Pré-visualização28 páginas
(in the inter- fissional stage); see Preoral kinety (Fig. 2.4O). Cirral Ciliature : see Cirrus . Cirromembranelle : name used by some workers for parts of the highly organized oral ciliature of certain colpodeans . Cirrus (pl. Cirri ): kind of compound somatic ciliature typical of hypotrich and stichotrich spiro- tricheans , though not exclusively found there; a composite tuft of cilia, few to >100, functioning as a unit, though typically with no special enveloping membrane, and tapering distally or else fimbriate; its infraciliary kinetosomes are also interlinked and joined to other cirral bases by connecting fibers or tracts of microtubules; characteristically, a cirrus is a thick conical locomotor organelle, but some are also occasionally of aid in food-gathering; occurring in lines or in groups in definite patterns on the ventral surface, with subtypes identifiable by their location (viz ., buccal, frontal, frontoventral, midventral, transverse (anal), caudal, and marginal) (Fig. 2.4M, 2.4N; Cir, Figs. 2.3Aj, 2.3Al, 2.5Ab, 2.7k). Cisterna (pl. Cisternae ): see mention under Endoplasmic Reticulum and Golgi Apparatus . Clade : a monophyletic lineage. Cladistics : the branch of systematics devoted to identifying clades . Clathrocyst : cytoplasmic extrusome in Didinium involved in production of the elaborate middle or mesocystic layer of the cyst wall (Fig. 2.9Cc). Clathrum : total abandonment of the term \u201cclathrum\u201d (Latin for \u201clattice\u201d) is here proposed; see Rhabdos . Glossary 23 Clavate Cilium (pl. Cilia ): short immobile cilia lacking the central pair of microtubules in their axoneme; allegedly sensory in function, occurring in a number of ciliates, typically in the brosse of hapto- rian litostomes (e.g., Didinium ) and prostomes , but also present in the scopula of many peritrichs ; also called stereocilium ; see Condylocilium . Clonal Life Cycle : see Life Cycle, Clonal . Clone : population of organisms established by cul- turing the descendants of a single individual. Cnidocyst : special kind of extrusome generally found in certain dinoflagellates but now (also) reported from several species of karyorelicteans ; in karyorelicteans, it appears to be a pear-shaped, laterally-flattened extrusome that contains a multiply coiled filament. Cnidotrichocyst : while a synonym for toxicyst , use of this term is not recommended. Code of Nomenclature : see International Code of Zoological Nomenclature . Collar : term used variously; the neck area between the often flared apical end and the body proper in chonotrichs ; variously differentiated region beneath the opening in the lorica and used as a diagnostic characteristic in taxonomy (e.g. loricate peritrichs , tintinnid spirotrichs ); an open or closed zone of oral polykinetids encircling the anterior end of choreot- richs (Figs. 2.6B; Col, 2.8Ae, 2.8Af, 2.8Ah, 2.11Ca). Collarette : apical, peristomial lip that circumscribes the retractable epistomial disc in many sessiline peritrichs ; equipped with a sphincter \u201cmuscle\u201d (or Myoneme ) (Colt, Fig. 2.11B). Collecting Canal : see Afferent Canal . Colony : assemblage of cells derived by fission from a founder individual; see definitions under major types (i.e., Arboroid, Catenoid, and Spherical ) (Fig. 2.8A, 2.8B). Commensal : see Commensalism . Commensalism : a symbiosis in which the symbiont benefits by the association but the host does not particularly suffer; endo- and ectocommensals exist in many groups; category sensu lato could include epibionts and symphorionts , typical forms in the life cycle of many attached or sessile ciliates, which live on the outside of their host; an inquiline may be considered a special kind of endocom- mensal. Compound Ciliary Organelle : see Compound Ciliature . Compound Ciliature : general term for all cilia- ture not comprised of single, separate or isolated individual cilia or of dikinetids of somatic cilia; various kinds, both somatic and oral in origin, occur throughout the phylum; particularly well developed in the spirotrichs (e.g. cirrus , mem- branelle , polykinetid ). Compound Oral Ciliature : compound ciliature found in the oral region . Compound Somatic Ciliature : compound cili- ature found in the somatic region . Concrement Vacuole : curious and quite complex subpellicular cytoplasmic inclusion, one to an organ- ism, containing refractile, probably mineral grains, having no opening, and sometimes strengthened by surrounding microtubules; characteristic of certain trichostome endocommensals; function unknown, but considered by some workers as a kind of statocyst. Condylocilium (pl. Condylocilia ): kind of clavate cilium found in hypotrich spirotrichs . Condylopallium : ovoid, bulb-like extension of the ventral right anteriormost part of the hypotrich spirotrich Certesia , containing a vesicle with dense granules; function unknown, but perhaps excretory or statocyst-like. Conjugation : reciprocal-fertilization type of sexual phenomenon in which a meiotic/mitotic product of the micronucleus is typically reciprocally exchanged between the two individuals, except in total conju- gation ; presumably occurs only between members of differing mating types; allegedly significant to both vitality of the clone and survival of the species, although the phenomenon is unknown (unobserved) in many ciliates from various groups; may involve iso - or macro - and microconjugants , with temporary (most widespread) or total (as in all peritrichs and chonotrichs) fusion of members of the pair; pre- and exconjugant stages are recognized; the process is always followed by fission ( s ) of the exconjugants. Conocyst : a small, cone-shaped extrusome , prob- ably a toxicyst , in the cortex of haptorians (e.g., Homalozoon and Loxophyllum ). 24 2. Glossary of Terms and Concepts Useful in Ciliate Systematics Constellation of Characters Principle : use of mul- tiple characters from diverse approaches or fields in assessment of differences or similarities between or among groups of organisms under comparative taxonomic study; its application helps overcome biases and prevents the extreme splitting likely when only very few characters \u2013 or data from but a single field \u2013 are used to draw conclusions concerning phylo- genetic and taxonomic relationships. Contractile Vacuole ( CV ): liquid-filled organelle (sometimes multiple), serving as an osmoregulator in the cytoplasm of nearly all ciliates; generally pulsates with regular frequency under natural conditions: grows (diastole) to a certain size and then \u201ccontracts\u201d (systole), typically emptying its contents, which may include dissolved \u201cwaste materials\u201d, to the exterior via one or more pores; the CV is more widespread in ciliates than the ( cytoproct, CYP); synonymous, but non-preferred terms, are water expulsion vesicle and nephridial apparatus (CV, Fig. 2.9Bf). Contractile Vacuole Pore ( CVP ): minute perma- nent opening in the pellicle , with argentophilic rim and a canal reinforced by microtubules through which contents of the contractile vacuole are expelled to the outside milieu; CVP\u2019s are cortico- type structures, characteristically stable in number and location and thus of diagnostic value in com- parative taxonomy; also known by non-preferred term \u2013 expulsion vesicle pore (CVP, Figs. 2.3Ad, 2.3Af, 2.3Ai, 2.4A, 2.4F, 2.4K, 2.7a, 2.7f, 2.7i, 2.7k, 2.11Aa). Convergent Evolution : development of similar characters separately in two or more groups that do not share a close common ancestry; such characters, preserved by natural selection, arising through adaptation to similar ecological pressures or habitats. Corona (pl. Coronae ): apical, cytostome-bearing extremity of the body of certain haptorians ; often