A new troglomorphic species of Larca (Pseudoscorpiones, Larcidae) from Colorado.

A new species of Larca is described from dry habitats in a cave in central Colorado. Like other cave-dwelling species of Larca, the new species Larcabouldericasp. nov., shows relatively modest morphological adaptations, such as pale colouration and slightly elongated appendages, compared with their epigean counterparts. This species is the sixth cave-dwelling species of Larca described from North America and, like other cave-dwelling Larca in North America and Europe, tends to be distributed in more southerly regions.

Four new species of cave-adapted pseudoscorpions (Pseudoscorpiones, Pseudotyrannochthoniidae) from Guizhou, China.

Four new troglomorphic pseudotyrannochthoniid pseudoscorpion species collected from karst caves in Guizhou Province are described with detailed diagnoses and illustrations: Allochthoniusbainiensis sp. nov. from Liangfeng Cave (Xishui County), Allochthoniuspandus sp. nov. from Daozuo Cave (Xishui County), Allochthoniusxinqiaoensis sp. nov. from Sanjie Cave (Fenggang County), and Spelaeochthoniuswulibeiensis sp. nov. from Wulibei Cave (Weining County). Spelaeochthoniuswulibeiensis sp. nov. represents the first record of the genus in China. The diagnostic features of these four new cave-adapted (troglomorphic) species are presented and discussed, as well as compared with closely related species. The data on their distribution, habitat and ecology of the species are also given.

Worldwide distribution of cave-dwelling Chelodesmidae (Diplopoda, Polydesmida)

Chelodesmidae is one of the most species rich families within the Myriapoda. However, little is known regarding their association with caves. We provide a list of all Chelodesmidae taxa reported from caves, map their worldwide distribution, and discuss the troglomorphic features of the group. A total of 25 species and subspecies from 20 genera and 2 subfamilies have been recorded from 59 caves and cave systems in 11 countries. These numbers represent a surprisingly modest proportion (~3%) of the approximately 800 described species in the family. Records of cave-dwelling chelodesmids appear to be geographically biased with most taxa reported from the Neotropics, likely due to the greater diversity of the group in the region. The lack of published records from the Afrotropics can undoubtedly be attributed to low sampling efforts. In addition, many studies focusing on cave invertebrates, especially in the tropics, often fail to identify chelodesmid taxa to the species level, thus precluding their inclusion on checklists. The majority of the Chelodesmidae reported from caves do not display obvious adaptations to a subterranean lifestyle and are not troglomorphic. The five troglobitic taxa indicated in this study may represent relictual lineages suggesting that few, if any, radiations of chelodesmids within caves have occurred in the past. Increased efforts are needed to bridge the gap between our current understanding and the true diversity of the group in these fragile and threatened habitats, which is necessary to allow policy makers to prioritize appropriate and effective conservation efforts, including the protection of environments severely impacted by human activities.

Cuticular Structures in Micropterous Crickets (Orthoptera, Gryllidae, Petaloptilini, Gryllomorphini).

Orthoptera is a very diverse group that has colonized practically all terrestrial ecosystems on the planet. They have adapted to live in the endogenous environment as well as in caves so that some species exhibit troglomorphic characteristics. This group has been extensively studied due to its economic and social importance; however, many basic morphological and biological questions remain to be solved. In this study, a comparative morphological study by scanning electron microscopy of different structures of eight species of micropteran crickets of the tribes Gryllomorphini and Petaloptilini, whose tegmina had lost their flight and song functionality was carried out. Special emphasis was placed on the tegmina and their possible relationship to reproductive functions. In addition, to assess troglomorphism in the genus Petaloptila, the biometric parameters of six other species have been considered. Actualization of the lifestyle of the studied species has also been carried out. The results show structures not previously described in this group (gland openings, setae, pores, or group of campaniform sensilla). Structures not previously described in this group have been detected, and tegmina (glandular openings and devoured tegmina) seem to confer a role in reproduction. Troglomorphisms are only observed in species of the subgenus Zapetaloptila. Statistically, significant differences have been found in characters such as cephalic elongation, ocular reduction, greater length of appendages, and depigmentation.

Genomic Analysis of the Only Blind Cichlid Reveals Extensive Inactivation in Eye and Pigment Formation Genes.

Trait loss represents an intriguing evolutionary problem, particularly when it occurs across independent lineages. Fishes in light-poor environments often evolve "troglomorphic" traits, including reduction or loss of both pigment and eyes. Here, we investigate the genomic basis of trait loss in a blind and depigmented African cichlid, Lamprologus lethops, and explore evolutionary forces (selection and drift) that may have contributed to these losses. This species, the only known blind cichlid, is endemic to the lower Congo River. Available evidence suggests that it inhabits deep, low-light habitats. Using genome sequencing, we show that genes related to eye formation and pigmentation, as well as other traits associated with troglomorphism, accumulated inactivating mutations rapidly after speciation. A number of the genes affected in L. lethops are also implicated in troglomorphic phenotypes in Mexican cavefish (Astyanax mexicanus) and other species. Analysis of heterozygosity patterns across the genome indicates that L. lethops underwent a significant population bottleneck roughly 1 Ma, after which effective population sizes remained low. Branch-length tests on a subset of genes with inactivating mutations show little evidence of directional selection; however, low overall heterozygosity may reduce statistical power to detect such signals. Overall, genome-wide patterns suggest that accelerated genetic drift from a severe bottleneck, perhaps aided by directional selection for the loss of physiologically expensive traits, caused inactivating mutations to fix rapidly in this species.

Comparative transcriptomics reveals the molecular genetic basis of pigmentation loss in Sinocyclocheilus cavefishes.

Cave-dwelling animals evolve distinct troglomorphic traits, such as loss of eyes, skin pigmentation, and augmentation of senses following long-term adaptation to perpetual darkness. However, the molecular genetic mechanisms underlying these phenotypic variations remain unclear. In this study, we conducted comparative histology and comparative transcriptomics study of the skin of eight Sinocyclocheilus species (Cypriniformes: Cyprinidae) that included surface- and cave-dwelling species. We analyzed four surface and four cavefish species by using next-generation sequencing, and a total of 802,798,907 clean reads were generated and assembled into 505,495,009 transcripts, which contributed to 1,037,334 unigenes. Bioinformatic comparisons revealed 10,629 and 6,442 significantly differentially expressed unigenes between four different surface-cave fish groups. Further, tens of differentially expressed genes (DEGs) potentially related to skin pigmentation were identified. Most of these DEGs (including GNAQ, PKA, NRAS, and p38) are downregulated in cavefish species. They are involved in key signaling pathways of pigment synthesis, such as the melanogenesis, Wnt, and MAPK pathways. This trend of downregulation was confirmed through qPCR experiments. This study will deepen our understanding of the formation of troglomorphic traits in cavefishes.

Genetic analysis reveals candidate genes for activity QTL in the blind Mexican tetra, Astyanax mexicanus.

Animal models provide useful tools for exploring the genetic basis of morphological, physiological and behavioral phenotypes. Cave-adapted species are particularly powerful models for a broad array of phenotypic changes with evolutionary, developmental and clinical relevance. Here, we explored the genetic underpinnings of previously characterized differences in locomotor activity patterns between the surface-dwelling and Pachón cave-dwelling populations of Astyanax mexicanus. We identified multiple novel QTL underlying patterns in overall levels of activity (velocity), as well as spatial tank use (time spent near the top or bottom of the tank). Further, we demonstrated that different regions of the genome mediate distinct patterns in velocity and tank usage. We interrogated eight genomic intervals underlying these activity QTL distributed across six linkage groups. In addition, we employed transcriptomic data and draft genomic resources to generate and evaluate a list of 36 potential candidate genes. Interestingly, our data support the candidacy of a number of genes, but do not suggest that differences in the patterns of behavior observed here are the result of alterations to certain candidate genes described in other species (e.g., teleost multiple tissue opsins, melanopsins or members of the core circadian clockwork). This study expands our knowledge of the genetic architecture underlying activity differences in surface and cavefish. Future studies will help define the role of specific genes in shaping complex behavioral phenotypes in Astyanax and other vertebrate taxa.

Two new troglobiont Pygmarrhopalites species of the principalis group (Collembola: Arrhopalitidae) from the West Caucasus.

Springtails of the principalis-group of the genus Pygmarrhopalites from the W Caucasian caves in Abkhazia are described: Pygmarrhopalites dbari sp. nov. from Psyrtskha Cave in Novy Afon and Pygmarrhopalites kovali sp. nov. from caves of Tsebelda Karst Massif. They differ from epigean relatives mainly by troglomorphies: reduced pigmentation, elongated appendages and modified foot complex. These new species as well as a great portion of endemic Caucasian speleofauna have highly restricted distribution and require protection. A new record of Arrhopalites abchasicus Vargovitsh, 2013 in Novoafonskaya Cave is added.

Trichomycterus uisae: a new species of hypogean catfish (Siluriformes: Trichomycteridae) from the northeastern Andean Cordillera of Colombia

Trichomycterus uisae, a new species of hypogean catfish, is described from Cueva El Misterio located in the upper Sogamoso river basin of the Departamento de Santander in the northeastern portion of the Andean range of Colombia. The new species has a characteristic dark bluish-gray band from the head to the origin of the dorsal fin, five to nine opercular odontodes, and the anterior and posterior fontanels separated but connected by a narrow channel. A comparative analysis with epigean species from Colombia and troglobitic Trichomycterus from South America is presented.

Trichomycterus uisae, uma nova espécie de bagre hipógeo, é descrita da Caverna El Misterio, localizada na parte alta da bacia do rio Sogamoso, no Departamento de Santander na parte nordeste dos Andes da Colômbia. A nova espécie tem uma banda cinza-azulada caraterística que vai desde a cabeça até a origem da nadadeira dorsal; cinco a nove odontódeos operculares; e fontanelas anterior e posterior separadas, mas conectadas por um canal estreito. Uma análise comparativa com espécies epígeas da Colômbia e Trichomycterus troglóbios da América do Sul é apresentada.