Cyclidium paravorax, Wang & Liu & Wang & Wang & Wang & Wang & Zhao & Pan, 2025

Cyclidium paravorax sp. nov.

urn:lsid:zoobank.org:act:EFC1DA92-72AD-4EA2-936F-12805A06A0EA

Figs 4–5 View Fig View Fig ; Tables 1–2 View Table 1 View Table 2

Diagnosis

The cell about 20–30 × 15–25 µm in vivo; the buccal field occupies about 40–45% of the body length; nine somatic kineties; SKn extends to posterior sub-terminally; one or two macronuclei and one micronucleus; M1 consists of two longitudinal rows and is obviously shorter than M2; M2 has a long-triangle shape; M3 consists of four basal bodies in one row; the scutica is mainly composed of two pairs of kinetosomes; single caudal cilium; freshwater habitat.

Etymology

The species-group name ʻ paravorax ʼ is a composite of the Greek adjective ʻpara-ʼ (beside) and the species-group name ʻ vorax ʼ, indicating its similarity to Cyclidium vorax Pan, 2020 .

Type material

Holotype

CHINA – Heilongjiang Province • Harbin City, Harbin Normal University ; 45°52′3″ N, 126°33′2″ E; 23 Nov. 2022; Xiang Wang leg.; HANU WX-20221123-01 (carbonate-stained slide with 22 specs, the holotype specimen marked with an ink circle). GoogleMaps

Paratypes

CHINA – Heilongjiang Province • 39 specs; same collection data as holotype; HANU WX-20221123-02 GoogleMaps .

Type locality

A freshwater aquarium at Harbin Normal University, Harbin (45°52′3″ N, 126°33′2″ E), Northeast China.

Description

Body about 20–30 × 15–25 µm in vivo, ellipsoidal with flat section in anterior end, posterior end slightly wider ( Fig. 4A, K–N View Fig ). Ratio of length to width about 1.25:1. Buccal field about 40%–45% of body length, with prominent paroral membrane on ventral side ( Fig. 4A, K–P View Fig ; Table 1 View Table 1 ). Cortex smooth. Somatic cilia and cilia of paroral membrane about 6 µm long ( Fig. 4K–N View Fig ), single caudal cilium about 13 µm long ( Fig. 4A, K, N, P View Fig ). Cytoplasm colorless, containing several (approximately 1 µm in diameter) bacteriafilled food vacuoles and variable-sized (0.5–1 µm) granules ( Fig. 4A, K, N View Fig ). Contractile vacuole located near posterior end of cell, approximately 4 µm in diameter ( Fig. 4A, K–L, N View Fig ). Extrusomes not observed; one or two globular macronuclei approximately 7 µm in diameter (eight out of 23 cells examined with two macronuclei); one micronucleus approximately 2 µm across after staining ( Figs 4E View Fig , 5K–L View Fig ). Locomotion by swimming fast, sometimes motionless for long periods.

Altogether 9 or 10 SK extending from near anterior end to near posterior end ( Figs 4B–C View Fig , 5A–B View Fig ), all consisting of dikinetids in its anterior half and widely positioned monokinetids posteriorly ( Fig. 5E, K View Fig ). SKn consisting of 10 to 13 kinetids; SK 1 composed of 14 kinetids. PM generally L-shaped, occupies about 40%–45% of body length, composed of zigzagging structure ( Figs 4D View Fig , 5C View Fig ). M1 consists of two longitudinal rows of monokinetids, shorter than M2 ( Figs 4D View Fig , 5D View Fig ); M2 long-triangle shaped, composed of three longitudinal rows and 8 horizontal rows ( Figs 4D View Fig , 5C View Fig ); M3 obviously smaller and shorter than M1 and M2, bearing one row consisting of four basal bodies ( Figs 4D View Fig , 5C View Fig ). Scutica patterns diversified ( Figs 4F–J View Fig , 5F–J View Fig ), arranged in two groups mainly ( Figs 4D, F View Fig , 5F View Fig ), located near posterior end of PM; each part composed of two and four basal bodies.

Gene sequences

The SSU-rRNA gene sequence of Cyclidium paravorax sp. nov. has been deposited in GenBank database with the accession number OR466404.