West African pholcid spiders: an overview, with descriptions of five new species (Araneae, Pholcidae)

This paper summarizes current knowledge about West African pholcids. West Africa is here defined as the area south of 17°N and west of 5°E, including mainly the Upper Guinean subregion of the Guineo-Congolian center of endemism. This includes all of Senegal, The Gambia, Guinea Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo and Benin. An annotated list of the 14 genera and 38 species recorded from this area is given, together with distribution maps and an identification key to genera. Five species are newly described: Anansus atewa sp. nov., Artema bunkpurugu sp. nov., Leptopholcus kintampo sp. nov., Spermophora akwamu sp. nov., and S. ziama sp. nov. The female of Quamtana kitahurira is newly described. Additional new records are given for 16 previously described species, including 33 new country records. Distribution patterns of West African pholcids are discussed, as well as possible explanations for relatively low West African pholcid species diversity as compared to Central and East Africa

East African pholcid spiders: an overview, with descriptions of eight new species (Araneae, Pholcidae)

This paper summarizes current knowledge about East African pholcids. East Africa is defined as the area from 12°S to 5°N and from 28° to 42°E, including all of Uganda, Kenya, Burundi, Rwanda, and Tanzania. An annotated list of the 15 genera and 87 species recorded from this area is given, together with distribution maps and an identification key to genera. Most East African species (90%) belong to one of only six genera: Buitinga Huber, 2003 (21 species); Smeringopus Simon, 1890 (18); Pholcus Walckenaer, 1805 (17); Spermophora Hentz, 1841 (12); Leptopholcus Simon, 1893 (5) and Quamtana Huber, 2003 (4). Eight species for which DNA sequence data have been published recently are newly described: Buitinga batwa sp. nov., B. wataita sp. nov., Spermophora mau sp. nov., S. maathaiae sp. nov., S. bukusu sp. nov., S. kirinyaga sp. nov., S. kyambura sp. nov. and Quamtana nyahururu sp. nov. Crossopriza johncloudsleyi Deeleman-Reinhold & van Harten, 2001, previously only known from Yemen, is redescribed based on specimens from Kenya. Additional new records are given for 21 previously described species

Ninetis russellsmithi n. sp., an unusual new pholcid spider species from Malawi (Araneae: Pholcidae)

A new species Ninetis russellsmithi n. sp. is described from Malawi. It lacks the most prominent autapomorphy of pholcid spiders, the retrolateral projection of the cymbium (procursus). Biogeographically this species marks the first record for the genus in a 3000 km gap between its African congeners in Namibia and Tanzania

On the Connectivity of Unions of Random Graphs

Graph-theoretic tools and techniques have seen wide use in the multi-agent systems literature, and the unpredictable nature of some multi-agent communications has been successfully modeled using random communication graphs. Across both network control and network optimization, a common assumption is that the union of agents' communication graphs is connected across any finite interval of some prescribed length, and some convergence results explicitly depend upon this length. Despite the prevalence of this assumption and the prevalence of random graphs in studying multi-agent systems, to the best of our knowledge, there has not been a study dedicated to determining how many random graphs must be in a union before it is connected. To address this point, this paper solves two related problems. The first bounds the number of random graphs required in a union before its expected algebraic connectivity exceeds the minimum needed for connectedness. The second bounds the probability that a union of random graphs is connected. The random graph model used is the Erd\H{o}s-R\'enyi model, and, in solving these problems, we also bound the expectation and variance of the algebraic connectivity of unions of such graphs. Numerical results for several use cases are given to supplement the theoretical developments made.Comment: 16 pages, 3 tables; accepted to 2017 IEEE Conference on Decision and Control (CDC

The phylogeny of pholcid spiders: a critical evaluation of relationships suggested by molecular data (Araneae, Pholcidae)

With almost 600 species, the latest molecular phylogeny of pholcid spiders (Eberle et al. 2018, BMC Evolutionary Biology) more than triples the largest previously available molecular phylogeny of the family. At the level of genera, the coverage is high (86%, i.e., 75 of the 87 named genera), and at the level of subfamilies it is complete. The present paper is an effort to critically evaluate the implications of this phylogeny for pholcid systematics. The analyses largely support the division of Pholcidae into five subfamilies: Ninetinae, Arteminae, Modisiminae, Smeringopinae, and Pholcinae. Their compositions are largely unchanged except that Chisosa Huber, 2000 is moved from Ninetinae to Arteminae. The positions of Artema Walckenaer, 1837 and Priscula Simon, 1893 in this system remain dubious. Relationships among subfamilies remain weakly supported, except for the sister group relationship between Smeringopinae and Pholcinae. Several major clades within subfamilies are separated from each other along geographical boundaries; for example within Modisiminae a South American clade and a Central + North American + Caribbean clade, and within Smeringopinae a Sub-Saharan clade and a clade ranging from the Mediterranean to Central Asia. Central + North American + Caribbean clades in both Ninetinae and Modisiminae may originate from South American ancestors.publishedVersio

The pholcid spiders of Micronesia and Polynesia (Araneae, Pholcidae)

Records of pholcid spiders from Micronesia and Polynesia are presented, along with records from Indonesia and parts of Melanesia. Nineteen species representing eleven genera are included. An illustrated key for Pacific pholcids is provided. Two species and one genus are not yet known from Micronesia or Polynesia, but are included in the key because they may occur there. Seven species are widespread synanthropic or anthropophilic species, two species are widespread native species, and nine species are endemics of one or several neighboring islands. Distribution maps include only specimens we have seen, not literature records

Ultrafast Dynamics of Vibrational Symmetry Breaking in a Charge-ordered Nickelate

The ability to probe symmetry breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-THz response of the model stripe compound La$_{1.75}$Sr$_{0.25}$NiO$_{4}$, yielding novel insight into its electronic and structural dynamics following an ultrafast optical quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen - as witnessed by time-delayed suppression of zone-folded Ni-O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. The hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry breaking dynamics in solids.Comment: 21 pages, 4 figures; updated version with journal re

Conformation-dependent ligand hot spots in the spliceosomal RNA helicase BRR2

The conversion of hits to leads in drug discovery involves the elaboration of chemical core structures to increase their potency. In fragment-based drug discovery, low-molecular-weight compounds are tested for protein binding and are subsequently modified, with the tacit assumption that the binding mode of the original hit will be conserved among the derivatives. However, deviations from binding mode conservation are rather frequently observed, but potential causes of these alterations remain incompletely understood. Here, two crystal forms of the spliceosomal RNA helicase BRR2 were employed as a test case to explore the consequences of conformational changes in the target protein on the binding behaviour of fragment derivatives. The initial fragment, sulfaguanidine, bound at the interface between the two helicase cassettes of BRR2 in one crystal form. Second-generation compounds devised by structure-guided docking were probed for their binding to BRR2 in a second crystal form, in which the original fragment-binding site was altered due to a conformational change. While some of the second-generation compounds retained binding to parts of the original site, others changed to different binding pockets of the protein. A structural bioinformatics analysis revealed that the fragment-binding sites correspond to predicted binding hot spots, which strongly depend on the protein conformation. This case study offers an example of extensive binding-mode changes during hit derivatization, which are likely to occur as a consequence of multiple binding hot spots, some of which are sensitive to the flexibility of the protein

Cuban spider genus Ciboneya

23 p. : ill., 1 map ; 26 cm.Includes bibliographical references (p. 23).Four species of Ciboneya Pérez, n. gen. are described from western Cuba: C. nuriae, n. sp. from La Habana and Pinar del Rio provinces, C. odilere, n. sp., C. parva, n. sp., and C. antraia, n. sp. from Pinar del Rio Province. The species share apophyses on the male cheliceral fangs, corresponding pockets or modified areas on the female epigynum, and several details of the male pedipalps. Vertical hairs on the tibiae and metatarsi of the male legs and a retrolateral coxa apophysis on the male palp place the genus closer to other Central or South American genera of the New World clade of pholcids, but the exact sister group is obscure. The spiders live in the leaf litter and under rocks in humid forests, or near the floor in caves. The females of C. antraia show a remarkable dimorphism in their genitalia, with rare intermediate forms. The possibly more frequent occurrence of such a dimorphism and the probable bias toward reporting it as two different species are discussed

Speciation without changes in genital shape: a case study on Brazilian pholcid spiders (Araneae: Pholcidae

Abstract Speciation in arthropods is usually coupled with marked changes in genital morphology, which explains the usefulness of genitalia in distinguishing closely related species. The present paper describes specimens that are assigned to separate species based on extreme size differences and colour pattern differences, but the shape of the genitalia is essentially identical. We argue that such cryptic species may be more common than currently assumed, but if marked morphological (non-genital) differences are missing, traditional taxonomic methodology is biased against discovering them. The two new species from the Brazilian Atlantic Forest are tentatively assigned to the genus Psilochorus: Psilochorus itaguyrussu n. sp. and Psilochorus ybytyriguara n. sp