A new genus and two new species of the millipede family Chelodesmidae from Bahia state, northeastern Brazil, including a likely troglobiont (Diplopoda, Polydesmida).

A new genus and two new species of Chelodesmidae are described from two caves of the Joo Rodrigues river system in Bahia state, northeastern Brazil: Strongylosomides troglobius sp. nov. and Rotundotergum elevatum gen. nov., sp. nov. The former species differs from congeners primarily by the gonopods showing the prefemoral process strongly fused caudally along its basal half to the acropodite and, in showing such troglomorphic traits as a nearly unpigmented and fragile body with thin tegument, it seems the first troglobiont to be documented in the genus. Moreover, this new species seems to be so remarkably similar to Leptodesmus stercoriarius Schubart, 1956, from Minas Gerais state, that the following new combination is warranted: Strongylosomides stercoriarius (Schubart, 1956), comb. nov. ex Leptodesmus de Saussure, 1859. The new genus, Rotundotergum gen. nov., seems to be especially similar to Eucampesmella Schubart, 1955, but differs clearly by the absence of a secondary process on the gonopodal prefemoral process, coupled with the latter being unusually long and strongly separated from the acropodite. The type species R. elevatum sp. nov., being partly clearly pigmented, seems to be only troglophilic. The region generally supports a typical dry tropical climate, whereas the caves represent sites with high humidity, this being essential for the survival of these and other species. However, these habitats remain unprotected by Brazilian law, while the Joo Rodrigues River system is threatened by irrigation projects, potential limestone exploitation, asphalt and road widening or construction that pass across the system and can collapse the rock, and pollution of the subterranean drainage. We hope that the new species described here could help us protect their type localities and the Joo Rodrigues River system as a whole.

Two new species of the millipede family Trichopolydesmidae from Bahia state, northeastern Brazil, including a remarkable threatened troglobiont (Diplopoda, Polydesmida).

Phaneromerium troglopterygotum sp. nov. and Moojenodesmus schubarti sp. nov. are described from Bahia state, northeastern Brazil. The former species is a remarkable troglobiont relict endemic to a single limestone cave from the Serra do Ramalho karst area; it shows some clear-cut troglomorphic traits, and particular biology and ecology. The latter species occurs close to limestone outcrops of the Serra do Iuiu karst area. Both regions generally support a typical dry tropical climate, but the cave and outcrop habitats represent sites with high humidity, this being essential for the survival of these and other species.

Ctenus igatu sp. nov. (Araneae: Ctenidae): a new subterranean spider from Brazil with an analysis of troglomorphic traits

In this work we describe Ctenus igatu sp. nov., the first ctenid spider from South America with conspicuous troglomorphic traits, including elongated appendages, reduction of eyes, and body depigmentation. The new species is only known to occur in a unique sandstone cave from the state of Bahia, north-eastern Brazil. The morphology of the genitalia suggests that Ctenus igatu sp. nov. is closely related to Ctenus fasciatus Mello-Leitão, 1943, a facultative subterranean species from caves in the state of São Paulo, south-eastern Brazil. In addition, we compared morphological traits possibly related to the isolation in subterranean habitats, such as ratios between carapace length vs. leg IV length and eye diameters vs. carapace length, of 19 species of Ctenus (17 epigean species, C. fasciatus and the new troglobitic species described herein). Our analysis showed that both C. fasciatus as C. igatu sp. nov. have morphological troglomorphisms, with C. igatu sp. nov. showing marked specializations to subterranean life.

Fundamental research questions in subterranean biology.

Five decades ago, a landmark paper in Science titled The Cave Environment heralded caves as ideal natural experimental laboratories in which to develop and address general questions in geology, ecology, biogeography, and evolutionary biology. Although the 'caves as laboratory' paradigm has since been advocated by subterranean biologists, there are few examples of studies that successfully translated their results into general principles. The contemporary era of big data, modelling tools, and revolutionary advances in genetics and (meta)genomics provides an opportunity to revisit unresolved questions and challenges, as well as examine promising new avenues of research in subterranean biology. Accordingly, we have developed a roadmap to guide future research endeavours in subterranean biology by adapting a well-established methodology of 'horizon scanning' to identify the highest priority research questions across six subject areas. Based on the expert opinion of 30 scientists from around the globe with complementary expertise and of different academic ages, we assembled an initial list of 258 fundamental questions concentrating on macroecology and microbial ecology, adaptation, evolution, and conservation. Subsequently, through online surveys, 130 subterranean biologists with various backgrounds assisted us in reducing our list to 50 top-priority questions. These research questions are broad in scope and ready to be addressed in the next decade. We believe this exercise will stimulate research towards a deeper understanding of subterranean biology and foster hypothesis-driven studies likely to resonate broadly from the traditional boundaries of this field.

Four new troglophilic species of Loxosceles Heinecken & Lowe, 1832: contributions to the knowledge of recluse spiders from Brazilian caves (Araneae, Sicariidae).

Four new species of recluse spiders from Brazilian caves are described with both males and females. Loxoscelesericsoni Bertani, von Schimonsky & Gallão, sp. n. and L.karstica Bertani, von Schimonsky & Gallão, sp. n. both occur in caves in the Peruaçu region, located in the northern area of the state of Minas Gerais; L.karstica sp. n. is additionally found in the Serra do Ramalho karst area, located in the southwestern region of the state of Bahia. These two species belong to the gaucho group. Loxoscelescarinhanha Bertani, von Schimonsky & Gallão, sp. n. and L.cardosoi Bertani, von Schimonsky & Gallão, sp. n. occur exclusively in caves of the Serra do Ramalho karst area and belong to the rufescens/amazonica species group. The discovery of two additional and highly distinct species in the rufescens/amazonica group (L.carinhanha sp. n. and L.cardosoi sp. n.) increases the debate on the origin, evolution, and geographical distribution of this widely distributed group of recluse spiders in the New and Old World. The presence of three species (L.ericsoni sp. n., L.carinhanha sp. n., and L.cardosoi sp. n.) with marked differences in morphological characters in a relatively small area indicates that the region seems to be an important center for Loxosceles diversity, which remains poorly studied.

Four new troglophilic species of Loxosceles Heinecken & Lowe, 1832: contributions to the knowledge of recluse spiders from Brazilian caves (Araneae, Sicariidae)

Four new species of recluse spiders from Brazilian caves are described with both males and females. Loxosceles ericsoni Bertani, von Schimonsky & Gallao, sp. n. and L. karstica Bertani, von Schimonsky & Gallao, sp. n. both occur in caves in the Peruacu region, located in the northern area of the state of Minas Gerais; L. karstica sp. n. is additionally found in the Serra do Ramalho karst area, located in the southwestern region of the state of Bahia. These two species belong to the gaucho group. Loxosceles carinhanha Bertani, von Schimonsky & Gallao, sp. n. and L. cardosoi Bertani, von Schimonsky & Gallao, sp. n. occur exclusively in caves of the Serra do Ramalho karst area and belong to the rufescensl amazonica species group. The discovery of two additional and highly distinct species in the rufescensl amazonica group (L. carinhanha sp. n. and L. cardosoi sp. n.) increases the debate on the origin, evolution, and geographical distribution of this widely distributed group of recluse spiders in the New and Old World. The presence of three species (L ericsoni sp. n., L. carinhanha sp. n., and L. cardosoi sp. n.) with marked differences in morphological characters in a relatively small area indicates that the region seems to be an important center for Loxosceles diversity, which remains poorly studied.

Four new troglophilic species of Loxosceles Heinecken & Lowe, 1832: contributions to the knowledge of recluse spiders from Brazilian caves (Araneae, Sicariidae)

Four new species of recluse spiders from Brazilian caves are described with both males and females. Loxosceles ericsoni Bertani, von Schimonsky & Gallao, sp. n. and L. karstica Bertani, von Schimonsky & Gallao, sp. n. both occur in caves in the Peruacu region, located in the northern area of the state of Minas Gerais; L. karstica sp. n. is additionally found in the Serra do Ramalho karst area, located in the southwestern region of the state of Bahia. These two species belong to the gaucho group. Loxosceles carinhanha Bertani, von Schimonsky & Gallao, sp. n. and L. cardosoi Bertani, von Schimonsky & Gallao, sp. n. occur exclusively in caves of the Serra do Ramalho karst area and belong to the rufescensl amazonica species group. The discovery of two additional and highly distinct species in the rufescensl amazonica group (L. carinhanha sp. n. and L. cardosoi sp. n.) increases the debate on the origin, evolution, and geographical distribution of this widely distributed group of recluse spiders in the New and Old World. The presence of three species (L ericsoni sp. n., L. carinhanha sp. n., and L. cardosoi sp. n.) with marked differences in morphological characters in a relatively small area indicates that the region seems to be an important center for Loxosceles diversity, which remains poorly studied.

Light from dark: A relictual troglobite reveals a broader ancestral distribution for kimulid harvestmen (Opiliones: Laniatores: Kimulidae) in South America.

A new troglobitic harvestman, Relictopiolus galadriel gen. nov et sp. nov., is described from Olhos d'Água cave, Itacarambi, Minas Gerais State, Brazil. Morphological characters, including male genitalia and exomorphology, suggest that this species belongs to the family Kimulidae, and it appears to share the greatest similarities with Tegipiolus pachypus. Bayesian inference analyses of a molecular dataset strongly support the inclusion of this species in Kimulidae and confirm the hypothesized sister-group relationship between R. galadriel and T. pachypus. A time calibrated phylogeny indicates that these sister-taxa diverged from a common ancestor approximately 40 Mya, during the Paleogene. The current range of Kimulidae illustrates a remarkable disjunct distribution, and leads us to hypothesize that the ancestral distribution of Kimulidae was once much more widespread across eastern Brazil. This may be attributed to the Eocene radiation associated with the warming (and humidifying) events in the Cenozoic when the best conditions for evergreen tropical vegetation in South America were established and followed by the extinction of kimulid epigean populations together with the retraction of rain forests during the Oligocene to Miocene cooling. The discovery of this relictual troglobite indicates that the Olhos d'Água cave was a stable refugium for this ancient lineage of kimulids and acted as a "museum" of biodiversity. Our findings, considered collectively with the diverse troglofauna of the Olhos d'Água cave, highlight it as one of the most important hotspots of troglobite diversity and endemism in the Neotropics. Given the ecological stresses on this habitat, the cavernicolous fauna are at risk of extinction and we emphasize the urgent need for appropriate conservation actions. Finally, we propose the transfer of Acanthominua, Euminua, Euminuoides and Pseudominua from Kimulidae to Zalmoxidae, resulting in two new synonymies and 13 new combinations.