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GENUS PARALITONOTUS GEN. NOV. Zoobank registration: urn: lsid: zoobank. org:act: CB662085-9DE5-469F-9BC5-ADBE6496AAF1 Diagnosis: Paralitonotidae with right somatic kineties progressively shortened from middle towards dorsal full kinety and perioral kinety; leftmost kinety extending to anterior end of cell. Type species: Paralitonotus foissneri sp. nov. Etymology: Composite of the Greek prefix Παρά- (derive from) and the generic name Litonotus Wresniowski, 1870, referring to the Litonotus -like general ciliary pattern. Masculine gender.

PARALITONOTUS FOISSNERI SP. NOV. (FIGS 2, 3; TABLE 1) Zoobank registration: urn: lsid: zoobank. org:act: 39F1669A-2ED6-41BF-A718-CF3584918B9C Diagnosis: Cell elongate and extremely contractile, with long neck ~40–50% of body length, posterior portion of body conspicuously tail-like; size in extended individuals about 150–300 µm × 30–50 µm; six or seven left and 13–15 right somatic kineties; single subterminal contractile vacuole; two macronuclear nodules and single micronucleus; marine habitat. Type material: A silver proteinate slide with the holotype specimen circled by ink and a second silver proteinate slide with paratype specimens were deposited in Laboratory of Protozoology, Ocean University of China, with registration numbers CY2018101603-1 and CY2018101603-2, respectively. Type locality and ecological features: Intertidal zone of a sandy beach in Qingdao, China (36°16′35.817″N, 120°40′32.0124″E). Water temperature 21 °C and salinity 30 ‰. Etymology: We dedicate this species to Professor Dr Wilhelm Foissner, University of Salzburg, Austria, in recognition of his significant contributions to ciliatology. SSU rDNA sequence: The partial SSU rDNA gene sequence of Pa. foissneri sp. nov. is deposited in GenBank with length 1593 bp, G+C content 42.81% and accession number MW414674. The SSU rDNA gene sequence similarity between Pa. foissneri sp. nov. and its similar species ranges from 0.901 to 0.973 (Fig. 8). Description: Body size highly variable, cell length mostly ~150–300 µm, contracts ≤ 50%, occasionally> 350 µm when fully extended. Main body spindle shaped, ~70–170 µm long, with neck ~40–50% and tail ~15% of cell length (Figs 2A, B, F, 3A–E, I). Cilia in right kineties are ~6 µm long in vivo and densely arranged, whereas those in left kineties are undetectable in live cells. Nuclear apparatus centrally located, comprising two ovoidal macronuclear nodules, each about 10–30 µm × 5–10 µm after silver proteinate staining, and a single micronucleus (Figs 2A, B, D, G, 3K, M). Micronucleus located between two macronuclear nodules (Fig. 3M, arrowhead). Single contractile vacuole subterminally located (Figs 2A, B, 3C), pulsates about every 2 min. Extrusomes scattered in main body (Figs 2F, H, 3H), straight or slightly curved, ~4 µm long in vivo (Fig. 2C). Extrusomes in oral bulge undetected. Cortical granules not observed. Cytoplasm colourless or greyish, with numerous endoplasmic granules (~1–3 µm in diameter) in main body, rendering this region opaque. Locomotion typically by swimming, with anterior portion repeatedly contracting and swinging from side to side, sometimes by gliding on substrate. Ciliary pattern as shown in Figures 2E, G–I, 3J, L. About 14 (13–15) right somatic kineties, middle one longest, terminating anteriorly about one-sixth down the length of the body (Figs 2E, G–I, 3J, L; Table 1). Anterior of rightmost kinety terminating at one-third down length of cell, second rightmost kinety (RK n −1) extending to anterior and posterior ends of cell as a full kinety. Other right somatic kineties progressively shortened anteriorly towards dorsal and ventral margins to form two semi-sutures along dorsal full RK n −1 and PK2, respectively (Figs 2G–I, 3L). Left side sparsely ciliated, with six or seven kineties (including PK1; Fig. 2E, H; Table 1). Dorsal brush kinety consisting of dikinetids in anterior half of cell and monokinetids in posterior half (Fig. 2E). Leftmost left kinety (LK n) extending to anterior end of cell (Fig. 2E, H). Two perioral kineties (PKs), one either side of oral slit, both consisting of densely spaced dikinetids in anterior 30%, continuing posteriorly as a row of monokinetids (Fig. 2E, H)., Published as part of Zhang, Gongaote, Zhao, Yan, Chi, Yong, Warren, Alan, Pan, Hongbo & Song, Weibo, 2022, Updating the phylogeny and taxonomy of pleurostomatid ciliates (Protista: Ciliophora) with establishment of a new family, a new genus and two new species, pp. 105-123 in Zoological Journal of the Linnean Society 196 (1) on pages 108-110, DOI: 10.1093/zoolinnean/zlac028, http://zenodo.org/record/7035078

LOXOPHYLLUM APOCHLORELLIGERUM SP. NOV. (FIGS 4, 5; TABLE 1) Zoobank registration: urn: lsid: zoobank. org:act: 32A46325-B72C-4B1D-A5AA-44145403DBB3 aPerioral kinety 2 or perioral kineties 2–3 were included. bPerioral kinety 1 and dorsal brush kinety were included. cOut of 25 individuals of Loxophyllum apochlorelligerum sp. nov. only three had a single macronuclear nodule; and out of 17 individuals of Paralitonotus foissneri sp. nov. only one had a single macronuclear nodule. Abbreviations: CV, coefficient of variation (as a percentage); mean, arithmetic mean; N, number of specimens; SD, standard deviation. Diagnosis: Body lanceolate, about 170 – 280 µm × 35–50 µm in vivo; seven to nine left and 12–14 right somatic kineties; extrusomes clavate, distributed along entire cell margin; three to five inconspicuous dorsal warts located at anterior one-third of body; single subterminal contractile vacuole; two ovoidal macronuclear nodules and one micronucleus; freshwater habitat. Type material: A silver proteinate slide with the holotype specimen circled by ink and another two silver proteinate slides with paratype specimens deposited in the Laboratory of Protozoa, Ocean University of China, with registration numbers ZGAT2020051801-1 (holotype), ZGAT2020051801-2 and ZGAT2020051801-3. Type locality and ecological features: A boggy area in Weishan Lake (34°45′59.56″N, 117°09′22.65″E), Ji’ning, China. Water temperature 21 °C and pH 8.30. Etymology: Composite of the Greek adjective αΠό- (from) and the species-group name chlorelligerum (‘bearing chlorellae’, a green alga), indicating a ciliate similar to Loxophyllum chlorelligerum Vuxanovici, 1959. SSU rDNA sequence: The SSU rDNA sequence of Lo. apochlorelligerum sp. nov. has been deposited in the GenBank database, with length 1531 bp, G+C content 42.26% and accession number MW414675. The SSU rDNA gene sequence similarity between Lo. apochlorelligerum sp. nov. and its congeners ranges from 0.958 to 0.978 (Fig. 8). Description: Body lanceolate, slightly contractile, with a beak-like anterior end and a pointed posterior end. Cell size about 170–280 µm × 35–50 µm in vivo when fully extended. Neck region inconspicuous, occupying 25% of cell length, often with several inconspicuous dorsal warts (Fig. 4A, arrows). Cell typically with a thin, well-defined hyaline fringe (Fig. 5A, D, G). Right side densely ciliated; left side somewhat vaulted and sparsely ciliated. Two macronuclear nodules, elliptical in outline, about 15–23 µm × 10–15 µm in vivo, centrally located (Figs 4D, E, H, 5B, E, I; Table 1). Micronucleus positioned between macronuclear nodules (Figs 4H, 5I). Contractile vacuole subterminally located (Figs 4A, D, F, 5A, B, G), ~15–20 µm in diameter, pulsating about every 30 s. Extrusomes clavate, straight or slightly curved, ~5–7 µm long, distributed along entire cell margin and often clustered in anterior portion of dorsal margin to form three to fie warts (Figs 4A, D, J, 5C, F). Cortical granules tiny (, Published as part of Zhang, Gongaote, Zhao, Yan, Chi, Yong, Warren, Alan, Pan, Hongbo & Song, Weibo, 2022, Updating the phylogeny and taxonomy of pleurostomatid ciliates (Protista: Ciliophora) with establishment of a new family, a new genus and two new species, pp. 105-123 in Zoological Journal of the Linnean Society 196 (1) on pages 110-112, DOI: 10.1093/zoolinnean/zlac028, http://zenodo.org/record/7035078, {"references":["Vuxanovici A. 1959. Contributii la studiul unor infuzori holotrichi. Studii si Cercetari de Biologie Seria Biologie Animala 11: 307 - 335."]}

FAMILY PARALITONOTIDAE FAM. NOV. Zoobank registration: urn: lsid: zoobank. org:act: 4C15DF9C-2DD5-4D28-B442-0469353361AA Diagnosis: Slender Pleurostomatida with anterior part of right somatic kineties shortened and forming an unciliated region in each of the apical and subapical regions. Type genus: Paralitonotus (see below). Etymology: Composite of the stem of the name of the type genus and the family suffix -idae (see Articles 29.1 and 29.2 of the ICZN, 1999). Genera assigned: Apolitonotus Pan et al., 2020, Paralitonotus, Pseudolitonotus Wu et al., 2022. Remarks: According to Article 64 of the ICZN (1999), any included valid nominal genus can be chosen as the type genus, not necessarily that having the oldest name. We have chosen the new genus Paralitonotus as the type genus because its anteriorly shortened right kineties form the most conspicuous glabrous region on the right side, which is the main diagnostic character of the family.

KEY TO GENERA WITHIN THE ORDER PLEUROSTOMATIDA Based on previous reports (Wu et al., 2017; Pan et al., 2020) and the present work, a revised key to the genera is provided here: 1. Glabrous region in anterior of right side present …............................................................................. 2 Glabrous region in anterior of right side absent …............................................................................... 4 2. Leftmost left kinety (LK n ) terminates at anterior end of cell …........................................................... 3 Leftmost left kinety (LK) does not terminate at anterior end of cell...........................… Pseudolitonotus n 3. Right somatic kineties anteriorly shortened along rightmost full kineties …..................... Apolitonotus Right somatic kineties progressively shortened anteriorly from middle towards dorsal and ventral margins …............................................................................................................................ Paralitonotus 4. Middle right somatic kineties anteriorly shortened to form a suture …............................................. 5 Middle right somatic kineties not shortened to form a suture ….......................................................... 10 5. Middle right somatic kineties shortened posteriorly to form a suture …..................... Kentrophyllum Middle right somatic kineties not shortened posteriorly to form a suture.......................................... 6 6. Spoon-like excavation in anterior region present …........................................................ Amphileptiscus Spoon-like exca vation in anterior region absent…...................................................................................7 7. Left perioral kinety forming a circle …................................................................................... Opisthodon Left perioral kinety not forming a circ le ….................................................................................................8 8. Right and left perioral kineties do not cross and reach posterior of cell ….......................................... 9 Right and left perioral kineties cross and do not reach posterior end of cell …................ Apoamphileptus 9. Oral slit extends nearly to posterior end of cell …....................................................... Pseudoamphileptus Oral slit does not extend nearly to posterior end of cell …..................................................... Amphileptus 10. Right somatic kineties anteriorly shortened along rightmost full kineties ….................... Protolitonotus Right somatic kineties anteriorly shortened along perioral kinety.................................................... 11 11. Extrusomes absent along dorsal margin ….......................................................................................... 12 Extrusomes present along dorsal margin ….......................................................................................... 13 12. Spoon-like excavation present …................................................................................................ Acineria Spoon-like excavation absent …..............................................................................................., Litonotus 13. Without string-like oral bulge ….......................................................................................... Loxophyllum With string-like oral bulge…........................................................................................... Siroloxophyllum, Published as part of Zhang, Gongaote, Zhao, Yan, Chi, Yong, Warren, Alan, Pan, Hongbo & Song, Weibo, 2022, Updating the phylogeny and taxonomy of pleurostomatid ciliates (Protista: Ciliophora) with establishment of a new family, a new genus and two new species, pp. 105-123 in Zoological Journal of the Linnean Society 196 (1) on page 120, DOI: 10.1093/zoolinnean/zlac028, http://zenodo.org/record/7035078, {"references":["Wu L, Jiao X, Shen Z, Yi Z, Li J, Warren A, Lin X. 2017. New taxa refresh the phylogeny and classification of pleurostomatid ciliates (Ciliophora, Litostomatea). Zoologica Scripta 46: 245 - 253.","Pan H, Zhang Q, Dong J, Jiang J. 2020. Morphology and phylogeny of two novel pleurostomatids (Ciliophora, Litostomatea), establishing a new genus. Journal of Eukaryotic Microbiology 67: 252 - 262."]}

GENUS: APORTHOTROCHILIA GEN. NOV. Diagnosis: Dorsoventrally compressed Hartmannulidae with a podite; oral kineties reduced to two fragments; several kinetal fragments positioned on the right posterior of frontoventral kineties; postoral kineties strongly shortened posteriad; terminal fragments consisting of several parallel arranged fragments. Type species: Aporthotrochilia pulex (Deroux, 1976) comb. nov. (basionym: Trichopodiella pulex Deroux, 1976). Etymology: Composite of Greek prefix apo- (derived from) and the generic name Orthotrochilia; feminine gender. Comparison: In general, Aporthotrochilia gen. nov. resembles Orthotrochilia Song, 2003 in oral ciliature and the pattern of postoral kineties. However, the new genus can be distinguished by the presence of several extra kinetal fragments, i.e. the posterior fragments are on right posterior of frontoventral kineties and the higher number of terminal fragments (more than one vs. single) (Song, 2003). Compared with other closely related genera (e.g. Microxysma, Trochilioides, Chlamydonyx), Aporthotrochilia can be clearly identified by having two perioral kineties (vs. two circumoral and one preoral kineties), several terminal fragments (vs. single), and several extra kinety fragments caudally positioned on right of frontoventral kineties (vs. none) (Deroux, 1976c)., Published as part of Pan, Hongbo, Lin, Xiaofeng, Gong, Jun, Al-Rashied, Khaled A. S. & Song, Weibo, 2012, Taxonomy of five species of cyrtophorids (Protozoa: Ciliophora) including consideration of the phylogeny of two new genera, pp. 1-17 in Zoological Journal of the Linnean Society 164 (1) on page 6, DOI: 10.1111/j.1096-3642.2011.00751.x, http://zenodo.org/record/4890326, {"references":["Song W. 2003. On two marine cyrtophorid ciliates from China, with description of Chlamydonella derouxi nov. spec. and Orthotrochilia pilula (Deroux, 1976) nov. comb., and reestablishment of the genus Orthotrochilia nov. gen. (Protozoa, Ciliophora, Cyrtophorida). Hydrobiologia 499: 169 - 177.","Deroux G. 1976 c. Plan cortical des Cyrtophorida. III. - Les structures differenciatrices chez les Dysteriina. Protistologica 12: 505 - 538."]}

APORTHOTROCHILIA PULEX (DEROUX, 1976) COMB. NOV. (FIG. 3; TABLE 3) Basionym: Trichopodiella pulex Deroux, 1976. New diagnosis: Body oval in outline, size in vivo 25–40 ¥ 15–20 Mm; a small podite subterminally positioned; two contractile vacuoles situated on right side; one frontoventral kinety and three to five posterior fragments; nine to ten ventral kineties in postoral field; four to five terminal fragments; marine habitat. Slide deposition: One voucher slide with protargol specimens is deposited in the Natural History Museum, London, UK with registration number 2010:11:7:3. Another two slides are deposited in the Laboratory of Protozoology, Ocean University of China (no. PHB 09121509). All measurements in Mm. CV, coefficient of variation (%); FvK, frontoventral kineties; Ma, macronucleus; Max., maximum; Mean, arithmetic mean; Min., minimum; N, number of specimens; PF, posterior fragments; SD, standard deviation; SK, somatic kineties; TF, terminal fragments. Redescription: Body size about 25–40 ¥ 15–20 Mm in vivo; cells oval shaped with left margin sometimes slightly sigmoidal, both end bluntly rounded. Dorsoventrally flattened, ventral side flat and dorsal side slightly vaulted (Fig. 3A–E, I, N). Cytostome relatively small, subanteriorly positioned, nematodesmal rods hard to detect. Cytoplasm colourless or greyish, with several tiny, greasily shining granules (1–2 Mm across) and few food vacuoles (4–5 Mm across). Two contractile vacuoles (c. 3 Mm in diameter) positioned in anterior and posterior one-third near right margin (Fig. 3F, arrows). Podite inconspicuous, 4 Mm long, subterminally positioned (Fig. 3H, arrow). Macronucleus ellipsoid, positioned in body centre, heteromerous. Micronucleus not detected. Cilia about 6 Mm long. Movement by slowly gliding on substrate. Infraciliature as shown in Figure 3G, J, K, L, M, P–T. The short three to five right-most of the ventral kineties, which are anteriorly shortened progressively from left to right and posteriorly positioned, forming posterior fragments (PFs); the longest PF only extending forward to anterior one-third of body length (Fig. 3M, P, R). One frontoventral kinety (FvK) positioned next to PF extending apically. Both FvK and PF terminating posteriorly at the same level, and basal bodies densely arranged at their posterior ends (Fig. 3R, arrowheads). Nine to ten ventral kineties postorally positioned, strongly shortened from right to left. Terminal fragments consisting of four to five fragments (Fig. 3G, Q). Equatorial fragment not detected. Perioral kineties positioned anterior to cytostome, consisting of two fragments, both distinctly separated and composed of dikinetids. Morphogenesis: Only two specimens in middle and late stages of the morphogenetic process have been observed (Fig. 3K, L, S, T). These showed that (1) perioral kineties of opisthe were developed from the oral primordium in midbody, which is generated from sections of postoral kineties; (2) the posterior fragments of both proter and opisthe stem from the parental posterior fragments. Remarks: Deroux (1976c) described a species under the name of Trichopodiella pulex with its infraciliature (Fig. 3O) in detail: one frontoventral kinety, 11 postoral kineties and three or four posterior fragments; the postoral kineties strongly shortened. However, he did not note whether the podite is present. Our isolate corresponds very well to the original report in terms of infraciliature, except for the only difference in the number of postoral kineties (ten vs. 11), which is, however, considered minor. Therefore, our isolate should represent a population of Trichopodiella pulex. However, during our study, we found this organism was quite different from other Trichopodiella spp. by: the presence of podite (vs. absence), four to five terminal fragments (vs. single), three to five distinct posterior fragments (vs. none) and two perioral kineties (vs. single) (Fauré-Fremiet, 1957; Deroux & Dragesco, 1968; Deroux, 1976c; Gong et al., 2008). Therefore, we concluded that this small species should represent a distinct genus, and assigned it to the new genus Aporthotrochilia as Aporthotrochilia pulex (Deroux, 1976) gen. et comb. nov.

Pan, Hongbo, Lin, Xiaofeng, Gong, Jun, Al-Rashied, Khaled A. S., Song, Weibo (2012): Taxonomy of five species of cyrtophorids (Protozoa: Ciliophora) including consideration of the phylogeny of two new genera. Zoological Journal of the Linnean Society 164 (1): 1-17, DOI: 10.1111/j.1096-3642.2011.00751.x, URL: http://dx.doi.org/10.1111/j.1096-3642.2011.00751.x