Protospathidium
Protospathidium Dragesco & Drageso-Kerneis, 1979 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Gymnostomata: Order Haptorida: Family Spathidiidae (ref. ID; 2013)
[ref. ID; 2013]
Body outline shape elongate, posterior bluntly rounded, apical region ending obliquely in an unciliated ridges as in Spathidium but here the ridge is very short. Ciliation uniform in a few parallel longitudinal rows which bend obliquely apically to meet the ridge where they are paired for a short distance. There is a short dorsal brush. Macronucleus in several parts distributed throughout the body. Contractile vacuole single and terminal. Feeds on flagellates.
Most easily mistaken for Spathidium in which genus the kineties neither bend nor are paired apically.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)
- Protospathidium muscicola Dragesco & Drageso-Kerneis, 1979 (ref. ID; 2128)
- Protospathidium serpens (Kahl, 1930) Foissner, 1981 (ref. ID; 2128, 2846) reported author and year? (ref. ID; 191)
- Protospathidium terricola Foissner, 1997 (ref. ID; 2846)
Protospathidium serpens (Kahl, 1930) Foissner, 1981 (ref. ID; 2128, 2846) reported author and year? (ref. ID; 191)
Descriptions
Shape slender, slightly to distinctly sigmoidal, inconspicuously flattened laterally, general appearance thus cylindroid. Macronucleus rather variable, three modifications were found in 79 specimens analyzed: nodular (48 cases), rod-like (27 cases), ellipsoidal (4 cases). Micronuclei of variable position, i.e. not at fixed site and attached to or rather distant from macronucleus. Contractile vacuole terminal, with 3-6 excretory pores. Extrusomes invariable rod-shaped with rounded ends; arranged in 2-3 rough circles around central depression of oral bulge. Cortex colourless, flexible, in population from Marion Island (Antarctica) with about 5 rows of minute (< 0.3 um), pale granules between each 2 ciliary rows. Cytoplasm rather hyaline, contains some 1-4 um sized, colourless fat droplets, obviously digestion products from ingested heterotrophic flagellates and/or bacteria because no ciliates were present when P. serpens flourished. Moves slowly. Somatic infraciliature without peculiarities, dorsal brush, however, highly differentiated. Anterior cilium of first dikinetid distinctly elongated in each brush row, easily confused with cilia from circumoral kinety segments which, however, lack distal inflation; kinety 3 extends above mid-body, as indicated by shortened cilia, although basal bodies not paired in posterior brush half. Oral bulge conspicuous, i.e. refractile and compact because packed with extrusomes, oval in frontal view, centre usually distinctly depressed, rarely almost most flat. Segments of circumoral kinety distinctly separate, adhere to somatic ciliary rows, associated with long, fine nematodesmata forming wedge-shaped bundles. (ref. ID; 2128)
Macronuclear shape also highly variable: nodular in 60% (n=92), rather widely wound in 38%, and rod-like in 2% of interphase specimens of population I; narrowly tortuous in 58% (n=106), nodular in 34%, rod-like in 5%, U-shaped in 2%, and ellipsoidal in 1% of population II. Micronuclei slightly more numerous but smaller in population I than II, often adjacent to or in shallow depression of macronucleus; position in population II more constant than in population I, that is, usually one micronucleus each near anterior and posterior ends of macronucleus. Extrusomes rod-shaped, in living specimens about 5 um long. Food vacuoles about 10-20 um across, possibly containing heterotrophic flagellates. Movement slow, rotates about main body axis when swimming, glides between soil particles. Dorsal brush as specified by Foissner (1996), that is, row 3 extends almost to mid-body with anterior portion composed of paired bristles and with posterior portion consisting of monokinetids with cilia about 2 um long. (ref. ID; 2846)
Cyst:
Resting cyst brownish, wall about 2 um thick, highly refractile, contains conspicuous, compact granules causing cyst surface to become studded and, respectively, honey-combed in lateral and surface view. Cytoplasm finely granulated macronucleus tortuous (ref. ID; 2128)
Specimens encysted within about 15 min when transferred from the raw culture to Eau de Volvic (French table water). Resting cysts about 25 um across. (ref. ID; 2846)
Comments
The populations of P. serpens from Wilkes Land are similar to those described from Signy Island (Foissner 1996) and Europe (Kahl 1930; Foissner 1981). However, the European specimens have slightly fewer (about eight on average) somatic kineties than those for the Antarctic and sub-Antarctic. Spathidium sp. found by Thompson (1972, fig.6) and Thompson and Croom (1978) in melt water pools and in a lake on Anvers Island off the Antarctic Peninsula is similarly sized and shaped as P. serpens, but possesses a very long and often loosely coiled macronucleus and 14-17 somatic kineties. The specimens identified as P. serpens by Berger an others (1984) possess 15-30 macronuclear nodules and are thus very likely conspecific with P. muscicola, as already supposed by Foissner (1996). Although the latter differs only by the fragmented macronucleus from P. serpens, it should be classified as valid species because P. serpens has a single, vermiform nucleus. (ref. ID; 2846)
Measurements
Size in vivo about 70-100x12-18 um. Resting cysts 28-32 um (x=29.8, n=8). (ref. ID; 2128)
Size highly variable, in vivo 43-117x8-25 um, however, usually about 65-90x15-20 um. (ref. ID; 2846)
Descriptions
Shape depended on nutritional state, slenderly to rather broadly cylindroid with neck usually distinctly narrowed and curved dorsally; cross-section circular, neck and oral bulge laterally somewhat flattened. Oral bulge slightly concave and short, but usually slightly wider than neck, often somewhat inclined to ventral side, packed with extrusomes. Macronucleus in living specimens about 30-38x12-22 um, basically reniform but rather variable in detail; sausage-like (28%, n=115), C-shaped (25%), ellipsoidal (24%) or helically wound (23%); contains spherical to ellipsoidal nucleoli 1.5-4 um across. Macronucleus globular to slightly ellipsoidal, adjacent to macronucleus. Contractile vacuole in posterior end, with up to nine excretory pores. Extrusomes rod-like with rounded ends, 4-8 um, usually about 5 um long in living specimens, in oral bulge and cytoplasm; fusiform extrusomes found only in cytoplasm are very likely developmental stages. Cortex flexible and colourless, with four to five, rarely up to eight rows of minute (about 0.2 um), pale granules between each two ciliary rows; granules stain reddish with methyl green-pyronin but are not extruded. Cytoplasm with numerous small, colourless granules, some far droplets up to 4 um across, and food vacuoles containing bright green globes (algae?, up to 13 um across), many pale green spherical to ellipsoidal (up to 6x3 um) cyanobacteria, flagellates, and ciliates (for example, Odontochlamys wisconsinensis). Rotates about main body axis when swimming with neck usually curved dorsally; glides between and on soil particles, often recoils and changes direction. Circumoral kinety oval in frontal view, discontinuous, that is, composed of dikinetidal fragments adhering to anterior ends of somatic kineties and separated from each other by indistinct gaps, which are often difficult to recognize, especially on right side. Dorsal brush three-rowed, rows 1 and 2 almost of same length and mainly composed of paired cilia; row 3 consists of a short, dikinetidal anterior portion and a long, monokinetidal tail with about 2.5 um long bristles terminating near mid-body; brush rows at posterior end often with one to six apparently unciliated basal bodies before continuing backwards as normal somatic kineties. Cilia of brush dikinetids highly differentiated, clavate, anterior cilium usually longer (about 2-4 um) than posterior (approximately 1-2.5 um), in rear portion of brush gradually shortened; two to eight distinctly elongated cilia (6-8 um) in anterior portion of row 3. (ref. ID; 2846)
Cyst: Specimens may encyst rapidly, that is, the fist cyst appeared 6 min after transfer from the raw culture to Eau de Volvic; after 30 min all (about 10) individuals were encysted. About one-week-old resting cysts 49-52 um in diameter (average=50, n=4), wall about 1.5 um thick, smooth, vitreous. Cytoplasm with may about 1-um-sized granules and tortuous to C-shaped macronucleus containing spherical nucleoli. (ref. ID; 2846)
Comments
The Antarctic specimens match the original description by Foissner fairly well. They are, however, slightly larger (average= 101x32 vs. 81x23), have fewer (average= 17 vs. 21) ciliary rows, and the fragments of the circumoral kinety are less distinctly separated from each other. Thus, impregnated specimens, particularly when not properly oriented, are easily confused with Spathidium claviforme Kahl, 1930. However, a reinvestigation of the neotype population of S. claviforme, which invariably has a continuous circumoral kinety and 10-13 ciliary rows, revealed that the Antarctic specimens belong to P. terricola. Protospathidium serpens is shorter (about 70-80 um on average) and has fewer (average=8-13) somatic kineties. Protospathidium muscicola possesses a multinodular macronucleus and only 7-12 ciliary rows. (ref. ID; 2846)
Measurements
Size highly variable, in vivo about 134x31 um. (ref. ID; 2846)