According to Dolin (1988), this species is a synonym of Ampedus nigerrimus, but Cate (2007) regards A. brunnicornis and A. nigerrimus as two separate species, a statement supported by a recent DNA study (Vuataz et al. 2019).

Delnatte (2013) studied the types specimens of A. aethiops and A. scrofa, which were often synonymised. He rehabilitated A. scrofa, whereas he considered A. aethiops sensus auctorum a synonym of A. brunnicornis.

Global and European regional assessment: Vulnerable (VU)
EU 27 regional assessment: Vulnerable (VU)

Ampedus brunnicornis is a specialist species, entirely dependent upon veteran trees. It occupies a very specific habitat type which is already highly fragmented, resulting in a severely fragmented population, and is subject to a continuing significant decline in its habitat and population. Although this species has a relatively wide distribution, its area of occupancy (AOO) is small as it is only found in veteran trees which are scattered across the landscape at very low densities. The AOO for this species is less than 2,000 km². The rate of loss of veteran trees has not been quantified, but it is significant all over Europe. Moreover, there is very little regeneration of suitable habitat across the species' range. Once the existing veteran trees have died, there will be no replacements in many areas. Even if efforts are made now to re-plant appropriate tree species, there may still be a gap during which time there would be very little suitable habitat available. Action is urgently needed to protect and appropriately manage existing veteran trees, as well as to ensure that suitable habitat continues to be available in future.

A. brunnicornis appears to be a central European species (Laibner 2000, Cate 2007), occurring at low altitudes. It is present from Poland, Slovakia and western Austria to the north-eastern of Spain (Królik 2010, Recalde Irurzun et al. 2010, Chittaro and Blanc 2012, Recalde Irurzun and San Martín Moreno 2014, Barbalat et al. 2015, Mertlik 2018).

This species has been confused with different other Ampedus (aethiops, fontisbellaquei, hjorti, nigerrimus). Delnatte fixed the taxonomy of this group recently (2013).

The species is considered rare in Europe.

In Czechia, it is locally across the whole territory (Laibner 2000). In Slovakia, its presence is marginal, on the western and north-western border, the rest of the country is occupied by A. hjorti (Mertlik 2018). In Germany it is present in seven states, six of them with records after 1950, its population is declining and it is probably the same situation in Austria. In Italy it is recorded in the north, in a few localities. In France, the species is rare but well distributed in the oak forests of the centre toward Paris and its large population in the Fontainebleau forest, as well as in Alpine valleys and the Pyrénées, reaching the Spanish side. It is considered very rare in Switzerland but largely distributed at the lowest altitudes (Barbalat et al. 2015, Info Fauna).

Over half of the population occurs in small, isolated patches with limited viability due to the fragmentation of its veteran tree habitat. It is therefore considered to be severely fragmented.

This is an obligate saproxylic species. It mostly occurs in old deciduous forests, especially oak forests (France, Germany, Switzerland). In Central Europe, it is frequent in the floodplain oak forests and in large parks and alleys (Laibner 2000, Mertlik 2018).

Larvae develop in decaying wood and cavities; largely confined to old damaged oaks (Quercus), sometimes in Populus, Castanea, Salix and Larix. This species is a specialist in large and very large trees (veteran trees, diameter >60 cm) (Sanchez et al. 2018). In Spain, it has been reported only from veteran oaks. In Germany, it is considered to be a relic of primaeval forest (Müller et al. 2005).

The larva has a mixed diet, carnivorous and saproxylophagous in both red and white rot. Adults can be found during fall in rotten wood and during spring on white flowers and the vegetation.

Removal of old dead trees and the dying off of old veteran trees with rot holes are major threats to this species. In addition, no provision of substitutes because of a demographic gap, especially of oak trees suitable to develop rot holes, leads to very little suitable habitat available for this species. Removal of trees because of road safety, unintended or intended demolition of rot-holes or intensive forest management are additional threats.

Saproxylic Coleoptera tend to be popular with beetle collectors although trade is rarely an issue, the only exceptions being a few larger species of more dramatic form or colour.

Maintenance of habitat (veteran trees) continuity and connectivity are measures that should be promoted for the conservation of this species. This species is listed as Vulnerable in Czechia (2005) and Slovakia, Endangered in Italy (2014) and Critically Endangered in Germany. It occurs in many protected areas.