Dichotomous key to Collothecidae

1 Infundibulum with five very long lobes resembling arms, ~ trunk length or longer; arms either stout with setae in whorls or slender with long slim setae not in whorls; setae always at right angles to arms; clear gelatinous tube; body length ≤1500 µm; sessile; oviparous. (Fig. 3A,B)................................................... Stephanoceros Ehrenberg, 1832 [In light of the fact that some members of the genus Collotheca also possess long lobes (e.g., Collotheca judayi Edmondson, 1940; Collotheca tenuilobata (Anderson, 1889)), Meksuwan et al. (2013) have recommended that the status of both genera be re-evaluated.]

1’ Infundibulum with lobes absent or short to long, sometime knobbed at the terminus; long setae usually present extending from infundibular margin of the lobes; setae never in whorls and never held at right angles to arms; cilia often present; clear tube may be embedded with algae or with debris; body length ~100–2,500 µm; sessile or planktonic; oviparous. (Fig. 3C,D)......................................................................................... Collotheca Harring, 1913 [In some species (e.g., C. judayi) setae are absent and the entire inside surface of the infundibulum is ciliated (Edmondson 1940). While most are sessile, Collotheca libera (Zacharias, 1894), Collotheca mutabilis (Hudson, 1885), Collotheca pelagica (Rousselet, 1893), and Collotheca polyphemus Harring, 1914 are planktonic, Collotheca ornata (Ehrenberg, 1830) occurs in planktonic, benthic, and sessile forms, including on the carapaces of cladocerans (Sebestyén 1957), and Collotheca crateriformis (Offord, 1934) is benthic. Nearly all produce a clear gelatinous tube; none are colonial, but may colonize substrata forming dense groupings (Wallace & Edmondson 1986).