Setaphyes kielensis (Zelinka, 1928)

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), pp. 439-470 : 456-460

Infestation of Setaphyes kielensis

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. 5J ; Table 4 ) .

Figures

FIGURE 5. Setaphyes kielensis (A, ZMB 12489; B, ZMB 12500; C, ZMB 12499; D, ZMB 12487; J, ZMB 12486; L, ZMB 12397; M, ZMB 12369) and S. dentatus (E–G, K, ZMB 12503; F, H, I, ZMB 12494) with specimens of Trematosoma husselae sp. nov. (A–G, J–M), Cothurnia buetschlii (J), and a case of fungus or developmental artefact (H, I, ZMB 12494), DIC. A. Segments 1–4, lateral and dorso-ventral view on the calyciform, dorso-ventrally compressed lorica with the zooid, ventrolateral view on basibiont. B. Epibiont with swarmer, stalk, and lorica in optical section. C. Epibiont with two macronuclei not fusing at any focal level. D, E. Young, small, spherical epibionts with few tentacles, not all tentacles in focus. F. Young specimen on cuticle of basibiont with striation pattern on surface (arrows). G. Epibiont with tentacles in empty shell of suctorian epibiont. H, I. Segment 10, dorsally (H) and optical section (I), subcuticular fungus or internal sclerotisation artefact of the cuticle (arrows). J. Assemblage of epibionts on segment 10 of basibiont with C. buetschlii (contracted specimen left, extended specimen right), T. husselae sp. nov., and two kinds of filamentous bacteria. Arrows mark endostyle. K. Suctorian on segment 7 of S. dentatus. L, M. Specimens collected 1998, showing cellular substructures (L) and withdrawn zooid with minimum amount of cellular substructures (M). Extended focus images of six (D), eight (H, L), and three (K) images. Arrowheads mark stalks in B, D, E, G, and J. Abbreviations: ba, bacteria; ca, basal cavity in lorica; co, C. buetschlii; en, endostyle; lo, lorica; ma, macronucleus; s, segment, followed by segment number; sc, spherical cavity; sp, sperm; st, stalk; su, suctorian epibiont; sw, swarmer; te, tentacle; tu, tube on segment 2. Scale bar in A 50 µm, in B 20 µm, valid for B, G–J and M, in C 20 µm, valid for C, K, and L, and in D–F 10 µm.

FIGURE 7. Setaphyes kielensis (ZMB 12468) with epibionts, SEM. A. Segments 1–11, ventral-right. B. Segments 4–8, ventral view. Arrows mark laterally recessed anterior margin of lorica of Cothurnia buetschlii. Abbreviations: co, Cothurnia buetschlii; fp, filamentous prokaryotes; lts, lateral terminal spine; s, segment, followed by segment number; se, seta; su, suctorian epibiont; tu, tube. Scale bar in A 100 µm and in B 20 µm.

FIGURE 8. Setaphyes kielensis (A, ZMB 12468; B, ZMB 12474) with epibionts, SEM. A. Segment 6, left side. Arrow marks laterally recessed anterior margin of lorica of Cothurnia buetschlii. B. Segments 8–10, dorsal view.Abbreviations: co, Cothurnia buetschlii; fp, filamentous prokaryotes; s, segment, followed by segment number; su, suctorian epibiont; te, tentacles. Scale bar in A 10 µm and in B 20 µm.

FIGURE 9. Setaphyes kielensis (ZMB 12486), segment 10 with Cothurnia buetschlii (specimens 1–4), ventral view. A. Overview of position of epibionts. Numbers indicate specimens of C. buetschlii (comp. also Table 6). B–G. Specimens 3 (B) and 4 (C–G), images 8 (C), 15 (D), 19 (E), 24 (F) and 28 (G) showing surface annulation of zooid (C, D), internal longitudinal striae of stalk and endostyle (D–F), and attachment site of stalk to the cuticle of the basibiont (G, arrowheads). Note elongate macronucleus and numerous micronuclei (E–G). White arrows (D, E) mark basal outer margin of lorica, black arrows (D, E) point to bottom margin of lorica. Abbreviations: an, annulation on surface of zooid; ci, ciliae; en, endostyle; in, withdrawn infundibulum; lo, lorica; lts, lateral terminal spine; ma, macronucleus; mi, micronucleus; ps, penile spine; sc, spherical cavity; st, stalk; su, suctorian epibiont; zo, zooid. Scale bar in A 50 µm and in D 20 µm, valid for B–G.

Tables

TABLE 3. Number of Trematosoma husselae sp. nov. and Cothurnia buetschlii (indicated by C.) on the trunk segments of adult Setaphyes kielensis, SEM specimens, collected 2016. Abbreviations: *, attachment site of a detached suctorian or Cothurnia-like ciliate, not counted; *?, attachment site questionable, not counted; C.:, Cothurnia buetschlii; d, dorsal; fil. epib., filamentous prokaryotic epibionts; Totalsuctorians, total amount of suctorians; v, ventral.

Basibiont, sex Segment	ZMB 12454 ♀ / ♁?	ZMB 12456 ♀	ZMB 12457 ♁	ZMB 12458 ♁	ZMB 12460 ♀	ZMB 12461 ♁	ZMB 12462 ♁	ZMB 12463 ♁	ZMB 12464 ♀	ZMB 12465 ♀	ZMB 12467 ♀	ZMB 12468 ♁	ZMB 12469 ♀	ZMB 12470 ♁	ZMB 12471 ♀	ZMB 12472 ♁	ZMB 12474 ♀	ZMB 12475 ♀	ZMB 12476 ♀	ZMB 12477 ♁	ZMB 12478 ♀
1	3v, 2d	2v, 1d	5v, 1d	2v, 1+2*d	1+1*v		5v	2v, 1d		5v, 1+1*d	1*v	2v, 1*d	4v, 1d	2v, 3d	1v	2v	1+2*?v, 2+3*?d	3+1*v, 2+1*d	2v	2v	5v, 3d
2	2v	1v	2v	2v, 1*d								1v, 1d	2v	2v, 1d	2v		1v, 1*d	4v	2v	2v, 1*?d
3	1v		1v	3v			1v		3v, 1d	1v, 1d		1v; C.: 1v				5v	1v	2v	1v, 1d	2v, 1*?d	3v, 1d
4	1v	2v		1v					2v, 1d			2v, 2d		2v	2v	1v	1d	3v		4v	2v, 1d
5	2v	1v	1v	1v			1v	1d	1v	1v		1v, 2d; C.: 1v		2v	2v	1v	1v	6v	1v, 1d	2v	2v
6	4v	1*v	2v	1v	2v	1v	1v		2v	1v, 1d		3v; C.: 1v	1v	2v	3v		1v, 1d	5v	3v	2v	3v
7	1v		3v	2v			1v	1v	3v, 2d		1v	1v; C.: 1v		1v		1v	1v, 3d	2v	4v
8	4v		3v	4v	1v, 2d			2v	5v	1v, 1d		3v		2v	2v	3v	2d	6v	3v, 3d	1d	2v
9	1v	1v	2v	2v			1v	1v	5v, 4d	2v, 5d		3v	1d	1v	3v, 4d	1v, 1d	1v, 1d	7v, 1d	1v	1v	2v, 2d
10	1v	1v	3v	1v			4v		5v, 2d	2d		3v		4v	4v, 3d		2v; C.: 1d	2d	2v	1v	3v, 6d
Total suctorians	22	9	23	20	6	1	14	8	36	22	1	25	9	22	26	15	19	43	24	17	35
Remarks		sperma- tophore	fil. epib.	fil. epib.	dirty, fil. epib.			fil. epib.		dirty	sperma- tophore	fil. epib., C. buetschlii			dirty	dirty	fil. epib., C. buetschlii	dirty	dirty; fil. epib.	fil. epib.	fil. epib.

2016. Abbreviations: *, attachment site of a detached suctorian or Cothurnia -like ciliate, not counted; *?, attachment site questionable, not counted; C.:, Cothurnia buetschlii ; d,

dorsal; fil. epib., filamentous prokaryotic epibionts; Total suctorians, total amount of suctorians; v, ventral.