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Charles Griswold
Faculty
California Academy of Sciences
Entomology
San Francisco, CA
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| Archaeid spiders and their relatives (Araneae, Archaeidae): fossil placement, biogeography and evolution of the carapace morphology |
| Author(s) |
Hannah M Wood, Rosemary G Gillespie, Charles Griswold |
| Info |
Poster category:
Systematics |
| Abstract |
Molecular and morphological phylogenetic analyses are performed for living and extinct archaeids and for outgroup taxa representing 20 different spider families sampling throughout the Araneomorphae. Fossil archaeids are examined using X-ray Computed Tomography in order to understand phylogenetic placement of extinct lineages. Additionally, a molecular phylogenetic analysis of living archaeids is performed to elucidate relationships among extant species from Australia, Madagascar and South Africa. Biogeographic findings within different continents as well as between continents are discussed. The limits of the superfamily Palpimanoidea is examined. Furthermore, evolution of the carapace shape is examined from a phylogenetic context. |
| Evolution of a complex, novel structure, the trap-jaw mechanism, in spiders (Mecysmaucheniidae, Araneae) |
| Author(s) |
Hannah M Wood, Rosemary G Gillespie, Charles Griswold, Damian O Elias |
| Info |
Talk category:
Systematics |
| Abstract |
Trap jaw mechanisms have been described for the ant genus Odontomachus but is virtually unknown in one of the largest arthropod classes, the arachnids. The trap jaw mechanism has evolved twice independently in spiders, once in the family Pararchaeidae and once in the family Mecysmaucheniidae. The underlying structural mechanism for employing a trap jaw is unique in both families, with Mecysmaucheniids achieving the fastest known movements in arachnids. Within the mecysmaucheniids there is variation in both carapace and jaw shape and in the speeds of the jaws closing. Phylogenetic analyses of molecular data results in a mecysmaucheniid phylogeny that can be used to examine the evolution of this trait among lineages from New Zealand and Chile as well as to examine how this trait relates to distribution patterns. The biomechanical properties of this complex trait are examined among different lineages. |
| First steps towards a world monograph of the spider family Leptonetidae |
| Author(s) |
Joel Ledford, Carles Ribera, Byung-Woo Kim, Shuqiang Li, Charles Griswold |
| Info |
Poster category:
Systematics |
| Abstract |
Recent revisionary work has dramatically improved our understanding of species level diversity in the Leptonetidae, particularly in East Asia and North America. However, most leptonetid genera remain poorly characterized and phylogenetic relationships within the family are unexplored. As the rate of species discovery accelerates, there is a need to better define leptonetid genera in order to provide a taxonomic foundation for future studies and produce a scaffold for evaluating biogeographic and evolutionary patterns. Here we present the first assessment of leptonetid relationships based on a combination of molecular and morphological data including exemplars for most described genera worldwide. Morphological characters supporting major clades are discussed and an overview of leptonetid biogeography is provided. |
| On a fascinating new haplogyne spider from Southern Oregon caves |
| Author(s) |
Charles Griswold, Joel Ledford, Tracy Audisio |
| Info |
Talk category:
Systematics |
| Abstract |
A recent survey of caves in Southern Oregon has discovered a fascinating new haplogyne spider that cannot be confidently assigned to any known family. We provide an overview of this spider’s unique morphology and discuss alternatives for its phylogenetic placement. |
| The depths of divergence: A phylogenetic analysis of troglomorphic spiders in the genus Usofila (Araneae, Telemidae) |
| Author(s) |
Tracy Audisio, Joel Ledford, Charles Griswold |
| Info |
Talk category:
Systematics |
| Abstract |
Spiders in the genus Usofila thrive in cold, moist, dark microhabitats and are exapted for life in caves. Cave obligate, or troglobiotic, Usofila exhibit a suite of troglomorphic characters, however, species delimitation is problematic due to a high degree of morphological homogeneity. Although these taxa lack traditional diagnostic characters, they have evolved deep molecular divergence. The evolution of troglobionts can be explained either by the Climatic Relict Hypothesis (CRH) or by the Adaptive Shift Hypothesis (ASH). According to the CRH, troglobionts are relicts of a previously widespread fauna. A climatic shift occurred which pushed these species into caves. Alternatively, the ASH predicts a shift to the troglobiotic lifestyle prompted by resource availability. We used a combination of morphological and molecular data to assess species limits within Usofila and to test hypotheses for the evolution of troglobionts. Scanning electron microscopy and automontage were used to assess morphological variation, including both somatic and genitalic characters. Our molecular data is based on 28S rDNA and CO1 mtDNA from a sample of 51 individuals. Parsimony, Maximum Likelihood, and Bayesian analyses were used to estimate phylogenetic relationships and trait data were mapped on the resulting trees. Independent analysis of CO1 resulted in strong support for several terminal groups but was unable to resolve the deeper relationships. A concatenated analysis resolved the deeper relationships and suggested that there are eight new species of Usofila in California and that troglobionts have evolved independently on three occasions, which is consistent with the ASH hypothesis. |
| The goblin spiders (Oonopidae) of Madagascar: a morphological comparison of three genera. |
| Author(s) |
Darrell Ubick, Charles Griswold |
| Info |
Talk category:
Systematics |
| Abstract |
Madagascar has a rich oonopid fauna of over 100 species representing about 24 genera. Most of the species and about 60% of the genera are new and apparently endemic to the island. Here we report on three of these endemic genera.
Genus 1 includes species with large contiguous eyes (eye ring), prominent leg spines, reduced scutes in females and fused scutes in males, all characteristic of the Ischnothyreus complex. Genitalic characters of both the male and female suggest a close relationship to the Asian genus Camptoscaphiella.
Genus 2 resembles the many Malagasy species of the Silhouettella complex in several somatic characters, such as body form, eye arrangement, body sculpturing and leg spination, but differs in genitalic features. The male embolar region has few broad lobes, as opposed to several slender lobes in silhouettelloids, and the female genitalia lack a large oval receptaculum characteristic of silhouettelloids. Apart from that difference, the female genitalia are typically silhouettelloid and suggest that the genus belongs in this complex.
Genus 3 includes small spiders with reduced eyes and scutes, and with an unusual character combination. The genus resembles silhouettelloids in body form, leg spination and eye arrangement, but also ischnothyroids in that males have fused abdominal scutes. The female genitalia likewise include characteristics of both groups. The placement of this genus is speculated but remains unresolved.
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| Several new species of silhouettelloid goblin spiders of Madagascar (Araneae, Oonopidae). |
| Author(s) |
Fernando Alvarez-Padilla, Darrell Ubick, Charles Griswold |
| Info |
Poster category:
Systematics |
| Abstract |
Currently goblin spiders are subject to considerable taxonomic research by a large group of colleagues in many countries as part of the Planetary Biodiversity Inventory (PBI). The work presented here contributes to this effort to document and describe oonopid diversity world wide. We describe a total of nine species from Madagascar and the Seychelles documented with ca. 390 compound digital images and 670 scanning electron microscope pictures. These species represent two genera: Silhouettella Benoit, 1979 characterized by the absence of leg spines, eyes well developed occupying three quarters of the cephalothorax width and abdomen completely covered with scuta, and the new genus characterized by a gradual reduction of eyes, presence of leg spines and abdominal scuta. All species are new except Silhouettella curieusei the type of this genus which is only known from the Seychelles. The core of the taxonomic descriptions was done automatically by coding character observations to the PBI website using only a Internet browser and based mainly on the images mentioned above. The geographic distribution for all specimens was added to the PBI Database for Entering Collection Data (DEC) web interface. All of this information will be available online through the species pages of the PBI goblin spider website after the species descriptions are published. In addition, we used a novel feature of this taxonomic descriptive data base to export a phylogenetic data matrix of 1,173 taxa and 450 characters. A phylogenetic analysis with a subset of 543 taxa and 361 non redundant characters between sexes recovered these nine Malagasy species as two different clades: the former including S. curieusei plus two new species, and the latter including six new species. We emphasize that the character scoring for this 1,100+ species data set represents a collaborative effort of the PBI team of researchers, postdoctoral fellows and graduate students. |
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