Oopsacas minuta, an Amoebozoan Animal: Genetic Evidence Supports a Case of Multicellular Evolution from Amoebozoan Ancestry

Comprehensive molecular analysis of Lyssacinosida glass sponge Oopsacas minuta with bidirectional BLAST searches produced long-alignment, 80–85% sequence identity matches with nucleariid amoebozoans (Nuclearia thermophila, N. simplex, N. pattersoni) across 18S rRNA, 28S rRNA, and mitochondrial markers. Cross validation reveals strong affinities to Fonticula alba, including across a 5.2 kb pre-mRNA processing factor alignment. Recursive BLAST analysis revealed additional strong matches between Oopsacas minuta and Amoebozoa, predatory fungi, complex protists, Excavata, and basal holozoans.

Expanded validation of glass sponge species confirmed these strong matches are not present in other glass sponges. Further, testing showed that even closely related Lyssacinosida species either did not share the matches at all or only presented weak alignments.

These genetic signatures, combined with the existing understanding of Oopsacas minuta’s unusual physiology and genome, seem to indicate that Oopsacas minuta represents an amoebozoan lineage that achieved permanent multicellular organization independently of metazoan developmental pathways, exhibiting morphological convergence toward sponge-like architecture while retaining fundamental amoebozoan genetic identity.

Journal: https://osf.io/ur79d/ DOI 10.17605/OSF.IO/UR79D

Issue One Project Data: https://osf.io/69whf/ DOI 10.17605/OSF.IO/69WHF

French translation: (link).