Dichotomius (Cephagonus) seag, 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 : 2301-2302

2.6.: Dichotomius (Cephagonus) seag new species

( Figure 25 )

Diagnosis. distinguished from the other species in the group by the following combination of characteristics: males ’ cephalic carina longer than wideı with a rounded apex (as in medium males of D. bicuspis of bicuspis group); anterior and posterior pronotum portions with very fine punctuation (viewed under 30x magnification); males ’ pronotal disc with a single-rounded lobe at the anterior portion (as in D. fissus of the same group); pronotal margin smooth and; elytral striae with indistinct punctuation.

● HOLOTYPEı male: GUYANNE FRANÇAISE: Cayenne: Nouragues Biological Reserve. Fezes Allouatta . iii-1997. F Feer [at CEMT ].

● PARATYPES: same data of Holotype [1Ƌ]; SURINAME: Sipawilini. Palumeu River. 2³28 ’ Sı 55 ³37 ʹ W. iii-2012. T Larsen [2 ƋƋ at CEMT].

Description. (maleı holotype): BL: 23 mmı PW: 13 mm. Colour: blackı with brown elytra. Head: fronto-clypealı genal and inter-ocular surfaces smooth. Gena borders slightly curved inwards. Cephalic carina longer than wideı rounded at the apex. Pronotum: borders smoothı not serrated. Pronotal disc shinyı lacking punctuation and delimited anteriorly by a singleı rounded lobe. Anterior portionı including excavation and anterior angles with very fineı equally spaced punctures (viewed under 20x magnification). Posterior margin with two rows of small ocellate punctures. Metasternum: sides and anterior portion of anterior lobe covered by dense red setae. Setigerous punctuation equally spacedı where present. Elytra: striae weakly impressed lacking distinct punctuation. Striae expanding near the base forming foveae. Interstriae brown colourı lacking microsculpture. Abdomen: glabrousı punctuation of ventrites anterior margininterrupted medially. Aedeagus ( Figure 21 (c-e)): parameraı apexes rounded dorsallyı convergent; longitudinal excavation taking 3/4 of paramera length; basal excavations rounded. Laterallyı subtle declivity towards apex; posterior margin with an emargination near junction with phalobasis. Ventrallyı sclerotised portion excavatedı forming a groove constrained at mid-portion; subgenital plate rounded at basis and emarginated at apex.

Morphological variation. male BL: 17 – 23 mmı PW: 9 – 13 mm. Female BL: 17 mmı`PW: 9 mm and is distinguished from males as follows: Head: fronto-clypeal surface with coarse puncture. Cephalic carina transversalı forming a weak pair of tubercles. Pronotum: simply convexı lacking lobes. Elytra: striae deeply impressedı punctures separated by twice their diameter. Abdomen: sixth ventrite bearing a pair of triangular projections reaching pygidium apical margin ( Figure 9 (b)).

Distribution. French Guyanaı Suriname ( Figure 20 ).

Etymology. named after the Société Entomologique Antilles Guyane (SEAG)ı responsible for the holotype collection.

Figures

Figure 9. (a) Abdominal ventrites of a male of D. spadiceus. (b) ventrites of a female of D. spadiceus. (c) abdominal ventrites of a female of D. itatiaiaensisı (d) detail of C; (e) abdominal ventrites of a female of D. fissus. (f) Adbominal ventrites of a female of D. reichei. (g) Abdominal ventrites of a female of D. lucianomourai.

Figure 20. Distribution map of the species in the D. fissus group.

Figure 21. D. fonsecae: (a) male dorsal habitus; (b) Holotype dorsal habitus; (c) holotype labels; (d) female dorsal view; (e) female ventral view; (f) paramera dorsal view; (g) paramera ventral view; (h) paramera lateral view.

Figure 25. D. seag: (a) male dorsal habitus (Holotype); (b) male ventral habitus; (c) paramera dorsal view; (d) paramera ventral view; (f) paramera lateral view.