"This one is really yellow!"
- Macrobiotus coronifer and very close relatives
In the year 1859 the famous German zoologist Christian Gottfried Ehrenberg (1795 - 1876)
published an article with the title: "Contribution to the assessment
of persisting life in Alpine heights up to 20,000 feet".
He did invest considerable effort in the illustrations. E.g. his
engraving showing Macrobiotus furcatus from the Monte Rosa mountain
measures 26 cm in width (!). But still - remember, we are in the 19th century -
it is a b&w illustration. Ehrenberg is compelled to add some verbal comment:
The colour of the fresh specimen is vividly yellow.
What does he mean by fresh specimen? Tardigrade literature
in general tends to neglect colour. Scholarly biology has a strong tendency
to fix any living cell by means of formaldehyde thus preserving most
structural details - hopefully. One of the first victims in the process
of fixation is colour. So, if the colour is not documented in some way
before the fixation, it will be lost. On the other hand, many tiny structural
details like the fine pattern of the cuticula will persist in the permanent
preparation for decades and therefore will be preferred in species characterisation.
The famous Ehrenberg did not fail to note the intensively yellow colour and
we will show it to you now:
Intensively yellow tardigrade,
typically found in mountain regions,
e.g. the Bavarian Alps. Still image
captured from a video film.
Body length ca. 600 µm.
The claws ... have an almost perfectly disc-shaped dented base
... the exact geometry of which was difficult to determine.
We have looked at the feet of our Bavarian specimen as well and
did encounter similar (?) focusing problems:
Intensively yellow tardigrade.
Detail: claws of the last pair of legs.
Still image from a video clip. Dark field illumination.
Intensively yellow tardigrade.
Same detail as before, slightly higher magnification. Bright field illumination.
Ehrenberg added an illustration of the eggs which are highly
characteristic and which look identical as those of our yellow tardigrade:
Intensively yellow egg of the yellow tardigrade.
Maximum diameter ca 150 µm.
And here is a view of the pharyngeal bulb:
Same tardigrade as before.
Detail showing pharyngeal bulb, bucchal tube and stylets. Two spheroid macroplacoids, no Komma.
All the details on our photomicrographs look identical to those on the
Ehrenberg Macrobiotus furcatus illustrations.
But in 1928, when describing the properties of the species Macrobiotus furcatus
the tardiologist Ernst Marcus doesn't mention the conspicuous colour at all.
In 1903 Ferdinand Richter claims the existence of a new species
now called Macrobiotus coronifer . It has exactly the same properties
as Macrobiotus furcatus, with chrome yellow storage cells in incident light
and ochre storage cells in transmitted light. Again, the species name seems to be as
fugitive as the colour of the fresh specimen: in 1981 Macrobiotus coronifer is
going to be renamed to Adorybiotus coronifer .
Don't panic, tardigrade taxonomy is a full-time job and we are amateurs.
In the next issue we will show Ehrenberg's fine original illustrations. Stay tuned!
Christian Gottfried Ehrenberg: Beitrag zur Bestimmung des stationären
mikroskopischen Lebens in bis 20,000 Fuß Alpenhöhe.
p. 455. Abhandlungen der Königlichen Akademie der Wissenschaften,
Ernst Marcus: Bärtierchen. p. 135 [description of Macrobiotus furcatus].
Ernst Marcus: Tardigrada. p. 153 [description of Macrobiotus furcatus]. Berlin 1936.
Ferdinand Richters: Nordische Tardigraden [description of Macrobiotus coronifer on p. 171].
Zoologischer Anzeiger 27 (1903) 168-172.
Hieronim Dastych: The Tardigrada of Poland. S. 69 - 71 [Description
of Adorybiotus coronifer, with excellent drawings]. Warsaw 1988.
Walter Maucci: Fauna d'Italia: Tardigrada. p. 227 - 230
[description of Adorybiotus coronifer]. Bologna 1986.
Walter Maucci, Giulio Ramazzotti: Adorybiotus gen. nov.: nuova posizione
sistematica per Macrobiotus granulatus Richters, 1903 e per
Macrobiotus coronifer Richters, 1903 (Tardigrada, Macrobiotidae).
Mem. Ist. Ital. Idrobiol., Pallanza 39 (1981) 153 - 159.
© Text, images and video clips by
Martin Mach (email@example.com).
Water Bear web base is a licensed and revised version of
the German language monthly magazine Bärtierchen-Journal .
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