Dichotomius (Cephagonus) rondoniaensis, 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 : 2335-2336

6.1.: Dichotomius (Cephagonus) rondoniaensis new species

( Figure 47 (a-d))

Diagnosis. separated from other species in the quadraticeps group by the following combined characters: larger male cephalic carina bifurcated at apex (as D. fonsecae and D. ricardosilvai ); larger male pronotum with a central pair of rounded lobe on the anterior portion of the disc (as D. reichei ); female sixth ventrite having a central excavation with a central pair of knobs ( Figure 10 (d)).

● HOLOTYPE (male): BRASIL: Rondônia. Porto Velho. ESEC-Cuniã 8³4 ʹ 11 ” Sı 63³28 ʹ 64 ” W. 5-7-XII-2011. Pitfall Banana . MAPA Silveira [at CEMT ].

● PARATYPES: same data of Holotype [4 ƋƋı 4 ♀♀ at CEMT]; BRASIL. Pará. [1 ♀ at CEMT]; Maranhão. [1 ♀ at CEMT]. PERU. Madre de Dios [1 Ƌı 1 ♀ at CEMT].

Description (Holotypeı male). BL: 22 mmı PW: 12 mm. Colour: blackı shiny. Head: dorsal surface smooth. Clypeo-genal angle obtuse (100³). Cephalic carina longer than wideı bifurcated at apex producing a tubercle on each end. Pronotum: anterior portion with fine punctures evenly spaced; group of ocellate punctures present beneath mid-lateral foveae; posterior margin with 1 – 2 rows of ocellate punctures. Disc smoothı shinyı anterior portion with four tubercles aligned transversely. Metasternum: sides and margins of anterior lobe covered by setigerous ocellate punctures. Middle portion of anterior lobe glabrous and lacking punctures. Setigerous punctures equally spaced at sides. Elytra: striae deeply impressed having fine punctures spaced by 1-three times their diameter. Interstriae convexı disc with dark brown colourı lacking microsculpture with very fine punctures (20 x). Abdomen: sides of each ventrite covered by ocellate punctures with very short setae (35x) and excavated near anterior margin. Ventrite 1 having 1 – 2 longer setae on each side. Puncture of each ventrite interrupted medially as well as groove along the posterior margin of sixth ventrite. Aedeagus ( Figure 47 (b-d)): dorsallyı paramere apexes roundedı convergent; longitudinal excavation present taking whole paramera length; basal-rounded excavation present. Laterallyı abrupt declivity from basis towards apex. Ventrallyı each paramera with a lateral-rounded excavation; subgenital plate widely emarginated basallyı rounded at apex.

Morphological variation. male BL: 19 to 22 mmı PW: 11 – 12 mm. Female BL: 18 – 22 mmı PW: 11 – 13 mmı distinguished from males as follows: Head: fronto-clypeal surface striated. Middle portion of interocular surface with chagrinated microsculptureı coarse puncture present near eyes. Cephalic carina not bifurcated apically. Pronotum: simply convexı lacking lobes. Posterior margin with strong ocellate punctures. Coarse puncture beneath mid-lateral pit. Abdomen: female sixth ventrite having a single shape in selenocopris: composed by a pair of central tubercles that do not advance beneath pygidium apexı lateral to each tubercleı a triangular projection of the posterior margin advances beneath pygidium apex ( Figure 10 (d)).

Distribution. Brazil (PAı MAı RO)ı Peru (Madre de Dios).

Systematic remarks. males of this species are similar to those of quadraticeps group; howeverı females have a different 6th abdominal sternite among Cephagonus and Dichotomius ( Figure 10 (d)). This species has a wide distribution however two localitiesı in Maranhão and Paráı are represented by very similar females. We do not know what to expectı but despite the very localised endemisms found in Cephagonus ı some species like D. asenjoi have also have a wide and similar distribution.

Etymology. specific name refers to the state of Rondôniaı Brasil while the state was named after Marshall Cândido Rondon (1865 – 1958).

Figures

Figure 10. (a) Abdominal ventrites of a male of D. vargasae. (b) Detail of a sixth ventrite (white arrow) of a female of D. vargasae. (c) Sixth ventrite of female of D. vargasae. (d) Abdominal ventrites of a female of D. rondoniaensis. Pyg – pygidium.

Figure 47. D. rondoniaensis: (a) male dorsal habitus; (b) paramera dorsal view; (c) paramera ventral view; (d) paramera lateral view. D. vargasae: (e) male dorsal habitus; (f) paramera dorsal view; (g) paramera ventral view; (h) paramera lateral view.