Insects of Britain and Ireland: butterflies

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L. Watson and M. J. Dallwitz


Adults. Wingspan 30–36 mm; the fringes not banded. Medium built; short-bodied to medium-bodied. The eyes white-rimmed; notched or emarginate at the bases of the antennae and contiguous with the bases of the antennal sockets; glabrous. Antennae reaching noticeably less than halfway to the wingtips. The antennal clubs gradual-elongate. Labial palps ascending. Having all 6 legs fully developed and operational for walking. Fore-legs without a tibial epiphysis. Tibiae of middle legs 2-spurred. Posterior tibiae 2-spurred.

Forewings. Forewings apically blunt to pointed. The outer and hind margins angled at about 100 degrees. The outer margins convexly curved to more or less straight. Uppersides of the forewings lilac blue (in the male), or fuscous (in the female, sometimes blue-sprinkled); with a conspicuous discal mark (this tiny, black, in the male), or without a discal mark; plain save for a narrow dark border around costa and termen.

Hindwings. Hindwings broadly rounded; with the outer margins not scalloped. Uppersides of the hindwings lilac blue (in the male), or fuscous (in the female, sometimes blue-sprinkled); plain; without a discal mark.

Undersides of wings. Undersides of the wings multiply patterned with pale-ringed black spots.

Undersides of the forewings pale grey-ochreous, basally pale blue and black-sprinkled, with a posterior median series of 7 black, white-ringed spots and sometimes a black, white-ringed discal spot as well.

Undersides of the hindwings wings pale grey-ochreous, basally pale blue and black-sprinkled, with a posterior median series of spots black and white-ringed, likewise an anterior subcostal spot and sometimes a discal spot as well; with neither orange spots nor an orange band; with a conspicuous discal mark, or without a discal mark; without orange markings.

Wing venation. Forewings 11 veined. Forewings with 1 tubular anal vein; the anal veins of the forewings representing 1b only; vein 1b furcate proximally to simple. Forewing veins 7 missing, 8 and 9 stalked, 6 separate.

Hindwings 9 veined; without a praecostal spur; with 2 anal veins; exhibiting vein 1a; the anal veins comprising 1a and 1b. 7 veins arising from the hindwing cell. The cell-derived hindwing veins 3+4 proximally joined (connate only).

Eggs, larvae, pupae. Eggs discoid (?). The larvae woodlouse-shaped; associated with ants in the later instars. On Anthyllis and Trifolium.

Pupae exposed, with no coccoon to concealed (in a slight cocoon); not suspended, but attached at the tail and secured by a median girdle of silk.

British representation. 1 species (resident until around 1900, now known only as an ocasional immigrant). Cyaniris semiargus (Mazarine Blue). The adults abroad June and July.

Status in Britain. Rare ocurrence representing occasional, genuine immigrants and formerly indigenous but now extinct. The Mazarine Blue was regarded by Newman (1871) as “very local” in England and Wales, but it ranged from the Isle of Wight, Hampshire and Dorset north to Glamorgan, North Lincolnshire and Yorkshire. It became increasingly scarce during the second half of the Nineteenth Century, and seems to have become extinct as a British resident since around 1900. Occasional latter-day records presumably reflect sporadic migration from France, where the species is common.

Distribution. Northern England, English Midlands, East Anglia, Wales, southeast England, central southern England, southwest England, and Isle of Wight. Frequenting open places. Habitats calcareous and non-calcareous.

Classification. Superfamily Papilionoidea. Lycaenidae.

Illustrations. • Cyaniris semiargus (Mazarine Blue: photos).

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2008 onwards. Insects of Britain and Ireland: butterflies. Version: 16th May 2016.’.