Lara Lopardo

Phylogenetic placement of the Tasmanian spider Acrobleps hygrophilus (Araneae, Anapidae) with comments on the evolution of the capture web in Araneoidea

This paper studies the family‐level phylogenetic placement of the conflicting Tasmanian spider genus Acrobleps using both morphological and behavioral data. We also provide a formal taxonomic revision of Acrobleps, including information on its web architecture and natural history, as well as detailed morphological information for A. hygrophilus, its only species. Acrobleps hygrophilus lacks the typical mysmenid features. Furthermore A. hygrophilus does have all typical and diagnostic characteristics of Anapidae, except for the labral spur. We also discuss two noteworthy morphological features of Acrobleps: the pore bearing depressions of the carapace and the granulated cuticle of the spinnerets. Variation in the latter feature might provide a useful phylogenetic character. Based on the results of cladistic analyses we propose the transfer of Acrobleps from the Mysmenidae to its original placement within the Anapidae. We also propose a new lineage, informally labeled as the “clawless female clade”, which includes synaphrids, cyatholipids and “symphytognathoids.” The secondary absence of the female palpal claw provides support for the “clawless female clade.” We discuss the evolution of the orb web within anapids and other symphytognathoids based on the results of our cladistic analyses. The identical bi‐dimensional webs of the anapid Elanapis and of symphytognathids have evolved independently. Finally, we comment on the implications of one of our analyses regarding araneoid web evolution. We conclude that the taxon sample included in the previous orbicularian data matrix (modified and used in this study) is adequate to test the phylogenetic placement of Acrobleps in Anapidae but insufficient to significantly assess web evolution within Araneoidea.

Tangled in a sparse spider web: single origin of orb weavers and their spinning work unravelled by denser taxonomic sampling

In order to study the tempo and the mode of spider orb web evolution and diversification, we conducted a phylogenetic analysis using six genetic markers along with a comprehensive taxon sample. The present analyses are the first to recover the monophyly of orb-weaving spiders based solely on DNA sequence data and an extensive taxon sample. We present the first dated orb weaver phylogeny. Our results suggest that orb weavers appeared by the Middle Triassic and underwent a rapid diversification during the end of the Triassic and Early Jurassic. By the second half of the Jurassic, most of the extant orb-weaving families and web designs were already present. The processes that may have given origin to this diversification of lineages and web architectures are discussed. A combination of biotic factors, such as key innovations in web design and silk composition, as well as abiotic environmental changes, may have played important roles in the diversification of orb weavers. Our analyses also show that increased taxon sampling density in both ingroups and outgroups greatly improves phylogenetic accuracy even when extensive data are missing. This effect is particularly important when addition of character data improves gene overlap.

The spider tree of life: phylogeny of Araneae based on target‐gene analyses from an extensive taxon sampling

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 redefined to include five subfamilies: Amphinectinae, with Amphinecta, Mamoea, Maniho, Paramamoea and Rangitata (transferred from Amphinectidae); Ischaleinae, with Bakala and Manjala (transferred from Amaurobiidae) and Ischalea (transferred from Stiphidiidae); Metaltellinae, with Austmusia, Buyina, Calacadia, Cunnawarra, Jalkaraburra, Keera, Magua, Metaltella, Penaoola and Quemusia; Porteriinae (new rank), with Baiami, Cambridgea, Corasoides and Nanocambridgea (transferred from Stiphidiidae); and Desinae, with Desis, and provisionally Poaka (transferred from Amaurobiidae) and Barahna (transferred from Stiphidiidae). Argyroneta is transferred from Cybaeidae to Dictynidae. Cicurina is transferred from Dictynidae to Hahniidae. The genera Neoramia (from Agelenidae) and Aorangia, Marplesia and Neolana (from Amphinectidae) are transferred to Stiphidiidae. The family Toxopidae (restored status) includes two subfamilies: Myroinae, with Gasparia, Gohia, Hulua, Neomyro, Myro, Ommatauxesis and Otagoa (transferred from Desidae); and Toxopinae, with Midgee and Jamara, formerly Midgeeinae, new syn. (transferred from Amaurobiidae) and Hapona, Laestrygones, Lamina, Toxops and Toxopsoides (transferred from Desidae). We obtain a monophyletic Oval Calamistrum clade and Dionycha; Sparassidae, however, are not dionychans, but probably the sister group of those two clades. The composition of the Oval Calamistrum clade is confirmed (including Zoropsidae, Udubidae, Ctenidae, Oxyopidae, Senoculidae, Pisauridae, Trechaleidae, Lycosidae, Psechridae and Thomisidae), affirming previous findings on the uncertain relationships of the “ctenids” Ancylometes and Cupiennius, although a core group of Ctenidae are well supported. Our data were ambiguous as to the monophyly of Oxyopidae. In Dionycha, we found a first split of core Prodidomidae, excluding the Australian Molycriinae, which fall distantly from core prodidomids, among gnaphosoids. The rest of the dionychans form two main groups, Dionycha part A and part B. The former includes much of the Oblique Median Tapetum clade (Trochanteriidae, Gnaphosidae, Gallieniellidae, Phrurolithidae, Trachelidae, Gnaphosidae, Ammoxenidae, Lamponidae and the Molycriinae), and also Anyphaenidae and Clubionidae. Orthobula is transferred from Phrurolithidae to Trachelidae. Our data did not allow for complete resolution for the gnaphosoid families. Dionycha part B includes the families Salticidae, Eutichuridae, Miturgidae, Philodromidae, Viridasiidae, Selenopidae, Corinnidae and Xenoctenidae (new fam., including Xenoctenus, Paravulsor and Odo, transferred from Miturgidae, as well as Incasoctenus from Ctenidae). We confirm the inclusion of Zora (formerly Zoridae) within Miturgidae.

Morphology to the rescue: molecular data and the signal of morphological characters in combined phylogenetic analyses—a case study from mysmenid spiders (Araneae, Mysmenidae), with comments on the evolution of web architecture

The limits and the interfamilial relationships of the minute orb‐weaving symphytognathoid spiders have remained contentious and poorly understood. The circumscription and diagnosis of the symphytognathoid family Mysmenidae have always been elusive, and its monophyly has never been thoroughly tested. We combine sequence data from six genes with a morphological dataset in a total‐evidence phylogenetic analysis (ca. 6100 characters, 109 taxa: 74 mysmenids), and explore the phylogenetic signal of the combined dataset, individual genes, and gene combinations with different parsimony methods and model‐based approaches. Several support values and parameter‐sensitivity schemes are explored to assess stability of clades. Mysmenidae monophyly is supported by ca. 20 morphological and ca. 420 molecular synapomorphies. Mysmenidae is monophyletic under all combined analyses that include morphology. Almost no gene or gene combination supports Mysmenidae monophyly. Symphytognathoids are delimited to include: (Theridiosomatidae (Mysmenidae (Synaphridae (Anapidae + Symphytognathidae)))). Micropholcommatids are a lineage nested within the anapid clade and thus are synonymized with Anapidae (Micropholcommatinae New Rank). We provide morphological diagnoses for all symphytognathoid families and discuss the behavioural evolutionary implications of our hypotheses of relationships. The planar orb web evolved independently twice from three‐dimensional webs. The orb web was modified into sheet or cobwebs three times independently. The spherical mysmenine web has a single origin. Kleptoparasitism evolved once in mysmenids. We comment on the discrepancies and lack of resolving power of the molecular datasets relative to the morphological signal, and discuss the relevance of morphology in inferring the total‐evidence phylogenetic pattern of relationships.

On the Synaphrid Spider Cepheia longiseta (Simon 1881) (Araneae, Synaphridae)

Abstract We redescribe the monotypic spider genus Cepheia and provide detailed morphological information on its type species, Cepheia longiseta. We provide the first exhaustive diagnosis for the genus, including for the first time detailed information about its external morphology as well as its tracheal system. Some morphological features previously proposed as synapomorphies for the Synaphridae are also present in Cepheia, which corroborates some of the diagnostic characters of the family. We also propose new synapomorphies for Synaphridae.

The Combing of Cribellar Silk by the Prithine Misionella Mendensis, with Notes on Other Filistatid Spiders (Araneae: Filistatidae)

Abstract We present the first observations of the combing and attaching behavior in the subfamily Prithinae (Filistatidae), taken from Misionella mendensis. We compare its web architecture with that of other prithines (Pritha nana and Pikelinia sp. from Chile) and filistatines (Kukulcania hibernalis and Filistata insidiatrix). The combing behavior of M. mendensis corresponds to the stereotyped type I combing behavior, as is known for other filistatids. However, M. mendensis attaches the cribellar segments in a unique way, splitting the cribellar segment longitudinally and pushing each half to the substrate, attaching the silk with the tarsi of both legs IV simultaneously. These stereotyped movements result in web units of a very characteristic structure. We report the same split attachment behavior in the prithine Pikelinia tambilloi. We scored these observations into a previous dataset for filistatid relationships. Because of the missing observations on attachment behavior in the North American basal genus Filistatinella, the sister group of all other prithines, the evolution of split cribellar strands is a potential synapomorphic characteristic for the Prithinae, or at least the subgroup excluding its basal taxon.

Spinneret Spigot Morphology in Synaphrid Spiders (Araneae, Synaphridae), with Comments on the Systematics of The Family and Description of A New Species of Synaphris Simon 1894 from Spain

Abstract We describe for the first time the spigot morphology of two synaphrid species (one of each of two synaphrid genera, Synaphris and Cepheia) as well as the morphology of the respiratory system of Synaphris. We also provide a taxonomic description of a new species of Synaphris from Spain, including detailed information about its morphology. This new species is known only from males, and it might belong to the so-called letourneuxi species group. Some morphological features proposed as synapomorphies for the genus Synaphris and/or the Synaphridae are questioned and discussed. Putative synapomorphies proposed here include a distinct constriction on the tarsus-metatarsus joints; a cheliceral keel ending in a strong promarginal cheliceral tooth; scarce number of maxillary setae; distal maxillary setae clavate; and a characteristic palpal morphology, comprising a distinctive tibial morphology, a modified cymbium with two separate areas, a palpal dorsal translucent expansion of the embolar base, a retrolateral paracymbium, a reduced furrow separating the major ampullate field from the piriform field, and the retention of at least one triad spigot in males. Refuted synapomorphies are the metatarsal subdistal anastomosed lyriform organ, the notched tibial trichobothrial base, and the tarsal pseudosegmentation. We also discuss the phylogenetic placement of the family, suggesting a close relationship to the araneoid Cyatholipidae.

Notes on Chilean Anapids and Their Webs

Abstract Orb webs of the Chilean anapid genera Crassanapis Platnick and Forster, Sheranapis Platnick and Forster, and Elanapis Platnick and Forster are described for the first time. Crassanapis and Sheranapis species spin a typical anapid web, with one to several radii above the orb- plane, going upward from the hub. Their webs are intraspecifically variable in size and architectural details. Sheranapis villarrica Platnick and Forster often constructs smaller webs close to the water surface of streams. The web of Elanapis aisen Platnick and Forster is two dimensional, without orb-plane threads, like typical webs of Symphytognathidae. The webs of Minanapis species are still unknown. Elanapis aisen has a protruding labrum, which supports its placement in Anapidae. The spinnerets of Elanapis aisen and Crassanapis chilensis are figured and described. The respiratory system of Elanapis aisen and Minanapis floris is described; all Chilean anapids examined so far have normal booklungs and four simple tracheae limited to the abdomen.