Dombeya Cav. (Malvaceae) as presently defined encompasses over 200 species and considerable morphological variation. Within the 2- to 3-carpellate Dombeya subg. Xeropetalum (Delile) K. Schum., almost half of the recognized species belong to Dombeya sect. Decastemon Planch., which is endemic to Madagascar and traditionally distinguished by its umbellate rather than cymose inflorescences. The most recent taxonomic treatment of this section recognized 47 species and numerous infraspecific taxa; an additional species referable to this group was recently described. The present treatment recognizes 41 species and 11 subspecies. Six species (D. micrantha Appleq., D. milleri Appleq. & Bosser, D. pauciflora Appleq., D. pilosissima Appleq. & T. Andriam., D. ratovosonii Appleq. & Bosser, D. vohemarensis Appleq.) are newly described, and one (D. ramiovensis (Arènes) Appleq. [≡ D. farafanganica Arènes subsp. ramiovensis Arènes]) is newly elevated to specific rank. Dombeya parvipetala Arènes, which (like D. pilosissima) has a small, dichotomously branching cymose inflorescence, is transferred from Dombeya sect. Xeropetalum (Delile) Planch. to Dombeya sect. Decastemon. The following names are transferred: D. ambalabeensis Arènes subsp. analavelonae (Arènes) Appleq. [≡ D. analavelonae Arènes], D. decanthera Cav. subsp. farafanganica (Arènes) Appleq. [≡ D. farafanganica], D. decanthera subsp. latipetala (Arènes) Appleq. [≡ D. farafanganica subvar. latipetala Arènes], D. subviscosa Hochr. subsp. ihosyensis (Arènes) Appleq. [≡ D. ambongensis Arènes var. ihosyensis Arènes], D. subviscosa subsp. sakarahae (Arènes) Appleq. [≡ D. ambongensis subsp. sakarahae Arènes]. Subsections formerly recognized are not reliably separable by morphology, so only six series are recognized, one of them newly described (Dombeya ser. Pentandrae Appleq.) and one newly recognized at that rank [Dombeya ser. Decantherae (Arènes) Appleq.]. Placement of species into series has been greatly rearranged, although some series remain heterogeneous and are used for convenience with no assertion of probable monophyly. Consistent with published reports of hybridization in other subgroups of Dombeya, a number of probable hybrid specimens are noted, several of readily identifiable parentage, but are not nomenclaturally recognized.