Lyristes plebejus (Scopoli, 1763)

Hertach, Thomas & Nagel, Peter, 2013, Cicadas in Switzerland: ascientific overview of the historic and current knowledge of apopular taxon (Hemiptera: Cicadidae), Revue suisse de Zoologie 120 (2), pp. 229-269 : 241-243

Lyristes plebejus (Scopoli, 1763)

German common name: Grosse Zikade ( Gogala, 2002)

French common name: La grande Cigale commune (e.g. Boulard, 1995)

DISTRIBUTION (Fig. 4)

Lyristes plebejus is the second largest European cicada after the South-Eastern European species Lyristes gemellus Boulard, 1988 , and has avery loud and distinctive song pattern. The great Swiss savant Albrecht Von Haller (1765, p. 77) knew “die echte Cicade der Alten” (= the true cicada of the ancients) from Aigle (Chablais, VD) that we assume probably refers to Lyristes plebejus .This is the first record found for cicadas in Switzerland. Fuesslin (1775) reports the species from the so-called “Italienische Vogteien” (= Italian Bailiwicks; at that period comprising the Swiss Ticino as well as the Italian Valtelline Valley and Chiavenna region) and from Roche (Chablais, VD). Schnetzler (1877) mentioned L. plebejus from Bex (VD) one century later,located like Roche in the neighbourhood of Aigle. Pillet (1993) concluded that the remarkable species must have been quite frequent in the Valais in the 19 th century referring to a notice and several specimens found in the MHNG. Milde (1866), Huber (1916) and later Schedl (2000) mentioned the species only for the most southern parts. Nevertheless, concrete historic records from Ticino are missing in the literature and in the museum collections. Vernier (1996) could not find L. plebejus in Ticino, in contrast to the local abundant C. orni during his journey in summer 1994. Schertenleib observed the species several times at Lake Neuchâtel during the first half of the 20 th century ( Vernier, 1996). We could not prove this historic occurrence, and with the recent death of Schertenleib and without information from his colleagues, the Lake Neuchâtel records remain uncertain. Vernier also mentioned anymphal skin from the Canton of Geneva found in the same period (1945) and preserved in the MHNG, but this exuvia belongs to the genus Tibicina (T.H. vidit 2010). Pillet (1993) observed the species only three times for the Valais between 1985 and 1993. Scherdlin (1910), Döderlein (1913) and Huber (1916) also reported few records from the French Alsace region which seem to be reliable.

Lyristes plebejus is currently avery rare species in Switzerland and with an unusual distribution pattern. It is mainly restricted to two established, dense populations situated in the Lugano region ( TI). The first includes the slope between Bré – Gandria –Castagnola , the second located in the San Salvatore Mountain , both with a maximum of 25 calling males. The two populations are described for the first time within this study.A third, new population seems to be established in the surrounding of Verchiez (Chablais, VD). Keim (pers. comm.) registered between two and eight singing specimens in the years 2004, 2005, 2007, 2009 and 2010. Our survey of this site revealed the presence of 10 to 12 males in 2012, but no other specimens in the

FIG.4

Distribution map of Lyristes plebejus (top) including the data source for the records presented (below).

whole region. Interestingly,Verchiez is situated in the municipality of Aigle, where Von Haller (1765) had indicated the species 250 years before.

The species can sporadically be found far away from established populations with isolated singers especially in the Lake Geneva Basin. Vernier (1996) discussed in detail one record from the Vallon d’Allondon (Russin, GE) in 1995. Further obser - vations have been made in 1999 in Gland ( VD) (♀ drowned in a pool, leg.

Breitenmoser), in 2004 at La Tour-de-Peilz (VD) (det. Martin/Göldin; Muhieddine, 2004), and potentially even in Allschwil (BL) in 2006 (Currat, pers. comm.). Established populations can be found less than two kilometres behind the Swiss border near the Poschiavo Valley (GR) in the Valtellina ( Italy). Juillerat (pers. comm.) heard one specimen singing at the Swiss side of the border in 2009 (Campocologno). L. plebejus is also currently known from the Val des Usses in Haute-Savoie ( France; Vernier, 1996 and Bal, pers. comm.).

ECOLOGY AND THREAT

The two habitats in Ticino consist of almost natural, rocky and steep slopes (Orno-Ostryon,see previous chapter). Here, at the northern limit of its range, L. plebejus is restricted to this mostly undisturbed, Mediterranean landscape, while in its core area some populations even colonize city parks. In spite of the rareness, the species does not seem to be threatened in Ticino by habitat loss. The habitats are scarcely influenced by human activities and classified as protected “dry habitats of national importance” by Swiss authorities.

In contrast, L. plebejus has become extinct in the Valais ( Keim, 1999). Pillet (1993) could not find acogent reason for the dramatic decline. The population in the Chablais is restricted to the close surrounding of three cliffs with sparse forests dominated by oaks ( Quercus sp. ). This site is almost natural as in Ticino but in vicinity of intensively cultivated vineyards. The recent observations may indicate a re-coloni - sation in the south-western part of Switzerland which could be promoted by climate change. The Chablais (VD) could play an important role for this species with its steep rocky slopes and the mild climate.