Evolution and look-alikes
Trichopodiella faurei from the side, drawn from life. The arrow indicates small sacks (alveoli) in the outer skin (cortex).
The line on the right is 0.02mm (for comparison, human hair varies in width between 0.02 and 0.2mm). © J Gong, 2008
The Phyllopharyngea are unified by the support structures located behind the mouth.
Probably the most significant feature of the eukarya, compared with the bacteria and archaea, is the presence of the cytoskeleton. The eukarya evolved a network of structural rods to maintain cell shape, but more importantly to brace the cell and allow it to do mechanical work. Specifically, this cytoskeleton allows eukaryotic cells to pull the cell membrane into an internal pouch and thus ingest solid food.
In the Ciliophora the patch of membrane where ingestion takes place is called the cytostome. In the Phyllopharyngea, there is a basket of supporting rods (trichites) that form a structure equivalent to the metazoan throat. See also Pseudomicrothorax dubius.
The Phyllopharyngea are morphologically very diverse. We recognise 4 morphological groups: the cyrtophorids, the chonotrichs, the suctoria and the rhynchodins.
The molecular sequences derived from Trichopodiella faurei suggest that it is closely related to chonotrichs, although it is not as morphologically specialised as most members of the group. This means that the chonotrichs are a specialised group that might have evolved from within the cyrtophorids.
The small subunit RNA gene of the examined population also contains an intron - a DNA sequence that is removed after transcription - that shows a relationship to the Suctoria, supporting the common evolutionary origin of the group.
Look-alikes
The genus Trichopus was erected for a single species Trichopus dysteria (Claparède and Lachmann, 1859).
About a century later, Fauré-Fremiet (1957) added the second species T. lachmanni.
Since the generic name Trichopus was pre-occupied, Corliss (1960) suggested Trichopodiella to replace the invalid generic name. Since then, another 2 species of the genus Trichopodiella have been recognised (Deroux 1976).
Trichopodiella faurei n. sp. is most similar to T. lachmanni (Fauré-Fremiet, 1957) in terms of living morphology and behaviour including:
- oval body shape
- cell surface covered with cortical alveoli
- anchoring or attaching with mucous threads (Fauré-Fremiet 1957; Deroux and Dragesco 1968)
Nevertheless, the new species can be recognised by having:
- fewer somatic kineties (31–39 vs 40-50)
- nematodesmal rods (22–28 vs about 50)
- dikinetids in perioral kinety (16–19 vs 30–50)
- more contractile vacuoles (2–3 vs 1)
Both T. elongata Deroux, 1976 and T. pulex Deroux, 1976 have much reduced somatic kineties (<20 vs. 31-39 in T. faurei), thus both taxa can be separated from the new species.
The infraciliature of the type species Trichopodiella dysteria (Claparède and Lachmann, 1859) has yet to be described. However, T. faurei differs from T. dysteria in the following living morphological features:
- oval shape (vs. bilaterally compressed like Dysteria)
- possesses 2–3 contractile vacuoles positioned on the right of the ventral side (vs. single, dorsally situated near posterior end of cell)
