The Spanish Festoon Zerynthia rumina, a burst of spring colour

Early spring sees the appearance in many arid parts of Catalonia of the smallest and most brightly coloured of all our
Papilionidae, the Spanish Festoon Zerynthia rumina. This unmistakable butterfly is closely tied to the birthwort Aristolochia pistolochia, a calcicole plant that is the sole food plant of the species’ larvae. Although historically the Spanish Festoon has often been thought of as a rare butterfly, it has been recorded from most Catalan comarques and even from some typically Pyrenean areas. Nevertheless, its population densities are generally quite low and its flight period is relatively short and in
many sites this species has disappeared completely by mid-May.

Geographical distribution and situation in the CBMS

The Spanish Festoon Z. rumina is only found in north-west Africa, the Iberian Peninsula and southeast France(1). In much of its range in France, it coexists with the Southern Festoon Z. polyxena, a similar species that completely replaces the Spanish
Festoon in south-east Europe(2). The Spanish Festoon is widespread in the Iberian Peninsula and has been recorded from all mainland Spanish provinces except Asturias, Vizcaya and Guipúscoa(3); it is absent only from the most northerly part of the Peninsula (that includes the highest mountains of the Pyrenees) and the Balearic Islands. In Catalonia it is one of the few species
whose range has been accurately studied (4,5). Despite living in localised and often small populations, it flies over much of the country and in 32 out of 41 comarques and with further searching it may even appear in other areas. Its distribution map suggests that it prefers low-lying areas of the coastal and pre-coastal mountains, but it also flies in much of the pre-Pyrenees and large areas of the Ebro Depression. In general this butterfly is closely tied to arid environments and avoids humid areas or
high mountains. Within the CBMS network the Spanish Festoon has appeared to date in 20 of the 76 Catalan stations (fig. 1). The greatest population densities occur in the Massif del Garraf and along the valley of the river Llobregat (for example, Sallent and
Gironella). In the mountains of Montmell and Prades, as well as in various sites in the Ebro Depression, populations are of intermediate density, while in the rest of the stations it is a rare species or is totally absent.

Habitats and food-plants

The Spanish Festoon is typically found in arid environments and in generally open and sunny and preferably calcareous habitats from sea level to midaltitude mountains up to 1,000 m (ref. 4). Data from the CBMS allows us to establish precisely which plant communities the species prefers (table 1). Using only data from sections in which the Spanish Festoon has an annual density
of over 0.1 individuals/100 m (thereby excluding observations of isolated or dispersing individuals) and taking into account only those plant communities with a section coverage of 30% or more, this butterfly is associated above all with dry false brome Brachypodium phoenicoides grassland (37% of sections) and calcareous Brachypodium retusum grassland (23% of the sections). The false brome grassland is the preferred habitat in sub-humid areas (for example, in the pre-Pyrenees and more inland mountain ranges), whilst Brachypodium retusum grassland is more often the chosen habitat in areas of semi-arid climate (Ebro Depression and some areas of the Garraf mountains). Less commonly, the Spanish Festoon is found in scrub dominated by rosemary Rosmarinus officinalis, thyme Thymus spp. and blue aphyllanthes Aphyllantes monspeliensis, in communities dominated by annual plants and Ampelodesma mauritanica or in other plant communities typical of low-lying calcareous areas. This close association with specific habitats can be explained by the monophagous nature of the species and the all but total dependence of Catalan populations on the birthwort Aristolochia pistolochia, a calcicole plant that appears in scrub under 1,200 m a.s.l. (ref. 6). Exceptionally, populations of Spanish Festoon appear in siliceous areas where A. pistolochia is not present (for example, in a few areas in L’Alt Empordà) ; it is possible that here the food plant is another birthwort, Aristolochia longa, a calcifuge species that is the preferred food plant in some populations in the south of the Iberian Peninsula (7). The bibliography also cites A. rotunda as a food plant in some European populations of the Spanish Festoon(1), although there is nothing to confirm this fact in Catalonia. Phenology and biological cycle The Spanish Festoon is a monovoltine butterfly that flies only in spring (fig. 2). Aside from areas of the pre-Pyrenees, where a few festoons are still on the wing in June, its flight period is restricted to the months of March, April and May. In the Ebro Depression and Garraf mountains the first butterflies are seen in the first weeks of March (and even at the end of February ; fig. 2a and b), whereas in more northerly locations (for example, Bages and El Berguedà) it is rare to see the species before the beginning of April (fig. 2c). In these latter areas the flight period is more compact than in the east of Catalonia, where emergence dates are more irregular. This is due possibly to the fact that in more continental areas the climate at the end of winter is more variable and depending on the
year the single annual generation of the festoon may be advanced or delayed. Even so, the averagedout data for all the years of the CBMS programme indicate that the maximum abundance of the species coincides in the three geographical areas shown in
figure 2 in the second half of April. As of yet, no evidence of a second summer-autumn generation has been found in Catalonia, as occurs in certain areas of the Iberian Peninsula (8) and Morocco (9) where A. pistolochia flowers for a lot longer. During the flight period, females festoons generally lay their eggs on the backs of leaves or on the flowers of A. pistolochia and only sometimes on the topside of leaves or on flower stalks. The eggs,

laid in clusters one-by-one or occasionally in groups
of two or three, are shiny white, just under 1 mm
in diameter, almost round, smooth and without
any type of relief. The caterpillars hatch in about
two weeks and customarily hide inside the flowers
by making a hole at the base of the inflated
corolla tube10. The caterpillars are not very mobile
and once they have grown they are easy to find on
the stalks and leaves of the host plant. They are
characteristically yellow or brown-red, with a series
of short black lines and 4-6 spines on each segment.
The larval stage lasts for around six weeks and
finishes as the host plants begin to die. The butterfly
winters as a chrysalis and –at least in captivity-
it is not unusual for two winters to pass
before the adult butterfly emerges11. We have no
information as to whether this is habitual in natural
populations.
Population tendencies
Due to pressure from collectors and the loss of habitat,
three decades ago the Spanish Festoon was
included in the first Red Data Book of Spanish
Lepidopters12

?

. Nevertheless, more recent analyses
show that the species’ populations are in fact stable13
and in Catalonia, without ever being anywhere
abundant, it is widespread and found in a great
number of sites and cannot be thought of as under
threat. Nevertheless, some populations occupy very
small, well-defined sites and so may be threatened
more than other species by the alteration and destruction
of habitat or even by collection. It seems that
La Serra de Collserola is possibly the only site in
Catalonia from which this species is documented
as having disappeared4. Albeit only on a short timescale,
it is worth pointing out that no CBMS station
has shown either positive or negative tendencies
in its populations of Spanish Festoon. At local
scale, oscillations may well be determined by the
impact of a specific parasitoid, the icneumonid
wasp, Agrypon polyxenae, which attacks the larvae
and then emerges from the chrysalis14. Nevertheless,
this affirmation needs to be tested as no data
regarding parasitism in Catalonia exists.
Constantí Stefanescu
1 Tolman, T. & Lewington, R., 2002. Guía de las
mariposas de España y Europa. 320 pàg. + 104 pl.
Lynx Edicions, Bellaterra.
2 Kudrna, O., 2002. “The distribution Atlas of
European butterflies”. Oedippus, 20: 1-342.
3 García-Barros, E., Munguira, M. L., Martín Cano, J.,
Romo Benito, H., Garcia-Pereira, P. & Maravalhas,
E. S., 2004. “Atlas de las mariposas diurnas de la
Península Ibérica e islas Baleares (Lepidoptera:
Papilionoidea & Hesperioidea) ”. Monografías Soc.
ent. aragon., 11: 1-228.
4 Viader, J., 1992. “Papallones de Catalunya.
Zerynthia rumina (Linnaeus, 1758)”. Butll. Soc. Cat.
Lep., 69: 40-52.
5 Viader, J., 1993. “Noves dades sobre Zerynthia
rumina (Linnaeus, 1758) a Catalunya”. Butll. Soc.
Cat. Lep., 71: 71-72.
6 Bolòs, O. de & Vigo, J., 1984. Flora dels Països
Catalans. 736 pàg. Editorial Barcino, Barcelona.
7 Jordano, D. & Gomariz, G., 1994. “Variation in
phenology and nutritional quality between host
plants and its effect on larval performance in a
specialist butterfly, Zerynthia rumina”. Entomol.
exp. appl., 71: 271-277.
8 Olivares Villegas, J., Jiménez Gómez, J.L. & Yáñez,
J., 1991. “Variations saisonnières de Zerynthia
rumina Linné dans le sud de l’Espagne (Lepidoptera
Papilionidae)”. Linn. Belgica, 13: 51-61.
9 Mokhles, A., 1984. “Calendrier des périodes de vol
des Rhopalocères du Marroc”. Nota lepid., 7: 257-
263.
10 Nyst, R.H. & Acquier, J.-Cl., 1984. “Nouvelles
observations concernant Zerynthia polyxena Geyer
et rumina L. (Lép. Papilionidae)”. Alexanor, 13:
239-240.
11Nel, J., 1991. “Sur la plasticité écologique et la
biologie de quelques Lépidoptères (Rhopalocera)
du sud-est méditerranéen de la France (première
partie)”. Linn. Belgica, 13: 159-220.
12 Viedma, M.G. de & Gómez Bustillo, M.R., 1976.
Libro rojo de los lepidópteros ibéricos. 120 pàg.
ICONA, Madrid.
13Van Swaay, C. A. M. & Warren, M. S., 1999. Red
Data Book of European Butterflies (Rhopalocera).
Nature and Environment, 99: 1-260. Council of
Europe Publishing, Estrasburg.
14Shaw, M.R., Stefanescu, C. & van Nouhuys, S., en
prep. “Parasitism of European butterflies
(Hesperioidea and Papilionoidea)”.
Fig. 1. Relative abundance of the Spanish Festoon
Zerynthia rumina (expressed as the value of the
annual index /100 m) in the different stations of the
CBMS network (1994-2005).
Fig. 2. Phenology the Spanish Festoon Zerynthia
rumina in (a) the Ebro Depression (data from five
stations: Timoneda d’Alfés, Mas de Melons, Granja
d’Escarp, Aiguabarreig and Sebes), (b) Garraf (data
from two stations: Vallgrassa and Olesa de
Bonesvalls), and (c) Llobregat valley (data from two
stations: Sallent and Gironella).
Taula 1. Dominant plant communities in the sections
of the different CBMS itineraries in which the
Spanish Festoon Zerynthia rumina attains population
densities of over 0.1 exemplars/100 m.
Photos. (a) Eggs nearly to hatch; (b) last instar
larva; (c) pupa; and (d) adult of Zerynthia rumina
(photographs: J. R. Salas).

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