Pseudotetrahymena orientalis, Wang & Liu & Wang & Wang & Wang & Wang & Zhao & Pan, 2025

Pseudotetrahymena orientalis gen. et sp. nov.

urn:lsid:zoobank.org:act:AD200533-1E68-4CF5-BE38-1CB4104F26A8

Figs 2–3 View Fig View Fig ; Table 1 View Table 1

Diagnosis

Size in vivo 165–230 × 125–210 μm; anterior end pointed and posterior end broadly rounded; buccal field big and deep, approximately 40% of body length; 19 or 20 somatic kineties; two postoral kineties; M1 and M2 approximately equal length; M2 consists of three parts (M2a, b, c); M3 obviously shorter than M1 and M2; one macronucleus. Micronucleus not observed; freshwater habitat.

Etymology

The species-group name ‘ orientalis ’ (Latin adjective; eastern, occurring in the Orient) refer to the fact that this species was discovered in East Asia.

Type material

Holotype

CHINA – Heilongjiang Province • Harbin City, Dafa international fish market [a freshwater aquarium] ; 45°44′9″ N, 126°35′41″ E; 11 Oct. 2022; Xiang Wang leg.; HANU WX-20221011-01 (carbonate-stained slide with 6 specs, the holotype specimen marked with an ink circle). GoogleMaps

Paratypes

CHINA – Heilongjiang Province • 5 specs; same collection data as holotype; HANU WX-20221011-02 GoogleMaps .

Type locality

A freshwater aquarium at Dafa international fish market in Harbin (45°44′9″ N, 126°35′41″ E), Northeast China.

Description

Size in vivo 165–230 × 125–210 μm; body shape flexible, anterior end narrowed and posterior end broadly rounded usually ( Fig. 2A–B, E, H–I, K View Fig ). When food vacuoles filled by food, 60% of posterior part of cell swells extremely ( Fig. 2A, E View Fig ). Ratio of length to width about 1.5:1. Buccal field usually big, deep, and oval, approximately 40% of body length ( Fig. 2A, E, H–I View Fig ; Table 1 View Table 1 ). Cortical granules spherical, arranged randomly on pellicle ( Fig. 2H, J–K View Fig ). Cytoplasm colorless to deep dark when food vacuoles filled with food ( Fig. 2A, E, H–I, K View Fig ), often containing several big food vacuoles filled with ingested Tetrahymena (food vacuoles about 40 μm in diameter) ( Figs 2K View Fig , 3G View Fig ). Single contractile vacuole (approximately 25 μm in diameter) positioned close to posterior end ( Fig. 2K View Fig ). Extrusomes not observed; single ellipsoid macronucleus, approximately 60 μm across after staining, usually squeezed by food vacuoles, no micronucleus observed ( Fig. 3A–D, H View Fig ). Length of somatic cilia approximately 10 μm, densely arranged. Locomotion mainly by swimming slowly, sometimes rotating forwards. Preying on Tetrahymena .

Altogether 19 or 20 SK arranged latitudinally, extending the entire length of body, consisting of monokinetids ( Figs 2C–D View Fig , 3A–D View Fig ). Two PK; PK1 and PK2 commence anteriorly at level posterior of PM and extend posteriorly nearly to end of cell ( Figs 2F View Fig , 3C View Fig ). Oral structure consisting of one PM and three oral membranelles ( Figs 2C, F–G View Fig , 3E–F View Fig ). PM generally C-shaped, composed of paired basal bodies, organized in zigzagging pattern, extending anteriorly to M2. ( Figs 2F–G View Fig , 3E–F View Fig ). M1 and M2 approximately equal in length, composed of four or three rows of kinetids ( Figs 2F–G View Fig ; 3E–F View Fig ). M2 consisting of three parts, namely M2a, b, c. M2a not obvious anteriorly and conspicuous posteriorly, composed of two rows of kinetids ( Figs 2F–G View Fig , 3E–F View Fig ). M2b obvious, consisting of four rows of kinetids ( Figs 2F–G View Fig , 3E–F View Fig ). M2c divided into two parts, each composed of four rows of kinetids ( Figs 2F–G View Fig , 3E View Fig ). M3 shorter than M1 and M2, containing three rows of kinetids ( Fig. 3E–F View Fig ).

Gene sequences

The SSU-rRNA gene sequence of Pseudotetrahymena orientalis gen. et sp. nov. ahas been deposited in GenBank database with the accession number OR616813.