Scarabaeinae dung beetles from Ecuador: a catalog, nomenclatural acts, and distribution records

Taxonomic Revision of the Dichotomius mormon (Ljungh, 1799) Species Group (Coleoptera: Scarabaeidae: Scarabaeinae), with a Description of a New Species from Bolivia

Dichotomius Hope, 1838 (Coleoptera: Scarabaeidae: Scarabaeinae) is a very abundant and diverse genus of dung beetles of the New World ecosystems, with about 190 species, distributed in four subgenera. Luederwaldt (Separata Rev Mus Paul 14: 3-13 1929) proposed the division of subgenera into sections (now species groups) based mainly on characters of external morphology. Based on Luederwaldt's proposal, progress has been made in recent years in the taxonomic revision of the genus; however, inconsistencies have been found in the subgeneric division and species groups proposed by this author. Based on the external morphology and the male genital organ of the all type material and other material deposited in fifteen entomological collections, in this paper, the redefinition and taxonomic revision of the Dichotomius mormon species group is carried out. The new definition of the group and the species key are presented. Five species are included in the group: Dichotomius conicollis (Blanchard, 1846) (Bolivia), Dichotomius larseni sp. nov. (Bolivia), Dichotomius mormon (Ljungh, 1799) (Argentina, Brazil, and Paraguay), Dichotomius ohausi (Luederwaldt, 1923) (Brazil, Colombia, Ecuador, and Peru), and Dichotomius talaus (Erichson, 1847) stat. rev. (Bolivia, and Peru). The lectotypes for D. conicollis, Copris ephialtes Mannerheim, 1829, Copris nasuta Castelnau, 1840, Copris protensus Perty, 1830, D. ohausi, and D. talaus were designated. For each of the species that are included in the group, the following information is presented: taxonomic history, species' citation in published literature, description or redescription of males and females, list of material examined, photographs of the external morphology, illustrations of male genital organ and its endophallites, and distribution map.

New World dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) colonization of a recent Miocene insular territory: The case of Costa Rica

Costa Rica emerged from the seas as a new geological territory during the Miocene as an insular archipelago. It later became part of a continental area once it became a segment of Central America. Two dung beetle genera that colonized this new territory from South and North America, Canthidium and Onthophagus (Coleoptera: Scarabaeidae: Scarabaeinae), are here studied, in the first analysis of a volcanic paleo-archipelago, colonized from its emergence, and then later becoming terra firma. To assess their biodiversity distribution patterns, we analyzed the effect of biogeography, ecosystem origins, and body size on their altitudinal distribution patterns in three geographic basins of Costa Rica. Based on 32 years of collecting representing more than 158,000 specimens from 1017 localities, we undertook Generalized Linear Models of the two dung beetle genera to assess the effects of biodiversity and biogeographical distribution patterns. Canthidium and Onthophagus species ranged from 0 to 3000 m a.s.l., with an abrupt diversity decline at altitudes above 1500 m. Endemic species tended to show a higher altitudinal mean with a narrow altitudinal band distribution than non-endemic dung beetle species. Although there was a trend of decreasing species body size with the increase in altitude, such a trend depended on the distribution pattern of the species group. This possible insular-mediated endemicity mechanism has generated baffling biodiversity levels, considered the highest worldwide per unit area. Costa Rica is an expanse represented by a geographic overlap of two or more temporally disjunct areas and is not part of a natural transition zone. The effect of the insular Miocene origin of Costa Rica still pervades today, reflected by different insular syndromes shown by the dung beetle fauna. The importance of geological origins in generating biodiversity seems to have been an underrated criterion for conservation biology practices and should be considered ex officio.

A Taxonomic Revision of the Dichotomius reclinatus (Felsche, 1901) Species Group (Coleoptera: Scarabaeidae: Scarabaeinae)

The taxonomic revision of the Dichotomius reclinatus species group (Coleoptera: Scarabaeidae: Scarabaeinae: Dichotomius Hope, 1838) sensu Arias-Buriticá and Vaz-de-Mello (2019) is presented. The group comprises four species previously included in the Dichotomius buqueti species group: Dichotomius horridus (Felsche, 1911) from Brazil, French Guiana, and Suriname; Dichotomius nimuendaju (Luederwaldt, 1925) from Bolivia, Brazil, and Peru; Dichotomius quadrinodosus (Felsche, 1901) from Brazil; and Dichotomius reclinatus (Felsche, 1901) from Colombia and Ecuador. A definition of the D. reclinatus species group and an identification key are presented. In the key we included to Dichotomius camposeabrai Martínez, 1974, this species due the external morphology can be confused with the D. reclinatus species group and for the first time photographs of males and female of this species are presented. For each species of the D. reclinatus species group, the following information is provided: taxonomic history, citation of the species in published literature, redescription, list of material examined, photographs of the external morphology, illustrations of male genital organs and the endophallites, and distribution map.

Morphometric changes on dung beetle Dichotomius problematicus (Coleoptera: Scarabaeidae: Scarabaeinae) related to conversion of forest into grassland: A case of study in the Ecuadorian Amazonia

The conversion of forest into grassland can induce differentiation in the functional morphology of resilient species. To assess this effect, we have chosen a dung beetle Dichotomius problematicus, as a model species. We established 20 sampling points distributed along a transect for a forest and grassland located in the Podocarpus National Park in Ecuador. Four pit-fall traps were baited with pig feces per sample point and were left open for 48 h. We sexed and measured 13 morphological traits of 269 individuals. Nonmetric multidimensional scaling was carried out to evaluate the influence of habitat and sexual dimorphism on the traits. We applied a principal component analysis to evaluate the morphological features that best explain the differences between land use and sexual dimorphism. We used generalized linear models to evaluate the explanatory variables: habitat and sexual dimorphism with respect to morphological traits. Five traits contributed over 70% body thickness, Pronotum width, Pronotum length, Head width and Elytra length, following the results of a principal component analysis. Both habitat and sex influence traits. In the forest, the individuals are larger than grassland likely due to available resources, but in grassland, the structures in charge of the burial process head, protibia are larger, displaying a strong pronotum and possible a greater reproductive capacity given by spherecity. These patterns of changes in the size of beetles and their structures could reflect the conservation state of an ecosystem.

Taxonomic identification accuracy from BOLD and GenBank databases using over a thousand insect DNA barcodes from Colombia

Recent declines of insect populations at high rates have resulted in the need to develop a quick method to determine their diversity and to process massive data for the identification of species of highly diverse groups. A short sequence of DNA from COI is widely used for insect identification by comparing it against sequences of known species. Repositories of sequences are available online with tools that facilitate matching of the sequences of interest to a known individual. However, the performance of these tools can differ. Here we aim to assess the accuracy in identification of insect taxonomic categories from two repositories, BOLD Systems and GenBank. This was done by comparing the sequence matches between the taxonomist identification and the suggested identification from the platforms. We used 1,160 COI sequences representing eight orders of insects from Colombia. After the comparison, we reanalyzed the results from a representative subset of the data from the subfamily Scarabaeinae (Coleoptera). Overall, BOLD systems outperformed GenBank, and the performance of both engines differed by orders and other taxonomic categories (species, genus and family). Higher rates of accurate identification were obtained at family and genus levels. The accuracy was higher in BOLD for the order Coleoptera at family level, for Coleoptera and Lepidoptera at genus and species level. Other orders performed similarly in both repositories. Moreover, the Scarabaeinae subset showed that species were correctly identified only when BOLD match percentage was above 93.4% and a total of 85% of the samples were correctly assigned to a taxonomic category. These results accentuate the great potential of the identification engines to place insects accurately into their respective taxonomic categories based on DNA barcodes and highlight the reliability of BOLD Systems for insect identification in the absence of a large reference database for a highly diverse country.

Biomass yield and carbon abatement potential of banana crops (Musa spp.) in Ecuador

Banana is one of the most important agricultural products of Ecuador. It relies on intensive monoculture cropping systems with a large volume of standing biomass and large amounts of residual biomass that can be used for carbon sequestration. This study was performed (1) to quantify the yearly residual biomass generation, (2) to quantify the carbon stock of standing banana biomass, (3) to estimate the carbon sequestration potential by using the residual biomass generated yearly, and (4) to propose a biomass prediction model for banana crops in Ecuador. The study was conducted between March 2018 and January 2019 in the three main banana-producing provinces of Ecuador (Los Ríos, Guayas, and El Oro). Samples of rachis, pseudostem, leaves, and flowers from 36 banana plants of the variety Musa AAA Cavendish were taken for laboratory tests. Physical measurements such as height, circumferences, number of leaves, and weights were determined for the 36 plants. Results showed an average residue-to-product ratio of 3.79 and a country's yearly biomass generation of 2.65 Mt on a dry basis. The carbon stock of the standing biomass was estimated as 4.18 ± 1.02 Mg/ha, 5.44 ± 0.96 Mg/ha, and 5.13 ± 1.11 Mg/ha for Los Ríos, Guayas, and El Oro, respectively. The estimated carbon abatement capacity of the residual biomass is 3.92 MtCO₂/year. Three biomass estimation models were developed in Python®, using the data collected in this study and least squares fitting for exponential models of the form: Y = AXⁿ + C. The models showed good prediction capacity for Ecuadorian banana plants, with R² up to 0.85. It is expected that this study could serve as the basis for studies on developing sustainable conversion processes of banana residual biomass.

Towards a comprehensive taxonomic revision of the Neotropical dung beetle subgenus Deltochilum (Deltohyboma) Lane, 1946 (Coleoptera: Scarabaeidae: Scarabaeinae): Division into species-groups

Deltochilum Eschscholtz, 1822 is perhaps the most speciose genus of the tribe Deltochilini sensu Tarasov & Dimitrov (2016) (Scarabaeidae: Scarabaeinae) and has been traditionally divided into eight subgenera. Among them, the subgenus Deltohyboma Lane, 1946, is the most speciose with 47 species, five of which are described here (D. genieri sp. nov., D. gilli sp. nov., D. susanae sp. nov., D. bolivariensis sp. nov. and D. inesae sp. nov.), and at least 165 species still undescribed. Due to the large number of species, and for practical purposes, the subgenus is here divided into 19 species-groups, with D. inesae sp. nov. left as incertae sedis. This division into species-groups will help in the reliable identification of species and will aid in the completion of the revision of subgenus. This report is the first part of the taxonomic revision of the subgenus Deltohyboma; it is based on the examination of all type specimens and almost 9,800 specimens of which approximately 1,200, mostly males, had their genitalia studied. The 19 species-groups recognized here are based mainly on characters described for the first time for Deltohyboma, namely, the state of a) the anterior margin of the clypeus (between the clypeal teeth), b) the internal margin of hypomera, c) the ventral face of the protibia, d) the posterior margin of the metafemur, and e) several new characters resulting from the first detailed study of the aedeagus and the endophallus of the group. Diagnosis, description, geographic distribution, composition and identifications keys (for males as well as males and females) for the species-groups are provided.

The biology of Megalolaelaps colossus (Acari: Dermanyssina)

Aspects of life history and host interactions of Megalolaelaps colossus were studied in a laboratory environment. These mites appear to require a host for survival, but hosts do not survive very long in a laboratory setting, leading to a modified rearing protocol relying on regular host replacement. Specific data on phenology and incidence are reported. Direct observations on feeding, mating, transmission, and interaction with other mites could not be obtained, but indirect observations allow some hypotheses in each of these areas.