Polyclada Chevrolat and Procalus Clark are flea beetle genera (Coleoptera, Chrysomelidae, Galerucinae, Alticini). Polyclada is endemic to the Afrotropical region, while Procalus has never been described outside of the Neotropical region. The new combination Procalus maculipennis (Bryant, 1942), comb. nov. is proposed for Polyclada maculipennis Bryant, 1942. Its plausible type locality is Venezuela, and not Cameroon, as recorded on the labels of the type material, and hence the occurrence of P. maculipennis in Africa is questionable.

Afrotropical region, Neotropical region, taxonomy, new combination, lectotype designation

Polyclada Chevrolat, 1836 is an Afrotropical flea beetle genus occurring in sub-Saharan Africa, Saudi Arabia, and Yemen. It comprises 16 described species currently under revision (Biondi and D’Alessandro 2010, 2012; Biondi et al. 2022). The genus is associated with Anacardiaceae (Sclerocarya birrea (A. Rich) Hochst.) and Burseraceae (Commiphora spp.), in a variety of woodland and savannah ecosystems (Chaboo et al. 2007; Iannella et al. 2021). Polyclada is one of the five Afrotropical genera belonging to the Blepharida-group sensu Furth and Lee (2000) and Prathapan and Chaboo (2011), along with Diamphidia Gerstaecker, Xanthophysca Fairmaire, and the recently re-evaluated Blepharidina Bechyné and Calotheca Heyden (Biondi et al. 2017, 2019; D’Alessandro et al. 2018, 2019, 2020, 2021). The Blepharida-group currently comprises 21 genera from the Afrotropical, Nearctic, Neotropical, and Oriental regions (Medvedev 1999; Furth and Lee 2000; Prathapan and Chaboo 2011; Biondi et al. 2017). Furth and Lee (2000) provided a morphological synthesis of the group based on adult characters (tarsal claws, procoxal cavities, head, pronotum, hind femora, eye, proepimeron, and metatibia) and larval characters (antenna, mandible, labrum, stemmata, endocarina, coronal suture, and frontal suture). However, some characters are shared by most (but not all) of the genera (Furth and Lee 2000), and a more comprehensive analysis based on the whole set of genera and representative species is badly needed to more rigorously test the monophyly of the group.

During revisionary studies of the genus Polyclada, we examined the type material of P. maculipennis Bryant, 1942, in the general collection of the Natural History Museum in London (NHMUK) and noticed that it belongs to the Neotropical genus Procalus Clark, 1865. Bryant (1942) based the description of this species on three specimens from Cameroon and believed it to be allied to Polyclada bohemani (Baly, 1861).

Procalus comprises an unknown number of species, but including P. mutans (Blanchard, 1851), P. viridis (Philippi & Philippi, 1864), P. lenzi (Harold, 1876), P. reduplicatus Bechyné, 1951, P. malaisei Bechyné, 1951, and P. silvai Jerez, 1995 (Jerez 1992, 1995). Three more species were reported by Artigas and Solar (2015): P. artigasi Jerez, P. ortizi Jerez, and P. vilosensis Jerez, which are also cited by other authors (Jerez 2003; Prathapan and Chaboo 2011). However, they were described in an unpublished doctoral thesis (Jerez 1999a, cited by Jerez 2003), therefore, according to Article 9.12 of the International Code of Zoological Nomenclature (ICZN 2020), these three names cannot be considered as available.

In this paper, we revise the taxonomic status of Polyclada maculipennis and discuss the possible occurrence of the genus Procalus in sub-Saharan Africa.

Examined material consisted of dried, pinned specimens preserved in the institutions listed below. The specimens were examined and dissected under a Leica M205C stereomicroscope. Photographs were taken using a Leica DMC5400 camera and were compiled using Zerene Stacker v. 1.04. Scanning electron micrographs were taken using a Hitachi TM-1000. Abbreviations of the depositories follow Evenhuis (2022).

Clark (1865) reported the genus Procalus as abundant and widely distributed in Chile, and also present in Brazil and Bolivia. Based on Scherer (1983), this genus occurs in Chile, Bolivia, Brazil, and Argentina. Jerez (1992, 1995) considered Procalus as occurring only in Chile, based on her examined material. Later, she (Jerez 1999b) stated that, based on both public and personal collections, the genus is distributed between latitudes of 30°50'S and 40°50'S, and cited undetermined Procalus material from southern Argentina preserved in the Museum National d’Histoire Naturelle de Paris. Endemic to Chile or not, it has never been described outside of the Neotropical region. What about Procalus maculipennis comb. nov. from Cameroon? We can only speculate about some different hypotheses. Hypothesis A: the genus Procalus has a Gondwanan distribution, even though it is dramatically more abundant in the Neotropical region. The Gondwanan distributions of terrestrial taxa generally refer to genera with clearly differentiated species, or higher taxa (cf. Gómez-Zurita and Cardoso 2021). Among flea beetles, the genera with Afrotropical–Neotropical disjunct distributions occur in the two regions with clearly differentiated species: Terpnochlorus Fairmaire from the Afrotropical region, Venezuela, and Mexico, and, if the synonymy is confirmed, the Malagasy Abrarius Fairmaire, is possibly a senior synonym of Gioia Bechyné from South America (Biondi and D’Alessandro 2012). A second Afrotropical–Neotropical disjunct distribution is observed at a higher taxonomic level; for example, Zomba Bryant is the only representative of the subtribe Monoplatina in the Afrotropical region. This subtribe occurs almost exclusively in the Neotropical and southern part of the Nearctic regions and is present in the Australian region only with the genus Opisthopygme Blackburn, 1896. Based on the diagnostic characters reported by Jerez (1992), Procalus maculipennis comb. nov. is so similar to P. reduplicatus Bechyné that one could evaluate to establish a synonymy in a possible future revision of the genus. For Hypothesis A to be true, these two taxa would have remained so similar despite approximately 135 million years of independent evolution (cf. Donateli Gatti et al. 2021), even though the diversification of Procalus in South America occurred in a much shorter time, likely during the Pliocene (Jerez 1999b). Hypothesis B: the species was imported to Africa via host plants. Procalus species are associated with Lithraea Miers ex Hook. & Arn. and Schinus L. (Anacardiaceae) (Jerez 1992, 1999b). The genus Lithraea, native to South America, is reported as introduced only in California and Tunisia, not in Cameroon or other sub-Saharan countries (POWO 2021). Schinus is also native to South America, is used ornamentally around the world, and was imported into several African countries, but not into Cameroon and adjacent areas (POWO 2021).

Hypothesis C: the types are mislabelled. Starting from the assumption that Leopold Conradt was the collector, it is possible that the entomological material he collected or somehow acquired in Venezuela (where he stayed for some time before 1889) was brought to Cameroon, where he subsequently collected in 1896 (Rohlfien 1975). In fact, material from Venezuela reached the Deutschen Entomologischen Instituts—now Senckenberg Deutsches Entomologisches Institut (SDEI)—via Gustav Kraatz in 1905 along with material from Togo and Cameroon (Rohlfien 1975). It is plausible that the samples from Venezuela were mixed up with, and then erroneously labelled as being from Cameroon. A similar interpretation about the putative and unlikely disjunct distributions of some Hymenoptera species have been offered by Liston et al. (2017). Similarly, Furth (1998) highlighted that Blepharida semisulcata Achard originally described from Cayenne (French Guiana) is a mislabelled specimen from the Afrotropical Region. For us, this is the most plausible hypothesis to explain the alleged presence of Procalus in Africa. However, fieldwork in Cameroon and Venezuela in search of the original habitat and host plants of Procalus maculipennis comb. nov. can put the issue to rest.

We are grateful to the collection managers and curators from the institutions that enabled us to study their material: NHMUK, NHMB, MSNG, and NMPC. Thanks to Dr Josephine Paris (University of L’Aquila) for the English-language editing. We finally thank David Furth, Chi-Feng Lee, an anonymous reviewer, and the editor, Caroline Chaboo, for improving the manuscript.