Small whiteface
The white-faced darter or small whiteface (Leucorrhinia dubia) is a dragonfly belonging to the genus Leucorrhinia in the family Libellulidae, characterised by red and black markings and a distinctive white patch on the head. It is found in wetlands and peat bogs from northern Europe eastwards to Siberia, and the adults are active from around April till September, which is known as the "flight period". It breeds in acidic bodies of water, laying its eggs in clumps of sphagnum moss that provide a safe habitat for larval development. The larvae are particularly vulnerable to predation by fish, and so are usually found in lakes where fish are not present. L. dubia is listed as a species of least concern (LC) by the IUCN Red List, however, it is potentially threatened by habitat destruction, pollution, and climate change.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withThis species has a predominantly black body, usually 33–37 mm (1.3–1.5 in) in length - the abdomen is 21–27 mm (0.83–1.06 in) long and the hindwing is 23–28 mm (0.91–1.10 in) long. Mature males have striking red and orange markings on the abdomen and thorax which become darker with age, whereas young males and females have pale yellow markings. All individuals have a conspicuous white frons at the front of the head. The wings have a brown patch at the base and noticeable black pterostigma. It may be confused with similar species, including the black darter (Sympetrum danae), ruddy darter (Sympetrum sanguineum) and common darter (Sympetreum striolatum), however is usually distinguishable by its white face patch.
This dragonfly's range extends from western Europe to Japan, and it is commonly found in western, northern and eastern Europe at higher altitudes, but is rare in southern Europe and the United Kingdom. In recent decades, this species has been observed as far afield as Russia and China, however the vast majority of sightings have occurred in central and northern Europe. In Britain, the majority of individuals of this species are found in the highlands of Scotland, with key populations located in Inverness-shire and Ross-shire. In England, a few isolated populations occur in Cheshire and Cumbria, where biodiversity action plans have been set up to protect them, and as far south as Chartley Moss National Nature Reserve in Staffordshire. However, when British populations are considered overall, this species has been in decline over the past 35 years.
Adult individuals of L. dubia can utilise scrub and woodland habitat for roosting and foraging. The larvae require terrestrial areas of water, such as marshes, wetlands and peat bogs, that generally have vegetation growing at the water's edge. Peat bogs form a particularly important habitat, since they provide acidic conditions necessary for the growth of sphagnum moss, which provides a source of food and shelter.
L. dubia is vulnerable to alteration and destruction of its habitat, primarily due to water pollution, industrialisation, and development for agriculture. It is protected by the Wildlife and Countryside Act 1981 in the United Kingdom, where 95% of lowland peat bogs have been destroyed, and it is also covered by Biodiversity Action Plans in some British counties. Conservation reintroduction programmes have been shown to be a successful method for restoring populations to suitable sites, and in 2010 it was reintroduced to Witherslack Mosses in Cumbria, after 13 years of restoration management.
Isolated, fragmented populations are at an increased risk of local extinction due to a lack of exchange of genetic variation, resulting in potential inbreeding depression and increased impact of sudden, random events such as disease outbreaks. Populations of L. dubia in the UK, the Pyrenees and the Alps have been found to be more genetically distinct than other European populations, and may therefore be considered priorities for conservation, as they are likely to retain important genetic variation for adapting to changing climate conditions.
A rise in average annual temperatures caused by global warming could negatively impact L. dubia by allowing invasive species such as the scarlet dragonfly (Crocothemis erythraea) to occupy habitats further north of their natural range. Although the growth rate of L. dubia doesn’t appear to be affected by temperature, C. erythraea can grow faster at higher temperatures, causing L. dubia to suffer higher levels of competition and mortality.
Due to the particular sensitivity of the larval stage to the presence of fish, this species could be threatened by the practice of artificially stocking lakes with fish for the purpose of recreational fishing. The process of liming acidified lakes, to increase their pH and restore fish populations, also poses a threat by reducing the amount of sphagnum moss present. Acidic lakes where fish are naturally absent could be of high conservation value for this species.
L. dubia is listed as a species of least concern (LC) by the IUCN Red List, meaning that it is not currently considered to be threatened by extinction. This categorisation applies to the species when all populations are considered across its entire range. However, it is red-listed in a number of European countries within its range, including Germany, Austria, Switzerland and the UK. Greater research and monitoring is currently required on population distribution and trends, to better understand how this species will fare in the future. Most of the recent scientific research has been conducted in central and northern Europe, and less is known about eastern populations in Siberia, where L. dubia is rarely seen.
