LSJ (including the Revised Supplement) has an entry for ἀντιθάπτω:
'bury opposite:—Pass., aor. ἀντετάφην IG14.1721.'
This inscription from Rome (GVI 773, IGUR III 1241) is the only passage cited. In Kaibel's edition (as 573, with Dorville), the alleged verb was restored in line 4: δεξιὰ δ᾿ ἀντετάφη γηραὸς Ἱππομέδων·
Subsequent editors have remained closer to the reading of the stone itself (ΔΕΞΙΑΔΑΝΔΕΤΑΦΗ): δεξιάδαν δ’ ἐτάφη γηραὸς Ἱππομέδων·
LSJ (including the Revised Supplement) does not have an entry for δεξιάδην, but DGE does (on the grounds of this inscription and the antique lexicographic tradition).