Global and European regional assessment: Near Threatened (NT)
EU27 regional assessment: Near Threatened (NT)

Microrhagus pyrenaeus is a European species of saproxylic beetles bound to temperate forests. The European and EU27 extent of occurrence (EOO) are large, exceeding the threshold for threatened species. The potential area of occupancy (AOO) is below 2,000 km² and meets the threshold for Vulnerable. The population is fragmented but likely increasing, although it remains unknown are the more frequent observations of this species resulting from an increasing population or from more efficient recording / sampling techniques applied in the last decade to monitor this species. Whilst the available habitat is large, there are continuing declines in the amount of decaying wood used by this species. The species is therefore assessed as Near Threatened, both globally and in the EU 27 region, as it is close to qualifying for Vulnerable (B2ab(iii)).

This species has a patchy distribution across western and central Europe from the Pyrenees to Poland, Greece and Bulgaria (Muona 2007, Mertlik et al. 2009, Chittaro and Blanc 2012, De Zan et al. 2014, Vávra et al. 2014, Hilszczański et al. 2015, Schünemann 2016, Krátký 2017, Vávra et al. 2021). In France, it is widespread but very rare (B. Dodelin pers. comm. 2024). It was considered Extinct in Germany (B. Büche pers. comm. 2009) until it was recently rediscovered (Schünemann 2016). Single records are known from Bulgaria, Greece and Poland. It is possibly extant in Belarus considering the locality in the Polish part of the Bialowieza Forest. The known European and EU27 extent of occurrence values are large, exceeding the threshold for threatened species. The known European and EU27 area of occupancy (AOO) is below 500 km², but the species is under-recorded and understudied and the potential European and EU27 AOO is likely between 1,500-2,000 km².

There is little information available on the abundance of this species. It was previously considered one of the rarest saproxylic beetles in Europe (Brustel and Van Meer 2008), but there are more than ten new published records from various European countries within the last two decades. The population appears fragmented, but the habitat is not. The beetle remains uncommon and enigmatic, but not an extreme rarity anymore (Vavra et al. 2021).

This is an obligate saproxylic species. It has been found in dry branches of Carpinus in Germany (Muona 1993). In France it was found in humid and cold lowland forests, developing in white-rotten wood (branches) of Alnus and, mainly, Quercus, lying on the ground (Brustel and Van Meer 2008), clearly preferring large and old trees (B. Dodelin pers. comm. 2024). In Germany and Poland, larvae of Microrhagus pyrenaus develop in decaying wood of fungi-infested branches causing white decay; development recorded in dead branches of Alnus, Carpinus, Quercus and, likely, Fraxinus (Hilszczański et al. 2015, Schünemann 2016). The available habitat is large but is inferred to be continually declining.

The general threat is a general decrease of the amount of decaying wood in forested landscapes caused by extensive forestry practices. Fragmentation and increasing isolation of beetle populations are likely key factors.

It is used for scientific research.

This species occurs in nature conservation areas across its range (e.g. in Poland). No specific measures are in place. Additional studies are required on the ecology and threats of Microrhagus pyrenaeus.