Under the Cretaceous bark: Fossil evidence for the ancient origin of subcortical lifestyle of clown beetles (Coleoptera: Histeridae)

We describe three new genera and four new species of the Histeridae (Coleoptera) from the mid-Cretaceous amber in Myanmar. Platycretus muscularis Simon Pražák & Lackner gen. & sp. nov. represents the first known fossil of the subfamily Histerinae from the Cretaceous. We assign the remaining three fossils, Olexum complanatum Simon Pražák & Lackner gen. & sp. nov., Cretanapleus seideli Simon Pražák & Lackner gen. & sp. nov., and Yethiha pubescens Simon Pražák & Lackner sp. nov. to the subfamily Dendrophilinae. Platycretus muscularis and O. complanatum have adaptations typical for the subcortical lifestyle (flattened body shape, dilated protibiae), proving this life strategy existed in independent lineages of clown beetles already in the Cretaceous. We also provide a review of all Histeridae fossil species described up to date and test the phylogenetic position of all of them including the newly described ones

Factors influencing carrion communities are only partially consistent with those of deadwood necromass

Research on decomposer communities has traditionally focused on plant litter or deadwood. Even though carrion forms highly nutrient-rich necromass that enhance ecosystem heterogeneity, the factors infuencing saprophytic communities remain largely unknown. For deadwood, experiments have shown that diferent drivers determine beetles (i.e., decay stage, microclimate, and space), fungi (i.e., decay stage and tree species) and bacteria (decay stage only) assemblages. To test the hypothesis that similar factors also structure carrion communities, we sampled 29 carcasses exposed for 30 days that included Cervus elaphus (N=6), Capreolus capreolus (N=18), and Vulpes vulpes (N=5) in a mountain forest throughout decomposition. Beetles were collected with pitfall traps, while microbial communities were characterized using amplicon sequencing. Assemblages were determined with a focus from rare to dominant species using Hill numbers. With increasing focus on dominant species, the relative importance of carcass identity on beetles and space on bacteria increased, while only succession and microclimate remained relevant for fungi. For beetle and bacteria with focus on dominant species, host identity was more important than microclimate, which is in marked contrast to deadwood. We conclude that factors infuencing carrion saprophytic assemblages show some consistency, but also diferences from those of deadwood assemblages, suggesting that short-lived carrion and long-lasting deadwood both provide a resource pulse with diferent adaptions in insects and microbes. As with deadwood, a high diversity of carcass species under multiple decay stages and diferent microclimates support a diverse decomposer community.publishedVersio

Dung‐visiting beetle diversity is mainly affected by land use, while community specialization is driven by climate

Dung beetles are important actors in the self‐regulation of ecosystems by driving nutrient cycling, bioturbation, and pest suppression. Urbanization and the sprawl of agricultural areas, however, destroy natural habitats and may threaten dung beetle diversity. In addition, climate change may cause shifts in geographical distribution and community composition. We used a space‐for‐time approach to test the effects of land use and climate on α‐diversity, local community specialization (H (2)′) on dung resources, and γ‐diversity of dung‐visiting beetles. For this, we used pitfall traps baited with four different dung types at 115 study sites, distributed over a spatial extent of 300 km × 300 km and 1000 m in elevation. Study sites were established in four local land‐use types: forests, grasslands, arable sites, and settlements, embedded in near‐natural, agricultural, or urban landscapes. Our results show that abundance and species density of dung‐visiting beetles were negatively affected by agricultural land use at both spatial scales, whereas γ‐diversity at the local scale was negatively affected by settlements and on a landscape scale equally by agricultural and urban land use. Increasing precipitation diminished dung‐visiting beetle abundance, and higher temperatures reduced community specialization on dung types and γ‐diversity. These results indicate that intensive land use and high temperatures may cause a loss in dung‐visiting beetle diversity and alter community networks. A decrease in dung‐visiting beetle diversity may disturb decomposition processes at both local and landscape scales and alter ecosystem functioning, which may lead to drastic ecological and economic damage

Revision of the genus Procoryphaeus Mazur, 1984 (Coleoptera: Histeridae: Histerinae: Exosternini)

Lackner, Tomáš (2015): Revision of the genus Procoryphaeus Mazur, 1984 (Coleoptera: Histeridae: Histerinae: Exosternini). Zootaxa 4044 (2): 289-300, DOI: http://dx.doi.org/10.11646/zootaxa.4044.2.

Gnathoncus semimarginatus Bickhardt 1920

Gnathoncus semimarginatus Bickhardt, 1920 (Figs 56, 59, 60–69) Gnathoncus semimarginatus Bickhardt, 1920: 29 (original description). Gnathoncus semimarginatus: KRΥƵΗΑΝοඏඌΚιΙ +| RΕιർΗΑRƉτ (1976): 115 (keyed); MΑƵUR (1984): 103 (catalogue); MΑƵUR (1997): 215 (catalogue); MΑƵUR (2004): 92 (catalogue); MΑƵUR (2011): 176 (catalogue); LΑർΚΝΕR et al. (2015): 114 (catalogue). Type locality. ‘Shi-wan-tze’ (North India or China). Type material examined. HοΓοτΥΡΕ: ♀, mounted on a triangular mounting point, right protarsus missing, ‘Shi-wan-tze | Nord-Indien’ [written] || ‘G. semimargi- | natus m. | H. Bickhardt det. 1919’ ([printed-written] || ‘Type’ [brick-red, printed label] || ‘ HOLOTYPUS | Gnathoncus | semimarginatus | Bickhardt, 1920 | labelled by MNHUB 2008’ [red label, printed] || ‘D08-086’ [yellow, pencil-written label] (MFNB). Note. Although BιർΚΗΑRƉτ’ඌ (1920) description mentions ‘China’ as the type locality, the actual specimen bears the label ‘Nord Indien: Shi-wan-tze’ (this locality has not been located). This species was described based on a single specimen, which is the holotype by original designation. Redescription. Body (Fig. 56): PEL: 3.10 mm; APW: 1.10 mm; PPW: 2.20 mm; EL: 2.20 mm; EW: 2.60 mm. Body oval, moderately convex, slightly flattened from above, cuticle piceous black; legs, mouthparts and antennae dark brown. Head. Antennal scape (Fig. 60) somewhat thickened, lower margin carinate, with few short setae; antennal club (Fig. 61) oval, without visible articulation, entire surface covered with dense short setae, intermingled with sparse setae; sensory structures of antennal club in form of two horizontal slit-like orifices on dorsal side of club, otherwise not examined. Mouthparts: mandibles with rounded outer margin curved inwardly, acutely pointed, sub-apical tooth on inner margin very small; labrum flattened, punctate, with only very shallow median excavation; labral pits with single short seta in each pit; terminal labial palpomere elongated, its width about one-fourth of its length; mentum (Fig. 62) sub-quadrate, anterior angles slightly produced, anterior margin with shallow emargination, medially with two setae, lateral margins with two rows of short sparse ramose setae, disc of mentum glabrous; cardo of maxilla with few short setae laterally; stipes triangular, with three short setae; terminal maxillary palpomere elongated, its width about one-fourth of its length, approximately three times as long as penultimate. Clypeus (Fig. 60) large, rectangular, flattened dorsally, rounded laterally, with dense punctures separated by about their own diameter; frons with coarse round to ellipsoid punctures separated by about their own diameter; eyes convex, well visible from above. Pronotum. Pronotal sides (Fig. 56) in basal half moderately convergent anteriorly, thence strongly narrowing apically; apical angles obtuse, anterior emargination for head deep, almost straight medially; marginal pronotal stria present only on basal pronotal half (Fig. 59), thin, interrupted behind head; pronotal disc laterally covered with deep round punctation, punctures separated by about their own diameter, medially punctures become finer and sparser; scutellum very small, but visible. Elytra. Epipleuron with coarse and dense ellipsoid punctures separated by about their own diameter; marginal epipleural stria doubled, weakly impressed but complete, in punctures; marginal elytral stria well impressed, slightly carinate and in punctures, shortly continued as weakened apical elytra stria, next obliterated; humeral elytral stria weakly impressed on basal third, crossed by number of fine oblique rugae; internal subhumeral stria present medially, well impressed, rather long; elytral disc with four dorsal elytral striae I–IV, first longest, deeply impressed on basal half, carinate, weakening on apical half, reaching about two-thirds of elytral length apically, second, third and fourth striae about the same length, reaching about elytral half apically, fourth stria in deep punctures, basal end of fourth stria forms small hook, between that and sutural stria present short characteristic hooked appendix; basal end of sutural elytral stria also with small hook; sutural elytral stria very short, reaching only about one-tenth of elytral length basally, then obliterated. Elytral punctation on apical half coarse and dense, punctures separated by about their own diameter; on elytral intervals 1–3 punctation much sparser, punctures separated by several times their diameter, on fourth elytral interval punctures become microscopic and very sparse; before elytral apex punctures laterally forming tiny elongate strioles. Propygidium (Fig. 63) covered with very dense and coarse punctures separated by about half their own diameter, interspaces with alutaceous microsculpture; pygidium (Fig. 63) convex medially, covered with very coarse and dense round punctures separated by about half their own diameter, interspaces with alutaceous microsculpture. Prosternum. Anterior margin of median portion of prosternum (Fig. 64) rounded; prosternal process flat, broad, dorsally and laterally covered with coarse and dense punctures separated by about 1.5 times their diameter; carinal prosternal striae well impressed, carinate, sub-parallel on basal two-thirds, thence strongly convergent anteriorly, terminating in deep tiny doubled prosternal fovea; lateral prosternal striae very short, strongly convergent anteriorly, reaching carinal prosternal striae in apical two-thirds of prosternal process. Mesoventrite. Anterior margin of mesoventrite (Fig. 65) almost straight; marginal mesoventral stria well impressed, slightly carinate; mesoventral disc flat, covered with very coarse and dense round punctures separated about their own diameter; meso-metaventral suture very thin, straight, anterad of that present undulate, inwardly bent meso-metaventral stria; intercoxal disc of metaventrite laterad of lateral metaventral stria and before metacoxa with deep round punctures separated by about their own diameter, medially punctation becomes sparser and finer and completely disappears on short narrow area around median line. Lateral metaventral stria (Fig. 66) well impressed, carinate, straight, shortened; lateral disc of metaventrite flat, with deep ellipsoid large punctures, separated by about their own diameter; metepisternum evenly covered with much coarser and denser punctation, punctures separated by less than half their own diameter. Abdomen. Intercoxal disc of first abdominal ventrite with lateral depressions, almost completely striate laterally; surface laterally and basally covered with coarse and dense punctures, medially punctation becomes finer and sparser. Legs. Protibia (Fig. 67) slightly dilated and flattened, outer margin with five conspicuous teeth diminishing in size in proximal direction topped by minute denticles; protibial spur rather large, hooked, inserted near tarsal insertion; protarsal groove rather deep; setae of outer row sparse, regular; protibial stria carinate, complete; setae of median row dense, short; tarsal denticle single, conspicuous and thin. Posterior surface of protibia (Fig. 68) with row of widely-spaced minuscule denticles; apex of protibia with three minuscule apical denticles, posterior protibial stria complete, terminating in several inner posterior denticles; inner row of setae double, thin. Mesotibia (Fig. 69) slender, outer margin with approximately nine short denticles growing in size in proximal direction, outer row of setae regular, rather short; setae of median row microscopic; posterior mesotibial stria almost complete; mesotibial spur short and stout. Anterior face of mesotibia with dense row of rather long and thick setae near outer margin, another row of microscopic setae present medially; anterior mesotibial stria complete, terminating in several inner anterior denticles. Metatibia slenderer than mesotibia with five widely-spaced denticles on outer margin growing in size in proximal direction; anterior face of mesotibia with double row of dense regular microscopic setae; terminal metatarsomere approximately twice as long as two preceding, metatarsal claws very short, shorter than half its length. Differential diagnosis. An unusually large species (PEL= 3.10 mm), distinguished easily from all SE Asian congeners by shortened marginal pronotal stria that is completely absent on its posterior half (compare Figs 58 and 59; the name semimarginatus is very appropriate here). This species somewhat resembles G. nannetensis in its sheer size and elytral punctation but differs from it in shortened marginal pronotal stria as well as obliterated apical elytral stria. Unfortunately, the only known specimen is a female. Biology. Unknown. Distribution. Known only from the holotype, which was collected either in North India or in China.Published as part of Lackner, Tomáš, 2020, A review of Gnathoncus of Southeast Asia (Coleoptera: Histeridae: Saprininae), pp. 397-409 in Acta Entomologica Musei Nationalis Pragae 60 (1) on pages 405-408, DOI: 10.37520/aemnp.2020.24, http://zenodo.org/record/448925

On the identity of Chalcionellus orcinus and Chalcionellus libanicola (Coleoptera: Histeridae)

Lackner, Tomáš (2011): On the identity of Chalcionellus orcinus and Chalcionellus libanicola (Coleoptera: Histeridae). Acta Entomologica Musei Nationalis Pragae 51 (2): 505-515, DOI: http://doi.org/10.5281/zenodo.532886

Gnathoncus nannetensis

Gnathoncus nannetensis (Marseul, 1862) (Figs 2, 25–34, 52) Saprinus nannetensis Marseul, 1862: 499 (original description). Gnathoncus urganensis Reitter, 1896: 307 (original description) – synonymized by RΕιർΗΑRƉτ (1941): 162. Gnathoncus suturalis Ganglbauer, 1899: 380 (original description) – synonymized by MΑƵUR (1984): 104. Gnathoncus nannetensis: RΕιττΕR (1896): 308 (keyed); KRΥƵΗΑΝοඏඌΚιΙ +|RΕιർΗΑRƉτ (1976):114, 117 (keyed, redescription); MΑƵUR (1984): 105 (catalogue); ÔΗΑRΑ (1994): 215, figs 130, 131, 132, 135 (key, redescription); MΑƵUR (1997): 214 (catalogue); MΑƵUR (2004): 92 (catalogue); MΑƵUR (2011): 176 (catalogue); LΑർΚΝΕR et al. (2015): 114 (catalogue). Note. This species was very thoroughly redescribed and figured in detail by ÔΗΑRΑ (1994: 215), and the reader is referred to the redescription and detailed figures there. For the sake of better recognition of this species among others distributed in Southeast Asia, the habitus (Fig. 2) as well as pygidium (Fig. 52) and male genitalia (Figs 25–34) are reproduced herein. Differential diagnosis. In the rather shiny elytral disc, this species resembles both G. rotundatus and G. brevisternus, but differs from them in round pygidial punctures (Fig. 52) and dark-brown legs (Fig. 2). From G. semimarginatus it differs in the complete marginal pronotal stria; from G. vietnamicus in the absence of longer apical fragment of the sutural elytral stria, and from G. sechuanus in the absence of strong alutaceous microsculpture of the elytra. Biology. This species is predominantly found in bird nests, but has also been recorded in burrows of small mammals, on (mostly bird) carrion, decaying fish, animal droppings, etc. (KRΥƵΗΑΝοඏඌΚιΙ +| RΕιർΗΑRƉτ 1976). Distribution. Widespread in almost the entire Palaearctic Region; from Southeast Asia recorded from China: Guangdong (LΑർΚΝΕR et al. 2015).Published as part of Lackner, Tomáš, 2020, A review of Gnathoncus of Southeast Asia (Coleoptera: Histeridae: Saprininae), pp. 397-409 in Acta Entomologica Musei Nationalis Pragae 60 (1) on page 403, DOI: 10.37520/aemnp.2020.24, http://zenodo.org/record/448925

Afroprinus cavicola gen. et sp. n. from the Afrotropical region with notes on cave-dwelling Saprininae (Coleoptera, Histeridae)

A new genus and species from Kenya, Afroprinus cavicola is herein described and illustrated and its systematic position is discussed. By the prosternal pre-apical foveae connected by marginal prosternal stria it resembles most of the Afrotropical species of the genus Chalcionellus Reichardt, 1932, or some species of the genus Pholioxenus Reichardt, 1932 from South Africa and Namibia. Afroprinus can be distinguished from Chalcionellus chiefly by the lack of pronotal depressions and a coarsely sculptured, non-metallic dorsum; from Afrotropical species of Pholioxenus it can be most easily distinguished by the asetose pronotal hypomeron. The new taxon was discovered in a cave, but lacks obvious troglophilic adaptations. Notes on other Saprininae taxa found in caves are given. An identification key to the genera of Afrotropical Saprininae is provided