Family Conochilidae Harring, 1913

Family Conochilidae was separated into two genera ( Conochilus and Conochiloides) by Hlava (1904). However, Ruttner-Kolisko (1974) argued that the separation was not warranted and subsumed Conochiloides back into genus Conochilus . While this practice has continued (Fontaneto & De Smet 2015; Koste 1978), some workers have not followed this change (Bielańska-Grajner et al. 2015; Pontin 1978; Stemberger 1979). Segers & Wallace (2001) added Conochilopsis to the family; it comprises a single species, originally described as a member of the genus Lacinularia (Vidrine et al. 1985) . Species secrete a gelatinous matrix that affords protection from the predatory rotifer Asplanchna girodi Guerne, 1888 (Gilbert 1980). In Conochilus hippocrepis (Schrank, 1803), colony size increases in diameter (number of individuals) in relation to the size of a sympatric predatory copepod (Diéguez and Balseiro 1998). The gelatinous matrix is often colonized by bacteria (including cyanobacteria), algae, and protozoans (Fig. 5) (Balvay & Druart 1995). Occasionally population crashes occur due to parasites invading the perivisceral cavity (blastocoel) (Ruttner-Kolisko 1977). Colonies tumble (rotate) while swimming.

The etymon for this genus (G., cono, a cone + G., chilus, a lip) was given by Ehrenberg (1834) because the apical field—the fleshy region surrounded by the corona—is inflated by two cone-shaped, lip-like structures located on either side of the mouth (Fig. 6). This structure appears to be depicted in individuals (2 of 7) in figure 3 of Conochiloides (Lacinularia) causeyae by Vidrine et al. (1985).

Diagnosis. Apical field with two inflated, cone-shaped, lip-like structures located centrally or dorsally. Corona circular to horseshoe-shaped, as a double ciliated band (trochus and cingulum) with a prominent ventral gap in the cilia present or not. Body shape conical; illoricate integument with unsegmented foot lacking toes. Paired ventral (lateral) antennae separate or fused to various degrees, within or below coronal field; dorsal antenna absent or minute. Two dorsal eyes beneath corona. U-shaped intestine, anus exiting just above the margin of the gelatinous matrix. Trophi malleoramate: rami symmetrical or slightly to strongly asymmetrical; unci with 3–6 club-shaped (clavate) teeth near fulcrum, (number and form of clavate teeth may be different on each side); numerous, thin accessory teeth beyond clavate ones (distal to fulcrum). Planktonic, either solitary or small to large colonies (5 to>400 or more individuals per colony). Animals clustered within a gelatinous mass produced by glands in foot. Oviparous.