A new species of the genus Canthon Hoffmannsegg (Coleoptera, Scarabaeidae, Scarabaeinae, Deltochilini) from central Brazil

A new species of Canthon is described, illustrated and the morphological similarities with related species are discussed. The species Canthon cleidecostae was named after Dr. Cleide Costa a great beetles specialist. The subgeneric category of species is considered incertae sedis until the taxonomic revision of the genus Canthon is fully addressed. Also, we provide a key for genera, subgenera and isolated species-groups that can be confused with the genus Canthon.

Here, we present a new species to science belonging to the genus Canthon. Considering the plasticity of characters of this group and the clear artificiality of many of its internal divisions, we decided not to include Canthon cleidecostae sp. nov. in any subgeneric position. Thus, to avoid the taxonomic complication we will keep Canthon cleidecostae sp. nov. as incertae sedis.

MATERIAL AND METHODS
For type material, labels are transcribed in verbatim in quotation marks ("…"). The single slash (/) is used to a new line on a same label. Label colour or other additional information is given in brackets ([…]). Type specimens are deposited at Seção de Entomologia da Coleção Zoológica da Universidade Federal do Mato Grosso, Cuiabá, Brazil (CEMT). Morphological analysis and comparisons were conducted using a Leica stereomicroscope model S8AP0. All photographs were made using a stereomicroscope Leica model m205C (7.8X-160.0X) with image capture system MC190 HD.
The methods of extraction and preservation of internal sac follow Zunino (1978). The external morphology was based on Edmonds (1972) and Tarasov & Génier (2015). For the microsculpture description we follow the terminology proposed by Harris (1979). All length measurements mentioned in the description are in millimetres (mm).
Protibiae Metafemora  (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.

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 (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).