Ateuchus tuza Kohlmann and Vaz de Mello, 2018

Kohlmann, Bert & Vaz-de-Mello, Fernando Z., 2018, A new key for the species of Ateuchus Weber (Coleoptera: Scarabaeidae: Scarabaeinae) occurring in Mexico, with a description of the first North American inquiline species from a rodent burrow (Rodentia: Geomydae) and new distribution records, Revista Brasileira de Entomologia 62 (2), pp. 131-134 : 132-133

Ateuchus tuza Kohlmann and Vaz de Mello , sp. nov.

( Figs. 1–4 )

Type locality: MEXICO: VERACRUZ, Dos Amates (Catemaco), elev. 300–600 m (18 ◦ 29 Ɩ 21 ƖƖ N, 95 ◦ 03 Ɩ 35 ƖƖ W)

Diagnosis. This species is distinguished from other Ateuchus species by the following combination of characters: Long and slender body; dorsum glossy; clypeus bidentate; head simply convex, lacking carina or tubercle; base of the head with a small wrinkled area in the center; anterior border of pronotum continuous, posterior border of pronotum with an area of dense and coarse punctures medially; elytral lateral portion rounded; sternellum forming a carina in the middle; pygidium slightly convex, lightly shagreen, and inconspicuously punctate.

Description. Holotype male ( Figs. 1–4 ). Body. Elongate ( Figs. 1–2 ), convex dorsally ( Fig. 1 ). Size. Total length 10.0 mm. Maximum width 5.5 mm. Color. Dark reddish brown to black, lacking metallic sheen. Head. Clypeal margin anteriorly broadly V-shaped ( Figs. 1–2 ); anterior margin slightly upturned, gena and frons coarsely wrinkled, vertex coarsely punctate, base of head with a small wrinkled area in the center ( Fig. 3 ), eyes viewed from above six times longer than wide. Pronotum. Transverse, strongly convex, surface glossy; anterior pronotal margin complete; midline weakly impressed at base; pronotal surface punctate throughout, a group of coarse punctures at the center of the pronotal base ( Fig. 1 ); lateral pronotal fossae shallow. Elytra. ( Fig. 1 ). Striae fine, shallowly impressed on disk, becoming well defined and deeply impressed on apical declivity; strial punctures elongatecrenulate, slightly wider than stria, separated by 2–3 diameters on disk and apical declivity. Interstriae slightly convex on disk, surface minutely punctate throughout. Thoracic sterna. ( Fig. 2 ). Proepisternum excavate anteriorly, surface of excavated portion granulate, with fine and rather long setae, bordered posteriorly by a well-defined keel. Proepimeron finely wrinkled. Sternellum glabrous and forming a keel at its center. Mesometasternal suture arched medially, marginal bead fine. Mesosternum coarsely punctured forming rugulae. Mesepisternum flat, surface-forming rugulae. Metasternum evenly convex, disk evidently punctate, surface glossy between punctures, lateral lobes forming rugulae; midline clearly impressed along three fourths of its length. Legs. ( Figs. 1–2 ). Foretibia with four teeth on outer margin, the basal one weakly developed; foretibial spur expanded and truncate apically; foretibiae and forefemora long and slender; forefemur smooth, finely punctate throughout. Metatibiae obliquely truncate apically; apical spur spiniform. Abdomen. ( Fig. 2 ). Sternites 3–7 crenulately punctate along their anterior borders. Last abdominal segment slender. Pygidium slightly convex and lightly shagreen with indistinct punctuation; basal sulcus fine and deep throughout; marginal bead continuous. Male genitalia. Parameres simple, tapering to apex in lateral view, apical portion rounded in dorsal view. The internal sac of the aedeagus with three hooks, two spine-like and one spoon-like ( Fig. 4 ).

Allotype: Female. Total length 9.5 mm. Maximum width 5.0 mm. Same as male with the following sexual differences: clypeal margin anteriorly, not so broadly V-shaped; lateral pronotal margin not arched; last abdominal segment broader medially; foretibiae and forefemora shorter and foretibial spurs slender and slightly bent at tip; pygidium not as long.

Variation: Total length 9.5– 10 mm. Maximum width 5.0–5.5 mm. Material examined (34 specimens): Holotype. Male: México: Veracruz: Dos Amates ( Catemaco ), 8– V–1968, P. Reyes, M. Cabrera cols. Nido de tuza. Cámara de desechos ( CEMT). Allotype. Female: ibidem, one female. Paratypes. ibidem, six males, four females (three males and three females at CEMT; one male, Gonzalo Halffter personal collection, Coatepec, Mexico; one male and one female at Bert Kohlmann personal collection, Las Mercedes de Guácimo , Costa Rica; one male to be deposited at Canadian Museum of Nature , Ottawa , Canada) ; one male, one female, Entomological Collection at the Institute of Ecology, Xalapa, Mexico ( IEXA), México: Oaxaca, Sta. María Chimalapas , 12-VI-2015 , colecta directa, dentro de madriguera de tuza, J. Luis S. Huerta col.; five males, seven females, ibidem, 16-VI-2015; two males, two females, ibidem, 18-VI-2015; one male, one female, ibidem, 19-VI-2015; two females, ibidem, 22-VI-2015.

Remarks: This is the first North American inquiline Ateuchus species collected from a pocket gopher burrow.

Etymology: The name tuza , a name in apposition, is the hispanized common name of the indigenous nahuatl word tozan, given to the beaver-looking subterranean rodent, where the new Ateuchus species was found.

Geographical distribution: The new species is so far only known from the locality of Dos Amates, Catemaco, in the state of Veracruz , and the locality of Santa María Chimalapas, Oaxaca, Mexico .

Habitat: The new species was collected in the waste chamber of a pocket gopher ( Rodentia : Geomydae) burrow during the month of May. Although the rodent of the original collection site was not identified at the time, it is most likely that the specimens were found inside the nest of Orthogeomys hispidus (Le Conte) .

Chorological affinities: Interestingly, this new Ateuchus species is found under similar ecological conditions, a lowland tropical area, as Ateuchus cujuchi Génier , the other known inquiline rodent burrow Ateuchus species from Bolivia ( Génier, 2015). A. cujuchi was collected in a Ctenomys burrow, a rodent belonging to a different family, Ctenomydae, as the one collected in Mexico.

Taxonomic relationships: The shape of the body of this species resembles the South American species apicatum (Harold, 1867) and is clearly not related to the known body shape of the North or Central American Ateuchus species. The new species will key to couplet 23/24 ( apicatum ) in Balthasar’s (1939) key. It can be easily separated from A. apicatum because of the presence of the small rugose area at the center of the base of the head and the presence of coarse punctures at the middle of the pronotal base. This taxonomic relationship would suggest that Ateuchus species derived of South American lines have adapted to and colonized lowland gopher nests in North America; whereas, in the mountainous areas of North America it is species of the genus Onthophagus , which has adapted to colonizing gopher nests ( Anduaga and Halffter, 1991; Lobo and Halffter, 1994; Zunino and Halffter, 2007).

This new species shows adaptations to living in an environment devoid of light, like the subterranean gopher nest. First, the dorsal eye area is very small. Second, the aforementioned rugose area at the base of the head is a stridulation mechanism, similar to those found at the base of the head of Uroxys , as found in U. microcularis Howden and Young , U. micros Bates and U. platypyga Howden and Young ( Delgado and Kohlmann, 2007; Solís and Kohlmann, 2013), and most probably helps in the communication process of this species.

Figures

Figures 1–3. Ateuchus tuza sp. nov.; 1, dorsal habitus of holotype; 2, ventral habitus of holotype; 3, wrinkled area at the base of the head of a male.

Figures 4–5. A. tuza sp. nov.; 4, drawing of the internal sac, line equals 1 mm; 5, A. hornai (Balthasar, 1939), dorsal habitus of the female holotype.