Chelostoma (Chelostoma) grande (Nylander, 1852)

Heriades grandis Nylander, 1852: 277. Type material: ♀, “ Helvetia ” (Switzerland), type depository unknown.

Literature records. AUSTRIA: Kärnten, Niederösterreich, Steiermark, Tirol, Vorarlberg (Schletterer 1889; Westrich 1993; Schwarz et al. 1996). FRANCE: Alpes de Hautes-Provence, Alpes-Maritimes, Hautes-Alpes, Haute-Savoie, Savoie (Benoist 1929; Westrich 1993). GREECE: Central Greece: Pindos, Giona, Nomos Phokis near Kaloskopi (Zanden 1996, see Ebmer 2011); Panaitoliko mountain range near Proussos (Ebmer 2011); Epirus: Pindos, Lakmos, Nomos Ioannina near Anilio (Anilio (Zanden 1996, see Ebmer 2011); Pindos, Mikro Papingo (Ebmer 2011); Western Greece: Akarnaniká mountains, Nomos Etolia-Akarnania near Thyrio (Zanden 1996, see Ebmer 2011). ITALY: Liguria: Imperia, Rocchetta Nervina (Cornalba et al. 2024); Piemonte: Valle di Susa, Oulx (Westrich 1993), Torino, Cesana Torinese (Cornalba et al. 2024); Trentino-Alto Adige (Pagliano 1994; Comba 2019). KOSOVO: Peja: Kobrivnik mountains (Westrich 1993). LIECHTENSTEIN: Oberland: Triesenberg (Bieri 2002). ROMANIA: CaraȘ-Severin: Mehadia (Schletterer 1889). SLOVENIA: Gorenjska: Bohinj, Podkoren (Westrich 1993; Gogala 1999, 2014). SPAIN: Alava: Cantabrian mountains, Valdegovía/Gaubea (Pagola-Carte, 2023). SWITZERLAND: Bern, Graubünden, Obwalden, St. Gallen, Uri, Vaud, Wallis (Westrich 1993; Amiet et al. 2004; Praz et al. 2023).

New records. FRANCE: Savoie: Valle de Charmy, 1.7.1988 (leg. C. de Jong).

Distribution. In mountaineous regions in southwestern, central and southeastern Europe usually at elevations between 1000 and 2000 m (Westrich 1993): Cantabrian Mountains (Spain),Alps (Austria, France, Italy, Liechtenstein, Slovenia, Switzerland), Dinaric Alps (Kosovo), Banat mountains (Romania), Pindos, Akarnaniká and Panaitoliko mountains (Greece). The Romanian record from Mehadia by Schletterer 1889 was questioned by Westrich (1993), who suspected a possible confusion with C. transversum. However, C. transversum has never been recorded from Romania (see below) and Mehadia is located in the Banat mountains, which rise up to 1450 m, so that the occurrence of C. grande in this southern part of the Western Romanian Carpathians seems probable. In contrast, the records of C. grande by Banaszak & Dochkova (2014) from the Danubian plain and the Upper Thracian Plain in northern and central Bulgaria are certainly erroneous given the low altitude of these primarily arable landscapes. Similarly, the Bulgarian record of C. grande from western Stara planina (Atanassov 1972a, b) is most probably based on a misidentification, since the single female was collected on Medicago sativa in an agricultural field at an elevation of about 500 m, all of which is highly improbable for this mountaineous species that is specialised on Dipsacoideae. The records of C. grande from the Nur Mountains in south-central Turkey (Friese 1921) and from Azerbaijan (Maharramov et al. 2014) are also highly unlikely and probably refer to C. lucens or C. scabiosae.

Pollen hosts. Oligolectic on Dipsacoideae (Amiet et al. 2004; Sedivy et al. 2008; Westrich 1993). Main pollen hosts are species of Knautia and Scabiosa, such as K. arvensis, K. dipsacifolia and S. triandra.

Nesting biology. C. grande nests in linear cavities of about 6 mm in diameter, primarily in insect burrows in dead wood, but also in hollow bamboo stems if these are offered as nesting sites (Frey-Gessner 1880; Friese 1923; Westrich 2002). The nests discovered so far contained an empty vestibule behind the nest plug followed by 3–4 linearly arranged brood cells. The partitions between the brood cells and the nest plug consist of mud, which is mixed with small pebbles of 0.5–2 mm diameter, part of which are deeply embedded in the mud matrix. C. grande overwinters as prepupa in a self-spun cocoon within the brood cell. Metamorphosis to the imaginal stage takes place after the second or third winter resulting in a development period of two to three years. Known brood parasites are Trichodes apiarius (L.) (Coleoptera, Cleridae) and Sapyga similis (Fabricius) (Hymenoptera, Sapygidae) (Westrich 2002).

Male mating behaviour. The males patrol the flower heads of Knautia and Scabiosa in rapid flight in search of females.