conioeca thomsen & ostergaard 2019 family acanthoecidae norris 1965 em. nitsche et al. 2011 (nudiform choanoflagellates) acanthoeca ellis 1930 enibas schiwitza, arndt & nitsche 2019 helgoeca leadbeater 2008 polyoeca kent 1880 savillea loeblich iii 1967 family stephanoecidae leadbeater 2011 (tectiform choanoflagellates) ?conion thomsen 1982 ?spiraloecion marchant & perrin 1986 acanthocorbis hara & takahashi 1984 amoenoscopa hara & takahashi 1987 apheloecion thomsen 1983 bicosta leadbeater 1978 calliacantha leadbeater 1978 calotheca thomsen & moestrup 1983 non desv. 1810 non spreng. 1817 non heyden 1887 cosmoeca thomsen 1984 crinolina thomsen 1976 non smetana 1982 crucispina espeland & throndsen 1986 diaphanoeca ellis 1930 didymoeca doweld 2003 kakoeca buck & marchant 1991 monocosta thomsen 1979 non monocostus schumann 1904 nannoeca thomsen 1988 parvicorbicula deflandre 1960 pleurasiga schiller 1925 polyfibula manton 1981 saepicula leadbeater 1980 saroeca thomsen 1979 spinoeca thomsen, ostergaard & hansen 1995 non poulsen 1973 stephanacantha thomsen 1983 stephanoeca ellis 1930 syndetophyllum thomsen & moestrup 1983 thomsenella özdikmen 2009 genomes and transcriptomes monosiga brevicollis genome the genome of monosiga brevicollis, with 41.6 million base pairs, is similar in size to filamentous fungi and other free-living unicellular eukaryotes, but far smaller than that of typical animals. in 2010, a phylogenomic study revealed that several algal genes are present in the genome of monosiga brevicollis. this could be due to the fact that, in early evolutionary history, choanoflagellates consumed algae as food through phagocytosis. carr et al. (2010) screened the m. brevicollis genome for known eukaryotic meiosis genes. of 19 known eukaryotic meiotic genes tested (including 8 that function in no other process than meiosis), 18 were identified in m. brevicollis. the presence of meiotic genes, including meiosis specific genes, indicates that meiosis, and by implication, sex is present within the choanoflagellates. salpingoeca rosetta genome the genome of salpingoeca rosetta is 55 megabases in size. homologs of cell adhesion, neuropeptide and glycosphingolipid metabolism genes are present in the genome. s. rosetta has a sexual life cycle and transitions between haploid and diploid stages. in response to nutrient limitation, haploid cultures of s. rosetta become diploid. this ploidy shift coincides with mating during which small, flagellated cells fuse with larger flagellated cells. there is also evidence of historical mating and recombination in s. rosetta. s. rosetta is induced to undergo sexual reproduction by the marine bacterium vibrio fischeri. a single v. fischeri protein, eros fully recapitulates the aphrodisiac-like activity of live v. fisheri. other genomes the single-cell amplified genomes of four uncultured marine choanoflagellates, tentatively called uc1–uc4, were sequenced in 2019. the genomes of uc1 and uc4 are relatively complete. transcriptomes an est dataset from monosiga ovata was published in 2006. the major finding of this transcriptome was the choanoflagellate hoglet domain and shed light on the role of domain shuffling in the evolution of the hedgehog signaling pathway. m. ovata has at least four eukaryotic meiotic genes. the transcriptiome of stephanoeca diplocostata was published in 2013. this first transcriptome of a loricate choanoflagellate led to the discovery of choanoflagellate silicon transporters. subsequently, similar genes were identified in a second loricate species, diaphanoeca grandis. analysis of these genes found that the choanoflagellate sits show homology to the sit-type silicon transporters of diatoms and have evolved through horizontal gene transfer. an additional 19 transcriptomes were published in 2018. a large number of gene families previously thought to be animal-only were found. gallery monosiga brevicollis under pcm salpingoeca under pcm salpingoeca sp. section under tem desmarella moniliformis colony under pcm codosiga colony under light microscopy sphaeroeca colony (approx. 230 individuals) under light microscopy.