The Lulworth skipper (Thymelicus acteon) is a butterfly of the family Hesperiidae. Its name is derived from Lulworth Cove in the county of Dorset, England, where the first specimens in Great Britain were collected in 1832 by English naturalist James Charles Dale.
The species occurs locally across Central Europe, Asia Minor and North Africa, where its population is considered stable. Its numbers have declined in Northern Europe, leading to its European status of "vulnerable". Its range in Britain is restricted to the south coast of Dorset, however it is locally abundant and its numbers currently are perhaps at their greatest since its discovery there.
With a wingspan of 24 to 28 millimetres, females being larger than males, the Lulworth skipper is a small butterfly, the smallest member of the genus Thymelicus in Europe and among the smallest butterflies in Britain. Aside from the size difference, the sexes are distinguished by females having a distinct circle of golden marks on each forewing. Due to their likeness to the rays around the eye of a peacock's feather, these are often known as "sun-ray" markings, and they can faintly appear on males.
Taxonomy
The Lulworth skipper was first described by German entomologist S. A. von Rottemburg in 1775. The butterfly was first discovered in Britain on 15 August 1832, when specimens were taken from Lulworth Cove in Dorset by English naturalist James Charles Dale. It was introduced the following year as the Lulworth skipper (Thymelicus acteon), a name that has remained unchanged; it is the only one of Britain's vernacular butterfly names for which there has never been a proposed substitute.
Description
The male Lulworth skipper has a wingspan of , and the female 25 to 28 mm. This makes it one of Britain's smallest butterflies and, in Europe, the smallest member of the Thymelicus genus. Of Britain's five "golden" skippers—the others being the silver-spotted skipper (Hesperia comma), large skipper (Ochlodes sylvanus), small skipper (Thymelicus sylvestris) and Essex skipper (Thymelicus lineola)—the Lulworth is both the smallest and darkest. Beyond its small size, it is distinguished particularly by its dark, dun-coloured wings that appear with tinges of olive-brown; this darkening especially apparent in males.
Variations are known to occur; in north-west Africa, the uppersides of the forewing and hindwing are darker, with hints of greenish or greyish brown. Similarly-coloured races occur in Spain, Elba, Crete, and other eastern Mediterranean islands. T. acteon christi, endemic to the Canary Islands, displays colour variations, with the uppersides of the forewing showing defined yellow–orange markings.
The butterfly is sexually dimorphic; females have a distinct circle of golden marks on each forewing, often called "sun-ray" markings due to their likeness to the rays around the eye of a peacock's feather. Males sometimes have these markings, though they are noticeably fainter (see Illustration 1).
Distribution and habitat
The Lulworth skipper is found locally across southern and central Europe, Asia Minor and North Africa, where its population is considered stable. In northern Europe, its numbers and range have severely declined, most notably in the Netherlands where it is now extinct. This decline has led to the butterfly's European status of "vulnerable". Isolated populations of the species in Armenia are also threatened, although not yet included in the National Red List. It is also listed as threatened under the United Kingdom Biodiversity Action Plan.
In Great Britain, where the butterfly reaches the northern limit of its range, its distribution is restricted to the southern coastline of the county of Dorset. Here, both the population and range have changed little in recent decades; it is locally abundant, with the majority of colonies found on the coast between Weymouth and Swanage and on the Purbeck Ridge, a line of inland chalk hills. Two outlying colonies also exist, at Burton Bradstock and on the Isle of Portland; the cause of the colony on Portland is unknown, but has been put down to either natural colonisation or released specimens. There is evidence to suggest that the Lulworth skipper is now more abundant in Dorset than at any other time since its discovery in 1832.
Although colonies of Lulworth skippers existed in Devon, the species has, beyond single records, not be seen in the county since the 1930s. Similarly, records of occurrences exist for Cornwall, but they have not been verified as native colonies.