The genus Kiransus Makhan, 1994 erected for a hydrochid species, K. aschnaae Makhan, 1994, with a unique and extremely modified tergum 8 (= 'sternum 5' of Makhan), is placed as a junior synonym (syn. n.) of Hydrochus Leach, 1817, in which it represents a highly derived, subordinate clade, here referred to as the 'Hydrochus aschnaae species group'. A redefinition of this clade is proposed, based on the discovery of three new species, Hydrochus tuberculatus sp. n. from Burkina, H. nigeriensis sp. n. from Nigeria and H. ensifer sp. n. from Sudan. Structural peculiarities in the abdominal apex of Hydrochidae are outlined and attention is called to certain features of phylogenetic importance.