Mobilina

Suborder (2) Mobilina Kahl, 1933

Syns. Mobilia,
Mobilida,
Mobiliida,
Mobilorina

Mobile forms, conical, cylindrical, or goblet-shaped, sometimes discoidal (orally-aborally flattened); dominant feature the aboral (basal) disc, a holdfast organelle of considerable complexity (denticulate ring, radiating myonemes, etc.); trochal band permanently ciliated; stalkless with scopula generally vestigial (though producing cilia in some forms); all species associated with some other organism as "host", often fresh-water or marine invertebrates (on integument or gills), but other groups (ciliates, amphibians, especially fishes), and other locations (digestive and urogenital tracts) may also be involved; fish-gill forms pathogenic in heavy populations.

Body cylindrical, often slightly tipped to one side; adoral spiral (buccal ciliature) turns ca. 400°, with wide radius; denticles of skeletal ring smoothly linked, ca. 20 in number; compact macronucleus; no cortical rings; ectosymbionts of fresh-water turbellarians and marine polychaetes and molluscs (gill surfaces). Family URCEOLARIIDAE Dujardin, 1840

Body cylindrical or barrel-shaped, with slightly bulging apical end; adoral spiral of ca. 400°, with radius like that of aboral adhesive disc; denticles smoothly linked, ca. 20 in number; macronucleus bulbous with two arms (roughly H-shaped); cortical rings present; widespread symbiont on gills of marine molluscs and on scattered other invertebrates (e.g., on spines of sea urchins). Family LEIOTROCHIDAE Johnston, 1938

Body conical, tapered apically; adoral spiral of ca. 360°, with greatly reduced radius, and buccal ciliature relatively inconspicuous; denticles smoothly but densely linked, numerous (35-55); cortical rings in evidence; some scopulary cilia present, and two trochal bands; macronucleus ribbon-like, with thick "nodes" and L-shaped; endocommensals of holothurian echinoderms. Family POLYCYCLIDAE Poljansky, 1951

Body conical, tapered apically; adoral spiral of ca. 360°, with greatly reduced radius, and buccal ciliature relatively inconspicuous; highly specialized infundibular area, with bulbous expansion posteriorly, etc.; denticles smoothly but densely linked, quite numerous (30-40); cortical rings and some scopulary cilia present; macronucleus compact, discoidal; intestinal symbionts of a terrestrial prosobranch snail. Family TRICHODINOPSIDAE Kent, 1881

Body cylindrical, barrel-, or goblet-shaped, occasionally slightly tapered apically or flattened into discoidal or hemispherical form; adoral spiral ranges from turn of 180° to 2-3 nearly full circles, always with wide radius (matching that of aboral adhesive disc); buccal ciliature conspicuous; denticles complex, often linked via hooks and/or spikes, generally 15-40 in number (but approaching 60 in several genera); no scopulary but often marginal cilia; macronucleus sausage- to horseshoe-shaped (sometimes compact); numerous species, widely distributed and found in diversity of hosts (e.g., Trichodina: others often with higher host-specificity): other ciliates and integument of various aquatic invertebrates, plus mantle cavity of land gastropod molluscs, to skin, urinary bladder, and especially gills of marine and fresh-water fishes and a few amphibians. Family TRICHODINIDAE Claus, 1874

Body cylindrical, often slightly tipped to one side; adoral spiral (buccal ciliature) turns ca. 400°, with wide radius; denticles of skeletal ring smoothly linked, ca. 20 in number; compact macronucleus; no cortical rings; ectosymbionts of fresh-water turbellarians and marine polychaetes and molluscs (gill surfaces).	*Family URCEOLARIIDAE* Dujardin, 1840**
Body cylindrical or barrel-shaped, with slightly bulging apical end; adoral spiral of ca. 400°, with radius like that of aboral adhesive disc; denticles smoothly linked, ca. 20 in number; macronucleus bulbous with two arms (roughly H-shaped); cortical rings present; widespread symbiont on gills of marine molluscs and on scattered other invertebrates (e.g., on spines of sea urchins).	*Family LEIOTROCHIDAE* Johnston, 1938**
Body conical, tapered apically; adoral spiral of ca. 360°, with greatly reduced radius, and buccal ciliature relatively inconspicuous; denticles smoothly but densely linked, numerous (35-55); cortical rings in evidence; some scopulary cilia present, and two trochal bands; macronucleus ribbon-like, with thick "nodes" and L-shaped; endocommensals of holothurian echinoderms.	*Family POLYCYCLIDAE* Poljansky, 1951**
Body conical, tapered apically; adoral spiral of ca. 360°, with greatly reduced radius, and buccal ciliature relatively inconspicuous; highly specialized infundibular area, with bulbous expansion posteriorly, etc.; denticles smoothly but densely linked, quite numerous (30-40); cortical rings and some scopulary cilia present; macronucleus compact, discoidal; intestinal symbionts of a terrestrial prosobranch snail.	*Family TRICHODINOPSIDAE* Kent, 1881**
Body cylindrical, barrel-, or goblet-shaped, occasionally slightly tapered apically or flattened into discoidal or hemispherical form; adoral spiral ranges from turn of 180° to 2-3 nearly full circles, always with wide radius (matching that of aboral adhesive disc); buccal ciliature conspicuous; denticles complex, often linked via hooks and/or spikes, generally 15-40 in number (but approaching 60 in several genera); no scopulary but often marginal cilia; macronucleus sausage- to horseshoe-shaped (sometimes compact); numerous species, widely distributed and found in diversity of hosts (e.g., Trichodina: others often with higher host-specificity): other ciliates and integument of various aquatic invertebrates, plus mantle cavity of land gastropod molluscs, to skin, urinary bladder, and especially gills of marine and fresh-water fishes and a few amphibians.	*Family TRICHODINIDAE* Claus, 1874**