Pachycnema (Macacoplia) Cupello & Ribeiro-Costa, 2019

Cupello, Mario & Ribeiro-Costa, Cibele Stramare, 2019, Nomenclatural clarification on some Southern African monkey beetle genera (Scarabaeidae: Hopliini: Pachycnemina), Zootaxa 4543 (1), pp. 137-144 : 138-140

Pachycnema (Macacoplia) Cupello & Ribeiro-Costa , new subgenus

Etymology. The new genus-group name is a compound word composed of one of the New Latin words for monkey, “ macaca ” ( Brown 1956), which makes reference to the English vernacular name “monkey beetles” by which the Hopliini are widely known, and the name of the type genus of the tribe, Hoplia Illiger, 1803 . Illiger (1803: 228) remarked his new nominal genus derived from the Greek word oπλη, meaning hoof or unsplit claw, which certainly refers to the fact that the Hopliini , differently from most of the other scarabs, possess a single enlarged claw on each metatarsus instead of two smaller claws (a character that has been hampering a clear positioning for the group among the scarab subfamilies; see the discussion on this subject by Lacroix [1997], Carrillo-Ruiz & Morón [2006], and Ahrens et al. [2011]). The gender is feminine.

Type species. Pachycnema moerens Péringuey, 1902 , here designated.

Differential diagnosis among the subgenera of Pachycnema . Head and clypeus black, with bristles or hairs. Clypeus trapezoidal, anterior edges reflexed, forming two teeth. Anterior margin of pronotum concave, anterior edges acute, lateral margins S-shaped, posterior edges obtuse, posterior margin regularly rounded. Pronotum with or without pattern, covered with hairs, bristles and/or scales. Scutellum longer than broad, setose and/or squamose or bare. Elytra attenuate apically, rounded separately at apex, with distinct humeri and apical declivities joined by a costa; bare or covered with scales and/or bristles sometimes forming a pattern. Abdomen densely squamose. Protibia tridentate, with spur. Metatibia with spur, thickened calf-shaped. Metatarsus non-coalescent. Sexual dimorphism slightly developed. Metatibia normal in females. [Diagnosis extracted from Dombrow (1998b: 67). Readers are referred to that work for more details on the morphology of Macacoplia new subgenus and its species and arguments for its placement among the subgenera of Pachycnema ].

Species composition. 12 species, namely Pachycnema (Macacoplia) abdominalis ( Burmeister, 1844) ; P. (M.) albosquamosa Dombrow, 1998; P. (M.) ferruginea Dombrow, 1998; P. (M.) kochi Schein, 1959 ; P. (M.) lineola Burmeister, 1844; P. (M.) marginella (Fabricius, 1792); P. (M.) moerens Péringuey, 1902 ; P. (M.) namaqua Péringuey, 1902; P. (M.) rostrata Burmeister, 1844; P. (M.) saga Péringuey, 1902; P. (M.) schoenherri Dombrow, 1998; P. (M.) tibialis ( Olivier, 1789) . Species composition following the ones included in Pachycnemula by Dombrow (1998b).

Geographical distribution. Largely endemic to southwestern South Africa, being present in the provinces of Northern, Western, and Eastern Cape. A single species ( P. kochi ) was also recorded from southern Namibia ( Dombrow 1998b).

Remarks. As discussed before, Dombrow (1998b) considered Melolontha tibialis Olivier, 1789 the type species of the subgenus named by him as “ Pachycnemula ”. Therefore, in order to keep with his interpretation of that taxon as close as possible, initially we intended to designate M. tibialis as the type species of Macacoplia new subgenus. Nonetheless, since the type series of that nominal species is considered to be lost ( Dombrow 1998b: 73), we believe it would be too risky to fix our new nominal genus to M. tibialis . Not even Olivier’s (1789) illustration of that species gives us enough confidence that the generic identity of this species will not be questioned by future revisers of the group. Therefore, we decided not to designate M. tibialis as the type species of Macacoplia new subgenus. Instead, still aiming at maintaining the nomenclature as close as possible to Dombrow’s interpretation, we choose to fix the new nominal genus to the species most closely related to P. tibialis , Pachycnema moerens Péringuey, 1902 . The lectotype male of P. moerens was designated by Dombrow (1998b: 70) from Péringuey’s two syntypes and is housed at the Iziko South African Museum, in Cape Town, South Africa.

A further issue concerning the nomenclature of Pachycnema refers to the alleged ( Dombrow 1998b: 42) synonymy between this name and Pachycnemida Péringuey, 1902 . In his description of the then-genus Pachycnemida, Péringuey (1902: 689) included just one species in it, Pachycnema signatipennis ( Burmeister, 1844) , which is therefore the type species of Pachycnemida by original monotypy (Code’s Article 68.3). In Schein’s (1959a) five-subgenus classification of Pachycnema , Pachycnemida continued to be monotypic. Dombrow (1998b), however, after examining the pertinent type specimens, synonymized P. signatipennis with P. multiguttata (Thunberg, 1818) , placing the species in the subgenus Physocnema Burmeister, 1844 . Therefore, since the type species of Pachycnemida (albeit as a junior synonym) is included in Physocnema , not in Pachycnema s. str., Pachycnemida is a junior synonym of Physocnema , not of Pachycnema as erroneously stated by Dombrow (1998b: 42).

Finally, a word must be said on the objective synonymy between Pachycnema Le Peletier de Saint-Fargeau & Audinet-Serville, 1828 and Pachypus Billberg, 1820 , which could potentially threaten the current validity of the former nominal genus. Pachypus Billberg, 1820 was made available in Billberg’s (1820) list of his arthropod collection; although no description was given for the new genus, the inclusion of an already-available nominal species in Pachypus (namely, Melolontha crassipes Fabricius, 1775 ) granted its availability, and that nominal species is the type species of Pachypus by original monotypy. The publication of this new name, however, went unnoticed to most entomologists and eventually Le Peletier de Saint-Fargeau & Audinet-Serville (1828) established Pachycnema to name essentially the same genus taxon, and their name has been used ever since. Silfverbeg (1984) was the first author to rediscover Billberg’s name, but he noted that since this name was a senior homonym of Pachypus Dejean, 1821 , a nominal genus commonly used to denote a group of melolonthine species ( Melolonthinae : Pachypodini ), the suppression of Billberg’s name could be proved advantageous. This was eventually formally proposed by Bouchard et al. (2011), who applied Code’s Article 29.9.2 and considered Billberg’s Pachypus a nomen oblitum, while Dejean’s Pachypus is a nomen protectum and, therefore, has priority in the homonymy. Since Pachypus Billberg is permanently invalid, its older junior synonym (viz., Pachycnema ) should be used as a substitutive name. Therefore, the current use of Pachycnema as a valid name should be maintained.

The current understanding of the taxonomy and nomenclature of Pachycnema and its subgenera can thus be summarized as follows:

Genus Pachycnema Le Peletier de Saint-Fargeau & Audinet-Serville, 1828

Subgenus Pachycnema s. str. Type species: Melolontha crassipes Fabricius, 1775 , by subsequent designation of Schein (1959a: 84).

= Pachypus Billberg, 1820 (non Dejean, 1821), nomen oblitum ( Bouchard et al. 2011). Type species: Melolontha crassipes Fabricius, 1775 , by original monotypy ( Billberg 1820: 4).

= Pachycnemula Schein, 1959 . Type species: Melolontha crassipes Fabricius, 1775 , by original designation ( Schein 1959a: 92).

Subgenus Stenocnema Burmeister, 1844 . Type species: Stenocnema pudibunda Burmeister, 1844 , by original monotypy ( Burmeister 1844: 67).

Subgenus Physocnema Burmeister, 1844 . Type species: Pachycnema calcarata Burmeister, 1844 , by subsequent designation of Schein (1959a: 88) (not Pachycnema flavolineata Burmeister, 1844 as claimed by Dombrow [1998b: 45]).

= Pachycnemida Péringuey, 1902 . Type species: Pachycnema signatipennis Burmeister, 1844 , by original monotypy ( Péringuey 1902: 689).

Subgenus Macacoplia Cupello & Ribeiro-Costa , new subgenus. Type species: Pachycnema moerens Péringuey, 1902 , here designated.