Article

Molecular phylogeny of pimoid spiders and the limits of Linyphiidae, with a reassessment of male palpal homologies (Araneae, Pimoidae)

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Abstract

We address the phylogenetic relationships of pimoid spiders (Pimoidae) using a standard target-gene approach with an extensive taxonomic sample, which includes representatives of the four currently recognized pimoid genera, 26 linyphiid genera, a sample of Physoglenidae, Cyatholipidae and one Tetragnathidae species. We test the monophyly of Pimoidae and Linyphiidae and explore the biogeographic history of the group. Nanoa Hormiga, Buckle and Scharff, 2005 and Pimoa Chamberlin & Ivie, 1943 form a clade which is the sister group of a lineage that includes all Linyphiidae, Weintrauboa Hormiga, 2003 and Putaoa Hormiga and Tu, 2008. Weintrauboa, Putaoa, Pecado and Stemonyphantes form a clade (Stemonyphantinae) sister to all remaining linyphiids. We use the resulting optimal molecular phylogenetic tree to assess hypotheses on the male palp sclerite homologies of pimoids and linyphiids. Pimoidae is redelimited to only include Pimoa and Nanoa. We formalize the transfer from Pimoidae of the genera Weintrauboa and Putaoa to Linyphiidae, re-circumscribe the linyphiid subfamily Stemonyphantinae, and offer revised morphological diagnoses for Pimoidae and Linyphiidae.

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... It is common in systematics that a high-level molecular phylogeny may significantly conflict with the established taxonomic system based on morphological characters [1][2][3][4]. Understanding the evolutionary past that shaped the species diversity of lineages always attracts the interest of biologists [5][6][7][8]. Spiders are generalist predators, forming a successful terrestrial animal group, and their high species diversity is distributed unevenly across lineages [9], even extremely asymmetrically between sister groups [4,10]. Several hypotheses have been proposed to interpret the driving forces that promote spider diversification, such as co-diversification with insects [11][12][13], key innovations in silk structure and web architecture [10], repeated evolution of the respiratory system from book lungs to tracheae [14], and foraging changes from using capturing web to cursorial habits [15]. ...
... Four of them, Linyphiinae, Erigoninae, Micronetinae, and Ipainae, were not monophyletic groups; the representatives of Mynogleninae and Dubiaraneinae fell into Linyphiinae; the Stemonyphantinae taxa were often clustered with pimoids, the sister group of linyphiids [1,4,[19][20][21]. The subfamily Stemonyphantinae was newly revised by adding two ex-pimoid genera and another linyphiid genus in it [8]. However, the seven-clade topology of molecular phylogenies are robustly supported, and all of these seven major clades (clades A-F and S in [4]) are supported by some putative synapomorphic characters. ...
... Pimoidae is the sister group of Linyphiidae and often used as outgroups for rooting. Given the recent revision of Pimoidae having the formerly pimoid genera Putaoa and Weintrauboa transferred to Linyphiidae, and redelimited Pimoidae as including only Pimoa and Nanoa [8], we also added representatives of Pimoa and Putaoa into the dataset. The final data set consisted of 127 taxa, including 13 Solenysa taxa, 113 other linyphiids, and one pimoid. ...
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... The spider family Pimoidae Wunderlich, 1986 includes 82 species belonging to two genera: Nanoa Hormiga, Buckle & Scharff, 2005 (one species from U.S.A.) and Pimoa Chamberlin & Ivie, 1943 (81 species from North America, Asia and South Europe) (World Spider Catalog 2021). Hormiga et al. (2021) revised the Pimoidae based on molecular phylogeny and transferred two genera (Putaoa Tu, 2008 andWeintrauboa Hormiga, 2003) to the family Linyphiidae. ...
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The spermatozoa of spiders (Araneae) show a high structural diversity, resulting in several potential phylogenetic characters. In the present paper, we describe the spermatozoa of the spider family Pimoidae for the first time. We investigate four species of the genus Pimoa (P. altioculata, P. curvata, P. laurae, and P. edenticulata) by means of light and transmission electron microscopy. The male reproductive system consists of paired testes and long convoluted paired deferent ducts. The spermatozoa are generally characterized by: (1) a cylindrical acrosomal vacuole, (2) an acrosomal filament restricted to the precentriolar part of the nucleus, (3) a nuclear canal running in the periphery but projecting towards the posterior portion of the nucleus, (4) a short postcentriolar elongation of the nucleus, (5) a 9+0 axonemal pattern, and (6) cleistospermia as transfer form. The organization of the axoneme is of particular phylogenetic interest, since a 9+0 axonemal pattern was described within spiders only for the megadiverse family Linyphiidae, the sister group of Pimoidae. We have reconstructed the evolution of the axoneme using comparative spermatozoal data for 54 orbicularian species representing 11 families. We propose that the 9+0 axonemal pattern is a new synapomorphy for Pimoidae + Linyphiidae. The phylogenetic and evolutionary implications of other potential sperm characters (e.g., length of the postcentriolar elongation of the nucleus) are discussed.
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Weintrauboa yele new species (Pimoidae) is described and illustrated based on specimens collected in China. The taxonomic status and distribution of Weintrauboa insularis (Saito, 1935) new combination and of W. chikunii (Oi, 1979) are discussed and the former species is illustrated based on specimens from the Sakhalin islands. Parsimony analysis of morphological characters provides support for the monophyly of Weintrauboa and for its sister group relationship to the genus Putaoa Hormiga and Tu, 2008. Some comments on the phylogenetic placement of the recently erected family “Sinopimoidae” are provided.
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The spider genus Putaoa new genus (Araneae, Pimoidae) is described to place two species of pimoids from China, Putaoa huaping new species (the type species) and P. megacantha (Xu & Li, 2007) new combination. Parsimony analysis of morphological characters provides support for the monophyly of Putaoa and for its sister group relationship to the genus Weintrauboa Hormiga, 2003 and corroborates the monophyly of Pimoidae.
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Dating back to almost 400 mya, spiders are among the most diverse terrestrial predators [1]. However, despite considerable effort [1-9], their phylogenetic relationships and diversification dynamics remain poorly understood. Here, we use a synergistic approach to study spider evolution through phylogenomics, comparative transcriptomics, and lineage diversification analyses. Our analyses, based on ca. 2,500 genes from 159 spider species, reject a single origin of the orb web (the "ancient orb-web hypothesis") and suggest that orb webs evolved multiple times since the late Triassic-Jurassic. We find no significant association between the loss of foraging webs and increases in diversification rates, suggesting that other factors (e.g., habitat heterogeneity or biotic interactions) potentially played a key role in spider diversification. Finally, we report notable genomic differences in the main spider lineages: while araneoids (ecribellate orb-weavers and their allies) reveal an enrichment in genes related to behavior and sensory reception, the retrolateral tibial apophysis (RTA) clade-the most diverse araneomorph spider lineage-shows enrichment in genes related to immune responses and polyphenic determination. This study, one of the largest invertebrate phylogenomic analyses to date, highlights the usefulness of transcriptomic data not only to build a robust backbone for the Spider Tree of Life, but also to address the genetic basis of diversification in the spider evolutionary chronicle.
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The boreotropics hypothesis postulates a preferential tropical biotic interchange between North America and Eurasia during the early Tertiary that was directed by Eocene thermal maxima and the close proximity of these two continental plates. This preferential interchange occurred at a time when South America was geologically and biotically isolated. A prediction of this hypothesis posits that a taxon with a present-day center of diversity in tropical North America, and with an early Tertiary fossil record from any region there, has a high probability of having sister-group relatives in the Paleotropics and derived relatives in South America. We propose a test of this prediction with phylogenetic studies of two pantropical taxa of Leguminosae that have early Tertiary North American fossil records. Our findings are consistent with the boreotropics hypothesis, and additional evidence suggests that many tropical elements in North America could be descendants of northern tropical progenitors. Ramifications of this hypothesis include the importance of integrating the fossil record with cladistic biogeographic studies, theoretical bases for recognizing tropical taxa with such disjunct distributions as Mexico and Madagascar, identification of taxa that may be most useful for testing vicariance models of Caribbean biogeography, and integrating the study of disjunct distributions in temperate regions of the northern hemisphere with those in the neo- and paleotropics.
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Model-based molecular phylogenetics plays an important role in comparisons of genomic data, and model selection is a key step in all such analyses. We present ModelFinder, a fast model-selection method that greatly improves the accuracy of phylogenetic estimates by incorporating a model of rate heterogeneity across sites not previously considered in this context and by allowing concurrent searches of model space and tree space.
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Pimoidae is a small family of araneoid spiders, hitherto represented in Europe by two species with disjunct distribution in the Alps and in the Cantabrian Mountains of northern Spain. Here we report the description of two additional European species of Pimoa, discovered within the range of the only former alpine species, P. rupicola: P. graphitica sp. nov. and P. delphinica sp. nov. The new species are distinguished from the latter by genitalic characters as well as by molecular characters. On the basis of the re-examination of old and recent abundant material collected in caves and other subterranean habitats, we revise the distribution patterns of the genus Pimoa in the Alps and outline the species distribution ranges. Molecular data suggest the existence of gene flow between populations of the two new species when in sympatry. The different species probably originated in the alpine region as a result of range contractions following dramatic climatic changes in the Alps since the mid Miocene. We interpreted the present-day overlapping distribution in light of a possible postglacial expansion. Finally, we provide insights on the natural history and life cycles of the new species and discuss their phylogenetic relationships within Pimoidae.
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For high-level molecular phylogenies, a comprehensive sampling design is a key factor for not only improving inferential accuracy, but also for maximizing the explanatory power of the resulting phylogeny. Two standing problems in molecular phylogenies are the unstable placements of some deep and long branches, and the phylogenetic relationships shown by robust supported clades conflict with recognized knowledge. Empirical and theoretical studies suggest that increasing taxon sampling is expected to ameliorate, if not resolve, both problems; however, neither the current taxonomic system nor the established phylogeny provides sufficient information to guide additional sampling design. We examined the phylogeny of the spider family Linyphiidae, and selected ingroup species based on epigynal morphology, which can be reconstructed in a phylogenetic context. Our analyses resulted in seven robustly supported clades within linyphiids. The placements of four deep and long branches are sensitive to variations in both outgroup and ingroup sampling, suggesting the possibility of long branch attraction artifacts. Results of ancestral state reconstruction indicate that successive state transformations of the epigynal plate are associated with early cladogenetic events in linyphiid diversification. Representatives of different subfamilies were mixed together within well supported clades and examination revealed that their defining characters, as per traditional taxonomy, are homoplastic. Furthermore, our results demonstrated that increased taxon sampling produced a more informative framework, which in turn helps to study character evolution and interpret the relationships among linyphiid lineages. Additional defining characters are needed to revise the linyphiid taxonomic system based on our phylogenetic hypothesis. Copyright © 2015 Elsevier Inc. All rights reserved.
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This is the first genus‐level phylogeny of the subfamily Mynogleninae. It is based on 190 morphological characters scored for 44 taxa: 37 mynoglenine taxa (ingroup) representing 15 of the 17 known genera and seven outgroup taxa representing the subfamilies Stemonyphantinae, Linyphiinae (Linyphiini and Micronetini), and Erigoninae, and a representative of the family Pimoidae, the sister‐group to Linyphiidae. No fewer than 147 of the morphological characters used in this study are new and defined for this study, and come mainly from male and female genitalia. Parsimony analysis with equal weights resulted in three most parsimonious trees of length 871. The monophyly of the subfamily Mynogleninae and the genera Novafroneta, Parafroneta, Laminafroneta, Afroneta, Promynoglenes, Metamynoglenes, and Haplinis are supported, whereas Pseudafroneta is paraphyletic. The remaining seven mynoglenine genera are either monotypic or represented by only one taxon. Diagnoses are given for all genera included in the analysis. The evolution of morphological traits is discussed and we summarize the diversity and distribution patterns of the 124 known species of mynoglenines. The preferred topology suggests a single origin of mynoglenines in New Zealand with two dispersal events to Africa, and does not support Gondwana origin.
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True rosefinches (Aves: Carpodacus) are restricted to Eurasia, and 19 out of 25 species occur in the Sino- Himalayas, making this the likely centre of origin. To test this hypothesis, suggested species splits had to be evaluated and potential further cryptic diversity unravelled. A taxon-complete dated molecular phylogeny was reconstructed using maximum-likelihood and Bayesian methods. Maximum-parsimony and likelihood approaches were applied to deduce ancestral areas. Rosefinches, including the widespread Carpodacus erythrinus (Pallas, 1770), originated in south-west China (and the Himalayas) 14 Mya, and gave rise to a smaller clade consisting of C. erythrinus, Haematospiza sipahi (Hodgson, 1836), and Chaunoproctus ferreorostris (Vigors, 1829), and a larger clade with 22 species. The latter split into four major lineages through vicariance during the uplift of the Himalayas. The suggested species splits of dubius from Carpodacus thura Bonaparte & Schlegel, 1850, formosanus from Carpodacus vinaceus Verreaux, 1871, grandis from Carpodacus rhodochlamys Brandt, 1843, verreauxii from Carpodacus rodopeplus (Vigors, 1831) (even polyphyletic) could be supported, whereas the suggested split of severtzovi from Carpodacus rubicilla (Güldenstädt, 1775) appears to be too young, and should be considered intraspecific. On the other hand, the central Asian lineage of Carpodacus synoicus Temminck, 1825 deserves species rank [Carpodacus stolickae (Hume, 1874)]. The Carpodacus eos/pulcherrimus complex consists of four lineages, pulcherrimus/argyrophrys and davidianus [Carpodacus pulcherrimus s.s. (Moore, 1856)], and eos and waltoni [Carpodacus waltoni (Sharpe, 1905)].
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This study presents a new phylogeny of erigonine spiders with emphasis on genera from the Neotropics. Thirty-nine exemplar taxa representing mostly Neotropical genera were added to a global sample of 31 erigonine and 12 outgroup exemplar taxa analyzed in a previous study. These 82 taxa were coded for 176 (172 informative) mostly morphological characters. Eighty-one characters were identical to or modified from the 73 (67 informative) characters included in a previous study; the remaining 95 characters are new. The complete data set includes 70 erigonine exemplars representing 65 genera, seven nonerigonine linyphiid exemplars, and five exemplars representing four araneoid families in the outgroup. Cladistic analysis resulted in a single most parsimonious tree (L =904, CI = 0.23, RI = 0.58; uninformative characters excluded: L = 900, CI = 0.23). This paper explores the implications of the new topology for the evolution of several characters of interest in erigonine evolution. The phylogeny implies that the desmitracheate condition is a synapomorphy of erigonines, with a reversal to the haplotracheate condition in one large clade within Erigoninae. We infer that the loss of the paracymbium in Neotropical erigonines occurred twice and may have progressed by different evolutionary pathways. Our phylogeny differs markedly from the previous cladistic hypothesis of erigonine relationships. We investigate how the addition of characters and taxa (alone and together) have altered the earlier hypothesis of erigonine phylogeny. We conclude that topological changes from the previous study to the current one are largely the result of adding and modifying characters, not adding taxa. Continuous Jackknife Function (CJF) analysis predicts that the inclusion of additional character data will continue to imply changes in the relationships among taxa in our analysis.
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INTRODUCTION The very small genus Stemonyphantes up to our present knowledge is restricted to the temperate regions of Europe, Asia and North America. It was created by Menge (1866) for the European species Aranea trilineata Linnaeus, 1767, which, among others, appeared to be a junior synonym of Aranea lineata Linnaeus, 1758. The species was recorded also from North America (Emerton, 1876, 1882; Keyserling, 1886; and others). For nearly seventy years the nearctic population was thought to be conspecific with the palaearctic population. Keyserling (1886) even supposed the species to have been imported by ship from Europe and to have spread from there. A detailed description of S. lineatus, furnished with excellent figures of the genitalia of the species, was given by Blauvelt (1936) still without any indication of differences between European and North American specimens, although she states to have seen them from both regions. Gertsch (1951) was first in drawing attention to differences between the two populations; he created the new name Stemonyphantes blauveltae for the nearctic population. In Europe a new variety S. bucculentus [ = lineatus] pictus was described by Schenkel (1930) from the Riesengebirge on the Polish-Czechoslovakian frontier. Schenkel only possessed a female specimen, which differed from the nominate form mainly in the colour of the cephalothorax and abdomen. More specimens, including a male, were recorded by Buchar (1967) from the Böhmerwald in Czechoslovakia near the German frontier. Buchar examined the genitalia of these specimens and decided to raise Schenkel's variety to specific rank. He redescribed the species and listed the main differences with S. lineatus.
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Using the most up-to-the-date information available, we present a considerably revised plate tectonic and paleogeographic model for the Indian Ocean bordering continents, from Gondwana's Middle Jurassic break-up through to India's collision with Asia in the middle Cenozoic. The landmass framework is then used to explore the sometimes complex and occasionally counter-intuitive patterns that have been observed in the fossil and extant biological records of India, Madagascar, Africa and eastern Eurasia, as well those of the more distal continents.
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A new fossil Linyphiidae: Linyphiinae is described from 125–135 Ma old (Upper Neocomian–basal Lower Aptian) Cretaceous amber from the Kdeirji/Hammana outcrop, Lebanon. This is the oldest known linyphiid as well as the oldest described amber spider. The first major radiation of the linyphiid subfamilies occurred in the early Cretaceous, if not before, and the presence of Linyphiidae in this period predicts the presence of Pimoidae then too. Current evidence, which suggests the higher araneoids did not radiate and diversify until after the end-Cretaceous mass extinction event may be an artefact of sample size.
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The male palpal organs of 124 British species of linyphiid spiders are described in detai, by reference to two basic types of palp structure (simple and complex). The history of the taxonomy of the family is described, with reference especially to the work of Simon, Hull, Petrunkevitch, Locket & Millidge, and Wiehle.
Article
This paper provides the first quantitative cladistic analysis of linyphiid morphology. Classical and novel homology hypotheses for a variety of character systems (male and female genitalia, somatic morphology, spinneret silk spigot morphology, etc.) are critically examined and studied within a phylogenetic context. Critical characters have been illustrated. A sample of linyphiid taxa (nine genera in four subfamilies), five species of Pimoa (Pimoidae), and two other araneoid families (Tetragnathidae and Araneidae, represented by Tetragnatha and Zygiella, respectively) were used to study the implications of the phylogeny of Pimoidae for the systematics of linyphiids. The phylogenetic relationships of these 16 exemplar taxa, as coded for the 47 characters studied, were analysed using numerical cladistic methods. In the preferred cladogram Pimoidae and Linyphiidae are sister groups, Stemonyphantinae are sister group to the remaining linyphiids, and Mynogleninae are sister group to the clade composed of Erigoninae plus Linyphiinae. These results agree with the relationships recently proposed by Wunderlich, except by finding erigonines as the sister group to linyphiines rather than to mynoglenines.
Article
The genus Labulla Simon is circumscribed in phylogenetic terms to include the species Labulla thoracica (Wider), L. flahaulti Simon and L. machadoi sp. nov. The genital anatomy of the genus is described in detail and the taxonomy of the genus is reviewed. The monophyly of Labulla is supported by numerous morphological apomorphies of the male palp and female epigynum. Based on a cladistic analysis, a new genus, Pecado gen. nov., is erected to place Labulla impudica Denis, from Northern Africa. Lepthyphantes insularis Saito and ‘Labulla’nepula Tikader, both formerly included in Labulla, are not congeneric with the type species of Labulla. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 143, 359–404.
Article
The spider genus Weintrauboa new genus (Araneae, Pimoidae) is described to place two species of pimoids from Japan and adjacent islands that were formerly classified in the linyphiid genus Labulla. Weintrauboa contortipes (Karsch) new comb., the type species, and W. chikunii (Oi) new comb. are redescribed. Parsimony analysis of morphological characters provides robust support for the monophyly of the genus Weintrauboa and corroborates the monophyly of Pimoa, Pimoidae, and the clade Linyphiidae plus Pimoidae. New diagnoses for Pimoa and Pimoidae are provided. © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 139, 261–281
Article
The spider genus Nanoa gen. nov. (Araneae, Pimoidae) is described to place Nanoa enana, a new species of pimoids from Western North America. Parsimony analysis of morphological characters provides support for the monophyly of Pimoa plus Nanoa and corroborates the monophyly of Pimoidae and of the clade Linyphiidae plus Pimoidae. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 249–262.
Article
This study infers the higher-level cladistic relationships of linyphiid spiders from five genes (mitochondrial CO1, 16S; nuclear 28S, 18S, histone H3) and morphological data. In total, the character matrix includes 47 taxa: 35 linyphiids representing the currently used subfamilies of Linyphiidae (Stemonyphantinae, Mynogleninae, Erigoninae, and Linyphiinae (Micronetini plus Linyphiini)) and 12 outgroup species representing nine araneoid families (Pimoidae, Theridiidae, Nesticidae, Synotaxidae, Cyatholipidae, Mysmenidae, Theridiosomatidae, Tetragnathidae, and Araneidae). The morphological characters include those used in recent studies of linyphiid phylogenetics, covering both genitalic and somatic morphology. Different sequence alignments and analytical methods produce different cladistic hypotheses. Lack of congruence among different analyses is, in part, due to the shifting placement of Labulla, Pityohyphantes, Notholepthyphantes, and Pocobletus. Almost all combined analyses agree on the monophyly of linyphioids, Pimoidae, Linyphiidae, Erigoninae, Mynogleninae, as well as Stemonyphantes as a basal lineage within Linyphiidae. Our results suggest independent origins of the desmitracheate tracheal system in micronetines and erigonines, and that erigonines were primitively haplotracheate. Cephalothoracic glandular specializations of erigonines and mynoglenines apparently evolved independently. Subocular sulci of mynoglenines and lateral sulci (e.g. Bathyphantes) evolved independently but glandular pores in the prosoma proliferated once. The contribution of different character partitions and their sensitivity to changes in traditional analytical parameters is explored and quantified. © The Willi Hennig Society 2009.