A revision of Boletellus sect. Ixocephali

Taxa included in Boletellus section Ixocephali sensu Singer are re-evaluated and species limits are clarified in a morphological context. In this revision, we recognize four distinct morphological species: B. jalapensis, B. elatus, B. longicollis, and B. singerii. Among these, we have ascertained that the concept of B. jalapensis was broadened to include another taxon (B. singerii) that was eventually recognized as distinct. Details of spore morphology that include size and shape also show that the precise longitudinal alignment and apical fusion or non-fusion of the costate ornamentation distinguishes two species pairs. These pairs occur on either side of the Pacific basin and include one velate and one non-velate species each: B. longicollis, B. elatus (E Asia) and B. jalapensis, B. singerii (America). Now that discrete morphological entities are clarified and recognizable, phylogenetic hypotheses can be attempted to test these concepts and perhaps infer the monophyly of section Ixocephali when appropriate sequence data are available from newly collected, properly vouchered and viable specimens.