This phylogenetic analysis of 3 1 exemplar taxa treats the 12 families ofhaneoidea (Anapidae, Araneidae, Cyatholipidae, Linyphiidae, Mysmenidae, Nesticidae, Pimoidae, Symphytognathidae, Synotaxidae, Tetragnathidae, Theridiidae, and Theridiosomatidae). The data set comprises 93 characters: 23 from male genitalia, 3 from female genitalia, 18 from cephalothorax morphology, 6 from abdomen morphology, 14 from limb morphology, 15 from the spinnerets, and 14 from web architecture and other behaviour. Criteria for tree choice were minimum length parsimony and parsimony under implied weights. The outgroup for Araneoidea is Deinopoidea (Deinopidae and Uloboridae). The preferred shortest tree specifies the relationships ((Uloboridae, Deinopidae) (Araneidae (Tetragnathidae ((Theridiosomatidae (Mysmenidae (Symphytognathidae, Anapidae))) ((Linyphiidae, Pimoidae) ((Theridiidae, Nesticidae) (Cyatholipidae, Synotaxidae))))))). The monophyly of Tetragnathidae (including metines and nephilines), the symphytognathoids, theridiid-nesticid lineage, and Synotaxidae are confirmed. Cyatholipidae are sister to Synotaxidae, not closely related to either the Araneidae or Linyphiidae, as previously suggested. Four new clades are proposed: the cyatholipoids (Cyatholipidae plus Synotaxidae), the 'spineless femur clade' (theridioid lineage plus cyatholipoids), the 'araneoid sheet web builders' (linyphioids plus the spineless femur clade), and the 'reduced piriform clade' (symphytognathoids plus araneoid sheet web builders). The results imply a coherent scenario for web evolution in which the monophyletic orb gives rise to the monophyletic araneoid sheet, which in turn gives rise to the gumfoot web of the theridiid-nesticid lineage. While the spinning complement of single pairs of glands does not change much over the evolution of the group, multiple sets of glands are dramatically reduced in number, implying that derived araneoids are incapable of spinning many silk fibers at the same time. 0 1998 The 1,innean Society of London ADDITIONAL

We present a phylogenetic analysis of spiders using a dataset of 932 spider species, representing 115 families (only the family Synaphridae is unrepresented), 700 known genera, and additional representatives of 26 unidentified or undescribed genera. Eleven genera of the orders Amblypygi, Palpigradi, Schizomida and Uropygi are included as outgroups. The dataset includes six markers from the mitochondrial (12S, 16S, COI) and nuclear (histone H3, 18S, 28S) genomes, and was analysed by multiple methods, including constrained analyses using a highly supported backbone tree from transcriptomic data. We recover most of the higher‐level structure of the spider tree with good support, including Mesothelae, Opisthothelae, Mygalomorphae and Araneomorphae. Several of our analyses recover Hypochilidae and Filistatidae as sister groups, as suggested by previous transcriptomic analyses. The Synspermiata are robustly supported, and the families Trogloraptoridae and Caponiidae are found as sister to the Dysderoidea. Our results support the Lost Tracheae clade, including Pholcidae, Tetrablemmidae, Diguetidae, Plectreuridae and the family Pacullidae (restored status) separate from Tetrablemmidae. The Scytodoidea include Ochyroceratidae along with Sicariidae, Scytodidae, Drymusidae and Periegopidae; our results are inconclusive about the separation of these last two families. We did not recover monophyletic Austrochiloidea and Leptonetidae, but our data suggest that both groups are more closely related to the Cylindrical Gland Spigot clade rather than to Synspermiata. Palpimanoidea is not recovered by our analyses, but also not strongly contradicted. We find support for Entelegynae and Oecobioidea (Oecobiidae plus Hersiliidae), and ambiguous placement of cribellate orb‐weavers, compatible with their non‐monophyly. Nicodamoidea (Nicodamidae plus Megadictynidae) and Araneoidea composition and relationships are consistent with recent analyses. We did not obtain resolution for the titanoecoids (Titanoecidae and Phyxelididae), but the Retrolateral Tibial Apophysis clade is well supported. Penestomidae, and probably Homalonychidae, are part of Zodarioidea, although the latter family was set apart by recent transcriptomic analyses. Our data support a large group that we call the marronoid clade (including the families Amaurobiidae, Desidae, Dictynidae, Hahniidae, Stiphidiidae, Agelenidae and Toxopidae). The circumscription of most marronoid families is redefined here. Amaurobiidae include the Amaurobiinae and provisionally Macrobuninae. We transfer Malenellinae (Malenella, from Anyphaenidae), Chummidae (Chumma) (new syn.) and Tasmarubriinae (Tasmarubrius, Tasmabrochus and Teeatta, from Amphinectidae) to Macrobuninae. Cybaeidae are redefined to include Calymmaria, Cryphoeca, Ethobuella and Willisius (transferred from Hahniidae), and Blabomma and Yorima (transferred from Dictynidae). Cycloctenidae are redefined to include Orepukia (transferred from Agelenidae) and Pakeha and Paravoca (transferred from Amaurobiidae). Desidae are rede...

Chelicerata represents one of the oldest groups of arthropods, with a fossil record extending to the Cambrian, and is sister group to the remaining extant arthropods, the mandibulates. Attempts to resolve the internal phylogeny of chelicerates have achieved little consensus, due to marked discord in both morphological and molecular hypotheses of chelicerate phylogeny. The monophyly of Arachnida, the terrestrial chelicerates, is generally accepted, but has garnered little support from molecular data, which have been limited either in breadth of taxonomic sampling or in depth of sequencing. To address the internal phylogeny of this group, we employed a phylogenomic approach, generating transcriptomic data for 17 species in combination with existing data, including two complete genomes. We analyzed multiple data sets containing up to 1,235,912 sites across 3,644 loci, using alternative approaches to optimization of matrix composition. Here, we show that phylogenetic signal for the monophyly of Arachnida is restricted to the 500 slowest-evolving genes in the data set. Accelerated evolutionary rates in Acariformes, Pseudoscorpiones, and Parasitiformes potentially engender long-branch attraction artifacts, yielding nonmonophyly of Arachnida with increasing support upon incrementing the number of concatenated genes. Mutually exclusive hypotheses are supported by locus groups of variable evolutionary rate, revealing significant conflicts in phylogenetic signal. Analyses of gene-tree discordance indicate marked incongruence in relationships among chelicerate orders, whereas derived relationships are demonstrably robust. Consistently recovered and supported relationships include the monophyly of Chelicerata, Euchelicerata, Tetrapulmonata, and all orders represented by multiple terminals. Relationships supported by subsets of slow-evolving genes include Ricinulei + Solifugae; a clade comprised of Ricinulei, Opiliones, and Solifugae; and a clade comprised of Tetrapulmonata, Scorpiones, and Pseudoscorpiones. We demonstrate that outgroup selection without regard for branch length distribution exacerbates long-branch attraction artifacts and does not mitigate gene-tree discordance, regardless of high gene representation for outgroups that are model organisms. Arachnopulmonata (new name) is proposed for the clade comprising Scorpiones + Tetrapulmonata (previously named Pulmonata).

Details of web-construction behaviour and morphology support the monophyly of nephiline spiders with Phonognatha as the sister-group to the remaining nephiline genera examined in this study. Phylogenetic analysis of the behavioural data suggests that specialisations in nephiline building behaviour and web architecture did not evolve concurrently, and that some preceded the female giantism (not male dwarfism) for which nephiline spiders are well-known. Cladistic analysis of 60 characters supports the monophyly of both Tetragnathidae and Tetragnathinae. New data from spinneret silk gland spigots, combined with other morphological and behavioural characters, provide the first concrete evidence that 'metine' genera, occasionally regarded as either a distinct family or subfamily, are a paraphyletic assemblage.

No abstract

Summary 1.Frequency of singletons -species represented by single individuals -is anomalously high in most large tropical arthropod surveys (average, 32%). 2. We sampled 5965 adult spiders of 352 species (29% singletons) from 1 ha of lowland tropical moist forest in Guyana. 3. Four common hypotheses (small body size, male-biased sex ratio, cryptic habits, clumped distributions) failed to explain singleton frequency. Singletons are larger than other species, not gender-biased, share no particular lifestyle, and are not clumped at 0·25-1 ha scales. 4. Monte Carlo simulation of the best-fit lognormal community shows that the observed data fit a random sample from a community of ~700 species and 1-2 million individuals, implying approximately 4% true singleton frequency. 5. Undersampling causes systematic negative bias of species richness, and should be the default null hypothesis for singleton frequencies. 6. Drastically greater sampling intensity in tropical arthropod inventory studies is required to yield realistic species richness estimates. 7. The lognormal distribution deserves greater consideration as a richness estimator when undersampling bias is severe.

The Pantropical spider clade Nephilidae is famous for its extreme sexual size dimorphism, for constructing the largest orb-webs known, and for unusual sexual behaviors, which include emasculation and extreme polygamy. We synthesize the available data for the genera Nephila, Nephilengys, Herennia and Clitaetra to produce the first species level phylogeny of the family. We score 231 characters (197 morphological, 34 behavioral) for 61 taxa: 32 of the 37 known nephilid species plus two Phonognatha and one Deliochus species, 10 tetragnathid outgroups, nine araneids, and one genus each of Nesticidae, Theridiidae, Theridiosomatidae, Linyphiidae, Pimoidae, Uloboridae and Deinopidae. Four most parsimonious trees resulted, among which successive weighting preferred one ingroup topology. Neither an analysis of an alternative data set based on different morphological interpretations, nor separate analyses of morphology and behavior are superior to the total evidence analysis, which we therefore propose as the working hypothesis of nephilid relationships, and the basis for classification. Ingroup generic relationships are (Clitaetra (Herennia (Nephila, Nephilengys))). Deliochus and Phonognatha group with Araneidae rather than Nephilidae. Nephilidae is sister to all other araneoids (contra most recent literature). Ethological data, although difficult to obtain and thus frequently missing for rare taxa, are phylogenetically informative. We explore the evolution of selected morphological and behavioral characters, discuss and redefine the homology of palpal sclerites, disprove semientelegyny in spiders, trace the newly interpreted evolution of the orb web, and show that nephilid genital morphologies coevolve with sexual behaviors and extreme sexual size dimorphism. Phylogenetic interpretations of behavior suggest new insights into spider biology and avenues for future research.Ó The Willi Hennig Society 2007.Discovery of behavioral homologies has importance for biology and other human endeavors far beyond simply adding characters for phylogenetic analyses. Greene (1994) Golden orb-weaving spiders (Nephila) and hermit spiders (Nephilengys) are among the most prominent and most researched tropical arachnids (reviewed in Kuntner, 2005Kuntner, , 2006Kuntner, , 2007aHarvey et al., 2007). They are famous for extreme sexual size dimorphism in which males are many times smaller than the giant females

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 ¼ 904, CI ¼ 0.23, RI ¼ 0.58; uninformative characters excluded: L ¼ 900, CI ¼ 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.