Food habits of 3 myrmecophilous bug species on myrmecophytic Macaranga (Malpighiales: Euphorbiaceae) vary from herbivory to predation.

Myrmecophytes have mutualistic relationships with symbiotic ants. Although myrmecophytic Macaranga (Malpighiales: Euphorbiaceae) species are well protected by aggressive Crematogaster (Hymenoptera: Formicidae) ants, some bug species occur on the myrmecophytes. To clarify the associations of these bugs with the plants and the ants, we studied the food habits of 3 bug species, Pilophorus lambirensis Nakatani et Komatsu, 2013 (Hemiptera: Miridae: Phylinae), Phylinae sp. 1, and Arbela sp. 1 (Hemiptera: Nabidae). We conducted field observations in a Bornean rainforest. First, we located these bugs and studied their behavioral responses to the ants on Macaranga species; we then conducted stable isotope analyses. All bugs avoided direct contact with ants, but they occurred only on trees with active ants. Pilophorus lambirensis and Phylinae sp. 1 were most commonly observed on the apical parts of host trees, whereas Arbela sp. 1 was mainly in areas distant from the apical parts where ants were sparse. The stable isotope ratios indicated that Phylinae sp. 1 fed on food bodies, which are nutrient-rich spherical bodies produced by Macaranga trees on the apical parts for ants. Although the main diet of the other 2 species remains unclear, nitrogen isotopic signatures demonstrated that P. lambirensis is herbivorous, whereas Arbela sp. 1 is carnivorous. However, the distant location from ants and its isotopic signatures indicated that Arbela sp. 1 rarely fed on the ants. At least 2 mirid bug species might obtain enemy-free space in addition to the food provided by the myrmecophytes.

Phylogenetic classification and palm-inflorescence anthophily of the Colocasiomyia zeylanica species group (Diptera: Drosophilidae), with descriptions of five new species.

The zeylanica group is one of the six species groups of the anthophilic genus Colocasiomyia de Meijere in the family Drosophilidae. In addition to two known species, five morphospecies have been recognized as members of this species group but left undescribed formally. In this study, species delimitation of these putatively new species was determined by barcoding of the mitochondrial COI (cytochrome c oxydase subunit I) gene and morphological comparison. Phylogenetic relationships within the genus Colocasiomyia were inferred by a cladistic analysis of 89 morphological characters. Based on the results of these analyses, we redefined the zeylanica species group and established two subgroups within it: the zeylanica subgroup comprised of C. zeylanica, C. nepalensis, C. pinangae sp. nov., C. besaris sp. nov. and C. luciphila sp. nov., and the oligochaeta subgroup of C. oligochaeta sp. nov. and C. grimaldii sp. nov. In addition, we briefly address the anthophilic habits of drosophilid flies using palm (Arecaceae) inflorescences, especially of the zeylanica group, compiling scattered collection records from the Oriental and Papuan regions.

Taxonomic study of Bornean species of Utivarachna Kishida, 1940 (Araneae: Trachelidae), with the description of a new species.

The genus Utivarachna Kishida, 1940 currently comprises 23 species, with eight described from Borneo. We examined the type materials of the Bornean species, except for U. fukasawana Kishida, 1940, as well as newly collected specimens. As a result, we describe a new species, Utivarachna itiokai sp. nov., which belongs to the dusun-group. We also provide the first description of the female of Utivarachna ichneumon and redescribe the known Utivarachna species of Borneo.

Phylogeny, taxonomy and flower-breeding ecology of the Colocasiomyia cristata species group (Diptera: Drosophilidae), with descriptions of ten new species.

The phylogeny of the Colocasiomyia cristata species group is reconstructed as a hypothesis, based on DNA sequences of two mitochondrial and six nuclear genes and 51 morphological characters. The resulting tree splits this species group into two clades, one of which corresponds to the colocasiae subgroup. Therefore, a new species subgroup named as the cristata subgroup is established for the other clade. Within the cristata subgroup, three subclades are recognized and each of them is defined as a species complex: the cristata complex composed of five species (including three new ones: C. kinabaluana sp. nov., C. kotana sp. nov. and C. matthewsi sp. nov.), the sabahana complex of two species (C. sabahana sp. nov. and C. sarawakana sp. nov.), and the xenalocasiae complex of five species (including C. sumatrana sp. nov. and C. leucocasiae sp. nov.). There are, however, three new species (C. ecornuta sp. nov., C. grandis sp. nov. and C. vieti sp. nov.) not assigned to any species complex. In addition, breeding habits are described for four cristata-subgroup species, each of which monopolizes its specific host plant. And, data of host-plant use are compiled for all species of the cristata group from records at various localities in the Oriental and Papuan regions. The evolution of host-plant selection and sharing modes is considered by mapping host-plant genera of each species on the phylogenetic tree resulting from the present study.

Heads or tails: exaggerated morphologies in relation to the use of large bamboo internodes in two lizard beetles, Doubledaya ruficollis and Oxylanguria acutipennis (Coleoptera: Erotylidae: Languriinae).

The cavities of bamboos (Poaceae) are used by various animals. Most of the animals access these cavities either by existing cracks or by excavating bamboos with soft walls or small, thin-walled bamboos. Only a few animals excavate into the cavities of large and thick- and hard-walled internodes of mature bamboos. We studied two lizard beetle species (Coleoptera: Erotylidae: Languriinae), Doubledaya ruficollis and Oxylanguria acutipennis, that excavate into large internode cavities of recently dead mature bamboos and have morphological modifications. We observed that females of D. ruficollis used their mandibles to bore oviposition holes on Schizostachyum sp. (mean wall thickness = 3.00 mm) and O. acutipennis did so on Dendrocalamus sp. (3.37 mm) bamboos. Previous studies suggested that the markedly asymmetrical mandibles and needle-like ovipositors of females in the genus Doubledaya are adaptive traits for excavating hard-walled bamboos for oviposition. Therefore, we measured their mandibular lengths and ovipositor lengths. D. ruficollis females had greater asymmetry in the mandibles and shorter and less-sclerotized ovipositors than females of congeners using small bamboos. In contrast, O. acutipennis females had slightly asymmetrical mandibles and elongated, well-sclerotized ovipositors. Oviposition holes of D. ruficollis were cone-shaped (evenly tapering), whereas those of O. acutipennis were funnel-shaped (tube-like at the internal apex). This suggests that D. ruficollis females excavate oviposition holes using the mandibles only, and O. acutipennis females use both the mandibles and ovipositors. These differences suggest different oviposition-associated morphological specialization for using large bamboos: the extremely asymmetrical mandibles in D. ruficollis and elongated, needle-like ovipositors in O. acutipennis.

New species of the ant-mimicking genus Myrmarachne MacLeay, 1839 (Araneae: Salticidae) from Sarawak, Borneo.

The genus Myrmarachne MacLeay, 1839 (Araneae: Salticidae) is one of the most diversified salticid groups in Southeast Asia, with 23 species previously recorded from Borneo. Based on the collections accumulated from 2004 to 2014 in the Lambir Hills National Park, we herein describe six new species: M. amabilis sp. nov., M. hashimotoi sp. nov., M. lagarosoma sp. nov., M. leptosoma sp. nov., M. salaputium sp. nov. and M. tintinnabulum sp. nov. In addition, we describe the female of M. endoi Yamasaki Ahmad, 2013 for the first time. The male-female combination in M. amabilis sp. nov., M. tintinnabulum sp. nov. and M. endoi were confirmed by DNA barcoding.

A new genus and a new species of Schizomyiina (Diptera: Cecidomyiidae: Asphondyliini) inducing petiole galls on Macaranga bancana (Miq.) in Borneo, Malaysia.

We describe a gall midge Macarangamyia itiokai Elsayed Tokuda gen. n., sp. n. belonging to the subtribe Schizomyiina (Diptera: Cecidomyiidae: Asphondyliini) inducing petiole galls on Macaranga bancana (Miq.) in Lambir Hills National Park, Borneo, Malaysia. The new genus is distinguishable from all known genera of Schizomyiina by the unique dorsally-placed aedeagus slit, the short, membranous, protrusible ovipositor, with scattered strong setae ventrally and dorsally, and the presence of spiracles on all larval thoracic segments. It is compared and separated from its closely related Oriental genera of Schizomyiina.

Wide host ranges of herbivorous beetles? Insights from DNA bar coding.

There are very few studies that have investigated host-specificity among tropical herbivorous insects. Indeed, most of the trophic interactions of herbivorous insects in Southeast Asian tropical rainforests remain unknown, and whether polyphagous feeding is common in the herbivores of this ecosystem has not been determined. The present study employed DNA bar coding to reveal the trophic associations of adult leaf-chewing chrysomelid beetles in a Bornean rainforest. Plant material ingested by the adults was retrieved from the bodies of the insects, and a portion of the chloroplast rbcL sequence was then amplified from this material. The plants were identified at the family level using an existing reference database of chloroplast DNA. Our DNA-based diet analysis of eleven chrysomelid species successfully identified their host plant families and indicated that five beetle species fed on more than two families within the angiosperms, and four species fed on several families of gymnosperms and/or ferns together with multiple angiosperm families. These findings suggest that generalist chrysomelid beetles associated with ecologically and taxonomically distant plants constitute a part of the plant-insect network of the Bornean rainforest.