Onthophagus clavijeroi Moctezuma, Rossini & Zunino

Moctezuma, Victor, Rossini, Michele, Zunino, Mario & Halffter, Gonzalo, 2016, A contribution to the knowledge of the mountain entomofauna of Mexico with a description of two new species of Onthophagus Latreille, 1802 (Coleoptera, Scarabaeidae, Scarabaeinae), ZooKeys 572, pp. 23-50 : 27-34

Taxon classification Animalia Coleoptera Scarabaeidae

Onthophagus clavijeroi Moctezuma, Rossini & Zunino sp. n.

Material examined.

Holotype: male pinned with genitalia in microvial. 1. Label Holotypus (in Spanish) "Mexico, El Pinal, Pue., at 0.3 km from Rincón, 2/VII/13, necrotrap 7n2, x- 97°53'59.8" W, y- 19°8'55.3", shrubby veg., 2704 m a.s.l., Moctezuma J.V.P. Col." (1 ♂ GH). Paratypes: 1 ♂, same label as the holotype; 2 ♂♂, labeled "Mexico, El Pinal, Pue., at 0.3 km from Rincón, 2/VII/13, necrotrap 7n6, x- 97°54'1.1" W, y- 19°8'56.8", oak forest, 2710 m a.s.l., Moctezuma J.V.P. Col."; 2 ♂♂, 1 ♀ labeled "Mexico, El Pinal, Pue., at 0.3 km from Rincón, 2/VII/13, necrotrap 7n7, x- 97°53'59.8" W, y- 19°8'54.3", oak forest, 2704 m a.s.l., Moctezuma J.V.P. Col."; 1 ♀ labeled "Mexico, El Pinal, Pue., at 2.5 km from Rincón, 26/VI/13, necrotrap 5n1, x- 97°55'2.1" W, y- 19°7'46.6", oak forest, 2543 m a.s.l, Moctezuma J.V.P. Col.".

Description.

Holotype. Major male (Fig. 1). Length 9.4 mm, maximum width of pronotum 5.3 mm. Body dark-brown and dull with cupreous casts, antennal club dark grey, body covered with yellow and light setae. Clypeus transversally developed and pentagonal shaped, distinctly concave, with anterior margin widely curved at middle. Head with lateral margins slightly sinuate in proximity of clypeo-genal suture, genae with margins subparallel, genal suture distinct. Clypeal carina absent to very feebly indicated, frontal carina subtrapezoidal with anterior convexity and elevated at middle with a triangular tubercle, frons coarsely punctured, with short and light-yellow setae, forward curved. Clypeus with strong and coarse punctures, punctuation almost confluent, some punctures with a long seta, few and shorter setae near the apex of clypeus. Posterior margin of pronotum with evanescent border, lateral margins straight to barely concave between anterior and median angles. Pronotal protuberance not regularly convex, pronotum distinctly sloped between median tubercles and anterior margin, pronotal protuberance obtusely trapezoidal, anterior tubercles absent, posterior tubercles strong and slightly forward than the middle of pronotum. Pronotal disc with irregular and coarse punctuation, punctures slightly elongated and crowded, pronotal surface between punctures clearly microsculptured, punctures with a long and light seta, pilosity shorter and scattered in proximity of apex of pronotal protuberance. Elytral striae impressed, bright and with medium-sized punctures well-spaced, interstriae flattened with finer punctuation than pronotum, every puncture bears a light-yellow seta, microsculpture evident. Pygidium dull and sericeous at the base, apically bright, pygidial surface with inconspicuous punctuation, punctures with a short and light seta, median and longitudinal part of pygidium bare and lacking significant punctures, microsculpture of pygidium reticular. Apex of pygidium with bigger, transversal and confluent punctures, microsculpture less evident. Foretibiae slender, distinctly curved and slightly wider at apex, apical spur with apex distinctly curved downward.

Parameres and endophallic sclerites: Figs 4-6.

Female (Fig. 3): Clypeus more elongated forward than in male, clypeal carina strong and evenly curved, frontal carina trapezoidal, lateral margins of clypeus straight, apex widely curved, clypeo-genal suture not indicated on lateral margin of the head. Lateral margins of pronotum curved, anterior pronotal protuberance ill-defined, disc of pronotum with two circular and flattened areas. Protibiae distinctly wider and less curved than in male. Female genitalia: Fig. 7.

Variation. Minor male (Fig. 2): Smaller than male, clypeus more distinctly trapezoidal, clypeal carina very weakly indicated and slightly swollen at middle, frontal carina reduced and lacking median tubercle, anterior pronotal protuberance ill-defined to absent, disc with two flattened and circular areas.

Derivatio nominis.

We dedicate this species to Francisco Xavier Clavijero (Port of Veracruz, then New Spain, 9 September 1731 - Bologna, Italy, 2 April 1787), American naturalist who, together with his Chilean contemporary J. I. Molina, contested the ideas of Buffon and Pauw in their famous argument about the New World.

Synthesis of localities of the type material.

MEXICO: State of Puebla, El Pinal mountain, Rincón Citlaltépetl at 0.3 km from Rincón Citlaltépetl, 2704-2710 m a.s.l.; Cerro El Pinal, Santa Isabel Tepetzala at 2.5 km from Rincón Citlaltépetl, 2543 m a.s.l.

Type locality.

Cerro El Pinal, Rincón Citlaltépetl, state of Puebla, Mexico.

Type deposit.

Holotype and one paratype in the GH Collection. Six paratypes in the VM, MR, MZ and MM collections.

Affinities.

Onthophagus clavijeroi belongs undoubtedly to the chevrolati group ( Zunino and Halffter 1988), which is well represented in the MTZ mountains, particularly in the TMVB.

Examination of the external morphology of Onthophagus clavijeroi , with special emphasis on the male and female genital organs, led us to consider that this new Onthophagus of El Pinal is closely related to the species included in the fuscus complex ( Zunino and Halffter 1988), such as Onthophagus fuscus Boucomont and its subspecies (the nominotypic one, Onthophagus fuscus mycetorum Zunino & Halffter, Onthophagus fuscus parafuscus Zunino & Halffter and Onthophagus fuscus canescens Zunino & Halffter), Onthophagus pseudofuscus Zunino & Halffter and Onthophagus semiopacus Harold. The morphological pattern shared among these species appears to support their monophyletic origin, but a profound revision of the fuscus complex is required in order to properly address the identity of the polytypic Onthophagus fuscus and the internal systematics of the complex.

The shape and orientation of the apices of the parameres of Onthophagus clavijeroi and Onthophagus fuscus fuscus are very similar (Fig. 4), but the general shape of the lamella copulatrix (Fig. 6), especially the shape and development of both the internal carina and right branch of the copulatory lamella, allow us to easily distinguish between the two species.

In the female, the ventral sclerotization of the vagina corresponds to the morphological pattern already found within the fuscus complex, although the cephalic branches appear noticeably less developed in Onthophagus clavijeroi (Fig. 7).

Distribution and ecology

(Maps 2-3). The species and subspecies of the fuscus complex are distributed across the mountain ranges that delimit the Mexican High Plateau, including the Sierra Madre Occidental, the TMVB and the Sierra Madre Oriental, with one species in the Puebla-Oaxaca Mountain System (Map 2). According to Zunino and Halffter (1988), the fuscus complex occurs to the north of the Tropic of Cancer, on the continental side of the Sierra Madre Occidental at between 2400 and 3000 m a.s.l. and following the distribution pattern of Onthophagus fuscus fuscus. At the same latitude, but on the Pacific side of the same mountain range, Onthophagus pseudofuscus is found at 2000 m a.s.l. or higher.

As noted in other groups of organisms distributed across the Sierra Madre Occidental and westernmost areas of the TMVB, the distribution of the fuscus complex becomes discontinuous in the proximity of the southern part of the Durango State. This interruption may be due to several factors that are not exclusive of this region, such as an interruption of geographic continuity caused by recent orographic movements, and probably the lack of beetle collection in one of the least studied mountainous areas of Mexico (to date, only one single and isolated capture of Onthophagus pseudofuscus has been reported for that area; see Map 2).

In the TMVB, the fuscus complex is represented by several subspecies of Onthophagus fuscus , such as Onthophagus fuscus canescens and Onthophagus fuscus mycetorum and Onthophagus clavijeroi (easternmost side of the TMVB). Onthophagus fuscus parafuscus is found in the southern part of the Sierra Madre Oriental. In addition to this U-shaped distribution across the mountain ranges that flank the Mexican High Plateau, Onthophagus semiopacus is found southward, in the south-eastern part of the Puebla-Oaxaca Mountain System (Map 2).

It should be noted that recent cladistic analyses conducted by Gutiérrez-Velázquez (2013, unpublished data) support the monophyly of the fuscus complex.

The distribution of this complex, as well as its possible monophyletic origin, the taxonomic relationships among taxa and the geomorphological history of the moun tain ranges may support the hypothesis of a modern (Pleistocene to the present) distribution. To our knowledge, Onthophagus clavijeroi would represent a recent element within the fuscus complex, even considering that so far it is only known on mountains of relatively recent geological configuration.

El Pinal (3280 m a.s.l.) is associated with the mountain La Malinche (4461 m a.s.l., see Map 3) and its geological origin corresponds to the First Period of volcanic activity of La Malinche, which is estimated to have formed approximately 34 000 years ago, during the Late Pleistocene ( Castro-Goeva and Siebe 2007). Further information on the Scarabaeinae of El Pinal is provided below in the Discussion.

Onthophagus clavijeroi was collected between 2543 and 2710 m a.s.l. in areas with primary and secondary oak forest and open habitats with shrubby vegetation and pastures. It was collected exclusively in traps baited with decaying squid. No specimens were collected in traps baited with human excrement or horse dung, nor by direct capture in other different excrement types. This implies that Onthophagus clavijeroi is likely to be necrophagous, a common feeding habit reported in various genera of Neotropical Scarabaeinae beetles, but one that is quite rare in American Onthophagus . It is possible that Onthophagus clavijeroi is also found in the nearby mountain of La Malinche, but systematic sampling using necrotraps remains to be carried out in that area.