Onthophagus chimalapensis Delgado & Mora-Aguilar, 2019

Delgado, Leonardo & Mora-Aguilar, Eder F., 2019, A new Mexican species of Onthophagus Latreille (Coleoptera: Scarabaeidae: Scarabaeinae), with a revised key to the species of the O. dicranius species complex, Zootaxa 4695 (6), pp. 586-592 : 586-590

Onthophagus chimalapensis Delgado & Mora-Aguilar , new species

( Figs. 1–8 , 13, 16 , 19 )

urn:lsid:zoobank.org:act:185F1648-2A1D-4C43-AAEA-755085B823B6

Type material. Holotype male, and one female paratype labeled: “ MEXICO: Oaxaca, San Miguel Chimalapa, San Antonio, El Retén , Camino a la Torre, 16º 39′ 50.9” N, 94º 14′ 0.2” W, 26-VII-2017, Winkler , 1,800 m, bosque mesófilo, E. Arriaga-Varela, F. Alvarado, E. Mora-A. cols.” One male paratype with the following data: “ MEXICO: Oaxaca, San Miguel Chimalapa, San Antonio, El Gringo, 16° 40′ 43” N, 94° 15′ 46” W, VI-VII-2013, Trampa de Intercepción , 1,600 m, bosque mesófilo, E. Mora-A., L. Delgado cols.”.

Holotype and one female paratype are deposited in IEXA, the male paratype deposited in CNIN.

Holotype Male. Body size. Total length: 6.0 mm; width: 3.5 mm. Colour. Dorsum shiny, dark brown; margins of head, femora, and tibiae reddish brown; apex and lateral margins of elytra up to the level of posterior margin of first sternite yellowish orange. Antennae reddish brown ( Figs. 1, 3, 5 ). Head. Clypeus concave, frons and vertex slightly convex. Surface of head with small, simple, or weakly annulate fine and sparse punctures, more accentuated near the margins. Clypeus armed with an apical horn slightly recurved backward; basal portion of horn wide and flat, tapering towards the rounded apex, sides parallel. Clypeal surface adjacent at the base of the horn concave; genae lobed, narrowed to the ocular canthus; clypeo-genal junction emarginate. Thorax. Pronotum with a feeble anteromedian protrusion marked by 2 lateral tubercles separated by a central concavity; anterolateral pronotal declivities concave; anterolateral edges of pronotum rounded. Pronotal disc with small, simple, or weakly annulate, sparse punctures; most punctures separated by more than 2 puncture diameters; punctures towards lateral and apical margins becoming larger, annulate, and denser. Metasternum gradually descending to mesosternum, with fine and moderate-sized punctures, denser and larger near the margins. Elytral striae distinctly impressed; with small, weakly annulate punctures separated by 2 – 3 puncture diameters; elytral intervals finely rugulose, with small, weakly annulate punctures, separated by 2 – 3 diameters. Abdomen. Pygidium convex, coarsely punctate; punctures annulate, confluent on disc, and each bearing a minute seta. Legs. Protibiae elongate, apex with internal angle slightly protruded, anterior edge with tuft of long setae, the two apical teeth separated from their base ( Fig. 7 ); apex of metatibia with setae mostly stout and short, and with some fine and long setae between them. Genitalia. Parameres moderately short, with apex slightly rounded in frontal view, acuminate and directed downward in lateral view ( Figs. 7–8 ).

Paratypes (one male and one female). Total length: 5.3–5.8 mm; width 3.1–3.5 mm. The female differs from holotype in the following respects: clypeus unarmed, sharply bidentate, teeth slightly reflexed and separated by a V-shaped notch, lateral margins of teeth slightly oblique, lateral clypeal margin slightly curved; clypeus flat, with surface irregularly wrinkled; clypeofrontal suture with a sharp and straight carina, not reaching the lateral borders; frons with indistinct swellings in front of the eyes; pronotum nearly rounded in dorsal view, evenly convex, except for the pronotal disc which has a rounded, flat surface anteriorly; protibiae robust, lacking tuft of apical setae and with the inner angle not protruded ( Figs. 2, 4, 6 , 16 ). The male paratype differs from the holotype because of the smaller size and the following sets of characters: profemora and mesofemora, apex and lateral margins of elytra darker; clypeal horn slightly shorter, genae less expanded; pronotal protrusion weaker, with tubercles shorter, and anterolateral declivities less concave. Punctation varies little in density and depth in both sexes. Other characters are similar to holotype.

Etymology. The specific epithet is derived from Chimalapas, the region of the state of Oaxaca where this species was collected, combined with the Latin suffix – ensis, meaning belonging to.

Distribution. Onthophagus chimalapensis is known from two neighbouring localities, in the highly conserved mountainous areas of El Retén in the Chimalapas region, in the State of Oaxaca, Mexico ( Fig. 19 ). Both localities and surrounding areas have a rugged topography with ravines and hills with moist cloud forests ranging from about 1,450 m to 1,800 m. The cloud forests of the Chimalapas region are separated from the cloud forests of the Meseta Central de Chiapas and the Sierra Madre de Chiapas by drier lowlands.

Taxonomic remarks. Onthophagus chimalapensis ( Figs. 1–8 ) is similar to O. subcancer Howden ( Figs. 9–12 ), as both species share the following characters: length less than 7 mm; colour dark brown lacking metallic iridescence; elytra with apex yellowish red; mesofemora and metafemora light brown or yellowish red ( Figs. 1–4 ); dorsum glabrous, punctures of the pronotal disc simple or weakly annulate, small, and sparse; pygidium coarsely punctate; protibiae with the two apical teeth widely separated (joined only at the base); clypeal horn of male recurved; head lacking of carinae, tubercles, or horns between the eyes; clypeus of female bidentate at middle; clypeofrontal suture with a central carina; frons without carina or tubercles behind of eyes.

The new species differs from O. subcancer by the following characters: male with frons and vertex convex and finely punctate (not flat and with distinct, moderate-sized punctures) ( Figs. 5 , 9 ), female with frons without tubercles (not with two tubercles at level of the anterior border of eyes), and pronotal disc with a rounded, slightly concave surface anteriorly (not evenly convex) ( Figs. 6 , 10 ). This combination of characters is diagnostic to the new species. The size and shape of the pronotal protrusion observed on the holotype and male paratype of O. chimalapensis show seemingly a moderate development.

Many of the characters shared between O. chimalapensis and O. subcancer are also shared with the species of the O. dicranius species group (sensu Kohlmann & Solís 2001). In fact, Zunino & Halffter (1997) had included O. subcancer into the O. mirabilis species set of the O. clypeatus group. Likewise, Howden & Gill (1987) also mentioned the similarity of O. dicranius and O. dorsipilulus Howden & Gill to O. subcancer . Morphological differences of both O. subcancer and O. chimalapensis with the species of the O. dicranius species group are basically related to punctation: the punctures of the pronotal disc are sparse, simple, or weakly annulate and fine (punctures not annulate and/or large, and dense in the species of the O. dicranius species group); while the elytral striae have annulate and small punctures (not annulate and/or large punctures in the species of the O. dicranius species group).

Since the separation of the O. dicranius and O. mirabilis species groups from the O. clypeatus species group by Howden & Gill (1993), there have been different views in considering only one or two groups. Génier & Howden (1999) redefined these groupings by using the colour of the body, structure of protibiae, and morphological differences observed on the head and pronotum of females. As suggested by Génier & Howden (1999) and more recently by Génier (2017), we consider the O. dicranius and O. mirabilis as species complexes within the O. dicranius species group. In this regard, O. subcancer and O. chimalapensis are placed into the O. dicranius species complex, as both species exhibit the body bicolored, and the two apical teeth of protibia widely separated (joined only at the base); not the body concolor, and the two apical teeth of protibia joined beyond the base ( Figs. 13–18 ). However, females of these two species, like the species of the O. mirabilis species complex, show remarkable differences on head and pronotum ( Figs. 2, 4, 6 , 10 ). Thus, the O. dicranius species complex comprises the following species: O. asperodorsatus Howden & Gill , O. chimalapensis , O. cryptodicranius Kohlmann & Solís , O. dicranius , O. dorsipilulus , O. inediapterus Kohlmann & Solís , O. kohlmanni Génier , O. nubilus Kohlmann & Solís , O. petenensis Howden & Gill , O. quetzalis Howden & Gill , and O. subcancer ( Howden & Gill 1993; Génier & Howden 1999; Kohlmann & Solís 2001; Génier 2017). Although Onthophagus quetzalis was initially considered into the O. mirabilis species complex ( Howden & Gill 1993), after was included in the O. dicranius species complex by Génier & Howden (1999) this change was supported by the morphological characters previously mentioned. Unlike Kohlmann & Solís (2001), we remove from this complex Onthophagus micropterus Zunino & Halffter , as males and females have conspicuous tubercles aligned with the midline of the eyes, not head destitute of tubercles or horns at this region, as in the others species of the O. dicranius species group.

Figures

FIGURE 19. Distribution of Onthophagus species. Onthophagus chimalapensis new species (circle), O. subcancer (square). Soft to dark grey lines represent elevational gradients of 1,000, 2,000, and 3,000 m, respectively.

FIGURES 1–8. Onthophagus chimalapensis. 1, Habitus, holotype; 2, habitus, female paratype; 3, lateral view of male paratype; 4, lateral view of female paratype; 5, ¾ profile view of male holotype; 6, ¾ profile view of female paratype; 7, lateral view of genitalia, male paratype; 8, dorsal view of genitalia, male paratype.

FIGURES 9–18. Onthophagus species. 9, ¾ profile view, male of O. subcancer; 10, ¾ profile view, female of O. subcancer; 11, lateral view of genitalia, male of O. subcancer; 12, dorsal view of genitalia, male of O. subcancer; 13, protibia of O. chimalapensis, holotype; 14, protibia of O. aperodorsatus, male paratype; 15, protibia of O. neomirabilis, male; 16, protibia of O. chimalapensis, female paratype; 17, protibia of O. asperodorsatus, female; 18, protibia of O. neomirabilis, female.