Pelagohalteria
Pelagohalteria Foissner, Skogastad & Pratt, 1988 (ref. ID; 1599 original paper)
Class Oligotrichea Butschli, 1887: Family Halteriidae Claparede & Lachmann, 1858 (ref. ID; 4906)
[ref. ID; 1599]
Diagnosis; Body globular or obovoid; oral apparatus with eccentrically located buccal cavity and collar and buccal membranelles; somatic bristle complexes each composed of a vertically and a horizontally oriented row of cilia; movement rotating and jumping. (ref. ID; 1599)
Systematic position; Pelagohalteria belongs to the family Halteriidae Claparede & Lachmann, 1858, and is very similar to the genus Halteria Dujardin, 1841. The equatorial somatic cilia ("bristles") of Halteria are, however, arranged in single, roughly vertically oriented rows, whereas Pelagohalteria has a second horizontally arranged row of cirri-like cilia close below each vertical bristle complex. This character is shared at least by one other species of the genus, Halteria cirrifera Kahl, 1935, which is thus transferred to the new genus, Pelagohalteria cirrifera (Kahl, 1935) n. comb. (ref. ID; 1599)
Type species; Pelagohalteria viridis (Fromental, 1876) n. comb. (ref. ID; 1599)
- Pelagohalteria cirrifera (Kahl, 1932) Foissner, Skogstad & Pratt, 1988 (ref. ID; 4488, 4609, 4613, 4906 redescribed paper) reported author and year? (ref. ID; 1599, 1629)
Syn; Halteria cirrifera Kahl, 1935 (ref. ID; 1599, 4609, 4906); Halteria grandinella var. cirrifera Kahl, 1932 (ref. ID; 4609, 4613, 4906)
- Pelagohalteria viridis (Fromental, 1876) Foissner, Skogstad & Pratt, 1988 (ref. ID; 1599 redescribed paper, 1629, 4613)
Basionym; Halteria viridis (ref. ID; 1599)
Pelagohalteria cirrifera (Kahl, 1932) Foissner, Skogstad & Pratt, 1988 (ref. ID; 4488, 4609, 4613, 4906 redescribed paper) reported author and year? (ref. ID; 1599, 1629)
Synonym
Halteria cirrifera Kahl, 1935 (ref. ID; 1599, 4609, 4906); Halteria grandinella var. cirrifera Kahl, 1932 (ref. ID; 4609, 4613, 4906)
Improved diagnosis
In vivo 25-34x22-34 um. Spherical to obovoid, anteriorly slightly conical, posteriorly hemispherical. 14-16 anterior and 6-7 ventral polykinetids. 7 bristle complexes. (ref. ID; 4906)
Redescription
Shape anteriorly slightly constricted, posteriorly broadly rounded. Cross section circular. Intermembranellar ridges between anterior membranelles. Bean-like macronucleus filled with spherical to ellipsoidal nucleoli. Micronucleus adjacent to macronucleus, usually not stained with protargol. Contractile vacuole on the left side. Cytoplasm hyaline, with some small green enclosures. Feeds on pennate diatoms (7x4 um). Movement slowly rotating, interrupted by jumps. Bristle complexes in groobes, connected by fibrils, cilia 16 um long. Bristle complex invariably consisting of 4 vertical and 4 horizontal kinetosomes. Anterior polykinetids consisting of 3 rows of kinetosomes, bases connected by system of fibres. Ventral polykinetids each composed of oral cavity. Oral primordium originates ventrally between first and last bristle complex. (ref. ID; 4906)
Comments
The population described here is very similar in size, position of the contractile vacuole and structure and number of bristle complexes to Pelagohalteria cirrifera (Kahl, 1935) Foissner, Skogstad & Pratt, 1988; thus it is identified with the species. The rather spherical to obovoid body shape differs, however, from the descriptions of Kahl (1932) and Liebmann (1962). A closely related species in P. viridis (Fromentel, 1876) Foissner et al., 1988, which differs from P. cirrifera mainly by its symbiotic green algae, less conspicuous horizontal bristle rows, a slightly higher number of bristle complexes and ventral polykinetids. (ref. ID; 4906)
Type specimens
Neotype as 1 slide of protargol impregnated cells has been deposited in the collection of microscope slides in the Zoologische Museum Hamburg. (ref. ID; 4906)
Pelagohalteria viridis (Fromental, 1876) Foissner, Skogstad & Pratt, 1988 (ref. ID; 1599 redescribed paper, 1629, 4613)
Basionym
Halteria viridis (ref. ID; 1599)
Descriptions
Diameter in vivo 20-30 um. Body globular to heart-shaped, round in frontal view, constricted at level of adoral zone of membranelles, obliquely truncated anteriorly, broadly rounded posteriorly. Pellicle thin, fragile; most individuals burst at contact with the cover glass. Macronucleus centrally located, bean-like, filled with large, globular chromatin bodies. A micronucleus has not been found in the protargol-impregnated cells. Contractile vacuole left of buccal cavity, just anterior to equator. Cytoplasm colorless, filled with many small (1-4 um) shining globules and ca. 30 symbiotic algae, most grouped in two clumps left and right of the pharynx. Algae 4-6 um in diameter, with a distinct cell wall, a pyrenoid, and a red stigma, as in those found in Halteria chlorelligera. Thus, the algae do not belong to the genus Chlorella but no another unidentified taxon. Eight to 11 (mostly nine) bristle complexes, numbered from right (number I) to left in the equator of cell. Each complex consists of six to 11 ciliated kinetosomes, about half of them in an almost vertically oriented row, the others horizontally oriented; although cilia somewhat like cirri in SEM, in vivo not fused and act independently. Great variability in number and arrangement of kinetosomes in bristle complexes. Kinetosomes of horizontal rows always in straight lines; kinetosomes of vertical rows often randomly arranged. Cilia of bristle complexes ca. 25 um long. Half of individuals with at least one distally bifurcated bristle. Cilia of collar adoral membranelles ca. 15 um long, apparently not fused after preparation for SEM study. Each collar membranelle three rows of kinetosomes and connected by numerous fibrils with neighboring membranelles. Buccal cavity inconspicuous; short paroral membrane at its right border; at left, seven to nine buccal membranelles, each consisting of two rows of kinetosomes. Silverline system fine-meshed (mesh diameter ca. 1 um in nonciliated regions and ca. 0.5 um near bristle complexes). (ref. ID; 1599)
Comments
The original description of P. viridis is very incomplete. There are, however, a few characters which support our identification. First, Fromentel mentioned that the somatic cilia are thick, which is unusually in members of the genus Halteria but typical for the "cirri" of Pelagohalteria. Second, Fromentel noticed a green color of his species, which suggests that it possessed symbiotic green algae ("zoochlorellae"). Third, the size (ca. 20 um) also agrees rather well with out measurements. Considering the very poor drawing of Fromentel, any identification is more or less arbitrary. We prefer, however, to redescribe an old species with more precise characteristic rather than create a new one if there are at least a few appropriate features in the old description. Pelagohalteria viridis differs from P. cirrifera by its symbiotic green algae and the less conspicuous horizontal bristle rows ("cirri"). Although neither Kahl (1932) nor Dragesco & Dragesco-Kerneis (1986), who found a few individuals of this species in Africa, provided details on the structure of the "cirri", one might suppose from their descriptions and drawing that they were composed of at least two closely associated rows of cilia. Pelagohalteria viridis also bears some resemblance to Halteria chlorelligera Kahl, 1935, a species with symbiotic green algae, but which is sapropelic and is probably a true Halteria species because Kahl (1932) did not mention a bipartition of the somatic bristle complexes. The occurrence of bifurcated bristle cilia and symbiotic green algae are described in Halteria bifurcata Tamar, 1968. Tamar, however, definitely states that the cilia of the bristle complexes of H. bifurcata are arranged in single vertical rows and that the symbiotic algae, which have no stigma, are of the Chlorella-type. We have no explanation why the kinetosomes of the horizontal bristle complexes are more regularly arranged than those of the vertical bristle complexes. This phenomenon needs closer examination in different populations and in clone cultures. (ref. ID; 1599)