No DNA differences have been recorded between Hylochares cruentatus and H. populi. It could be their differences come from a difference in substrate quality, as in small dead branches (as in the case of H. populi) animals are known to grow differently from those in large woody pieces with more humidity.

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

This species is actually now only known from Russian Karelia. Other subpopulations, reported from the EU27, are very old unique records, which are very probably extinct or in poor condition. Hylochares populi is associated with large and very large dead wood of aspen, a tree strongly threatened by forestry outside Karelia. The Karelian population is probably stable as long as forest exploitation remains limited in this area. However, this situation is unlikely to remain in this state of equilibrium over the medium term. It is assessed as Vulnerable under criterion D2 as the species has a small range (area of occupancy = 36 km²) and if the forest area it is known from becomes exploited, the removal of large amounts of deadwood that this species relies on could result in it moving to Critically Endangered in a short space of time. It is assessed as Data Deficient for the EU 27 region as it is not known whether the species is extant in the region.

It is a recently described species from Russian Karelia and recently only reported from this area (Brüstle and Muona 2009). Other countries of occurrence are listed without precision and on the basis of old data only: Estonia (records from before 1937), Latvia (recorded before 1831), and Poland (recorded before 1860) (Muona and Brüstle 2008, www.beetlebase.com).

The species is also reported from the Altai mountains although its presence is not certain. For its describers, it is possible that Hylochares populi has been very recently isolated from H. cruentatus by the last glaciations.

It is an overlooked species whose presence has only been confirmed in Russian Karelia.

In the Baltic States and Poland, there are only old records indicating that Hylochares populi may have disappeared from its old locations. No populations were found in Finland where the presence of the species' host tree has been reduced by the forest exploitation for many years.

The population trend is considered to be declining, as is its habitat.

Brüstle and Muona (2009) suspected the existence of this new species based on the observation of two very different biologies attributed to Hylochares cruentatus. Hylochares cruentatus lives in the hard wood of small Salix trees (diameters about 15 cm), while H. populi lives exclusively in large soft rotten pieces of Populus tremula. Stumps utilised have diameters larger than 50 cm (Kangas and Kangas 1944 under the name Xylophilus cruentatus). Muona (1993) reports diameters of about 110-130 cm for the host tree dead trunks. The wood burrowed into by larvae is transformed by white rot. The larvae develop over a year.

The specific biological requirements of this species (dead wood of large and veteran aspens) make it threatened by forest exploitation which dramatically remove those large trees in the north of Europe.

Despite directed searches by J. Muona (pers. comm. 2023), no populations of Hylochares populi have been found in Finland where aspen has been reduced by the forest exploitation for many years. On the other hand, in Karelia, Siitonen and Martikainen (1994) have noted that the presence of H. populi (named Rhacopus attenuatus in this article) is “attributable to the different management history of the forests, particularly to the abundance and continuity of large, dead aspens”.

No indications of use or trade are known for this species.

This species has been recorded in a protected area in Karelia, the Vodlozero national park. Research is needed to improve knowledge of the distribution, biology and threats to this species in Europe. The population trend should be monitored in view of potential threats to the hosts.