Ateuchus alutacius Kohlmann & Solís, 2012

Kohlmann, Bert & Solís, Ángel, 2012, New species and revalidations of scarab beetles (Coleoptera: Geotrupidae: Athyreini and Coleoptera: Scarabaeidae: Scarabaeinae) from Costa Rica and Panama, Zootaxa 3193, pp. 28-52 : 32-35

Ateuchus alutacius Kohlmann & Solís , new species

Figs. 4 , 5 , 14

Diagnosis. This species is distinguished from other Costa Rican species by the following combination of characters: body slightly globose; head disc finely punctured with coarse punctures along clypeal margin; eyes viewed from above three times longer than wide; pronotum finely punctured with some coarse punctures at the base of the mid-line and anterior angles; surface of head and pronotum smooth; anterior pronotal margin incomplete; proepisternum shagreened and finely punctured; elytra, pygidium, and abdominal sternites strongly shagreened; profemur with a smooth surface; brachypterous.

Description. Holotype. Female ( Fig. 4 ): Length 7.1 mm. Humeral width 4.0 mm. Body oblong and slightly globose. Head and pronotum black with cupreous red reflections, elytra black, shagreened, with faint cupreous red reflections; venter dark brown, legs less so, abdominal sternites black with faint cupreous red reflections.

Clypeal margin coarsely punctate, with a broad band of strong cupreous red reflections and broadly V-shaped; tooth on each side rounded; lateral margin arcuate; dorsal surface of head finely punctate, with faint cupreous red reflections; frons and vertex tumid; eyes appear small from above (three times longer than wide).

Disc of pronotum finely punctate with some coarse punctures at the base of mid-line and anterior angles; midline only impressed one-third the pronotal length; anterior pronotal margin incomplete. Proepisternum shagreened and finely punctured; proepimeron finely wrinkled.

Elytral surface strongly shagreened, with faint red cupreous reflections; striae slightly impressed and feebly punctate, more strongly impressed at the apex of the four inner striae; intervals slightly convex. Brachypterous, wing about half the size of an A. candezei wing ( Fig. 5 ). Pygidium wider than long, very convex, and strongly shagreened with small reflective spots, completely grooved.

Protibia quadridentate, basal tooth small, protibial spur long and slender; profemora, mesofemora, and metafemora short, thick and with their ventral surface smooth. Abdominal sternites black, strongly shagreened; last one broad and with small reflective spots, the others with a line of coarse punctures at their base and a second incomplete line of coarse punctures near their centre.

Examined material (1 specimen). Holotype, female: COSTA RICA. Prov. Puntarenas. Golfito. Camino a Cerro Paraguas. Finca de Pito. 1100–1200 m. 8–10 AGO 2008. B. Hernández y M. Moraga. Tp. Foso. L_S_ 300700 _569000 #95344. INB0004182326.

Habitat. The species has been collected with a pitfall trap at an altitude varying from 1100–1200 m, during the month of August. Ateuchus alutacius was collected in a cloud forest on the southern slope of the Fila Costeña, in an approximately 10 ha sized forest remnant, surrounded by cattle pasture and grasslands.

Geographical distribution ( Fig. 14 ). This species is known from the Pacific slope of the Fila Costeña of Costa Rica.

Chorological affinities. Ateuchus alutacius is found at similar altitudes at the Fila Costeña as its ecological equivalents, small dung tunnellers living in cloud forests, in Guanacaste ( Ateuchus earthorum Kohlmann & Solís , A. fetteri Kohlmann , and A. hendrichsi Kohlmann ) and Central Cordillera ( A. ginae Kohlmann) (Kohlmann 1997) .

This is the first brachypterous species described in the genus Ateuchus . It is also the fifth flightless species of Scarabaeinae recorded for Costa Rica. The other known species are: Canthidium planovultum Howden & Young , collected on the Pacific slopes of the Central and Talamanca Cordillera and also present in Panama ( Solís & Kohlmann 2004); Cryptocanthon lindemanae Howden & Gill , collected on the Pacific slope of the Tilarán Cordillera in Monteverde ( Cook 2002); and Onthophagus inediapterus Kohlmann & Solís and Onthophagus micropterus Zunino & Halffter , collected on the Pacific slope of the Talamanca Cordillera ( Kohlmann & Solís 2001). All these species have in common that they live in mountain cloud forests, which apparently supports the theory that flightlessness increases with altitude in temperate forests in the tropics ( Scholtz et al. 2009).

Regarding habitats, flightless dung beetles are not well represented in tropical forests ( Scholtz et al. 2009). In Costa Rica, flightless dung beetles are associated with cloud forests in tropical mountains, not with tropical forests in the lowlands. It is argued that habitat stability is a key factor favouring the loss of flight (Roff 1990, Scholtz 2000). Following this train of thought, it would seem then that cloud forests represent such stable habitats and not the rain forests.

An analysis of species and endemicity richness, reported by Kohlmann (2011), concluded that cloud forests are somewhat richer than lowland tropical rain forests in Costa Rica on both counts. This aspect contradicts Scholtz’s (2000) hypothesis that flightless dung beetles occur at higher rates in temperate forests at high altitudes in the tropics, where these environments are relatively species-poor and thus lack complex biotic interactions. This is not the case for Costa Rican cloud forests, which are very species-rich.

Wagner & Liebherr (1992) present an analysis of flightlessness in insects, where it is calculated that around 10% of temperate Coleoptera species show this characteristic. Based on our current tally, 181 Scarabaeinae taxa have been listed for Costa Rica. It would seem then that the percentage of flightlessness of tropical dung beetle species in Costa Rica (2.7%) is below the percentage registered for temperate Coleoptera . This finding would seem to support the hypothesis that dung-beetle flightlessness increases with latitude ( Scholtz et al. 2009).

Finally, Scholtz et al. (2009) indicate that flightless species of dung beetles tend to develop a rounded shoulder (humeral angle) and a globose body. Costa Rican flightless species are certainly globose in body shape, but they all have a sharply angled shoulder like their winged beetle counterparts. This could be probably explained by the fact that these species are of recent evolutionary origin.

Taxonomic relationships. More material is needed, especially males, and an actual phylogenetic analysis, in order to establish taxonomic relationships. Presently, and using the similar eye shape and the shagreened elytra and pygidium, the new species would seem to have a certain degree of affinity with A. candezei Harold. It is the only North and Central American species known so far to the authors that has shagreened abdominal sternites, as well as being the only brachypterous Ateuchus species described so far.

This species will key to A. candezei in Kohlmann’s (1997) key. However, the two species are easily separated by the following combination of characters: In A. alutacius , both the pygidium and sternites are heavily shagreened and black in color; in A. candezei , only the upper part of the pygidium is shagreened, and the pygidium and the sternites are reddish brown. Additionally, the base of the thorax is not shagreened in A. alutacius , while the thorax base of A. candezei is shagreened. Finally, A. alutacius is brachypterous, the first recorded Ateuchus to show this characteristic.

With the description of this new species of Ateuchus , the total number of species reported from Costa Rica increases from 10 ( Kohlmann & Solís 2009) to 11.

Etymology. Alutacius , Latin adjective in the genitive case, referring to the leathery appearance of this species.

Figures

FIGURE 4. Dorsal habitus of the female holotype of Ateuchus alutacius Kohlmann & Solís, new species.

FIGURE 14. Known distribution of Ateuchus alutacius Kohlmann & Solís, new species (circle) and Onthophagus turgidus Kohlmann & Solís, new species (triangle). Base map from Google Maps.

FIGURE 5. a. Dorsal view of left wing of Ateuchus candezei; b. Dorsal view of brachypterous left wing of the holotype of Ateuchus alutacius Kohlmann & Solís, new species.