Stag Beetle Species Research Articles

A new species of the genus Prismognathus Motschulsky (Coleoptera: Lucanidae) from Yunnan, China

A new species of stag beetle, Prismognathus helii sp. nov., which has a distinct notch on each ultimate antennomere, is described from Yunnan Province, China. Colour plates are presented to illustrate its diagnostic characters.

Study of the influence of macro-structure and micro-structure on the mechanical properties of stag beetle upper jaw

Macrostructural control of stress distribution and microstructural influence on crack propagation is one of the strategies for obtaining high mechanical properties in stag beetle upper jaws. The maximum bending fracture force of the stag beetle upper jaw is approximately 154, 000 times the weight of the upper jaw. Here, we explore the macro and micro-structural characteristics of two stag beetle upper jaws and reveal the resulting differences in mechanical properties and enhancement mechanisms. At the macroscopic level, the elliptic and triangular cross-sections of the upper jaw of the two species of stag beetles have significant effects on the formation of cracks. The crack generated by the upper jaws with a triangular section grows slowly and deflects easily. At the microscopic level, the upper jaw of the two species is a chitin cross-layered structure, but the difference between the two adjacent fiber layers at 45° and 50° leads to different deflection paths of the cracks on the exoskeleton. The mechanical properties of the upper jaw of the two species of stag beetle were significantly different due to the interaction of macro-structure and micro-structure. In addition, a series of bionic samples with different cross-section geometries and different fiber cross angles were designed, and mechanical tests were carried out according to the macro-structure and micro-structure characteristics of the stag beetle upper jaw. The effects of cross-section geometry and fiber cross angle on the mechanical properties of bionic samples are compared and analyzed. This study provides new ideas for designing and optimizing highly loaded components in engineering. Statement of significanceThe upper jaw of the stag beetle is composed of a complex arrangement of chitin and protein fibers, providing both rigidity and flexibility. This structure is designed to withstand various mechanical stresses, including impacts and bending forces, encountered during its burrowing activities and interactions with its environment. The study of the upper jaw of the stag beetle can provide an efficient structural design for engineering components that are subjected to high loads. Understanding the relationship between structure and mechanical properties in the stag beetle upper jaw holds significant implications for biomimetic design and engineering.

First fossil record of false stag beetles (Coleoptera: Scarabaeoidea: Diphyllostomatidae): Evolutionary and biogeographical implications

The monogeneric scarabaeoid family Diphyllostomatidae contains only three extant false stag beetle species, all of which are restricted to California, USA. In this study, a fossil specimen newly found in mid-Cretaceous Kachin amber of northern Myanmar is putatively assigned to this family, here described as Prodiphyllostoma inexpectatum gen. et sp. nov. The discovery of this rare scarabaeoid as a Mesozoic amber inclusion from Myanmar is significant in consideration of the paleobiogeography and evolutionary history of this family.

Distribution of the genus Platycerus Geoffroy (Coleoptera, Lucanidae) in Italy.

Stag beetles are saproxylic species that are associated with deadwood in the larval stage and play an important role in forest ecosystem dynamics. In Italy, Platyceruscaprea and Platyceruscaraboides are two small, elusive stag beetle species, whose known distribution is often limited or referring to old records. The present contribution increases the knowledge on the Italian distribution of P.caprea and P.caraboides, adding 70% more sites when compared to previously published records. Ecological traits, especially related to the altitude-elevation distribution in Italy, are also described for these saproxylic beetles.

Phenology, sex-ratio and protandry in three stag beetle species (Lucanidae) from central Italy

ABSTRACT This study examines the annual activity patterns and variation in sex ratios across different months of the year for three Lucanidae species (Lucanus cervus, Lucanus tetraodon and Dorcus parallelipipedus) in three distinct regions of central Italy. The results reveal significant differences in the month-by-month activity patterns among the species, indicating that each species has its own unique activity pattern. Specifically, L. cervus shows activity from May to September, with the highest peak between 10 and 30 June. This species remains significantly active until the end of July. Lucanus tetraodon, on the other hand, exhibits activity from June to August, with a notable peak during the last 10 days of July. Dorcus parallelipipedus displays an extended activity phase, with peaks in the first 20 days of June and the middle of July. Interestingly, various individuals of this species were also observed in November, December and February. The prolonged activity pattern of D. parallelipipedus is primarily due to overwintering adults and overlapping generations. Both Lucanus species demonstrate clear protandry, where males dominate in the initial phase, followed by a more balanced sex ratio and even female dominance in the subsequent phase. In D. parallelipipedus, the trend in sex ratio is less apparent, likely because of overlapping generations and the survival of adults for 2–3 years. The different activity patterns observed between Lucanus species can be attributed to (1) their distinct geographical distributions, with one species better adapted to temperate climates and initiating activity earlier than the strictly Mediterranean species, and (2) a possible division of temporal niches to minimise reproductive interference, reducing the chances of interspecies encounters and cross-mating.

Genomic tools for comparative conservation genetics among three recently diverged stag beetles (Lucanus, Lucanidae)

Abstract We are witnessing a rapid decline in global biodiversity. International protocols and local conservation laws have been installed to counter such an unprecedent rate of decline. However, quantitatively evaluating how much biodiversity has been lost due to climatic and anthropogenic effects and how much biodiversity has been restored due to conservation efforts remains challenging. We applied a comparative conservation genomic approach to statistically and quantitatively address these questions using three geographical taxa from a stag beetle species complex. We found that the three sky‐island taxa formed three independently evolving units without detectable post‐divergence gene flow; furthermore, the three taxa, which have been divergent from each other since the mid‐Pleistocene, have experienced episodes of demographic decline in the past. More importantly, even though idiosyncratic anthropogenic exploitations have been hypothesised to impact the recent demographic history (<100 years) differently, we found a shared pattern of continuous decline in effective population size among the three geographical taxa. We argue that future empirical studies should include more taxa, in addition to the focal species, that may or may not be affected by the focal historical events to avoid making biased conservation plans.

Evaluation of Body Size Indicators for Morphological Analyses in Two Sister Species of Genus Dorcus (Coleoptera, Lucanidae).

The relationship between trait and body size, i.e., the scaling relationship or static allometry, is an essential concept for investigating trait size. However, usage of an inappropriate body size indicator can lead to misinterpretation of morphology. In this study, we examined several possible body size indicators in two closely related stag beetle species, Dorcus rectus and Dorcus amamianus. We raised animals in captivity and used pupal weight as a measure of true, or overall body size, and then evaluated six adult morphological traits to test whether these traits could be reliably used as body size indicators in static scaling relationship comparisons. We analyzed two comparisons, between sexes in same species and between species in same sex. We showed that the most appropriate body size indicators differ depending on the comparisons. Our results indicated that the scaling relationship of focal traits could be over- or under-estimated depending on which body size indicators are used.

Darwin’s and Wallace’s Fascinations With Oversized Morphology and the Question of Developmental Plasticity

AbstractDarwin in his book, The Descent of Man and Selection in Relation to Sex, described his fascination with a male Chiasognathus grantii Stephens (Coreptera, Lucanidae), a stag beetle species with enormous mandibles. Wallace in his book, The Malay Archipelago, recorded his enchantment with a male Euchirus longimanus L. (Coreptera, Scarabaeoidae), a ‘chafer’ species with ‘immense fore-arms’ (tibia or femora). These oversized traits have been interpreted as the results of allometry through sexual selection. Both Darwin and Wallace were aware that there was a large variation in these oversized traits intraspecifically, leading to the question of the role of variability in species-level evolution. To answer this question, I studied the variation in developmental plasticity (DP; the individual ability to react to external environment) of the stag beetles, which shows a great variation in external morphology. These observations indicated that 1) DP (measured in body length) is independent of allometry of the mandibles, 2) allometry of the mandibles had been ingrained in most members of the Family before the differentiation of DP took place, 3) DP is indirectly related to sexual selection through elongated mandibles that are used for fighting or securing the mate, as evidenced by the close correlation of DP with the mandible length, and 4) the enormous mandibles of stag beetles are the product of enlarged DP through allometry and sexual selection. From these results, I add enhanced DP as an independent element in the evolution of seemingly oversized traits seen in many beetle species.

A new species of Prosopocoilus Hope amp; Westwood, 1845 from China and Vietnam (Coleoptera: Lucanidae: Lucaninae).

A new species of stag beetle, Prosopocoilus zhuchuangi new species (Coleoptera: Lucanidae: Lucaninae) is described from China (Guizhou) and Vietnam. It is closely related to P. fulgens (Didier, 1927), sharing a fringe of dense setae in the apical 2/3 of the mesal sides of the mesotibiae and metatibiae. Diagnostic characters of the two species are illustrated and compared.

A multilocus assessment reveals two new synonymies for East Asian Cyclommatus stag beetles (Coleoptera, Lucanidae).

Cyclommatus scutellaris Möllenkamp, 1912, Cyclommatus elsae Kriesche, 1921 and Cyclommatus tamdaoensis Fujita, 2010 are East Asian stag beetle species with long-debated taxonomic relationships due to high intraspecific morphological variability. In this study, we applied multilocus phylogenetic analyses to reassess their relationships. Two mitochondrial genes (16S rDNA, COI) and two nuclear genes (28S rDNA, Wingless) were used to reconstruct the phylogeny through the Bayesian inference (BI) and Maximum Likelihood (ML) methods. Both topologies supported two clades: the clade C. scutellaris was sister to the clade (C. elsae + C. tamdaoensis) with the subclade C. tamdaoensis embedded in the subclade C. elsae. The Kimura 2-parameter (K2P) genetic distance analysis yielded a low mean value (≤0.035) among the three taxa, which was well below the minimum mean value between other Cyclommatus species (≥0.122). We also compared the accuracy and efficiency of two approaches, GMYC and ABGD, in delimitating the three lineages. The result shows that ABGD is a better approach than GMYC. Our molecular data recognizes the three species as different populations of a single species, ranging from Taiwan Island to the continent. Therefore, we propose two new junior synonyms for C. scutellaris: C. tamdaoensis, syn. nov. and C. elsaesyn. nov.

Comprehensive Analyses of the Complete Mitochondrial Genome of Figulus binodulus (Coleoptera: Lucanidae).

Figulus binodulus Waterhouse is a small stag beetle distributed in East Asia. We determined the first mitochondrial genome of F. binodulus of which is 16,261-bp long including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large noncoding region of 1,717 bp. Gene order of F. binodulus is identical to the ancestral insect mitochondrial gene order as in most other stag beetle species. All of 22 tRNAs could be shaped into typical clover-leaf structure except trnSer1. Comparative analyses of 21 Lucanidae mitochondrial genomes was conducted in aspect of their length and AT-GC ratio. Nucleotide diversities analyses provide that cox1 and cox2 in Lucanidae are less diverse than those of Scarabaeoidea. Fifty simple sequence repeats (SSRs) were identified on F. binodulus mitochondrial genome. Comparative analysis of SSRs among five mitochondrial genomes displayed similar trend along with SSR types. Figulus binodulus was sister to all other available family Lucanidae species in the phylogenetic tree.

The complete mitochondrial genome of stag beetle Lucanus cervus (Coleoptera: Lucanidae) and phylogenetic analysis.

BackgroundThe stag beetle Lucanus cervus (Coleoptera: Lucanidae) is widely distributed in Europe. Habitat loss and fragmentation has led to significant reductions in numbers of this species. In this study, we sequenced the complete mitochondrial genome of L. cervus and reconstructed phylogenetic relationships among Lucanidae using complete mitochondrial genome sequences.MethodsRaw data sequences were generated by the next generation sequencing using Illumina platform from genomic DNA of L. cervus. The mitochondrial genome was assembled by IDBA and annotated by MITOS. The aligned sequences of mitochondrial genes were partitioned using PartitionFinder 2. Phylogenetic relationships among 19 stag beetle species were constructed using Maximum Likelihood (ML) method implemented in IQ-TREE web server and Bayesian method implemented in PhyloBayes MPI 1.5a. Three scarab beetles were used as outgroups.ResultsThe complete mitochondrial genome of L. cervus is 20,109 bp in length, comprising 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNAs and a control region. The A + T content is 69.93% for the majority strand. All protein-coding genes start with the typical ATN initiation codons except for cox1, which uses AAT. Phylogenetic analyses based on ML and Bayesian methods shown consistent topologies among Lucanidae.

Dorcus tianlongi, a new species from central China (Coleoptera: Lucanidae: Lucaninae).

A new species of stag beetle, Dorcus tianlongi Wang Zhou, new species (Coleoptera: Lucanidae: Lucaninae) is described from Guizhou Province, China. It is closely related to D. liyingbingi Huang Chen, 2013 and D. mencius (Kriesche, 1935). Diagnostic characters of the three species are illustrated and compared. Dorcus mencius is for the first time recorded from Henan Province of China.

Resource Holding Potential and the Outcome of Aggressive Interactions between Paired Male Aegus chelifer chelifer (Coleoptera: Lucanidae) Stag Beetles

Interactions between male stag beetles usually involve aggressive behavior using their long mandibles as weapons to compete with rival males over females. Considerable variation exists within populations in male body size, and may affect their behavior and the outcome of male-male contests. We investigated the aggressive interactions between male Aegus chelifer chelifer, a small tropical stag beetle species. Morphological traits in relation to aggressiveness and the outcome of fights were examined in laboratory-reared beetles. The fight-engagement ratios of major and minor morph males were not significantly different and analyses revealed that the size of body parts had more effect on the fighting success than the weapon part (mandibles). The probability of winning a contest was higher in males with a larger head width (HW), and so HW was considered as the resource holding potential (RHP). No effects of the trait size on the initiation of fights or aggressive intensity was found. Relationships between the fight duration and RHP were not significantly consistent with any assessment strategies, but were close to the mutual assessment model.

A review of geographical distribution of the stag beetles in Mediterranean countries (Coleoptera: Lucanidae)

A list of recent records of stag beetles (Coleoptera Lucanidae) species occurring in Mediterranean countries is given to improve the current knowledge on their geographic distribution. The saproxylic larvae of the stag beetles are very important for forest ecosystems, and some lucanid species are included in the IUCN Red List and in several national protection lists. However, the knowledge on their distribution is rather heterogeneous for several countries and taxa because the distribution records are scattered in poorly known papers or hidden in Museum or private collections. This paper is an attempt to better understanding the distribution of the stag beetle species across the Mediterranean region, to facilitate research and conservation efforts.

Functional mechanics of beetle mandibles: Honest signaling in a sexually selected system.

Male stag beetles possess colossal mandibles, which they wield in combat to obtain access to females. As with many other sexually selected weapons, males with longer mandibles win more fights. However, variation in the functional morphology of these structures, used in male-male combat, is less well understood. In this study, mandible bite force, gape, structural strength, and potential tradeoffs are examined across a wide size range for one species of stag beetle, Cyclommatus metallifer. We found that not only does male mandible size demonstrate steep positive allometry, but the shape, relative bite force, relative gape, and safety factor of the mandibles also change with male size. Allometry in these functionally important mandibular traits suggests that larger males with larger mandibles should be better fighters, and that the mandibles can be considered an honest signal of male fighting ability. However, negative allometry in mandible structural safety factor, wing size, and flight muscle mass suggest significant costs and a possible limit on the size of the mandibles. J. Exp. Zool. 325A:3-12, 2016. © 2015 Wiley Periodicals, Inc.

Development of Seven Microsatellite Markers Using Next Generation Sequencing for the Conservation on the Korean Population of Dorcus hopei (E. Saunders, 1854) (Coleoptera, Lucanidae).

We developed microsatellite markers for genetic structural analyses of Dorcus hopei, a stag beetle species, using next generation sequencing and polymerase chain reaction (PCR)-based genotyping for regional populations. A total of 407,070,351 base pairs of genomic DNA containing >4000 microsatellite loci except AT repeats were sequenced. From 76 loci selected for primer design, 27 were polymorphic. Of these 27 markers, 10 were tested on three regional populations: two Chinese (Shichuan and Guangxi) and one Korean (Wanju). Three markers were excluded due to inconsistent amplification, genotyping errors, and Hardy-Weinberg equilibrium (HWE). By multi-locus genotyping, the allele number, observed heterozygosity and polymorphism information content of seven microsatellite loci were ranged 2‒10, 0.1333‒1.0000, and 0.1228‒0.8509, respectively. In an analysis on the genetic differentiation among regional populations including one Japanese population and one cross-breeding population, the individual colored bar-plots showed that both Chinese populations were closer to each other than to the Far East Asian populations. In Far East Asian populations, Wanju and Nirasaki populations could not be distinguished from each other because the frequency of genetic contents was very similar in some individuals of two populations. Moreover, the cross-breeding population contained all patterns of genetic contents shown in Chinese, Korean, and Japanese populations, compared with the genetic content frequency of each regional population. As a result, we examined whether the cross-breeding population might be a hybrid population, and might contain a possibility of interbreeding with Chinese populations in parental generations. Therefore, these markers will be useful for analyses of genetic diversity in populations, genetic relationships between regional populations, genetic structure analyses, and origin tests.

Antibiotic-producing bacteria from stag beetle mycangia.

The search for new antibiotics or antifungal agents is crucial for the chemotherapies of infectious diseases. The limited resource of soil bacteria makes it difficult to discover such new drug candidate. We, therefore, focused on another bacterial resource than soil bacteria, the microbial flora of insect species. In the present study, we isolated 40 strains of bacteria and fungi from the mycangia of three species of stag beetle, Dorcus hopei binodulosus, Dorcus rectus, and Dorcus titanus pilifer. We identified those species with their ribosomal DNA sequences, and revealed that Klebsiella spp. are the most frequent symbiont in the stag beetle mycangia. We examined whether these microorganisms produce antibiotics against a Gram-negative bacterium, Escherichia coli, a Gram-positive bacterium, Staphylococcus aureus, or a fungus, Cryptococcus neoformans. Culture supernatants from 33, 29, or 18 strains showed antimicrobial activity against E. coli, S. aureus, or C. neoformans, respectively. These findings suggest that bacteria present in the mycangia of stag beetles are useful resources for screening novel antibiotics.

A checklist of stag beetles (Coleoptera: Scarabaeoidea: Lucanidae) from Iran.

An updated checklist of the Lucanidae (Coleoptera) from Iran is given. New locality records are listed and some dubious distributional records are discussed. Dorcus vavrai Nonfried, 1905 is placed in synonymy with Dorcus peyronis Reiche and Saulcy, 1856 (new synonymy) The female of Lucanus xerxes Král, 2004 is described. A key for the identification of the Iranian stag beetle species is also provided and all the species are figured.

A new species of stag beetle (Coleoptera: Lucanidae) from California

A new species of stag beetle (Coleoptera: Lucanidae) from California