Canthon cleidecostae, Vaz-de-Mello & Nunes & Costa-Silva, 2020

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 : 3-5

Canthon cleidecostae sp. nov. ( Figs. 1-3 )

Type material: HOLOTYPE (♂ CEMT): First label [white, typeset]: “ BRAZIL: Goiás, Monte / Alegre de Goiás, / 13°14′10″S, 47°09′19″W, / 13.iii.2013, Kerodon / acrobata feces, Alexandre / leg.”. Second label [red, handwritten]: “ Canthon cleidecostae / Vaz-de-Mello, Nunes / & Costa- Silva / HOLOTYPE ” . PARATYPE (1♂ CEMT): First label [white, typeset]:“ BRAZIL: Goiás, Monte / Alegre de Goiás, / 13°14′10″S, 47°09′19″W, / 13.iii.2013, Kerodon / acrobata feces, Alexandre / leg.”. Second label [yellow, handwritten]: “ Canthon cleidecostae / Vaz-de-Mello, Nunes / & Costa-Silva / PARATYPE ”.

Diagnosis: Canthon cleidecostae sp. nov. is most similar to Canthon ibarragrassoi , with which it shares the metafemora with a sinuous carina close to the anterior margin ( Fig. 3 ). Furthermore, it can be easily separated by the clypeal teeth, which are U-shaped in C. cleidecostae sp. nov. and V-shaped in C. ibarragrassoi . The colour is also characteristic while C. cleidecostae sp. nov. is metallic green and C. ibarragrassoi present black colouration.

Description (Holotype, Male): Dorsal habitus ( Fig. 1A ). Body length (except the head) 7.55 mm. Head: dorsal surface slightly concave with green alveolar microsculpture; posterior half with finely spaced punctation and anteri- or half with superficial rugosities. Two triangular clypeal teeth, with rounded apex, separated by a U-shaped emargination ( Fig. 1D ). Clypeal margin and lateral margin of head with yellow setae emanating from underneath. Clypeo-genal suture present and oblique until close to eyes. Pronotum: pronotal disc smooth, metallic green, bright with green alveolar microsculpture. Anterior angles acute, pointed forward ( Fig. 1C ). Lateral margin smooth with two little teeth and brief emargination between them (more visible in lateral view). Hypomeron: dark green, with coriarious microsculpture, sparse yellowish setae anteriorly, and thin transverse carina at centre not touching lateral margin; anterior region slightly concave ( Fig. 1B ). Elytra: surface with dark green colour, less bright than pronotum; with fine micropuncture. Striae narrow and poorly visible, with punctation; interstriae wide, flat. Legs: protibiae with three main teeth on outer edge and crenulated until the base; protibial spur flattened dorsoventrally, bifid, asymmetrical ( Fig. 2A ). Mesofemora with ventral side lacking anterior and posterior margin. Metafemora subclaviform, with a sinuous carina ( Fig. 3A , white setae); yellow setae on the anterior edge and close to apex; posterior edge with lobe comprising two-thirds apically ( Fig. 3A ). Abdomen: surface with alveolar microsculpture; dark green. Ventrites with tufts of small yellow setae on each side laterally and medially glabrous ( Fig. 1B ). Pygidium: as wide as long; bright green without punctation. Basal margin expanded, forming strongV-shaped carina between pygidium and propygidium. Parameres: lateral view: symmetrical; apex truncate ( Fig. 2B ). Superior edge straight and inferior concave, never sinuous. Apical-laterally edge with bulge at centre. Dorsal view: membranous portion separating parameres from base to apex. Internal sac: peripheral fronto-lateral sclerite (FLP) connected to of the axial sclerite (Ax), both sclerites forming an apical complex, in which Ax forms a central semiduct ( Fig. 2E , Ax [black arrow]) and FLP completes the circunference in the semiduct (Ax) (like a roof), base and apex of all the complexes of equal size, without tapered region; subaxial sclerite (SA), about the same size as other sclerites, covering ventrally the FLP + Ax complex; peripheral medial sclerite (MP) flat, rolled, with the basal part more acute (in relation to the apex), lateral in relation to FLP + Ax; superior right peripheral sclerite (SRP) with lateral angular prolongation ( Figs. 2 E-F).

Morphological variation: The variation between the two specimens of the type series is centred on the body length, which varied from 6.05 mm (paratype) to 7.55 mm (holotype).

Etymology: This species is named after Dr. Cleide Costa, in acknowledgement of her great contribution to the study of Coleoptera and for supervising many Brazilian coleopterists. An important remark is that the larva of this species is still unknown and we hope it will be described in collaboration with Dr. Costa when available.

Distribution: So far, this species is only known from the type locality (Monte Alegre de Goiás, Goiás state) ( Fig. 4 ).

Biology: Nothing is known about the biology of C. cleidecostae sp. nov. The feeding habits are probably coprophagous, considering related species of the same genus. Besides, the type-series was collected in Kerodon acrobata Moojen, Locks & Langguth, 1997 faeces, a rodent endemic of Brazil and know only to Goiás state ( Woods & Kilpatrick, 2005).

Comments: The placement of this new species within the subgenera of Canthon is still uncertain. Some morphological characteristics used to describe this species are similar to Canthon ibarragrassoi ( Martínez, 1952) , mainly considering the sinuous carina in the metafemur.

The geographic distribution of both species is distinct. Canthon cleidecostae sp. nov. is known for the type locality as aforementioned, while Canthon ibarragrassoi is recorded to Paraguay (type locality: Colonia Natalício Talavera), Argentina ( Mesopotamia Argentina) and Brazil (Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Mato Grosso do Sul, Rio de Janeiro, Minas Gerais and Espirito Santo states, the latter state being the northernmost known record of the species.

As currently understood, C. ibarragrassoi belongs to the subgenus Glaphyrocanthon considering many characteristics listed by Halffter & Martínez (1977: 79). However, even C. cleidecostae sp. nov. sharing these characteristics with C. ibarragrassoi we concluded that the new species should not be included in the Glaphyrocanthon without a detailed taxonomic revision of this subgenus. Thus, to avoid “taxonomic instability”, we regard Canthon cleidecostae sp. nov. as incertae sedis.

In addition, the sclerites of the internal sac are not similar to those found in Goniocanthon Pereira & Martínez, 1956 ( Nunes et al., 2018), nor in Peltecanthon (Nunes et al., in press), where the Ax + FLP complex gradually tapers to a much thinner apex, or even other Canthon handled by one of the authors (Nunes, personal remarks). In Canthon cleidecostae sp. nov., the apex is not thin, something similar to that observed in Tetraechma Blanchard, 1845 (Nunes, personal remarks).

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 2. Details of structure in Canthon cleidecostae sp. nov.: (A) male protibial apex, dorsal; Male genitalia: (B) aedeagus, lateral; internal sac: (C) dorsal and (D) ventral views;internal sac apical and parietal sclerites:(E) dorsal and (F) ventral views [Ax= axial sclerite;FLP = fronto-lateral peripheric sclerite;MP = medial peripheric sclerite;SA = subaxial sclerite;SRP = superior peripheric sclerite].Black arrow showing the semiduct.Scale bars:A-D = 1 mm; E and F = 0.5 mm.

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

Figure 4. The distribution record of Canthon cleidecostae sp. nov., central Brazil [TO = Tocantins;MT = Mato Grosso;GO = Goiás;DF = Distrito Federal; BA = Bahia;MG = Minas Gerais;MS = Mato Grosso do Sul].