Dichotomius (Cephagonus) ricardosilvai, Nunes & Vaz-de-Mello, 2019

Nunes, Rafael V. & Vaz-de-Mello, Fernando Z., 2019, Taxonomic revision of Dichotomius (Cephagonus) Luederwaldt 1929 and the taxonomic status of remaining Dichotomius Hope 1838 subgenera (Coleoptera: Scarabaeidae: Scarabaeinae: Dichotomiini), Journal of Natural History 53 (37), pp. 2231-2351 : 2326-2327

3.20.: Dichotomius (Cephagonus) ricardosilvai new species

( Figure 40 (a-e))

Diagnosis. separated from other species in the quadraticeps group by the following combined characters: larger males cephalic carina bifurcated at apex (as D. fonsecae and D. rondoniaensis ); larger males pronotum with a rounded central lobe (as D. barbarae ); posterior margin of pronotum having 1 – 2 rows of ocellate puncture; groups of ocellate puncture beneath each mid-lateral pronotal pit; paramera (lateral view) with abrupt declivity produced by basal knobs; paramera (lateral view) posterior margin with very small emargination close to phalobasis junction.

● HOLOTYPE (male): BRASIL: Mato Grosso. Cotriguaçú. Fazenda São Nicolau. 9³49 ʹ 09 ” Sı 58³15 ʹ 47 ” W. Fezes humanas. 8-10-xii-2008. FZ Vaz-de-Mello [at CEMT].

● PARATYPES: same data of holotype but: 9³50 ʹ 19 ” Sı 58 ³15 ʹ 03 ” W. x-2009 [1 Ƌ at CEMT]; same data but ii-2008. O Peres-Filho [1 ♀ at CEMT]; BRASIL. Mato Grosso. Comodoro. Morro Sem Boné. 13³43 ʹ 54 ” Sı 60 ³18 ʹ 40 ” W. x-2012. MF Souza [1 Ƌ at CEMT]; Tangará da Serra. Fazenda Curitiba. 14³22 ʹ 18 ” Sı 57³29 ʹ 24 ” Wı 343 m. Floresta semidecídua. Fezes humanas. 31-iii-2012. RJ Silva [1 Ƌ at CEMT].

Description (Holotypeı male). BL: 20 mmı PW: 13 mm. Colour: blackı shiny. Head: dorsal surface smooth. clypeo-genal junction with very small emargination (which produces clypeo-genal groove). Clypeo-genal angle obtuse 100³. Cephalic carina longer than wideı strongly bifurcated at apex producing a tubercle on each end. Pronotum: borders smoothı not serrated. Pronotal anterior portion with fine punctures getting coarser towards anterior margin. Group of ocellate punctures present beneath mid-lateral pit. Posterior margin with 1 – 2 rows of ocellate punctures. Pronotal disc smoothı shinyı anterior portion having a wide central-rounded lobe. Metasternum: sidesı margins of anterior lobe and anterior portion of anterior lobe covered by setigerous ocellate punctures. Setigerous punctures equally spaced at sides. Elytra: striae deeply impressed having fine punctures spaced by twice their diameter. Interstriae convexı disc with dark brown colourı lacking microsculpture with very fine puncture (20x). Abdomen: sides of each ventrite covered by ocellate punctures with very short setae (35x) and excavated near anterior margin. ventrite 1 having groups of 8 – 10 longer setae on each side. Puncture of each ventrite interrupted medially as well as groove along the posterior margin of sixth ventrite. Aedeagus: as in ( Figure 40 (c-e)): dorsallyı paramere apexes roundedı convergent; longitudinal excavation present taking 2/3 of paramera length; basal-rounded excavation present. Laterallyı abrupt declivity from basis towards apexı produced by basal knobs; posterior margin with small emargination close to phalobasis junction. Ventrallyı each paramera with a lateral-rounded excavation; subgenital plate widely emarginated basally and rounded apically.

Morphological variation. males BL: 17 – 20 mmı PW: 10 – 13 mm. Larger males have developed cephalic carina (bifurcated at apex) and pronotal lobe. The unique smaller male we have noticed do not have pronotal lobes while the cephalic horn is produced in a low-bifurcated carina. Both males phenotypes and females have similar puncture and hair distribution pattern. Females BL: 16 mmı PW: 9 mmı distinguished from males as follows: Head: fronto-clypeal surface striated. Coarse puncture present posterior to cephalic carina on interocular space. Cephalic carina absent produced in a pair of weak knobs. Pronotum: simply convexı lacking lobes. Posterior margin with strong ocellate punctures. Coarse puncture beneath mid-lateral foveae. Abdomen: sixth ventrite three times larger than fifth.

Distribution. Brazilı state of Mato Grossoı north to Paresi formation ( Figure 36 ).

Etymology. named after our friend and entomologist Dr. Ricardo José da Silva (Universidade do Estado de Mato Grossoı Brasil)ı who collected the type series.

Figures

Figure 36. Distribution map of D. ricardosilvaiı D. marcoscarvalhoiı D. furtadoiı D. barbaraeı D. tissianiaeı D. eması D. frizzasae and D. candangoi.

Figure 40. D. tissianiae: (a) larger male dorsal habitus; (b) smaller male dorsal habitus; (c) paramera dorsal view; (d) paramera ventral view; (e) paramera lateral view. D. ricardosilvai: (f) larger male dorsal habitus; (g) smaller male dorsal habitus; (h) paramera dorsal view; (i) paramera ventral view; (j) paramera lateral view.