Dichotomius sexdentatus (Luederwaldt)

Nunes, Rafael V. & Vaz-De-Mello, Fernando Z., 2013, New brachypterous species of Dichotomius Hope, with taxonomic notes in the subgenus Luederwaldtinia Martínez (Coleoptera: Scarabaeidae: Scarabaeinae), Zootaxa 3609 (4), pp. 411-420 : 416

Dichotomius sexdentatus (Luederwaldt) and D. simplicicornis (Luederwaldt)

Luederwaldt (1936) created the D. calcaratus species group to accommodate D. calcaratus (Arrow) , D. sexdentatus (Luederwaldt) , and D. simplicicornis (Luederwaldt) . Vulcano et al. (1976) transfered D. calcaratus to the D. buqueti species group (then in the subgenus Dichotomius ). With the transfer of the nominate species to another species group, the two remaining species, D. sexdentatus and D. simplicicornis should be placed in different species groups.

After examining the holotype (MZSP), we place D. sexdentatus in the D. crinicollis species group for the following reasons: it has a tooth on clypeal genal junction ( Fig. 2 B) and its hypomeron bears dense, long and curved, red pilosity ( Fig. 2 D). After examining the holotype of D. simplicicornis (located in the NHML) and scrutinizing the original description, we place this species in the D. agenor species group based on the cephalic horn in males constituting a transverse carina with a strong central tooth and two lateral teeth ( Fig. 2 H), which is a shared characteristic with other species in this species group.

Figures

FIGURE 2. Dichotomius eucranioides (A) black arrow indicating crenulated clypeal margin; D. sexdentatus (B) black arrow indicating tooth or protuberance on clypeogenal junction (this is also seen on D. eucranioides); D. nisus (C) black arrow indicating the asymmetry of the parameres; D. crinicollis (D) black arrows indicating pilosity on the hypomeron; D. superbus (E) white arrow indicating gibbosities on the pronotum; D. schiffleri (D. sericeus species group) (F) white arrow indicating a fovea on the posterior angle of the pronotum; D. speciosus (G) black arrows indicating cephalic transversal carina; D. agenor (H) black arrow indicating male cephalic carina; D. glaucus (D. carbornarius species group) (I) elytra microsculpture.