Kunio Araya

Phylogeny of Japanese Stag Beetles (Coleoptera: Lucanidae) Inferred from 16S mtrRNA Gene Sequences, with Reference to the Evolution of Sexual Dimorphism of Mandibles

Abstract As a first step in reconstructing the phylogeny of world stag beetles (Coleoptera: Lucanidae), phylogenetic relationships among the major members of Japanese stag beetles were explored by analyzing a sequence of 1030 nucleotides from the mitochondrial 16S ribosomal RNA (16S rRNA) gene. A total of 20 species and three additional subspecies representing 13 genera were examined to provide basic information on the phylogeny of world Lucanidae. The resultant phylogenetic tree indicates that the family Lucanidae is monophyletic, and contains two major lineages: one consists of the genera Platycerus, Aesalus, Ceruchus, and Nicagus, and the other includes Dorcus, Rhaetulus, Prosopocoilus, Aegus, Neolucanus, Prismognathus, Lucanus, Figulus, and Nigidius. Generic members of the latter lineage are further divided into the following four sublineages: i) Figulus and Nigidius; ii) Prismognathus and Lucanus; iii) Aegus and Neolucanus; and iv) Dorcus, Rhaetulus, and Prosopocoilus. These molecular phylogenetic relationships are used as a basis for a preliminary exploration of the evolution of sexual dimorphism in the shape of the mandible. The results of this investigation suggest that strong sexual dimorphism with well-developed mandibles in males evolved independently at least twice, once in the genus Aegus and once in the ancestor of the Lucanus–Prismognathus and Dorcus–Rhaetulus–Prosopocoilus clades. Alternatively, it is possible that sexual dimorphism of mandibles has undergone secondary loss in the genera Figulus and Nigidius.

Phylogeny and Biogeography of Wood-Feeding Cockroaches, Genus Salganea Stål (Blaberidae: Panesthiinae), in Southeast Asia Based on Mitochondrial DNA Sequences

Molecular phylogenetic relationships among 25 species of the wood-feeding cockroach belonging to the genus Salganea Stål (Panesthiinae; Blaberidae) in Southeast Asia were analyzed based on the DNA sequence of the complete mitochondrial cytochrome oxidase II (COII) gene. Most basal relationships among species of Salganea are poorly resolved by both neighbor-joining and nonweighted parsimony analyses, suggesting the possibility of a hard polytomy due to a rapid and potentially simultaneous radiation early in the history of the genus. For more apical relationships, however, some interesting phylogenetic relationships were recognized. The monophyly of the two species groups, morio and foveolata, the former of which is distributed mainly in the Sunda lands (containing the Malay Peninsula, Sumatra, Java, and Borneo), whereas the latter is Sulawesi endemic, was strongly supported. Based on the inferred phylogenetic patterns and recent palaeogeographic scenario for Southeast Asia, it is suggested that a radiation of Salganea species occurred in Southeast Asia presumably in the early Tertiary, and several barriers against dispersal and gene flow, such as the formation of straits or high mountains, have arisen from the middle Tertiary.

The role of doublesex in the evolution of exaggerated horns in the Japanese rhinoceros beetle

Male‐specific exaggerated horns are an evolutionary novelty and have diverged rapidly via intrasexual selection. Here, we investigated the function of the conserved sex‐determination gene doublesex (dsx) in the Japanese rhinoceros beetle (Trypoxylus dichotomus) using RNA interference (RNAi). Our results show that the sex‐specific T. dichotomus dsx isoforms have an antagonistic function for head horn formation and only the male isoform has a role for thoracic horn formation. These results indicate that the novel sex‐specific regulation of dsx during horn morphogenesis might have been the key evolutionary developmental event at the transition from sexually monomorphic to sexually dimorphic horns.

Genetic structure of Japanese populations of an ambrosia beetle, Xylosandrus germanus (Curculionidae: Scolytinae)

We examined the genetic structures of 13 Japanese populations of an ambrosia beetle, Xylosandrus germanus (Curculionidae: Scolytinae), to understand the effects of geographical barriers on the colonization dynamics of this species. The genetic structure was studied using portions of the mitochondrial cytochrome oxidase I (COI) gene. A phylogenetic analysis revealed three distinct lineages (clades A, B and C) within X. germanus. Clade A contained 21 haplotypes from all 13 populations; whereas clade B contained eight haplotypes from Hokkaido (Sapporo and Furano), Iwate and Nagano populations; and clade C contained only a single a haplotype from the Hokkaido (Furano) population. In the analysis of molecular variance (amova), the greatest amount of genetic variation was detected between populations in Hokkaido and those in Honshu and other southern islands. Between these two groups of populations, all the values of the coefficient of gene differentiation were significantly larger than zero, except for the Hokkaido (Sapporo) versus Nagano comparison. Our results confirm that for X. germanus, gene flow has been interrupted between Hokkaido and Honshu since the last glacial maximum.

Phylogenetic Analyses of Fat Body Endosymbionts Reveal Differences in Invasion Times of Blaberid Wood-feeding Cockroaches (Blaberidae: Panesthiinae) into the Japanese Archipelago

Abstract Cockroaches have endosymbiotic bacteria in their fat bodies. Recent molecular phylogenetic analyses on both hosts and endosymbionts have revealed that co-evolution has occurred throughout the history of cockroaches and termites. Co-cladogenesis was also shown among closely related taxa (woodroach genus Cryptocercus; Cryptocercidae), and thus endosymbiont data are likely to be useful for biogeographical analyses. To test the possibility of co-cladogenesis among inter- and intraspecific taxa, as well as the utility of endosymbiont data for inferring biogeographical scenarios, we analyzed rRNA genes of endosymbionts of Japanese and Taiwanese Panesthiinae (Salganea and Panesthia; Blaberidae), on which phylogenetic analyses previously had been performed based on the mitochondrial genes. Statistical analyses on the topologies inferred from both endosymbiont and host mitochondria genes showed that co-cladogenesis has occurred. The endosymbiont sequences examined appear to have evolved in a clock-like manner, and their rate of evolution based on the host fossil data showed a major difference in the time of invasion of the two Japanese genera, that is congruent with the recent analyses of their mitochondrial genes.

New species of the genus Salganea (Blattaria, Blaberidae, Panesthiinae) from Myanmar, with molecular phylogenetic analyses and notes on social structure

A new species of the genus Salganea is described from Mount Victoria, Chin State, Myanmar under the name of Salganea matsumotoi sp. nov. Morphological investigation suggests that this species belongs to the S. nigrita species group. The inferred molecular phylogenetic tree indicates that S. matsumotoi is most closely related to the taxa S. incerta, S. taiwanensis, S. gressiti and S. esakii, distributed in Thailand, Taiwan and Japan, all of which belong to the S. nigrita species group. Social structural data suggest that this species is subsocial, and in contrast to other studied species in the genus, potentially has more than one reproductive episode.

Super-Protective Child-Rearing by Japanese Bess Beetles, Cylindrocaulus patalis: Adults Provide Their Larvae with Chewed and Predigested Wood

Beetles of the family Passalidae (Coleoptera: Scarabaeoidea) are termed subsocial. The insects inhabit rotten wood as family groups consisting of the parents and their offspring. The Japanese species Cylindrocaulus patalis has the lowest fecundity among passalids because siblicide occurs among the first-instar larvae; accordingly, parental care toward the survived larva is the highest among Passalidae. To clarify the nutritional relationships between the parents and their offspring, we investigated their ability to digest three types of polysaccharides that are components of wood (cellulose and β-1,4-xylan) and fungal cell walls (β-1,3-glucan). Although carboxymethyl-cellulase activity was barely detectable, β-xylosidase, β-glucosidase, β-1,4-xylanase and β-1,3-glucanase activities were clearly detected in both adults and larvae. Because the activities of enzymes that digest β-1,3-glucan were much higher than those for degrading β-1,4-xylan, in both adults and larvae, it is concluded that they are mainly fungivorous. Furthermore, these digestive enzymatic activities in second- and third-instar larvae were much lower than they were in adults. Although all larval instars grew rapidly when fed chewed wood by their parents, larvae ceased growing and died when fed only artificially ground wood meals. We conclude that the larvae are assumed to be provided with chewed predigested wood in which β-1,3-glucan is degraded by parental enzymes.

Laboratory observation of siblicide with hatching asynchrony in an insect with parental provisioning

We report laboratory observation of siblicide with hatching asynchrony in the passalid beetle Cylindrocaulus patalis. Parents construct a breeding gallery in rotten logs and show complex care of offspring, including provisioning. Clutch sizes are extremely small, and only a single offspring is raised in a colony in each breeding season. We introduced field-collected colonies into an artificial gallery and recorded the behaviour of colony members. Eggs hatched at 2- to 10-day intervals in each colony. Fatal fighting invariably occurred among the larvae soon after hatching of the junior larva, and a single larva, usually the senior one, survived.

Reptile Diversity in Food Markets in Laos

Abstract: Wildlife is one of the most important food resources in Laos, and many species are sold at the local markets, but the fauna of the country remains poorly known. As a result of human impacts, including overharvesting for food consumption, many wild animals in Asia face imminent extinction. Our study focused on reptile species that were sold at local markets in Laos. The data were recorded in February, August, and September 2013. We found 16 reptile species in the local market: eight freshwater turtle species, Cuora amboinensis, Cyclemys oldhamii, Malayemys macrocephala, M. subtrijuga, Sacalia quadriocellata, Siebenrockiella crassicollis, Amyda ornata, and Pelodiscus sinensis, one tortoise species, Manouria impressa, four lizard species, Calotes versicolor, Physignathus cocincinus, Varanus nebulosus and V. salvator, and three snake species, Malayopython reticulatus and two species of Ptyas. Most of these reptile species are used by local people as foods. Two species are recorded for the first time from Laos or the surveyed region. Our results suggested that the cryptic diversity of the reptile fauna of Laos still exists and highlighted the importance of field surveys and conservation actions.

Phylogeography of the Asian wood-feeding cockroach Salganea raggei roth (Blattaria: Blaberidae) based on the mitochondrial coii gene

Abstract The mainland Asian species of the wood-feeding cockroach, Salganea raggei Roth, has the widest distribution range in the genus, extending from the eastern Himalayas to Taiwan. The phylogeny of S. raggei was studied in relation to its geographic distribution based on the complete mitochondrial cytochrome oxidase subunit II for 16 representatives collected from variable localities as well as the other Salganea species and outgroup taxa. The resultant phylogenetic tree showed the monophyly of S. raggei and, furthermore, revealed some intraspecific monophyletic groups for this species. It was also revealed that the ancestors of the Nepalese population (the westernmost one) separated from the others, the western Myanmar population (the second westernmost one) followed, and the remaining group split into three monophyletic groups. These results suggest that S. raggei originated around the westernmost part of the present distribution range and, thereafter, spread eastwards yielding derived populations. Preliminary calibration rates based on the COII transversion divergence suggested that the ancestors of S. raggei evolved following the collision between the Indian and Asian plates (~50 million years ago), and that each monophyletic group was formed from the middle of the Miocene to the Pliocene.