Main Content
< Top page

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Pseudokephyrion

Pseudokephyrion Pascher (ref. ID; 4878)
  1. Pseudokephyrion auroreum Nicholls (ref. ID; 4878)
  2. Pseudokephyrion heverlense (Conrad) Conrad (Starmach, 1985) (ref. ID; 4878)
  3. Pseudokephyrion hyalinum Hilliard (Hilliard, 1966) (ref. ID; 4878)
  4. Pseudokephyrion poculiforme Ikavalko, Thomsen & Carstens, 1996 (ref. ID; 4878 original paper)

Pseudokephyrion poculiforme Ikavalko, Thomsen & Carstens, 1996 (ref. ID; 4878 original paper)

Diagnosis

Solitary species with heterokont flagellation. The longer flagellum is approximately equal in length to the lorica. The short flagellum is visible only in EM. The cell most entirely fills the simple, bowl-shaped lorica which consists of delicate delicate fibrillar threads. The lorica (5.5-6.3x5.5-5.8 um) is smoothly rounded posteriorly, and with parallel sides. There are no structures for attachment. The cell has a single chloroplast. (ref. ID; 4878)

Remarks

The taxonomical concept of Bourrelly (1968) is followed here with respect to distinguishing between the genera Dinobryon Ehrenberg, Kephyrion Pascher and Pseudokephyrion Pascher. Species of Dinobryon are usually larger than those allocated to the two other genera mentioned. However, morphologically P. poculiforme is reminiscent of D. urceolatum Reverdin (Starmach 1985: 9-11x9-11 um). The main criterion for distinguishing between the genera Pseudokephyrion and Kephyrion is the presence or absence of a second, short flagellum. This separation of genera was based on light microscopical evidence only, and has to be considered dubious. It is now well known that most often the true heterokont nature of many small, loricate chrysophytes is not revealed in LM. Our study supports this because the presence of the shorter flagellum in P. poculiforme was confirmed only after TEM examination. Future studies on the genera Kephyrion and Pseudokephyrion may give appropriate reasons for combining these genera. However, for the time being this new species will be allocated other genus Pseudokephyrion. P. poculiforme is with regard to morphological simplicity somewhat similar to Pseudokephyrion hyalinum Hilliard (Hilliard, 1966) and P. heverlense (Conrad) Conrad (Starmach, 1985). The straightsided nature of the lorica yet clearly differentiates P. poculiforme from both of these species. The overall most strikingly similar taxon is Pseudokephyrion auroreum Nicholls, a small species described from Ontario (Nicholls 1977). However, in addition to its slightly smaller size (4-5x3-4 um) the delicate P. auroreum lorica narrows towards the opening. Due to its hyaline nature the lorica of P. auroreum is difficult to observe in unstained preparations (Nicholls 1977). In P. poculiforme the fibrillar construction of the lorica renders possible the recognition of this taxon even in LM whole mounts. (ref. ID; 4878)

Etymology

poculiformis, poculiforme" = cup-shaped. (ref. ID; 4878)