A review of the Malagasy endemic genera Anaceros, Hovanoceros and Malgaceros (Opiliones: Laniatores: Biantidae)

CLAUDIA V. MAMANI,; WILLIANS LOURENÇO PORTO; ABEL PÉREZ GONZÁLEZ

Simposio; AAS Virtual Summer Symposium; 2020

Anaceros Lawrence, 1959, Hovanoceros Lawrence, 1959 and Malgaceros Lawrence,1959, are three biantid genera endemic to Madagascar. Anaceros was originallydescribed to accommodate four species, whereas Hovanoceros and Malgaceros weredescribed as monotypic. Before now, species in these genera were known only from theoriginal descriptions, in which important taxonomic characters (e.g. male genitalmorphology) were not described. After examining 250 specimens from the CaliforniaAcademy of Sciences collection, we provide a redescription of all previously knownspecies and describe six new species. As well as describing the exomorphology, weprovide a detailed description of the male genitalia, and of microdetails documentedthrough Scanning Electron Microscopy. Our results show that the characters previouslyused to define the genera (e.g. ocularium size) are highly variable among species andhave no utility for generic delimitation. We propose Hovanoceros and Malgaceros asjunior synonyms of Anaceros and consequently propose their new combinationsrespectively. Also, we emend the diagnosis of the genus Anaceros. This study revealsjust a small part of the rich and uncharted diversity of litter-dwelling Malagasy opilionids.Because of the high level of micro-endemicity observed, we predict that many newspecies of this group remain to be discovered on the island.