Pseudomaryna australiensis nov. gen., nov. spec. and Colpoda brasiliensis nov. spec., two new colpodids (Ciliophora, Colpodea) with a mineral envelope

Pseudomaryna australiensis and Colpoda brasiliensis were discovered in floodplain soils from Australia and Brazil and studied in vivo and in silver preparations. They have a common feature, viz., a sheath of clay (mineral) particles embedded in a slimy matrix. Such sheaths, which evolved convergently in various ciliates, are termed “mineral envelopes” and make cells appear like inorganic soil particles, possibly protecting them from predators. The new genus Pseudomaryna belongs to the family Colpodidae and is characterized by the preoral suture which extends for the whole body length right of the oral opening due to the widely projecting left side ciliary rows. Maryna antarctica Foissner, 1993 has the same ciliary pattern and is thus transferred to the new genus: Pseudomaryna antarctica (Foissner, 1993) nov. comb. Both, P. australiensis and P. antarctica are small (length 25–60 μm), reniform soil ciliates differing in the macronuclear structure (with vs. without central nucleolus), the mineral envelope (present vs. absent), and details of the somatic and oral ciliary pattern. Colpoda brasiliensis is also a small ciliate (about 33 × 18 μm), differing from the congeners by the mineral envelope and a combination of ordinary features, viz., the location and structure of the macronucleus and the preoral ciliary pattern. Probably, it is related to the Colpoda steinii group.