First description of epizoic ciliates on Bathyporeia including undescribed species.
Hardly visible with the naked eye, flourishing communities of epibiont species are often present on macrofauna. Examining Bathyporeia (small crustaceans of few millimeters in size, abundantly present in marine and estuarine waters) from Dutch waters showed that peritrich ciliates were present on 44% of the over 3500 specimens investigated. Although known for a range of other species including crustaceans, peritrich ciliates on Bathyporeia, when present also often abundantly present, were not described in detail before. Only d’Udekem d’Acoz (2004) mentions the common presence of ramified colonies of peritrich ciliates on appendages of Bathyporeia in his paper on the genus.
We discovered several types including solitary and colony-forming specimens, of which the most common species appeared to be Zoothamnium nanum (an epibiont species known from other small crustaceans like Gamarus species). However, also a likely sofar undescribed species of the genus Epistylis appeared to be common, and another type of Zoothamnium (that might be an undescribed species) was observed.
Findings on infestation patterns for different Bathyporeia species for different waterbodies and years and possible implications for basibionts (hosts) and epibionts are presented and discussed in a paper published in Crustaceana: Wijnhoven et al. (2018). Taking into account the common presence and large abundances on a variety of macrofauna species, indicates that epizoic ciliates might play a more important role in ecosystem functioning than is now recognized and/or understood. There is still a whole world to discover!
Photographs of peritrich ciliates on Bathyporeia sp.; a) Typical colonies of peritrich ciliates (most likely Zoothamnium nanum) attached to a peduncle of an antenna from Bathyporeia pilosa (specimen stained with Rose Bengal and preserved in formaldehyde) (1000x magnification); b) Typical colonies of peritrich ciliates (most likely Zoothamnium nanum) in detail (on a specimen stained with Rose Bengal and preserved in formaldehyde) (4000x magnification); c) Individual and small colonies of alive Zoothamnium sp. on peduncles from antenna 2 of an alive specimen of Bathyporeia sarsi (1000x magnification); d) A singular alive specimen of Zoothamnium nanum on Bathyporeia sarsi (4000x magnification) with its cilia out; e) Singular alive peritrich ciliates on Bathyporeia pilosa (4000x magnification) showing a specimen without a spasmoneme (Epistylis sp.); f) Singular and couples of peritrich ciliates on Bathyporeia pilosa (4000x magnification) where the lower specimen belonging to the genus Zoothamnium lacks transverse folds (Zoothamnium sp.).
Wijnhoven, S., Zwiep, K.L., Hummel, H. (2018). First description of epizoic ciliates (Sessilida Stein, 1933) on Bathyporeia Lindström, 1855 (Peracarida, Amphipoda) and infestation patterns in brackish and marine waters. Crustaceana 91(2),133-152.
Other study cited:
d’Udekem d’Acoz, C. (2004). The genus Bathyporeia Lindström, 1855, in western Europe (Crustacea: Amphipoda: Pontoporeiidae). Zool. Verh. Leiden 348, 3-162.