According to Wood (1967) and Horn et al. (1990b), Ratzeburg’s material was destroyed during WWII. The authors have confirmed that the material was not present at the listed museums in Horn et al. (1990B), and it is therefore presumably destroyed.

We designate a neotype of Cryphalus piceae with the express purpose of clarifying the taxonomic status. The original description was based on specimens collected either in Upper Silesia (Poland) or Bavaria (Germany) (Ratzeburg 1837). A neotype of Cryphalus piceae (Ratzeburg, 1837) was designated (Fig. 9). It is a male collected 14/02-2018 in Austria (48°04'31.3"N, 15°21'31.6"E) from an Abies nordmanniana (Steven) Spach branch, not far from Bavaria. The specimen will be stored at NHMD in the entomological collections. COI sequence (Fig. 8; A.7 Hummelbach) is from a specimen collected in the same branch as the neotype.

Figure 9. 

Neotype of Cryphalus piceae, stored at NHMD in the entomological collections.

474 specimens from various locations in Europe (Table 1) were examined. Morphological measurements were made on 33 specimens from Austria (7), Germany (12) and Hungary (14). The average results are shown in Fig. 2.

This species can be diagnosed from morphologically similar Cryphalus in Europe by the combination of a circular pronotum that is anteriorly constricted, asperities (> 50) on pronotum in almost concentric circles, long erect interstrial setae on the elytral declivity approximately same length or only slightly longer than width of second interstria. For confident identification the male genitalia is unique. The penis body when seen from above (dorsally) is equally broad and asymmetric, slightly spiralled. The entire aedeagus is ~ 0.6 mm in length (Fig. 10B–E).

Figure 10. 

Cryphalus piceae A distribution B lateral and dorsal view C aedeagus D SEM, specimen from Sopron, Hungary E SEM (43× magnification), specimen from Sopron, Hungary.

Length 1.45–1.93 mm, average size 1.73 mm (neotype 1.85 mm). Proportions 2.21× as long as wide, elytra 1.35× as long as wide, elytra 1.72× as long as pronotum. Antennae: club with three procurved sutures marked by coarse and long setae. Funiculus with four antennomeres (with pedicel). Pronotum: dark brown to black on both slope and disc. Profile anterior to summit rounded but slightly constricted anteriorly, wider in line with summit. Anterior margin with 4–8 asperities, the outer one or two pairs usually smaller; erect setae on entire lateral margin of pronotum. Anterior slope with > 50 asperities, including the ones on the anterior margin. Disc ~ 1/4 the length of pronotum, gently sloped, weakly tuberculate surface texture with small hair-like setae in each tubercule. Vestiture on pronotal declivity and disc hair-like. Suture between pronotum and elytra weakly sinuate. Scutellum: with trifurcate setae on the margin towards elytra (only visible at high magnification). Elytra: usually brown to black, if brown often darker at base, sometimes well-developed adults are light brown, elytral margins slightly wider 2/3 from base. Elytral declivity regularly rounded. Surface smooth. Striae with rows of punctures, each puncture with a short hair-like seta, punctures sometimes visible. Interstrial setae long (0.13–0.23 mm) and erect. Interstrial ground vestiture (scales) are serrated, ~ 2–3× as long as wide and translucent brown with a weak iridescence (Fig. 10B, D, E). Proventriculus: sutural teeth of irregular size, confused, in two or more longitudinal rows. Apical teeth extend laterally over the entire segment. Masticatory brush slightly < 1/2 of the proventricular length (Fig. 7). Proventriculus also illustrated in Escherich (1923).

Sexual dimorphism. Males and females can be separated using the last ventrite (Fig. 11), as suggested by (Johnson et al. 2020a). Wood (1982) also suggests that the sexes of several scolytines including Cryphalus, can be separated by males having a clearly visible 8^th tergite and the females a highly reduced or absent 8^th tergite. This character was not examined. We observed some small external differences between males and females. The females (1.77 mm) were slightly larger than males (1.68 mm), and the interstrial setae were overall longer on the females (0.20 mm) compared to the males (0.16 mm). However, there were a considerable overlap between males and females. No clear difference in tubercles or carina on the frons was noticed.

Figure 11. 

Sexual dimorphism of ventrite in Cryphalus spp.

Male. The entire aedeagus is ~ 0.6 mm when measured vertically (i.e., from the two points furthest away from each other, Fig. 5). The penis body when seen from above (dorsally) is asymmetrical, evenly broad, and spiralled. Aedeagus apodemes makes up ~ 30% of the entire aedeagus length when measured vertically, they are spiralled and bending downwards. The tegmen is sclerotised and completes a ring around the penis body. It is thin and has two thin ventral apodemes, which are approximately the length of the distance between them (Figs 5, 10C).

Larvae. The larvae are described by Kalina (1970).

The main hosts of C. piceae are Abies Mill. and Picea Mill. (Escherich 1923; Pfeffer 1995; Wermelinger et al. 2002). In a study on bark beetles which was designed to test their specificity on different conifer hosts, it was found that among Abies, Picea, Pinus L., and Cupressus L., C. piceae preferred Abies and Picea (Chararas et al. 1982).

Cryphalus piceae is found in Europe: Austria, Bosnia-Herzegovina, Bulgaria, Belarus, Croatia, Czechia, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Macedonia, Montenegro, Poland, Romania, Slovakia, Slovenia, Spain, Switzerland, Ukraine, Russia: Central European territory, South European Territory. North Africa: Algeria. Asia: Japan, North Korea, South Korea, Turkey, Russia: Far East, China: North East Territory (Knížek 2011; Alonso-Zarazaga et al. 2023).

Cryphalus piceae has a more southerly distribution. Until now the northernmost record was Denmark (Justesen et al. 2020), but it was recently collected in southern Sweden (Lindelöw and Jonsell 2022). It is found in most of central and southern Europe where Picea and Abies are present. It has been mentioned from Algeria (Knížek 2011), and possibly also Morocco (Benhalima et al. 2005). However, the distribution of C. piceae may be confused with C. numidicus in North Africa and in the Mediterranean in general, because of the similar appearance of the two species. Wood (1992b), Sarikaya and Avci (2011) and Cilbircioğlu and Ünal (2012) have mentioned C. piceae from Turkey and in the present study we barcoded individuals from Caucasus (Georgia) (Fig. 8). Further studies are needed to understand the distributional overlap and extent of both species. Similarly, the East Palearctic distribution of C. piceae is not sufficiently studied as was highlighted by our molecular data (Fig. 8). It is possible that C. piceae is present all the way across Russia and parts of China to Japan and Korea (Inouye and Nobuchi 1957; Wood 1992b), but this needs further clarification. As Abies is absent from the European part of Russia, the presence of C. piceae in this area, is dependent on reproduction in other conifer hosts. See Fig. 10A for distribution.

During the winter adult C. piceae hibernate individually on healthy trees, by excavating short tunnels into the phloem (Justesen et al. 2020). Rarely do they also hibernate as larvae or pupae in dead trees or branches infested earlier in the season (Toper 2002). The hibernating adults begin activity around mid/end of March, depending on temperatures (Justesen et al. 2020). During March and April C. piceae aggregates on suitable material and mates. The preferred material is weakened parts of trees, or any smaller branches that have broken off during the winter season and are still relatively fresh. After mating they excavate a nuptial chamber, and the female lays 5–26 eggs (Cerchiarini and Tiberi 1997; Toper 2002). The development time from egg to adult depends on temperature. Most commonly, there are two generations a year plus a sister generation; however, in colder regions C. piceae only has one generation a year (Justesen et al. 2020).

The harmful properties of C. piceae are discussed in detail in Justesen et al. (2020), but most likely C. piceae only colonise very weak or recently dead trees. The low impact on host tree survival during colonisation was also confirmed by Justesen et al. (in press B). However, in areas where C. piceae reach very high population densities, their ability to penetrate and overwinter in healthy trees could potentially have negative impacts. This could be through lowered tree growth, as the overwintering beetles cause the tree to invest energy into excreting resin from the penetrations. Additionally, the movement from dead or dying trees to healthy trees, could potentially vector fungal diseases, thereby affecting host tree survival. However, the negative impacts of overwintering beetles remain to be explored (Justesen et al. 2020).

The shape and size of the aedeagus is the best character to ensure correct identification. The penis body when seen from above is asymmetric and slightly spiralled in C. piceae, and highly asymmetric and spiralled in C. numidicus. The entire aedeagus is slightly longer (0.6 mm) and broader in C. piceae compared to a shorter (0.5 mm) and thinner aedeagus in C. numidicus.

Both Grüne (1979) and Noblecourt and Schott (2004) mentioned that the pronotum is anteriorly constricted (dorsal view) (Grüne 1979) or slightly narrowed in the front (Noblecourt and Schott 2004) in C. piceae compared to the rounder pronotal shape of C. numidicus. In the original description of C. numidicus this character is also mentioned (Eichhoff 1878a). This character was partly confirmed. The comparison between the width of pronotum at the widest compared to the width between apex and summit (Fig. 3), generally showed a more rounded shape in C. numidicus compared to C. piceae, but with a high degree of overlap.

Noblecourt and Schott (2004) mentioned C. piceae with shorter setae on the lateral margins of pronotum and elytra compared to C. numidicus. During our examinations we also noticed these hair-like setae were shorter in C. piceae. Additionally, we found that the lengths of the interstrial hair-like setae on the elytral declivity are markedly shorter in C. piceae (0.13–0.23 mm) compared to C. numidicus (0.20–0.38 mm). The longer setae on elytra were also mentioned in the original description of C. numidicus (Eichhoff 1878a).

Noblecourt and Schott (2004) and Pfeffer (1995) used size as a good separating character between C. piceae (1.1–1.6 mm) and C. numidicus (1.3–2 mm), whereas Grüne (1979) measured C. piceae (1.1–1.8 mm) to be similar sized to C. numidicus (1.2–1.8 mm). The original description by Eichhoff found C. numidicus to be between 1.3 and 1.6 mm (Eichhoff 1878a). Our measurements did not find a size difference between C. piceae (1.45–1.93 mm) and C. numidicus (1.50–1.88 mm), but the 16 measured C. numidicus specimens were all collected from the same tree.

According to Horn et al. (1990a), Eichhoff’s bark beetle material was transferred via C. Schaufuss and then again via H. Eggers to the Zoological Museum in Hamburg. According to Wood (1992a), the C. numidicus material in Hamburg was destroyed. Contact with the Zoological Museum in Hamburg confirmed that the material (if there) was destroyed (pers. comm. Husemann, November 2018).

We designate a neotype of Cryphalus numidicus with the express purpose of clarifying the taxonomic status. The original description was based on specimens collected in Greece (Eichhoff 1878a). A male neotype of Cryphalus numidicus (Eichhoff, 1878) was designated (Fig. 12). It was collected on 31 March 2019 in Greece (37°03'21.9"N, 22°48'44.8"E) from an Abies cephalonica Loudon tree that had recently fallen. The specimen will be stored at NHMD in the entomological collections. COI sequence (Fig. 8, NUM1 and NUM) are from specimens collected in the same branch as the neotype.

Figure 12. 

Neotype of Cryphalus numidicus. Stored at NHMD in the entomological collections.

55 specimens from a single location in Greece (Table 1) were examined. Morphological measurements were done on 16 specimens from that location. The average results of the measurements are shown in Fig. 2.

This species can be diagnosed from morphologically similar Cryphalus in Europe by the combination of circular pronotum, asperities (> 47) on pronotum in almost concentric circles, very long erect interstrial setae on the elytral declivity longer than width of second interstria. For confident identification, the male genitalia is unique. The penis body when seen from above (dorsally) is equally broad and highly asymmetric, spiralled. The entire aedeagus is ~ 0.5 mm in length (Fig. 13B–E).

Figure 13. 

Cryphalus numidicus A distribution B lateral and dorsal view C aedeagus D SEM, specimen from Leonidio, Greece E SEM (43× magnification), specimen from Leonidio, Greece.

Length 1.5–1.88 mm, average size 1.68 mm. Proportions: 2.15× as long as wide, elytra 1.30× as long as wide, elytra 1.65× longer than pronotum. Antennae: club with three procurved sutures marked by coarse and long setae. Funiculus with four antennomeres (with pedicel). Pronotum: dark brown to black on both slope and disc. Profile anterior to summit rounded, wider in line with summit. Apical margin with 3–7 asperities, the outer one or two pairs usually smaller, erect setae on entire lateral margins. Anterior slope with > 47 asperities, including the ones on the anterior margin. Disc between 1/4–1/5 the length of pronotum, gently sloping, weakly tuberculate surface texture with a small hair-like seta in each tubercle. Vestiture on declivity and disc hair-like. Suture between pronotum and elytra weakly sinuate. Scutellum: with few trifurcate setae on the margin towards elytra (Fig. 13D). Elytra: usually brown to black, if brown often darker at base, margins equally wide. Surface smooth. Striae with rows of punctures, each puncture with a short hair-like seta, punctures sometimes visible. Interstrial setae long (0.20–0.38 mm) and erect. Interstrial ground vestiture (scales) are serrated, ~ 2–3× as long as wide and translucent brown with a weak iridescence (Fig. 13B, D, E). Proventriculus: sutural teeth of irregular size, confused, in two or more longitudinal rows. Apical teeth extend laterally over the entire segment. Masticatory brush slightly < 1/2 of the proventricular length (Fig. 7).

Sexual dimorphism. Males and females can be separated using the last ventrite (Fig. 11), as suggested by (Johnson et al. 2020a). Wood (1982) also suggests that the sexes of several scolytines including Cryphalus, can be separated by males having a clearly visible 8^th tergite and the females a highly reduced or absent 8^th tergite. This character was not examined. The females (1.74 mm) are on average slightly larger than males (1.66 mm). No clear difference in tubercles or carina on the frons was noticed.

Male. The aedeagus is approximately 0.6 mm and the penis body is 0.4 mm, when measured in dorsal view from the two points furthest away from each other (Fig. 5). The penis body when seen from above (dorsally) is highly asymmetrical, equally broad, and clearly spirally twisted. Aedeagus apodemes make up ~ 40% of the entire aedeagus length when measured from dorsal view, they are spiralled and bending downwards. The tegmen is sclerotised and completes a ring around the penis body. It is very thin and has two thin ventral apodemes, which are approximately the length of the distance between them (Figs 5, 13C).

Larvae. Nothing is known about the characteristics of the larvae of this species.

In North Africa C. numidicus is known to occur on Abies pinsapo Boiss., A. numidica de Lannoy ex Carrière, Pinus halepensis Mill. and Cedrus atlantica (Endl.) Manetti ex Carrière (Lieutier et al. 2016). In Europe it has been found in A. pinsapo, P. halepensis (Pfeffer 1995; Lieutier et al. 2016). We collected it from A. cephalonica.

According to the Palearctic catalogue (Knížek 2011), C. numidicus is found in Europe: Bulgaria, France, Greece, Italy, Spain, Switzerland; North Africa: Algeria, Egypt, Libya, Morocco, Tunisia. Asia: Turkey.

Except for Switzerland and Bulgaria, the current distribution of C. numidicus is confined to the Mediterranean region, following the distribution of the host species mentioned above. It is unclear if C. numidicus occur on Abies bornmuelleriana Mattf., Abies cilicica (Antoine & Kotschy) Carrière and A. nordmanniana in the East Mediterranean region, or if it is only C. piceae that occurs there. We collected it in Greece from A. cephalonica. See Fig. 13A for distribution map.

We found adults in mating galleries near Kounoupia in Greece (37°03'21.9"N, 22°48'44.8"E) on 31^st March 2019, on an A. cephalonica branch, attached to a tree that had fallen during winter, where the bark was still relatively fresh. The branches were recently infested, so activity must have started already in mid-March. This could suggest the possibility of two generations a year. A study by Beghami et al. (2020) showed that C. numidicus from Algeria was active in spring, summer, and autumn and that it could reach three generations per year, with two sister broods in early spring and summer and the second generation in mid-September to early November (under favourable weather conditions). Lieutier et al. (2016) stated “The species develops quickly and produces 1–2 generations per year depending on climatic conditions” and “the adults bore very irregular galleries (often invaded by fungi) within the phloem of thin bark on small branches of healthy trees”.

According to Lieutier et al. (2016), C. numidicus can cause primary damage if the population density is high and the species can be regarded as a primary and extremely dangerous pest because of its ability to infest and reproduce massively in young healthy trees. The species infests and kills apparently healthy hosts, causing the death of trees (Lieutier et al. 2016). Following Berghami et al. (2020), C. numidicus is a “pioneer” species able to establish on relatively freshly cut material, only four months old. Cryphalus numidicus prefers the middle and top part of trees and branches of small diameter. Attacks on cedars are initiated by both C. numidicus and Phloeosinus cedri C.N.F. Brisout de Barneville, 1883; however, only the latter can attack the crown and the mid-trunk of healthy cedars. After P. cedri attacks, C. numidicus further impairs cedar defences through massive attacks (Beghami et al. 2020).

For discussion on the diagnostic characters separating C. numidicus from C. piceae, see remarks for the latter species.

According to Horn et al. (1990a), the type material was stored at the Natural History Museum in Vienna. However, no type material was located in that museum (pers. comm. Schillhammer 2018).

18 specimens from a single location in Germany (Table 1). Morphological measurements were done on specimens from Germany (7). The average results are shown in Fig. 2.

This species can be diagnosed from morphologically similar Cryphalus in Europe by the combination of size (usually > 1.93 mm), the broadness (elytral width is 0.9–1 mm), interstrial setae on the elytral declivity short (< 0.05 mm), the penis body ~ 0.55 mm in length (Fig. 14B–E).

Figure 14. 

Cryphalus intermedius A distribution B lateral and dorsal view C aedeagus D SEM, specimen from Dresden, Germany E SEM (43× magnification), specimen from Dresden, Germany.

Length 1.83–2.10 mm, average size 1.98 mm. Proportions: 2.10× as long as wide, elytra 1.29× as long as wide, elytra 1.70× longer than pronotum. Antennae: club with three procurved sutures marked by coarse and long setae. Funiculus with four antennomeres (including pedicel). Pronotum: dark brown to black on both slope and disc. Profile anterior to summit rounded, wider in line with elytral margin. Anterior margin with 2–6 asperities, the outer ones usually smaller, anterior marginal asperities small, erect setae on entire lateral margins. Anterior slope with < 54 asperities, including the ones on the anterior margin. Disc ~1/4 the length of pronotum, gently sloped, weakly tuberculate surface texture with small hair-like setae. Vestiture on declivity and disc hair-like. Suture between pronotum and elytra weakly sinuate. Scutellum: with few trifurcate setae on the margin towards elytra (Fig. 14D). Elytra: usually brown to black, elytral margins equally wide. Surface smooth. Striae with rows of punctures, each puncture with a short hair-like seta, punctures visible and continues on declivity. Interstrial setae short (0.03–0.05 mm) and erect. Interstrial ground vestiture (scales) are serrated, ~ 2–3× as long as wide and translucent brown with a weak iridescence (Fig. 14B, D, E). Proventriculus: sutural teeth of irregular size, confused, in two or more longitudinal rows. Apical teeth extend laterally over the entire segment. Masticatory brush slightly < 1/2 of the proventricular length (Fig. 7).

Sexual dimorphism. Not enough specimens were available to evaluate difference between males and females, but probably the last ventrite can be used to separate males and females externally, as suggested by (Johnson et al. 2020a). Wood (1982) also suggests that the sexes of several scolytines including Cryphalus, can be separated by males having a clearly visible 8^th tergite and the females a highly reduced or absent 8^th tergite. This character was not examined.

Male. The aedeagus is probably the biggest among the European species, but due to destroyed apodemes, it was not possible to evaluate the entire length of the aedeagus. The penis body is ~ 0.55 mm, when measured in a dorsal view from the two points furthest away from each other. The penis body when seen from above (dorsally) is almost symmetrical, it is narrowest at the tip and broadens until ~ 1/4 from the base, where it slightly narrows again. Aedeagus apodemes were destroyed during extraction of the aedeagus. The tegmen is sclerotised and completes a ring around the penis body. It is well developed and has two long ventral apodemes, that are ~ 2× the length of the distance between them (Figs 5, 14C).

Larvae. Nothing is known about the characteristics of the larvae of this species.

It is known from Larix decidua Mill. (Escherich 1923; Grüne 1979; Pfeffer 1995) and Pinus (Ferrari 1867; Grüne 1979).

According to the Palearctic catalogue (Knížek 2011; Alonso-Zarazaga et al. 2023), C. intermedius is found in Europe: Austria, Czechia, France, Germany, Hungary, Italy, Liechtenstein, Poland, Romania, Slovakia, Slovenia, Switzerland, Ukraine.

The current distribution of C. intermedius is correlated with the natural range of Larix decidua. However, considering that most surrounding countries outside the natural range of L. decidua, have commercial L. decidua plantations, it is likely that C. intermedius will expand to these plantations in the future. For instance, C. intermedius is mentioned from northern Germany in the second supplement to the checklist of German beetles (Köhler 2011). It has also been collected from pine (Ferrari, 1867; Grüne 1979). Grüne (1979) mentions that it occurs in the Alps. See Fig. 14A for distribution map.

The life cycle of the species has not been described in detail. We collected pupae and newly developed adults on 8^th of July 2018 from a fallen, but still fresh Larix decidua branch near Dresden, Germany (51°04'26.4"N, 14°28'57.3"E). The number of generations has not been studied in detail, but Trédl (1908) observed newly infested larch branches in July/August and found well developed adults in the same branches in October. Similar to our observations, Trédl (1908) also found well developed adults in July. Wermelinger et al. (2002) collected 18 adult specimens in traps between mid-May and late June. The flight activity in mid-May, the newly developed adults collected in July, and Trédl’s observation of well-developed beetles in October (Trédl 1908) indicate that C. intermedius may have two generations per year, as mentioned by Pfeffer (1955).

As far as we know, there has been no reports of this species causing harm to living trees.

Several authors found that the elytra of C. intermedius is 1.33–1.36× as long as wide and that the body size is ~ 2 mm (Ferrari 1867; Grüne 1979; Pfeffer 1995; Noblecourt and Schott 2004). The seven specimens measured in this study were on average 1.98 mm in body size (1.83–2.10 mm) and elytral proportions were on average 1.32 (1.26–1.38) as long as wide.

Pfeffer′s key (1995) also mentions impressed striae posteriorly on the elytra. This character was not measured but we found it a good diagnostic character.

Destroyed during the Second World War together with C. piceae type material (see C. piceae).

We designate a neotype of Cryphalus asperatus with the express purpose of clarifying the taxonomic status. In the original description, the distribution of C. asperatus is mentioned from Upper Silesia (Poland), East Prussia (Poland/Russia), Thuringian Forest (Germany) and Harzen (Germany) and the species is mentioned from Picea Mill. (Ratzeburg, 1837). A neotype of Cryphalus asperatus (Gyllenhal, 1813) is designated (Fig. 15). It is a male collected on 18/05-2023 from a Picea abies branch collected in Czechia (Silensia) (48°58'20.9"N, 19°35'16.2"E) not far from Upper Silesia. The specimen will be stored at NHMD in the entomological collections.

Figure 15. 

Neotype of Cryphalus asperatus. Stored at NHMD in the entomological collections.

599 specimens from 8 countries in Europe (Table 1) were examined. Morphological measurements were done on 38 specimens from Romania (7), Czechia (12), Slovakia (6), Netherlands (6), and Belgium (7). The results are presented in Fig. 2.

This species can be diagnosed from similar Cryphalus in Europe by the combination of body size usually < 1.75 mm (average 1.61 mm), setae on lateral margin of pronotum clearly shorter between apex and summit compared to setae in line with summit (character 3, Fig. 1), randomly distributed asperities on pronotal declivity (< 50), interstrial setae on the elytral declivity shorter than width of second interstria, often clear elytral striation. For confident identification, extraction of male genitalia is recommended. Penis body when seen dorsally is, aside from the apex, equally broad and is almost bilateral in symmetry. The entire aedeagus ~ 0.5 mm in length (Fig. 16B–E).

Figure 16. 

Cryphalus asperatus A distribution B lateral and dorsal view C aedeagus D SEM, specimen from Calibaba, Romania E SEM (43× magnification), specimen from Calibaba, Romania.

Length 1.38–1.90 mm, average 1.61 mm. Proportions: 2.3× as long as wide, elytra 1.5× as long as wide, elytra 1.95× longer than pronotum. Antennae: club with three procurved sutures marked by long setae. Funiculus with four antennomeres (including pedicel). Pronotum: dark brown to black on both slope and disc. Profile anterior to summit triangular to rounded, slightly wider in line with summit. Anterior margin with 2–7 asperities, the outer pair usually smaller, and with erect setae in line with the summit and near apex, usually short or upwards facing in-between. Anterior slope with < 50 asperities, including the ones on the anterior margin. Disc between 1/4–1/5 the length of entire pronotum, gently sloped, weakly tuberculate surface texture with a small hair-like setae in each tubercule. Vestiture on declivity and disc hair-like. Suture between pronotum and elytra weakly sinuate. Scutellum: completely covered with trifurcate hair-like setae (Fig. 16D). Elytra: usually black or dark brown but occasionally light brown, margins parallel and straight. The curvature on the declivity regularly rounded. Surface smooth. Striae often visible as rows of punctures with a short hair-like seta arising from each puncture. Interstrial setae short (0.05–0.08 mm) and erect. Interstrial ground vestiture is serrated, ~ 2–3× as long as wide and translucent brown with a weak iridescence (Fig. 16B, D, E). Proventriculus: sutural teeth of irregular size, confused, in two or more longitudinal rows. Apical teeth extend laterally to < 2/3 of the plate. Masticatory brush slightly < 1/2 of the proventricular length (Fig. 7).

Sexual dimorphism. Males and females can be separated using the last ventrite (Fig. 11), as suggested by (Johnson et al. 2020a). Wood (1982) also suggests that the sexes of several scolytines including Cryphalus, can be separated by males having a clearly visible 8^th tergite and the females a highly reduced or absent 8^th tergite. This character was not examined. No obvious differences in tubercles or carina on the frons was noticed.

Male. The aedeagus is ~ 0.5 mm long when measured vertically (i.e., from the two points furthest away from each other). The penis body when seen from above is at the side of the apex, equally broad, and almost bilaterally symmetrical and < 0.4 mm. Aedeagus apodemes makes up ~ 35% of the entire aedeagus length when measured vertically and are more or less straight and bending downwards. The tegmen is sclerotised and completes a ring around the penis body. It is thin and has two ventral apodemes, which are ~ 1/2 the length of the distance between them. The dorsal part of the tegmen ring is narrowest in the middle (Figs 5, 16C).

Larvae. For a description of larvae see the work by Ritchie (1918) or Lekander (1968).

This species is mentioned in the literature from several conifer genera, but primarily from different Picea species (Escherich 1923; Hansen 1956; Lekander et al. 1977; Grüne 1979; Wood 1992b). In a study designed to test the specificity of bark beetles to different conifer hosts, C. asperatus was found to prefer Abies and Picea over Pinus and Cupressus (Chararas et al. 1982). Ritchie (1918) found Abies as a preferred host plant of C. asperatus. We collected C. asperatus in large numbers from monocultural Abies procera Rehder plantations in Denmark, which seem to support these data (Justesen et al. 2017; pers. obs. MJJ).

According to the Palearctic catalogue (Knížek 2011; Alonso-Zarazaga et al. 2023), C. asperatus is found in Europe: Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Belarus, Czechia, Croatia, Denmark, Estonia, Finland, France, Great Britain, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxemburg, Macedonia, Montenegro, Netherlands, Norway, Poland, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Russia: Central European Territory, North European Territory, South European Territory; North Africa: Algeria, Morocco; Asia: Japan, North Korea, Turkey, Russia: East Siberia, Far East.

The catalogue reported C. asperatus in all European countries except Portugal, Ukraine, Moldova, Albania, and Serbia. Nikulina et al. (2015) collected C. asperatus in Ukraine and Marković (2013) in Serbia. Considering the natural distribution of Picea and Abies in Albania, it is unlikely that C. asperatus is not present here as well. Studies from Finland (Voolma et al. 2004) and distribution maps from Sweden (Artportalen 2023) and Norway (Artsdatabanken 2023), show that C. asperatus is not adapted to the Arctic region. The fact that the catalogue mentions C. asperatus from Japan, North Korea, and Eastern Russia needs confirmation. Distribution records from these areas could be erroneous because of similar looking species, e.g., Cryphalus sichotensis Kurenzov, 1941, C. saltuarius or others. More comparative work on the eastern species, similar to that of Johnson et al. (2020b), is necessary to figure out the easternmost extent of C. asperatus. Our distribution map follows the note by Mandelshtam (2002) stating that C. asperatus is not found east of Altai (Mandelshtam 2002). Records of C. asperatus in Morocco and Algeria also need confirmation, especially considering the one specimen (1.28: Georgia, Tlughi) from Georgia, which is 5.6% different from the European populations (Fig. 8). A larger sampling in and around Georgia, including in-depth morphological study are needed to elucidate the relationship and establish if these specimens represent a separate species or just intraspecific variation. See distribution illustrated in Fig. 16A.

During winter C. asperatus can hibernate as adults, larvae, pupae and more rarely as eggs (Ritchie 1918; Pfeffer 1955). It hibernates underneath the bark of infested material (Ritchie 1918; pers. obs. MJJ). Flight activity can start already in March (Ritchie 1918; data from Wermelinger et al. (2002); pers. obs. MJJ). Comparable unpublished data from Denmark showed that C. asperatus became active a few weeks earlier than C. piceae. During the period from March to May C. asperatus aggregates on suitable material and mates. The males will try to mate with as many females as possible, and after mating the males will excavate a nuptial chamber. Males of C. asperatus display a very distinct preference for branch nodes, and often you find branches where only nodes are inhabited (Ritchie 1918; Justesen et al. 2017). This preference is so evident that it was mentioned in the original description by Ratzeburg (1837). The preferred material seems to be moist and shaded branches, compared to sun exposed dry branches (Ritchie 1918; pers. obs. MJJ). Compared to the other European Cryphalus species, C. asperatus can target relatively old/decomposed material but can also be found in recently fallen branches. Once the males complete their nuptial chamber, the female will lay 14–24 eggs (Ritchie 1918). The development from egg to adult is variable depending on temperature, type of material, the position of the material (sun-exposed) and the time of egg-laying (Ritchie 1918). According to Ritchie (1918) two generations per year is unlikely, but he mentions the possibility of a sister generation. Grüne (1979) and Pfeffer (1955) suggested two generations per year. In an unpublished study from Denmark, 90 Abies procera branches were cut and placed as bait in an A. procera plantation in the spring. Six branches were then collected every second week and evaluated for the presence of various life stages of C. asperatus. These results suggested one generation. Based on the above information, C. asperatus most likely has two generations under ideal conditions and only one in colder climates.

In older literature C. asperatus is described as a possible harmful pest (Eichhoff 1881; Nüßlin 1905; Bodenheimer 1958). However, as already mentioned by Ritchie (1918) and Hansen (1956), these reports seem unlikely. A recent study looking at Norway spruce seedlings weakened by transport, found C. asperatus as a potential problem (Fiala and Holuša 2021). Our observations of C. asperatus support that this species is a harmless species not able to kill or weaken trees.

Differences between C. asperatus and C. saltuarius.

The shape and size of the aedeagus is the best character to separate the two species. The penis body when seen dorsally is equally broad in C. asperatus, but broadest one quarter down from the apex and then becomes increasingly narrow towards the base in C. saltuarius. The entire aedeagus is longer (~ 0.7 mm) in C. saltuarius compared to C. asperatus (~ 0.5 mm).The size difference between C. asperatus and C. saltuarius is commonly highlighted and the following lengths were reported for C. asperatus: 1.75 mm average (Ritchie 1918), 1.2–1.7 mm (Grüne 1979; Pfeffer 1995; Noblecourt and Schott 2004), 1.2–1.8 mm (Hansen 1956), and 1.3–1.8 mm (Spessivtseff 1922). We measured 38 C. asperatus specimens and found a range of 1.38–1.90 mm but, besides one noticeably larger specimen, the remaining 37 specimens were all < 1.75 mm. The following lengths were reported for C. saltuarius: 1.5–2 mm (Spessivtseff 1922; Hansen 1956; Grüne 1979; Pfeffer 1995) and 1.5–2.2 mm (Noblecourt and Schott 2004). We measured 25 specimens of C. saltuarius to 1.73–1.98 mm, with eight specimens lying between 1.73–1.75 mm. These measurements confirm that body size often is a reliable character, but also highlights that overlap occurs.

We found that C. saltuarius specimens usually had longer and perpendicularly erect setae along the margins of pronotum (Figs 1, 17B, E), whereas most C. asperatus only had erect setae in line with the summit and near apex, and then short and sometimes upwards facing setae in-between apex and summit (Fig. 16B, E). It should be mentioned that authors have observed old C. saltuarius museum specimens lacking these setae. The scutellum of C. asperatus is covered in trifurcate hair-like setae, whereas C. saltuarius only has these hairs along the elytral margin of scutellum (Figs 16D, 17D); however, this character requires high magnification and was therefore not included in the key.

Figure 17. 

Cryphalus saltuarius A distribution B lateral and dorsal view C aedeagus D SEM, specimen from Østby, Norway E SEM (43× magnification), specimen from Østby, Norway.

Several keys mention that the striae in C. asperatus are clearer (Fig. 16B, D, E) compared to more indistinct striae in C. saltuarius (Fig. 17B, D, E) (Ritchie 1918; Spessivtseff 1922; Hansen 1956; Grüne 1979; Pfeffer 1995; Noblecourt and Schott 2004). Generally, we could confirm this tendency (Fig. 4), but nine of the 25 C. saltuarius specimens had clearer striation, which could be confused with C. asperatus specimens with less distinct striation.

Noblecourt and Schott (2004) used the shape of the elytral declivity to separate C. asperatus (regular curvature) from C. saltuarius (flattened on the declivity). Our studies also found this tendency, but with a slight overlap (Fig. 4).

Most keys include proportional differences as a good character to separate the species. Noblecourt and Schott (2004) found C. asperatus was 2.3× longer than wide and C. saltuarius 2× longer than wide. Our results (Fig. 2) showed a slight tendency of C. asperatus being comparably longer than wide, but with a very high degree of overlap between the species. Grüne (1979) and Pfeffer (1995) found that the elytra of C. asperatus was 1.5–1.57× as long as wide, whereas C. saltuarius was 1.6–1.67× as long as wide. Our measurements had a large overlap in the proportional difference of elytra. Therefore, we did not find proportions as a good character. It should be noted that we measured elytral width as in Fig. 1, across the scutellum. Measurements 1/3 down from the basal border of elytra could slightly increase the width measurements, resulting in less similar proportions.

Cryphalus saltuarius was first described by Gyllenhal in 1813, under the name Bostrichus asperatus. According to Horn et al. (1990a), Gyllenhal’s material was stored at the Zoological Museum in Uppsala. Wood (1967) located the type series originally used by Gyllenhal, at the Zoological Museum in Uppsala and designated a lectotype. Additionally, three paralectotypes were stored in the Germar collection at the Museum für Naturkunde in Berlin (Wood 1972). Pictures of type material is shown in Justesen et al. (in press A).

98 specimens from various locations in Sweden and Norway (Table 1) were examined. Morphological measurements were done on 25 specimens from Norway (20) and Sweden (5). The results are shown in Fig. 2.

This species can be distinguished from similar Cryphalus in Europe by the combination of body size usually > 1.75 mm (average 1.82 mm), randomly distributed asperities on pronotal declivity (< 54), erect interstrial setae on the elytral declivity shorter than width of second interstria, setae on lateral margin of pronotum as long or only slightly shorter between apex and summit compared to setae in line with summit (character 3, Fig. 1), often obsolete elytral striation, elytral declivity often more or less flattened. For confident identification, the male genitalia is unique, because the penis body when seen from above (dorsally) is broadest one quarter down from the apex and then becomes increasingly narrow towards the base, it is almost bilateral in symmetry. The entire aedeagus is ~ 0.7 mm in length (Fig. 17B–E).

Length 1.73–1.98 mm, average size 1.82 mm (lectotype 1.85 mm). Proportions: 2.28× as long as wide, elytra 1.46× as long as wide, elytra 1.96× longer than pronotum. Antennae: club with three procurved sutures marked by coarse and long setae. Funiculus with four antennomeres. Pronotum: dark brown to black on both slope and disc. Profile anterior to summit almost triangular but slightly rounded, slightly wider in line with summit. Anterior margin with 2–5 asperities, the outer pair usually smaller, erect setae on entire lateral margins of pronotum. Anterior slope with < 50 asperities, including the ones on the anterior margin (lectotype has 44). Disc between 1/4–1/5 the length of pronotum, gently sloped, weakly tuberculate surface texture with small hair-like setae in each tubercule. Vestiture on declivity and disc hair-like. Suture between pronotum and elytra weakly sinuate. Scutellum: small with almost no setae (Fig. 17D). Elytra: usually dark brown or black but sometimes pale brown, margins widest 2/3 down from pronotal edge. The curvature on declivity irregularly rounded. Surface smooth. Striae usually only visible as rows of short hair-like setae. Interstrial setae short (0.05–0.08 mm) and erect. Interstrial ground vestiture is serrated, ~ 2× as long as wide and translucent brown with a weak iridescence (Fig. 17 B, D, E). Proventriculus: sutural teeth of irregular size, confused, in two or more longitudinal rows. Apical teeth do not extend laterally on the plate. Masticatory brush slightly < 1/2 of the proventricular length (Fig. 7).

Sexual dimorphism. Males and females can be separated using the last ventrite (Fig. 11), as suggested by (Johnson et al. 2020a). Wood (1982) also suggests that the sexes of several scolytines including Cryphalus, can be separated by males having a clearly visible 8^th tergite and the females a highly reduced or absent 8^th tergite. This character was not examined. Females were on average slightly larger than males, 1.79 mm and 1.84 mm, respectively. No clear difference in tubercles or carina on the frons was noticed.

Male. The aedeagus is ~ 0.7 mm long when measured vertically (i.e., from the two points furthest away from each other). The penis body when seen from above (dorsally) is almost bilaterally symmetrical and is broadest 1/4 from the apex and then becomes increasingly narrow towards the base. It is > 0.4 mm. Aedeagus apodemes makes up ~ 40% of the entire aedeagus length when measured vertically, more or less straight and bending downwards. The tegmen is sclerotised and completes a ring around the penis body. It is thin and has two ventral apodemes, which are ~ 1/2 the length of the distance between them (Figs 5, 17C).

Larvae. For a description of larvae see the work by Lekander (1968).

It is mostly mentioned from various Picea species (Spessivtseff 1922; Wood 1992b; Pfeffer 1995; Peltonen and Heliövaara 1998; Wermelinger et al. 2002), but has also been mentioned on Abies, Pinus (Pfeffer 1995), and Juniperus L. (Negru 1958).

According to the catalogues (Knížek 2011; Alonso-Zarazaga et al. 2023), C. saltuarius is found in Europe: Austria, Bulgaria, Belarus, Czechia, Denmark, Estonia, Finland, France, Germany, Hungary, Italy, Liechtenstein, Montenegro, Norway, Poland, Slovakia, Sweden, Switzerland, “Caucasus”, Russia: Central European Territory, North European Territory; Asia: China: Guangxi, Sichuan, Yunnan, Russia: West and East Siberia, Far East, West Siberia.

Cryphalus saltuarius is a rather common species in the Arctic regions of Scandinavia (Lekander et al. 1977). It is often regarded as rare in central Europe (Negru 1958) and it was only recently discovered in France (Noblecourt and Schott 2004). Cryphalus saltuarius has a boreo-montane distribution (Pfeffer 1995). The species is most likely present in most mountain ranges in Europe, wherever the host species is present including, for example, countries such as Ukraine (Nikulina et al. 2015), Romania (Nitzu and Olenici 2009), and Slovenia (Jurc 2003) are not mentioned in the catalogue. According to the palearctic catalogues (Knížek 2011; Alonso-Zarazaga et al. 2023) the species is present across Russia and even in some southern provinces of China. Although Kurenzov (1941), Krivolutskaya (1996) and Yanovskij (1999) reported the species from Far East Russia, Mandelshtam (2002) did not locate any specimens to confirm these records. Like C. asperatus there is not enough information about the presence of this species in the eastern Palearctic and Caucasus. The records from the Chinese provinces are interesting if confirmed, but they may be based on misidentification of another species and need confirmation. See distribution illustrated in Fig. 17A.

There are no specific studies on the life cycle of C. saltuarius. Peltonen and Heliövaara (1998) wrote that “C. saltuarius disperses during the midsummer and breeds in spruce under thin bark, e.g., in snow-broken spruce tops, branches and smaller trees”. Lekander et al. (1977) found that C. saltuarius had a two-year generation cycle, with swarming in June and hibernation as larvae. These overwintering larvae complete their development in June the following year. The newly developed beetles then hibernate. Adults and larvae were observed in Østby, Norway on 22 October 2018 from a small Picea abies tree which fell in spring 2018. We hatched 72 specimens from a small branch sampled from the tree. In the Wermelinger et al. (2002) study, 62 specimens of C. saltuarius were caught by window traps. More than 90% of these specimens were caught between end of April and beginning of June, indicating a different life cycle than described above, possibly due to the different temperatures in central Europe or confusion with the very similar C. asperatus. Pfeffer (1955) mentions two generations per year, and only one generation in higher altitude sites.

In Lekander et al. (1977), C. saltuarius is described as a secondary pest species, which under the right conditions can attack weakened, but still living spruce trees. Probably the harmfulness of this species is like C. piceae, in that only very weakened trees are attacked. Therefore, this species should not without question, be regarded as a pest, despite being abundant in recently dead trees.

For discussion on the diagnostic characters separating C. saltuarius from C. asperatus, see remarks for the latter species.