Trimyema foissneri, Li & Zhuang & Feng & Al-Farraj & Schrecengost & Roưerova & Beinart & Hu, 2023

Li, Ran, Zhuang, Wenbao, Feng, Xiaochen, Al-Farraj, Saleh A., Schrecengost, Anna, Roưerova, Johana, Beinart, Roxanne A. & Hu, Xiaozhong, 2023, Molecular phylogeny and taxonomy of three anaerobic plagiopyleans (Alveolata: Ciliophora), retrieved from two geographically distant localities in Asia and North America, Zoological Journal of the Linnean Society 199 (2), pp. 493-510 : 496-499

Trimyema foissneri sp.nov.

( Figs 2 , 3 ; Table 2)

ZooBank registration: urn:lsid:zoobank.org:act:8AD1A266-44AF-4BD0-A0ED-0E0A6ACFE65E .

Diagnosis: Cell size 20–35 × 10–20 μm in vivo, shape fusiform; 26–32 longitudinal somatic ciliary rows, forming three oblique ciliary girdles, making a turn slightly more than 360°. Region below posterior end of last girdle about 36% of body length, with spare cilia inserted. Caudal cilium about half body length. Epaulet present, including two to four kineties on right dorsal side with four to six kinetosomes, respectively. Ventrolateral fragment comprised of three or four kinetosomes. Oral opening oval, about 30% of cell length. Oral ciliature composed of two semicircular kineties intersecting spatially and one short kinety.

Etymology: We dedicate this new species to Prof. Wilhelm Foissner, University of Salzburg, Austria, in recognition of his significant contribution to the taxonomy of ciliates.

Type locality: Sediments of intertidal zone in Tangdao Bay Park, ºingdao, China (35°55ʹ53.8″N; 120°12ʹ09.1″E) .

Type deposition: The protargol slide (registration number: LR2020062501-01) with the holotype specimen ( Figs 2H, I , 3P ) and several paratype specimens, and another slide (registration number: LR2020062501-02) with paratype specimens were deposited in the Laboratory of Protozoology , Ocean University of China, ºingdao, China. The holotype was marked by a black ink circle on back side of the slide.

Description of Chinese population: Body non-contractile, 20–35 × 10–20 μm in vivo with a ratio of length to width 1.9–2.4:1 and decreased to 1.2–1.7:1 aħer protargol staining. Body fusiform with anterior and posterior end slightly narrowed, dorsal side with slight concavity in posterior-third of body ( Figs 2A–C , 3A–C, J, L ). Macronucleus spherical to broadly ellipsoidal, centrally located or a liưle downward, 5–8 × 4–7 µm in vivo, many nucleoli always aưached to its outer surface in stained cells, but hardly observed in vivo ( Figs 2A, C, G , 3C, D, G, P ). Single globular micronucleus aưached to, or located near, macronucleus, 1–2 μm across in stained cells, usually unrecognizable in vivo ( Figs 2G , 3D ). Endoplasm colourless, containing numerous 1–2 μm across lipid droplets, few acontractile vacuoles and food vacuoles located at posterior part of cell ( Figs 2A , 3A–C, J, M ). Swims slowly by rotating around main body axis, always spiralling to the leħ.

Somatic cilia 5–10 μm long, arranged in 26–32 longitudinal somatic ciliary rows, forming three oblique parallel ciliary girdles, visible in both living and stained individuals ( Figs 2A, D, H, I , 3F–I, L, P , º). Girdles beginning right to several kinetids located at the anterior end of oral kineties, extending downward along the cell surface, slightly more than 360°, with the passing surface a liưle dented ( Figs 2D , 3M ). Region below posterior end of last girdle 5–11 μm long, 36% of body length, with cilia irregularly and loosely arranged, mixing with mucocysts ( Figs 2H, I , 3P , º). One flexible caudal cilium, 11–18 μm long, about half cell length ( Figs 2A–C , 3A, C ). Two to four somatic kineties on right dorsal side of oral area, composed of four to six kinetosomes each, forming a quadrilateral area so-called epaulet ( Figs 2I , 3G–I ). Ventrolateral fragment (VLF) located at right ventral side, about the same level as posterior end of oral kineties, comprised of three or four kinetosomes, arranged obliquely, further from somatic and oral kineties ( Figs 2H , 3P , º). Thin argentophilic lines visible aħer staining, connecting longitudinally somatic ciliary rows ( Figs 2H, I , 3N ).

Oral region oval in shape, 4–8 μm long, about 30% of cell length ( Figs 2A–C , 3J ). Funnel-like buccal cavity, transversely extending from lower half of oral region to dorsal side ( Figs 2C , 3K ). Oral ciliature including three monokinetidal oral kineties on leħ margin of oral region. Two longer oral kineties in a semicircle. Oral kinety 2 (OK2) slightly shorter than oral kinety 1 (OK1). OK1 and OK2 crossed at about midportion or slightly below ( Figs 2E, F, H , 3F, O –º). Oral kinety 3 (OK3) especially short, hard to distinguish on ventral side, but sometimes recognized in leħ lateral view ( Figs 2F , 3F ). Kinetidal composition at the anterior part of OK1 is highly variable, usually formed by three dikinetids but a few individuals appear in other combinations such as two dikinetids or two dikinetids with one trikinetid ( Figs 2E, H , 3O ). Cytopharyngeal fibres thin, S-shaped, only visible in stained cells, 11–17 μm long ( Fig. 3E ).

Figures

Figure 3. Photomicrographs of Trimyema foissneri from life (A–C, J–M) and aħer protargol staining (D–I, N–º). A, B, right lateral views of different individuals, showing different body shape.C, right lateral views of a slightlycompressed individual, arrowhead marks caudal cilia.D, macronucleus and micronucleus (arrowhead).E, cytopharynx fibres (arrowhead).F,lateral view of anterior part of cell, showing two longer oral kineties and a shorter one (arrowhead).G–I, right lateral (G, I) and dorsal (H) view, showing epaulet (arrowheads).J,ventral view,arrowhead indicates oval buccal cavity.K, anterior region, showing buccal cavity (arrowhead).L, lateral view of cell, showing three oblique somatic ciliary girdles.M, anterior part of cell, arrowheads show dents on surface.N, argentophilic lines (arrowhead) connected longitudinal somatic ciliary rows. O, details of oral region, arrowheads indicate kinetids at anterior part of oral kinety 1. P,º, ventral view of the holotype (P) and a paratype (º), showing somatic kineties, oral kineties and different ventro-lateral fragment (redcircle), black arrowhead shows first oral kineties, arrow shows second oral kineties, red arrowheads show mucocysts.Abbreviations:G1, first ciliary girdle; G2, second ciliary girdle;G3, third ciliary girdle; Ma, macronucleus; OK1, first oral kineties; OK2, second oral kineties; VLF, ventrolateral fragment.Scale bars: 15 μm (A–C); 10 μm (G, P, º).

Figure2. Drawings of Trimyema foissneri from life (A–D) and aħer protargol staining (E–I).A, leħ lateral view of a representative individual,arrow shows acontractile vacuole,red arrowhead shows food vacuole, yellow arrowheads showsomatic cilia.B,different body shapein different viewing angles.C, leħ lateral view, showingbuccal cavity (arrow)and position of macronucleus.D, disposition of the ciliary girdles.E, oral ciliature,red dots showingkinetidal composition at the anterior part ofOK1.F,lateral view of oral ciliature,showing theshorter oral kinety 3 (inred).G, macronucleus andmicronucleus (arrowheads),the position of the laưer being variable (1, 2). H, I, ventral(H) anddorsal (I) views of the holotype to show somatic andoral kineties, arrowsshow argentophilic lines connecting longitudinal somaticciliary rows, arrowheads showepaulet.Abbreviations:CC, caudal cilia;Ma, macronucleus;OK, oral kinety; SK, somatickineties; VLF,ventrolateral fragment.Scale bars:15μm (A, C);10 μm (H, I).