Evolution of feeding habits of sap beetles (Coleoptera: Nitidulidae) and placement of Calonecrinae

Nitidulidae includes some 4500 species under 350 genera in ten subfamilies, making it the most species-rich family in Cucujoidea. In this study, we present a phylogeny of the family based on five gene regions (COI, 28s, CAD, H3, Wingless) for 73 ingroup taxa representing nine of the ten currently recognized subfamilies of Nitidulidae, including the enigmatic subfamily Calonecrinae. Our results are consistent with a prior molecular study that recovered (i) paraphyletic Nitidulinae with the inclusion of Meligethinae and Cillaeinae and (ii) subfamilial status of Prometopiinae. The molecular phylogenetic position of Calonecrinae is recovered for the first time, as a sister taxon to Epuraeinae. Ancestral state reconstruction of feeding behaviour indicates that the stem group nitidulids were largely mycophagous with transitions to other feeding types independently derived.     

Determining the origin and age of the Westland beech (Nothofagus) gap, New Zealand, using fungus beetle genetics

The formation and maintenance of the Nothofagus beech gap in the South Island, New Zealand, has been the focus of biogeographical debate since the 1920s. We examine the historical process of gap formation by investigating the population genetics of fungus beetles: Brachynopus scutellaris (Staphylinidae) inhabits logs and is absent from the beech gap, and Hisparonia hystrix (Nitidulidae) is contiguous through the gap and is found commonly on sooty mould growing on several plant species. Both species show distinctive northern and southern haplotype distributions while H. hystrix recolonized the gap as shown by definitive mixing. B. scutellaris shows two major haplotype clades with strong geographical concordance, and unlike H. hystrix, has clearly defined lineages that can be partitioned for molecular dating. Based on coalescence dating methods, disjunct lineages of B. scutellaris indicate that the gap was formed less than 200 000 years ago. Phylogenetic imprints from both species reveal similar patterns of population divergence corresponding to recent glacial cycles, favouring a glacial explanation for the origin of the gap. Post-gap colonization by H. hystrix may have been facilitated by the spread of Leptospermum scoparium host trees to the area, and they may be better at dispersing than B. scutellaris which may be constrained by fungal host and/or microhabitat. The gap-excluded species B. scutellaris is found in both beech and podocarp-broadleaf forests flanking the Westland gap and its absence in the gap may be related to incomplete recolonization following glacial retreat. We also discuss species status and an ancient polymorphism within B. scutellaris .     

Morphology and biology of the flower‐visiting water scavenger beetle genus Rygmodus (Coleoptera: Hydrophilidae)

Hydrophilidae (water scavenger beetles) is well known as an aquatic beetle family; however, it contains ca. 1,000 secondarily terrestrial species derived from aquatic ancestors. The New Zealand endemic genus Rygmodus White is a member of the hydrophilid subfamily Cylominae, which is the early‐diverging taxon of the largest terrestrial lineage (Cylominae + Sphaeridiinae) within the Hydrophilidae. In this paper we report that Rygmodus beetles are pollen‐feeding flower visitors as adults, but aquatic predators as larvae. Based on analyses of gut contents and a summary of collecting records reported on museum specimen labels, adult Rygmodus beetles are generalists feeding on pollen of at least 13 plant families. Rygmodus adult mouthparts differ from those of other (saprophagous) hydrophilid beetles in having the simple scoop‐like apex and mola with roughly denticulate surface, resembling the morphology found in pollen‐feeding staphylinid beetles. Larvae were found along the sides of streams, under stones and in algal mats and water‐soaked moss; one collected larval specimen was identified using DNA barcoding of two molecular markers, mitochondrial cytochrome oxidase 1 (cox1) and nuclear histone 3 (H3). Larvae of two species, Rygmodus modestus and Rygmodus sp., are described in detail and illustrated; they closely resemble ambush‐type predatory larvae of the hydrophilid tribe Hydrophilini in the head morphology. Rygmodus is the only known hydrophilid beetle with adults and larvae inhabiting different environments.     

Concerted versus independent evolution and the search for multiple refugia: comparative phylogeography of four forest beetles

Phylogeographic structure and its underlying causes are not necessarily shared among community members, with important implications for using individual organisms as indicators for ecosystem evolution, such as the identification of forest refugia. We used mitochondrial DNA (cox1), Bayesian coalescent ancestral state reconstruction (implemented in BEAST), and ecological niche models (ENMs) to construct geospatial histories for four codistributed New Zealand forest beetles (Leiodidae, Nitidulidae, Staphylinidae, and Zopheridae) to examine the extent to which they have tracked environmental changes together through time. Hindcast ENMs identified potential forest refugia during the Last Glacial Maximum, whereas ancestral state reconstruction identified key geographic connections for each species, facilitating direct comparison of dispersal patterns supported by the data and the time frame in which they occurred. Well-supported geographic state transitions for each species were mostly between neighboring regions, favoring a historical scenario of stepping stone colonization of newly suitable habitat rather than long distance dispersal. No geographic state transitions were shared by all four species, but three shared multiple projected South Island refugia and recent dispersal from the southernmost refugium. In contrast, strongly supported dispersal patterns in the refugia-rich northern South Island suggest more individualistic responses to environmental change in these ecologically similar forest species.     

New species and records of Laboulbeniales from the subantarctic islands of New Zealand

Until now Rhachomyces kenodactyli Balazuc & W. Rossi has been the only species of Laboulbeniales known to occur on Coleoptera in the Bounty, Antipodes, Auckland, Campbell and Snares Islands, which lie 48° to 35° S. Four new species (Diphymyces depressus, Diphymyces leschenii, Laboulbenia subantarctica and Laboulbenia loxomeri) and five new records for the subantarctic (Cucujomyces phycophilus, Diphymyces penicillifer, Laboulbenia sp. 1, Rhachomyces sp. 1 and Teratomyces sp. 1) are reported, increasing the known number of taxa tenfold. An expanded geographic range for Rhachomyces kenodactyli is reported. A relatively high percentage (12%) of known beetle species in the subantarctic serve as hosts for Laboulbeniales. This host utilization rate is higher than that in tropical and north temperate regions. The high proportion of intertidal coleopteran taxa in the subantarctic fauna probably accounts for the greater number of host species utilized. Fungi on intertidal beetles (Omaliinae [Staphylinidae], Oopterus [Carabidae] and Kenodactylus audouini [Carabidae]) are known from many host individuals and collections, while those on terrestrial species are known from few, and in some cases, a single collection or host. The sporadic occurrence of some species encountered increases the likelihood that a few species of Laboulbeniales on Coleoptera probably remain undiscovered in the region.     

Ocellar atavism in Coleoptera: plesiomorphy or apomorphy?

Ocelli and ocellus‐like structures on the vertex of the adult head were examined in different representatives of Coleoptera and the presence of these was confirmed for the suborder Polyphaga. The presence of structures, which are likely homologous with ocelli of other insects were confirmed by semi‐thin sectioning in Hydraenidae, Staphylinidae, Derodontidae and Dermestidae. The presence of ocelli is newly recorded for a representative of Scydmaenidae (Nesuthia fijii Franz). The weakly pigmented areas on the vertex of Neopelatops (Leiodidae) lack a lens and associated nervous tissue and are referred to as pseudocelli, which may be present in other groups. The internal structure of Coleopteran ocelli is strongly simplified compared with other groups of Insecta where longitudinal retinula cells are arranged at a right angle to the cuticular surface and enclosed by a sheath of pigment cells. Such a regular arrangement is absent from all beetles examined histologically. A flattened group of cells without a rhabdom and without an enclosing layer of pigment cells is present underneath the cuticular lens. While, the infrastructure of the ocelli is more or less reduced in Coleoptera, the presence of these features in the ground‐plan of Coleoptera is dependent on the confirmation of the presence of ocelli in Archostemata (Jurodidae?) and a robust phylogenetic hypothesis for the order.     

Comparative phylogenetic analysis reveals long‐term isolation of lineages on the Three Kings Islands,New Zealand

We have used comparative phylogenetic analysis to infer the age and biogeographical origins of the Three Kings Islands insect fauna, an archipelago only 56 km off the northern tip of New Zealand. We densely sampled six insect lineages (five Coleoptera, Brachynopus latus, Brachynopus scutellaris, Tarphiomimus spp., Epistranus lawsoni, and Syrphetodes spp., and one Phasmatodea, Pseudoclitarchus sentus) throughout New Zealand and sequenced mitochondrial DNA to assess phylogenetic relationships and determine ages of haplotype lineages on the Three Kings Islands. We recovered two biogeographical patterns. The first pattern was seen in three taxa, B. latus, Syrphetodes spp., and E. lawsoni, which had sister group relationships between the Three Kings and the adjacent North Cape region at the very northern tip of New Zealand. The second pattern, inferred in P. sentus, B. scutellaris, and Tarphiomimus spp., was where Three Kings lineages had sister groups that were widespread throughout most or all of New Zealand. The divergence dates, estimated using a range of previously estimated substitution rates, ranged from as old as 24 Mya in B. scutellaris to as young as 2.24 Mya in Tarphiomimus. These results are consistent with continual emergent land on the Three Kings Ridge since at least the Miocene and a lack of land connections between the Three Kings Islands and mainland New Zealand during Pleistocene sea‐level lowering. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 361–377.