In 2009, my colleague Robert S. Anderson collected a male and a female Onthophagus Latreille, 1802 (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini) from the cloud forest of Cerro El Pinalón (El Progresso Department, Guatemala). The male specimen was similar to O. neomirabilis Howden, 1973, which occurs in southern Mexico and Guatemala, but the configuration of the females pronotum was unlike any of the females currently known belonging to the O. mirabilis species complex. At the time, those specimens were put aside in the hope that more material would become available to confirm that the female pronotal configuration was not the result of a deformity. Then in 2015, a specimen lot of Guatemalan scarabaeine was conveyed to the author for identification. Among this material were 16 males and six females matching the two previously known specimens collected at Cerro El Pinalón. Interestingly, the specimens collected in 2015 were from Volcán Atitlán, which belongs to a different Guatemalan mountain range. Species from the O. mirabilis species complex are restricted to higher elevations and specifically cloud forest, which form a more-or-less disjunct biome (Zunino and Halffter Reference Zunino and Halffter1981).

The O. mirabilis species complex was revised less than 20 years ago (Génier and Howden Reference Génier and Howden1999), at that time only the female of O. mirabilis Bates, 1887 was unknown but it was discovered and described five years later (Génier and Medina Reference Génier and Medina2004). More recently, a new species belonging to the complex was described from Panama (Kohlmann and Solís Reference Kohlmann and Solís2012). The description of O. turgidus Kohlmann and Solís, Reference Kohlmann and Solís2012 was based on a single male specimen, and is most similar to O. solisi Howden and Gill, Reference Howden and Gill1993. To date, females of this species are still unknown. Because the taxonomy of the entire O. mirabilis species complex is resolved, the description of a single species presented here in this context seems warranted. The cephalic and pronotal configurations of well-developed, known females belonging to this complex are also illustrated by photographs for the first time.

In Génier and Howden (Reference Génier and Howden1999), the O. mirabilis species complex was considered a species group. Here, a species complex is a group of closely related species that are very similar in appearance to the point that the boundaries between them are often unclear, as seen in the external morphology of the males. A species group has a broader scope and encompass species that possess one or more synapomorphies and may have very distinctive external morphologies. This grouping (Génier and Howden Reference Génier and Howden1999) was essentially based on Howden and Gill (Reference Howden and Gill1993) in which two groups were defined, the O. mirabilis species group (O. mirabilis Bates, 1887, O. neomirabilis Howden, 1973, O. quetzalis Howden and Gill, Reference Howden and Gill1993, and O. solisi Howden and Gill, Reference Howden and Gill1993) and the O. dicranius species group (O. asperodorsatus Howden and Gill, Reference Howden and Gill1993, O. dicranius Bates, 1887, O. dorsipilulus Howden and Gill, 1987, and O. petenensis Howden and Gill, Reference Howden and Gill1993). Howden and Gill (Reference Howden and Gill1993) considered O. quetzalis to be in some measure intermediate between their O. mirabilis and O. dicranius species groups. Zunino and Halffter (Reference Zunino and Halffter1981, Reference Zunino and Halffter1997) always considered all species belonging to the two groups defined by Howden and Gill (Reference Howden and Gill1993) to be part of a larger group encompassing more than 20 species known as the O. clypeatus species group. The main character defining the O. clypeatus species group as defined by Zunino and Halffter (Reference Zunino and Halffter1981, Reference Zunino and Halffter1997) is the absence of a secondary lamella associated with the lamella copulatrix, which correspond to the additional medial sclerite of lamella copulatrix in Tarasov and Solodovnikov (Reference Tarasov and Solodovnikov2011). The O. mirabilis species complex as treated here is considered to be part of the more restricted group defined by Kohlmann and Solís (Reference Kohlmann and Solís2001) as the O. dicranius species group. The O. dicranius species group of Kohlmann and Solís (Reference Kohlmann and Solís2001) comprises all species included in the O. dicranius and O. mirabilis species groups of Howden and Gill (Reference Howden and Gill1993). The species group possesses the following combination of characters: males lack carina on vertex, as well as a trace of tubercle or horn adjacent to the eyes; females have a strongly upturned, bidentate anterior clypeal edge and transverse carinae or conical tubercles are located at midpoint or anterior (but not posteriorly) to the eyes (with the exception of O. barretti Génier and Howden, Reference Génier and Howden1999, where the cephalic horns are located posterior to the anterior edge of the eyes); both sexes have moderate to large punctures separated by <1.0–1.5 puncture diameters with the elytral striae and interstriae coarsely punctate; all the species have a rugose punctate pygidium, especially towards apex; colour varies from brown to black, and no species have metallic iridescence, which is present in most species of the O. clypeatus species group. The paramere shape is similar for all species in the O. mirabilis species complex and has been illustrated by Howden and Gill (Reference Howden and Gill1993) for O. neomirabilis (Fig. 28), O. orphnoides (as O. mirabilis) (Fig. 21), and O. solisi (Fig. 24).

The specimen preparation, imaging procedures, and format used is the same as Génier and Moretto (Reference Génier and Moretto2017). The terminology used for the lamella copulatrix follows Tarasov and Solodovnikov (Reference Tarasov and Solodovnikov2011). The following collection acronyms are used: CMNC, Canadian Museum of Nature, Ottawa, Ontario, Canada; SEMC, Kansas University Entomology Collection, Lawrence, Kansas, United States of America (Zachary H. Falin); UVGC, Colleción de Artrópodos, Universidad del Valle de Guatemala, Guatemala City, Guatemala (Jack Schuster).

Onthophagus contrapositus Génier, new species

(http://zoobank.org/urn:lsid:zoobank.org:act:C691DA96-4AA1-4DB8-8552-F4DF0559DAAB)

Figures 1–5, 18.

Figs. 1–17 Onthophagus contrapositus and other species in the O. dicranius species group. 1. Onthophagus contrapositus male holotype, habitus dorsal view. 2. Onthophagus contrapositus male holotype, head and pronotum lateral view. 3. Onthophagus contrapositus male holotype, lamella copulatrix, frontal view. 4. Onthophagus contrapositus female allotype, head, dorsal view. 5. Onthophagus contrapositus female allotype, pronotum, dorsal view. 6. Onthophagus barretti, female, head dorsal view. 7. Onthophagus barretti, female, pronotum dorsal view. 8. Onthophagus breviconus, female, head dorsal view. 9. Onthophagus breviconus, female, pronotum dorsal view. 10. Onthophagus mirabilis, female, head dorsal view. 11. Onthophagus mirabilis, female, pronotum dorsal view. 12. Onthophagus neomirabilis, female, head dorsal view. 13. Onthophagus neomirabilis, female, pronotum dorsal view. 14. Onthophagus orphnoides, female, head dorsal view. 15. Onthophagus orphnoides, female, pronotum dorsal view. 16. Onthophagus solisi, female, head dorsal view. 17. Onthophagus solisi, female, pronotum dorsal view.

Fig. 18 Known distribution of Onthophagus contrapositus new species.

Type locality. Finca Las Nubes (15.08385, −89.94258, 2574 m), Cerro El Pinalón, El Progresso, Guatemala.

Diagnosis. Known from Guatemala and can only be confused with O. breviconus Génier and Howden, Reference Génier and Howden1999 from which moderate to largest males can be separated by the deeply concave pronotal surface behind anterior lateral angles (Fig. 1); females of O. contrapositus lack the median tubercle bordering the pronotal flat area posteriorly (Fig. 5), surface simply longitudinally concave on midline.

Description. Holotype ♂ (Figs. 1–3). Measurements. length 10.0 mm, greatest width 5.5 mm. Dorsum dark brown. Head. (Figs. 1–2) Surface dorsally irregularly punctate on posterior two-thirds, with a small transverse impunctate surface between the eyes, surface between punctures shiny throughout, except for a small surface adjacent to the eyes. Clypeus with an upright horn on anterior edge medially, basal portion of horn tapering on basal fourth in frontal view, parallel sided medially and slightly diverging apically, apical edge slightly notched, median portion trapezoidal in transverse section, apical third slightly wider posteriorly and gradually narrowed anteroposteriorly towards apex in lateral view; each side of clypeus with narrow but distinct marginal bead, nearly straight in dorsal view from base of horn to clypeogenal suture; clypeal surface deeply concave posteriorly to base of horn; gena with lateral edge slightly rounded posterior to clypeogenal suture, almost straight medially, lateral edge at clypeogenal junction lacking emargination. Vertex with barely indicated tubercles on each side near anterior edge of each eye. Pronotum (Fig. 2). Surface with small irregularly distributed umbilicate punctures on anterior declivous portion, remainder of the surface with moderate coarse umbilicate punctures separated by 1–3 diameters; anterior edge of pronotum slightly upturned medially; with large median conical horn extending over the head, apex of horn flattened dorsoventrally, forming two laterally oriented tubercles, ventral surface of horn lacking longitudinal carina, slightly longitudinally concave; pronotal surface near anterior lateral angles deeply concave; posterior marginal bead only present medially. Elytra (Fig. 1). Elytral surface glossy between punctures, puncture of intervals weakly defined and slightly irregular in shape, not umbilicate, lacking setae and separated by 1–3 diameters; Elytral striae deeply impressed, strial punctures separated by 1–2 diameters, encroaching on intervals. Pygidium. Surface with confluent coarse umbilicate punctures throughout, surface between punctures shiny to feebly alutaceous. Ventrites. Median lobe of metasternum with few coarse punctures laterally, impunctate medially, feebly sulcate along midline on most of length. Legs. Protibia elongate, apex with internal angle produced into moderately acute tooth, anterior edge with broad tuft of long setae; external apical and penultimate teeth distinctly closer to each other than second to third or third to fourth teeth. All femora with ventral surface finely punctate, punctures evenly distributed, surface between punctures feebly alutaceous on mesofemora and metafemora. Genitalia. Lamella copulatrix of internal sac with a projection on the superior right lobe (SR) (Fig. 3, red arrow), inferior right lobe (IR) gradually tapering apically, inferior left lobe (IL) long, gap between inferior right and left lobe wide and parallel sided on most of length Fig. 3).

Allotype ♀. Measurements. length 9.5 mm, greatest width 5.0 mm. Head (Fig. 4). Clypeus with anterior margin sharply bidentate, teeth reflexed, median emargination shallow, broadly V-shaped, lateral margins of teeth slightly oblique; lateral clypeal margin slightly arcuate, sharp, lacking marginal bead; clypeus flat, with surface irregularly transversely wrinkled; clypeofrontal suture with wide, moderately sharp and sinuous carina reaching clypeogenal suture laterally; gena with surface flat and shiny, irregularly punctate on most of surface, with lateral edge slightly arcuate anterior to lateral angle, widest portion forming blunt angle. Vertex with surface glossy on posterior third, lacking minute punctures, concave, with two rounded tubercles, tubercle in line with anterior edge of eye and closer to the eye than to each other. Pronotum (Fig. 5). Anterior margin upturned medially, disc with a pentagonal and more-or-less flat depression on anterior two-thirds; each side of depression bordered by a subangular protuberance posteriorly, leaving a gap posteromedially; surface of declivity coarsely and irregularly wrinkled; pronotal surface around depression evenly convex, with coarse umbilicate punctures. Elytra. Similar to those of male. Legs. Protibia robust, lacking median tooth and tuft of setae apically. Femora similar to male. Ventrites. Metasternum with median lobe similar to male.

Variation. Size varies from 7.0 to 10.5 mm. All males possess a distinct more-or-less developed conical projection on the pronotum. However the smallest male studied (7.0 mm) has the pronotal surface flat, resembling the female configuration. Such extreme feminisation of the male secondary sexual characters has only been seen in this specimen. The smallest males of all the other species in the complex present at most a simply convex pronotum at equal size or smaller. Except for the development of secondary sexual characters and size other characters show little variation.

Primary type data. Holotype ♂ (CMNC): [GUATEMALA: El Progreso/Cerro Pinalón, Finca Las Nubes/2574 m, 15.08385°N 89.94258°W/1-5.V.2009, R. Anderson/cloud forest – various, 2009–016]; [WORLD/SCARAB./DATABASE/WSD00033965] barcode label; [HOLOTYPE ♂/Onthophagus/contrapositus n.sp./dés. F. Génier, 2017] red card.

Material examined. Distribution (Fig. 18). GUATEMALA: EL PROGRESO, Finca Las Nubes, Cerro Pinalón, 2574 m (15°5'1.86"N, 89°56'33.29"W), 1–5.v.2009, R.S. Anderson (2009–16) – 1 ♀, 1 ♂ (holotype, allotype, CMNC); SUCHITEPÉQUEZ, Refugio del Quetzal, Volcán Atitlán, 1670 m (14°33'2.41"N, 91°11'32.46"W), 3–6.vi.2015, Z.H. Falin and F. Carrillo (GUAT1F15 039) – 3 ♂♂ paratypes (SEMC); Refugio del Quetzal, Volcán Atitlán, 1670 m (14°33'2.41"N, 91°11'32.46"W), 6–10.vi.2015, Z.H. Falin and F. Carrillo (GUAT1F15 095) – 2 ♀♀, 5 ♂♂ paratypes (1 ♀, 1 ♂ CMNC; 1 ♀, 3 ♂♂ SEMC; 1 ♂ UVGC); Refugio del Quetzal, Volcán Atitlán, 1670 m (14°33'2.41"N, 91°11'32.46"W), 10–13.vi.2015, Z.H. Falin and F. Carrillo (GUAT1F15 116.5) – 1 ♀, 1 ♂ paratypes (SEMC); Refugio del Quetzal, Volcán Atitlán, 1670 m (14°33'2.41"N, 91°11'32.46"W), 13–16.vi.2015, Z.H. Falin and F. Carrillo (GUAT1F15 148) – 3 ♂♂ paratypes (2 ♂♂ SEMC; 1 ♂ UVGC); Refugio del Quetzal, Volcán Atitlán, 1670 m (14°33'2.41"N, 91°11'32.46"W), 16–18.vi.2015, Z.H. Falin and F. Carrillo (GUAT1F15 161) – 3 ♀♀, 4 ♂♂ paratypes (1 ♀, 1 ♂ CMNC; 3 ♂♂ SEMC; 2 ♀♀ UVGC).

Etymology. Contrapositus (to place in opposition) a Latin adjective pertaining to the configuration of the female pronotum.

Natural history. All specimens were collected in cloud forest between 1670 and 2574 m. All specimens from Volcán Atitlán were taken in flight interception traps. Specimens from Cerro Pinalón were hand collected in cloud forest.

Identification. Large males (8.5 mm and larger) of O. contrapositus will key to O. mirabilis in Génier and Howden (Reference Génier and Howden1999). They can be separated from O. mirabilis externally by the overall more coarsely punctate head dorsal surface and by the deeply concave pronotal surface behind anterior lateral angles (Fig. 1); internally the right superior lobe of the lamella copulatrix bears a denticle (red arrow, Fig. 3).

Females of the O. mirabilis species complex can be identified using the following modified key from Génier and Howden (Reference Génier and Howden1999), which also includes the female of O. mirabilis but lacks the unknown female of O. turgidus: