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15 With the increasing contribution of data from other fields to the systematics of ciliates and the growing interest of biologists of all persua- sions in these microorganisms, we ought today to be familiar with a far greater range of terms than was required in the past. The information offered below not only provides, in the aggre- gate, a \u201cthumbnail sketch\u201d of most aspects in the overall biology of ciliates, but also permits use of the terminology in succeeding chapters with- out the need to reexplain it there. Our treatment is not exhaustive \u2013 and many commonly known anatomical, cytological, and ecological words are purposely omitted \u2013 but this compilation is longer than those presented for ciliates by Corliss (1959, 1961, 1979). It is principally based on those of Corliss (1979) and Lee (2002). An attempt has been made to keep the definitions or explanations succinct. However, brief descriptive comments have been added when terms are par- ticularly complicated or important. Almost always we have included information identifying the taxo- nomic group or groups of ciliates that possess or show the character or trait being described. Cross- referencing is frequently employed, either directly or indirectly by italicizing selected words in the definition. We have tried to point out controversies, present alternative meanings, and give synonyms. Furthermore, we have indicated our own preferences. For many words derived from Greek or Latin, we have provided the suggested plural. If a plural is not provided, it is generally acceptable to add an \u201cs\u201d or \u201ces\u201d to the singular, as appropriate. A number of morphological features are illustrated in the figures at the end of this chapter, and are indicated by a direct reference to the labelled structure in the figure and its part (e.g., Kd, Fig. 2.1A). Glossary A Aboral : away from the oral region ; in ciliatology almost always used in the most extreme sense, meaning at the opposite (usually antapical) pole from the (other) end (usually apical) of the body bearing the mouth; but \u2013 as in the case of peritrichs \u2013 the aboral pole is not necessarily the posterior pole of the organism, functionally and/or morpho- logically and/or evolutionarily (Ab, Fig. 2.8Aj). Abyssal : pertaining to the great depths of the ocean well beyond the continental shelf. Accessory Comb : a conspicuous ridge lying bet- ween the oral polykinetids, especially in tintinnids. Acellularity Concept : once popular hypothesis that protozoa, being individually complete (yet organized without tissues) cannot be cellular and thus must be considered noncellular or acellular organisms; it is now widely recognized that setting such eukaryotic cells as ciliates \u2013 notwithstanding their complex subcellular organization and extra- cellular specializations \u2013 apart from those of the \u201chigher\u201d metazoan groups is a decision basically neither defensible on (ultra)structural grounds nor judicious from a comparative evolutionary point of view; \u201ccell\u201d and \u201corganism\u201d need not be thought of as mutually exclusive terms. Chapter 2 Glossary of Terms and Concepts Useful in Ciliate Systematics 16 2. Glossary of Terms and Concepts Useful in Ciliate Systematics Acetabulum (pl. Acetabula ): term rarely used in ciliatology; see Sucker . Acidosome : vesicle filled with acid that fuses with the food vacuole to promote digestion; particularly used in Paramecium . Aciliferous : see Nonciliferous . Acmocyst : extrusome of rhynchodid phyllopharyn- geans . Acontobolocyst : see Trichocyst . Actinophore : structure bearing several, a bundle or a fascicle of suctorial tentacles ; characteristic of certain suctorians . Adhesive Disc : thigmotactic cup-shaped organelle at the aboral pole of mobiline peritrichs and some other ciliate (e.g., some spirotrichs ) used for attachment to the substratum, usually the surface of another organism that serves as host (Fig. 2.9Bg, 2.9Bh). Adhesive Organelle : often restricted to a secretory structure responsible for or structurally involved in production of a substance, other than cilia or some ciliary derivative, allowing the organism possess- ing it to adhere or attach to the substratum (e.g., the podite of dysteriid cyrtophorines ); but also see Holdfast Organelle (AO, Fig. 2.9Bf). Adoral Ciliary Fringe : see Frange . Adoral Ciliary Spiral : often applies to the spiral- ling pattern of the oral haplokinety and polykinety of peritrichs ; see Adoral Zone of Oral Polykinetids (Fig. 2.6b; ACS, Fig. 2.11B). Adoral Zone of Membranelles : see Adoral Zone of Oral Polykinetids . Adoral Zone of Oral Polykinetids : orderly arrange- ment of three or more oral polykinetids serially arranged typically along the left side of the oral region ; this arrangement has evolved by convergence in different groups of ciliates (e.g. heterotrichs , spirotrichs , colpodeans ) (Opk, Fig. 2.5Aa). Adult Form : generalized term; depending on the situation, the mature form, the parental form , the interfissional form, the sessile or sedentary form, the trophont . Afferent Canal : one of usually several cytoplas- mic channels transporting excreted fluid from the spongioplasm to a contractile vacuole ; also called a pulsating, nephridial, collecting, or radial canal; see Secretory Ampulla . Aire Sécante : see Secant System . Akontobolocyst : a synonym of spindle trichocyst; see Trichocyst . Algivorous : feeding on algae; see also Macro- phagous and Microphagous . Alpha Membranoid : see Membranoid . Alveolate(s) : protists whose pellicle is characterized by pellicular alveoli ; includes at least apicomplexans , ciliates, dinoflagellates , and colpodellids . Alveolocyst : an extension of the pellicular alveolus into the underlying cortex; particularly characteristic of nassulids . Alveolus (pl. Alveoli ), Pellicular : flattened vesicle or sac, bounded by a unit membrane , lying just beneath the surface or plasma membrane of the cell (organism) and above the epiplasm ; may occur in pairs in a given kinetosomal territory ; also known as a cortical vesicle (PA, Fig. 2.1B). Amacronucleate : without a macronucleus ; rare, unnatural, unstable condition, realizable only experimentally (e.g., in Paramecium ). Ambihymenium (pl. Ambihymenia ): condition of having oral ciliary \u201cmembranes\u201d completely surrounding the mouth-area; claimed by some workers to be the situation obtaining in a number of the cyrtophorine phyllopharyngeans. Amicronucleate : without a micronucleus , whether the loss has been brought about naturally or experi- mentally (e.g., in Tetrahymena ). Amitosis : nuclear division that results in the irregular distribution of chromosomes; a pathological kind of mitosis; however, unequal distribution of \u201cchromo- somal\u201d elements in the polyploid macronucleus of ciliates might be considered a kind of amitosis. Amphiparakinetal : parakinetal stomatogenesis in which the curved oral anlage intersects many pos- toral somatic kineties at two sites, enclosing few to many, short, non-proliferating kinetofragments ; found in some heterotrichs . Ampliploid : the nuclear condition in which there are numerous replicates of fragments of chromo- somes, sometimes as small gene-sized pieces, Glossary 17 produced by an amplification process and not by mitosis; characteristic of the ciliate macronucleus ; see Polyploid . Ampule : small, ovoid extrusome in the dorsal cortex of hypotrich spirotrichs (e.g. Euplotes ), and associated in clusters with kinetids of the dorsal bristle kinety ; may be involved in sexual interactions. Ampulla (pl. Ampullae ), Secretory : glandular organelle, generally multiple in number, which pro- duces a thigmotactic substance or structure in some cyrtophorines (see Adhesive Organelle ); also used for the collecting canal (or