Pentahymena
Pentahymena Foissner, 1994 (ref. ID; 4854 original paper)
[ref. ID; 4854]
Diagnosis; Medium sized Jaroschiidae with five differently shaped oral ciliary fields and distinct preoral suture containing many brick-shaped adoral organelles. (ref. ID; 4854)
Comparison with related genera; The new genus apparently belongs to the Jaroschiidae, an unusual group of bryometopid colpodids, which diagnosed Foissner (1993) as follows: "Moderately small to medium sized, completely ciliated Bryometoida. No postoral suture. Oral apparatus very complicated, consists of more than 3 differently structured elements. At right and proximal slope of vestibulum several vestibular kineties and paroral membrane-like structures comprising many short ciliary rows. At left vestibular slope several brick-shaped adoral organelles. Silverline system presumably very tightly meshed". Unlike Jaroschia sumptusoa Foissner, 1993, P. corticicola has a distinct preoral suture containing brick-shaped adoral organelles. This resembles the colpodid order Bryophryida. Thus, it can not be excluded that Pentahymena and Jaroschia belong to this order. Unfortunately, the type species of the genus Bryophrya is still insufficiently known. Thus, a proper classification of the Bryophryidae and Jaroschiidae is not yet possible. Both, Pentahymena and Jaroschia have been found in bark and are probably restricted to this biotope. (ref. ID; 4854)
Etymology; Composite of "penta" (five) and "hymen" (membrane); both Greek. Feminine. The name refers to the five membranous structures forming the oral infraciliature. (ref. ID; 4854)
Type species; Pentahymena corticicola (ref. ID; 4854)
- Pentahymena corticicola Foissner, 1994 (ref. ID; 4854 original paper)
Diagnosis
In vivo 130-160x70-100 um, reniform. Single ellipsoid macronucleus, several micronuclei. Contractile vacuole with collecting canals at posterior end. About 55 distinctly spiralling somatic kineties. Vestibulum deep and narrow, on right slope about 8 vestibular kineties, on left slope and in preoral suture approximately 25 brick-shaped adoral organelles. Right oral ciliary field hook-shaped and longer than slightly crescentic left field, both composed of many tightly spaced, short kineties. Anterior end of postoral kineties sharply bent back and densely ciliated, forming membranoid structures along left oral ciliary field. (ref. ID; 4854)
Descriptions
Only few, mediocrely impregnated specimens were found in the Chatton-Lwoff slides. Material was to scanty for protargol impregnation. Morphometry is thus incomplete and the description based mainly on cells studied in vivo and impregnated with silver carbonate. Shape resembling Colpoda maupasi and/or Bryophrya spp., viz. right and dorsal side convex, left and ventral side slightly indented at oral apparatus, both ends broadly rounded. Inconspicuously flattened dorso-ventrally. Prepared cells often broadly spindle-shaped. Macronucleus distinctly ellipsoid to slightly reniform, in middle third of cell. About 4 micronuclei near macronucleus, in vivo 4 um in diameter and surrounded by distinct membrane. Contractile vacuole with 2 collecting canals at posterior end, discharge via tubular excretory pore in centre of posterior pole. Cortex slightly furrowed by somatic kineties, flexible, contains plate-like layer of disc-shaped mitochondria about 1.2 um in size. No extrusomes recognizable in vivo and in silver carbonate strains. Cytoplasm colourless, postorally usually crammed with (i) up to 50 um sized food vacuoles having loose content, some even appear empty making cytoplasm looking strongly vacuolated; (ii) many greasily shining granules 1-3 um in diameter, and (iii) some yellowish, about 2x1 um sized crystals concentrated in posterior end around contractile vacuole. Feeds on ciliates (e.g. Colpoda), which are quickly digested. Moves slowly, glides and/or rotates about longitudinal axis. Somatic kineties distinctly spiralling, composed of slightly inclined, ciliated dikinetids. All commence around oral apparatus and along postoral suture, and most extend to posterior end of cell. Kineties originating at left oral ciliary fields slightly wider spaced than preoral ciliary rows. Oral apparatus in anterior ventral third. Vestibular opening slit-like, vestibulum deep and narrow, obliquely oriented to longitudinal axis of cell, contains oral ciliary field except of those found in preoral suture. Oral infraciliature very complicated, comprises 5 clearly distinguishable ciliary fields on vestibular walls and in preoral suture. First (right most) oral ciliary field composed of about 8 vestibular kineties on right slope of vestibulum. Vestibular kineties consist of closely spaced dikinetids, producing heavily beating ciliary plate; dikinetids more loosely and zigzag-like arranged in anterior portion of kineties than in posterior one where they form very tightly spaced, slightly irregular rows. Some vestibular kineties may be shortened, but most end and proximal vestibular vertex and do not extend posteriad as normal somatic kineties. Second oral ciliary field on inner portion of right vestibular wall, consists of many short, oblique kineties forming long, hook-shaped structure extending from anterior edge of vestibular opening beyond its posterior vertex, i.e. into tubular portion of vestibulum; proximal portion curved back to vestibular opening and distinctly narrowed, i.e. composed of single row of dikinetids. Third oral ciliary field on inner portion of left vestibular wall, about as long as vestibular opening, i.e. shorter but broader than second ciliary field, slightly crescentic, left edge uneven because of different length of kineties. Fourth oral ciliary field on exterior portion of left vestibular wall and in preoral suture, consists of about 25 brick-shaped adoral organelles extending from proximal vertex of vestibular opening to anterior pole of cell; individual organelles composed of 2-5 kineties with 2-3 basal bodies each. First oral ciliary field formed by anterior ends of postoral kineties which bend back in acute angle and polymeraize dikinetids to membranoid structures. Silverline system tightly and irregularly meshed, in posterior body portion with distinct argyophilic line between some somatic kineties. (ref. ID; 4854)
Comparison with related species
No other species have been found in the literature which could be identical with P. corticicola. Superficially, Jaroschia sumptuosa and Bryophrya spp. resemble P. corticicola, but their oral structures are clearly different, which is easily recognizable even in living cells (Foissner 1993). (ref. ID; 4854)
Etymology
"corticicola" (Latin, living in bark) refers to the biotope. (ref. ID; 4854)
Type location
Bark of an Acasia tree by the ranch house "La Casona" in the Santa Rosa National Park, Costa Rica, W85 degrees 40', N10 degrees 50'. (ref. ID; 4854)
Type specimens
Two holotypes and two paratypes of P. corticicola as four slides of silver nitrate (Chatton-Lwoff and Klein technique) impregnated cells have been deposited in the collection of microscope slides of the Oberosterreichische Landesmuseum in Linz, Austria. (ref. ID; 4854)