Diversity of freshwater ciliates (Protista) from Argentina Gabriela C. Küppers1,* & María C. Claps2 1Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, CONICET-UNLP, Argentina. 2Instituto de Limnología “Dr. R. A. Ringuelet”, CONICET-UNLP, Argentina *Coreesponding author: gkuppers@fcnym.unlp.edu.ar Abstract. Diversity of ciliates from freshwater and soil were scarcely investigated in Argentina, in spite of their ecological role in these ecosystems and the huge environmental heterogeneity that can be found in this country. In the present study, we describe the morphology of nine species from a temporary pond in Buenos Aires province, by means of live observations and protargol impregnations. Stentor igneus Ehrenberg, Pseudochilodonopsis piscatoris (Blochmann), Vorticella halophila Stiller, Intranstylum invaginatum Stokes, and Epistylis rotans Švec were recorded for the first time in Argentina, and in most cases, are new for the Neotropical realm as well. In addition, an updated checklist on freshwater ciliates from Argentina is provided, based on ciliates listed for the Salado River basin in the Buenos Aires province, new findings from Rancho Hambre peat bog pools in Tierra del Fuego province and a pond from Misiones province. Keywords. Argentina, Ciliophora, diversity, new records. Introduction According to the literature and based on own investigations, a total of 208 freshwater ciliate species were recorded in Argentina (Küppers & Claps, 2012). Unfortunately; diversity of this group of protists is highly underestimated, in spite of the ecological role of ciliates in microbial food webs and the huge environmental heterogeneity that can be found in Argentina. In marine ecosystems; several investigations on diversity, biogeography, phylogeny, and ecology of plankton ciliates, mostly on tintinnids, were conducted by Balech (Akselman Cardella, 2008, list of publications), Boltovskoy & Alder (1989, 1992), Boltovskoy et al. (1990), Alder & Boltovskoy (1991); and more recently, by Thompson et al. (1999, 2001, 2005), Santoferrara & Alder (2009a, b; 2012), and Santoferrara et al. (2011, 2012, 2013, 2014, 2015). Brackish water ciliates were mostly investigated by Souto (1974), Pettigrosso et al. (1997), Pettigrosso (2003), Pettigrosso & Popovich (2009), Barría de Cao (1992), and Barría de Cao et al. (1997, 2013). On the contrary, only few researchers focused on ciliates from freshwater and soil (Küppers & Claps, 2012 and citations therein). The aim of the present study is to characterize biometrically and describe the morphology of nine ciliates from a temporary pond located in Buenos Aires province, by means of live observations and protargol impregnations. These ISNN 1517-6770 Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 42 species were recorded over a 3-year survey along with other species that were described elsewhere and listed in Küppers & Claps (2012). In addition, this checklist on freshwater ciliates from Argentina is updated with species listed for the Salado River basin in the Buenos Aires province, new findings from Rancho Hambre peat bog pools in Tierra del Fuego province, and a new record from Misiones province. Material and Methods A temporary pond located near the city of Poblet, Buenos Aires province (35°05’S, 57°48’W), was surveyed during 2003-2005, where plankton and periphyton samples were obtained monthly. This pond went through drought phases mainly in summer and was colonized by hydrophytes like Ludwigia peploides (Kunth) Raven and Alternanthera phyloxeroides (Martius) Grisebach during desiccation. These macrophytes persisted over the filling phase in autumn, when periphytic samples were obtained. The rest of the hydroperiod was characterized by open waters. For detail description and location of this temporary pond see Küppers et al. (2006). During the publication process of the checklist by Küppers & Claps (2012), other freshwater ciliates were described or published that are listed in the present work as well (see Küppers & Claps, 2010; Küppers et al. 2011). The Salado River is a lowland river located in the Pampean plain from Buenos Aires province, where land floodings over weeks or months occur seasonally; thus influencing the river regime and consequently, its electrical conductivity and transport of dissolved and particulate material (Claps et al., 2009). Besides, sedimentary aquifers with high sodium-chloride concentrations in the headwater of the river influence the water chemistry of streams and lakes that also contribute to the water balance of the Salado River (Claps et al., 2009). From the headwater sector through the mouth of the river, the plankton of several tributaries, artificial channels, and backwater ponds were sampled since 1997 by Solari et al. (2002), Gabellone et al. (2005), and Claps et al. (2009), where several species of freshwater as well as brackish and marine ciliates were found. For detail information on the geographic location of sampling sites and water characteristics see Gabellone et al. (2008) and previously cited papers. Rancho Hambre is a dome-shaped, ombrotrophic peat bog located along the southernmost ridges of the Andes in Tierra del Fuego province. Its landscape is dominated by a matrix of Sphagnum magellanicum Bridel mosses that holds pools of different size and with nutrient poor, colored, acid waters (Roig & Roig, 2004). Plankton samples were taken in five of these pools during a limnological survey in 2008-2010. For detail description of sampling sites, morphometric and physico-chemical characteristics of these pools see González Garraza et al. (2012). A new ciliate was cited in Misiones province, northeast from Argentina, from a pond formed in the floodplain of the Garupá stream (Peso et al., 2015), which is also included in the list. Most ciliates described below were found in fresh samples from the pond located near Poblet (Buenos Aires province) and persisted in Petri dishes over 1-2 weeks. Ciliates from Rancho Hambre pools were kept in a culture chamber at 4 °C and 12 hs. light period. Observations were made at magnifications of 10× and 40× under the stereo microscope and at 100×, 400×, and 1000× under the bright field microscope. After observing Küppers & Claps Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 43 ciliates in vivo, cells were fixed in Bouin’s solution and impregnated with protargol according to Wilbert (1975). Drawings of living cells are free- hand sketches, while impregnated ciliates were illustrated with the aid of a camera lucida. Peritrichs were only studied in vivo, because impregnations were too strong. Classification and terminology follow Lynn (2008). Identification of species in the genus Stentor Oken were performed according to Foissner & Wölfl (1994), Vorticella Linnaeus following Warren (1986), and specific taxonomic papers cited below. Results and Discussion Additions to the checklist of freshwater ciliates from Argentina is provided in Table 1. With these findings, the number of freshwater ciliates increases up to 229 species. In the Salado River basin a total of 34 identified species were recorded, from which 5 of the species reported here are new records for Argentina. Some of these ciliates are known to inhabit brackish and / or marine environments. The fluctuating water regime of the river and the chemical nature of the basin cause wide variations in electrical conductivity over wet and dry seasons; thus, probably conditioning ciliate assemblages and allowing the occurrence of euryhaline and halophile species. Until the investigations of Küppers et al. (2011), Quiroga et al. (2013) and unpublished data (Küppers et al., unpubl.), only the peritrich Epistylis cf. umbilicata was known from lakes in Tierra del Fuego (Küppers & Claps, 2012). In the present contribution, a total of 28 identified species are listed in this province, with 13 ciliates being also new records for Argentina. In Misiones province, Peso et al. (2015) found the peritrich Ophrydium versatile (O. F. Müller, 1786) Ehrenberg, 1830 for the first time in a pond formed from the Garupá stream floodplain. This is the only ciliate identified up to species level that was cited for this province. The following nine species from a temporary pond near the city of Poblet in Buenos Aires province were mentioned in Küppers & Claps (2012) but were not biometrically characterized at that time. Five species were new for the freshwater ciliate fauna from Argentina and three of these, were also new for the Neotropical realm. Phylum Ciliophora Doflein Class Heterotrichea Stein Order Heterotrichida Stein Family Stentoridae Carus Stentor igneus Ehrenberg, 1838 (Figure 1; Table 2) Body size in vivo 392-490 µm long, trumpet- shaped, with a short mucous lorica. Cortical granules pink-colored, arranged in longitudinal stripes between somatic kineties. Endosymbiotic algae absent. Contractile vacuole anteriorly on the left, with posterior collecting canal (Figure 1a). Nuclear apparatus formed by a single, spherical bead and 3 globular micronuclei. Oral ciliature with 142 membranelles and paroral membrane parallel to the adoral zone. Somatic ciliature composed of 32-36 longitudinal kineties and 7-8 kineties in peristomial region (Figure 1b). Occurrence and autoecology. This species was recorded in autumn 2004, on Alternanthera philoxeroides and Ludwigia peploides, under the following physico-chemical conditions: conductivity 226.7 µS cm-1, dissolved oxygen concentration 6.3 mg L-1, temperature 8.6°C, pH 5.4. Remarks. Stentor igneus is probably a cosmopolitan Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 44 Sp ec ie s BA 1 BA 2 S1 S2 S3 S4 S4 a S4 b S4 c S5 S6 S7 S8 S9 S1 0 S1 1 S1 2 TF M Re fe re nc es Ap oa m ph isi el la hy m en op ho ra (S to ke s, 1 88 6) Be rg er , 1 99 9 + + Kü pp er s & Cl ap s ( 20 13 ) As co bi us le nt us He nn eg uy , 1 88 4 + N ew re co rd in SR B As pi di sc a ci ca da (O . F . M ül le r, 17 86 ) C la pa rè de & La ch m an n, 1 85 8 + + + + + + + + N ew re co rd in SR B As pi di sc a ly nc eu s (O . F . M ül le r, 17 73 ) Eh re nb er g, 1 83 0 + + + N ew re co rd in SR B, T F Ba la ni on pl an ct on ic um (F oi ss ne r, O le ks iv & M ül le r, 19 90 ) Fo iss ne r, Be rg er & Ko hm an n, 1 99 4 + Q ui ro ga e t a l. (2 01 3) Br yo m et op us sp ha gn i ( Pe na rd , 19 22 ) K ah l, 19 32 + N ew re co rd in Ar ge nti na Ta bl e 1. A dd iti on s t o th e ch ec kl ist o n fr es hw at er c ili at es fr om A rg en tin a, re co rd ed in B ue no s A ire s p ro vi nc e (B A1 , B A2 , S al ad o Ri ve r b as in , S RB : S 1- S1 2) , M isi on es pr ov in ce (M ), an d Ti er ra d el F ue go p ro vi nc e (T F) . B A1 , t em po ra ry p on d ne ar P ob le t; BA 2, te m po ra ry p on d ne ar D ol or es ; S 1, S al ad o st re am ; S 2, P iñ ei ro st re am ; S3 , J un ín ; S 4, S al ad ill o st re am ; S 4a , M er ca nt e Ca na l; S4 b, V in cu la ci ón C an al ; S 4c , d el E st e Ca na l; S5 , A ch up al la s; S 6, R ut a 30 ; S 7, S al ad ill o Va lli m an ca st re am ; S 8, Ro qu e Pé re z; S 9, G or ch s; S 10 , B el gr an o; S 11 , D es tin o; S 12 , G ue rr er o; M , p on d of th e Ga ru pá st re am fl oo dp la in ; T F, po ol s f ro m R an ch o Ha m br e pe at b og . Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 45 Table 1. Additions to the checklist on freshw ater ciliates from Argentina. Bursaridium pseudobursaria (Fauré-Frem iet, 1924) Kahl, 1927 + N ew record in Argentina Carchesium polypinum (Linnaeus, 1758) Ehrenberg, 1930 + + N ew record in SRB Cinetochilum m argaritaceum (Ehrenberg, 1831) Perty, 1849 + N ew record in TF Clapsiella m agnifica Küppers, 2014 + Küppers (2014) Colpoda steini M aupas, 1883 + N ew record in TF Condylostom a cf. spatiosum + N ew record in Argentina Deviata polycirrata Küppers & Claps, 2010 + + Küppers & Claps (2010) Diophrys cf. appendiculata + N ew record in Argentina Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 46 Ta bl e 1. A dd iti on s t o th e ch ec kl ist o n fr es hw at er c ili at es fr om A rg en tin a. Ep isp at hi di um am ph or ifo rm e (G re eff , 1 88 8) Fo iss ne r, 19 84 + N ew re co rd in T F Fa br ea sa lin a He nn eg uy , 1 89 0 + + + + + + + + + + + + + + + N ew re co rd in Ar ge nti na Fr on to ni a c f. ac um in at a + N ew re co rd in Ar ge nti na Fr on to ni a at ra (E hr en be rg , 1 83 3) Bü ts ch li, 1 88 9 + N ew re co rd in T F Ha lte ria gr an di ne lla (O . F. M ül le r, 17 73 ) Du ja rd in , 1 84 1 + + + + + + + + + + + Q ui ro ga e t a l. (2 01 3) Le m ba di on lu ce ns (M as ke ll, 1 88 7) Ka hl , 1 93 1 + N ew re co rd in Ar ge nti na Li m no st ro m bi di um vi rid e (S te in , 1 86 7) Kr ai ne r, 19 95 + N ew re co rd in SR B Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 47 Table 1. Additions to the checklist on freshw ater ciliates from Argentina. Linostom ella vorticella (Ehrenberg, 1833) Aescht in Foissner, Berger & Schaum burg, 1999 + N ew record in SRB M esodinium acarus Stein, 1867 + N ew record in Argentina O phrydium versatile (O . F. M üller, 1786) Ehrenberg, 1830 + + N ew record in TF, M Param ecium aurelia com plex + N ew record in TF Param ecium bursaria (Ehrenberg, 1831) Focke, 1836 + N ew record in TF Parasterkiella thom psoni (Foissner, 1996) Küppers, da Silva Paiva, do N ascim ento Borges, Harada, González Garraza & M ataloni, 2011 + Küppers et al. (2011) Pelagostrom bidium fallax (Zacharias, 1896) Krainer, 1991 + Q uiroga et al. (2013) Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 48 Ta bl e 1. A dd iti on s t o th e ch ec kl ist o n fr es hw at er c ili at es fr om A rg en tin a. Pl ag io py la n as ut a St ei n, 1 86 0 + N ew re co rd in T F Po do ph ry a fa lla x Di ng fe ld er , 1 96 1 + N ew re co rd in T F Ri m os tr om bi di um hy al in um (M ira bd ul la ev , 19 85 ) P et z & Fo iss ne r, 19 92 + Q ui ro ga e t a l. (2 01 3) St en to r c oe ru le us (P al la s, 1 76 6) Eh re nb er g, 1 83 1, + N ew re co rd in T F St en to r c f. ar au ca nu s + TF Sti ch ot ric ha ac ul ea ta W rz es ni ow sk i, 18 66 + N ew re co rd in Ar ge nti na St ro bi lid iu m ca ud at um (F ro m en te l, 18 76 ) Fo iss ne r, 19 87 + + + + + N ew re co rd in SR B, T F St ro m bi di um su lc at um C la pa rè de & L ac hm an n, 1 85 9 + + + N ew re co rd in Ar ge nti na St ro m bi di um c f. st yl ife r + + + + N ew re co rd in Ar ge nti na Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 49 Tetrahym ena pyriform is com plex + N ew record in TF Thylakidium pituitosum Foissner, 1980 + N ew record in Argentina Tokophrya cf. infusionum + N ew record in Argentina U roleptus w illii Sonntag, Strüder- Kypke & Sum m erer, 2008 + N ew record in Argentina Vorticella m icrostom a Ehrenberg, 1830 + + + + + + + + + + N ew record in SRB Table 1. Additions to the checklist on freshw ater ciliates from Argentina. Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 50 species; although, it was not yet found in Australia and Antarctica (Foissner et al., 1992). In the Neotropical realm, it was previously recorded in México (Aladro Lubel et al., 2006, 2009), Perú (Foissner et al., 1992), and Brazil (Regali- Seleghim et al., 2011), while represents a new finding for Argentina. Morphometric features coincide with those provided by Foissner et al. (1992). The populations studied by Song & Wilbert (1989) from Bonn, Germany, had a lower number of adoral membranelles (76-96 vs. 142, respectively) and somatic kineties (23-29 vs. 32- 36, respectively). According to Foissner & Wölfl (1994), most important features to identify species within the genus Stentor are the presence/absence of endosymbionts, morphology of the nuclear apparatus, and color of cortical granules. In this context, the species recorded in this study coincides with S. igneus. Stentor roeselii Ehrenberg, 1835 (Figure 2; Table 2) Body size in vivo 462-1344 µm in length; trumpet- shaped. With posterior mucous lorica. Cortical granules colorless, arranged in longitudinal stripes between somatic kineties. Endosymbiotic algae absent. Contractile vacuole on left of buccal funnel, with posterior collecting canal (Figure 2a). Nuclear apparatus formed by vermiform macronucleus and 4-8 globular micronuclei. Oral ciliature composed of 142-177 membranelles and paroral membrane parallel to adoral zone. Somatic ciliature composed of 42-63 longitudinal and 9-12 peristomial kineties (Figure 2b). Occurrence and autoecology. This species was found in plankton samples obtained in spring 2003 and 2004, under the following ranges of physico- chemical parameters: conductivity 156.3-226.7 µS cm-1, dissolved oxygen concentration 4.5-7.1 mg L-1, temperature 8.6-19.2°C, pH 5.4-9.5. Food vacuoles contained green algae. Occasionally, this species was observed to live in great numbers, in mucous masses formed by individual loricae. Remarks. Stentor roeselii is probably cosmopolitan; although, it was not yet found in Australia and Antarctica (Foissner et al., 1992). This species was previously recorded in México (Aladro Lubel et al., 2006, 2009) and Brazil (Pauleto et al., 2009; Regali-Seleghim et al., 2011; Velho et al., 2013). In Argentina, Modenutti (1991) found S. roeselii in lotic environments of del Plata sub-catchment and Zaleski & Claps (1999) in San Miguel del Monte lake (Buenos Aires province), epiphytic on Myriophyllum quitense Kunth. Morphometric features provided by different authors are somewhat variable and in some cases are different from those observed in the present study; although, important features to identify species within the genus according to Foissner & Wölfl (1994) are coincident. In Figure 1. Morphology of Stentor igneus in vivo (a) and after protargol impregnation (b). Arrowhead indicates micronuclei. AM, adoral membranelles; CG, cortical granules; CV, contrac- tile vacuole. Scale bar = 50 µm. Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 51 the revision of the species, Foissner et al. (1992) mentioned a higher number of micronuclei than those observed in the present study (7-20 vs. 4-8, respectively), somatic kineties (about 80 vs. about 50 on average, respectively), and peristomial kineties (14-42 vs. 9-12, respectively). The Argentinean population, however, is similar to that described by Song & Wilbert (1989) from a stream in Bonn, Germany. Class Phyllopharingea de Puytorac et al. Subclass Phyllopharyngia de Puytorac et al. Order Chlamydodontida Deroux Family Chilodonellidae Deroux Pseudochilodonopsis piscatoris (Blochmann, 1895) Foissner, 1979 (Figure 3; Table 3) Body size 81-105 × 26-42 µm after protargol impregnation; dorsoventrally flattened, with a Figure 2. Morphology of Stentor roeselii in vivo (a) and after protargol impregnation (b). CV, contractile vacuole; Ma, ma- cronucleus; Mi, micronucleus. Scale bar = 50 µm. Character Mean M Min. Max. SD n Body length in vivo 441.0 919.3 441.0 1015.0 392.0 462.0 490.0 1344.0 69.3 323.4 2 18 Peristome diameter in vivo --- 120.5 --- 112.0 --- 98.0 --- 154.0 --- 15.3 --- 18 Lorica length in vivo --- 774.2 --- 770.0 --- 630.0 --- 1008.0 --- 110.0 --- 18 Macronuclear nodules number 1 1 1 1 1 1 1 1 0 0 3 18 Macronucleus length 32.7 --- 30.8 --- 28.0 --- 39.2 --- 5.8 --- 3 --- Macronucleus width 27.8 --- 25.9 --- 22.4 --- 35.0 --- 6.5 --- 3 --- Micronuclei number 3 5.6 3 5 3 4 3 8 0 1.5 1 5 Micronuclei width 1.8 3.5 1.7 3.8 1.7 2.4 2.1 5.0 0.2 0.9 3 7 Membranelles number 142.0 164.5 142.0 165.5 142.0 142 142.0 177 0 13.1 1 6 Table 2. Morphometric data on Stentor igneus (first line) and S. roeselii (second line). M, median; Max., maximum observation; Min, minimum observation; n, number of observations; SD, standard deviation. Measurements are in µm and correspond to protargol impregnated specimens, unless indicated. Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 52 Somatic kineties number 34 48.7 34 47.0 32 42 36 63 2.8 7.4 2 7 Peristomial kineties number 7.5 10.9 7.5 11.0 7 9 8 12 0.7 1.2 2 7 Table 2. Continuation. preoral beak in anterior left margin and posterior end pointed, sometimes rounded. Cytoplasm colorless. Two contractile vacuoles; one located in midbody on right cell margin, and other one in posterior third on left body margin (Figure 3a). With conspicuous dorsal cytoplasmic protrusion or spine posteriorly. Macronucleus ellipsoidal; micronucleus not observed. Cyrtos formed by about 14 rods. Ventral ciliature composed of 5-6 left and 5-6 right kineties, separated by a bare postoral field. One fragmented preoral kinety and 2 circumoral kineties. Preoral kinety consists of 4 fragments; fourth fragment extends around cytopharynx opening (Figure 3b). Dorsal brush arched anteriorly (Figure 3c). Occurrence and autoecology. This species was found in winter-spring 2004 and autumn-spring 2005, in plankton as well as periphyton samples, under the following ranges of physico-chemical parameters: conductivity 133-243 µS cm-1, dissolved oxygen concentration 4.5-8.0 mg L-1, temperature 4.0-19.2 °C, pH 5-9.5. Remarks. Pseudochilodonopsis piscatoris was previously found in Europe (Foissner et al., 1991). For Argentina and the Neotropical realm, it represents a new record. Morphometric features coincide with those observed by Foissner (1979) and those provided by Foissner et al. (1991); although the dorsal spine from Argentinean population is distinctly more conspicuous. Class Oligohymenophorea de Puytorac et al. Subclass Peritrichia Stein Order Sessilida Kahl Family Vorticellidae Ehrenberg Vorticella convallaria Linnaeus, 1758 (Figure 4a; Table 4) Zooid in vivo 63-98 × 49-70 µm, inverted bell-shaped. Peristomial disc not elevated above peristome; maximum body width less than peristomial lip diameter. Pellicle finely striated and with normal ribbing between striations. Contractile vacuole below peristome. Contractile stalk with evident thecoplasmic granules on myoneme. Macronucleus J-shaped. Occurrence and autoecology. This species was found in spring 2003 and autumn-winter 2004 on Alternanthera philoxeroides and Ludwigia peploides, under the following ranges of physico- Figure 3. Morphology of Pseudochilodonopsis piscatoris in vivo (a) and after protargol impregnation (b, c). a, b. Ventral view; c. Dorsal view. C, cyrtos; CV, contractile vacuole; DB, dorsal brush; LK, left ventral kineties; Ma, macronucleus; PO, fragmented preoral kinety; RK, Right ventral kineties. Scale bar = 30 µm. Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 53 Character Mean M Min. Max. SD n Body length 94.5 94.0 81.0 105.0 8.2 8 Body width 37.6 39.5 26.0 42.0 5.6 8 Macronucleus length 25.4 27.0 20.0 28.0 2.8 7 Macronucleus width 13.0 13.0 11.0 15.0 1.5 7 Dorsal spine length 14.1 14.0 10.5 17.0 2.6 5 Dorsal spine width 2.8 2.8 2.8 2.8 0 1 Circumoral kineties number 2 2 2 2 0 7 Kineties in left ventral field number 5.2 5.0 5 6 0.4 6 Kineties in right ventral Field number 5.2 5.0 5 6 0.4 5 Table 3. Morphometric data on Pseudochilodonopsis piscatoris. Abbreviations are indicated in Table 2. Measurements correspond to protargol impregnated specimens. chemical parameters: conductivity 145-227 µS cm-1, dissolved oxygen concentration 5.5-8.8 mg L-1, temperature 2.4-24.1 °C, pH 5.0-8.4. Remarks. Vorticella convallaria belongs to a cosmopolitan species complex that occur in Europe, Asia, Antarctica, and America (Foissner et al., 1992). In South America, it was mentioned by Guillén et al. (2003) in swamps from Villa in Perú, in freshwater environments from México (Aladro Lubel et al., 2009) and Brazil (Regali-Seleghim et al., 2011; Velho et al., 2013). In Argentina, this species was previously recorded in Buenos Aires province by Cela (1972) in ponds from Berisso, by Claps (1984) on Scirpus californicus (Meyer) Steud. from Atalaya (Río de la Plata estuary), by Claps & Modenutti (1984) on S. californicus from San Miguel del Monte Lake, on Stuckenia striata (Ruiz & Pav.) Holub from Chascomús Lake, and on Pistia stratiotes L. from Punta Lara (Río de la Plata estuary); finally, Modenutti (1987) found V. convallaria in plankton samples of Rodríguez stream from La Plata city. Morphometric features coincide with those mentioned by Warren (1986) and Foissner et al. (1992). Vorticella pulchella Sommer, 1951 (Figure 4b; Table 4) Zooid size in vivo 30.0-43.3 µm × 26.6-33.3 µm. Peristomial disc prominently elevated above peristome and maximum body width approximately equal to peristomial lip diameter; body constricted below peristomial lip. Pellicle conspicuously striated and with convex ribbing between striation. Contractile vacuole in the center of body. Contractile stalk with inconspicuous thecoplasmic granules on myoneme, but evident upon contraction. Macronucleus C-shaped, located horizontally below peristome. Occurrence and autoecology. Vorticella pulchella was found in winter 2004, on L. peploides, under the following ranges of physico-chemical parameters: Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 54 conductivity 163.3-227.0 µS cm-1, dissolved oxygen concentration 5.5-8.8 mg L-1, temperature 2.4-7.6 °C, pH 5-6. Remarks. Vorticella pulchella is distributed in Switzerland (Sommer, 1951) and Hungary (Stiller, 1971). In Argentina, it was previously recorded by Zaleski & Claps (2001) on Myriophyllum quitense and suspended detritus from San Miguel del Monte Lake, Buenos Aires province. Stiller (1971) found V. pulchella as epibiont on copepod crustaceans. Morphometric features are coincident with those mentioned by Warren (1986) and those observed by Zaleski & Claps (2001). Vorticella striata Dujardin, 1841 (Figure 5a,b; Table 4) Zooid size in vivo 56-84 µm × 35-49 µm. Peristomial disc not elevated above peristome and maximum body width less than peristomial lip diameter. Pellicle conspicuously striated and with convex ribbing between striations. Contractile vacuole just below peristome. Contractile stalk with evident thecoplasmic granules on myoneme. Macronucleus C-shaped, located horizontally below peristome. Occurrence. This species was recorded in summer 2005, in rewetted soil samples obtained from the pond bed during a drought period. Remarks. Vorticella striata belongs to the Vorticella aquadulcis complex, which species were recorded in Eurasia and America (Foissner et al., 1992). In 2008, Kovalchuk redescribed V. striata based on a population from Ukraine. In Argentina, this species was previously found by Claps & Modenutti (1984) on Azolla filiculiodes Lam. in Las Víboras stream from Magdalena and on A. filiculoides, Ricciocarpus natans L., Lemna sp., and Wolfiella sp. in Chascomús Lake, Buenos Aires province. The occurrence of this peritrich on different type of aquatic macrophytes indicates its low specificity for the substrate. Moreover, this species was also observed as epibiont on subitaneous eggs of the social rotifer Sinantherina semibullata (Thorpe) in temporary ponds from Punta Lara and Magdalena, Buenos Aires province (Küppers, unpub.). In agreement with our observations, Warren (1986) mentioned that this species could occasionally be found as epibiont. Fernández-Leborans & Tato- Porto (2000) mentioned V. striata on cladocerans and copepods and it was also found on a crayfish crustacean from México (Mayén Estrada & Aladro Lubel, 2002). In the present study, the finding of this species in rewetted soil samples indicate that it developed from resting cysts, which were also observed (Figure 5b). Morphometric features are in agreement with those mentioned by Warren (1986) and those observed by Claps & Modenutti (1984). Figure 4. Morphology of Vorticella convallaria (a) and V. pul- chella (b) in vivo. Arrowhead in (b) indicate conspicuously striated pellicle and convex ribbing between striations. CV, contractile vacuole; Ma, macronucleus. Scale bars = 20 µm. Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 55 Vorticella halophila Stiller, 1941 (Figure 5c; Table 4) Zooid in vivo 63-102.5 µm × 35-56 µm. Peristomial disc not elevated above peristome and maximum body width less than peristomial lip diameter. Body constricted below peristome. Pellicle conspicuously striated and with convex ribbing between striations. Two contractile vacuoles, located below peristome. Contractile stalk with scarce colorless thecoplasmic granules on myoneme. Macronucleus J-shaped. Occurrence and autoecology. This species was found in summer 2005, in rewetted soil samples obtained from the dried pond bed. It was also observed in spring 2005 in plankton samples, under the following physico-chemical conditions: conductivity 206.7 µS cm-1, dissolved oxygen concentration 4.5 mg L-1, temperature 11.6 °C, pH 8.7. Remarks. Vorticella halophila was recorded in Hungary (Stiller, 1971). In Argentina and the rest of South America, it represents a new finding. The development of this species from rewetted soil samples from the dried bed of the pond, indicate that it is able to form resting cysts. Moreover, this is the first time V. halophila is recorded in soil samples. Unfortunately, resting cysts were not observed. Morphometric characteristics coincide; in general, with those mentioned by Warren (1986); although, specimens from the present study had greater size (40-50 µm vs. 63-102 µm, respectively). Intranstylum invaginatum Stokes, 1886 (Figure 6; Table 4) Zooid size in vivo 70-98 µm × 21-28 µm; inverted elongated bell-shaped. With peristomial lip. Peristomial disc slightly convex, with a central button-like protuberance, and slightly elevated above peristome (Figure 6a). Maximum body width less than peristomial lip diameter. Upon contraction, with an anterior snout-like protuberance and slightly folded posteriorly (Figure 6b). Pellicle smooth, without evident striation. Contractile vacuole on the peristome. Macronucleus C-shaped, horizontally located in anterior third of body. Stalk very short, with inconspicuous myoneme and posterior adhesive disc. Occurrence and autoecology. This species was found in winter 2004, epibiont on ostracods in the genus Cypris O. F. Müller (Fig. 6c), under the following water conditions: conductivity 227 µS cm-1, dissolved oxygen concentration 5.5 mg L-1, temperature 2.4°C, pH 5. Remarks. Intranstylum invaginatum was recorded in North America and Germany on the ostracods Figure 5. Morphology of Vorticella striata (a, b) and V. halo- phila (c) in vivo. a, c. Zooids. b. Cyst with pulsating contractile vacuole. Arrowheads indicate pellicle conspicuously striated (a) and thecoplasmic granules (c). CV, contractile vacuole; Ma, macronucleus. Scale bars = 20 µm. Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 56 Cypris and Candona Baird and also on cladocerans in Germany, England, Finland, and Italy (Kahl, 1935; Pätsch, 1974; Fernández-Leborans & Tato-Porto, 2000; Chatterjee et al., 2013). In Argentina and the rest of South America, it represents a new finding. Morphology is coincident with specimens recorded on Cypris by other authors; although, stalk is much shorter in the Argentinean population. On the contrary, epibionts on Candona have greater stalk length and those specimens found on cladocerans lack the button-like protuberance on center of peristomial disc (Kahl, 1935). To our knowledge, this species has rarely been described morphologically after its original description by Stokes (1886) and the observations of Kahl (1935). Unfortunately, protargol impregnations were very strong in order to observe its infraciliature. Family Epistylididae Kahl Epistylis rotans Švec, 1897 (Figure 7; Table 4) Colony size in vivo about 4 mm high; arbustive, with principal stalk noncontractile and dichotomously branched. Zooid in vivo 196-252 µm × 77-98 µm; inverted bell-shaped, with anterior end of body curved or inclined. With peristomial lip; peristomial disc slightly convex, not elevated above peristome. Maximum body width less than peristomial lip diameter. Pellicle conspicuously striated, with convex ribbing between striations, and with small warts that become evident in peristomial zone. Upon contraction, zooid globular-shaped and peristomial lip covers the peristome completely. Contractile vacuole on the peristome. Macronucleus Figure 6. Morphology of Intranstylum invaginatum in vivo. a. Zooid with button-like protuberance in center of peristomial disc (arrowhead). b. Zooid upon contraction. c. Basibiont ostracod (Cypris sp.), showing zooids in posterior region of the valves. CV, contractile vacuole; Ma, macronucleus. Scale bar = 20 µm. Figure 7. Morphology of Epistylis rotans in vivo. a. Zooid. b. Zooid upon contraction. c. General view of the colony. CV, contractile vacuole. Scale bar = 20 µm Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 Küppers & Claps 57 C-shaped, horizontally located with respect to cell major axis. Stalk smooth and iridescent at low magnification (less than 40×), colonized by epibiont choanoflagellates. Occurrence and autoecology. This species was found in autumn 2004; on A. philoxeroides, L. peploides, and suspended organic matter, under the following water characteristics: conductivity Character Spp. Mean M Min. Max. n Zooid length Vc Vp Vs Vh Ii Er 80.5 38.3 63.0 82.3 89.3 231.5 80.5 40.0 59.5 84.0 91.0 238.0 63.0 30.0 56.0 63.0 70.0 196.0 98.0 43.3 84.0 102.5 98.0 252.0 20 7 8 15 11 15 Zooid width Vc Vp Vs Vh Ii Er 56.7 28.2 39.4 47.2 26.1 85.9 56.0 28.0 38.5 49.0 28.0 84.0 49.0 26.6 35.0 35.0 21.0 77.0 70.0 33.3 49.0 56.0 28.0 98.0 20 7 8 12 11 15 Peristome diameter Vc Vp Vs Vh Ii Er 73,8 23.6 32.4 57.2 30.5 117.1 70 23.3 31.5 56.0 28.0 112.0 63 20.0 28.0 42.0 28.0 105.0 84 28.0 42.0 70.0 35.0 126.0 20 5 8 12 11 15 Stalk length Vc Vp Vs Vh Ii Er* 276,8 162.5 244.0 223.6 --- 2000.0 266 156.5 266.0 210.0 --- 2000.0 210 86.6 140.0 168.0 --- 2000.0 378 223.0 294.0 350.0 --- 2000.0 20 5 7 5 --- 1 Stalk width Vc Vp Vs Vh Ii Er* --- 2.7 --- --- --- 21.0 --- 3.3 --- --- --- --- 1.7 --- --- --- --- 3.3 --- --- --- --- 5 --- --- --- Adhesive disc diameter Ii 24.5 24.5 21.0 28.0 2 Table 4. Morphometric data on Vorticella convallaria (Vc), V. pulchella (Vp), V. striata (Vs), V. halophila (Vh), Intranstylum invaginatum (Ii), and Epistylis rotans (Er) in vivo. Spp., species; other abbreviations as in Table 2. 226.7 µS cm-1, dissolved oxygen concentration 6.3 mg L-1, temperature 8.6°C, pH 5.4. Remarks. Epistylis rotans was recorded by other authors in Hungary, Switzerland, Germany, Czech Republic, and Russia (Kahl, 1935; Nenninger, 1944-48; Stiller, 1971). This species was also found in México (Aladro Lubel et al., 2006), while it represents a new record in Argentina. Kahl (1935) and Stiller (1971) found this peritrich in plankton samples, while Nenninger (1944-48) recorded it on bryozoans and Lemna sp. Morphometric characteristics coincide with those observed by other authors from different geographic locations (Kahl, 1935; Nenninger, 1944-48), mainly in the Ciliates from Argentina Revista Brasileira de Zoociências 17(1): 41 - 62. 2016 58 typical shape of zooids. 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