Sunday, 27 December 2009

British Wildlife: Y

Before I begin the penultimate installment of the British alphabet series, I'll just say I hope everyone had a merry Xmas! Mine was full of food and frolics. Not a lot of booze though, in fact, I don't think I had any, but I didn't really need it anyway.



Yaverlandia bitholus Galton, 1971
Family incertae sedis; Saurischia; Sauropsida; Chordata

Not many scientific names begin with 'Y'. This was a difficult letter to do: it took me quite a while, with a bit of help, to find an extant British species, but I got there eventually.

Yaverlandia was described in the '70s from a partial skull, found at Yaverland Point on the Isle of Wight. It was placed within the group of ornithischian ('bird-hipped') dinosaurs known as the pachycephalosaurs. The more derived members of this group, such as Pachycephalosaurus itself, had thickened skulls which may have been used in intraspecific fights, like wild sheep (Ovis spp.) do nowadays. Under this interpretation, Yaverlandia's skull wasn't that thick, but then, being from the early Cretaceous, it predated these derived pachycephalosaurs.

Further study found that Yaverlandia wasn't a basal pachycephalosaur, nor even an ornithischian, but some kind of theropod. Since only an incomplete skull (the back of it) is known, it can't be made more specific than that. To my knowledge, there are no other prehistoric British genera beginning with 'Y', so I had to illustrate Yaverlandia. I went with the reconstruction of it as a pachycephalosaur, as I had nothing else to base it on.



Spindle ermine moth
Yponomeuta cagnagella (Hübner, 1813)
Yponomeutidae; Lepidoptera; Insecta; Arthropoda

The ermine moths are a family of cosmopolitan lepidopterans named after the appearance of some of the species, like Yponomeuta cagnagella, which are white with black spots, remarkably similar to the winter coat of the stoat (Mustela erminea), also known as ermine. This is also reminiscent of the furry borders of royal cloaks, which were traditionally made of ermine, dotted with the black tail-tips of the stoats.

The common name 'spindle' derives from the food plant of the larva, the spindle tree (Euonymus europaeus), a shrub which bears crimson lobed fruit which are toxic to humans. The larvae, like those of many other ermine moths, spin a silken web in which they gather to feed. The larvae themselves are yellow in colour, with similar black spots to the adult moths.



Yellowhammer
Emberiza citrinella Linnaeus, 1758
Emberizidae; Passeriformes; Aves; Chordata

The yellowhammer is a resident passerine found throughout Europe and parts of Asia, having been introduced to New Zealand in 1862. The male is distinctive with his lemon-yellow face and breast marked with rusty brown and black, but he is more well known for his song. It has been interpreted by humans as saying 'a bit of bread and butter with no cheeeeeeese'. In reality, it is a scratchy warble with a long last note, but all the same, it is a very distinctive sound that's always a pleasure to hear in the British countryside in early summer, when the male sings to attract a female.

Yellowhammers are buntings, a group of finch-like birds unique to the Old World. It is similar to other members of the genus, such as the reed bunting (E. schoeniclus) in build, but has brighter coloration, in the males at least.

For the final part next week (next year even!) we have Z: a megalosaur, a bright blue bug and a viviparous lacertid.

Sunday, 20 December 2009

British Wildlife: X



Xenoposeidon proneneukos Taylor and Naish, 2007
Family incertae sedis; Saurischia; Sauropsida; Chordata

Xenoposeidon was one of the largest animals ever to live in what is now the United Kingdom. It is known from only one bone, found in East Sussex in the last decade of the 19th century, geologically dating from the early Cretaceous period, some 140 million years ago. This bone is a vertebra from the rear portion of the animal, and it is incomplete; the neural arch (spine at the top of the bone) and part of the centrum (solid part at the middle) are missing. This makes it extremely difficult (if not impossible) to place the animal systematically, other than it is definitely a dinosaur, and more specifically a sauropod.

My reconstruction is based on members of the Brachiosauridae, such as Brachiosaurus and Sauroposeidon from North America, and Giraffatitan from Tanzania. Of course, it might not even be a brachiosaurid, in which case it probably was more elongated in body form, looking like the diplodocoids (including Apatosaurus and of course Diplodocus).



Xanthogramma pedissequum (Harris, 1776)
Syrphidae; Diptera; Insecta; Arthropoda

This wasp-like insect is in fact a true fly of the order Diptera. Dipterans have only two wings (hence the name), unlike most other winged insects which have an extra pair. The hind wings are vestigial, being made only of a much reduced pair of halteres, drumstick-shaped organs which are believed to aid flight. Hoverflies make up a family of dipterans which are known for their hovering flight, seen as they search for flowers from which to sip nectar. Young hoverflies, known simply as maggots, are usually more carnivorous, eating aphids and other small insects, being an important biological control agent. Other hoverfly maggots will live in dung and stagnant water, using a long breathing tube extending from the anus as a snorkel to breathe fresh air.

The featured hoverfly, Xanthogramma pedissequum, is not a common species in the UK. More widespread syrphids include Syrphus ribesii and Episyrphus balteatus, both of which are similarly patterned. This is obviously an example of Batesian mimicry: when a harmless organism mimics the warning coloration of a more dangerous one. Other examples include the milk snakes (Lampropeltis spp.) copying the coral snakes (Micrurus spp.), and the viceroy butterfly (Limenitis archippus) copying the monarch (Danaus plexippus). This works because predators learn to avoid the dangerous/toxic organism because of its warning coloration (known as aposematism) and previous experience. When the same predator sees the mimic, it will avoid that too.



Black carpenter bee
Xylocopa violacea (Linnaeus, 1758)
Apidae; Hymenoptera; Insecta; Arthropoda

OK, so its common name doesn't begin with 'X', but I'll have to make an exception for this and 'Z'. Carpenter bees are so called because they make their nests in wood. They are partially social, but nowhere near as much as the bumblebees and honey bees to which they are related. Carpenter bees are large, with Xylocopa violacea being a glossy purple-black colour. Like other bees, carpenter bees are important pollinators, visiting flowers for nectar and cross-pollinating them in the process. However, carpenter bees often 'rob' flowers of their nectar by slitting the side of the flower where the nectar is kept, hence avoiding being 'used' by the flower as a pollen-carrier. Females do sting, but won't unless provoked. The males, like other bees, lack stings as this organ is a modified ovipositor (egg-laying tube).

Next week, Y: a pachycephalosaur that probably isn't really a pachycephalosaur, a lemon-yellow warbler and a furry musteline moth.

Monday, 14 December 2009

British Wildlife: W



Westlothiana lizziae Smithson et al., 1994
Family incertae sedis; Order incertae sedis; Class incertae sedis; Phylum Chordata

Westlothiana was a lizard-like tetrapod dating to the early Carboniferous (c. 350 million years ago) rocks of eastern Scotland, not far from Edinburgh. It has so far proven impossible to know whether Westlothiana was a reptile or not. Reptiliomorphs are a group of not-yet-reptiles but no-longer-amphibians that falls outside of the Amniota clade (the members of which group have shelled eggs - this includes mammals, which ancestrally had shelled eggs). Since eggs of Westlothiana are unknown, it can't be placed with any confidence in any class, order or family.



Westlothiana lizziae fossil
Cambridge Zoology Museum
June 2009

The specific epithet, lizziae, appears to come from the informal name the holotype was given - Lizzie - due to the resemblance of the animal to a lizard.



Barred hook-tip moth
Watsonalla cultraria Fabricius, 1775
Drepanidae; Lepidoptera; Insecta; Arthropoda

The drepanids are a family of around a thousand species of moth, mostly drably-coloured. The name comes from the Greek word for 'sickle', for the shape of the wing. The barred hook-tip is found throughout most of Europe, and the larvae eat beech (Fagus) leaves.



(Dartford) Warbler
Sylvia undata (Boddaert, 1783)
Sylviidae; Passeriformes; Aves; Chordata

Dartford is either a town in Essex or a borough of south-east London, depending on your view. It is known for the eponymous tunnel that carries traffic on the London orbital motorway, known as the M25 (or, more sardonically, Britain's biggest carpark) under the Thames Estuary (at least when travelling north - south-bound traffic now goes over the river courtesy of the Queen Elizabeth II suspension bridge).

The area has also given its name to a scratchy-songed passerine - the Dartford warbler. Sylvia undata is endemic to western Europe and northwest Africa. It looks similar to several other species of the same genus found across the Mediterranean region into Asia. Dartford warblers are heathland birds, preferring coastal regions. They are uncommon in the UK, and are classified as Near Threatened by the IUCN, since much of the world population occurs in England. Harsh winters have been known to cause local extinctions, as the warbler is non-migratory and just has to put up with the British soggy winter climate and its lack of insect food, or die.

Next week, X (oh yes, I have found three species for X!): a wood-loving bee, a sauropod known only from a partial vertebra, and a bee-like fly with a larva that has a dung-snorkel.

Sunday, 6 December 2009

British Wildlife: V



Valdosaurus canaliculatus (Galton, 1975)
Dryosauridae; Ornithischia; Sauropsida; Chordata

The dryosaurids are a family of basal iguanodontians (the clade of ornithopod - bird-foot - dinosaurs including such iconic beasts as Parasaurolophus, Camptosaurus and Iguanodon). Within the family, the type genus - Dryosaurus, from Jurassic North America - is probably most well-known. There are at least two, but probably three, other genera though: Callovosaurus of Jurassic England; Valdosaurus of Cretaceous England; and Elrhazosaurus of Cretaceous Niger. The latter genus was until very recently considered an additional species of Valdosaurus, V. nigeriensis. A recent paper by Peter Galton (2009) erects the new genus for that species.

Valdosaurus canaliculatus, currently the only species in the genus, is known from parts of southern England (notably West Sussex and the Isle of Wight), as well as Romania. The generic name means "Wealden lizard", after The Weald, the part of southeast England known for its unique geology. Although only incomplete skeletons are known, enough can be inferred about the animal's body shape from more-or-less complete skeletons of its cousin Dryosaurus.



Adder
Vipera berus (Linnaeus, 1758)
Viperidae; Squamata; Sauropsida; Chordata

The adder is one of three snakes native to Great Britain (there are, of course, none at all in Ireland: if you believe the legend, St. Patrick, patron saint of the island, drove all serpents out; if you believe in cold, hard evidence, Ireland was isolated from Great Britain and mainland Europe during glaciated periods when the snakes could have migrated back from the Continent). It is, however, the only venomous snake. Despite about a hundred adder bites inflicted upon humans each year, very few have ever been fatal (about twelve in the entire 20th century), and most of these would have been people with weakened immune systems, i.e. old or very young.



Preserved female adder
Oxford Museum of Natural History
July 2008

Adders are also the only British snake to be sexually dimorphic. Males, as illustrated in the artwork, are silvery-grey with a black zigzag along the back. Females are browner overall, with a less contrasting zigzag. Famously, you can also get black adders. Apart from Great Britain, adders can also be found across Eurasia right away across to Far Eastern Russia. They also range very far north, up to the Arctic Circle.



(Water) vole
Arvicola amphibius (Linnaeus, 1758)
Cricetidae; Rodentia; Mammalia; Chordata

The water vole is a familiar rodent to many people: those who were brought up reading or watching the many TV adaptations of Kenneth Grahame's Wind in the Willows will know this animal as Ratty. Of course, the water vole is not a rat, but a plump, relatively short-tailed muroid rodent in an altogether different family, being closely related to other voles, lemmings and hamsters. You may double take at the scientific name: isn't it supposed to be Arvicola terrestris? Well, Carl Linnaeus, the father of taxonomy as we know it, described two species of water vole, a terrestrial one (A. terrestris), and an amphibious one (A. amphibius). In his tome Systema Naturae (10th ed.), which in which most of the animal species he had ever seen were described, the name A. amphibius appears on an earlier page than A. terrestris. This gives A. amphibius priority. This was only realised recently, and however much we might prefer A. terrestris, it is the other name which will stick. Unless enough people appeal to the ICZN for a reversion of the name back to A. terrestris. Anyhoo, the current name makes more sense; it's as much as a terrestrial mammal as I am an arboreal one.



Stuffed water vole
Bristol City Museum
September 2009

Water voles aren't completely aquatic of course, they are amphibious, nesting underground. They spend little time out in the open, except when feeding. The water vole in Britain has been threatened by numerous things, including draining of waterways, but most notably the introduction of the American mink (Neovison vison), a predator which specifically targets the vole as its main source of prey. Water voles are on the increase in the UK, due in part to increased conservation efforts, although mink still remain a threat.

Do not confuse this species with what is known as the water vole in North America: the species found there is Microtus richardsoni (possibly, but probably not, actually in Arvicola).

References:

Galton, P. M. (2009) Notes on Neocomian (Late Cretaceous) ornithopod dinosaurs from England - Hypsilophodon, Valdosaurus, "Camptosaurus", "Iguanodon" - and referred specimens from Romania and elsewhere. In: Revue de Paléobiologie 28(1):211-73. PDF here.

Next week, W: an Essex sylviid, a sickle-shaped moth and a Scottish reptiliomorph.