A new Peruvian species of Scybalocanthon Martínez, 1948 (Coleoptera, Scarabaeidae, Scarabaeinae, Deltochilini) and some remarkable intrapopulational variation in the endophallus of S. pinopterus (Kirsch, 1873)

Dung beetles from two sustainable-use protected forests in the Brazilian Amazon

Background

The Amazon Forest is one of the world's most biodiverse ecosystems and yet its protected areas are understudied concerning insects and other invertebrates. These organisms are essential for tropical forests due to their ecological processes, with some species being very sensitive to habitat disturbances. Dung beetles (Coleoptera, Scarabaeidae, Scarabaeinae) have been used as bioindicators for more than 30 years and were surveyed to assess the insect biodiversity of two sustainable-use forest reserves in the Brazilian Amazon.

New information

We report inventories of dung beetles from two Amazonian forest reserves in Pará State, Brazil: the Tapajós National Forest and the Carajás National Forest. Surveys were carried out with baited-pitfall traps installed in 2010, 2016, 2017 and 2019. We collected a total of 3,772 individuals from 19 genera and 96 species. We highlight the importance of Amazonian protected areas as refugia for insect biodiversity, particularly dung beetles, which contribute to many key ecosystem processes.

The evolution of Bolbites onitoides (Coleoptera: Scarabaeidae: Phanaeini): its phylogenetic significance, geographical polychromatism and the subspecies problem

The distribution of the iridescent dung beetle Bolbites onitoides can be divided, based on dorsal colouration, into a blue western-half and a red eastern-half. This has raised the question, in 1959, of whether the two colour variants could represent distinct subspecies. Having examined ~1200 specimens and evaluated the proposal under both an ontological and an operational subspecies concept, we conclude that B. onitoides should continue to be treated as a single monotypic species because: (1) two kinds of colour intermediates were found living among populations of the two main variants; (2) the distribution of the variants overlaps; (3) no other characters were seen to vary consistently in accordance with the colour variants; (4) the overall geographical pattern can be explained by phenomena other than (incipient) speciation, such as phenotypic plasticity and distinct selective regimes; and (5) colour has been extensively shown not to be a reliable indicator of speciation processes among dung beetles. By comparing our findings with other cases of polychromatism among scarabaeines, we discuss publications proposing subspecies taxa relying uniquely upon colour variants. We contend that, due to the often continuous, populational, polytopic and, several times, clinal nature of the intraspecific geographical variation, subspecies classification schemes should not be established simply to classify variation across a species range without a commitment to the reality as evolutionary entities of the taxa being proposed. The alternative stance championed by many contemporary authors to give trinomina to conspecific (meta)population lineages, in turn, may eventually prove to be adequate, but we express some of our concerns as to the feasibility of this practice. Whether these intraspecific taxa should be ranked in a Linnaean hierarchy – e.g. as subspecies – is equally an open question. We also elaborate on an evolutionary scenario where the role of the iridescence in sexual selection, as hypothesized in a previous work, may be an exaptation, not an adaptation, among the horned Phanaeina.