Fernando Álvarez-Padilla

A Protocol For Digesting Internal Soft Tissues And Mounting Spiders For Scanning Electron Microscopy

Abstract We describe a simple protocol for digesting the internal soft tissues of spiders using an enzyme complex known as pancreatin. This technique is preferred over digestions with caustic agents because it better preserves the cuticle surface, allowing its study by means of scanning electron or transmitted light microscopy. In addition, we describe a technique for mounting spider body parts for scanning electron microscopy using an acryloid polymer.

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.

Phylogenetic relationships of the spider family Tetragnathidae (Araneae, Araneoidea) based on morphological and DNA sequence data

The monophyly of Tetragnathidae including the species composition of the family (e.g., Are Nephila and their relatives part of this lineage?), the phylogenetic relationships of its various lineages, and the exact placement of Tetragnathidae within Araneoidea have been three recalcitrant problems in spider systematics. Most studies on tetragnathid phylogeny have focused on morphological and behavioral data, but little molecular work has been published to date. To address these issues we combine previous morphological and behavioral data with novel molecular data including nuclear ribosomal RNA genes 18S and 28S, mitochondrial ribosomal RNA genes 12S and 16S and protein‐coding genes from the mitochondrion [cytochrome c oxidase subunit I (COI)] and from the nucleus (histone H3), totaling ca. 6.3 kb of sequence data per taxon. These data were analyzed using direct optimization and static homology using both parsimony and Bayesian methods. Our results indicate monophyly of Tetragnathidae, Tetragnathinae, Leucauginae, the “Nanometa clade” and the subfamily Metainae, which, with the exception of the later subfamily, received high nodal support. Morphological synapomorphies that support these clades are also discussed. The position of tetragnathids with respect to the rest of the araneoid spiders remains largely unresolved but tetragnathids and nephilids were never recovered as sister taxa. The combined dataset suggests that Nephilidae is sister to Araneidae; furthermore, the sister group of Nephila is the clade composed by Herennia plus Nephilengys and this pattern has clear implications for understanding the comparative biology of the group. Tetragnathidae is most likely sister to some members of the “reduced piriform clade” and nephilids constitute the most‐basal lineage of araneids.

Tarsal organ morphology and the phylogeny of goblin spiders (Araneae, Oonopidae), with notes on basal genera

ABSTRACT Based on a survey of a wide variety of oonopid genera and outgroups, we hypothesize new synapomorphies uniting the Oonopidae (minus the South African genus Calculus Purcell, which is transferred to the Orsolobidae). The groundplan of the tarsal organ in Oonopidae is hypothesized to be an exposed organ with a distinctive, longitudinal ridge originating from the proximal end of the organ, and a serially dimorphic pattern of 4-4-3-3 raised receptors on legs I–IV, respectively. Such organs typify the diverse, basal, and ancient genus Orchestina Simon. Several other genera whose members resemble Orchestina in retaining two plesiomorphic features (an H-shaped, transverse eye arrangement and a heavily sclerotized, thick-walled sperm duct within the male palp) are united by having tarsal organs that are partly (in the case of Cortestina Knoflach) or fully capsulate (in the case of Sulsula Simon, Xiombarg Brignoli, and Unicorn Platnick and Brescovit). The remaining oonopids are united by the loss of the heavily sclerotized palpal sperm duct, presumably reflecting a significant transformation in palpal mechanics. Within that large assemblage, a 4-4-3-3 tarsal organ receptor pattern and an H-shaped eye arrangement seem to be retained only in the New Zealand genus Kapitia Forster; the remaining genera are apparently united by a reduction in the tarsal organ pattern to 3-3-2-2 raised receptors on legs I–IV and by the acquisition of a clumped eye arrangement. Three subfamilies of oonopids are recognized: Orchestininae Chamberlin and Ivie (containing only Orchestina; Ferchestina Saaristo and Marusik is placed as a junior synonym of Orchestina), Sulsulinae, new subfamily (containing Sulsula, Xiombarg, Unicorn, and Cortestina), and Oonopinae Simon (containing all the remaining genera, including those previously placed in the Gamasomorphinae). The type species of Sulsula and Kapitia, S. pauper (O. P.-Cambridge) and K. obscura Forster, are redescribed, and the female of S. pauper is described for the first time. A new sulsuline genus, Dalmasula, is established for Sulsula parvimana Simon and four new species from Namibia and South Africa.

First Records of Extant Hispaniolan Spiders of the Families Mysmenidae, Symphytognathidae, and Ochyroceratidae (Araneae), Including a New Species of Ochyrocera

Abstract A new species of ochyroceratid spider, Ochyrocera cachote, n.sp., is described and its unique web architecture is documented. This is the first record of Ochyroceratidae for the extant fauna of Hispaniola. Additional new family records include Symphytognathidae (Patu sp. and Symphytognatha sp.) and Mysmenidae (Microdipoena sp.), with the latter family having been previously recorded from the fossil amber fauna. This makes a new total of 46 spider families recorded from the extant Hispaniolan fauna, but on the whole the islands araneofauna remains poorly known and warrants further investigation.

Finding an upper limit for gap costs in direct optimization parsimony

Exploring a large number of parameter sets in sensitivity analyses of direct optimization parsimony can be costly in terms of time and computing resources, and there is little a priori guidance available for reasonable limits to these search parameters. For this reason, we sought a general‐purpose upper limit for gap costs in the direct optimization program POY to streamline this process. To test the performance of POY as gap costs increase, we simulated data onto a pre‐set topology using a GTR + I + G model modified to include gaps by adding them according to a negative‐binomial model. Gaps were then removed and the data were analysed in POY at increasing gap costs. Increasing gap costs consistently resulted in reduced phylogenetic accuracy across trees of different relative branch lengths. Decoupling gap insertion and gap extension costs recovered a fraction of the accuracy lost by having both high gap insertion and gap extension costs, but only in trees with long internal nodes. To determine whether loss of phylogenetic accuracy was node‐specific, we designed a small dataset with a constrained node, where all possible combinations of cost substitution and different percentages of gap versus nucleotide changes were explored. These analyses showed that the effects of gap insertion and extension are node‐specific, and the minimum threshold for convergence on gap‐supported nodes is similar to the threshold for accuracy loss found in the larger simulated datasets. Subsequent analyses of empirical data revealed that a similar pattern of loss with gap cost increase can occur with ribosomal genes (18S, 28S, 16S and 12S) but this pattern was not seen in the intron data (myoglobin II) examined. In conjunction with previously published congruence‐based studies, the results suggest that POY sensitivity analyses can be streamlined and made more accurate if gap insertion and extension costs follow, as a guideline, a limit of four times the highest base‐transformation cost.

SYSTEMATICS OF THE AFRO-MACARONESIAN SPIDER GENUS SANCUS (ARANEAE, TETRAGNATHIDAE)

Abstract We review the systematics of the tetragnathid spider genus Sancus Tullgren, hitherto known from a single species from Kilimanjaro. The type species Sancus bilineatus Tullgren is redescribed and diagnosed from the only other known species, S. acoreensis (Wunderlich) new combination. Leucognatha Wunderlich is a junior synonym of Sancus, which thus eliminates two monotypic tetragnathid genera. A phylogenetic analysis of 15 tetragnathid and eight outgroup genera confirms the monophyly of Sancus and places it precisely in Tetragnathidae. We discuss the phylogenetic relationships among tetragnathid genera and the peculiar biogeography of Sancus, now known from east African mountains (Kilimanjaro and Mt. Kenya) and from the Azores in the northeastern Atlantic.

Noideattella and Tolegnaro, Two New Genera of Goblin Spiders from Madagascar, with Comments on the Gamasomorphoid and Silhouettelloid Oonopids (Araneae, Oonopidae)

ABSTRACT Two new genera of goblin spiders from Madagascar, Noideattella, new genus, and Tolegnaro, new genus, are described with 11 and two species respectively. Noideattella includes N. assumptia, new combination (transferred from Silhouettella), and 10 new species: N. amboa, N. famafa, N. fantara, N. farihy, N. gamela, N. lakana, N. mamba, N. saka, N. tany, and N. tsiba. Tolegnaro includes two new species: T. sagani and T. kepleri. A phylogenetic data matrix of 436 terminals and 341 morphological characters was extracted from the Goblin Spider Planetary Biodiversity Inventory (PBI) descriptive database. The monophyly of Noideattella and Tolegnaro was tested in a phylogenetic analysis of this matrix. In this analysis other oonopid genera recently revised were also recovered as monophyletic and with high support values. A key for all species described here is provided. Noideattella species can be differentiated by having the pars cephalica strongly elevated in lateral view, forming a posterior cone, tibia and metatarsi with spines, and abdomen completely covered by scuta. Tolegnaro species in addition present plumose seta around the pedicel area.

On the Phylogenetic Placement of the Spider Genus Atimiosa Simon, 1895, and the Circumscription of Dolichognatha O.P.-Cambridge, 1869 (Tetragnathidae, Araneae)

Abstract The genus Atimiosa Simon, 1895, is a junior synonym of Dolichognatha O. P.-Cambridge, 1869. This synonymy is strongly supported by cladistic analyses of morphological characters and examination of types of all known Atimiosa species. Two new combinations resulted from this nomenclatural change, Dolichognatha comorensis (Schmidt and Krause, 1993), new combination, and Dolichognatha quinquemucronata (Simon, 1895), new combination. New illustrations and photographs of these two species and of the poorly known Dolichognatha longiceps (Thorell, 1895) are provided. We also describe for the first time the web architecture of D. longiceps.