Scarabaeinae

The study of diversity gradients is a frequent approach to understand evolutionary processes that structure communities. Altitudinal gradients allow the analysis of community spatial responses to environmental fluctuations. One interesting place to study altitudinal gradients is the Andes system because of the coexistence of isolated and continuous mountain ranges. We investigated the altitudinal turnover of species in peripheral mountainous systems by analyzing the structure of dung beetle assemblages along a complete gradient in the Sierra Nevada de Santa Marta, Colombia. Seven sites ranging from 480 to 2,890 m were evaluated, using linear transects of pitfall traps. A total of 2,992 individuals and 46 species were collected. Abundance, richness, and diversity diminished with altitude, revealing significant differences among sites. Some genera appeared at certain altitudes and most species appeared at unique sites, indicating a marked altitudinal turnover. A similarity analysis demonstrated the existence of separate lowland and high mountain groups with a turnover at 1,200–1,600 m asl. We registered for the first time a species replacement between Scarabaeinae (low-lands) and Aphodiinae (highlands) in the Neotropical region. Our results largely agree with the species pattern described for Mesoamerica, although, in this case the altitudinal turnover is more evident, unveiling a transition zone between lowland and high mountain fauna elements. This result suggests an equilibrium between a weak horizontal colonization and a strong vertical turnover, that appears to be higher in isolated mountains. Future investigations with other insect groups are necessary to corroborate this altitudinal pattern in isolated mountains.

Dichotomius Hope is an American genus of Scarabaeinae comprising approximately 170 described species (Vaz-de-Mello and Nunes 2016). In Mexico, only six species are recorded:Dichotomius amplicollis (Harold), Dichotomius annae Kohlmann and Solı́s,Dichotomius colonicus (Say),Dichotomius maya Peraza and Deloya, Dichotomius satanas (Harold), and Dichotomius yucatanus (Bates), all belonging to the subgenus Dichotomius (LópezGuerrero 2005; Peraza and Deloya 2006). Several authors have cited Dichotomius centralis (Harold) in Mexico, but it has been confused with D. amplicollis (López-Guerrero 2005). Therefore, we present the first record of D. centralis in Mexico and a new Mexican state record for D. amplicollis. A potential distribution map of both species is included. Several specimens of D. centralis and D. amplicollis were selected and examined with a scanning electron microscope under high vacuum and 10 kV acceleration conditions (TOPCON, model SM510®). This revealed differences in themale genitalia as López-Guerrero (2005) proposed in his study on the Mexican fauna of Dichotomius. Dichotomius centralis has abundant, visible, and protruding setae on the apex of the parameres (Figs. 1, 2), whereas in D. amplicollis the setae are small, scarce, and not protruding (Figs. 4, 5). The sculpture of the elytra of both species is also very different (Kohlmann and Solı́s 1997; López-Guerrero 2005). Dichotomius centralis has elytral striae widened with a crenulate appearance (Fig. 3), whereas D. amplicollis has narrow elytral striae (Fig. 6). These character states are consistent in minor males and females, so they should be useful to differentiate both species. To hypothesize the potential distribution of both species, we used a maximum entropy algorithm in MaxEnt version 3.4.1 (Phillips et al. 2017). The climatic variables used as predictors in the model were obtained from the WorldClim database (Fick and Hijmans 2017). Valid distribution records of D. centralis and D. amplicollis were incorporated into an Excel spreadsheet, and the final database included 97 records, many obtained from 48 bibliographic references (see Supplementary Material). The map was prepared by using QGIS software v. 3.2.0 (QGIS Development Team 2019). The map of potential distribution indicated that the Pacific slope of Chiapas (Mexico) and Guatemala is the overlapping area of both species, which was initially indicated by López-Guerrero (2005). The same author assumes the presence of D. centralis in Belize, which is confirmed by previously unpublished records of this species at two localities in Belize (see Supplementary Material). Thus, the current

The Cañón del Sumidero National Park (PNCS) is a priority area for conservation, but there are few studies on its fauna, which evidences the need for further basic studies to produce adequate knowledge on its biodiversity. This study aimed to determine dung beetle assemblages temporal distribution, trophic preference, and daily activity patterns. We conducted samplings using baited pitfall traps in a PNCS tropical sub deciduous forest remnant, during the dry and rainy seasons between 2014 and 2015. We captured a total of 863 individuals of 20 species, 12 genera, and five tribes of Scarabaeinae. Estimators suggest that we obtained high faunistic representation (> 80%), but species richness is low compared to other regional studies. The community was characterized by a high number of rare species and few dominant species. We captured the greatest richness and abundance during rainy months, however, species composition between seasons did not differ significantly. Trophic preference was mainly generalist and we considered only four species as specialists to tapir dung. We observed a clear segregation between activity hours. Nevertheless, we determined only nine species as specialists (six nocturnal and three diurnal) and two others had generalist habits. The low diversity we found could be influenced by the constant pressure of the urban area and non-native species within the park, which alter the dung beetle assemblages. However, performing samplings for longer periods and using a wider range of resources would help us obtain more robust results and better understand species distribution patterns.

Dung beetles are among the most important insects in the Neotropics. Some species use a wide range of food sources, whereas other species are highly specialized. This study compares the use of two-primate excrement by an assemblage of dung beetles in a tropical forest in Colombia. Dung of Lagothrix lagotricha and Alouatta seniculus was used to attract beetles. A total of 32 species (47.7% of the species recorded for the area) were found on the two types of excrement studied, demonstrating that primate excrement is an important resource. The niche overlap between both feces is 27.03%, which indicates a high degree of resource specialization. Although these two primate species are found in the same areas, their diets vary greatly to permit a high degree of differentiation in beetle species. A study that includes dung of others primates would create a more complete panorama of resource overlap in the assemblage.

The taxonomy of the American Onthophagus Latreille, 1802 included in the “hirculus” group is revised, and a study of their morphology allows for the delineation of five species-complexes. Herein, we provide a diagnosis of the “hirculus” group, an illustrated key to the complexes, along with a descriptive overview of their taxonomy and geographic distribution. Onthophagus hirculus Mannerheim, 1829 is considered to be a junior synonym of O. hircus Billberg, 1815, which is here demonstrated to be a valid species name. Thus, the “hirculus” group is here renamed the “hircus” group. Furthermore, a general scheme of the genital organs of American Onthophagus is provided, including names of different anatomical parts and a brief discussion on the need for nomenclatural stability for the genitalia of scarab beetles.