Chaetonotus christianus (Schwank, 1990)
Most likely ID: n.a.
Synonym: n. a.
Sampling location: Simmelried
Phylogenetic tree: Chaetonotus christianus
- body slender with parallel sides
- length on average 215 µm
- head trilobate, median pleurae in a rudimentary form, posterior pleurae strongly prominent
- furca 25 µm long, adhesive tubes 15 µm long
- dorsally 21–25 longitudinal rows, 55–60 transverse rows of densely spaced scales
- scales tricuspid to arrow-shaped, with distal incision
- spines 2-3 µm except for 5-8 pairs of long spines at base of toes (5-12 µm)
- ventrally 12 longitudinal rows of keel scales and 2 long terminal keels
- pharynx cylindrical.
- intestine bipartite with an annular anterior section (golden brown in reflected light)
I found Chaetonotus christianus in March 2008 in Simmelried among decomposing plant masses at the bottom of the water. The species is very rare. After 2009 I have not been able to find any more specimens. In my other locations I have not detected Chaetonotus christianus so far. The identification is easy because of the very elongated spines at the base of the toes (s. figs. 3 and 4) which safely prevents a confusion with other species. Schwank & Bartsch, 1990 (s. Literature) describe the species as heat-loving and occuring from May to September. Since I found my specimens in March, this period must be extended.
Fig. 1 a-c: Chaetonotus christianus. L = 226 µm. A freely swimming specimen in ventral view (a) and lateral view (b, c). Obj. 40 X.
Fig. 2 a-b: Chaetonotus christianus. L = 226 µm. Two focal planes of the head from dorsal view. Obj. 100 X.
Fig. 3: Chaetonotus christianus. L = 226 µm. Dorsal view of the mid-body and posterior end. Note the strongly elongated spines at the base of the toes. Obj. 100 X.
Fig. 4: Chaetonotus christianus. L = 226 µm. Dorsal view of a strongly squashed specimen. Obj. 100 X.
Fig. 5: Chaetonotus christianus. L = 226 µm. The dorsal scales in the region from the head to mid-body in detail. Obj. 100 X.