The dark side of pseudoscorpion diversity: The German Barcode of Life campaign reveals high levels of undocumented diversity in European false scorpions

Of sea, rivers and symbiosis: Diversity, systematics, biogeography and evolution of the deeply diverging florideophycean order Hildenbrandiales (Rhodophyta)

The Hildenbrandiales, a typically saxicolous red algal order, is an early diverging florideophycean group with global significance in marine and freshwater ecosystems across diverse temperature zones. To comprehensively elucidate the diversity, phylogeny, biogeography, and evolution of this order, we conducted a thorough re-examination employing molecular data derived from nearly 700 specimens. Employing a species delimitation method, we identified Evolutionary Species Units (ESUs) within the Hildenbrandiales aiming to enhance our understanding of species diversity and generate the first time-calibrated tree and ancestral area reconstruction for this order. Mitochondrial cox1 and chloroplast rbcL markers were used to infer species boundaries, and subsequent phylogenetic reconstructions involved concatenated sequences of cox1, rbcL, and 18S rDNA. Time calibration of the resulting phylogenetic tree used a fossil record from a Triassic purportedly freshwater Hildenbrandia species and three secondary time points from the literature. Our species delimitation analysis revealed an astounding 97 distinct ESUs, quintupling the known diversity within this order. Our time-calibration analysis placed the origin of Hildenbrandiales (crown age) in the Ediacaran period, with freshwater species emerging as a monophyletic group during the later Permian to early Triassic. Phylogenetic reconstructions identified seven major clades, experiencing early diversification during the Silurian to Carboniferous period. Two major evolutionary events-colonization of freshwater habitats and obligate systemic symbiosis with a marine fungus-marked this order, leading to significant morphological alterations without a commensurate increase in species diversification. Despite the remarkable newly discovered diversity, the extant taxon diversity appears relatively constrained when viewed against an evolutionary timeline spanning over 800 million years. This limitation may stem from restricted geographic sampling or the prevalence of asexual reproduction. However, species richness estimation and rarefaction analyses suggest a substantially larger diversity yet to be uncovered-potentially four times greater. These findings drastically reshape our understanding of the deeply diverging florideophycean order Hildenbrandiales species diversity, and contribute valuable insights into this order's evolutionary history and ecological adaptations. Supported by phylogenetic, ecological and morphological evidence, we established the genus Riverina gen. nov. to accommodate freshwater species of Hildenbrandiales, which form a monophyletic clade in our analyses. This marks the first step toward refining the taxonomy of the Hildenbrandiales, an order demanding thorough revisions, notably with the creation of several genera to address the polyphyletic status of Hildenbrandia. However, the limited diagnostic features pose a challenge, necessitating a fresh approach to defining genera. A potential solution lies in embracing a molecular systematic perspective, which can offer precise delineations of taxonomic boundaries.

Machine learning approaches delimit cryptic taxa in a previously intractable species complex

Cryptic species are not diagnosable via morphological criteria, but can be detected through analysis of DNA sequences. A number of methods have been developed for identifying species based on genetic data; however, these methods are prone to over-splitting taxa with extreme population structure, such as dispersal-limited organisms. Machine learning methodologies have the potential to overcome this challenge. Here, we apply such approaches, using a large dataset generated through hybrid target enrichment of ultraconserved elements (UCEs). Our study taxon is the Aoraki denticulata species complex, a lineage of extremely low-dispersal arachnids endemic to the South Island of Aotearoa New Zealand. This group of mite harvesters has been the subject of previous species delimitation studies using smaller datasets generated through Sanger sequencing and analytical approaches that rely on multispecies coalescent models and barcoding gap discovery. Those analyses yielded a number of putative cryptic species that seems unrealistic and extreme, based on what we know about species' geographic ranges and genetic diversity in non-cryptic mite harvesters. We find that machine learning approaches, on the other hand, identify cryptic species with geographic ranges that are similar to those seen in other morphologically diagnosable mite harvesters in Aotearoa New Zealand's South Island. We performed both unsupervised and supervised machine learning analyses, the latter with training data drawn either from animals broadly (vagile and non-vagile) or from a custom training dataset from dispersal-limited harvesters. We conclude that applying machine learning approaches to the analysis of UCE-derived genetic data is an effective method for delimiting species in complexes of low-vagility cryptic species, and that the incorporation of training data from biologically relevant analogues can be critically informative.

Molecular diversity of Diplura in southern High Appalachian leaf litter

The fauna of Diplura, the two-pronged bristletails (Hexapoda), of the southern Appalachians has received little focused systematic attention. Existing literature suggests the fauna to comprise around a dozen species. Based on a broader DNA barcode-based survey of high elevation litter arthropods in the region, we suggest the fauna to be much richer, with automated species delimitation methods hypothesising as many as 35 species, most highly restricted to single or closely proximate localities. Such a result should not be very surprising for such small, flightless arthropods, although it remains to be seen if other markers or morphology support such high diversity. The region still remains sparsely sampled for these more cryptic elements of the arthropod fauna and much larger numbers of species undoubtedly remain to be discovered.

More Than 200 Years Later: Gluvia brunnea sp. nov. (Solifugae, Daesiidae), a Second Species of Camel Spider from the Iberian Peninsula

We present the description of a new species of Solifugae from the Iberian Peninsula, Gluvia brunnea sp. nov., which has been found so far in southeast Spain. The morphological description is accompanied by molecular and multiple factor analyses, jointly giving full support to the specific status of the taxon. Finally, we discuss the intraspecific variability of both species, G. dorsalis and G. brunnea sp. nov., and the recent history of the genus. We also discuss the usefulness of multiple factor analysis for quantitatively separating species, and we stress that some specimens of this new species were found in Mesovoid Shallow Substratum stations, representing the very first time that Solifugae have been captured in this type of trap.

Molecular diversity of Pseudoscorpiones in southern High Appalachian leaf litter

The Pseudoscorpiones fauna of North America is diverse, but in regions like the southern Appalachian Mountains, they are still poorly documented with respect to their species diversity, distributions and ecology. Several families have been reported from these mountains and neighbouring areas. Here we analyse barcoding data of 136 specimens collected in leaf litter, most of them from high-elevation coniferous forest. We used ASAP as a species delimitation method to obtain an estimation of the number of species present in the region. For this and based on interspecific genetic distance values previously reported in Pseudoscorpions, we considered three different genetic Kimura two-parameter distance thresholds (3%/5%/8%), to produce more or less conservative estimates. These distance thresholds resulted in 64/47/27 distinct potential species representing the families Chthoniidae (33/22/12 species) and Neobisiidae (31/25/15) and at least six different genera within them. The diversity pattern seems to be affected by the Asheville Depression, a major biogeographic barrier in this area, with a higher diversity to the west of this geographic feature, particularly within the family Neobisiidae. The absence of representatives from other families amongst our studied samples may be explained by differences in their ecological requirements and occupation of different microhabitats.

The troglomorphic pseudoscorpions of the genus Neobisium from Corsica, Sardinia and mainland Italy, with description of new species (Pseudoscorpiones: Neobisiidae)

A taxonomic revision and a key to the pseudoscorpion species of Neobisium Chamberlin, 1930so far attributed to the subgenus Ommatoblothrus Beier, 1956from Corsica, Sardinia and mainland Italy are provided. The taxonomic status of the subgenera of Neobisium Chamberlin, 1930 is evaluated and the following new synonymies are proposed: Ommatoblothrus Beier, 1956 is a junior subjective synonym of Neobisium Chamberlin, 1930 (n. syn.), Heoblothrus Browning, 1965 is a junior subjective synonym of Neobisium Chamberlin, 1930 (n. syn.), Pennobisium uri 1988 is a junior subjective synonym of Neobisium Chamberlin, 1930 (n. syn.). The following new species are described: Neobisium (Neobisium) corsicum n. sp. (, loc. typ.: Corsica, Corte, Grotte de Valletto), Neobisium (N.) leolatellai n. sp. (, loc. typ.: Latium, Bassiano, Grotta della Cava 384 La/LT), Neobisium (N.) magrinii n. sp. (, loc. typ.: Latium, Coreno Ausonio, Grotta lArnale 871 La/FR), Neobisium (N.) petruzzielloi n. sp. (, loc. typ.: Campania, Avella, Grotta degli Sportiglioni 184 Cp/AV) and Neobisium (N.) vignai n. sp. (, loc. typ.: Latium, Amaseno, Grotta degli Ulivi 474 La/FR). The specimens of five populations from as many caves of the Lepini Mountains are provisionally attributed to Neobisium (N.) sp. aff. patrizii Beier, 1953, and the following new synonymy is proposed: Neobisium patrizii romanum Mahnert, 1980 is a junior subjective synonym of Neobisium patrizii patrizii Beier, 1953 (n. syn.).

Phoretic behavior of the pseudoscorpion Megachernes ryugadensis on the Japanese wood mouse Apodemus speciosus

Phoresy is a passive transportation behavior where one organism (phoront) disperses to a new location by attaching to another organism. Pseudoscorpions are arthropod predators that mainly live in soil, subterranean habitats, and under tree bark. Some species also live in animal nests and engage in phoresy on small mammals, suggesting close associations with these animals. However, the relationship between phoretic pseudoscorpions and hosts as well as the ecological significance of phoresy remain largely unexplored. Here, to understand the function of phoresy of Megachernes ryugadensis, phoretic on small mammals, their phoretic behavior was investigated in a deciduous forest in northern Japan; individual-level dynamics of phoresy were examined by over 3-year mark-recapture surveys that concurrently marked the host and phoront; and host characteristics, such as sex and age class, were analyzed based on a 2-year small mammal trapping survey. The primary host species was the abundant Japanese wood mouse Apodemus speciosus. Out of 132 pseudoscorpions marked, 5 were recaptured approximately 1 month later. No pseudoscorpions were recaptured within the same census period (3-4 days) when they were marked, indicating that phoresy events last less than one night, and pseudoscorpions are unlikely to engage in phoresy again within a few weeks of their initial engagement. Furthermore, analysis of host characteristics revealed a tendency for female mice and adult individuals to have a higher probability of being hosts compared with males and subadults, respectively. Based on the findings in this and previous studies, the function of phoresy in this species is discussed.

The systematics of the pseudoscorpion genus Indohya (Pseudoscorpiones: Hyidae) in Australia

The pseudoscorpion genus Indohya Beier, 1974 is known to occur in three Gondwanan fragments around the Indian Oceansouthern India, Madagascar and north-western Australiasuggesting that the genus had evolved prior to the breakup of Gondwana and was present on each landmass as they rifted apart during the Mesozoic. The Australian fauna is the most diverse, with nine species previously described from Cape Range and the Kimberley region of north-western Australia. The present study documents the genus Indohya in Australia using a combination of morphology and DNA sequence data. We found a total of 36 species, including 27 new species. The majority of the Pilbara fauna consist of blind troglobites collected from subterranean ecosystems, with an additional three eyed species from epigean habitats. The new species consist of one from Cape Range (I. anastomosa Harvey & Burger, n. sp.), 21 from the Pilbara (I. adlardi Harvey & Burger, n. sp., I. alexanderi Harvey & Burger, n. sp., I. aphana Harvey & Burger, n. sp., I. aquila Harvey & Burger, n. sp., I. arcana Harvey & Burger, n. sp., I. arnoldstrongi Harvey & Burger, n. sp., I. boltoni Harvey & Burger, n. sp., I. cardo Harvey & Burger, n. sp., I. catherineae Harvey & Burger, n. sp., I. cockingi Harvey & Burger, n. sp., I. cribbi Harvey & Burger, n. sp., I. draconis Harvey & Burger, n. sp., I. furtiva Harvey & Burger, n. sp., I. incomperta Harvey & Burger, n. sp., I. jessicae Harvey & Burger, n. sp., I. lynbeazlyeae Harvey & Burger, n. sp., I. morganstrongi Harvey & Burger, n. sp., I. rixi Harvey & Burger, n. sp., I. sagmata Harvey & Burger, n. sp., I. scanloni Harvey & Burger, n. sp. and I. silenda Harvey & Burger, n. sp.) and five from the Kimberley (I. currani Harvey & Burger, n. sp., I. finitima Harvey & Burger, n. sp., I. julianneae Harvey & Burger, n. sp., I. karenae Harvey & Burger, n. sp. and I. sachsei Harvey & Burger, n. sp.). The study is augmented with sequence data from 29 species of Indohya, including all of the 24 species recorded from the Pilbara and Cape Range, and five of the 12 known Kimberley species. Seven clades recovered during the molecular analysis are only represented by nymphs, but we used COI sequence data to diagnose these species in the absence of adult morphological data.

Integrative Taxonomy Approach Reveals Cryptic Diversity within the Phoretic Pseudoscorpion Genus Lamprochernes (Pseudoscorpiones: Chernetidae)

Pseudoscorpions represent an ancient, but homogeneous group of arachnids. The genus Lamprochernes comprises several morphologically similar species with wide and overlapping distributions. We implemented an integrative approach combining molecular barcoding (cox1), with cytogenetic and morphological analyses in order to assess species boundaries in European Lamprochernes populations. The results suggest ancient origins of Lamprochernes species accompanied by morphological stasis within the genus. Our integrative approach delimited three nominal Lamprochernes species and one cryptic lineage Lamprochernes abditus sp. nov. Despite its Oligocene origin, L. abditus sp. nov. can be distinguished from its closest relative only by molecular and cytogenetic differences, or alternatively, by a complex multivariate morphometric analysis involving other Lamprochernes species. The population structure and common haplotype sharing across geographically distant populations in most Lamprochernes species suggest that a phoretic manner of dispersal is efficient in this group.

Molecular analyses of pseudoscorpions in a subterranean biodiversity hotspot reveal cryptic diversity and microendemism

Nested within the Mediterranean biodiversity hotspot, the Dinaric Karst of the western Balkans is one of the world's most heterogeneous subterranean ecosystems and renowned for its highly diverse and mostly endemic fauna. The evolutionary processes leading to both endemism and diversity remain insufficiently understood, and large-scale analyses on taxa that are abundant in both subterranean and surface habitats remain infrequent. Here, we provide the first comprehensive molecular study on Croatian pseudoscorpions, a lineage of arachnids that is common and diverse in both habitats. Phylogenetic reconstructions using 499 COI sequences derived from 128 morphospecies collected across the Dinaric Karst show that: (i) occurrence in karstic microhabitats boosters speciation and endemism in the most diverse genera Chthonius C.L. Koch, 1843 (37 morphospecies) and Neobisium Chamberlin, 1930 (34 morphospecies), (ii) evidence for ongoing diversification is found in many species and species complexes through low optimal thresholds (OTs) and species delineation analyses, and (iii) landscape features, such as mountain ranges, correlate with patterns of genetic diversity in the diverse genus Neobisium. We present two synonymies: Protoneobisium Ćurčić, 1988 = Neobisium, syn. nov., and Archaeoroncus Ćurčić and Rađa, 2012 = Roncus L. Koch, 1873, syn. nov. Overall, our study suggests that karstic microhabitats promote diversification in soil- and cave-dwelling arthropods at all taxonomic levels, but also provide important refugia for invertebrates in past and present periods of environmental change.

Life barcoded by DNA barcodes

The modern concept of DNA-based barcoding for cataloguing biodiversity was proposed in 2003 by first adopting an approximately 600 bp fragment of the mitochondrial COI gene to compare via nucleotide alignments with known sequences from specimens previously identified by taxonomists. Other standardized regions meeting barcoding criteria then are also evolving as DNA barcodes for fast, reliable and inexpensive assessment of species composition across all forms of life, including animals, plants, fungi, bacteria and other microorganisms. Consequently, global DNA barcoding campaigns have resulted in the formation of many online workbenches and databases, such as BOLD system, as barcode references, and facilitated the development of mini-barcodes and metabarcoding strategies as important extensions of barcode techniques. Here we intend to give an overview of the characteristics and features of these barcode markers and major reference libraries existing for barcoding the planet’s life, as well as to address the limitations and opportunities of DNA barcodes to an increasingly broader community of science and society.

Two New Pseudoscorpion Species of the Coastal Genus Garypus L. Koch, 1873 (Garypidae) and an Updated Checklist of the Pseudoscorpiones of Taiwan

Pseudoscorpions are predatory microarthropods that feed on even smaller animals, such as mites and springtails. While these organisms are generally considered terrestrial and live in the leaf litter or under barks or rocks, some pseudoscorpions live in the intertidal area, including species in the genera Anagarypus, Anchigarypus, and Garypus in the family Garypidae. This study describes two new species of the genus Garypus L. Koch from Southern Taiwan, Garypus wilsoni Lin & Chang sp. nov. and Garypus sanasai Lin, Huang & Chang sp. nov., reviews the pseudoscorpion fauna of Taiwan, and provides an updated checklist of the country. Specimens of the two new species were collected in seashore habitats and their status as new species were supported by both morphology and molecular phylogenetic analysis. Our discovery marks the first new species of pseudoscorpions reported in Taiwan since 1937, as well as the first records of the family Garypidae in Taiwan and of Garypus in East Asia. Moreover, the discovery of these two new species in Taiwan fills the regional distribution gap between Garypus in Thailand and southward and its closely related genus Anchigarypus in South Korea and Japan. The location where Garypus sanasai Lin, Huang & Chang sp. nov. was found also represents the northernmost distribution of the genus Garypus in the West Pacific.