Black Elytra Research Articles

Sexual dimorphism in head size in wild burying beetles

Abstract The burying beetle (Nicrophorus vespilloides) is thought to be predominantly sexually monomorphic. Males carry an additional abdominal segment and produce pheromones, but otherwise the sexes are alike. Both sexes bear bright orange bands on their black elytra, which probably function as part of a warning display rather than in mate choice. In wild populations, the sexes do not differ in mean body size, nor in its variation. Here we describe a form of sexual size dimorphism in wild populations that has previously been overlooked. We show that males have wider heads than females, for any given pronotum width (body size), and that the scaling relationship between head width and pronotum width is hyperallometric in males, but isometric in females. We also show how absolute head width, as well as the extent of sexual dimorphism in head width, differs among seven wild populations inhabiting different woodlands that are within c.10 km of each other. We suggest that head size dimorphism is functionally related to bite force. We hypothesise that dimorphism could be due to divergent selection arising from task specialisation during biparental care, as the duties of care favoured by males are likely to require a greater bite force.

First record of the genus Sceloattalus Wittmer, 1966 (Coleoptera, Malachiidae) from China, with description of a new species.

The genus Sceloattalus Wittmer, 1966 is recorded from China for the first time. A new species, S.nigroprominens Tong & Yang, sp. nov., is described and illustrated from Xizang Autonomous Region of China. This new species is the fourth member of Sceloattalus and can be easily distinguished from others by the yellow antennae with a small black spot at apex of last antennomere, black elytra without metallic lustre, all tarsi yellow, and hind tibiae yellow to black. The generic diagnosis of Sceloattalus is resummarized. An identification key to all known species of Sceloattalus is also updated.

Photonic Amorphous I‐WP‐Like Networks Create Angle‐Independent Colors in Sternotomis virescens Longhorn Beetles

AbstractStructural color originates from the interference of light with periodic structures that feature characteristic length scales on the order of the wavelength of visible light. Long‐range order in photonic structures usually causes iridescence, and increasing disorder renders colors angle‐independent. Random disorder distributes scattering intensity over all wavelengths, producing white in the absence of absorption. Various non‐iridescent, vivid color patterns are found in Sternotomini longhorn beetles. Herein, Sternotomis virescens is investigated, where elytral scales produce a green‐blue color pattern on otherwise black elytra. Combining focused ion beam scanning electron microscopy (FIB‐SEM) tomography, ultra‐small‐angle X‐ray scattering (USAXS), structural modeling, and full‐wave optical simulations, it is found that the color originates from amorphous photonic networks based on sub‐units resembling the I‐WP unit cell, a triply‐periodic minimal surface with body‐centered‐cubic symmetry. This work provides insights into how quasi‐order produces stable colors in S. virescens longhorn beetles, highlights the advantages of volumetric imaging using FIB‐SEM tomography of porous nanostructured materials, and raises interesting questions about the formation mechanisms of amorphous structures in vivo.

Hesperopenna gilolo sp. nov., the easternmost record of the genus from Halmahera, Indonesia (Coleoptera: Chrysomelidae: Galerucinae).

Hesperopenna gilolo Bezdĕk, sp. nov. from Halmahera (Indonesia), characterized by black elytra and the peculiar shape of the median lobe of the aedeagus, is described. Color photos of the habitus, body details, and drawings of the penis are presented. The new species represents the easternmost record of the genus Hesperopenna Medvedev & Dang, 1981 and the first record of the genus in the Wallacea and Maluku archipelago.

Description of a New Species of Trapeziderus Motschulsky (Coleoptera: Staphylinidae: Staphylininae) in Korea

Trapeziderus koreanus Park and Ahn, new species is described from Korea. The new species collected under bark is similar to Trapeziderus imitator Cameron in having black elytra and a temporal carina but can be distinguished by the reddish-brown antennomere 10, the chaetotaxy of the pronotum, the incomplete basal line of male sternite VIII, and the different shape and structure of the aedeagus. A description and illustrations of the new species are provided to facilitate identification.

Redescription of the Type Species of Lithocharodes Sharp (Coleoptera: Staphylinidae: Staphylininae: Xantholinini), with Remarks on the Genus

The genus Lithocharodes was described by David Sharp in 1876 for a single species, Lithocharodes fuscipennis Sharp, from the Amazon, Brazil. For over 130 years, the species has been mentioned only in catalogs. However, recent fieldwork found it in localities ranging from northern to southern Brazil. Lithocharodes fuscipennis differs from the other species of the genus mainly by the dark brown to black elytra with the apical quarter conspicuously lighter except on the elytral suture. The male genitalia of L. fuscipennis are illustrated, sexual dimorphism is described, and remarks on the genus, including a diagnosis, are presented.

Addition to the known long-horned beetle fauna of the Bolivian Andes: A new lycid-like species of Mimolaia Bates, 1885 (Coleoptera, Cerambycidae, Lamiinae, Caliini).

Mimolaia batesi sp. nov. from Bolivian Yungas forest is described and illustrated. The new species likely displays Batesian mimicry associated with slender Lycidae species having black elytra and orange/reddish pronotum laterally.

Two new species of the genus Temnaspis Lacordaire, 1845, (Coleoptera: Chrysomeloidea: Megalopodidae) from China and Myanmar, with notes on the biology of the genus.

Two new species of the genus Temnaspis Lacordaire, 1845, family Megalopodidae, are described from China and Myanmar: Temnaspis puae Li & H.B. Liang, sp. nov., Temnaspis syringa Li & H.B. Liang, sp. nov. Biological notes are provided for Temnaspis syringa. Temnaspis flavicornis Jacoby, 1892 is redescribed and a lectotype designated. A key to species of the genus Temnaspis with black elytra in China and adjacent areas is provided.

Shine and Hide: Biological Photonic Crystals on the Wings of Weevils

ABSTRACTThe body and elytra of the diamond weevil, Entimus imperialis, is studded with numerous brightly colored scales. The scales exhibit brilliant reflections because they contain unusually large diamond-type photonic crystals. The scales are concentrated in pits on the otherwise black elytra. This framing enhances the color contrast when the weevil is observed from nearby. From a distance the diamond weevil looks green, alike green foliage. Another weevil, Eupholus cuvieri, has also scales with green reflective photonic crystals, but here the scales are arranged closely apposed on the planar elytra. Both weevils use photonic crystals for camouflage, but the display methods are different.

Brilliant camouflage : photonic crystals in the diamond weevil, Entimus imperialis

The neotropical diamond weevil, Entimus imperialis, is marked by rows of brilliant spots on the overall black elytra. The spots are concave pits with intricate patterns of structural-coloured scales, consisting of large domains of three-dimensional photonic crystals that have a diamond-type structure. Reflectance spectra measured from individual scale domains perfectly match model spectra, calculated with anatomical data and finite-difference time-domain methods. The reflections of single domains are extremely directional (observed with a point source less than 5°), but the special arrangement of the scales in the concave pits significantly broadens the angular distribution of the reflections. The resulting virtually angle-independent green coloration of the weevil closely approximates the colour of a foliaceous background. While the close-distance colourful shininess of E. imperialis may facilitate intersexual recognition, the diffuse green reflectance of the elytra when seen at long-distance provides cryptic camouflage.

Mechanical properties of elytra from Tribolium castaneum wild-type and body color mutant strains

Cuticle tanning in insects involves simultaneous cuticular pigmentation and hardening or sclerotization. The dynamic mechanical properties of the highly modified and cuticle-rich forewings (elytra) from Tribolium castaneum (red flour beetle) wild-type and body color mutant strains were investigated to relate body coloration and elytral mechanical properties. There was no statistically significant variation in the storage modulus E′ among the elytra from jet, cola, sooty and black mutants or between the mutants and the wild-type GA-1 strain: E′ averaged 5.1±0.6GPa regardless of body color. E′ is a power law function of oscillation frequency for all types. The power law exponent, n, averaged 0.032±0.001 for elytra from all genotypes except black; this small value indicated that the elytra are cross-linked. Black elytra, however, displayed a significantly larger n of 0.047±0.004 and an increased loss tangent (tanδ), suggesting that metabolic differences in the black mutant strain result in elytra that are less cross-linked and more pigmented than the other types. These results are consistent with the hypothesis that black elytra have a β-alanine-deficient and dopamine-abundant metabolism, leading to greater melanin (black pigment) production, probably at the expense of cross-linking of cuticular proteins mediated by N-β-alanyldopamine quinone.

Madaglymbus, a new genus of Malagasy endemic diving beetles and description of a highly unusual species based on morphology and DNA sequence data (Dytiscidae: Copelatinae)

Madaglymbus gen. nov. is described for ten species of Aglymbus Sharp, 1882, from Madagascar and the Comoro Islands based on their morphology and a phylogenetic analysis of DNA sequence data using Bayesian and parsimony analyses. Madaglymbus was retrieved as a well supported clade (100% posterior probability both estimating model parameters for all data combined and with different loci). Madaglymbus ruthwildae sp. nov. is described from Ankarana Special Reserve, NW Madagascar. This unusual species is characterised by four highly conspicuous snow‐white spots on the brownish black elytra, its small size, numerous strioles on the pronotum and elytra, a strong and very long anterodistal seta (but not a short spine) on male protarsomere 4, and bilobed male parameres. Copelatus gestroi Sharp, 1882, comb. nov. and C. multistriatus Nilsson, 1991, comb. nov. are transferred from the genus Aglymbus to Copelatus Erichson, 1832. The following name replacements are proposed: Copelatus neogestroi Balke, nom. nov. for Copelatus gestroi Régimbart, and Copelatus agaroensis Balke nom. nov. for Copelatus multistriatus Nilsson, comb. nov.

Thermal Adaptations of the Leaf BeetleChrysomela lapponica(Coleoptera: Chrysomelidae) to Different Climes of Central and Northern Europe

This study investigated the physiologically adaptive significance of elytral coloring and other thermal adaptations to different climes of Central and Northern Europe in a leaf beetle. Adults of Chrysomela lapponica L. differ in the coloring pattern of their red and black elytra when comparing populations from Finnish Lapland (Northern Europe) and from the Czech Republic (Central Europe). While the elytra of adults of the Czech population were bright red in color with a proportion of 51% of black marks, the relative size of the black marks of the Finnish beetle’s elytra was significantly higher (68%). When exposed to light, the dark morphs from Finland increased their body temperature within a shorter time and reached higher mean body temperatures than the lighter morphs from the Czech Republic. The walking speeds of the two different morphs did not differ at temperatures of 20, 15, and 10°C. However, at 5°C, the walking speed of the melanic beetles from Finland was significantly higher. The specific metabolic rate during overwintering of the adults was significantly higher in the Finnish morph at a temperature of 5°C compared with the Czech morph. The average and maximum temperatures during overwintering in the leaf litter layer in the Czech Republic were more variable and on average higher than under the snow cover in Finland. These results on the thermoregulation in C. lapponica are discussed with special respect to melanic elytral coloring as adaptation toward lower ambient temperatures.

Description of a New SPILODISCUS Lewis, and a Reanalysis of SPILODISCUS Phylogeny (Coleoptera: Histeridae)

The discovery of a new species of Spilodiscus Lewis in Florida prompted a reanalysis of phylogenetic relationships among the known species. Spilodiscus skelleyi new species is unusual among species of Spilodiscus in its black elytra, small size, and dentate mandibles. While S. skelleyi shares the last two of these features with the Gulf coastal S. flohri Lewis, differences in aedeagal structure and external setation argue against a close relationship between these two species. Many characters that have been considered phylogenetically informative in this group possibly are quite plastic in the course of evolution.

Catecholamines and β-alanine in the red flour beetle, Tribolium castaneum: Roles in cuticle sclerotization and melanization

Catecholamines and β-alanine titres were measured in a rust-red wild strain of the red flour beetle, Tribolium castaneum Herbst and in a mutant strain which has a black cuticle. During the first three days after adult eclosion, β-alanine and N-β- alanyldopamine (NBAD) are present in the former strain, but they are absent or very low in the latter. Dopamine is approx. 3-fold higher in the black than in the rust-red strain while N- acetyldopamine , the major catecholamine in both strains, is about two times more abundant in the black. Fully sclerotized rust-red elytra contain nearly ten times more NBAD than black elytra, while the latter have about ten times more dopamine. Injection of β-alanine into newly eclosed mutant adults rescues the rust-red phenotype. One-day and two-week-old adults of the black strain exhibit 2 to 3-fold higher levels of catechol oxidase activity than wild-type adults. Cuticle pigmentation is probably determined by the relative concentrations of catecholamines, β-alanine and catechol oxidase which are utilized for production of sclerotin and melanin. High dopamine titres appear to cause the black pigmentation through melanin synthesis while β-alanine and its dopamine conjugate NBAD are associated with the rust-red colouration.

Melanism in Adalia bipunctata L. (Col., Coccinellidae) and its Relationship to Atmospheric Pollution

The use of lichens as biological indicators of air pollution is well established (Hawksworth & Rose 1970; Gilbert 1970, 1974). In the British Isles the melanic form of the peppered moth (Biston betularia L.) also seems to be a good indicator of air pollution and the same may be true of a number of other species of Lepidoptera (Kettlewell 1973). The relationship between melanism in B. betularia and air pollution does not appear to be a simple one as this melanism is related to the amount of lichen cover on tree trunks. Thus the proportion of the melanic form of this moth in the population cannot be used as an independent measure of air pollution. The discovery of other organisms that are influenced by air pollution but not by the condition of tree trunks would be invaluable. The two-spot ladybird (Adalia bipunctata L.) in common with many other Coccinellids (Hodek 1973) is a highly polymorphic species. The various morphs are under the control of a number of alleles at a single locus, with the black morphs being dominant to the red morphs (Lus 1928). In Britain these morphs can be conveniently classified into two groups, the typicals with red elytra and two black spots and the melanics with either four (quadrimaculata) or six (sexpustulata) red spots on black elytra. Intermediate forms, which are usually heterozygous, also occur, but are uncommon. Frazer & Rothschild (1960) have shown that A. bipunctata is distasteful, has a distinctive scent and is avoided by vertebrate predators. Both shiny black and red appear to be warning colours (Kettlewell 1973), so there can be little doubt that all the morphs are warningly coloured. Birds such as rooks and tits take occasional specimens of ladybirds, but the redstart (Phoenicurus phoenicurus L.) appears to be the only bird which has been recorded as regularly eating them (Buxton 1950). In Great Britain the Redstart is a summer visitor and it is doubtful whether it is abundant enough to be an important predator. Thus it would appear that selective predation of the morphs that blend less well with their surroundings, as has been shown for Biston betularia, would not operate on Adalia bipunctata and an alternative explanation for the existence of this polymorphism must be sought. Creed (1966, 1971a) postulated that melanism in A. bipunctata is directly related to air pollution and has produced evidence to link melanic frequency with smoke levels. He suggested that some unidentified component of the polluted atmosphere was less toxic to the melanic morphs than to the typicals (Creed 1971 a) and has proposed that the species may be used as an indicator of atmospheric smoke levels (Creed 1971b, 1974). We have challenged this view (Benham, Lonsdale & Muggleton 1974) and have produced evidence

Chemical Analysis of the Defensive Scent Fluid from Progaleritina mexicana (Coleoptera: Carabidae)1

One of the more distinctive ground beetles occasionally found in Travis County, Tex., is Progaleritina mexicana (Chaudoir) whose orange-colored pronotum and velvety black elytra present a rather attractive appearance. Being very timid and retiring, this beetle is usually found secluded in moist leaves and debris but occasionally can be taken under lights at night.

STUDIES IN THE CANTHARIDAE, II (COLEOPTERA)

In 1866, Dr. J. L. LeConte described Podabrus fayi and Podabrus protensus. He compared P. fayi and Podabrus tomentosus (Say) noting the differences but failing to indicate any similarity to P. protensus. P. fayi was cited as having black elytra whereas P. protensus was described as having a long tapering neck and with the elytra blackish with the basal fifth and the outer margin as far as the middle reddish yellow, the two colors shading imperceptibly together.