Diagnosis. Eohypsibiidae with a rigid straight, buccal tube. The mouth is tubular, not trumpet-shaped as in Bertolanius Özdikmen, 2008 and Eohypsibius Kristensen, 1982. Lateral on the buccal tube are 2 to 6 hook-shaped appendages present for insertion of the stylet muscles. Ventral strengthening bar absent, but cuticular enforcement can be seen as a thin line. Mouth opening with 14 peribuccal lamellae. Claws of the Eohypsibiidae type. Eggs ornamented and deposited free.
Composition. Austeruseus faeroensis, nov. sp. (type species), Austeruseus balduri, nov. sp. and Austeruseus rokuri, nov. sp.
Etymology. austerus (latin) – rigid, pertaining to the rigid buccal tube.
Differential diagnosis. The genus Austeruseus can be distinguished from Bertolanius and Eohypsibius by the buccal-pharyngeal apparatus, which is slender (pt buccal tube width 8.3–14.4) and straight throughout its length, as opposed to being wide and trumpet-shaped in Bertolanius and Eohypsibius. Austeruseus does not possess posterior annulations on the buccal tube as seen in the genus Eohypsibius. The presence of 2 to 6 hook-shaped apophyses for the insertion of stylet muscles, compared with crest-shaped dorsal and ventral apophyses for the insertion of stylet muscles with two pairs of caudal hooks (Eohypsibius) or crest shaped apophyses for the insertion of stylet muscles with a single pair of caudal hooks (Bertolanius).