Acineta species in a fetid marine bacterial biofilm. Acineta foetida?
Update on the suctorian population growing in the foul-smelling bacterial biofilm that arose from decaying benthic seaweed/ algae in my sample from the near shore benthos of marine estuarine bay Shinnecock Bay. Compared to yesterday, the suctorian population is markedly decreased and less animated in terms of catching prey species, but many individuals now show a lorica or shell which was not at all evident in the previous day's slides. Some loricae do show ribbing as seen in Acineta foetida while others do not nor does the cell body tightly fill the lorica as in A. tuberosa. Perhaps this is indeed A. foetida in this fetid biofilm 🙂.
In addition, many cells appear to show marked transformation to the formation of several larval swarmers. Many forms are now distended with several ovoid larval swarmers, again with 5 oblique ciliary rows which is said to be specific for A. tuberosa (1). These are seen trying to escape the lorica or perhaps the cell membrane of the now defunct parent cells. In yesterday's sample, parent cells harbored only a single swarmer. Perhaps this is because yesterday's population was newly settled immature forms without a lorica.
The differential diagnosis remains between Acineta tuberosa and A. foetida, which Curds (1) considers a synonym of A. tuberosa while Dovgal (2) considers A. foetida to be a separate species. I now favor A. foetidus since there is ribbing of the lorica which is not tightly filled by the cell body as seen in A. tuberosa. Also, Maupas' 1881 depiction of the larval form in A. foetida (Curds fig. 3n after Maupas 1881) matches my material. Also the pattern of swarmer formation (fig. 3A from Curds after Maupas 1881) matches my material.
Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x objective and SPlan 100x oil objective plus variable phone cropping on Samsung Galaxy S9+.
- A revision of the Suctoria (Ciliophora, Kinetofragminophora). 1. Acineta and its morphological relatives. Colin R. Curds. Bull. Br. Mm. nat. Hist. (Zool.) 48(2): 75-129.
- Keys for identification of tentaculous infusoria (Ciliophora, Suctoria) of the Ukrainian fauna. Igor Dovgal. Vestnik Zoologii 2:1-42 Jan. 1996.
