Dichotomius globulus
Creators: name: Valois, Marcely C.
name: Silva, Fernando A. B.
name: Vaz-de-Mello, Fernando Z.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Dichotomius
Dichotomius globulus

description: Diagnosis of the
globulus species group
The globulus group belongs to the subgenus Dichotomius (Selenocopris) and its species share the following combination of characters: clypeal edge bidentate, clypeogenal junction rounded; ventral clypeal process usually coniform, if bladeshaped then process not bifurcated at apex; inner apical angle of protibia obtuse (>90°); sixth abdominal ventrite of female 2–3 times longer than the fifth; female pygidium without knobs or central emargination (Nunes and Vaz-de-Mello 2019).
Within Dichotomius (Selenocopris), species of the globulus group are here considered closely related to the species of the batesi group. All species in these two groups have medium body size (length: 11–14 mm), a single conical process on the head of both sexes, pronotum covered with ocellate punctures, posterior edges of meso and metafemora with a longitudinal groove, apex of paramera weakly sclerotised (Figure 4 (a–j)) and bent downwards, and the ME at least with a median longitudinal fold (Figure 5 (b–g)).
However, as defined here, species of the globulus group can be distinguished from the species in the batesi groups by having the following: the pronotum with regular umbilicate ocellate punctures (except for D. femoratus and D. ocellatopunctatus) (vs irregularly spaced in the batesi group); surface of elytral interstriae dull, entirely shagreened or shagreened along lateral edges (Figure 3 (g–i)) (the batesi group has the elytral interstriae smooth and finely punctate); anterior and posterior edges of metafemora almost parallel along their lengths (metafemora are slightly club-shaped in the batesi group); posterior edges of meso and metafemora with a thin longitudinal groove along their entire length (while the grooves are usually restricted to the apical half or apical third of metafemora in the batesi group); dorsal surface of paramera usually with a pre-apical longitudinal carina (as in Figure 4 (c), arrows) (while in the batesi group, the paramera have small, laterally directed teeth in the pre-apical region); medial ME slightly longer than wide (Figure 5 (b–g)), hook-like projections on the inferior part of ME widely separated from each other, not blade-shaped at apex (Figure 5 (b–g)), and ME with a feeble longitudinal fold restricted to its midline (Figure 5 (b–g)) (in species of the batesi group, the ME is twice longer than wide, the hook-like projections are close to each other and blade-shaped at the apex, and the lateral edges and the midline of ME are produced into well-developed longitudinal folds along its entire length).
Key to species of the globulus group
1 – Pronotal punctures irregularly spaced, separated by at least their diameter on disc (Figure 3 (e)) ............................................................................................................................................. 2
1’ – Pronotal punctures umbilicate, equally spaced, separated by less than their diameter on disc (as in Figure 3 (f)).................................................................................................................... 3
2 – Surface of elytral interstriae shinning at centre and shagreened along the lateral portions, near striae (Figure 3 (h), ShMicro). Clypeofrontal region of both sexes with a central knob. Male pronotum with a distinct anterior declivity at centre (Figure 1 (c)). Panama and Costa Rica .................... .................... D. femoratus Howden and Young, 1981.
2’ – Surface of elytral interstriae completely shagreened. Clypeofrontal region of both sexes lacking cephalic process or with a very low central knob (fig. 2(a) in Vaz-de-Mello and Nunes 2016). Male pronotum with a feeble anterior declivity (fig. 2(a) in Vaz-de-Mello and Nunes 2016). Known only from Venezuela ................................................. ................................................................................................ D. ocellatopunctatus (Felsche, 1901).
3 – Pronotum wider than elytra, brachypterous species (Figure 1 (a)). Known only from Panama (Santa Fé)................................................. D. benesi Vaz-de-Mello and Nunes, 2016. 3’ – Pronotum as wide as elytra, macropterous species................................................................ 4
4 – Surface of head densely covered with ocellate punctures larger than those on central portion of pronotum (Figure 3 (c)). Surface of elytral interstriae covered with opaque shagreened microsculpture; medial portion of interstriae with small, smooth dots appearing as pinpricks (Figure 3 (g)). Ecuador D. fortepunctatus (Luederwaldt, 1923).
4’ – Surface of head densely covered with ocellate punctures as large as those on the central portion of pronotum. Surface of elytral interstriae covered with barely shiny shagreened microsculpture; medial portion with dense shiny and smooth dots (as in Figure 3 (i))................................................................................................................................................ 5
5 – Species from Central America (Figure 6)..................................................................................... 6
5’ – Species from South America (Figure 6)........................................................................................ 9
6 – Clypeofrontal region of male with a central, apically emargined knob. Clypeofrontal region of female with a pair of knobs (Figure 3 (d)). Dorsal surface of paramera with a pre-apical longitudinal carina as long as half the paramera length (Figure 4 (i)). Panama .................................................................. D. gamboaensis Howden and Young, 1981.
6’ – Clypeofrontal region of both sexes with an acute central knob (as in Figure 2 (a,g)). Dorsal surface of paramera smooth or with strong pre-apical teeth (as in Figure 2 (d,p)).............. 7
7 – Male pronotum having a distinct anterior declivity medially (Figure 2 (m)). Dorsal surface of paramera with strong pre-apical teeth (Figure 2 (p)). Costa Rica (Puntarenas) ............................................................................................. D. rodrigoi Kohlmann and Solís, 1997.
7’ – Male pronotum having a feeble anterior declivity medially (Figure 2 (a,g)). Dorsal surface of paramera smooth (Figures 2 (d, j))............................................................................. 8
8 – Elytral striae thin and deeply punctate, punctures wider than striae. Costa Rica ............ ..................................................................................................... D. favi Kohlmann and Solís, 1997.
8’ – Elytral striae wide, crenulate, punctures almost as wide as striae. Costa Rica .................. ............................................................................................... D. danieli Kohlmann and Solís, 1997.
9 – Body elongate (Figure 1 (b)). Elytral striae thin, punctures wider than striae. Surface of elytral interstriae, in both sexes, covered with barely shiny shagreened microsculpture; medial portion with dense shiny and smooth dots (Figure 3 (i)). Ventral surface of metafemora with dense coarse punctures concentrated on apical half. Colombia ....... .......................................................................................................................... D. berthalutzae sp. nov.
9’ – Body globose (Figure 2 (s)). Elytral striae almost as wide as their punctures. Surface of elytral interstriae entirely shagreened in males; females with medial portion of elytral striae smooth. Ventral surface of metafemora densely covered with coarse punctures (Figure 2 (t)). Brazil (Amazonas) and Peru (Iquitos)....... ....... D. globulus (Felsche, 1901).
description: Published as part of Valois, Marcely C., Silva, Fernando A. B. & Vaz-de-Mello, Fernando Z., 2022, A taxonomic revision of the globulus species group of Dichotomius Hope, 1838 (Coleoptera: Scarabaeidae: Scarabaeinae), pp. 119-147 in Journal of Natural History 56 (1 - 4) on pages 122-128, DOI: 10.1080/00222933.2022.2046887, http://zenodo.org/record/6530252