"86a Brigada Mixta" Topic

I was doing some research on the International Brigades, in particular the 20th Battalion which served with the 86th Mixed Brigade. Then I came across this information on the Wikipedia page for the Brigade:

In January 1938, as a result of heavy restructuring, the 20th International Battalion was split into three battalions, the 20th, 21st and 22nd. At the same time three of the Carabineros battalions were transferred to the 222nd Mixed Brigade so that the only remaining Spanish battalion was the 'Pablo Iglesias nr 2 Battalion'. Thus the 86th Mixed Brigade became one more International Brigade, with 2,338 international fighters of which 57 were leaders and officers and 29 were sub-officers. The newly-formed battalions were led by Militia Majors Ernst Düdel, Paul Odpadlik, Cuni Bernhardt and Adolf Rach, while the machine gun company was led by Georg Prunzings.[2]
The restructured brigade returned to the front line at the Sierra del Castaño and the Peña del Águila, replacing the 103rd Mixed Brigade. It saw action during the attack against the rebel positions at Villafranca de Córdoba covering the front in the Guadalmellato and Miradero positions.[2] However, in order to satisfy the demands of the Non-Intervention Committee, the foreign members of the brigade were withdrawn on 1 October 1938 and were replaced by battalions of Spanish conscripts. Being composed of local soldiers, thenceforward the 86th Mixed Brigade was wrapped up as an International Brigade.[6]"

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The source being: Carlos Engel, Historia de las Brigadas Mixtas del E. P. de la República, 1999

This is the first information I have seen on these two battalions – the XXI & XXII – I don't believe that I have come across them in any of the standard sources on the IBs. Has anyone else heard of them before?