Monday 31 August 2020

Belippo eburnensis: A new species of Ant-like Jumping Spider from Côte d'Ivoire.

Belippo is a small, Afrotropical genus of Ant-mimicking Jumping Spiders, Salticidae, currently containing 12 species. It is a well-defined genus, which was last revised by Fred Wanless of the Museum of Natural History in 1978. At this time Wanless listed seven species of Belippo. Since 2013 a further five species have been described by Charles Haddad of the Department of Zoology and Entomology at the Univeristy of the Free State, Wanda Wesołowska of the Department of Biodiversity and Evolutionary Taxonomy at the University of Wrocław, and Konrad Wiśniewski of the Institute of Biology and Earth Sciences at the Pomeranian University in Słupsk. Almost all Belippo species are rarely collected, probably due to their small sizes and preferrence for concealed or hardly accessible habitats; and also due to an overall undersampling of the African Salticid fauna. Biology of the majority of Belippo species remains unknown. The available data suggest that members of this genus can occur in leaf litter or on shrubs in the forest understorey and are usually found in association with Ants.

In a paper published in the journal Arthropoda Selecta on 30 March 2020, Wanda Wesołowska  and Konrad Wiśniewski describe a new species of Belippo from Côte d'Ivoire.

The new species is named Belippo eburnensis, which is derived from the Latin name of the country of origin (Litus Eburneum). The species is described from five male and two female specimeWesołowskans collected from the vicinity of Man, Mont Toukoui, about 1200 m above sealevel, in July 2017 by Yves Braet and Arsène Gué, and housed in the collection of the Royal Museum for Centra Africa in Tervuren.

Males of Belippo eburnensis are small Ant-like Spider, with slender bodies. The cephalic and thoracic part of carapace is separated by fissure. Cephalic part higher and broader than thoracic part. Carapace black, slightly pitted, light brown streak in constriction, some white hairs at the anterior eye row, a few long dark bristles on sides of eye field and at fovea. Mouth parts and sternum brown. Chelicera dark brown, with distal prolateral spur and second minute spur on lateral keel, groove with three promarginal and six retromarginal teeth. Abdomen black, covered with short black hairs, dorsum covered with two shining scuta, constriction at one-third of abdominal length. Oblique whitish marks on lateral surface of abdomen, venter grey with large dark brown rectangular area. Spinnerets generally dark, posterior lighter. Coxae I and II yellowish, III brown, IV yellowish with dark sides. Leg I blackish, only apical end of tibia and tarsus light (in some specimens leg I lighter, yellowish with black femur only). Leg II whitish yellow, dark streaks along lateral sides of femur. Leg III: dark femur and slightly dimmed metatarsus, remaining segments light. Leg IV: blackish femur, darkened on dorsum of patella apically, two third of tibia dark, metatarsus light with dark streaks along sides. Patella I with two spines, tibia I with five pairs of long ventral spines, metatarsus with two pairs; spination of leg II similar, but on tibia only 3 pairs of ventral spines. Pedipalp blackish, tibial apophysis harpoon-shaped with three additional denticles at its base, tegulum rounded, embolus encircles bulb twice, with pars pendula.Embolic tip pincer-shaped, its two tips jointed by a membrane, viewed slightly from below it looks like a halberd. Two stout bristles on the cymbium tip.

Male of Belippo eburnensis: (1) dorsal view; (2) ventral view, (3) lateral view, (4) chelicerae, frontal view. Scale bars, 1 mm (1)–(3), 0.3 mm (4). Pierre Oger in Wesołowska & Wiśniewski (2020).

Females of Belippo eburnensis are similar to the males. Abdomen pyriform, wider behind constriction, covered with thin hairs. Colouration generally black, brighter at carapace furrow, lateral light marks in abdominal constriction, venter of abdomen grey. Chelicera with four teeth on promargin (one of them placed separately) and six on retromargin. Coxae light, except coxae III that are brown. Legs slender, generally blackish with dirty yellow patellae and distal segments, femora II yellowish with dark stripes along sides, similar streaks on tibia IV. Pedipalps oblate, black. Epigyne weakly sclerotized, with a large central depression, pockets placed at sides of the depression, the conformation is slightly changeable.  Seminal ducts membranous, thin, long, meandering; spermathecae composed of two spherical chambers connected with long ducts, second chamber surrounded by amorphous glandular tissue.

Female of Belippo eburnensis: (19) dorsal view; (20) ventral view; (21) lateral view. Scale bar 1 mm. Pierre Oger in Wesołowska & Wiśniewski (2020).

Three western African species of Belippo, namely Belippo cygniformis, Belippo ibadan and Belippo eburnensis, are closely related. Belippo ibadan has a slimmer body than in two related species. The female copulatory organs of Belippo eburnensis and Belippo ibadan are very similar and hardly distinguishable, whereas the female of Belippo cygniformis is yet unknown. Some epigynal features that can be used in distinguishing the species, such as the conformation of the extremely long and delicate seminal ducts, could be misleading, as they strongly vary depending on how the epigyne was
desiccated. The other problem concerns specimen colouration, which sometimes varies within some Myrmarachnini species. The male palpal organs in these species are rather similar and differ only in the shape of the embolic tip. It is pointed in Belippo ibadan, slightly broadened with a shallow notch in Belippo cygniformis, and clearly pincer-like in Belippo eburnensis Based on morphological characters, the two latter species are most similar to each other. In our opinion, it is very likely that these three species represent a single. phylogenetic lineage and can be united in the newly proposed cygniformis species group. Although the available data on the preferred microhabitats by Belippo species are very limited, the three related species seem to prefer slightly different microhabitats. Belippo eburnensis was collected by Malaise trap and is likely to occur on shrubs in the forest understorey, Belippo ibadan is known to occur in leaf litter, whereas Belippo cygniformis was reported as occurring in tree canopies.

Distribution of three Belippo species: circle, Belippo eburnensis; square, Belippo cygniformis; triangle, Belippo ibadan. Wesołowska & Wiśniewski (2020).

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Sunday 30 August 2020

The Aurigid Meteor Shower.

The Aurigid Meteor Shower is potentially visible each year between 28 August and 5 September each year, peaking on 31 August-1 September. This meteor shower gets its name from the constellation of Auriga in the Northern Hemisphere, from which meteors appear to radiate. However the meteor shower does not appear every year, having been only sighted four times since its discovery in 1935 by astronomers Cuno Hoffmeister and Arthur Teichgraeber (in 1935, 1986, 1994, and 2007). If the meteors do make an appearance this year, then they may not be easy to spot, as the Full Moon falls on 2 September this month.

The radiant point of the Aurigid Meteor Shower. The Sky Live.

Meteor showers are thought to be largely composed of material from the tails of comets. Comets are composed largely of ice (mostly water and carbon dioxide), and when they fall into the inner Solar System the outer layers of this boil away, forming a visible tail (which always points away from the Sun, not in the direction the comet is coming from, as our Earth-bound experience would lead us to expect). Particles of rock and dust from within the comet are freed by this melting (strictly sublimation, transforming directly from a solid to a gas due to the low pressure on it's surface) of the comet into the tail and continue to orbit in the same path as the comet, falling behind over time. 

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob. 

The Aurigid Meteors are made by the Earth passing through the trail of Comet C/1911 N1 (Keiss),  and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. 

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

Comet C/1911 N1 (Keiss) was discovered on 6 July 1911, by astronomet Carl Clarence Keiss, at the Lick Observatory on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California. The name C/1911 N1 (Keiss) implies it was the first (1) comet (C/) discovered in the first half of July 1911 (period 1911 N), and that is was discovered by Keiss.

 The current position and orbit of C/1911 N1 (Keiss). JPL Small Body Database.

Comet C/1911 N1 (Keiss) completes one orbit every 2497 years on an eccentric orbit tilted at 148° to the plane of the Solar System, that takes it from 0.68 AU from the Sun (68% of the average distance at which the Earth orbits the Sun, and slightly inside the orbit of the planet Venus) to 367 AU from the Sun (367 times as far from the Sun as the Earth, and more than three times the distance at which the planet Neptune orbits the Sun). The comet last visited the Inner Solar System in 1911. As a comet with an orbital period of more than 200 years it is considered to be a Long Period Comet.
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