Antennal Club Research Articles

Review of Dactylosternum Wollaston, 1854 from China and Japan (Coleoptera, Hydrophilidae, Sphaeridiinae).

The species of the genus Dactylosternum Wollaston, 1854 occurring in China and Japan are reviewed. Ten species are recognized to occur in China, two of which were also recorded from Japan. Four new species are described from China: Dactylosternum nanlingensis Mai et Jia, sp. nov. (Guangdong, Jiangxi) from fungal hyphae on fallen wood, D. songxiaobini Mai et Jia, sp. nov. (Guangxi) from fallen wood with termites, D. pseudolatum Mai et Jia, sp. nov. (Guangdong, Hubei, Hunan, Jiangxi, Fujian, Hainan, Yunnan) and D. frater Mai et Jia, sp. nov. (Yunnan) from banana trees. Dactylosternum latum (Sharp, 1873) and D. salvazai Orchymont, 1925 are reported for the first time from China, and species recorded previously (D. abdominale (Fabricius, 1792), D. corbetti Balfour-Browne, 1942, D. hydrophiloides (MacLeay, 1825) and D. pui Jia, 2002) are redescribed or diagnosed. Dactylosternum abdominale (Fabricius, 1792) is confirmed to occur in Japan. Dactylosternum latum is only known from Japan based on type specimens believed to be collected in Nagasaki by G. Lewis in late 19th century; since the species was never re-collected in Japan later, its distribution in Japan seems doubtful. Dactylosternum vitalisi Orchymont, 1925 is synonymized with D. latum (Sharp, 1873), the variability of the latter species is discussed. We moreover found that the type series of D. vitalisi contains two species, with some paratypes actually belonging to D. pseudolatum Mai et Jia, sp. nov. All species of Dactylosternum living in China and Japan are diagnosed and illustrated and a key allowing their identification is provided. We infer that the compact antennal club and paralleled body form are characters related to the life inside of plant tissues, while loose antennal club and rounded body form is present in free living Dactylosternum species. The combination of characters for distinguishing Dactylosternum from other genera of Coelostomatini is also provided.

Structure and distribution of antennal sensilla in Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae).

Morphology, microstructure, and distribution of antennal sensilla were compared between female and male Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae). Lamellate antennae of P. flavescens were shown to have typical scape, pedicel, and flagellum segments. The flagellum consists of a four-segmented funicle and a three-segmented club. The lengths of their pedicel and funicle were found to be similar in females and males. Distinct sexual differences were observed in the length of lamellar segments. Nine types/subtypes of sensilla were identified on the antennae of both sexes, including Böhm sensilla, sensilla trichodea, sensilla basiconica (SB), and two subtypes for sensilla chaetica, sensilla coeloconica, and sensilla placodea each. Olfactory sensilla (e.g., SB and placodea) are mainly located on three lamellar segments of the antennal club. Variation was also seen in abundance of various types of antennal sensilla, with males possessing significantly more sensilla than females. Sensilla placodea were the most abundant, and their number in males was twice of that in females, showing a clear sexual dimorphism. The difference in the distribution of sensilla placodea might reflect their roles in sexual chemical communication.

Laemophloeus souzalimai, a new species of lined flat bark beetle (Coleoptera, Cucujoidea, Laemophloeidae) from Southeast Brazil.

Distinctive, remarkable specimens from Bauru, So Paulo state, Brazil are recognized as a new species of the genus Laemophloeus Dejean (sensu stricto), which is described and illustrated in this paper. Laemophloeus souzalimai sp. nov. is most similar to L. germaini Grouvelle and can be readily distinguished from all New World species of the genus by the dorsal color testaceous, without elytral maculae, antennal club of 6 antennomeres, genal processes anteriorly projected, male head with somewhat pedunculated eyes, and frons with a broad, V-shaped impressed line. Additionally, the preexisting key to Laemophloeus species with antennal club of 6 or more antennomeres is modified to include the new species, and new records for five Brazilian species of the genus are provided.

A New Genus and Species of Lophocateridae from Mid-Cretaceous Amber of Myanmar (Coleoptera).

Simple SummaryLophocateridae are a small family of Cleroidea and their taxonomic rank has changed several times. The fossil record of Lophocateridae from Mesozoic deposits is sparse. Here, we figure and describe a new lophocaterid fossil, Gracilenticrus burmiticus, from the mid-Cretaceous amber of Myanmar. The new taxa broaden the generic and species diversity of lophocaterids and provide additional information for understanding the early evolution of Cleroidea.A new genus and species of the cleroid family Lophocateridae are described and illustrated from the mid-Cretaceous amber of northern Myanmar. Gracilenticrus burmiticus Yu, Kolibáč & Ślipiński gen. et sp. nov. is unique among Lophocateridae in the tiny body size, frontoclypeal suture and antennal grooves absent, symmetrical antennal clubs, protrochantin reduced, tarsal claws small and widened at base. A key to the species of Mesozoic Lophocateridae is also provided. Morphological characters of the newly discovered Gracilenticrus were analyzed together with representatives of 43 extant genera of Cleroidea (broadly defined Trogossitidae) in a matrix of 91 characters. Gracilenticrus burmiticus was resolved as a member of Lophocateridae. The discovery of a diverse fauna of Lophocateridae in the mid-Cretaceous sheds a new light on the early evolution of superfamily Cleroidea.

Detection of Volatile Organic Compounds by Antennal Lamellae of a Scarab Beetle

Chemoreceptive sensilla are abundantly distributed on antennal lamellae of scarab beetles. Olfactory reception by these sensory lamellae plays a major role in feeding behaviors and sexual communication of these beetles. A new electroantennogram (EAG) recording technique is here described for evaluation of electrophysiological responses of antennal lamellae of Pseudosymmachia flavescens to sex pheromones and host plant-related compounds. EAG responses were recorded simultaneously from each lamella and the closed antennal club. All test stimuli elicited similar EAG depolarization profiles in all the three lamellae and the closed club although EAG amplitudes from the same lamella or the club varied widely among different chemical stimuli. The mid lamella tended to produce significantly greater EAG responses. EAG responses evoked by a sex pheromone component, anisole, showed a significant correlation with the density of sensilla placodea subtype 1 (SP1). However, no general patterns were obtained for correlations between the density of any test sensilla type and EAG amplitudes evoked by all the six plant volatiles. Single sensillum recordings are needed to elucidate the specific roles of these sensilla in intraspecific sexual communication and perception of host plant volatiles.

Laximicracis-a new genus of Afrotropical Micracidini beetles (Coleoptera, Scolytinae).

During the revision of the micracidine genus Afromicracis Schedl, 1959, several species with unusual features required designation of a new genus. Features separating Laximicracis Jordal gen. nov. from Afromicracis includes a broadly rounded pronotum with small granules, an elongated and suture-free antennal club, a long tuft of setae on the female antennal scapus, a bispinate procurved apicolateral margin of the meso- and metatibiae, and long spatulate setae on tibiae and femurs. The new genus includes Laximicracis latipes Jordal, sp. nov. (Kenya), and the transfer from Afromicracis of Laximicracis dubia (Schedl, 1950) (Angola, Zambia, Tanzania) and Laximicracis convexus (Schedl, 1962) (South Africa). Collection localities are characterised by small dry forest patches and thickets, collected by UV- and white-light traps.

A review of the powderpost beetle genera Xylothrips Lesne, 1901 and Calophagus Lesne, 1902 (Coleoptera: Bostrichidae: Bostrichinae: Xyloperthini)

This paper reviews the genera Xylothrips Lesne, 1901 and Calophagus Lesne, 1902, and their species, and proposes that Calophagus should be reinstated as a full genus from a subgenus of Xylothrips (contra Borowski & Węgrzynowicz 2019). The genera and their included species are diagnosed and redescribed, and a summary of information on the distribution and biology of all species is provided. The importance of characters of the antennal club and pronotum in separating the two genera is stressed. A key to the two genera and the two species of Xylothrips is provided.

A previously missing link in the evolution of dasytine soft‐winged flower beetles from Cretaceous Charentese amber (Coleoptera, Melyridae)

AbstractThe soft‐winged flower beetles are a diverse cosmopolitan family of cleroid beetles with an unresolved higher classification, the adults of which feed on nectar and pollen. The fossil record of Melyridae is sparse, with only two described fossils known from the Mesozoic. Here we describe the first representative of the family from the Mesozoic of Europe, from early Cenomanian Charentese (French) amber. Due to the opaque nature of French amber, X‐ray microtomography was used to document fine morphological details of the fossil. Protodasytes cretaceus gen. et sp. nov. possesses a unique combination of characters within the subfamily Dasytinae, which is shared by the tribes Chaetomalachiini, Dasytini, and Listrini, namely the presence of a small antennal club, tarsomere 4 slightly shorter than 3 but not distinctly narrower, symmetrical claws, and a distinct pronotal and elytral fringe. This suggests that Dasytinae had begun to diversify by the Late Cretaceous, possibly in concert with the radiation of angiosperms. The fossil record of soft‐winged flower beetles is critically reviewed, and a checklist of extinct species is provided. The fragmentary Cenozoic fossils Troglops punctatissima and Malachius vertummni are removed from the family Melyridae, and the record of Attalus lusitanicus from Eocene–Oligocene Bembridge Marls is regarded as unlikely. The potential role of Protodasytes gen. nov. and Cretaceous melyrids as pollinators of early angiosperms is discussed.

Morphological variability and teratologies in the stag beetle Lucanus cervus (Coleoptera: Lucanidae) from Romania

In the present study 423 Lucanus cervus individuals belonging to the entomological collection of the” Grigore Antipa” National Museum of Natural History (MNINGA) were checked for the presence of morphological differences and anomalies. Various malformations were identified in 16 specimens. This study also presents the first cases of bilateral symphysocery 2 + 3 and unilateral symphysocery 2 + 3 + 4 at the antennal clubs for L. cervus, as revealed by scanning electron microscopy. The teratological cases were more prevalent on the left rather than the right antenna (36.3% vs. 18.18%). The normal structural variations in L. cervus were classified as follows: different number of lamellate antennomeres of the antennal club, different number of pores on the last lamella and different shapes of the clypeus. More than 94% of the examined individuals had four antennomeres at the antennal club for both left and right antennae. The rounded shape (72%) with a uniporous sensilla (98%) of the last lamellate antennomere was the most common morph in the analysed samples. Among variations, V-shaped clypeus form was prevalent (37.3%) in L. cervus analysed males. Some structural modifications could have been caused by environmental factors producing alterations in the pupation or eclosion stages. For a better understanding of the causes of teratology and the presence of morphological changes in populations of L. cervus, further investigations are needed.

A new species of the genus <i>Glaesotropis</i> Gratshev and Zherikhin, 1995 (Coleoptera, Anthribidae) from Rovno amber

Abstract. A new fungus weevil, Glaesotropis (Electranthribus) rohdendorfi sp. nov. (Coleoptera: Anthribidae), is described from Priabonian Rovno amber. It is similar to G. (E.) zherikhini (Legalov, 2013a) but differs in the transverse carina extending to the scutellum, shorter antennomere 2, wider antennal club, more convex eyes, and larger body size. It is the first record of the subgenus Electranthribus Legalov, 2013a from Rovno amber, the first named beetle from the Olevsk amber locality, and the sixth amber species reported from the Zhytomyr region. An aggregation of glaesacarid mites Glaesacarus rhombeus (Koch and Berendt, 1854) as a syninclusion with the fungus weevil is reported for the first time (41 specimens); the possibility of the glaesacarids feeding on fungi is discussed.

Taxonomic revision of the genus Rhopalapion Schilsky, 1906 (Coleoptera, Apionidae) with description of Rhopalapion celatum n. sp. from the Turanian Region.

The genus Rhopalapion Schilsky, 1906 is revised and its name is applied to Apionidae with elongate body, elongate antennal club and strong sexual dimorphism in the length of rostrum, whose biology is related to Malvaceae belonging to the genus Alcea L., 1753. The morphological study of various populations hitherto attributed to Rhopalapion longirostre (Olivier, 1807) allowed the identification of a further species, Rhopalapion celatum n. sp. (♂♀, type locality: S-Iran: Fars Province: Pâsârgâd: vicinity tomb of Cyrus), distributed in Turkey, Armenia, Azerbaijan, Syria, Iraq, Iran, Uzbekistan, Kyrgyzstan and Kazakhstan. Lectotype (♂) of Apion longirostre Olivier, 1807 is designated. The following new combinations are proposed for the species formerly assigned to Rhopalapion: Pseudaspidapion leptorostre (Voss, 1959) n. comb. and Harpapion coelestipenne (Voss, 1962) n. comb. The genera Anacrapion Mazur, 2011 and Lopatinapion Friedman, 2013 are provisionally removed from the tribe Malvapiini Alonso-Zarazaga, 1990 and considered members of the supertribe Aspidapiitae Alonso-Zarazaga, 1990 with no tribal attribution.

SEM analysis of sensilla on the mouthparts and antennae of Asian larch bark beetle Ips subelongatus

The Asian larch bark beetle, Ips subelongatus, is a severe pest of larches in Northeastern China. The gustatory and olfactory systems of I. subelongatus play important roles in host location, mating, and feeding. In this study, we examined the types, distributions, and abundances of various sensilla associated with the mouthparts and antennae of I. subelongatus using scanning electron microscopy (SEM). On the mouthparts, five types of sensilla are present: sensilla trichodea (S.t.1–3), sensilla chaetica (S.c.1–3), sensilla basiconica (S.b.1–2), sensilla twig basiconica (S.tb.1–3), and sensilla placodea (S.p). S.t.3 are the most abundant sensilla subtype on the mouthparts in both sexes, while S.b.1 are the least abundant. Most sensilla on the mouthparts are located on the maxillae and labium, and the apex of each maxillary and labial palp carry the same sensilla subtypes (S.b.2 and S.tb.1–3). However, the total number of sensilla on the apex of each maxillary palp is higher than that on the labial palp. On the antennae, five types of sensilla are present: sensilla trichodea (S.t.1–3), sensilla chaetica (S.c.1–2), sensilla basiconica (S.b.1–3), Böhm bristles (B.b), and sensilla coeloconica (S.co). Antennal sensilla are mostly situated on the anterior surface of the antennal club, particularly on the two dense sensory bands. S.b.1 are the most abundant sensilla subtype on the antennae in both sexes, while S.t.1 are the least abundant. No sexual dimorphism in sensilla type or distribution on the mouthparts or antennae is observed between the sexes of I. subelongatus. However, S.t.3 (on mouthparts) and S.c.1 (on antennae) were significantly more abundant in males than in females, while more S.t.1 (on mouthparts) were observed in females than in males. Finally, the putative functions of each kind of sensilla with respect to their fine structures, distributions, and abundances on the mouthparts and antennae are discussed.

First record of the tribe Madarini (Coleoptera: Curculionidae) from Dominican amber

ABSTRACT A new weevil genus, Tanyrhamphis gen. nov. (type species: Tanyrhamphis rhadinoalibus sp. nov.), of the subfamily Conoderinae in the family Curculionidae, is described from Dominican amber. The new genus differs from other genera of the subtribe Madarina in the tibiae lacking an uncus and from the genus Conoproctus Lacordaire, 1865 in a more slender body, the base of the pronotum clearly narrower than the elytra, the prosternum with a rostral channel, the absence of ocular lobes, and a thicker antennal club. The specimen is the first fossil record of the tribe Madarini and the second species of Bariditae from Dominican amber.

Trihelota, a new and unusual helotid beetle genus from mid-Cretaceous Burmese amber (Coleoptera: Helotidae)

A new genus belonging to the cucujoid family Helotidae, Trihelota gen. nov., is described from mid-Cretaceous (ca.99 million years old) amber from Kachin State, northern Myanmar, containing a single species T. fulvata sp. nov. The minute fossil was documented using fluorescence microscopy and X-ray microtomography to reveal fine morphological details. Trihelota is characterised by its transverse head, antennal club about 1.5 times longer than wide, pronotum almost parallel-sided, and elytra not costate. Notably, each elytron possesses three coloured spots, a character unique within Helotidae. The new genus considerably expands the known morphological disparity of Cretaceous helotids. A keyto extinct and extant genera of the family Helotidae is provided along with a checklist of fossil species.

Two new polyphagan beetles (Tenebrionidae, Leiodidae) from lower Cenomanian amber of Myanmar

Mesozoic tenebrionid and leiodid beetles are poorly known. Here we describe Praezolodinus pilosus gen. et sp. nov. (Tenebrionidae: Zolodininae) and Cretoptomaphagus microsoma gen. et sp. nov. (Leiodidae: Cholevinae), both from mid-Cretaceous Burmese amber (ca. 99 Ma). Praezolodinus pilosus is placed in the basal group Zolodininae due to (1) galea preserved with fine and long pubescence, (2) aedeagus inverted, pimeloid type. Cretoptomaphagus microsoma is assigned to Leiodidae and included in Cholevinae based on its (1) characteristic interrupted five-segmented antennal club, and (2) cephalic configuration, with the posterodorsal contour of the exposed part of the head abutting with the anterior pronotal edge. Cretoptomaphagus microsoma is the second Cholevinae described from the Mesozoic. Its strong morphological similarity with extant members of Cholevinae makes this fossil an astonishing example of long-term morphological stasis in Coleoptera.

Morphometric based differentiation among Trichogramma spp.

Genus Trichogramma Westwood is being utilized in various biological control programme worldwide. Trichogramma spp. are egg parasitoids which lay their eggs inside the host eggs. More than 240 species are known, of which, 45 species are recorded from India. It is quite difficult to identify and differentiate among the species of Trichogramma due to smaller size. In present study, we hypothesized a methodology to identify the Trichogramma species based on potential morphometric characteristics. The males and females of five different species of Trichogramma namely, T. brassicae, T. chilotraeae, T. danaidiphaga, T. danausicida and T. dendrolimi were morphometrically analysed. A total of 33 characters in males and 27 in females were taken into consideration for morphometric identification and analysis using principal component method. It was observed that few characters of male like body length, length of flagellar hair, maximum marginal hair length of fore wing, genitalia characters including aedeagus length, distance between chelate structure and gonoforceps, and others were identified as important morphometric characters. Similarly, in females, ovipositor length, body and head length, eye width, antennal club width and number of setae in forewings were found important for taxonomic identification. Male and female of each species are clearly identified from high definition microscopic images.

Description of teratologies in two species of the genus Phyllophaga (Coleoptera: Scarabaeidae: Melolonthinae)

The aim of this work is to describe and illustrate new teratological cases in species of the genus Phyllophaga. A total of 830 specimens collected in 2013 and 2017 in Sierra Sur region of the state of Oaxaca, Mexico were reviewed. Two cases of morphological anomalies were found. The first case is a clypeal malformation in Phyllophaga dasypoda, and the second case is a bifurcated right antenna with double antennal club in Phyllophaga misteca.

Speciation in North American Junonia from a genomic perspective.

Delineating species boundaries in phylogenetic groups undergoing recent radiation is a daunting challenge akin to discretizing continuity. Here, we propose a general approach exemplified by American butterflies from the genus Junonia Hübner notorious for the variety of similar phenotypes, ease of hybridization, and the lack of consensus about their classification. We obtain whole-genome shotgun sequences of about 200 specimens. We reason that discreteness emerges from continuity by means of a small number of key players, and search for the proteins that diverged markedly between sympatric populations of different species, while keeping low polymorphism within these species. Being 0.25% of the total number, these three dozen 'speciation' proteins indeed partition pairs of Junonia populations into two clusters with a prominent break in between, while all proteins taken together fail to reveal this discontinuity. Populations with larger divergence from each other, comparable to that between two sympatric species, form the first cluster and correspond to different species. The other cluster is characterized by smaller divergence, similar to that between allopatric populations of the same species and comprise conspecific pairs. Using this method, we conclude that J. genoveva (Cramer), J. litoralis Brévignon, J. evarete (Cramer), and J. divaricata C. & R. Felder are restricted to South America. We find that six species of Junonia are present in the United States, one of which is new: Junonia stemosa Grishin, sp.n. (i), found in south Texas and phenotypically closest to J. nigrosuffusa W. Barnes & McDunnough (ii) in its dark appearance. In the pale nudum of the antennal club, these two species resemble J. zonalis C. & R. Felder (iii) from Florida and the Caribbean Islands. The pair of sister species, J. grisea Austin & J. Emmel (iv) and J. coenia Hübner (v), represent the classic west/east U.S.A. split. The mangrove feeder (as caterpillar), dark nudum J. neildi Brévignon (vi) enters south Texas as a new subspecies Junonia neildi varia Grishin ssp.n. characterized by more extensive hybridization with and introgression from J. coenia, and, as a consequence, more variable wing patterns compared with the nominal J. n. neildi in Florida. Furthermore, a new mangrove-feeding species from the Pacific Coast of Mexico is described as Junonia pacoma Grishin sp.n. Finally, genomic analysis suggests that J. nigrosuffusa may be a hybrid species formed by the ancestors of J. grisea and J. stemosa sp.n.

Three new species of Hadreule Thomson (Coleoptera: Ciidae) from the Southern Hemisphere with an identification key to world species

AbstractHadreule Thomson, 1859 is a small genus of ciid beetles, comprising three Holarctic and one Australasian species. Here, three additional species from the Southern Hemisphere are described: H. mineira sp. nov. from Southeast and Northeast Brazil, characterised by the eight‐segmented antennae and male with large abdominal sex patch; H. vivianae sp. nov. from Southeast Brazil, characterised by the elytra darker than pronotum and male with small abdominal sex patch; and H. pacifica sp. nov. from Polynesian and Micronesian islands, characterised by the third antennomere being twice as long as the fourth and the possession of a two‐segmented antennal club. A brief description and images of the presumed larva of H. pacifica sp. nov. are also provided, together with images of the presumed larva of H. mineira sp. nov. and an identification key for adults of the world species of Hadreule.

A new species of Eptacus Desbrochers des Loges, 1908 from Syria (Coleoptera: Curculionidae: Entiminae)

Eptacus cylindriclavatus sp. n. is described from Syria, compared with similar congeners, and main diagnostic characters are figured. The new species was discovered near the city of Palmyra. It is relatively easily recognizable by the shape of the antennal club and rostrum. With 16 figures.