Sedentary ciliates from two Dutch freshwater Gammarus species by M.J. Bierhof& P.J. Roos Zoological Laboratory, University ofAmsterdam, The Netherlands Abstract the Chonotrichida. The hosts belong to the Arthropoda, class Crustacea, order Amphipoda, Gammaridae. These chosen The sedentary ciliate fauna living on the body surface of family species were Gammarus tigrinus and G. pulex from Dutch freshwater because they are both easily captured in numbers habitats has been investigated. Fourty-seven ciliate species throughout the year and they are also used in are found, of which 43 belong to the order Peritrichida, other ecological work in our faculty. As these suborder Sessilina, 3 belong to the order Suctorida and 1 animals offer a number of attach- in the great possible belongs to the order Chonotrichida. Two new species ment of took and Pseudocarchesium are described. sites, careful dissection the hosts genera Intranstylum that there is seasonal variation in the number It appears a considerable time, with the result that only a of ciliates as well as in species In epizoic composition. relatively small number of hosts could be invest- general, the species with a contractile stalk are found on igated. The list of sedentary ciliates from these external, often fast-moving, body parts. Species with a non- Gammarus is therefore of sheltered species susceptible contractile stalk seem to prefer more quiet and extended in the future. there is a succession of the being positions. After ecdysis genera Epistylis and Zoothamnium, the latter becoming dominant on older exoskeletons. MATERIAL AND METHODS INTRODUCTION The amphipod host material was collected in the provinces of North-Holland, Utrecht and Gelder- From September 1972 to December 1973 the land of The Netherlands. Two gammarid species epifauna of Gammarus tigrinus Sexton, 1939, and were found: Gammarus pulex and G. tigrinus. The At G. pulex (Linnaeus, 1758) was investigated. latter is dominant in the brackish water in the first this study was intended as a contribution to western part of the country, where this American the regional fauna, as no research with special immigrant replaced the indigenous G. pulex in the reference to these sedentary ciliates existed recent past. In each locality about 25 animals there, but secondarily the authors became in- were caught, mainly from vegetation or stones terested in relations between the of morphology the alongside bank, using a fine-mesh dip net. the ciliates and the site of attachment to the host. The ciliates were studied alive using a dif- Comparable work had been done earlier in ferential interference contrast microscope, after and other countries as West Germany, Hungary decapitation and dissection ofthe host. Denmark (e.g. Biegel, 1954; Matthes, 1950; Nen- niger, 1948; Sommer, 1951; Stiller, 1941; DESCRIPTION OF THE LOCALITIES Fenchel, 1965). Especially the Germans, from the stressed the life Erlangen school, symphoriont 1. Hierden, the "Hierdense beek", a clear and shallow habit and the host- and organ-specificity of the brook. The banks and in part also the bottom are covered with vegetation. The bottom is sandy with accumulations peritrichous ciliates. like and leaves. of coarsematerial twigs Most of the ciliates we found, likewise belong 2. Spaarnwoude. Shallow, muddy ditches in the pastures to suborder the Peritrichida, Sessilina, some between Amsterdam and Haarlem. belong to the Suctorida and 1 species belongs to 3. Burgerbrug. Reedy pool, North ofAlkmaar. Downloaded from Brill.com09/30/2021 03:53:41AM via free access 152 M. J. BIERHOF & P. J. ROOS - SEDENTARY CILIATESFROM GAMMARUS 4. Waterland. A number of ditches in the pastures, North of Epistylis gammari Precht, 1935 Amsterdam. (Fig. 3) 5. Naardermeer, lake with much vegetation and marsh-wood, Southeast of Amsterdam. Epistylis gammari; Stiller, 1971: 36 6. Several waters, South of Amsterdam, mostly broad, with banks and little (Diemen, Material: stony vegetation Bullewijk, Naardermeer, 14.VI.1973, on G. tigrinus; Bullewijk, ~ Kromme with much water lilies and Mijdrecht) or un- 19.VI.1973, onG. tigrinus. strengthenedbanks (Gein). Zooids 30x45 urn. ofthe stalk Length 70 um. RESULTS Colonies of about 5 zooids. Attachment: on the first antenna, Systematic part Epistylis sp. DESCRIPTION OF THE CILIATES, WITH REMARKS (Fig. 4) ON ATTACHMENT SITE Material: Waterland, 12.1.1973,on G. tigrinus. When the species or higher taxa are well de- The zooids scribed elsewhere, no description is given here. are of a slim vase-like shape. The discus is wrinkled. The contractile vacuole is situated somewhat above the middle ofthe zooid. Order PERITRICHIDA The vestibulum continues to the half of the ofthe zooid. The macronucleus is Suborder SESSILINA length sausage- shaped, a little bent and lying horizontally in the The recorded in this all middle of the zooid. There small food species paper are stalked, are some vacuoles. The aloricate animals, as is, with the exception of the pellicle has a coarse transverse striation. below stalkless, aloricate Lagenophrys, the rule in sym- Directly the scopula, the stalk is for about phoriont peritrichs. straight 10 urn and clearly striped. Further the stalk is down, enveloped in a slimy, Family EPISTYLIDAE wrinkled sheath. Zooids 30x60 um. of the Length colony 250 urn. Epistylis zschokkei (Keiser, 1921) Three colonies of 9, 6 and 2 zooids. (Fig. 1) Attachment: on the first antenna, between the setae. Epistylis zschokkei; Kahl, 1935: 729. Material: Waterland, 30.XI.1972, on G. tigrinus; Diemen, 28.V.1972, on G. tigrinus. Epistylis nitocrae Precht, 1935 (Fig. 5) Zooids 30x45 um. Colonies of 4—6 zooids. Epistylis nitocrae Precht, 1935: 438. the Attachment: on joints of the gnathopods. Material: Naardermeer, 19.1.1973, onG. tigrinus. Zooids 35 65 Epistylis thienemanniSommer, 1951 x pm. Two colonies of 25 and 60 zooids. (Fig. 2) Attachment: on the third pereiopod. Epistylis thienemanniSommer, 1951: 372. Material: Burgerbrug, 24.X. 1972, onG. tigrinus. Epistylis ovalis Biegel, 1954 Zooids 60 x 100 um. (Fig. 6) of Length the stalk 45 um. Greatest breadth of the stalk 40 ovalis um. Epistylis Biegel, 1954: 161 Colonies of (1) - 5 zooids. Material: Diemen, 28.V. 1973, on G. tigrinus; Gein, Attachment: on all gills. 23.VII.1973, on G. tigrinus. Downloaded from Brill.com09/30/2021 03:53:41AM via free access 153 BIJDRAGEN TOT DE DIERKUNDE, 46 (2) - 1977 Fig. 1. Epistylis zschokkei (Keiser, 1921). Fig. 2. Epistylis thienemanni Sommer, 1951. Fig. 3. Epistylis gammariPrecht, 1935. Fig. 4. Epistylis sp. Downloaded from Brill.com09/30/2021 03:53:41AM via free access 154 M. J. BIERHOF & P. J. ROOS - SEDENTARY CILIATESFROM GAMMARUS Fig. 5. Epistylis nitocrae Precht, 1935. Fig. 6. Epistylis ovalis Biegel, 1954. Fig. 7. Epistylis cf. ovalis Biegel, 1954. Fig. 8. Epistylis cf. ovum (Kent, 1881). Downloaded from Brill.com09/30/2021 03:53:41AM via free access 155 BUDRAGEN TOT DE DIERKUNDE, 46 (2) - 1977 Zooids 30 x 50 um. The zooid is broad, nearly rectangular. The Colonies of three zooids. two or peristome is rather thick, not clearly separated. Attachment: on the gnathopods The discus is slightly wrinkled. The contractile vacuole is situated near the rim of the peristome. The rather narrow vestibulum continues into the Epistylis cf. ovalis Biegel, 1954 lower half of the zooid. The ribbon-like macro- (Fig. 7) nucleus is slightly bent, situated in the underpart Epistylis ovatis Biegel, 1954: 161. of the zooid. There are few food vacuoles. The has striation. pellicle a very fine transverse Material: Gein, 14.VI.1973, on G. pulex. Zooids 15 x 25 um. The zooid resembles much that of the very Stalk 10x40 um. above-mentioned E. ovalis. However, the macro- Three animals. nucleus is situated in the part of the zooid upper Attachment: between the spines at the tip of the and the stalk is striped lengthwise. telson. Zooids 25 x45 |im. Stalk 10 x 15 um. Attachment: on the third pereiopod. Family VORTICELLIDAE Epistylis cf. ovum (Kent, 1881) (Fig. 8) Carchesium gammari Precht, 1935 Epistylis ovum; Stiller, 1941: 354. (Fig. 11) Material: Naardermeer, 19.1.1973, onG. tigrinus. Carchesium gammari Precht, 1935: 442. The zooid is vase-like. The discus is convex. The Material: Hierden, 26.IV. 1973, on G. pulex. peristome contracts snout-like. The contractile 40 70 vacuole lies somewhat above the middle of the Zooids x um. Five colonies of 2, 3,4 and 5 zooids. zooid. The narrow vestibulum continues to about Attachment: on the rims of the gills. half the length of the zooid. The nucleus is slightly bent, lying horizontally in the centre. There are some scattered food vacuoles. The Carchesium duplicatum Precht, 1935 stalk is thick, wrinkled, with a vague lengthwise (Fig. 12) striation. Zooids 20x40 um. Carchesium duplicatum Precht, 1935: 441 One colony of 8 zooids. Attachment: between the spines of the tip of the Material: Hierden, 22.11.1973, I5.V.1973 and 6.VI1I.1973, on G. third uropod. pulex. Zooids 30 50 x urn. of the 150 Epistylis salina Stiller, 1941 Length colony urn. (Fig. 9) Colonies up to about 50 zooids. Attachment: on the rims of the gills of the Epistylis salina Stiller, 1941: 385. pereiopods. Material: Hierden,6.VIII. 1973, on G. pulex. Zooids 25 x 55 um. 10 50 Carchesium jaerae Precht, 1935 Stalk x um. (Fig. 13) Many small colonies of 2 —9 zooids. Attachment: on first and second antennae, coxal Carchesium jaerae Precht, 1935: 442. plates and gills. Material: Gein, 23.VII.1973, on G. tigrinus. Rhabdostyla sp. Zooids 35 55 x um. (Fig. 10) Nine colonies of 2, 3 and 5 zooids. Attachment: the rims of the Material: Gein, 23.VI1.1973, on G. tigrinus. on gills. Downloaded from Brill.com09/30/2021 03:53:41AM via free access 156 M. J. BIERHOF & P. J. ROOS - SEDENTARY CILIATES FROM GAMMARUS Fig. 9. Epistylis salina Stiller, 1941. 10.