Dichotomius eucranioides Pereira & D’Andretta, 1955

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 : 415

Notes on Dichotomius eucranioides Pereira & D’Andretta

Since the time of its description ( Pereira & D’Andretta 1955), D. eucranioides has maintained a doubtful position within the subgenus Luederwaldtinia . Pereira & D’Andretta (1955) did not assign this species to a species group but Vulcano et al. (1967) later placed it in the D. assifer species group due the presence of a transversal carina on the head of males. However, we believe that D. eucranioides should be considered to be in its own species group within the subgenus for the following reasons: it is the only species in the genus that has a crenulate clypeal margin ( Fig. 2 A); the transversal carina width on the head is subequal to the distance between the eyes and is greater than its height; the pronotal disc of males is anteriorly delimited by four gibbosities; the pronotal declivity of males has two lateral depressions filled with ocellate punctures; and, contrary to the species of D. assifer species group, D. eucranioides hypomeron do not have an anterior excavation delimited medially by a dense brush of red setae. Although D. eucranioides is a brachypterous species, we decided not to redescribe herein since the descriptions of the female (holotype, Pereira & D’Andretta 1955) and of the male ( Vulcano et al. 1976) are detailed enough.

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.