As is common with the Irmelshausen line of the family, they commonly go by the last of their given names. August Hans Karl Reinhard von Bibra went by Reinhard or often just used the initial “R.” professionally. A professional soldier with the so called “K. und K” (Kaiserlich und Königlich ) army which refers to the Dual Monarchy of the Austrian Kaiser and the Hungarian Konig. Retired as a Oberst (colonel). At his death he was recognized at the family senior and held the empty title of the Erb-Untermarschall of the former duchy of Franconia (at least the Würzburg portion). As to the question as to who was the eldest male member of the family, they didn’t seem to include members outside continental Europe.
His writings include:
Anleitung zu Hand- und Finger-Gelenk- Übungen als Vorbereitung für die Handhabung der Waffen. (Manual of exercises for the joints of the hand and fingers, as a preparation for themanual of arms.) 16 pp. Wien 1892
Reinhard Freiherr von BIBRA, Die Schlacht bei Würzburg am 3. 9. 1796, in: AHVUfr 39, 1897, S. 221-252 ( Battle of Würzburg was fought on 3 September 1796 between an army of the Habsburg Monarchy led by Archduke Charles, Duke of Teschen and an army of the First French Republic led by Jean-Baptiste Jourdan.)
Reinhard Freiherr von BIBRA, Beitrag zur Geschichte der Kissinger Heilquellen “Rakoczy” und “Pandur”, in: AHVUfr 47, 1905, S. 165-209
Reinhard von BIBRA, Curia Kaulbenberg. Geschichte eines Würzburger Domherrenhofes, in: AHVUfr 51, 1909, S. 199-273
Reinhard von BIBRA, Kaiser Friedrich III. in Würzburg 1474, in: AHVUfr 65, 1926, S. 1-51
Carl ERDMANN, Ein Nürnberger offizielles Geschichtswerk über die Grumbachischen Händel, in: AHVUfr 65, 1926, S. 53-62
Reinhard von Bibra: Bodenlauben bei Bad Kissingen – Geschichte der Burg und des Amtes. Weinberger, Bad Kissingen 1903.
As of March 2022, he is referenced too in the English Wikipedia article on Knight of the Golden Spur (Hungary). (As a side note, Wilhelm von Bibra is very prominent in Knight of the Golden Spur (Holy Roman Empire)).
The Würzburg historian, Reinhard Freiherr von Bibra (1845–1926), in his study of Charles IV coronation (1916) published an image of the potential badge worn by the knights on their hats (a buttercup with golden spur and egret feathers), but he did not support it with sustainable historical sources. His aim goes back to some older descriptions telling that the Hungarian knights of golden spur wore a small gold spur not just on their boots, but beneath their hat buttercups, as well.
After his death that was a short report:
Nachruf auf Reinhard Freiherr von Bibra (Historiker, † 1926).
Autor(en): Henner, Theodor
Quelle: Jahresbericht / Historischer Verein von Unterfranken und Aschaffenburg
Fundstelle: (1926/27) 5-7
Bibliographie: Fränkische Bibliographie
The historical inventory book in Bavaria in the Irmelshausen section, credits him for illustrations.
Additionally, various illustrations by him on historical objects, places and people are credited to him.