Collothecidae Bartoš, 1959

Davies, Natalie, Lafleur, Alexandre, Hochberg, Rick, Walsh, Elizabeth J. & Wallace, Robert L., 2024, Key to sessile gnesiotrochan rotifers: Families, monospecific species in Flosculariidae, species of Atrochidae, Conochilidae, and Limnias, Zootaxa 5397 (4), pp. 497-520 : 503

Family Collothecidae Bartoš, 1959

Of the two genera comprising this family, Collotheca is numerically dominant; Stephanoceros has only two recognized species. Yet this family is commonly ignored in ecological studies and relatively few studies have been done on the general anatomy of these forms to come to meaningful conclusions regarding evolutionary trends and thereby their phylogenetic relationships ( Edmondson 1944; Hochberg 2014; Hochberg et al. 2019; Meksuwan 2015; Meksuwan et al. 2013; Segers et al. 2010; Yang et al. 2019, 2021).

Unfortunately descriptions of the Collothecidae , especially in the morphology of lobes on the infundibulum and arrangement of cilia and/or setae on its margin, are inconsistent. Lobe morphology varies to such an extent that a definitive description covering all variations is nearly impossible. The issue of what constitutes a lobe presents a serious problem, at least in some species of Collotheca . For example, in the species Collotheca edmondsoni Bērziņš, 1951 there are three regions on the infundibular margin that possess setae, but these regions may not be recognized as lobes. Also definition and usage of the terms cilia and setae are inconsistent in the literature. In general we have retained the term(s) used by the original author; however, when the original descriptions are unclear, we use the terms cilia and setae to indicate short and long structures, respectively. Additionally, there has been no systematic study of the movements of the setae ( Wright 1958).

Collothecaceans are raptorial and feed on a wide variety of prey, including diatoms, photosynthetic and colorless flagellates, dinoflagellates, ciliates, and rotifers ( Bērziņš 1951; Bērziņš 1952; de Beauchamp 1912; Koste 1970; Valerio 1975; Wright 1958).

Diagnosis.Infundibulum bearing long setae and/or short cilia lining part or all of infundibular edge; infundibulum without lobes (the entire head lying within a single plane) or elaborated into lobes, bulbs, and/or tentacles (arms); these vary in number (0–7); mouth central; vestibulum present. Most sessile, but several planktonic species. Foot of sessile forms ending with an adhesive disk or peduncle. Tube, when present, a clear gelatinous matrix.