adelphotaxon

From Ancient Greek ἀδελφός (adelphós, “brother”) + taxon.

adelphotaxon (plural adelphotaxa)

1. (taxonomy, systematics) A sister taxon.
   • 1987, Peter Ax, The phylogenetic system: the systematization of organisms on the basis of their phylogenesis:

     In the structure of the phylogenetic system, as in every hierarchical ordering, a sequence of ranks between the taxa of the individual levels is necessarily linked with the sequence of hierarchical levels. Here the following law applies: the adelphotaxa of any given level of coordination have identical rank.

   • 2012, Peter Ax, Multicellular Animals:

     When justifying the monophyly of system unities and working out their ground patterns, we usually, more or less immediately, draw upon the subordinated adelphotaxa.