On Roeweriella balcanica, a mysterious species of Marpissa from the Balkan Peninsula (Araneae, Salticidae)

The taxonomic position of the poorly known species Roeweriella balcanica Kratochvíl, 1932 from Croatia is discussed. The species is illustrated and re-described on the basis of the female holotype. The genus Roeweriella Kratochvíl, 1932 (type species: R. balcanica Kratochvíl, 1932 by monotypy) is synonymized with Marpissa C.L. Koch, 1846, and therefore the new combination, Marpissa (Marpissa) balcanica (Kratochvíl, 1932) comb.nov., is proposed

A review of the Nearctic jumping spiders (Araneae: Salticidae) of the subfamily Euophryinae north of Mexico

The generic and specific composition ofthe Nearctic jumping spiders ofthe subfamily Euophryinae north of Mexico is reviewed, and the biogeographic affinities of the constituent groups are diagnosed. The five North American species of HabrocestUln are removed from that non-euophryine genus; four are placed in the New Genus Naphrys, type species Habrocestum acerbum Peckham & Peckham 1909, creating the following New Combinations: Naphrys acerba (Peckham & Peckham), Naphrys bufoides (Chamberlin & Ivie 1944), Naphrys pulex (Hentz 1846), and Naphrys xerophila (Richman 1981). The fifth species is not an euophryine, and becomes Chinattus parvulus (Banks 1895), New Combination. Four species placed in the genus Tylogonus, another non-euophryine genus, are removed to the New Genus Mexigonus, type species Sidusa minuta F.O.P.-Cambridge 1901, creating the following New Combinations: Mexigonus arizonensis (Banks 1904), Mexigonus dentichelis (F.O.P.-Cambridge 1901),Mexigonus minutus (F.O.P.-Cambridge), and Mexigonus morosus (Peckham & Peckham 1888). One of the two species of Nearctic Euophrys has been misplaced, and becomes Chalcoscirtus diminutus (Banks 1896), New Combination. New state records are reported for Chalcoscirtus diminutus [Kansas, Michigan, Minnesota, Missouri, Nebraska, New Mexico], Mexigonus minutus [California], Naphrys acerba [New Mexico], and Pseudeuophrys erratica (Walckenaer 1826) [New York]. Of the eight known euophryine genera with Nearctic representatives, Anasaitis (one species) and Cory thalia (two species) are considered Neotropical in origin, whereas Chalcoscirtus (three species), Ezwphrys (one species), and Talavera (one species) are considered Holarctic. The Palaearctic Pseudeuophrys erratica is introduced. The affinities of the apparently endemic Nearctic Naphrys (four species) and Mexigonus (four species) are uncertain at this time. Although not an euophryine, the presence of a species of Chinattus in eastern North America is biogeographically interesting, as the other species in the genus are Asian; it joins a diversity of taxa with this distribution

Further faunistic notes on Cozyptila and Xysticus from Turkey (Aranea, Thomisidae)

Nine recently described or poorly known species of the thomisid genera Cozyptila Lehtinen & Marusik, 2005 and Xysticus C.L. Koch, 1835 are reported from Turkey. Five species, Cozyptila blackwalli (Simon, 1875), C. thaleri Marusik & Kovblyuk, 2005, Xysticus bacurianensis Mcheidze, 1971, X. thessalicoides Wunderlich, 1995 and X. xerodermus Strand, 1913, are new records for the Turkish spider fauna. Two species, X. bacurianensis and X. xerodermus are illustrated and a distribution map is provided for the former. A few additional records are given for Greece and the Caucasian countries, of which X. bacurianensis is new for Azerbaijan

Lecture notes on quantitative unique continuation for solutions of second order elliptic equations

In these lectures we present some useful techniques to study quantitative properties of solutions of elliptic PDEs. Our aim is to outline a proof of a recent result on propagation of smallness. The ideas are also useful in the study of the zero sets of eigenfunctions of Laplace-Beltrami operator and we discuss the connection. Some basic facts about second order elliptic PDEs in divergent form are collected in the Appendix at the end of the notes.Comment: Lecture notes for Graduate Summer School in Park City (PCMI), July 201

Check list of the Hungarian Salticidae with biogeographical notes

An updated check list of the Hungarian jumping spider fauna is presented. 70, species are recorded from Hungary so far. Four species are new to the Hungarian fauna: Hasarius adansoni, Neon valentulus, Sitticus caricis, Synageles subcingulatus. With 12 original drawings

Gauge Fixing in the Maxwell Like Gravitational Theory in Minkowski Spacetime and in the Equivalent Lorentzian Spacetime

In a previous paper we investigate a Lagrangian field theory for the gravitational field (which is there represented by a section g^a of the orthonormal coframe bundle over Minkowski spacetime. Such theory, under appropriate conditions, has been proved to be equivalent to a Lorentzian spacetime structure, where the metric tensor satisfies Einstein field equations. Here, we first recall that according to quantum field theory ideas gravitation is described by a Lagrangian theory of a possible massive graviton field (generated by matter fields and coupling also to itself) living in Minkowski spacetime. The graviton field is moreover supposed to be represented by a symmetric tensor field h carrying the representations of spin two and zero of the Lorentz group. Such a field, then (as it is well known), must necessarily satisfy the gauge condition given by Eq.(3) below. Next, we introduce an ansatz relating h to the 1-form fields g^a. Then, using the Clifford bundle formalism we derive, from our Lagrangian theory, the exact wave equation for the graviton and investigate the role of the gauge condition given by Eq.(3) in obtaining a reliable conservation law for the energy-momentum tensor of the gravitational plus the matter fields in Minkowski spacetime. Finally we ask the question: does Eq.(3) fix any gauge condition for the field g of the effective Lorentzian spacetime structure that represents the field h in our theory? We show that no gauge condition is fixed a priory, as is the case in General Relativity. Moreover we investigate under which conditions we may fix Logunov gauge condition.Comment: 15 pages. This version corrects some misprints of the published versio