taxonID	type	description	language	source
F65487889905FF9AFF33FB797164F891.taxon	description	(Figs 2 – 5, 7, 8; Tables 1 – 5, 7)	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	diagnosis	Diagnosis	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	materials_examined	Material examined Altogether, 705 specimens of Trematosoma husselae sp. nov. were studied on its basibionts Setaphyes kielensis and S. dentatus (Kinorhyncha), of these 308 specimens by light microscopy and 397 specimens by SEM. The basibionts were deposited at the Museum für Naturkunde Berlin in the collection " Vermes " under the catalogue numbers ZMB 12294 – 12313, 12359 – 12418, and 12454 – 12514. The holotype represents the specimen with a swarmer ventrally on segment 1 of the basibiont ZMB 12499. All light microscopical epibionts on the basibiont S. kielensis ZMB 12479 – 12505 represent paratypes. For collecting details see Table 1. Type locality Intertidal mud at Kampen, east coast of the island of Sylt, German Bight, North Sea, 54 ° 57 ’ 15 ” N, 008 ° 21 ’ 34 ” E, precision 50 m. Type basibiont Setaphyes kielensis (Zelinka, 1928), Kinorhyncha, Pycnophyidae Additional basibiont Setaphyes dentatus (Reinhard, 1881), Kinorhyncha, Pycnophyidae	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	etymology	Etymology The species is named after Birgit Hussel, previously technician at the Litoralstation Sylt, in recognition of her help to B. N. and H. Y. with collecting the specimens and her engagement over many years in sending meiofauna samples from Sylt to the first author for his public outreach activities in Germany and Sweden during the 2000 s.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	diagnosis	Diagnosis Acinetid with calyciform, dorso-ventrally compressed lorica of about 35 µm x 30 µm size, short stalk with internal longitudinal striae, one left and one right row of tentacles ca. 5 µm long, tentacles separated by small gap, epibiontic on pycnophyid Kinorhyncha.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	description	Description Specimens of Trematosoma husselae sp. nov. sat on a short stalk and revealed a calyciform, dorso-ventrally compressed lorica (lorica holotype: 37 µm length x 31 µm width; range 30 – 47 µm x 26 – 34 µm, thickness 9 – 16 µm) with the zooid (Figs 2, 3, 4 B – F, 5 A – C, 7, 8, 10 C). The zooid usually filled the lorica except for a small basal cavity (Figs 2, 4 D, F, 5 B, L). The stalk (length 5 – 7 µm, width 3 – 4 µm) contained few longitudinal striations recognisable only in favourable light microscopical specimens (Figs 4 F, 5 G). The apical edge appeared more pronounced in SEM mounts and sometimes more rounded in light microscopical preparations depending on the degree of flattening on the slide (comp. Figs 3, 7 and 8 with Figs 2 A, 4 B – F and 5 A). The surface of the lorica showed slightly elevated circular rings at irregular intervals around the body in SEM (Figs 3 D, 8 A). In optical section, the lorica wall appeared much thicker (about 4 µm) in its basal two thirds than apically (Figs 2, 4 C – F). The tentacles (length 4 – 6 µm) could be withdrawn, and the terminal end of the lorica revealed a cleft (Figs 2 B, 3 G, 4 A). The tentacles occurred in one left and one right row separated by a small gap on one of the broader sides of the zooid (Figs 2, 4 C), but seemed sometimes to form a single row of tentacles (Figs 3, 4 E, 7 B, 8). An epibiont exhibited 8 – 16 tentacles in each row (Figs 2, 3 C – F, 4 C, E, F, 8 A). Each capitate tentacle terminated in a small blunt knob with a minute central depression (Figs 2, 3 D – F, 4 C). Occasionally, empty shells of T. husselae sp. nov. were found (ZMB 12462, 12488; Fig. 4 A). Specimens of Trematosoma husselae sp. nov. possessed usually one central spherical macronucleus and occasionally a more ovoid macronucleus or two spherical macronuclei, which did not fuse at a different focal level (ZMB 12499; Fig. 5 C). In many cases, no micronuclei could be observed, but often 2 – 7 spherical micronuclei of the same yellowish colour as the macronucleus were found (e. g., ZMB 12479, 12480, 12500; Figs 2, 4 C, D). A contractile vacuole? may appear apically in an epibiont, but could only be traced in few specimens, possibly because of insufficient conservation. Eleven epibionts harboured a single, inner, ovoid structure covered by two membranes, with a nucleus (ZMB 12365, 12397, 12489, 12492, 12498, 12499, 12500; Figs 4 D, 5 B; 13 – 15 µm x 8 – 10 µm). This ovoid structure was interpreted as a developing swarmer. Trematosoma husselae sp. nov. seemed to develop from a significantly smaller spherical stage (Fig. 5 D, E; 12 µm x 10 µm) with a minimum of about four tentacles and a short stalk (3 µm x 2 µm) via small calyciform and laterally compressed stages to much larger calyciform and laterally compressed specimens with up to 25 tentales (comp. Fig. 4 C – F with Fig. 5 D, E). One young attached specimen (16 µm x 13 µm) seems to possess parallel rows of surface structures (Fig. 5 F). A small spherical structure with one macronucleus and two micronuclei seemed to be held by the tentacles of a specimen of T. husselae sp. nov. (ZMB 12492; Fig. 4 E). This was interpreted as a swarmer recently born from its trophont. On one specimen on S. dentatus, a small spherical Trematosoma husselae sp. nov. with few tentacles appeared inside the empty shell of a larger empty lorica (ZMB 12503; Fig. 5 G). This specimen was probably re-arranged during mounting of the slide and is regarded as an artefact. In specimens collected 1998, the cytoplasm was often found withdrawn from the base to the apical part of the lorica and revealed almost no substructures except the macronucleus and micronuclei; tentacles could usually not be traced (Fig. 5 M). This situation is interpreted as a fixation artefact. Few specimens were preserved more satisfyingly similar to the ones collected 2016, e. g., specimens on ZMB 12397 and 12399 (Fig. 5 L).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889905FF9AFF33FB797164F891.taxon	diagnosis	All species of Trematosoma possessed a compressed lorica or zooid and tentacles arranged in rows and originating from a fold, the latter characters beeing regarded as genus-specific (Batisse 1972; Jankowski 1978; Curds 1985; Dovgal 2002). The compressed body was not totally clear for T. ovata (Pritchard, 1852) because of the insufficient description of the species (Alder 1851; Pritchard 1852). Trematosoma husselae sp. nov. agreed with T. amphiasci (Precht, 1935) and T. pusilla (Maupas, 1881) in the calyciform shape of the lorica and with most species in the general size of the body except for the much larger T. constricta (Collin, 1909) and T. pusilla (Table 7). Measurements of length and width of stalks were missing in several species, so only a more general statement can be given about this organ. The new species could be distinguished from T. amphiasci, T. complatana (Gruber, 1884), T. constricta, T. falcata (Jankowski, 1981), T. ovata, and T. pusilla by the short length of its stalk and agreed with T. bocqueti (Guilcher, 1950) and T. rotunda (Allgén, 1951) in this character (Table 7). Longitudinal striae were reported for the stalk of T. constricta and T. husselae sp. nov., transversal striae for T. rotunda, whereas information about these characters was missing for the remaining species (Table 7). A basal disc was mentioned for T. bocqueti and T. falcata but did not seem to exist in T. husselae sp. nov. (Table 7; Batisse 1972; Jankowski 1981; this paper). Tentacles were arranged in all species in a row with a broad central gap in T. complatana, a small or a broad gap in the Australian population of T. bocqueti, and a small gap in all remaining species except T. ovata and T. pusilla, for which information was limited in this respect. Tentacles occurred also laterally in T. complatana and in the Australian population of T. bocqueti, but not in any other species of the genus. Trematosoma husselae sp. nov. agreed with most species in the number of tentacles from 8 – 16 on, but T. falcata and T. pusilla had only 4 – 6 tentacles (Table 7). Short tentacles of up to about 10 µm length were reported for T. amphiasci, T. bocqueti, T. falcata, T. pusilla, T. rotunda, and T. husselae sp. nov., whereas much longer tentacles appeared in T. complatana and T. constricta; T. amphiasci and T. bocqueti possessed both short and long tentacles (Table 7).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	description	(Figs 5 J, 6 – 9; Tables 1, 3, 4, 6)	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	materials_examined	Material examined In total, 14 specimens of Cothurnia buetschlii were found on five males of Setaphyes kielensis mounted for light microscopy and an one female and one male of the same species mounted for SEM: All specimens were collected 2016, and the basibiont S. kielensis deposited at the Museum für Naturkunde Berlin in the collection " Vermes " under the catalogue numbers ZMB 12468, 12474, 12486 – 12489, and 12499. For collecting details see Table 1.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	diagnosis	Emended diagnosis Vaginicolid with bulbous lorica basally and narrowing anteriorly, lorica slightly dorso-ventrally compressed with anterior margin recessing on opposing sides laterally, short stalk of about 10 µm, stalk and endostyle with internal longitudinal striae, mesostyle lacking, zooid with weak circular annulation, C-shaped or serpentine macronucleus orientated longitudinally in periphery of zooid, epibiontic on pycnophyid Kinorhyncha.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	description	Description The zooid was withdrawn into its lorica in all 14 specimens except one (Fig. 5 J). The kinorhynchs exhibited also numerous suctorian ciliates (Figs 7, 8, 9 A; Tables 3, 4). Each lorica with its bulbous posterior end was slightly dorso-ventrally compressed and contained a single zooid (Figs 6, 7, 9). An operculum or a valve was missing. The lorica measured 46 – 58 µm in length, 21 – 23 µm at its largest diameter, and 10 – 19 µm at its aperture (Table 6). Basally, the lorica wall thickened slightly with distinct outer and inner borders depending on the angle of the specimen to the DIC prisms (Fig. 9 D, E, white and black arrows). A lorica attached to the cuticle of a kinorhynch with a short stalk (Fig. 9 D – G). The anterior margin of a lorica recessed on opposing sides laterally (Figs 6, 7). The surface of the lorica appeared smooth in SEM but was sometimes covered with detritus (Figs 7, 8; ZMB 12489). In two specimens, epibiontic filamentous bacteria grew on the lorica (Fig. 8 B). The withdrawn zooid reached a length of 22 – 37 µm and revealed a weak circular annulation on its outside around its entire body (ZMB 12486 – 12489; Figs 6, 9 C, D; Table 6). The external stalk showed conspicuous, internal, longitudinal striae continuing into the endostyle and attached to the cuticle of the basibiont with a kind of cement with an almost central pore (ZMB 12486 – 12489; Figs 6, 9 D – G). An endostyle with longitudinal striae extended between the base of the lorica and the zooid, a mesostyle was missing (ZMB 12486, 12489; Figs 6, 9 D – F). The considerably elongated, more or less C-shaped or serpentine macronucleus meandered longitudinally in the periphery of the zooid and reached a length of up to 30 µm (ZMB 12486 – 12489; Figs 6, 9 E – G; Table 6). One or at least five micronuclei were observed (ZMB 12486; Figs 6, 9 E – G). A large spherical cavity seemed to occur below the infundibulum at the anterior end of the zooid and may or may not represent a contractile vacuole (ZMB 12486; Figs 6, 9 G). No information became available about the peristomial lip and disc because of the withdrawn zooids. Peristomal cilia may appear as a row of bristle-like projections at the anterior end of the withdrawn zooid (ZMB 12486, 12489; Fig. 9 B). A single specimen with an extended zooid occurred ventrally on segment 10 of one basibiont of S. kielensis (ZMB 12486; Fig. 5 J, right specimen). The zooid (51 µm x 16 µm) exhibited a basal attachment area with longitudinal striae, a long endostyle (ca. 18 µm x 2 – 5 µm) not clearly separated from the zooid apically, a large serpentine macronucleus (15 µm x 4 µm), and anteriorly a large spherical structure (13 µm x 8 µm), possibly a contractile vacuole (Fig. 5 J). The endostyle did not show any longitudinal striae but a kind of inner annulation, which was regarded as a fixation artefact.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	diagnosis	Zelinka (1914, p. 680 – 682) described Cothurnia buetschlii inadvertently as a new species by mentioning several morphological characters and providing measurements for the lorica (53 µm x 21 µm) and stalk (length 10 µm). In his monograph, Zelinka (1928, pp. 194, 195, text figs 37 a, b, figs 9, 10 in pl. 7, fig. 8 in pl. 14) provided much more detailed information about the epibiont: He found up to 10 or more specimens of C. buetschlii on adult but also on juvenile specimens of Pycnophyes communis and other, unnamed species of Kinorhyncha, mainly on the ventral side of the trunk or on the lateral terminal spines. The lorica (53.1 µm x 21 µm, 19.2 µm at aperture) appeared recessed on two opposing sites. The stalk (8.5 – 12.6 µm x 5.3 µm) showed an internal longitudinal striation and a striated endostyle (Zelinka 1928, text fig. 37 a; the very weak striation is only recognisable in the original book but not necessarily in xerocopies). The contracted zooid reached a length of 27.7 µm. The macronucleus was C-shaped and extended in longitudinal direction (Zelinka 1928, text figs 37 a) but was mentioned by Zelinka (1928, p. 197) as “ quergestellt ” (= transversely oriented). Measurement data of the inadvertent original description (Zelinka 1928) differed slightly from those of his intended species description (Zelinka 1928), the latter being more precise, and also from those given by Warren and Paynter (1991, pp. 21, 22, 29, figs 47, 48: lorica 53.2 µm x 27 µm, stalk 10 µm x 4 µm). Their descriptive text disagreed from their identification key in that the mesostyle was stated to be absent and an endostyle to be present, whereas the identification key stated the opposite. The latter was erroneous, because it did not agree with Zelinka’s (1928) description and with our observations. All observations of Zelinka (1914, 1928) were based on living specimens of C. buetschlii, but the zooids never raised above the lorica, so not all characters became available for study. Our preserved specimens of C. buetschlii agreed with Zelinka’s (1914, 1928) descriptions in the sizes of the lorica, stalk, and length of the zooid (Table 6), the shape of the lorica with two opposite recessed anterior sides (Figs 7, 8), the existence of an endostyle, the longitudinal striae in both the stalk and endostyle (Figs 6, 9 D – F), and the longitudinal, C-shaped macronucleus (Figs 6, 9 E – G). Our observations of a weak surface annulation of the zooid (Figs 6, 9 C) was not reported by Zelinka (1914, 1928) but may have been overlooked by him. Referrence to C. buetschlii in the literature was rare. Besides the review of species of Cothurnia by Warren and Paynter (1991), Kahl (1933, p. 138) mentioned C. buetschlii briefly and erroneously cited the species as C. buetschlii Zelinka, 1885. It remains a bit mysterious why Kahl claimed that one of the broader sides of a specimen would be longer than the opposite side and would cover elastically the opening (Kahl 1935, p. 780, fig. 143.35 – 35 a). This was not reported by Zelinka (1914, 1928) at all and could not be confirmed by us as well. To our knowledge C. buetschlii has not been mentioned otherwise and was not redescribed, yet.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788990FFF82FF33FA8E74FCFC82.taxon	distribution	Zelinka (1928) reported C. buetschlii from Pycnophyes communis and also from similar species of Kinorhyncha without providing their species names. The distribution areas of the basibiont P. communis and of the here reported Setaphyes dentatus and S. kielensis overlap widely (Fig. 1). Whereas P. communis was reported from the Skagerrak, Baltic Sea, North Sea, Irish Sea, Mediterranean Sea, and Black Sea, S. dentatus was mentioned from the Baltic Sea, North Sea, Irish Sea, Mediterranean Sea, and Black Sea, and S. kielensis showed records from the White Sea, Baltic Sea, North Sea, British Channel, and Black Sea (Fig. 1; González-Casarrubios et al. 2023; Neuhaus 2023 a – c). With this overlap of distribution areas it is highly likely that an exchange of epibionts between P. communis, S. dentatus, and S. kielensis would be possible.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889912FF86FF33FB4474BAFF6E.taxon	description	In the material collected in May 1998, 27 out of 69 specimens of Setyphyes kielensis (= 39 %) were infested by 106 specimens of Trematosoma husselae sp. nov. (Table 2). A kinorhynch hosted 1 – 15 specimens of suctorian ciliates, on average 4 specimens (Table 2). The vast majority occurred on the ventral side of the basibionts (80 %): the rate attached to the ventral side of basibionts was particularly high on segment 1 (19 % of all attached T. husselae sp. nov.), segment 3 (12 %), and on segments 8 and 9 (8 – 9 %). Neither Cothurnia buetschlii nor filamentous bacteria were found on the kinorhynchs collected in 1998. In the material collected in June 2016, 202 specimens of Trematosoma husselae sp. nov. were found on 20 out of 23 S. kielensis mounted for light microscopy and 397 ciliates on 21 specimens mounted for SEM, in total 599 specimens (Tables 3, 4). It should be kept in mind that the kinorhynchs were mounted with one side (usually the lateral side) on the SEM stub, so potential epibionts on this side could not be observed, and the number of epibionts might be slightly higher (Table 3). One kinorhynch revealed no epibionts (ZMB 12455, SEM). It was extremely dirty and may have been dead at the time of collecting, therefore, it was excluded from the further analysis. A kinorhynch collected in June 2016 hosted 1 – 43 specimens of Trematosoma husselae sp. nov., on average 15 specimens (Tables 3, 4). Most epibionts concentrated on the ventral side of their basibionts (82 %) and here especially on segment 1 (17 % of basibionts) and on segments 8 – 10 (11 – 13 %; Tables 3, 4). Only 5 % of T. husselae sp. nov. occurred on segment 2, whereas the remaining segments revealed a balanced distribution of 7 – 9 %. A single suctorian epibiont was found on segment 11 of a single kinorhynch. Nine specimens of Cothurnia buetschlii were found on five S. kielensis out of 24 specimens mounted for light microscopy and five specimens on two kinorhynchs out of 21 specimens mounted for SEM (ZMB 12486 – 12489, 12468, 12499; Figs 7 – 9; Tables 3, 4). Filamentous prokaryote epibionts occurred in 18 out of 42 specimens of S. kielensis, not all of them carrying ciliate epibionts (Tables 3, 4). A species of coccoid prokaryotes arranged in a row was traced only once (ZMB 12486; Fig. 5 J; Table 4).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889916FF86FF33FEFC76BEFD38.taxon	description	No ciliate epibionts or filamentous bacteria were noticed on the specimens collected 1988 and 1998. Altogether, 27 specimens of Trematosoma husselae sp. nov. were noted on three out of 13 specimens of S. dentatus collected in June 2016. One kinorhynch hosted 2, 3, or 22 epibionts (Table 5). One specimen also revealed filamentous prokaryotic epibionts (Table 5). No specimens of C. buetschlii were traced on any of the 14 specimens of S. dentatus collected 2016. ex	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889916FF8AFF33F9937438FDAA.taxon	diagnosis	Diagnostic characters of Trematosoma and Limnoricus Jankowski, 1981. The taxonomy of acinetid Suctoria is quite confusing and species with similar characters like a flattened lorica and one to few rows of tentacles have been grouped in different genera, viz Trematosoma and Limnoricus (see Jankowski 1981; Dovgal 2002; Dovgal et al. 2008; Dovgal & Lozowskiy 2008). Species of Trematosoma, Limnoricus ceter Jankowski, 1981, and L. seticolus (Jankowski, 1981) possessed a stalk separated from the lorica, whereas L. ponticus Dovgal & Lozorowskiy, 2008 showed a thecostyle with the lorica gradually diminishing in diameter to the basis (Pritchard 1852; Maupas 1881; Gruber 1884; Collin 1909; Precht 1935; Guilcher 1950; Allgén 1951; Jankowski 1981; Dovgal & Lozorowskiy 2008; this paper). Based on this observation, Dovgal et al. (2008) discussed placing L. ponticus in a different genus but refrained from this. The differences between L. ceter, L. seticolus, and species of Trematosoma appear to be more species-specific than genus-specific, and at some stage L. ceter and L. seticolus may have to be transferred to Trematosoma. TABLE 7. (Continued) One more distinctive genus-specific character might be the reproduction via semi-circumvaginative budding in L. ponticus versus internal budding in T. bocqueti, T. constricta, T. pusilla, and T. husselae sp. nov.; however, reproduction in L. ceter and L. seticolus is unknown, semi-circumvaginative budding may represent a character of L. ponticus only (Table 7; Maupas 1881; Collin 1912; Batisse 1972, 1975; Jankowski 1981; Curds 1985; Dovgal et al. 2008; Dovgal & Lozowskiy 2008; this paper). The differing types of budding within Suctoria were used by Batisse (1975) to justify new taxonomic categories. These types of reproduction were mainly based on cultivated species allowing in-depth studies. Unfortunately, such detailed information is lacking for almost all species of Limnoricus and Trematosoma. Although we had quite a large amount of specimens of T. husselae sp. nov. available, we noticed only swarmers inside the zooid and a swarmer, which seemed to have left its parent (comp. Figs 2 A, 4 D, and 5 A, B with Fig. 4 E). The image provided for L. ponticus about semi-circumvaginal budding did not allow to see that character clearly, so we relied on the statements of the authors (Dovgal et al. 2008, fig. 2 B; Dovgal & Lozowskiy 2008, fig. 2).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788991AFF8AFF63FAE8777BF892.taxon	description	Küsters (1974) reported four species of Acinetidae collected at Königshafen in the northern part of Sylt in 1969 and 1970 from experimentally exposed artificial substrates, viz, Acineta compressa Claparède & Lachmann, 1858, A. foetida Maupas, 1881, A. tuberosa (Ehrenberg, 1834), and Loricophrya tuba. These species mentioned by Küsters (1974) did not occur on our kinorhynch specimens of Setaphyes kielensis collected at Königshafen in 1998 or on S. dentatus and S. kielensis collected at Kampen in 1988 and 2016, but a different species, viz, Trematosoma husselae sp. nov. was found 1998 and 2016 at Kampen but not at Königshafen at any time (Tables 1 – 4; Küsters 1974). A suctorian species on the same basibionts and from the same location as in this study was briefly reported before by Neuhaus (2013, p. 331: “ Suctoria, possibly Acineta sp., are also common ectocommensals on Pycnophyes dentatus and P. kielensis from intertidal mudflats in northern Germany; few to several specimens attach to any free area on the trunk cuticle (Fig. 5.8.1 D, E; Neuhaus own obs.) ”). It turned out that the identification of the epibiont at that time was erroneous, and we here assign the species to Trematosoma husselae sp. nov.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F6548788991AFF89FF63F8B8745AFE1E.taxon	description	Zelinka (1914) described inadvertently the epibiontic Loricophrya tuba on Kinorhyncha from the Gulf of Trieste, because he mentioned the species's name in connection with identifying morphological characters. A more substantial description, the species name of the basibiont of this epibiont, Pycnophyes communis, and the record of Flectacineta livadiana? followed in his monograph (Zelinka 1928). Adrianov and Higgins (1996, fig. 23) labelled two epibionts of Pycophyes parasanjuanensis as “ ectocommensal suctorians ”, but these specimens represented a species of Cothurnia and not a suctorian. Dovgal et al. (2008) reported Limnoricus ponticus from an unidentified Indian species of Pycnophyes. Together with the new species reported in this article, four acinetid species are now known to settle on pycnophyid Kinorhyncha in European and Indian waters. Trematosoma husselae sp. nov. was here reported from species of Kinorhyncha, but few other species of Trematosoma were known to settle on meiofauna, viz, T. amphiasci, T. bocqueti, and T. pusilla on Coepepoda, and T. rotunda on Nematoda (Precht 1935; Guilcher 1950; Allgén 1951; Fernandez-Leborans et al. 2012; Chatterjee et al. 2020, 2022).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889919FF89FF63F9EC77A5F8E6.taxon	description	Küsters (1974) reported 11 species of Vaginicolidae collected at Königshafen in the northern part of Sylt in 1969 and 1970 from experimentally exposed artificial substrates, viz, Cyclodonta bipartita (Stokes, 1885) Matthes, 1958, Cothurnia angusta Kahl, 1933, C. ceramicola Kahl, 1933, C. coarctata Kahl, 1933, C. curvula (Entz, 1876) Entz, 1884, C. cypridicola Kahl, 1933, C. innata O. F. Müller, 1786, C. inflata Stokes, 1893, C. maritima Ehrenberg, 1838, C. nodosa Claparède & Lachmann, 1858, and C. pedunculata Dons, 1918. We did not find any of these species of Cothurnia on our kinorhynch specimens of Setaphyes kielensis collected at Königshafen in 1998 or on S. dentatus and S. kielensis collected at Kampen in 1988 and 2016 but a different species, viz, C. buetschlii (Tables 3, 4).	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
F65487889918FF88FF63FED87634FC82.taxon	description	The literature revealed four reports of species of Cothurnia on Kinorhyncha in addition to C. buetschlii. Adrianov and Higgins (1996, fig. 23) labelled two “ ectocommensal suctorians ” attached ventrally to segment 1 of Pycnophyes parasanjuanensis, but these epibionts can be identifyed as a species of Cothurnia. Ostmann et al. (2012, pp. 87, 90 fig. 6) documented a species of Cothurnia from Echinoderes applicitus. The specimens in the collection of the Museum für Naturkunde Berlin revealed not too many details because of the insufficient conservation in the mounting medium Fluoromount G, but they were clearly different from C. buetschlii. Neuhaus (2013, p. 331) mentioned “ sessile ciliates, possibly a species of Cothurnia, […] on Pycnophyes sp. from Florida (Fig. 5.8.1 A, B) ”. These were based on life observations and photographs. Last not least, Cepeda et al. (2022 c, fig. 4 H, I) provided SEM images of Leiocanthus quinquenudus with epibionts similar to C. buetschlii with respect to the general shape of the lorica but with an asymmetrical opening. The limited amount of observations does currently not allow to draw any further-reaching conclusions about infestation of Kinorhyncha by species of Cothurnia.	en	Neuhaus, Birger, Lu, Borong, Yamasaki, Hiroshi, González-Casarrubios, Alberto (2023): Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae). Zootaxa 5343 (5): 439-470, DOI: 10.11646/zootaxa.5343.5.2, URL: https://www.mapress.com/zt/article/download/zootaxa.5343.5.2/51843
