Review of the genera of Conoderinae (Coleoptera, Curculionidae) from North America, Central America, and the Caribbean

A new seed-feeding species of Hemicolpus Heller, 1895 from south Brazil and redescription of Hemicolpus abdominalis Hustache, 1938 (Coleoptera: Curculionidae: Conoderinae)

The genus Hemicolpus Heller, 1895 (Curculionidae: Conoderinae) currently includes six species: H. cubicus (Lacordaire) (Brazil); H. heteromorphus Hustache (Brazil); H. abdominalis Hustache (Bolivia, Brazil, and Paraguay); H. costaricensis Hespenheide (Costa Rica); H. randiae Hespenheide (El Salvador and Mexico) and H. prenai Hespenheide (El Salvador and Mexico). The known species are predispersal seed predators whose larvae feed and develop within fruits of Rubiaceae. Species from Central America have been reared from the fruits of Randia L. (Rubiaceae). In contrast, the only host plant known for the South American species, H. abdominalis, is Tocoyena formosa (Cham. & Schltdl.) K. Schum. (Rubiaceae), a plant species widely distributed in the Cerrado biome, occurring from southeast to north and northeast of Brazil. Here, we describe a seventh species of Hemicolpus, H. maragatensis Sanz-Veiga, Savaris & Leivas, sp. nov., morphologically close to H. abdominalis, associated with fruits of Randia ferox (Cham. & Schltdl.) DC. in the south of Brazil. Furthermore, we designate a lectotype and provide a redescription of H. abdominalis, including additional characters to differentiate it from H. maragatensis. For both species, we provide morphological descriptions of external and internal characters, including male and female genitalia illustrations, distribution data, and notes on the biology and host plant. A barcode region of the mitochondrial DNA is also included for both species adding genetic information to the species characterization and differentiation. We also provide an identification key for the species of the genus.  

The functioning of different beetle (Coleoptera) sampling methods across altitudinal gradients in Peninsular Malaysia

Biodiversity research relies largely on knowledge about species responses to environmental gradients, assessed using some commonly applied sampling method. However, the consistency of detected responses using different sampling methods, and thus the generality of findings, has seldom been assessed in tropical ecosystems. Hence, we studied the response consistency and indicator functioning of beetle assemblages in altitudinal gradients from two mountains in Malaysia, using Malaise, light, and pitfall traps. The data were analyzed using generalized linear mixed-effects models (GLMM), non-metric multidimensional scaling (NMDS), multivariate regression trees (MRT), and indicator species analysis (IndVal). We collected 198 morpho-species of beetles representing 32 families, with a total number of 3,052 individual beetles. The richness measures generally declined with increasing altitude. The mountains differed little in terms of light and Malaise trap data but differed remarkably in pitfall-trap data. Only light traps (but not the other trap types) distinguished high from middle or low altitudes in terms of beetle richness and assemblage composition. The lower altitudes hosted about twice as many indicators as middle or high altitudes, and many species were trap-type specific in our data. These results suggest that the three sampling methods reflected the altitudinal gradient in different ways and the detection of community variation in the environment thus depends on the chosen sampling method. However, also the analytical approach appeared important, further underlining the need to use multiple methods in environmental assessments.

How mountains and elevations shape the spatial distribution of beetles in Peninsular Malaysia

This study was conducted to assess the spatial distribution of beetles in mountain ecosystems and their elevational diversity. Malaise, pitfall and light traps were used to collect beetles from nine different mountains in Malaysia from September 2014 to September 2016, where from Gunung Angsi, Gunung Belumut, Gunung Basor and Gunung Tebu samples were collected at 500 m and 1000 m (above sea level) elevations, while beetles were sampled at 500 m, 1000 m and 1500 masl from Gunung Benom, Gunung Inas, Cameron Highland, Gunung Besar Hantu and Gunung Basor. In this study, 9628 beetles belonging to 879 different species were collected with highest representation from family Staphylinidae and Carabidae. Chamah Highland had the highest beetle diversity followed by Gunung Benom, Gunung Inas, Cameron Highland, Gunung Belumut, and Gunung Basor. Chamah Highland was different to all mountains on abundance and species richness. The highest species richness was observed at 1000 m, followed by 500 m and 1500 m. We identified characteristic species associated with habitat conditions at Gunung Benoum and Gunung Inas mountains, according to INDVAL values. The beetle diversity of the sampled mountains showed multiple alpha and beta patterns according to type of mountain ecosystem and elevation, providing guidelines for the scientific community to underpin conservation efforts in Malaysia.

Phenotypic analysis of aposematic conoderine weevils (Coleoptera: Curculionidae: Conoderinae) supports the existence of three large mimicry complexes

The Conoderinae (Coleoptera: Curculionidae) are one of the most distinctive Neotropical weevil groups in behaviour and appearance, attracting numerous hypotheses regarding the evolution and function of widespread apparent mimetic convergence. Conoderines have a poorly documented natural history, and a large fraction of the diversity of the group remains undescribed, presenting challenges to their study. In this analysis, 128 species of conoderine weevils previously or herein hypothesized to belong to three mimicry complexes are analysed in the first quantitative test of conoderine mimicry. Fifteen continuous and categorical characters describing the size, shape and coloration of these weevils were analysed using non-metric multidimensional scaling while statistically testing the resulting clusters in ordination space. Three similar, putatively mimetic complexes are recognized: (1) the ‘red-eyed fly’ complex of weevils, which are hypothesized to be evasively mimetic on various species of red-eyed flies; (2) the ‘striped/spotted’ complex, composed of weevils with a brightly coloured pronotum and red to white elytral stripes or spots; and (3) the ‘shiny blue’ complex of species with iridescent blue to blue–green pronotal scales. Each of these groups covers a wide geographical distribution and has evolved independently in multiple genera, although the red-eyed fly complex appears to be both the most species rich and widely distributed phylogenetically. Groupings were found to be statistically significant, although variation within each group suggests that the similarity in appearance of species in each group could be attributable to independent convergence on different, but phenotypically similar, models. Several avenues for future research on conoderine mimicry are discussed.

Pericarpial nectary-visiting ants do not provide fruit protection against pre-dispersal seed predators regardless of ant species composition and resource availability

Extrafloral nectaries can occur in both vegetative and reproductive plant structures. In many Rubiaceae species in the Brazilian Cerrado, after corolla abscission, the floral nectary continues to secret nectar throughout fruit development originating post-floral pericarpial nectaries which commonly attract many ant species. The occurrence of such nectar secreting structures might be strategic for fruit protection against seed predators, as plants are expected to invest higher on more valuable and vulnerable parts. Here, we performed ant exclusion experiments to investigate whether the interaction with ants mediated by the pericarpial nectaries of Tocoyena formosa affects plant reproductive success by reducing the number of pre-dispersal seed predators. We also assessed whether ant protection was dependent on ant species composition and resource availability. Although most of the plants were visited by large and aggressive ant species, such as Ectatomma tuberculatum and species of the genus Camponotus, ants did not protect fruits against seed predators. Furthermore, the result of the interaction was neither related to ant species composition nor to the availability of resources. We suggest that these results may be related to the nature and behavior of the most important seed predators, like Hemicolpus abdominalis weevil which the exoskeleton toughness prevent it from being predated by most ant species. On the other hand, not explored factors, such as reward quality, local ant abundance, ant colony characteristics and/or the presence of alternative energetic sources could also account for variations in ant frequency, composition, and finally ant protective effects, highlighting the conditionality of facultative plant-ant mutualisms.