompanied by clustered pseudochaetae, extending slightly beyond fifth segment. Swimming setae extending to about tips of terminal claws. Sixth seta short and very thin. Fourth segment with two unequal dorso-apical setae and three unequally long t-setae (with t2 being longest). Aesthetasc y1 tiny. Fifth segment dorsoapically with two sets of setae ( Fig. 5E & F View FIGURE 5 ). Exterior set consisting of two or three fine setae extending to about mid-way of terminal segment, corresponding to z-setae in other Cypridoidea groups. Other set consisting of three setae. Interior seta with fine dotted patterns herein provisionally designated as G3 ( Fig. 5E & F View FIGURE 5 ). Shortest, thickest seta with shaped end provisionally designated as G2. Third seta provisionally designated as G1. In male ( Fig. 5E View FIGURE 5 ), G1 significantly reduced than in female ( Fig. 5F View FIGURE 5 ), with slightly curved end. In female ( Fig. 5F View FIGURE 5 ), G1 and G3 being long setae. Relative positions of G1 and G2 different in two sexes ( Fig. 5E & F View FIGURE 5 ). Terminal segment of A2 slender and elongate, ventrally carrying bifurcated structure with aesthetasc (y3) and setal branches. Seta g not observed in specimens examined in this study. Morphologies of Gm (situated to extero-ventral side of GM) and GM sexually dimorphic. In male, Gm longer and slightly thicker than GM, slightly sinuated ( Fig. 5E View FIGURE 5 ). In female, Gm seta-form, fine, and shorter than GM ( Fig. 5F View FIGURE 5 ).

Md ( Fig. 5C & D View FIGURE 5 ) coxa elongate, gently curved, bearing one short extero-sub-apical seta, six progressively smaller, branched masticatory processes on distal edge, and two short setae beside smallest processes. Palp with four weakly divided segments. First segment (basis) dorsally (exteriorly) bearing vibratory plate (exopod; not shown), ventrally (interiorly) with short, slender unnamed seta (herein provisionally designated as ‘S0’), long S1 and S2 setae, and wide (but laterally compressed, very thin) α seta. Second segment (first endopodal segment) short, ventrally with four long plumose setae (grouped setae), one slender plumose accompanying seta, and short wide (but laterally compressed, very thin) β seta, and dorsally (exteriorly) with two long setae. Accompanying seta usually with proximal part weakly sclerotized, and distal part plumose and extending among setae of preceding segment (could otherwise be confused). (For alternative interpretation of setae on first and second segments of Md palp see Smith et al. 2022.) Third segment with rounded inner edge covered in frill of setules, intero-apically with one long plumose seta, apically with four short setae, and exteriorly with four unequally long sub-apical setae. Fourth segment with one long and four shorter apical setae/claws.

Mx ( Fig. 5G View FIGURE 5 ) palp with two segments. First segment sub-apically with one brush-like seta, and antero-apically with four unequal setae. Second segment short and sub-quadrate, with six unequal setae. Proximal protopodal endite with two long setae on basal part.

Male L5 ( Fig. 6A & B View FIGURE 6 ) with protopod and endopod (palp) well sclerotized. Protopod with two short a-setae; sometimes not observed due to weak sclerotization. Setae b and d long, plumose (setules sometimes difficult to observe). Endite with 14 short setae some of which being plumose. Right palp ( Fig. 6A View FIGURE 6 ) elongate, tapering distally, with one soft ventro-apical seta and long, basally swollen, curved clasper. Left palp ( Fig. 6B View FIGURE 6 ) shorter than right, distinctly curved dorsally, depleted at ventro-proximal part, with two very short sub-apical projections and basally swollen, curved clasper. Female L5 ( Fig. 6C View FIGURE 6 ) palps symmetrical, subapically divided (2-segmented), with one short apical seta. Female L5 palps without pseudochaetae like in Notodromas sinensis Neale & Zhao, 1991 and Notodromas trulla Smith & Kamiya, 2014 . L5 exopod not identified in either sex.

L6 ( Fig. 6D View FIGURE 6 ) with five segments. First segment (protopod) robust, without seta. Second segment (first endopodal segment) with seta e extending slightly beyond next segment. Third segment with seta f extending beyond mid-way of fourth segment. Fourth segment with short seta g, and small spur-like protrusion on posterior apical corner. Final segment with relatively long h1 and h3 setae; claw h2 about twice length of h1.

L7 ( Fig. 6E View FIGURE 6 ) with four segments, terminal segment weakly divided from penultimate one. First segment with setae d1, d2, and dp. Second segment with seta e extending beyond mid-way of third segment. Third segment medially with seta f extending slightly beyond terminal segment, sub-apically with a tiny rounded structure. Fourth segment small, with sub-equally long h1‒h3; h3 reflexed.

Ur and attachment ( Fig. 6F & G View FIGURE 6 ) symmetrically developed. Ur distinctly curved at medial part. Ga and Gp claws slender. Gp slightly shorter than Ga and with bifurcated end (or with one short thick pseudochaeta; observed in both sexes). Seta Sp extending to about mid-length of Ga. Seta Sa absent. Ur attachment branched toward dorsal end ( Fig. 6F View FIGURE 6 ), with a few short secondary branches. Length ratios between distal claws and ramus: Ga/ramus being 0.67 in male (n = 2), 0.93 in female (n = 2), Gp/ramus being 0.53‒0.59 in male (n = 2), 0.82 in female (n = 2), indicating relatively longer terminal claws and shorter ramus in female Ur (not shown).

Rake-shaped organ ( Fig. 6H View FIGURE 6 ) basally wide, distally with approximately 12 teeth. Two to three small lateral nodes present mid-way. Number of nodes can be different between two sides.

Hp ( Fig. 7A‒C View FIGURE 7 ) sub-ovate, pear shaped. Inner margin sinuate. Outer margin unevenly broadly rounded. Proximal end contracted. Distal part broad. Curved, hook-like projection extending from distal‒inner edge towards distal‒ outer edge, protruding from near medio-distal part. Distal half of this projection light-coloured, weakly sclerotized (arrowheads in Fig. 7A & B View FIGURE 7 ). Internally, in central area, with two well sclerotized curved structures (‘1’ and ‘2’ in Fig. 7A‒C View FIGURE 7 ). Structure ‘1’ being distal part of brownish sclorotized area in Hp. Structure ‘2’ smaller, more or less independent, resembling depleted moon.

ZO ( Fig. 7D View FIGURE 7 ) elongate, with c. 41‒42 rosettes on central tube. End plates funnel shaped, supported by radiating chitinous rods.

Remarks. Notodromas semiovata n. sp. comes most close to N. sinensis , resembling the latter in the valve shape, the morphologies of male L5 palps and Hp. Nonetheless, N. sinensis differs from Notodromas semiovata n. sp. in the following aspects. First, the flange flap of the female LV of N. sinensis is more protruding in lateral view, situated at a higher position compared with Notodromas semiovata n. sp., and is sub-triangular shaped and more protruding in ventral view (pls I & II of Neale & Zhao 1991). Second, in limb chaetotaxy, the longest exopodal seta of N. sinensis is short, extending only to the mid-way of first endopodal segment (fig. 1 of Neale & Zhao 1991), and setae d1 and f of L7 (fig. 3 of Neale & Zhao 1991) are significantly longer than those of N. semiovata n. sp. Third, the clasper of male right L5 palp of N. sinensis is longer than that of N. semiovata n. sp. (length ratio between clasper and trunk: 0.67 in N. sinensis vs. 0.49‒0.56 in the present specimens (n = 3)), while the clasper of male left L5 palp of N. sinensis is much shorter (length ratio between clasper and trunk: 0.42 in N. sinensis vs. 0.51‒0.59 in the present specimens (n = 3)). (Note: The designation of right and left male L 5 in Neale & Zhao 1991 was reversed compared to that of Meisch 2000, Smith & Kamiya 2014, and the present study.) Fourth, the female L5 palp of N. sinensis is not subdivided into two segments as in N. semiovata n. sp. Fifth, like Notodromas monacha (O. F. Müller, 1776) , the internal structure of Hp of N. sinensis possesses the c‒d complex in the distal‒central area (fig. 5 of Neale & Zhao 1991; fig. 7 of Smith & Kamiya 2014), which is absent in N. semiovata n. sp. Instead, in this area of N. semiovata n. sp. there are two curved structures (labelled ‘1’ and ‘2’ in Fig. 7A‒C View FIGURE 7 ). Sixth, the ZO of N. sinensis (fig. 5 of Neale & Zhao 1991) has c. 50 rosettes, compared with c. 41‒42 in N. semiovata n. sp. Finally, N. sinensis is significantly longer (1.01‒1.13 mm, Neale & Zhao 1991) than the present species (0.81‒0.90 mm).

The following morphologies of N. sinensis illustrated in Neale & Zhao (1991), which deviate from typical chaetotaxy structure of cypridoids, are not included in our comparison above. These morphologies were possibly resulted from abnormal preservation of the specimens or incorrect observation, and need to be treated with caution:

1) A1 chaetotaxy. In fig. 1 of Neale & Zhao (1991), the A1 of N. sinensis has only one ventral seta on the second segment, lacks the minute ventro-apical seta on the fourth segment, the fifth segment has only one ventro-apical seta, the sixth segment lacks the two ventro-apical setae, and the seta α is missing.

2) A2 chaetotaxy. In the A2 of N. sinensis (fig. 1 of Neal & Zhao 1991), there is only one exopodal seta, and the three z-setae were absent.

Notodromas semiovata n. sp. also resembles N. monacha . But like N. sinensis , the flange flap of N. monacha is situated at a higher position compared to N. semiovata n. sp., and is more protruding in both lateral and ventral views ( Meisch 2000; Smith & Kamiya 2014). In the soft parts, it is most easily distinguished from N. semiovata n. sp. by the position of seta e on mid-length of first endopodal segment of the L6, and presence of three distal seta on the female L5 palp ( Meisch 2000). And the internal anatomy of the Hp of N. monacha differs from that of N. semiovata n. sp., for example, in lacking the structures ‘1’ and ‘2’ ( Fig. 7A‒C View FIGURE 7 ).

Notodromas trulla has widened flange flap on both valves of female, and the flange flap on RV partially overlaps that on the LV (figs 2‒3 of Smith & Kamiya 2014). In the soft parts, the features distinguishing N. trulla from the new species include the undivided female L5 palp, the shapes of male L5 palps and Hp, the internal structures of Hp, as well as the stout ZO with numerous fine spines that are difficult to count (figs 6‒9 of Smith & Kamiya 2014).

For Notodromas oculata Sars, 1903 and Notodromas persica Gurney, 1921 , valve shape alone is adequate to distinguish them from Notodromas semiovata n. sp. It is possible that N. serrata Deb, 1984 does not belong to Notodromas ( George & Martens 2003) . Even if it does, the rudimentary original description of this species denies a detailed comparison with other congeners.