The spider genus Dysdera Latreille is an excellent model for the study of the evolution of cave life: ten species are known to exist exclusively in the subterranean environment of the Canary Islands, where the genus has undergone local diversification. In the present paper, two new troglobitic species (Dysdera madai, sp. nov. and D. sibyllina, sp. nov.) and the previously unknown sex of five additional species are described and illustrated: the males of D. gollumi Ribera & Arnedo, 1994, D. hernandezi Arnedo & Ribera, 1999 and D. labradaensis Wunderlich, 1991; and the females of D. andamanae Arnedo & Ribera, 1997 and D. gibbifera Wunderlich, 1991. The first direct evidence of troglobitic members of Dysdera in micro- and mesocaverns are reported. The evolution of cave life as hypothesised following a combined morphological and molecular phylogeny is investigated. Troglobitic Canarian Dysdera species have colonised the underground on eight independent occasions. The Dysderidae groundplan represents a preadaptation to cave life and has facilitated the colonisation of caves. Canarian members of Dysdera have a predominantly parapatric mode of speciation, although postspeciation changes in distribution may have obscured allopatric processes. Eye regression and, to a lesser extent, larger body size and appendage elongation characterise troglobitic species. The different levels of troglobiomorphism are interpreted as local adaptations to heterogeneous subterranean conditions. The high levels of sympatry among troglobites are explained by trophic segregation and changes in prey capture strategy were involved in the single identified case of subterranean speciation in the group.

Fifteen species of the darkling beetle genus Pimelia (Tenebrionidae: Coleoptera) have been sequenced for a 365 b.p. portion of the mitochondrial Cytochrome Oxidase I gene. Thirteen of these are endemic species inhabiting the Canarian archipelago in the Atlantic and the other two are continental conspecifics. This data set has been phylogenetically analysed by maximum parsimony and distance approaches and the resulting trees used to deduce sequential interisland colonization. This suggests patterns compatible with the geological dating of the islands, but with increasing uncertainty when older events are considered. A colonization sequence from Fuerteventura to Tenerife followed by Tenerife to Gran Canaria and La Gomera, and from the latter to La Palma and then to El Hierro is proposed for the genus. A relatively recent secondary colonization from Gran Canaria to Gomera is deduced.

Within the soil matrix and underlying rock, cracks and fissures and other air-filled spaces between rocks, sometimes called the milieu souterrain superficiel (MSS), are present in a variety of geological contexts. We examined year-long hourly temperature profiles at sites in lava in the Canary Islands and limestone in Slovenia. All sites had species that show morphological adaptations usually associated with cave-dwelling organisms, including elongated appendages and reduced eyes and pigment. MSS sites were studied at depths between 10 and 70 cm and showed strong seasonality, and most had a discernible diurnal cycle as well. The most striking difference from surface habitats was that the temperature extremes were much less pronounced in MSS sites. Temperature variability was not correlated with troglobiotic species richness. The presence of species with similar morphologies to those found in caves indicates that selective pressures are similar in cave and shallow subterranean habitats.