The genera Davus O. Pickard-Cambridge, 1892, Metriopelma Becker, 1878, and Schizopelma F. O. Pickard-Cambridge, 1897 are redefined. The genus Acentropelma Pocock, 1901 is removed from synonymy with Stichoplastus Simon, 1903, and the genus Eurypelmella Strand, 1907b is removed from synonymy with Schizopelma F. O. Pickard-Cambridge, 1897 gen. rest. The holotype specimens of Davus fasciatus O. Pickard-Cambridge, 1892, Metriopelma zebratum Banks, 1909, Metriopelma drymusetes Valerio, 1982, Metriopelma breyeri Becker, 1878, Schizopelma bicarinatum F. O. Pickard-Cambridge, 1897, and conspecifics of Cyclosternum pentaloris Simon, 1888 are redescribed. Hapalopus ruficeps Simon, 1891 is removed from synonymy with Cyclosternum pentaloris Simon, 1888 and, along with Cyclosternum fasciatus O. Pickard-Cambridge, 1892 and Metriopelma zebratum Banks, 1909, are transferred to the genus Davus (O. Pickard-Cambridge, 1892) comb. nov. Davus santos sp. nov. is described. Davus ruficeps is regarded as senior synonym of Metriopelma zebratum syn. nov., Metriopelma drymusetes Valerio, 1982 is regarded as junior synonym of Davus fasciatus O. Pickard-Cambridge, 1892 syn. nov. Davus mozinna Estrada-Alvarez, 2014 is regarded as junior synonym of D. pentaloris syn. nov. The specimen of Metriopelma breyeri Becker, 1878 from the Natural History Museum, London, is formally nominated as topotype because the holotype is missing (see Discussion). Metriopelma familiare (Simon, 1889) and Metriopelma ledezmae Vol, 2000 are tentatively transferred to the genus Cyclosternum Ausserer, 1871 comb. nov., while Metriopelma coloratus Valerio, 1982 and Metriopelma variegatus (Caporiacco, 1955) are transferred to the genus Hapalopus Ausserer, 1875 combs. nov. Metriopelma velox Pocock, 1903, Lasiodora trinitatis (Pocock, 1903), and L. trinitatis pauciaculeis (Strand, 1916) are transferred to the genus Pseudhapalopus Strand, 1907a combs. nov. Metriopelma spinulosum O. Pickard-Cambridge, 1899 is transferred back to the restored genus Acentropelma Pocock, 1901 comb. rest. along with Cyclosternum macropus Ausserer, 1875, Schizopelma sorkini Smith, 1995, and Lasiodora gutzkei Reichling, 1997, transferred from Lasiodora Koch, 1850 combs. nov. Hapalopus nigriventris (Mello-Leitão, 1939) is redescribed. Lasiodora tetricus (S

The trapdoor spider genus Tigidia Simon, 1892 is distributed in Madagascar, Mauritius, and India, with eleven species, of which the male of only a single species, Tigidia typica (Strand, 1907), is known. Discovery of a male specimen from Western Ghats of Maharashtra allows us to describe a new species and also gives us the opportunity to illustrate another male of the genus for the first time.

A new species, Allochernes fimusensis n. sp., collected from cattle dung (a rare habitat for the genus), is described.

The distribution of lateral eyes in arachnids and their relatives (Chelicerata) is reviewed, including novel data for selected taxa. Particular focus was given to camel spiders (Solifugae) and whip scorpions (Thelyphonida), for which there are conflicting reports about their eye morphology in the literature, and to the condition in some fossil scorpions (Scorpiones) and some extinct trigonotarbid arachnids (Trigonotarbida), which have lateral eyes with c. 30 or up to 15 individual lenses, respectively. Arachnid outgroups like horseshoe crabs (Xiphosura) and sea scorpions (Eurypterida) have compound lateral eyes, but the hypothesis that reduction of these eyes to five lenses or fewer is a synapomorphy of Arachnida can be rejected. Fossil data indicate, instead, that the arachnid lateral eyes were also originally (semi-) compound, and that reduction to only a handful of lenses must be a homoplastic character state. Note that camel spiders retain vestigial lateral eyes, while fossil ricinuleids had a pair of lateral eyes not seen in the living representatives. Among the Pantetrapulmonata group, i.e. spiders and their closest relatives, there is a clear trend towards the lateral eyes consolidating into triads of three lenses. A number of earlybranching spider families (e.g. Hypochilidae, Atypidae, but interestingly not Liphistiidae) retain clear evidence of triads. Whip scorpions unequivocally have two additional minor lenses, documented here photographically, while at least some Devonian trigonotarbids show more than five lateral eye lenses: implying a compound eye in the process of reducing to a simple lens-based system. Most arachnids rely more on non-visual sensory inputs, which may explain why reduction of the lateral eyes appears to be a common evolutionary trend.