Saturday, 22 July 2017

Beauveria araneola: An araneogenous Fungus from Guizhou Province, China.

Pathogenic Fungi can infect a wide variety of organisms, including Plants, Animals and other Fungi. In Animals species that infect Vertebrates are well studied, but less attention has been paid to Invertebrate-infecting species, and most studies on such species have concentrated on Insects, particularly economically significant ones. Spiders have softer, more permeable integuments than Insects, and are potentially more vulnerable to Fungal infections, but far fewer species of Spider-infecting Fungi have been described than Insect-infecting species. The Spider-infecting, or araneogenous, species that have been described are generally Ascomycote Fungi closely related to Insect-infecting, or entomogenous, species, though, as with Insect-infecting Fungi, each species typically has a single host species.

In a paper published in the journal Phytotaxa on 28 March 2017, Wan-Hao Chen, of the Institute of Entomology and Institute of Fungus Resources at Guizhou University and the Provincial Special Key Laboratory for Development and Utilization of Insect Resources, Yan-Feng Han and Zong-Qi Liang, also of the Institute of Fungus Resources at Guizhou University, and Dao-Chao Jin, also of the Institute of Entomology at Guizhou University and the Provincial Special Key Laboratory for Development and Utilization of Insect Resources, describe a new species of araneogenous Fungus from Guizhou Province, China.

The new species is placed in the genus Beauveria, which also contains several Insect-infecting species, though other members of the genus are soil-living Fungi which break down dead plant and animal material, and is given the specific name araneola, referring to its host-Spider. The species is described from a single infected Spider collected from a vegetable field at the Experimental Farm of Guizhou University, and determined to be a new species by genetic analysis. 

Spider infected with Beauveria araneola. Chen et al. (2017).

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Flooding kills at least seventy three in Assam.

At least thirteen people have died after a flash flood swept through villages and farmland in Lakhimpur District, Assam, on Sunday 9 July 2017, with a further sixty people having died elsewhere in the state. The flooding destroyed 183 homes in 50 villages, and damaged over 7500 more in a further 462 villages. In addition the flooding, which largely subsided after about two days, has covered about 220 square kilometres of agricultural land with a thick layer of sand, destroying crops and potentially harming agriculture in the region for years to come.

Flooding in Lakhimpur District, Assam, on 10 July 2017. Aajtak India Today.

The flooding was caused by a release of water from the Ranganadi Hydroelectric Project in Arunachal Pradesh, undertaken to prevent stress to the dam due to high water levels following heavy rains associated with the Indian summer monsoon. This caused flooding upriver of the dam, which could potentially have led to the dam overloading, with catastrophic consequences for a wide area. The release was intended to prevent such a catastrophe, but caused the river to burst its banks about 40 km downriver of the hydroelectric project, resulting in the flooding in Assam.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

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Landslide kills at leat three at Guinea gold mine.

At least three people have died, ad several more may be missing, following a landslide at a gold mine at Bouré Boukaria in the Kankan Region in the east of Guinea, West Africa, on Thursday 20 July 2017. The bodies of two women and a man were recovered after the incident, with three other people being treated for serious injuries. The incident happened following a week of heavy rains associated with the West African rainy season. Landslides are a common problem after severe weather, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.
 The approximate location of the 20 July 2017 Bouré Boukaria landslide. Google Maps.

The incident is understood to have happened within an area granted to a multinational mining company by the Guinean government, though the victims were reportedly local artisanal miners that had entered the site illegally rather than employees of the company. Guinea is one of Africa's poorest nations, and like may other countries has granted concessions to mining companies in areas where small-scale artisanal mining has traditionally helped to supplement the incomes of subsistence farmers. However little of the money from such projects tends to reach local communities, which often leads to ill feeling and attempts to continue mining clandestinely, often at night or under other unfavourable conditions, which can put the miners at greater risk.

West Africa has a distinct two season climatic cycle, with a cool dry season during the northern winter when prevalent winds blow from the Sahara to the northeast, and a warm rainy season during the northern summer when prevalent winds blow from the Atlantic Ocean to the southwest. These warm winds from the Atlantic are laden with moisture, which can be lost rapidly when the air encounters cooler conditions, such as when it is pushed up to higher altitudes by the mountains of the Futa Jallon in Guinea.

Rainfall and prevalent winds during the West African dry and rainy seasons. Encyclopedia Britanica.

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Friday, 21 July 2017

Understanding the relationship between ocean anoxia and porphyry formation.

Porphyry formations are igneous rocks that develop along subducting plate margins. They are rich in copper, molybdenum and gold ores, making them of great interest to geologists searching for such metals. Interestingly, almost all known porphyry deposits date from the Phanerozoic (i.e. Cambrian or younger), with such formations virtually absent from Precambrian rocks. It has been theorized that this is linked to the presence of oxygen in the deep oceans; in the presence of oxygen sulphur present in magma forms sulphate compounds; these are generally incompatible with copper, molybdenum and gold, and these metals are rapidly precipitated out of the melt, forming beds rich in these metals. However, in the absence of oxygen the sulphur is found in the form of sulphides, which react well with the metals, so that they become diffusely spread throughout the magma, never reaching concentrations at which their recovery would be economically viable. If this is the case, then porphyry deposits should also be absent from Phanerozoic deposits associated with deep-ocean anoxia.

In a paper published in the journal Geology on 1 May 2017, Jeremy Richards of the Department of Earth and Atmospheric Sciences at the University of Alberta and Celâl Şengör of the Maden Fakültesi, Jeoloji Bölümü, and Avrasya Yerbilimleri Enstitüsü at the İstanbul Teknik Üniversitesi, attempt to test this theory by examining porphyry deposits along the Tethyan Margin, an ancient subductive margin running from the Alps through Anatolia, the Caucasus and the Himalayas and on into Southeast Asia, associated with the closure of the Tethys Ocean from the Carboniferous to the Cainozoic, during which periods of both ocean oxygenation and anoxia are recorded in the sedimentary rock record.

Many porphyry deposits are known from the Tethyan Margin, though these have largely been studied by economic geologists interested in finding viable sources of copper, molybdenum and gold. Richards and Şengör collated records from a wide variety of sources, to establish the age of known porphyry deposits along the margin. They found that almost all commercially viable porphyry deposits on the Tethyan Margin were associated with the Neo-Tethyan Suture, laid down in the Cretaceous and Cainozoic, with virtually none associated with the Palaeo-Tethyan Suture, laid down in the Permian to Jurassic. 

Distribution of igneous rocks associated with Paleo-Tethyan (Permian to Jurassic) and Neo-Tethyan (Cretaceous–Cenozoic) subduction and collisional closure. Richards & Şengör (2017).

This is highly indicative, as the Palaeo-Tethyan Suture is associated with a period of prolonged deep-water anoxia in the ancient Tethys Ocean, as it was increasingly enclosed by the formation of the ancient Supercontinent of Pangea from the Carboniferous onwards, preventing ocean circulation, resulting in progressive anoxia in the deep Tethys Ocean. This reached its worst during the Late Permian, when the ocean was completely enclosed and the anoxia is known to have reached the continental shelves, leading to local extinction events in even very shallow waters. The ocean slowly recovered as Pangea broke up in the Triassic and Jurassic, leading to a return to normal ocean conditions in the Cretaceous.

Paleogeographic reconstruction of the Paleo-Tethyan ocean basin during the Late Permian. Isolation from global oceanic circulation led to anoxia and the deposition of thick sequences of reduced seafloor sediments. Richards & Şengör (2017). 

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Parababinskaia elegans: A new species of Babinskaiid Lacewing from the Early Cretaceous Crato Formation of Brazil.

The Babinskaiidae are an extinct family of Lacewings (Neuroptera) best known from the Early Cretaceous Crato Formation of Brazil, as well as from the Zaza Formation of southern Siberia and Burmese Amber deposits from Kachin State, Myanmar. They are small Lacewings, with forewings 9-12.7 mm in length, differentiated from other groups by the venation of their forewings (very few specimens have preserved hindwings).

In a paper published in the journal Cretaceous Research on 15 June 2017, Vladimir Makarkin of the Federal Scientific Center of the East Asia Terrestrial Biodiversity of the Far Eastern Branch of the Russian Academy of Sciences, Sam Heads of the Illinois Natural History Survey at the University of Illinois at Urbana-Champaign, and Sonja Wedmann of the Messel Research Station of the Senckenberg Research Institute, describe a new species of Babinskaiid Lacewing from the Crato Formation, as part of a wider review of the group.

The new species is named Parababinskaia elegans, where ‘Parababinskaia’ means ‘beside-Babinskaia’ in reference to another genus which it resembles., and ‘elegans’ means ‘elegant’, in reference to the quality of the specimen from which it is described. The species is described from a single specimen from the collection of the Illinois Natural History Survey. This specimen is preserved in a slab of finely laminated limestone, and is almost complete, lacking only the legs and detail of the forewings missing (unusually the hindwings are extremely well preserved). 

Parababinskaia elegans; specimen as preserved (wetted with ethanol). Scale bar represents 2 mm. Jared Thomas in Makarkin et al. (2017).

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Thursday, 13 July 2017

Magnitude 5.0 Earthquake to the northeast of West Nusa Tenggara, Indonesia.

The Badan Nasional Penangulanggan Bencana (Indonesia's Disaster Mitigation Agency), reported a Magnitude 5.0 Earthquake about 50 km to the northwest of the city of Bima, on West Nusa Tenggara island, at about 10.30 pm local time (about 2.30 pm GMT) on Thursday 13 July 2017. There are no reports of any damage or injuries associated with this event, though people have reported feeling it on East Nusa Tenggara Island.

The approximate location of the 13 July 2017 West Nusa Tenggara Earthquake. Google Maps.
West and East Nusa Tenggara form part of the Lesser Sunda Islands, which are located on the northern part of the Timor Microplate. This is trapped between the converging Eurasian and Australian Plates, both of which are being subducted beneath it. In the south the Australian Plate is passing under the island of Timor, with material from the subducted plate melted by the friction and the heat of the Earth's interior rising through the Timor Plate to feed the volcanoes of the island. In the north the Eurasian Plate is being subducted in the same way, feeding the volcanoes there.
The subduction zones beneath the Timor Microplate. Hamson (2004).

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Wednesday, 12 July 2017

Aenigmatoconcha clivicola: A new species of Helicarionid Land Snail from northeastern Thailand.

Helicarionid Land Snails of the Subfamily Durgellinae are found on limestone hills across South China and Southeast Asia. There are currently two described genera in the group, with Sophina found in southern Myanmar and Chalepotaxis found across southern China and Taiwan. This disjunctive distribution would seem to imply the group has diverged through allopatric speciation (i.e. the different groups have become separated from one-another geographically, then become reproductively isolated through genetic drift), however it is equally likely to be due to poor sampling, which is to say the groups could quite possibly be present together across much of their range but not have been found to date.

In a paper published in the Raffles Bulletin of Zoology on 7 June 2017, Chanidaporn Tumpeesuwan, also of the Department of Biology at Mahasarakham University, and Sakboworn Tumpeesuwan, also of the Department of Biology and of the Palaeontological Research and Education Centre at Mahasarakham University describe a new species of Durgelline Snail from Loei Province in northeastern Thailand.

The new species is deemed sufficiently different from any previously described species to be given a new genus, Aenigmatoconcha, meaning ‘riddle-shell’, and given the specific name clivicola, meaning ‘dweller on the side of a hill’. The species has a flattened shell 7.69–9.89 mm in height and 15.40–18.62 mm in width, with 5¼–5½ whorls when fully grown and a large aperture. The shell is glassy and pale brown in colour, while the foot is darker brown. 

Aenigmatoconcha clivicola, in natural habitat. Kitti Tanmuangpak in Tumpeesuwan & Tumpeesuwan (2017).

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