A taxonomic study of the species with nutant, pleurotoid and cyphelloid basidiomata of the genus Arrhenia in the Iberian Peninsula is presented. This study is based on the examination of recent specimens collected in the field and from dried herbarium collections. Five species and one variety of this genus are recognized on the basis of morphological and ecological features: Arrhenia acerosa var. acerosa, A. acerosa var. tenella, A. auriscalpium, A. lobata, A. retiruga and A. spathulata. Arrhenia auriscalpium is new to Spain, where it is not restricted to alpine zones of the Eurosiberian region and is more common in the Mediterranean region than previously reported. In contrast, A. acerosa var. tenella currently is known from the Eurosiberian subalpine belt and represents the first report to the Iberian Peninsula, and A. retiruga is known only from the mesomediterranean to supramediterranean belts of the Mediterranean region. Arrhenia acerosa var. acerosa, A. lobata and A. spathulata are widespread in both the Eurosiberian and the Mediterranean regions. Non-Iberian materials of A. acerosa var. tenella and A. spathulata also were studied for comparison. Cyphella cochlearis var. subsessilis, Dictyolus lagunae, Leptoglossum muscigenum var. azonum and Pleurotellus acerosus var. tenellus are lectotypified. Cyphella cochlearis var. subssesilis, Dictyolus lagunae and Leptoglossum muscigenum var. azonum are synonymized with Arrhenia spathulata, and Cyphella cochlearis var. auriformis is placed in synonymy with A. auriscalpium. These taxa are illustrated, described and discussed, based on Iberian material with emphasis on features of the basidioma, pigment of the pileipellis, presence or absence of clamps and shape and size of the basidiospores. A diagnostic key also is given.