Phanaeus tridens Castelnau, 1840

Moctezuma, Victor, Halffter, Gonzalo & Lizardo, Viridiana, 2021, The Phanaeus tridens species group (Coleoptera: Scarabaeoidea): a dung beetle group with genital morphological stasis but a changing ecological niche, Acta Entomologica Musei Nationalis Pragae 61 (2), pp. 447-482 : 451-453

Phanaeus tridens Castelnau, 1840

( Figs 1–5 , 32 , 43 , 55 , 63 )

Phanaeus tridens Castelnau, 1840: 81 . Type locality: Mexico, Veracruz, Palma Sola.

Phanaeus frankenbergeri Balthasar, 1939: 245 . Type locality: Mexico. Synonymy established by ARNAUD (1982b: 125) and confirmed here.

Type material examined. Phanaeus tridens: N EOTYPE (suggested, examined from photographs; Fig. 3 ): MEXICO: V ERACRUZ: ♂, Palma Sola (MNHN: MNHN EC10552).

Phanaeus frankenbergeri : HOLOTYPE (examined from photographs; Fig. 4 ): ♂, Mexico (without further locality data) (NMPC: Mus. Nat. Pragae Inv. 26351).

Non-type material examined. MEXICO: V ERACRUZ: 2 ♀♀, Alto Lucero ( GHVM); 2 ♂♂, 700 m NE Apazapan ( IEXA); 2 ♀♀, Conejos ( GHVM); 3 ♂♂ 1 ♀, Cotaxtla ( GHVM); 1 ♂, Laguna Verde ( IEXA); 1 ♀, Motzorongo ( GHVM); 24 ♂♂ 30 ♀♀, Palma Sola ( IEXA: 11 ♂♂ 2 ♀♀; GHVM: 10 ♂♂ 24 ♀♀: VMPM: 3 ♂♂ 4 ♀♀); 1 ♀, Plan de Hayas ( GHVM); 2 ♀♀, Presidio ( GHVM); 1 ♂ 1 ♀ Veracruz ( GHVM: 1 ♀, VMPM: 1♂); 1 ♂ 1 ♀, without specific locality ( GHVM).

Diagnosis. Metallic green, deep green to blue green ( Figs 3–5 ), occasionally with red sheen ( Fig. 4 ). Sides of pronotal disc finely granulate, becoming granulorugose on raised outer margin of disc ( Figs 3–5 , 43 ). Pronotal disc weakly but coarsely rugose ( Figs 3–5 ). Posteromedial process of pronotum produced into denticle, distinctly widened laterally (not reaching anteromedial carina), elongate, and apically bifurcated ( Figs 32 , 43 ). Anteromedial portion of pronotal disc with two denticles, usually joint by medial carina ( Fig. 43 ).Anterolateral margins of disc with distinctly developed ridge of tubercles ( Fig. 43 ). Posterolateral angles of pronotum shorter than posteromedial process of pronotum ( Figs 32 , 43 ). Deep green to green blue elytra, occasionally with red sheen ( Figs 1–5 ). Elytral striae scabriculous, distinctly impressed, superficially punctate ( Figs 1–5 ). Elytral interstriae scabriculous, smooth, superficially punctate, convex ( Figs 1–5 ).

Variability. Minor male. Similar to major males, except for reduction of secondary sexual characters (i.e., cephalic horn, pronotal processes and posterolateral angles). Female. Similar to male, except for head showing trituberculate carina; pronotal sculpture granulate; pronotum with anteromedial black macula, and anteromedial trapezoidal carina, followed by posterior concavity ( Fig. 55 ). This species is variable in colour: typical individuals are green dorsally with blue sheen ( Figs 1, 3–5 , 43 , 55 ), but specimens with metallic red sheen on head and pronotum are occasionally observed ( Fig. 2 ). EDMONDS & ZÍDEK (2012) figured a dark blue female specimen of P. tridens . Nevertheless, none of the specimens revised for this study was dark blue.

Comments. EDMONDS (1994) commented that the type material for many phanaeine species described by Castelnau was probably lost. As discussed by different authors ( EVENHUIS 2012, MALDANER et al. 2017, VAZ-DE-MELLO & CUPELLO 2018), Castelnau’s first personal collection was donated to the today’s Smithsonian Institution ( United States) in 1841, probably including the type series of species names established by CASTELNAU (1840), that of P. tridens among them. Subsequently, this collection was destroyed by a fire in 1865 ( EVENHUIS 2012). Therefore, the original type series was most probably destroyed in that year. Consequently, a neotype deposited at NMVA ( Fig. 5 ) was designated by EDMONDS (1994: 53).

ARNAUD (2001) suggested that the neotype designation by EDMONDS (1994) was inadequate, since the neotype specimen was labeled as coming from Chile ( Fig. 5 ), while P. tridens is endemic to Mexico.Accordingly, ARNAUD (2001) designated a new neotype for P. tridens and commented that his designation would be accompanied by a request to the International Commission on Zoological Nomenclature (ICZN) to set aside EDMONDS’ S (1994) neotype. Our search in the Bulletin of Zoological Nomenclature for Arnaud’s request has been unsuccessful. Indeed, Patrick Arnaud personally confirmed to the first author of this work that he had probably never sent the request to the ICZN. Consequently, the neotype designation by ARNAUD (2001) was not made available and Edmonds’s one was not set aside.

According to the International Code of Zoological Nomenclature, a neotype designation is only available if it fulfils all the conditions under Article 75 ( ICZN 1985). The neotype designation by EDMONDS (1994) is problematic because it does not comply with article 75.d.5 (evidence that the neotype came as nearly as practicable from the original type locality) of the Code. Indeed, the prevailing usage of the name P. tridens is threatened by the identity of EDMONDS’ S (1994) neotype specimen which is correctly identified as P. tridens but mislabelled, indicated to come from Chile ( Fig. 5 ) while this species is endemic to Mexico ( CASTELNAU 1840: Fig. 64 ). In order to clarify the application of the name P. tridens and to conserve its current usage, we suggest to designate a neotype ( Fig. 3 ). In addition, this publication is followed by a request under Article 75.6 to the ICZN (1999) to set aside EDMONDS’ S (1994) neotype ( Fig. 5 ) by its plenary power.

The characters for which P. tridens is differentiated are provided in the diagnosis of this species. The designated neotype is a major male housed at MNHN (MNHN EC10552, Fig. 3 ). The neotype specimen ( Fig. 3 ) fits the original description of P. tridens ( CASTELNAU 1840) : “D’un vert métallique éclatant; devant du chaperon et une longue corne arquée sur la tête noirs; corselet rugueux, profondément excavé dans son milieu, avec deux cornes latérales et une postérieure au milieu; élytres lisses, striées, avec des enfoncemens à la base des quatre premières stries; jambes et tarses noirs. — Mexique ” [translation to English: bright metallic green species; male with a large horn curved over the head; roughened pronotum, deeply excavated medially, with two lateral horns and a posteromedial horn; flattened elytra; impressed fossae at bases of the first four elytral striae; Mexican species)].

Nevertheless, at least four related species ( P. balthasari , Figs 8–9 ; P. daphnis , Figs 10, 12 ; P. herbeus , Figs 16–17 ; and the one to which the name P. tridens is traditionally applied, Figs 1, 3–5 ) fit the original description, being metallic green in colour and from Mexico as mentioned by CASTELNAU (1840). This problem is made worse by the fact that details about the sizes, shapes and positions of the pronotal ornaments are not mentioned by him, which makes it impossible to determine what species Castelnau’s specimen actually belonged to. HAROLD (1863) redescribed P. tridens and suggested Veracruz as the distribution area of this species, while BATES (1887) provided accurate localities from the north-central region of Veracruz. The only one of those four species to occur in north-central Veracruz ( Fig. 64 ) is indeed the one that has been traditionally called P. tridens (or P. tridens tridens ) for more than a century in collections and in literature (e.g. HAROLD 1863, BATES 1887, OLSOUFIEFF 1924, ARNAUD 2002, EDMONDS 1994, EDMONDS & ZÍDEK 2012). Consequently, we believe that designating a specimen from a north-central Veracruz population (such as the Palma Sola one, Fig. 3 ) as the neotype for P. tridens is appropriate and promotes stability.

Distribution. Northern to central Veracruz, Mexico ( Fig. 64 ).

Figures

Figs 1–5. Phanaeus tridens Castelnau, 1840. 1 – male green phase; 2 – male green-red phase; 3 – neotype and labels, present designation (by Christophe Rivier, MNHN); 4 – P. frankenbergeri junior subjective synonymy, holotype and labels (by Jiří Hájek, NMPC); 5 – Eൽආඈඇൽඌ’ (1994) neotype of P. tridens and labels (by Simon Hinkley, NMVA). Scale bar = 1.0 mm.

Figs 32–42. Posterior view of pronotum of major male. 32 – P. tridens Castelnau, 1840; 33 – P. moroni Arnaud, 2001, stat. rev.; 34 – P. bal- thasari Arnaud, 2001, stat. rev.; 35 – P. daphnis Harold, 1863; 36 – P. substriolatus Balthasar, 1939, stat. rev.; 37 – P.herbeus Bates, 1887, stat. rev.; 38 – P.furiosus Bates, 1887; 39 – P.pseudofurcosus Balthasar, 1939, stat. rev.; 40 – P. nimrod Harold, 1863; 41 – P. victoriae Moctezuma sp. nov.; 42 – P. eximius Bates, 1887. Scale bar = 1.0 mm.

Figs 43–54. Lateral view of pronotum of major male. 43 – P. tridens Castelnau, 1840; 44 – P. moroni Arnaud, 2001, stat. rev.; 45 – P. balthasari Arnaud, 2001; 46 – P. daphnis Harold, 1863; 47 – P. coeruleus Bates, 1887, stat. rev. (holotype, by Keita Matsumoto, BMNH); 48 – P. substriolatus Balthasar, 1939, stat. rev.; 49 – P. herbeus Bates, 1887, stat. rev. (green-red phase); 50 – P. furiosus Bates, 1887 (green phase); 51 – P. pseudofurcosus Balthasar, 1939, stat. rev.; 52 – P. nimrod Harold, 1863; 53 – P. victoriae Moctezuma sp. nov. (holotype); 54 – P. eximius Bates, 1887. Scale bar = 1.0 mm.

Figs 55–62. Pronotum of female. 55 – P. tridens Castelnau, 1840; 56 – P. balthasari Arnaud, 2001, stat. rev.; 57 – P. daphnis Harold, 1863; 58 – P. substriolatus Balthasar, 1939, stat. rev. (dark blue-black phase); 59 – P.herbeus Bates, 1887, stat. rev. (green phase); 60 – P. nimrod Harold, 1863 (blue-green phase); 61 – P. furiosus Bates, 1887 (dark blue phase); 62 – P. pseudofurcosus Balthasar, 1939, stat. rev. Scale bar = 1.0 mm.

Fig.63. Phallobase, parameres and endophallite copulatrix of the P.tridens species group. Scale bar = 1.0 mm.

Fig. 64. Predicted distribution of P. tridens Castelnau, 1840, P. moroni Arnaud, 2001 and P. balthasari Arnaud, 2001. The distribution of P. coeruleus Bates, 1887 was not modelled because it is only known from a single locality that needs confirmation.

Figs 8–9.Phanaeus balthasari Arnaud,2001, stat.rev. 8 – male green phase;9 – holotype

Figs 10–12. Phanaeus daphnis Harold, 1863. 10 – male green phase; 11 – male deep blue-green phase; 12 – lectotype and labels (by Christophe Rivier, MNHN). Scale bar = 1.0 mm.

Figs 16–18. Phanaeus herbeus Bates, 1887, stat. rev. 16 – male green phase; 17 – holotype and labels (by Mario Cupello, UFPR); 18 – P. tricornis Olsoufieff, 1924, junior subjective synonymy, redrawn from Oඅඌඈඎൿංൾൿൿ (1924). Scale bar = 1.0 mm.