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|Title: ||Morphogenesis in the Marine Spirotrichous Ciliate Apokeronopsis crassa (Clapare`de & Lachmann, 1858) n. comb. (Ciliophora: Stichotrichia), with the Establishment of a New Genus, Apokeronopsis n. g., and Redefinition of the Genus Thigmokeronopsis|
|Authors: ||Shao, Chen|
AL-Rasheid, Khaled A.S.
AL-Quraisy, Saleh A.
|Keywords: ||Cell regeneration|
|Issue Date: ||2007 |
|Publisher: ||International Society of Protistologists|
|Citation: ||Journal of eukaryotic microbiology: vol 54(4); 392-401|
|Abstract: ||Morphogenetic events during the division of the marine spirotrichous ciliate, Apokeronopsis crassa (Clapare`de &
Lachmann 1858) n. comb. were investigated. Compared with members of the well-known genera Thigmokeronopsis, Uroleptopsis, and
Pseudokeronopsis, A. crassa has one row of buccal cirri, high number of transverse cirri, clearly separated midventral rows, lacks
thigmotactic cirri and a gap in adoral zone, its undulating membranes (UMs) anlage forms one cirrus and marginal rows and dorsal kineties
form apokinetally during division. All these characteristics indicate that this organism represents a new taxon at the generic level, and
hence a new genus is suggested, Apokeronopsis n. g. It is defined as thus: Pseudokeronopsidae with Pseudokeronopsis-like bicorona of
frontal cirri and one marginal row on each side; one row of two or more buccal cirri in ordinary position; two midventral rows distinctly
separated, hence of cirri that are not in a typical zig-zag pattern; high number of transverse cirri, caudal cirri absent, and frontoterminal
cirri present; thigmotactic cirri absent, many macronuclear nodules fuse into many masses as well as marginal and dorsal kineties form
apokinetally during morphogenesis. At the same time, the genus Thigmokeronopsis Wicklow, 1981 is redefined, and one new combination,
Apokeronopsis antarctica (Petz, 1995) n. comb. is proposed. The morphogenetic events of A. crassa are characterized as follows:
(1) In the proter, the adoral zone of membranelles and UMs are completely renewed by the oral primordium. The UM anlage is formed
apokinetally on the dorsal wall of the buccal cavity and is hence clearly separated from the frontoventral-transverse (FVT) cirral anlagen in
the proter. (2) Frontoventral-transverse cirral anlagen are generated de novo in the outermost region of the cortex to the right of the old
UMs. (3) A row of buccal cirri arises from FVT cirral streak I. (4) The marginal rows and dorsal kineties originate de novo in both dividers;
no caudal cirri are formed. (5) The last FVT-streak contributes two frontoterminal cirri. (6) The many macronuclear nodules fuse into
many masses (about 50 segments) during division, unlike a singular or branched mass as described in other urostylids.
Key Words. Cell regeneration, Pseudokeronopsidae, Spirotrichea, systematics, Urostylida.|
|Appears in Collections:||King Saud University Initial Collection|
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