Canthon

Vaz-de-Mello, Fernando Z., Nunes, Luis Gabriel de Oliveira Albuquerque & Costa-Silva, Vinícius da, 2020, A new species of the genus Canthon Hoffmannsegg (Coleoptera, Scarabaeidae, Scarabaeinae, Deltochilini) from central Brazil, Papéis Avulsos de Zoologia 60 (4), pp. 1-6 : 2

Key to genera, subgenera and isolated species-groups easily confused with Canthon

occurring in South America (beginning from couplet 90 in Vaz-de-Mello et al., 2011)

1. Basal meso- and metatarsomeres short,length about one-half that of the second tarsomere,obliquely (nearly 45°) truncated apically( Vaz-de-Mello et al., 2011,fig.155).Lateral borders of meso- and metatarsomeres parallel,forming a continuous border for all tarsi,overall shape of tarsomeres 2-4quadrate to rectangular.Dorsal surface of mesotibiae with dense setae,not in line.Pygidium never separated from propygidium by transverse carina.Widespread in tropical forest areas................................................................................................................. Scybalocanthon Martínez,1948 (see Silva & Valois,2019)

1 ′ Length of basal meso- and metatarsomeres only slightly less than,or greater than,that of tarsomere 2; if much smaller,then nearly transversely truncated apically.Lateral borders of meso- and metatarsomeres separately divergently apically,the overall shape of tarsomeres 1-4 trapezoidal;dorsal surface of mesotibiae with setae arranged in line.............................................................................................................................................................................. 2

2(1 ′). Pygidial base covered by elytra; tips of elytra overhang base of pygidium (which is not separated from propygidium), not appressed to base. Pubescent dorsum with yellow to red spots on elytra.Sides of pronotum serrate. Bolivia,and maybe Brazil and Venezuela................................................................ .............................................................................................................................. Canthonidia Paulian,1938 (revision is needed,probably monospecific)

2 ′. Pygidial base completely exposed (but propygidium not exposed); tips of elytra not overhanging base of pygidium,appressed to pygidial base.Glabrous dorsum;if pubescent,then monocoloured.Sides of pronotum not serrate........................................................................................................................3

3(2 ′). Dorsum (especially prothorax) with irregular sculpturing (mosaic of smooth, sericeous and microgranular areas, irregular ill-defined elevations and depressions) or with well-defined prothoracic tubercles ................................................................................................................................................... 4

3 ′. Pronotum with evenly distributed sculpturing, at most with posteromedian depression, never with tubercles. Widespread, except Chile Canthon Hoffmannsegg,1817 (if transverse teeth or carinae are present in the lateral face of mesotibia,then check Vaz-de-Mello et al., 2011, couplet 89).........5

4(3). Protibiae truncated in straight angle at apex.Male with elongatedY-form expansion derived from clypeal teeth,female with clypeal teeth widely separated. Southernmost of Brazil (Rio Grande do Sul) and Argentina (Buenos Aires)......... Xenocanthon Martínez,1952 (monospecific, X.sericans ( Schmidt,1922))

4 ′. Protibiae obtusely truncated at the apex.Both male and female with similar clypeus,with teeth separated byV emargination.Chacoan depression,Cerrado, Orinoquía and Amazonia .............................................................................................................. Anisocanthon Martínez & Pereira,1956 (under revision)

5(3 ′). Ventral surface of metafemora with longitudinal sinuous carina,nearer anterior edge at base and more distant towards apex........................................... 6

5 ′. Ventral surface of metafemora with either anterior margin (carina) straight and very close to anterior edge all over (sometimes vanishing apically) or with no anterior margin or carina..............................................................................................................................................................................................7

6(5). Green body.Longitudinal sinuous carina of metafemora nearly paralleling anterior border in the apical half ( Fig.3A ).Metafemur postero-apically lobed at least in males.Pygidium very convex........................................................................................................... Canthon (s.l.) cleidecostae sp.nov. ( Figs.1 A-D)

6 ′. Body black.Longitudinal sinuous carina of metafemora basally and apically very close to anterior border,but never parallel to it ( Fig. 3B ). Metafemur not postero-apically lobed.Pygidium feebly convex.................................................................................................................................................................. ............................................................. Canthon (Glaphyrocanthon) (pars,species around C.ibarragrassoi ( Martínez,1952) and species still undescribed)

7(5 ′). Ventral surface of metafemora not margined anteriorly........................................................................................................................................................ 8

7 ′. Ventral surface of metafemora with fine margination anteriorly (sometimes vanishing apically)....................................................................................... 11

8(7). Pygidium strongly convex,very shiny.Amazon and Atlantic Forest...................... Canthon (Goniocanthon) Pereira& Martínez,1956 (see Nunes et al., 2018)

8 ′. Pygidium flat or slightly convex,dull or slightly shiny...........................................................................................................................................................9

9(8 ′). Metafemora elongate,claviform.Atlantic Forest.................................................................. Canthon (Peltecanthon) Pereira,1953 (see Nunes et al., in press)

9 ′. Metafemora not claviform................................................................................................................................................................................................... 10

10(9 ′). Dorsum with distinct and dense uniform pubescence,dorsum completely opaque.Body flattened.Protibial teeth closely set near the apex of tibia.Northern Amazonia................................................................................ Canthon (Trichocanthon) Pereira& Martínez,1959 (monospecific, C.sordidus Harold,1868 )

10 ′. Dorsum either glabrous or with minute sparse pubescence.Protibial teeth widely spaced along apical half of lateral margin.Widespread,except Chile...... ....................................................................................................................................... Canthon (Glaphyrocanthon) Martínez,1948 (probably to be split)

11. Pygidium and propygidium not separated by transverse carina.South and Central America............... Canthon Hoffmansegg,1817 : septemmaculatus group

11 ′. Pygidium and propygidium at least partially separated by transverse carina...................................................................................................................... 12

12. Head anteriorly either sinuous or slightly emarginated,sometimes without clypeal teeth.Pronotum with prescutellar depression; adjacent area of elytra with scutellar depression.Open areas in Chaco,Pampa,Cerrado and Caatinga................. Canthon (Pseudepilissus) Martínez,1954 (see Vieira et al., 2019)

12 ′. Clypeus with at least two (sometimes more) well-defined clypeal teeth.Central teeth separated from each other by narrow emargination.Body usually not depressed around scutellum............................................................................................................................................................................................13

13. Anterior margin of profemora either with one large tooth close to concavity or with several well-defined denticles (inside concavity or not). Brazil, Argentina, Bolivia, Paraguay, Uruguay;not present in Amazonia ......................................................... Canthon (Francmonrosia) Pereira & Martínez,1959

13 ′. Profemora lacking anterior denticles or teeth.Widespread in South America................................................. Canthon s.str. Hoffmansegg,1817 (to be split).

Figures

Figure 1. Holotype of Canthon cleidecostae sp.nov.:(A) dorsal;(B) ventral;and (C) lateral view;(D) head,dorsal view.Scale bar:1 mm.

Figure 3. Metafemur, ventral view of (A) Canthon cleidecostae; and (B) Canthon ibarragrassoi.Scale bar:1 mm.