Phanaeus (Notiophanaeus) dionysius Kohlmann, Arriaga-Jimenez & Roes

Kohlmann, Bert, Arriaga-Jimenez, Alfonsina & Roes, Matthias, 2018, Dung beetle vicariant speciation in the mountains of Oaxaca, Mexico, with a description of a new species of Phanaeus (Coleoptera, Geotrupidae, Scarabaeidae), ZooKeys 743, pp. 67-93 : 69-73

Phanaeus (Notiophanaeus) dionysius Kohlmann, Arriaga-Jimenez & Roes sp. n. Figures 1, 2, 3, 4, 5, 6

Type material.

Holotype male, pinned, with genitalia in a separate microvial. Original label: “México. La Mesita San Pablo Etla. Oaxaca.

23-VI-17, coprotrampa, 17°9'54"N, 96°44'18"W, bosque de Encino, 1976 m, Arriaga A. and Arenas A. Col." "HOLOTYPE/ Phanaeus dionysius Kohlmann, Arriaga-Jiménez, Rös [red printed label]". Allotype female: "Mexico. La Mesita San Pablo Etla. Oaxaca. 23-VI-17, coprotrampa, 17°9'54"N, 96°44'19"W, bosque de Encino, 1976 m, Arriaga A. and Arenas A. Col."

Other material.

(5 males, 5 females). Paratypes: "Mexico. Reserva Comunitaria San Pablo Etla. Oaxaca. 27-IV-17, coprotrampa, 17°9'53"N, 96°44'20"W, bosque de Encino, 1974 m, Arriaga A. and Arenas A. Col." (1 males, 2 females) (CMN, CEMT, CPFA); "Mexico. La Mesita San Pablo Etla. Oaxaca. 23-VI-17, coprotrampa, 17°9'54"N, 96°44'18"W, bosque de Encino, 1976 m, Arriaga A. and Arenas A. Col. (2 males, 2 females) (CMN, CEMT, IEXA, CPFA); 14-VII-17, 17°9'54"N, 96°44'54"W, 1954 m, (1 male) (IEXA); 27-IV-17, 17°10'16"N, 96°43'50"W, 2219 (1 male) (JB). 23-VI-17, 17°09'54"N, 96°44'19"W, 1976 m, (1 female) (JB).

Type locality.

La Mesita San Pablo Etla (17°9'54"N, 96°44'19"W, 1976 m), Oaxaca, Mexico.

Type deposition.

Colección Entomológica IEXA, Instituto de Ecología, Xalapa, Mexico.

Diagnosis.

Distinctly granulate male pronotal disk; sagittal furrow present on the female pronotum; unmodified sutural margin of the elytra; pygidium longer than wide. Its basal border forming a small indentation medially, usually all-black color.

Description.

Holotype. Major male (Fig. 1 a–b). Length: 16.5 mm. Humeral width: 10. 9 mm. Body appearing dull shiny black with a faint blue luster to the unaided eye. Magnification reveals faint greenish cast along the ocular, pronotal, and elytral borders, on the abdominal surface and underside of femora rugose. Clypeus with two conspicuous median teeth; surface and frons bearing long, slender horn strongly curved over the pronotum. Pronotum with large, flat triangular disk (Fig. 1a), with a well-developed, small callosity on each side near anterior margin and with postero-lateral angles projecting caudally; lateral portions faintly asperate, with distinct punctures present only behind lateral fossae ( × 20); flat triangular surface disk densely, evenly, and coarsely granulate; granules extending onto posterolateral angles and becoming eroded near and along disk borders. Pronotum with obsolete basal fossae; anterolateral angles subquadrate, distinctly upturned and surface behind angles concave; pronotal midline present, faintly developed, more evident on anterior half; weak punctures along posterior pronotal margin; pronotal surface shagreen. Elytral striae fine, with small but well-defined punctures separated at regular intervals; intervals broad and faintly convex, evenly and faintly shiny, covered with minute punctures ( × 20); surface shagreen. Pygidium black with shagreen surface and obsolete punctures, glabrous; pygidium wider than long (Fig. 2a); basal pygidial margin forming a small triangular tooth medially (Fig. 2b); pygidial margin with a green cast. Protibia quadridentate. Lamella copulatrix as in Figure 3a; aedeagus similar to the Ph. endymion species group (Fig. 3b, d).

Female. Allotype (Fig. 4). Length: 16.3 mm. Humeral width: 10 mm. Body faintly shining black. Head with low, narrow trituberculate carina. Pronotum with a faint green lustre, evenly and densely covered with punctures, punctures becoming fainter on middle of disk; surface shagreen; with raised anteromedian trituberculate tumosity near anterior margin, tubercles equal in size and set in a more-or-less straight, transverse line; disk with distinct mid-longitudinal furrow, extending forward from posterior margin to about middle of disk, furrow more strongly sculptured than adjacent surface of disk. Pygidium with faint to distinct fine, sparse punctures.

Variations.

Length: 12.6-18.7 mm. Humeral width: 7.9-11.1 mm. Pronotal disk of males may vary from black without reflections to having a green or red lustre. Minor male (Fig. 5): Similar to major male, except the cephalic horn is smaller and the posterolateral angles of the pronotum are reduced.

Etymology.

Due to the fact that this species has been collected in association with Ph. damocles Harold, this new species (a noun in the nominative singular) is named after Dionysius II of Syracuse, one of the main characters alluded to in the moral anecdote of the "Sword of Damocles".

Distribution and ecology.

So far, this species is only known from San Pablo Etla in the Sierra Norte (Sierra de Ixtlán) in Oaxaca (Fig. 6), along the internal dry slope facing the Oaxaca Valley. It has been collected from altitudes of 1950 m to 2250 m. The dry deciduous oak forest where Phanaeus dionysius sp. n. was found is characterised by trees between five and ten meters tall. Abundant oak species are Quercus laeta Liebm. and Q. laurina Humb. and Bonpl., predominant species of this ecosystem, ranging from 1800 m to 2400 m altitude (Fig. 7). Other species dominating this forest in the sampling site are Q. glaucoides Mart. and Gal., Q. liebmannii Oersted., Q. rugosa Née, and Q. castanea Née, also found at higher or lower altitudes (J. Williams, CIIDIR-Oaxaca, pers. comm., Valencia-Ávalos and Nixon 2004). This dry deciduous oak forest shows a strong seasonality, when most trees lose their leaves for around four to five months between December and May. This new species is found next to the Oaxaca Metropolitan Area in a voluntary protected area, the San Pablo Etla Community Reserve "La Mesita".

Phanaeus dionysius sp. n. has been collected simultaneously in dung-baited traps with Canthidium quercetorum Kohlmann, Arriaga-Jiménez and Rös, Canthon humectus (Say), Copris klugi Harold, Deltochilum mexicanum Burmeister, Dichotomius colonicus (Say), Onthophagus near anthracinus Harold, O. aureofuscus Bates, O. chevrolati retusus Harold, O. mexicanus Bates, O. zapotecus Zunino and Halffter and Phanaeus damocles Harold, in the oak forest. Although its closest relative, Ph. zapotecus Edmonds, seems to be a strictly mycetophagous species, Ph. dionysius has only been collected in dung, despite the presence of fungi-baited traps put in the forest. Interestingly, no big fleshy fungi (toadstools) were observed in this type of forest, only small “clavitos” ( Lyophyllum ), which could probably explain why this species does not exploit fungi.

Taxonomic relationships.

Phanaeus dionysius sp. n. belongs to the Ph. endymion species group and due to its close taxonomic similarity discussed below is postulated to be the sister species of Ph. zapotecus Edmonds, 2006. Phanaeus dionysius will key out to Ph. zapotecus in the key of Moctezuma et al. (2017) and can be separated from it because it has long and slender pronotal posterolateral angles (Fig. 1a) whereas Ph. zapotecus has short and rounded posterolateral angles (Fig. 1c). The basal border of the pygidium in Ph. dionysius forms a small indentation at its middle (Fig. 2b), whereas it runs completely straight in Ph. zapotecus (Fig. 2c). Additionally, the apex of the parameres of Ph. dionysius sp. n. is more projected (Fig. 3b, d), than that from Ph. zapotecus (Fig. 3c, e). Moreover, the middle sinuation of the parameres in lateral view is much more pronounced in Ph. dionysius sp. n. (Fig. 3b) than in Ph. zapotecus (Fig. 3c).

Chorological affinities.

The known distribution of Ph. dionysius sp. n. is relatively near to its closest relative, Ph. zapotecus , 90 km distance in a straight line, which is distributed in dry pine-oak and pine-oak-juniper forests on the internal slope of the Sierra Sur (Sierra de Tlaxiaco), going from 1850 m to 2150 m altitude. Interestingly, attempts at trying to collect Ph. zapotecus in the environs of San José del Pacífico in the Sierra Sur (Sierra de Miahuatlán) with fungi-baited traps did not produce any results.