Isacanthon mariaelinae Pacheco, 2019

Pacheco, T. L. & Vaz-de-Mello, F. Z., 2019, New dung beetle genus and species from a cave in the Espinhaço mountain rangeı Brazil (Coleoptera: Scarabaeidae: Scarabaeinae), Journal of Natural History 53 (19), pp. 1247-1253 : 1249-1251

Isacanthon mariaelinae Pacheco and Vaz-de-Mello gen. et sp. nov.

( Figure 1 (a – d))

Holotype

Male, here designated, ‘ Brasil: Minas Gerais, Diamantina, Gruta do Manéu,18°16 ʹ 53 ’ S, 43° 30 ʹ 57 ” W, 20.ii.2014, folhiço, R.Fonseca-Ferreira & B. Monte cols. ” (CEMT).

Type locality

Gruta do Manéu, Diamantina, Minas Gerais State, Brazil.

Description

Body: flattened; entire surface covered with microsculpture; entire surface, except anterior part of hypomeron, and tibiae and mesocoxae, with rounded ocellate punctures with setae. Colour: dark brown. Head: entire margin bordered. Clypeus with two teeth appearing to originate beneath clypeal margin. Short tooth on emargination of the clypeo-genal carina. Fronto-clypeal carina absent. Pronotum: surface with wider punctation near the external edge, narrower punctures at the centre. Hypomeron: transversal carina present separating hypomeron into two parts; anteriorly with strong excavation, surface with microsculpture; posterior surface with sparse ocellate punctures. Prosternum: short, without longitudinal carina. Mesepimeron, mesoventrite, metepisternum and metaventrite: short mesepimeron without bordered margins. Carina almost straight between mesoventrite and metaventrite Legs: Prolegs with an anterior trochantofemoral pit. Mesofemora elongated; metafemora with angulation of 90° on posterior margin. Protibiae with three distinct teeth and fully interrupted externally by fine teeth (including between the three larger teeth); mesotibiae without lateral teeth; metatibiae with distinct tooth at its basal two-fifth; all tibial spurs elongated, length of protibial spur almost equal to the fourth protarsomere, length of meso- and metatibial spur almost equal to the first meso- and metatarsomere. Five tarsomeres in all legs, fifth protarsomere almost equal to the other four combined, length of the first meso- and metatarsomeres almost equal to meso- and metatarsomeres two and three; second to fifth becoming smaller towards apex; two curved tarsal claws in all legs. Elytra: With eight striae. First interstria with one row of rounded ocellate punctures with seta. Second interstria with ocellate punctures with setae, no rows defined in the first half, the second half with two rows well-defined. Interstriae three to seven with two rows of ocellate punctures with setae and some additional spots (ocellate) between rows. Pseudoepipleuron: very large, with one stria. Ventrites: first to fifth with one row of elongated punctures near to the anterior edge, in lateral edges with rounded punctures without forming any rows. Sixth ventrite completely covered by rounded punctures. Pygidium: vertical, surface completely covered by rounded punctures. Aedeagus: phallobase and parameres of equivalent length. Parameres asymmetric; the external face of right paramere with a tapered apex and strong concave angulation at the basal part of anterior margin; external face of left paramere with squared apex, slightly concave angulation in anterior margin and posterior margin with angulation of 90° at medial part.

Etymology

Named after Prof. Dr. Maria Elina Bichuette (Laboratório de Estudos Subterrâneos da Universidade Federal de São Carlos – UFSCar), a Brazilian biologist, leader of the cave zoology project under which the specimen was collected. In recognition of her wish that specialists study the specimens she collected.

Discussion

Based on the morphological characters, there is no question that Isacanthon gen. nov. and Paracanthon are closely related, in view of their similarities in body shape, microsculpture and punctuation, colour, elytral striae, pseudoepipleuron and parameres. At the same time, the relationships between these genera and other Scarabaeinae are not obvious. Vaz-de-Mello (2007) suggested that Paracanthon is closely related to Paracryptocanthon , Cryptocanthon , Tesserodoniella and other genera placed by him in a revalidated tribe Demarziellini. However, Tarasov and Génier (2015), in a phylogenetic study of the Scarabaeinae based on morphological evidence, did not corroborate the monophyly of that tribe as delimitated by Vaz-de-Mello (2007). Tarasov and Dimitrov (2016), based on molecular data, suggested that Paracanthon is close to Cryptocanthon , Tesserodoniella and other genera traditionally placed in other tribes. Additionally, it is worth noting that the taxonomy of Cryptocanthon , Paracryptocanthon, Paracanthon and Tesserodoniella have already been revised ( Cook 2002; Pacheco and Vaz-de-Mello 2017, Forthcoming 2019; Vaz-de-Mello and Halffter 2006), which eliminates the possibility that the new species described herein has already been described and is misclassified in some of those genera. Despite this, a comprehensive analysis is necessary to understand the phylogenetic placement of these genera.

Additionally, there are few records of Scarabaeinae collected from caves, whether they are true troglobites or specimens accidentally collected from these settings (most available records are in the second category) ( Slay et al. 2012). The most common literature records mention species of Onthophagus Latreille, 1802 in North America (e. g. Zunino and Halffter 1988, 2007). In South America, the only species (and type series) recorded from caves belongs to Deltochilum bordoni Halffter and Martínez, 1976 . After the species was described, more specimens were collected from localities that are far away from and outside of caves, suggesting that the collection of the type material from a cave was an accident (FZV pers. obs.). It is possible that the same is the case for Isacanthon mariaelinae sp. nov. Although the only specimen captured is from a cave, it does not present troglophilic characteristics, thus showing that only future collections can elucidate the real habits of this species.

Figures

Figure 1. Isacanthon mariaelinae sp. nov. (a) Lateral view. (b) Dorsal view. (c) Right view of the aedeagus. (d) Left view of the aedeagus. Scar bars: (a,b) 500 mm; (c,d) 500 μm.