A genus-level taxonomic review of primitively segmented spiders (Mesothelae, Liphistiidae)

Seven new species of the segmented spider genus Liphistius (Mesothelae, Liphistiidae) in Thailand and Myanmar

Seven new species of the primitive segmented spider genus Liphistius are described and assigned to species groups based on characters of the male palp and vulva plate. The bristowei group includes L.dawei Sivayyapram & Warrit, sp. nov. (♂♀) from southeastern Myanmar, L.choosaki Sivayyapram & Warrit, sp. nov. (♀) from northwestern Thailand, and L.lansak Sivayyapram & Warrit, sp. nov. (♀) from western Thailand; the trang group (Complex A) contains L.kaengkhoi Sivayyapram & Warrit, sp. nov. (♂♀), L.hintung Sivayyapram & Warrit, sp. nov. (♂♀), L.buyphradi Sivayyapram & Warrit, sp. nov. (♂♀), and L.champakpheaw Sivayyapram & Warrit, sp. nov. (♂♀) from central Thailand.

Systematic notes on three new Luthela (Mesothelae, Heptathelidae) spiders from China, with their descriptions

Three new segmented trapdoor spider species belonging to the family Heptathelidae Kishida, 1923, i.e., Luthelaasukasp. nov. (♂♀, Sichuan), L.beijingsp. nov. (♂♀, Beijing), and L.kagamisp. nov. (♂♀, Sichuan), are described from China. Their phylogenetic position and relationships within Heptathelidae are tested and assessed using a combination available COI data downloaded from GenBank with new DNA sequences obtained in this study. The results show that the new species form a clade with eight known and one undescribed species of Luthela. High-definition illustrations of the male palps and female genitalia, diagnoses, and DNA barcodes are provided for these three new species, and their distributions are mapped.

Three new species of the primitively segmented spider genus Songthela (Mesothelae, Liphistiidae, Heptathelinae) from Hunan Province, China

Three new species of the primitively segmented spider genus Songthela Ono, 2000 are identified and described from Hunan Province, China, based on morphological characters of males and females: S. anhua Zhang & Xu, sp. nov. (♂♀), S. longhui Zhang & Xu, sp. nov. (♂♀), and S. zhongpo Zhang & Xu, sp. nov. (♂♀). All the new Songthela species belong to the multidentata-group according to male palp and female genital morphology.

Geometric regularity in webs of non-orb-weaving spiders

Geometric regularity of spider webs has been intensively studied in orb-weaving spiders, although it is not exclusive of orb weavers. Here, we document the geometrically regular, repetitive elements in the webs of the non-orb-weaving groups Leptonetidae and Telemidae for the first time. Similar to orb weavers, we found areas with regularly spaced parallel lines in the webs of Calileptoneta helferi, Sulcia sp., and cf. Pinelema sp. Furthermore, we provide a detailed account of the regular webs of Ochyrocera (Ochyroceratidae). The sections of the web with regularly disposed parallel lines are built as U-shaped modules reminiscent of orb webs. It has been suggested that the regularly spaced parallel lines in the webs of Ochyroceratidae and Psilodercidae may be produced in a single sweep of their posterior lateral spinnerets, which have regularly spaced aciniform gland spigots, perhaps involving expansion of the spinnerets. To test this hypothesis, we compared the spacing between parallel lines with the spacing between spigots, searched for expansible membranes in the spinnerets, and examined the junctions of regularly spaced lines. The distance between parallel lines was 10-20 times the distance between spigots, and we found no expansible membranes, and the intersection of parallel lines are cemented, which opposes the single sweep hypothesis. Furthermore, we found cues of viscid silk in the parallel lines of the psilodercid Althepus and broadened piriform gland spigots that may be responsible of its production. Finally, we evaluated the presence or absence of geometrically regular web elements across the spider tree of life. We found reports of regular webs in 31 spider families, including 20 families that are not orb weavers and hypothesize that the two basic aspects of regularity (parallel lines spaced at regular intervals, and radial lines spaced at regular angles) probably appeared many times in the evolution of spiders.

Proteonematalycus wagneri Kethley reveals where the opisthosoma begins in acariform mites

It is generally thought that the anterior border of the opisthosoma of acariform mites is delineated by the disjugal furrow, but there is no evidence to support this other than the superficial appearance of tagmosis in some oribatids. It is proposed herein that the disjugal furrow is an apomorphic feature that does not correspond with any segmental borders. Although the disjugal furrow is absent from Proteonematalycus wagneri Kethley, the visible body segments of this species indicate that this furrow, when present, intersects the metapodosoma. Therefore, the disjugal furrow does not delineate the anterior border of the opisthosoma. Instead, this border is between segments D and E (segments VI and VII for all arachnids). This hypothesis can be accommodated by a new model in which the proterosoma warps upwards relative to the main body axis. This model, which is applicable to all Acariformes, if not all arachnids, explains the following phenomena: 1) the location of the gnathosomal neuromeres within the idiosoma; 2) the relatively posterior position of the paired eyes; 3) the shape of the synganglion; 4) the uneven distribution of legs in most species of acariform mites with elongate bodies.

An integrative approach reveals high species diversity in the primitively segmented spider genus

Accurate species delimitation is crucial for our understanding of evolution, biodiversity and conservation. However, morphology-based species delimitation alone appears to be prone to taxonomic errors and ineffective for taxa with high interspecific morphological homogeneity or intraspecific morphological variations, as is the case for mesothele and mygalomorph spiders. Combined molecular–morphology species delimitation has shown great potential to delimit species boundaries in such ancient lineages. In the present study, molecular and morphological evidence were integrated to delimit species of the primitively segmented spider genus Songthela Ono, 2000. The cytochrome c oxidase subunit I gene (COI) was sequenced for 192 novel specimens belonging to 12 putative morphospecies. The evolutionary relationships within Songthela and the 12-morphospecies hypothesis were tested in two steps – species discovery and species validation – using four single-locus species delimitation approaches. All species delimitation analyses supported the 12-species hypothesis. Phylogenetic analyses yielded three major clades in Songthela, which are consistent with morphology. Accordingly, we assigned 19 known and 11 new species (S. aokoulong, sp. nov., S. bispina, sp. nov., S. dapo, sp. nov., S. huayanxi, sp. nov., S. lianhe, sp. nov., S. lingshang, sp. nov., S. multidentata, sp. nov., S. tianmen, sp. nov., S. unispina, sp. nov., S. xiujian, sp. nov., S. zizhu, sp. nov.) of Songthela to three species-groups: the bispina-group, the multidentata-group and the unispina-group. Another new species, S. zimugang, sp. nov., is not included in any species groups, but forms a sister lineage to the bispina- and unispina-groups. These results elucidate a high species diversity of Songthela in a small area and demonstrate that integrating morphology with COI-based species delimitation is fast and cost-effective in delimiting species boundaries. http://zoobank.org/urn:lsid:zoobank.org:pub:AF0F5B31-AFAF-4861-9844-445AE8678B67

Four new species of the primitively segmented spider genus Songthela (Mesothelae, Liphistiidae) from Chongqing Municipality, China

This paper reports four new species of the primitively segmented spider genus Songthela from Chongqing Municipality, China, based on morphological characters of both males and females: S. jinyun sp. nov., S. longbao sp. nov., S. serriformis sp. nov. and S. wangerbao sp. nov. We also provide the GenBank accession codes of mitochondrial DNA barcode gene, cytochrome c oxidase subunit I (COI), for the holotype of four new species for future identification.  

Contributions to the biodiversity of Vietnam – Results of VIETBIO inventory work and field training in Cuc Phuong National Park

VIETBIO [Innovative approaches to biodiversity discovery and characterisation in Vietnam] is a bilateral German-Vietnamese research and capacity building project focusing on the development and transfer of new methods and technology towards an integrated biodiversity discovery and monitoring system for Vietnam. Dedicated field training and testing of innovative methodologies were undertaken in Cuc Phuong National Park as part and with support of the project, which led to the new biodiversity data and records made available in this article collection.

VIETBIO is a collaboration between the Museum für Naturkunde Berlin – Leibniz Institute for Evolution and Biodiversity Science (MfN), the Botanic Garden and Botanical Museum, Freie Universität Berlin (BGBM) and the Vietnam National Museum of Nature (VNMN), the Institute of Ecology and Biological Resources (IEBR), the Southern Institute of Ecology (SIE), as well as the Institute of Tropical Biology (ITB); all Vietnamese institutions belong to the Vietnam Academy of Science and Technology (VAST).

The article collection "VIETBIO" (https://doi.org/10.3897/bdj.coll.63) reports original results of recent biodiversity recording and survey work undertaken in Cuc Phuong National Park, northern Vietnam, under the framework of the VIETBIO project. The collection consist of this “main” cover paper – characterising the study area, the general project approaches and activities, while also giving an extensive overview on previous studies from this area – followed by individual papers for higher taxa as studied during the project. The main purpose is to make primary biodiversity records openly available, including several new and interesting findings for this biodiversity-rich conservation area. All individual data papers with their respective primary records are expected to provide useful baselines for further taxonomic, phylogenetic, ecological and conservation-related studies on the respective taxa and, thus, will be maintained as separate datasets, including separate GUIDs also for further updating.

New specimens from Mid-Cretaceous Myanmar amber illuminate the phylogenetic placement of Lagonomegopidae (Arachnida: Araneae)

New lagonomegopid spiders are described from Mid-Cretaceous Myanmar (Burmese) amber. Two new genera and species based on single specimens, Scopomegops fax gen. & sp. nov. and Hiatomegops spinalis gen. & sp. nov. are described. Two specimens belonging to Lineaburmops beigeli are further described. Additionally, after re-examining the holotype of Odontomegops titan, a detailed description of its basal ventral abdomen is added here. A phylogenetic analysis was performed to investigate the phylogenetic placement of Lagonomegopidae. A matrix of 79 morphological characters, scored for six lagonomegopid taxa and 26 non-lagonomegopid taxa, was analysed through parsimony and Bayesian phylogenetic inference. Our results recover extant Palpimanoidea as a monophyletic group and partly suggest that Lagonomegopidae is the sister-group to extant Palpimanoidea. The external sexual organs, retrolateral tibial apophysis on the male palp and tracheal spiracle in lagonomegopids are discussed.

Three new species of the primitively segmented spider genus Songthela (Araneae, Mesothelae) from Guizhou Province, China

We diagnose and describe three new species of the primitively segmented spider genus Songthela from Guizhou Province, China, based on morphological characters and molecular data: S.liuisp. nov. (♂♀), S.tianzhusp. nov. (♂♀), and S.yupingsp. nov. (♂♀). We provide the genetic distances within and among the three new species based on the DNA barcode gene, cytochrome c oxidase subunit I (COI) to support our descriptions. We also provide the COI GenBank accession codes for the three new species for future identification.

A new species of Liphistius from Myanmar and description of the actual male of L. birmanicus Thorell, 1897 (Araneae, Mesothelae, Liphistiidae)

Five Liphistius Schiödte, 1849 species of the primitively segmented spider family Liphistiidae are currently known from Myanmar. Here, we described a new species, Liphistius pyinoolwin sp. nov. (♂♀), which was collected from Pyin Oo Lwin, Mandalay Region, Myanmar, diagnosed based on its genital morphology. The specimens (2♂♂, 5♀♀) collected by Walter C. Sedgwick from Pyin Oo Lwin in 1982 were misidentified as L. birmanicus Thorell, 1897 and are treated here as the newly described species. Accordingly, we described the males of L. birmanicus for the first time, redescribed its female, using newly collected specimens from Yadò, Than Taung and Kalekho Atet townships, Kayin State. We also provided information on the variation in genital morphology of both species, and their relationships within the birmanicus-group of species.

Three new species of the segmented spider genus Qiongthela (Mesothelae, Liphistiidae) from Hainan Island, China

We report three new species of the segmented trapdoor spider genus Qiongthela Xu & Kuntner, 2015 collected from Hainan Island, China based on morphological characters: Q.dongfangsp. nov. (♂♀), Q.nankaisp. nov. (♂♀), Q.yalinsp. nov. (♂♀). We also provide the GenBank accession codes of the DNA barcode gene, cytochrome c oxidase subunit I (COI), of the type specimens of all three new species to aid future identification.

Phylogenomic Analysis of Ultraconserved Elements Resolves the Evolutionary and Biogeographic History of Segmented Trapdoor Spiders

The segmented trapdoor spiders (Liphistiidae) are the sole surviving family of the suborder Mesothelae, which forms the sister lineage to all other living spiders. Liphistiids have retained a number of plesiomorphic traits and their present-day distribution is limited to East and Southeast Asia. Studying this group has the potential to shed light on the deep evolutionary history of spiders, but the phylogeny and divergence times of the family have not been resolved with confidence. We performed phylogenomic and molecular dating analyses of 2,765 ultraconserved element loci from 185 liphistiid taxa. Our analyses show that the crown group of Liphistiidae appeared in the mid-Cretaceous at 102 Ma (95% credibility interval 92-113 Ma), but it was not until the Neogene that much of the diversification within the family occurred in mainland Southeast and East Asia. This diversification was coincident with tectonic events such as the extension of the East Asian continental margin, as well as geological upheavals in Indochina induced by the collision between India and Asia. Our study highlights the important role of major tectonic events in shaping the evolutionary history, present-day diversity, and geographical distribution of mesothele and liphistiid spiders.

Molecular species delimitation in the primitively segmented spider genus Heptathela endemic to Japanese islands

Determining species boundaries forms an important foundation for biological research. However, the results of molecular species delimitation can vary with the data sets and methods that are used. Here we use a two-step approach to delimit species in the genus Heptathela, a group of primitively segmented trapdoor spiders that are endemic to Japanese islands. Morphological evidence suggests the existence of 19 species in the genus. We tested this initial species hypothesis by using six molecular species-delimitation methods to analyse 180 mitochondrial COI sequences of Heptathela sampled from across the known range of the genus. We then conducted a set of more focused analyses by sampling additional genetic markers from the subset of taxa that were inconsistently delimited by the single-locus analyses of mitochondrial DNA. Multilocus species delimitation was performed using two Bayesian approaches based on the multispecies coalescent. Our approach identified 20 putative species among the 180 sampled individuals of Heptathela. We suggest that our two-step approach provides an efficient strategy for delimiting species while minimizing costs and computational time.

Two new species of the primitively segmented spider genus Songthela from Hunan Province, China (Mesothelae, Liphistiidae)

This study reports two new species of the primitively segmented spider genus Songthela from Hunan Province, China, based on morphological characters: S.huangyangsp. nov. (♂♀), S.xiangnansp. nov. (♂♀). Additional material also facilitates a more accurate description of S.goulouensis (Yin, 2001) with the first description of the male. Nucleotide data for the barcoding gene, cytochrome c oxidase subunit I (COI), is also provided for these three species.

Four new species of the primitively segmented spider genus Qiongthela from Hainan Island, China (Mesothelae, Liphistiidae)

The primitively segmented spider genus Qiongthela Xu & Kuntner, 2015 consists of seven species that are distributed in Hainan Island, China and southern Vietnam. Of the seven species, five are known from Hainan Island. In this study, four more Qiongthela species collected from Hainan Island are diagnosed and described as new to science based on morphological characters: Q. baoting sp. nov. (♂♀), Q. qiongzhong sp. nov. (♂♀), Q. sanya sp. nov. (♂♀), Q. yinggezui sp. nov. (♂♀). To facilitate future identification, the GenBank accession codes of the DNA barcode gene, cytochrome c oxidase subunit I (COI), for all the type specimens are also provided.

A taxonomic monograph of the liphistiid spider genus Heptathela, endemic to Japanese islands

Among the eight extant genera of primitively segmented spiders, family Liphistiidae, two are confined to East Asian islands, Heptathela Kishida, 1923 and Ryuthela Haupt, 1983. In this paper, a taxonomic revision of the genus Heptathela (Heptathelinae) from Kyushu and Ryukyu archipelago, Japan is provided. This study follows a multi-tier species delimitation strategy within an integrative taxonomic framework that is presented in a parallel paper, in which diagnosable lineages are considered as valid species. There, the initial hypothesis of species diversity (19) based on classical morphological diagnoses is tested with multiple species delimitation methods aimed at resolving conflict in data. This revision follows those analyses that converge on the species diversity of 20, which includes a pair of cryptic species that would have been undetected with morphology alone. After this revision, eight previously described species remain valid, two junior synonyms are proposed, and 12 new Heptathela species are described based on diagnostic evidence. To ease identification and to hint at putative evolutionary units, Heptathela is divided into three groups. The Kyushu group contains H.higoensis Haupt, 1983, H.kikuyai Ono, 1998, H.kimurai (Kishida, 1920), and H.yakushimaensis Ono, 1998; the Amami group contains H.amamiensis Haupt, 1983, H.kanenoi Ono, 1996, H.kojimasp. nov., H.sumiyosp. nov., and H.ukensp. nov.; and the Okinawa group contains H.yanbaruensis Haupt, 1983, H.ahasp. nov., H.gayozansp. nov., H.kubayamasp. nov., H.maesp. nov., H.otohasp. nov., H.shurisp. nov., H.tokashikisp. nov., H.untensp. nov., and H.cryptasp. nov.Heptathelahelios Tanikawa & Miyashita, 2014 is not assigned to a species group. A combination of diagnostic tools augments the morphological diagnoses that, in isolation, would be prone to error in morphologically challenging groups of organisms.

Two new species of the primitively segmented spider genus Liphistius Schiödte, 1849 (Mesothelae, Liphistiidae) from Myanmar

Two Liphistius species of the primitively segmented spider family Liphistiidae, collected from Loikaw (Kayah State) and Pinlaung (Shan State), Myanmar, are diagnosed and described as new to science based on their genital morphology: Liphistiushprusosp. nov. (♀), Liphistiuspinlaungsp. nov. (♂♀).

Biogeography of the Caribbean Cyrtognatha spiders

Island systems provide excellent arenas to test evolutionary hypotheses pertaining to gene flow and diversification of dispersal-limited organisms. Here we focus on an orbweaver spider genus Cyrtognatha (Tetragnathidae) from the Caribbean, with the aims to reconstruct its evolutionary history, examine its biogeographic history in the archipelago, and to estimate the timing and route of Caribbean colonization. Specifically, we test if Cyrtognatha biogeographic history is consistent with an ancient vicariant scenario (the GAARlandia landbridge hypothesis) or overwater dispersal. We reconstructed a species level phylogeny based on one mitochondrial (COI) and one nuclear (28S) marker. We then used this topology to constrain a time-calibrated mtDNA phylogeny, for subsequent biogeographical analyses in BioGeoBEARS of over 100 originally sampled Cyrtognatha individuals, using models with and without a founder event parameter. Our results suggest a radiation of Caribbean Cyrtognatha, containing 11 to 14 species that are exclusively single island endemics. Although biogeographic reconstructions cannot refute a vicariant origin of the Caribbean clade, possibly an artifact of sparse outgroup availability, they indicate timing of colonization that is much too recent for GAARlandia to have played a role. Instead, an overwater colonization to the Caribbean in mid-Miocene better explains the data. From Hispaniola, Cyrtognatha subsequently dispersed to, and diversified on, the other islands of the Greater, and Lesser Antilles. Within the constraints of our island system and data, a model that omits the founder event parameter from biogeographic analysis is less suitable than the equivalent model with a founder event.

Origin of spiders and their spinning organs illuminated by mid-Cretaceous amber fossils

Understanding the genealogical relationships among the arachnid orders is an onerous task, but fossils have aided in anchoring some branches of the arachnid tree of life. The discovery of Palaeozoic fossils with characters found in both extant spiders and other arachnids provided evidence for a series of extinctions of what was thought to be a grade, Uraraneida, that led to modern spiders. Here, we report two extraordinarily well-preserved Mesozoic members of Uraraneida with a segmented abdomen, multi-articulate spinnerets with well-defined spigots, modified male palps, spider-like chelicerae and a uropygid-like telson. The new fossils, belonging to the species Chimerarachne yingi, were analysed phylogenetically in a large data matrix of extant and extinct arachnids under a diverse regime of analytical conditions, most of which resulted in placing Uraraneida as the sister clade of Araneae (spiders). The phylogenetic placement of this arachnid fossil extends the presence of spinnerets and modified palps more basally in the arachnid tree than was previously thought. Ecologically, the new fossil extends the record of Uraraneida 170 million years towards the present, thus showing that uraraneids and spiders co-existed for a large fraction of their evolutionary history.

Four new species of the primitively segmented spider genus Qiongthela from Hainan island, China (Mesothelae, Liphistiidae)

Four species of the primitively segmented spider genus Qiongthela Xu & Kuntner, 2015 collected from Hainan Island, China are diagnosed and described as new to science based on their genital morphology: Q. bawangsp. n. (♀), Q. jianfengsp. n. (♂♀), Q. yinisp. n. (♀), Q. wuzhisp. n. (♂♀). Together with the type species of Qiongthela, Q. baishensis Xu, 2015, five species are found and described from Hainan, China, and seven species are now known in the genus.

Extant primitively segmented spiders have recently diversified from an ancient lineage

Living fossils are lineages that have retained plesiomorphic traits through long time periods. It is expected that such lineages have both originated and diversified long ago. Such expectations have recently been challenged in some textbook examples of living fossils, notably in extant cycads and coelacanths. Using a phylogenetic approach, we tested the patterns of the origin and diversification of liphistiid spiders, a clade of spiders considered to be living fossils due to their retention of arachnid plesiomorphies and their exclusive grouping in Mesothelae, an ancient clade sister to all modern spiders. Facilitated by original sampling throughout their Asian range, we here provide the phylogenetic framework necessary for reconstructing liphistiid biogeographic history. All phylogenetic analyses support the monophyly of Liphistiidae and of eight genera. As the fossil evidence supports a Carboniferous Euramerican origin of Mesothelae, our dating analyses postulate a long eastward over-land dispersal towards the Asian origin of Liphistiidae during the Palaeogene (39-58 Ma). Contrary to expectations, diversification within extant liphistiid genera is relatively recent, in the Neogene and Late Palaeogene (4-24 Ma). While no over-water dispersal events are needed to explain their evolutionary history, the history of liphistiid spiders has the potential to play prominently in vicariant biogeographic studies.