PERISOMENA Walker, 1855

Perisomena Walker, 1855, List Specimens lepid. Insects Colln. Br. Mus. 5: 1199.

Type species: Perisomena caecigena (Kupido, 1825).

A genus of one species endemic to the western palaearctic and which is closely related to Caligula from the eastern palaearctic, as well as Neoris. Included in the closely related genus Saturnia by some authors.

HOSTPLANT FAMILIES: Mainly trees in the genus Quercus (Fagaceae).


PERISOMENA CAECIGENA (Kupido, 1825) -- Autumn Emperor Moth


PERISOMENA CAECIGENA CAECIGENA (Kupido, 1825)

Saturnia caecigena Kupido, 1825, Neuentdectes europäisches Nacht-Pfauen-Auge, Saturnia caecigena 4: 5.

Type locality: Fiume, Yugoslavia [Rijeka, Croatia].


A plate from Kirby (1882).

BIOGEOGRAPHICAL AFFILIATION

Holarctic; western Palaearctic region. Pleistocene refuge: Monocentric -- Pontomediterranean subsection of the Mediterranean refuge.


ADULT DESCRIPTION AND VARIATION

Male Perisomena caecigena (dwarf form = f. parviocellata), Amasya, northern Turkey. Photo: © Tony Pittaway, NHMUK.

Wingspan 62--88mm. The thinly-scaled adults can be weakly marked, mainly with an antemedial and postmedial band on each wing, each of which bears a small dark-ringed eyespot. Females are basically reddish-brown to pale wine-red with some yellowish markings, the males pale sandy yellow to deep yellow with reddish markings along the postmedial bands, although this does vary. The latter bear exceptionally large, pectinate antennae.


Male Perisomena caecigena, Krk Island, Croatia. Photo: © Tony Pittaway. Female Perisomena caecigena, Krk Island, Croatia. Photo: © Tony Pittaway. Female Perisomena caecigena, Krk Island, Croatia. Photo: © Tony Pittaway. Female Perisomena caecigena (side view), Krk Island, Croatia. Photo: © Tony Pittaway.

ADULT BIOLOGY

A nocturnal subspecies inhabiting dry, shrubby, open woodland with oaks (Quercus).


Typical habitat of Perisomena caecigena, near Madzharovo, Bulgaria. Photo: © Tony Pittaway.

This subspecies starts to emerge after the onset of cool and misty autumn nights, generally during mid afternoon, having spent the summer as a pupa. Males start to fly about an hour after darkness falls, preferring cool (or even cold), moist conditions. Females start to call (scent) about 2 hours after darkness, and can attract many males. Both sexes remain active down to temperatures of 2°C, and will even tolerate mild frosts. Males come to light, and many can frequently be seen frantically dashing around in the beams of car headlights when driving through favoured woodlands.

At rest the wings are held in a V-shape over the back in a manner similar to that of Aglia tau.

This is a short-lived, frantic species. Most individuals pair on the first night after emergence, this activity taking between 15 minutes and 2 hours. The females then try to deposit all their eggs that night, the remaining few during the next night. Few adults live more than 3-4 days once paired.


FLIGHT-TIME

Depending on latitude and altitude, late September to early November, with most out in October.


EARLY STAGES

OVUM: Rectangular, 2.5 x 2mm, glossy cream with brown gum; the overwintering stage. Females lay up to 100 eggs in batches of up to six on the twigs of trees. These hatch the following spring with the onset of warmer weather. The overwintering stage.


Eggs of Perisomena caecigena, Krk Island, Croatia. Photo: © Tony Pittaway.

LARVA: Full-fed 60mm. Monomorphic.


First instar larva of Perisomena caecigena. Photo: © Tony Pittaway.

The newly-hatched, 4.5mm long larvae, which are black with brown tubercles, consume part of their eggshells and then wander off some distance to find suitable resting sites among the unfurling spring leaves. At this stage they sit in groups on the upper surfaces of leaves and twigs. When fully grown they become solitary and are similar to the larvae of S. pavonia, in being pale green with six small yellowish tubercles per segment, a yellow subspiracular band on the abdominal segments, but with long white hairs on the tubercles. The body itself is covered with shorter white hairs.

Depending on the quality of the hostplant, the larvae may undergo four or five instars.


Second instar larva of Perisomena caecigena. Photo: © Tony Pittaway. Third instar larva of Perisomena caecigena. Photo: © Tony Pittaway. Full-grown larva of Perisomena caecigena. Photo: © Tony Pittaway.

The larvae require hot, dry conditions, and can be found during April and May.

Hostplants. Mainly species of oak (Quercus), such as pedunculate oak (Quercus robur), sessile oak (Quercus petraea), white oak (Quercus pubescens), Turkey oak (Quercus cerris), cork oak (Quercus suber) and holm oak (Quercus ilex); however, larvae have also been found on beech (Fagus sylvatica), hornbeam (Carpinus betulus), black poplar (Populus nigra), white poplar (Populus alba) and various species of ash (Fraxinus), pear (Pyrus) and Prunus.

When feeding on oak the young larvae will avidly eat the immature pollen sacks of male catkins.

In captivity this subspecies can be easily reared on Salix caprea, indicating that Salix may be a hostplant in the wild.

PUPA: Clear brown with a fine grey pubescence. Formed in a 35mm, dark brown, double-walled cocoon. The inner wall is of a fine mesh, with the outer being coarser -- the pupa is clearly visible through both. Spun up among twigs and leaves, often on or near the ground.


Pupa and cocoon of Perisomena caecigena, Krk Island, Croatia.

PARASITOIDS

Tachinidae: Exorista sorbillans (Wiedemann); Ichneumonidae: Coelichneumon erythromerus Rudow.


DISTRIBUTION

Reported in the past from the Abruzzi Mountains of central Italy as an isolated population, but this cannot be confirmed (Nässig, 2002). However, this subspecies has been confirmed east of Venice near the Croatian border (de Freina & Witt, 1987), and then from southeastern Austria (Steiermark) through Hungary, Slovenia, Croatia, Serbia, Albania, the western Ukraine, Romania, Bulgaria and Greece to most of Turkey and the Caucasus Mountains of the Republic of Georgia, Armenia and Azerbaijan (Nässig, 1981; Zolotuhin, Didmanidze & Petrov, 2011). There is also an isolated population in the mountains of Lebanon and Israel.

De Freina & Witt (1987) note a record from Sicily, but Nässig (2002) doubts the validity of this.

Extra-limital range. None.


PERISOMENA CAECIGENA STROEHLEI (Nässig, 2002)

Saturnia (Perisomena) caecigena stroehlei Nässig, 2002, Nachr. entomol. Ver. Apollo (N.F.) 23(1-2): 45.

Type locality: Cyprus, [Troodos Mts.] Paphos Forest, west of Pedoulas, east of Mylikouri, 600-800m.


BIOGEOGRAPHICAL AFFILIATION

Holarctic; western Palaearctic region. Pleistocene refuge: Monocentric -- Atlantomediterranean subsection of the Mediterranean refuge.


ADULT DESCRIPTION AND VARIATION

Wingspan (males) 40--65mm, (females) 48--90mm. This supspecies shows a very reduced sexual dimorphism compared with subsp. caecigena; however, the individual variation is larger, with the ground colour of both sexes ranging from dark brownish-red, or dark greyish-brown over wine red, to bright greyish-brown or bright pinkish brown, with any hint of yellow generally lacking in both sexes (Nässig, 2002).


ADULT BIOLOGY

A nocturnal subspecies inhabiting dry, shrubby, open montane mixed woodland with oaks (Quercus).


FLIGHT-TIME

Late September to early October.


EARLY STAGES

As per subsp. caecigena. Full-grown larvae can be found in late May.

Hostplants. Recorded from species of Quercus and Populus.

PUPA: As per subsp. caecigena.


PARASITOIDS

Unknown.


DISTRIBUTION

Confined to the Troodos Mountains of Cyprus, where it was also found by Lewandowski & Fischer (2002). It was first reported from this island by J. Lederer in 1855, from the Stavrovouni Monastary (17km west of Larnaka).

Extra-limital range. None.


OTHER SUBSPECIES

None.



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