Two new Australian fungus-feeding thrips in two new Plectrothripini genera (Thysanoptera, Phlaeothripinae)

Two new genera are erected of plectrothripine Phlaeothripidae from northern Australia, each based on a single species. One has a long stout projection ventrally on the second antennal segment, the other has a unique arrangement of the dorsal facets of the compound eyes. In both of them the thoracic ventral sclerites are extensively eroded. The tribe Plectrothripini is one of the few apparently discrete lineages within the large and complex subfamily Phlaeothripinae (Dang et al. 2014). The species in this Tribe are all fungus-feeders on dead branches, and the group is found in the tropics worldwide. Okajima (1981) provided an extensive, illustrated account of the Plectrothripini, recognising 10 genera and almost 50 species, to which Tyagi et al. (2016) added one further species. Six of these genera remain monotypic, with two genera each comprising five or six species, and Plectrothrips itself with about 30 species. This asymmetry of taxon distribution, with a high proportion of monotypic genera, is due to the presence of certain characters in unusual autapomorphic states. Phylogenetic relationships within the tribe are further confused here through the diagnosis of two new monotypic genera for species from the tropical north of Australia. One of these new species has a bizarre projection ventrally on the second antennal segment (Fig. 5), whilst the other has the structure of the compound eyes unique amongst Phlaeothripidae (Figs 7, 8). Membership of the Tribe Plectrothripini is fairly clear, with the species sharing most of the following character states as indicated by Okajima (1981): antennae 8-segmented, segment II with the campaniform sensillum on the basal half, III–IV with a variable number of short, stout sense cones, VIII elongate with narrow base. Head with posterior ocelli close to compound eyes. Pronotum commonly with sclerotised plate eroded and reduced; prosternal basantra absent; fore tarsal tooth large; apex of hind tibiae commonly with stout setae. Pelta wide at base, tergite II eroded laterally; sternites often with reticulate glandular areas

The work of Jaroslav Pelikan on Insects of the order Thysanoptera.

Diese Arbeit ist eine kleine Ehrung für Doc. Ing. Dr. Jaroslav Pelikán, DrSc, einen bekannten Wissenschaftler auf den Gebieten der Entomologie, Theriologie und Ökologie. Er beschrieb rund 80 neue Arten und sieben neue Gattungen von Fransenflüglern (Thysanoptera). Seine Arbeiten auf nationaler Ebene schliessen neben detaillierteren Beiträgen zur Fauna der Tschechoslowakei einige Checklisten ein. Am 22. April 2006 feierte Jaroslav Pelikán seinen 80. Geburtstag.The paper is a small tribute to Doc. Ing. Dr. Jaroslav Pelikán, DrSc, who has been a reputable scientist in the fields of entomology, theriology and ecology. He described about 80 new species of thrips as well as seven new genera of Thysanoptera. His national contributions included several checklists, together with his more complex contribution within the Fauna of Czechoslovakia. On the 22nd of April 2006 Jaroslav Pelikán celebrated his 80th birthday

Regional stratification at the top of Earth’s core due to core-mantle boundary heat flux variations

Earth’s magnetic field is generated by turbulent motion in its fluid outer core. Although the bulk of the outer core is vigorously convecting and well mixed, some seismic, geomagnetic and geodynamic evidence suggests that a global stably stratified layer exists at the top of Earth’s core. Such a layer would strongly influence thermal, chemical and momentum exchange across the core–mantle boundary and thus have important implications for the dynamics and evolution of the core. Here we argue that the relevant scenario is not global stratification, but rather regional stratification arising solely from the lateral variations in heat flux at the core–mantle boundary. Using our extensive suite of numerical simulations of the dynamics of the fluid core with heterogeneous core–mantle boundary heat flux, we predict that thermal regional inversion layers extend hundreds of kilometres into the core under anomalously hot regions of the lowermost mantle. Although the majority of the outermost core remains actively convecting, sufficiently large and strong regional inversion layers produce a one-dimensional temperature profile that mimics a globally stratified layer below the core–mantle boundary—an apparent thermal stratification despite the average heat flux across the core–mantle boundary being strongly superadiabatic

Convoluted maxillary stylets among Australian Thysanoptera Phlaeothripinae associated mainly with Casuarinaceae trees

The diversity is reviewed of Phlaeothripinae in Australia with unusually long or convoluted maxillary stylets. This comprises a total of 28 species in eight genera, including Enigmathrips carnarvoni gen et sp.n., Adrothrips latrarei sp.n., A. lihongae sp.n., A. madiae sp.n., A mitcheli sp.n., A. vernoni sp.n., and A. westoni sp.n., also Heligmothrips exallus sp.n., H. macropus sp.n., H. narrabri sp.n. and H. xanthoskelus sp.n., and Iotatubothrips daguilari sp.n. Among Phlaeothripinae, such exceptionally long feeding stylets are known only from Australia and have evolved independently within the unrelated genera Adrothrips and Heligmothrips in association with the green branchlets of Casuarinaceae species. A few species appear to have diverged in their feeding habits and have adapted to fungal-hyphal feeding on the trunks of trees

Genera of fungivorous Phlaeothripinae (Thysanoptera) from dead branches and leaf-litter in Australia

An illustrated key is provided for the identification of 39 genera of Thysanoptera-Phlaeothripinae with species that live in association with dead branches and leaf-litter in Australia and are considered to be fungus-feeding. Seven of these gen-era are not previously recorded from this continent, including un-named species of Deplorothrips, Malacothrips, Mystro-thrips, Preeriella and Tylothrips, together with Azaleothrips lepidus Okajima and Terthrothrips ananthakrishnani Kudo. A brief generic diagnosis is provided for each genus, together with comments on systematic problems and numbers of species. Copyright © 2013 Magnolia Press

Patterns of speciation in Neotropical spore-feeding thrips of the genus Zeugmatothrips (Insecta, Thysanoptera, Phlaeothripidae)

Analysis of the morphological characters of Zeugmatothrips species, all of which feed on fungal spores in leaf litter and on dead branches in Neotropical rain forests, indicates that there are two species groups, one essentially northern and the other essentially southern. Vicariant distributions can be recognised between a few species pairs, but local speciation events appear to have given rise to smaller groups of related species both in Peru and in southern Brazil. An illustrated key is provided to the 16 members of this genus

Heat transfer in rapidly rotating convection with heterogeneous thermal boundary conditions

Convection in the metallic cores of terrestrial planets is likely to be subjected to lateral variations in heat flux through the outer boundary imposed by creeping flow in the overlying silicate mantles. Boundary anomalies can significantly influence global diagnostics of core convection when the Rayleigh number, Ra, is weakly supercritical; however, little is known about the strongly supercritical regime appropriate for planets. We perform numerical simulations of rapidly rotating convection in a spherical shell geometry and impose two patterns of boundary heat flow heterogeneity: a hemispherical Y¹₁ spherical harmonic pattern; and one derived from seismic tomography of the Earth’s lower mantle. We consider Ekman numbers 10⁻⁴ ≤E≤10⁻⁶, flux-based Rayleigh numbers up to 800 times critical, and a Prandtl number of unity. The amplitude of the lateral variation in heat flux is characterised by q^{∗}_{L} = 0, 2.3, 5.0, the peak-to-peak amplitude of the outer boundary heat flux divided by its mean. We find that the Nusselt number, Nu, can be increased by up to 25% relative to the equivalent homogeneous case due to boundary-induced correlations between the radial velocity and temperature anomalies near the top of the shell. The Nu enhancement tends to become greater as the amplitude and length scale of the boundary heterogeneity are increased and as the system becomes more supercritical. This Ra dependence can steepen the Nu α Ra^{γ} scaling in the rotationally dominated regime, with γ for our most extreme case approximately 20% greater than the equivalent homogeneous scaling. Therefore, it may be important to consider boundary heterogeneity when extrapolating numerical results to planetary conditions

Assessing the importance and expression of the 6-year geomagnetic oscillation

The first time derivative of residual length-of-day observations is known to contain a distinctive 6 year periodic oscillation. Here we theorize that through the flow accelerations at the top of the core the same periodicity should arise in the geomagnetic secular acceleration. We use the secular acceleration of the CHAOS-3 and CM4 geomagnetic field models to recover frequency spectra through both a traditional Fourier analysis and an empirical mode decomposition. We identify the 6 year periodic signal in the geomagnetic secular acceleration and characterize its spatial behavior. This signal seems to be closely related to recent geomagnetic jerks. We also identify a 2.5 year periodic signal in CHAOS-3 with unknown origin. This signal is strictly axially dipolar and is absent from other magnetic or geodetic time series

A new species of Apostlethrips (Thysanoptera, Phlaeothripidae); an Australian genus from grass tussocks

In most of the warmer parts of the world, a considerable diversity of thrips live only at ground level where they feed on fungi. In Australia, many such Phlaeothripidae species live in leaf-litter (Mound et al . 2013; Wang et al . 2019), but a different and smaller suite of thrips lives particularly at the base of tussocks of grasses and similar plants (Mound & Minaei 2006; Eow et al . 2014; Mound & Tree 2018). One genus in this suite, Apostlethrips , has been known only from two species (ThripsWiki 2019), both of which were taken from the base of Triodia grasses in the northern parts of Western Australia. The purpose of the present contribution is to describe a third species in this genus, taken from grasses near Darwin. This new species shares with the other two members of the genus the unusual character of a pair of rather stout and capitate ocellar setae (Fig. 1), but it differs in several other character states. As a result, a revised generic diagnosis is provided here. Pronotal setal abbreviations are as follows: am—anteromarginals; aa—anteroangulars; ml—midlaterals; epim—epimerals; pa—posteroangulars