Tibicina quadrisignata ( Hagen, 1855 )

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 : 243-245

Tibicina quadrisignata ( Hagen, 1855)

German common name: Schwarzer Scherenschleifer

French common name: La Cigale quadrisignée (e.g. Pillet, 1993)

Wecould not find acommon German name for this species. “Scheereschliffer” (= scissor grinder) is an old popular and local name used for T.haematodes from southern Germany ( Geisenheyner,1887; Jacobs &Renner,1988) and representing the sound of all species of the genus in a suitable and inventive manner. The black coloration of the wing venation is diagnostic within the genus for Central European species.

DISTRIBUTION (Fig. 5)

Tibicina quadrisignata is distributed in the western Mediterranean region and has been confirmed recently for the Mediterranean regions of France ( Puissant, 2006) and for Portugal ( Sueur et al., 2004). The species is also reported from the Aosta Valley in Italy ( Schedl, 2000 and pers. data). Pillet (1993) was the first to report this species for Switzerland and presented adetailed distribution map with occurrences in the upper Rhone Valley (VS) from Grengiols to Salgesch and in parts of the very dry Visp Valleys. He concludes astrict vicariance with T.haematodes (later corrected to T.steveni ), the latter colonizing the lower,western parts of the Rhone Valley and some side valleys west of Salgesch, including the Finges Forest (VS, Sierre region).

One voucher specimen (1977, NMWI) and our acoustic recordings suggest that the Finges forest population belongs to T.quadrisignata ,five further specimens are

FIG.5

Distribution map of Tibicina quadrisignata (top) including the data source for the records presented (below).

labelled with “Sierre” (NMHN and MNHG). The limit of the known distribution range is therefore slightly shifted westward for T.quadrisignata when comparing to Pillet (1993). Moreover the allopatry seems not to be that strict. T.quadrisignata has also been found clearly west of Sierre but only very few observations can be validated: Chamoson ( Sierro &Keim, 1999; 2 ♁ leg. Carron, MHNN and private collections of Keim), Bramois [ Sierro et al.,2000; ♀ seen (Keim, pers. comm.)] and Euseigne (Praz, pers. comm.). Vernier (pers. comm.) knows one site where T.quadrisignata and T.ste- veni occur in complete syntopy in the Val d’Hérens. This range overlap makes the delimitation of the distribution areas of T.quadrisignata and T.steveni more complicated. The songs are very difficult to discriminate in the field and it is probable that Pillet was not able to verify all of his observations, neither by analysing fine song differences on computer (Sueur &Aubin, 2003) nor by checking coloration characters. There is no evidence that T.steveni occurs to the east of Sierre, and all other 19 voucher specimens of T.quadrisignata deposited in the private and public collections with reliable labels are from within the distribution area published by Pillet. Interestingly one voucher from Stalden (Visp Valleys) was determined correctly in the 19 th century (1883, det. Lethierry,NHBE). According to museum collections many specimens have been captured in this region. Our distribution map reports all voucher specimens, recent acoustic recordings and visual observations. Furthermore, Pillet’srecords were assessed as being valid if they originate from spatial unities where the suspicion on an occurrence of T.steveni is very low.

ECOLOGY AND THREAT

Tibicina quadrisignata is aspecialized species in Switzerland. It lives in very xerothermic habitats with amosaic of scattered Scots Pine (Pinus sylvestris)and Savin Juniper (Juniperus sabina), sometimes entering dry pine forests. Singing has been observed on ten different woody plants ( Pillet, 1993). Comparable habitats are occupied in the Aosta Valley. In contrast, southern French populations are most abundant in woodland (“lande haute fermée”, “bois”; Puissant, 2006). Therefore, the Swiss and adjacent Italian populations possibly form aspecialised ecotype.

The national threat to T.quadrisignata results from the following facts: the small distribution area within Switzerland, the low population densities typical of the genus, the spatial isolation at the north-eastern border of the distribution area, the stenoecious habitat requirements and habitat loss by artificial irrigation and expansion of vineyards or settlements. Moreover,the general international rareness of both the species and the specific ecotypes increase the necessity for the conservation of the species at the Swiss level. T.quadrisignata is an attractive flagship species for the driest habitats of the country and could be highlighted in nature conservation programs.