Gustavo Hormiga

Gustavo Hormiga
George Washington University | GW · Department of Biological Sciences

Ph.D. 1995. Univ. Maryland at College Park

About

155
Publications
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5,084
Citations
Additional affiliations
January 1996 - October 2015
George Washington University
Position
  • Professor (Full)

Publications

Publications (155)
Article
A prominent question in animal research is how the evolution of morphology and ecology interact in the generation of phenotypic diversity. Spiders are some of the most abundant arthropod predators in terrestrial ecosystems and exhibit a diversity of foraging styles. It remains unclear how spider body size and proportions relate to foraging style, a...
Article
Full-text available
Deciphering the evolutionary relationships of Chelicerata (arachnids, horseshoe crabs, and allied taxa) has proven notoriously difficult, due to their ancient rapid radiation and the incidence of elevated evolutionary rates in several lineages. While conflicting hypotheses prevail in morphological and molecular datasets alike, the monophyly of Arac...
Article
Full-text available
Spiders are unique in having a dual respiratory system with book lungs and tracheae, and most araneomorph spiders breathe simultaneously via book lungs and tracheae, or tracheae alone. The respiratory organs of spiders are diverse but relatively conserved within families. The small araneoid spiders of the symphytognathoid clade exhibit a remarkably...
Article
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 Pimoida...
Preprint
Full-text available
Deciphering the evolutionary relationships of Chelicerata (arachnids, horseshoe crabs, and allied taxa) has proven notoriously difficult, due to their ancient rapid radiation and the incidence of elevated evolutionary rates in several lineages. While conflicting hypotheses prevail in morphological and molecular datasets alike, the monophyly of Arac...
Article
Full-text available
Zootaxa published more than a thousand papers on Araneae from 2002 to the present, including descriptions of 3,833 new spider species and 177 new genera. Here we summarise the key contributions of Zootaxa to our current knowledge of global spider diversity. We provide a historical account of the researchers that have actively participated as editor...
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Morphological and molecular evidence support the taxonomic separation of the medically important Neotropical spiders Phoneutria depilata (Strand, 1909) and P. boliviensis (F.O. Pickard-Cambridge, 1897) (Araneae, Ctenidae). Abstract The species of the genus Phoneutria (Ctenidae), also called banana spiders, are considered amongst the most venomous s...
Article
Spiders (Araneae) make up a remarkably diverse lineage of predators that have successfully colonized most terrestrial ecosystems. All spiders produce silk, and many species use it to build capture webs with an extraordinary diversity of forms. Spider diversity is distributed in a highly uneven fashion across lineages. This strong imbalance in speci...
Article
Hickmania troglodytes is an emblematic cave spider representing a monotypic cribellate spider genus. This is the only Australian lineage of Austrochilidae while the other members of the family are found in southern South America. In addition to being the largest spider in Tasmania, Hickmania is an oddity in Austrochilidae because this is the only l...
Article
The Opiliones family Neopilionidae is restricted to the terranes of the former temperate Gondwana: South America, Africa, Australia, New Caledonia and New Zealand. Despite decades of morphological study of this unique fauna, it has been difficult reconciling the classic species of the group (some described over a century ago) with recent cladistic...
Article
The tetragnathid genus Leucauge includes some of the most common orb-weaving spiders in the tropics. Although some species in this genus have attained relevance as model systems for several aspects of spider biology, our understanding of the generic diversity and evolutionary relationships among the species is poor. In this study we present the fir...
Article
The spider genus Nemoscolus Simon, 1895 (Araneidae) has been neglected taxonomically despite the unique retreat that several species construct in their horizontal orb-webs, composed of pebbles and other detritus. The distribution of Nemoscolus is poorly known and the genus includes species from Africa and Europe. Nemoscolus is placed in Simon's Cyc...
Article
High throughput sequencing and phylogenomic analyses focusing on relationships among spiders have both reinforced and upturned long‐standing hypotheses. Likewise, the evolution of spider webs—perhaps their most emblematic attribute—is being understood in new ways. With a matrix including 272 spider species and close arachnid relatives, we analyze a...
Article
We report on the colonization and diversification of linyphiid spiders in the Pacific oceanic archipelago of Juan Fernandez. About 50 spider species occur naturally in these islands, most of them endemic and about half of them are linyphiids. Linyphiidae includes no fewer than 15 species of Laminacauda and three of Neomaso (with several additional...
Article
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Genome-scale data sets are converging on robust, stable phylogenetic hypotheses for many lineages; however, some nodes have shown disagreement across classes of data. We use spiders (Araneae) as a system to identify the causes of incongruence in phylogenetic signal between three classes of data: exons (as in phylotranscriptomics), non-coding region...
Article
The spider family Tetragnathidae Menge is a cosmopolitan, relatively well-studied spider clade with some members readily identifiable by their elongate chelicerae and/or their horizontal orb webs. It has four recognized subfamilies—Tetragnathinae, Metainae, Leucauginae, and the Australasian endemic Nanometinae—although many genera remain unassigned...
Article
Mimetidae is one of the three families within Araneoidea whose members do not spin foraging webs, but are unique in displaying a complex prey-capture behaviour known as aggressive mimicry. Mimetids are distributed worldwide and are most diverse in the tropics of Central and South America. Here we provide a comprehensive phylogeny of pirate spiders...
Article
Mite harvestmen of the family Neogoveidae have a tropical trans-Atlantic distribution with representatives in equatorial West Africa and the Neotropics, specifically in the south-east region of the USA and in northern South America, being conspicuously absent from Central America. We provide a comprehensive molecular phylogeny of the family includi...
Article
This paper addresses the systematics of the New Zealand spiders of the family Malkaridae. Malkarids are small araneoid spiders that live primarily in the leaf litter and mosses of temperate and tropical wet forests in Australia and New Zealand, with the exception of a single species in southern South America and another in New Caledonia. We treat t...
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Sexual size dimorphism in orb-weaving spiders is a relatively well-studied phenomenon, and numerous works have documented evolutionary variation in interspecific size and degree of dimorphism. To date, these studies have been largely limited to assessing the evolution of a single or few linear measurements correlated with body size. While the descr...
Article
Phylogenomic methods have proven useful for resolving deep nodes and recalcitrant groups in the spider tree of life. Across arachnids, transcriptomic approaches may generate thousands of loci, and target‐capture methods, using the previously designed arachnid‐specific probe‐set, can target a maximum of about 1,000 loci. Here, we develop a specializ...
Article
The monotypic family Trogloraptoridae was only recently described from caves and old‐growth forest of Oregon and California (Western USA). These enigmatic spiders are characterized by striking raptorial claws, and based on their spinneret morphology, a close relationship to dysderoid spiders, a large clade within Synspermiata, was suggested. Here,...
Article
We address some of the taxonomic and classification changes proposed by Kuntner et al. (in press) in a comparative study on the evolution of sexual size dimorphism in nephiline spiders. Their proposal to re-circumscribe araneids and to rank the subfamily Nephilinae is fundamentally flawed as it renders the family Araneidae paraphyletic. We discuss...
Article
The genus Chorizopes (Araneae, Araneidae) includes over two dozen species of webless araneids found mainly in the Indomalayan region. They are characterised by a distinctive bulbous carapace and a specialised foraging behaviour: preying on other orb-weavers. Chorizopes casictones, sp. nov. (Araneae, Araneidae) is described based on specimens collec...
Article
We revise and monograph the Australasian clade of the araneid subfamily Zygiellinae F.O. Pickard-Cambridge. Several members of this clade construct conspicuous leaf retreats at the hub of their webs. We gathered and analyzed a matrix of 95 taxa of zygiellines and close relatives with sequence data from six genetic markers (12S rRNA, 16S rRNA, 18S r...
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Mite harvestmen of the family Neogoveidae have a tropical trans-Atlantic distribution with representatives in equatorial West Africa and the Neotropics, being conspicuously absent from Central America. We provide a comprehensive molecular phylogeny of Neogoveidae including representatives of all genera but the monotypic Tucanogovea Karaman, 2013, a...
Article
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The Convention on Biological Diversity (CBD) commits its 196 nation parties to conserve biological diversity, use its components sustainably, and share fairly and equitably the benefits from the utilization of genetic resources. The last of these objectives was further codified in the Convention's Nagoya Protocol (NP), which came into effect in 201...
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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 grad...
Article
The orb-weaving spider family Araneidae is extremely diverse (> 3,100 spp.) and its members can be charismatic terrestrial arthropods, many of them recognizable by their iconic orbicular snare web, such as the common garden spiders. Despite considerable effort to better understand their backbone relationships based on multiple sources of data (morp...
Article
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...
Article
The orchard spider, Leucauge venusta (Walckenaer, 1841) is one of the most common and abundant orb-weavers in North America. This species has a broad geographic distribution extending across tropical and temperate regions of the Americas from Canada to Brazil. Guided by a preliminary observation of the barcode gap between sequences from specimens o...
Article
Despite numerous phylogenetic analyses of the orb-weaving spider family Tetragnathidae, several relationships from the subfamily to species level are tenuous or unclear. One such example regards the validity and composition of the tetragnathid subfamily Metainae, which historically has mixed support and limited taxon sampling. Sequences for six gen...
Article
We report for the first time the occurrence of pimoids (Araneoidea, Pimoidae) in Taiwan, describe Putaoa seediq new species, revise the genus diagnosis accordingly, and illustrate for the first time the web architecture of Putaoa based on field photographs. Males of Putaoa species differ from other pimoids in having distinctively large macrosetae o...
Article
A new species of the Australian genus Pinkfloydia, P. rixi new species, is described and illustrated. This new tetragnathid species is known only from the type locality in the eastern part of New South Wales, more than 3,200 km away from the distribution range of it sister species from Western Australia, P. harveii Dimitrov & Hormiga, 2011. The nat...
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Pimoa delphinica Mammola, Hormiga & Isaia, 2016 is a troglophile araneoid spider endemic of the high Varaita valley (Western Alps, Province of Cuneo, NW Italy). In spite of relatively intense field research and examination of museum collections, the species is restricted to ten localities, thus showing a reduced extent of occurrence (EOO; 26 km) an...
Data
Extent of Occurrence of Pimoa delphinica
Article
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...
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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....
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The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009;...
Data
This plot is not part of the published stance but derives from it. The plot shows the number of authors by geographic region (courtesy of Dr. Diego Astua).
Article
We investigate the phylogeny of “pirate spiders” (Mimetidae), a family of araneophagic spiders known for their use of aggressive mimicry as a foraging strategy, but poorly understood phylogenetically. Relationships are inferred by including molecular data from six loci for 92 mimetid terminals spanning four genera, and 119 outgroups representing 12...
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We test the limits of the spider superfamily Araneoidea and reconstruct its interfamilial relationships using standard molecular markers. The taxon sample (363 terminals) comprises for the first time representatives of all araneoid families, including the first molecular data of the family Synaphridae. We use the resulting phylogenetic framework to...
Article
Current sequencing technologies are making available unprecedented amounts of genetic data for a large variety of species including non-model organisms. Although many phylogenomic surveys spend considerable time finding orthologs from the wealth of sequence data, these results do not transcend the original study and after being processed for specif...
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Despite having been utilized for over 250 years, Linnaean ranks are periodically dismissed by some systematists and evolutionary biologists. Here, we discuss recent criticisms and point out that they are often the result of a misunderstanding of both the meaning and the intent of such ranks. Although arbitrary in some cases, ranks contain meaningfu...
Article
We revise the Neotropical spider genus Gelanor Thorell, 1869 (Mimetidae). Gelanor is distributed from northeast Mexico to southern Uruguay, from sea level to 1,600 m. We describe five new species of Gelanor and report eleven new synonymies. Gelanor is here circumscribed to include ten species: Gelanor fortuna new species, Gelanor juruti new species...
Article
The tetragnathid genus Chrysometa Simon, 1894 includes 138 species found in the Americas, ranging from the Caribbean to Chile (World Spider Catalog 2015). This genus was revised by Levi (1986), with more recent publications adding to the genus (Álvarez-Padilla 2007, Nogueira et al. 2011, Simó et al., in press). Following Álvarez-Padilla & Hormiga (...
Article
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 sho...
Article
This paper provides the first comprehensive comparative morphological study of symphytognathoid spiders, with an emphasis on the family Mysmenidae. Hypotheses of primary homology, particularly at the level of male genitalia, are proposed for a total of 65 taxa (42 mysmenids), compiled into a morphological data set of more than 350 characters. Male...
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The monotypic linyphiid genus Lomaita Bryant 1948 is redescribed. We present an updated description of the male of L. darlingtoni, the first description of the female and data on its natural history and distribution in the Dominican Republic. We provide a hypothesis on the phylogenetic placement of Lomaita based on cladistic analyses of morphologic...
Article
Chelicerata represents one of the oldest groups of arthropods, with a fossil record extending to the Cambrian, and is sister 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 chelicer...
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Female genital morphology of secondarily haplogyne spiders has been poorly studied, hampering the analysis of its possible phylogenetic significance. We conduct a comparative morphological study of 12 species of the secondarily haplogyne spider genus Glenognatha Simon, 1887 using scanning electron microscopy. Representatives of the closely related...
Article
Spiders constitute one of the most successful clades of terrestrial predators [1]. Their extraordinary diversity, paralleled only by some insects and mites [2], is often attributed to the use of silk, and, in one of the largest lineages, to stereotyped behaviors for building foraging webs of remarkable biomechanical properties [1]. However, our und...
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The family Pimoidae is a small lineage of araneoid spiders distributed in Western North America, Southern Europe and Asia. Currently four genera and 37 extant species have been described (Platnick 2014). Pimoidae are represented in North America by 14 species classified in the genera, Pimoa Chamberlin & Ivie, 1943, and Nanoa Hormiga, Buckle & Schar...
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Laetesia raveni n. sp. (Araneae, Linyphiidae), is described based on specimens collected in New South Wales and Queensland (Australia). This new linyphiid species is of bright green colour, and it seems to have a preference to build its webs almost exclusively on two plant species, namely Calamus muelleri Wendland (Arecaceae) and Solanum inaequilat...
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Very few studies have addressed the linyphiid fauna of Australia. Most of the existing taxonomic work on Australian linyphiids consists of isolated species descriptions (e.g., Rainbow 1912) or at most are based on small number of species also described outside a revisionary context (e.g., Wunderlich 1976) (but see van Helsdingen 1972 for a revision...
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The orb-weaving spiders (Orbiculariae) comprise more than 25% of the approximately 44,000 known living spider species and produce a remarkable variety of webs. The wheel-shaped orb web is primitive to this clade, but most Orbiculariae make webs hardly recognizable as orbs. Orb-weavers date at least to the Jurassic. With no evidence for convergence...
Article
The Opopaea fauna of Madagascar is documented for the first time. There are 27 species of Opopaea on the island of which 26 are newly described here and 25 are apparently endemic to Madagascar: Opopaea andranomay, n. sp., O. ankarafantsika, n. sp., O. ankarana, n. sp., O. antsalova, n. sp., O. andringitra, n. sp., O. antsiranana, n. sp., O. bemariv...
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The refugial speciation model, or 'species pump', is widely accepted in the context of tropical biogeography and has been advocated as an explanation for present species distributions in tropical Western and Central Africa. In order to test this hypothesis, a phylogeny of the cryptic arachnid order Ricinulei, based on four nuclear and mitochondrial...
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Abstract. Male secondary genitalia (pedipalps) are useful characters for species discrimination in most spider families. Although efforts have been made to establish pedipalp sclerite homologies, there are still many inconsistencies in their use. The majority of the morphological characters used to reconstruct the linyphiid phylogeny address male g...
Article
The araneid genus Exechocentrus Simon, 1889 and its type species Exechocentrus lancearius were originally described based on a single female specimen from Madagascar, which was missing the abdomen. The first complete adult specimen, a female, of Excechocentrus lancearius was collected in 2000. A second adult female of Excechocentrus sp. was discove...
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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 hypothe sized to be an exposed organ with a distinctive, longitudinal ridge origina...