Heterocypris exodonta Bonilla-Flores & Karanovic, 2025

Heterocypris exodonta Bonilla-Flores & Karanovic sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Heterocypris aff. salina View in CoL : Vences et al. 2024: 1–9.

Heterocypris cf. salina View in CoL : Echeverría-Galindo et al. 2021: 982–996.

Type locality.

Temporary pond near Nam Co, Southern Tibetan Plateau.

Material examined.

Holotype: China • 1 female, Nam Co , Southern Tibetan Plateau, appendages mounted on a glass slide, and the valves stored in a micropaleontological slide. Size RV: length = 1214 µm, height = 652 µm; LV: length = 1220 µm, height = 690 µm. Echeverría-Galindo et al. (2021) leg. Paratypes: China • 7 females, in addition, eleven RV and nine LV separated; same location as holotype. Size RV: length = 994–1322 µm, height = 544–732 µm; LV: length = 1001–1337 µm, height = 555–734 µm, each specimen’s soft body mounted on a glass slide; valves stored in micropaleontological slides .

Additional material.

China • 1 female collected from Taro Co, STP, site TIP 11-84 (Table 1 View Table 1 ). Size RV: length = 1113 µm, height = 610 µm; LV: length = 1135 µm, height = 624 µm; P. Frenzel leg.

Diagnosis.

(adult females, Figs 2 View Figure 2 , 3 View Figure 3 ) Valves elongated in lateral view. LV overlaps RV on all free margins. It is distinguished by a flattened dorsal margin and a pronounced row of blunt denticles on the anterior and posterior margins of the RV. The inner lamella is broad, and the inner list is well-developed, particularly in the LV. On the internal side, normal pores with a turbine shape but without a bristle in the center. The exopod seta in A 2 is relatively shorter than the length of the second endopodal segment. Upper lip has a broad lip with a patch of pseudochaetae present laterally, immediately above the mouth opening. The second endopodal segment in T 2 is proportionally short and the claw h 2 is long. General shape of lobes is elongated, medium width; curvature of lobes is smooth, continuous; shape of apex is truncate with retrograde beak.

Dimensions.

Female, RV: length = 994–1322 µm, height = 544–732 µm; LV: length = 1001–1337 µm, height = 555–734 µm.

Description of holotype.

Valves: Surface of both valves with numerous normal rimmed (type A 2; Danielopol et al. 2018) pores, each carrying one seta, as well as striations, and foveolae (Fig. 3 A 7 – A 8, B 7 – B 8 View Figure 3 ). In lateral view, lacks a hump on the dorsal side. RV with broad inner lamella and anterior and posterior margins with a well-differentiated row of denticles blunt, with inner list along anterior margin. LV with broad inner lamella in internal view (Fig. 2 A 2, B 2 View Figure 2 ). Normal pores on inner side with turbine-shaped opening and without a bristle in the center (Fig. 2 A 5, A 6, B 5, B 6 View Figure 2 ). Color yellowish (Fig. 3 View Figure 3 ).

Description of soft parts: Antennule (Fig. 4 A View Figure 4 ). Seven-segmented: segment I with three long posterodistal setose setae, and one short, smooth seta anteromedially. Segment II with one smooth distal seta anteriorly, and a Rome organ posteriorly. Segment III with one short, smooth distal seta on each side. Segment IV with four distal setae: two long setae located anteriorly, and two shorter, smooth setae spanning to segment VII. Segments V and VI with same chaetotaxy as segment IV, however, the ventral setae are longer. Additionally, segment VI bears a short alpha seta not present in the preceding segments. Segment VII with three setae distally (two long, one short; long ones setose, short one smooth), plus aesthetasc ya, which is 67 µm long, 2 × longer than the terminal segment with 30 µm.

Antenna (Fig. 4 B View Figure 4 ). Five-segmented: coxa with three short setae; protopod or basis robust, with a smooth ventral distal seta. First endopodal segment with aesthetasc Y with distal dots; with five long swimming setae, and one small additional seta at the anterodistal side. Additionally, this segment includes one long setose seta posterodistally. Second endopodal segment with four t-setae (t 1 – t 4), and aesthetascs y 1, and y 2, all situated posteromedially to posterodistally. Distally, this segment bears three long, thin z-setae and claws G 1, G 2, and G 3. Claws G 1 and G 3 are approximately equal in length, while G 2 is slightly shorter. Terminal segment with an aesthetasc y 3 and claws GM and Gm; the former being more robust and slightly longer than the latter. Exopodal seta measures 205 µm in length, longer than the first (162 µm) and second (98 µm) endopodal segments. The second endopodal segment is 0.48 × the length of the exopodal seta.

Upper lip and rake-like organ (Fig. 5 A, B View Figure 5 ). Measurements on the upper lip were taken as follows: l — length (263 µm), h — height (61 µm), hp — position of the maximum height (186 µm), in accordance with Karan-Žnidaršič and Petrov (2014). A large patch of dense pseudochaetae was present laterally, immediately above the mouth opening. Rake-like organ with nine teeth on the right and ten on the left.

Mandibular coxa (Fig. 4 C View Figure 4 ). With seven teeth, two setose distal setae, and one plumose seta situated subdistally. In addition, three groups of thick, short setae situated between teeth number three and four, and five, and close to inner end. One-seta between first and second, and second and third largest teeth.

Mandibular palp (Fig. 4 D View Figure 4 ). Four-segmented: first segment with respiratory plate (exopod) with six rays similar in length. Ventrally on the same segment, there are four setae: two plumose, one smooth, and one short, thin α-seta. The second segment carries ventrally a group of four long setae and a β-seta that is short, relatively thin, and setose. Dorsally on the same segment there are five long, smooth setae. Penultimate segment with nine smooth setae, and short, thick, setose, γ-seta. Segment IV with six smooth setae distally, two of which are short and thin.

Maxillula (Fig. 4 E View Figure 4 ). Maxillular palp two-segmented: first segment with six long, smooth setae, while second segment cylindrical featuring five smooth setae. The third endite of the maxillula palp features two serrated Zahnborsten. We identified five setae on endite 3, seven on endite 2, and eight on endite 1.

T 1 (Fig. 4 F View Figure 4 ). Endopod with three smooth, unequal setae, situated apically. Exopod (branchial plate) with six hirsute rays; protopod with 13 smooth setae. Two setae a short, setae d and b are present.

T 2 (Fig. 5 C View Figure 5 ). Five-segmented: incompletely divided protopod and five-segmented endopod. Basal segment with seta d 1. First endopodal segment with seta e, overpassing the following segment. Second segment with seta f and third with a small seta near seta g. Terminal segment with short h 1 and h 3 setae, and h 2 transformed into finely serrated, distally curved claw. The length of the second endopodal segment measures 10 µm, representing 51 % the length of the claw, which measures 203 µm.

T 3 (Fig. 5 D View Figure 5 ). Four-segmented: basal segment with d 1, d 2, and dp setae present. Second segment bears a long distal e seta, while the last segment has a slightly shorter f seta. In the distal region of the last segment (fused 4 th segment), with its setae transformed into a pincer-shaped organ (all setae short except h 3).

Uropodal ramus (Fig. 5 E View Figure 5 ). Elongated with two distal claws, Ga (144 µm) exceeding Gp (98 µm) in length, and one shorter setose Sp (61 µm). Additionally, a seta Sa is present and two simple caudal ramus attachments are observed.

Female genital lobe (Fig. 5 F View Figure 5 ). Lobe inverted in Fig. 5 F View Figure 5 to better represent shape. Incomplete crescent shape, with a vaginal opening displaying a tubular intersection. General shape of lobes is elongated, medium width; curvature of lobes is smooth and continuous; shape of apex is truncate with a retrograde beak.

Etymology.

From the Greek exo (outside) and donta (tooth); in relation to the well-defined crenulated teeth (pustules) observed along the anterior and posterior margins of the right valve (Fig. 2 A 1, A 3, A 4, B 1, B 3, B 4 View Figure 2 ).

Reproduction.

Possibly asexual.

Distribution.

Nam Co and Taro Co, STP.

Habitat.

This species was collected from surface sediments in a temporary pond with aquatic vegetation. According to limnological data (Table 1 View Table 1 ), this species inhabits fresh, alkaline, and low oxygenated waters ( 3.5 mg / l).