Taxonomic revision of the genus Machleida Fåhraeus, 1870 (Tenebrionidae, Pimeliinae, Asidini)

Abstract The taxonomic concept of the genus Machleida Fåhraeus, 1870 is tested and revised based on newly identified material. The following new species are described: Machleida banachi, M. flagstaffensis, M. tarskii, and M. zofiae Kamiński. Machleida capillosa Wilke, 1925 is considered as a junior subjective synonym of Asida devia Péringuey, 1899. Asida lecta Péringuey, 1899 (= Pseudomachla recurva Wilke, 1925) (transferred to Afrasida), Machleida nossibiana Fairmaire, 1897 (transferred to Scotinesthes), and Machleida tuberosa Wilke, 1925 (interpreted as incertae sedis in Asidini) are excluded from Machleida. An identification key for the species of the newly revised Machleida is provided. The present paper brings the total number of species within the genus to six (M. banachisp. nov.; M. devia (Péringuey, 1899); M. flagstaffensissp. nov.; M. nodulosa Fåhraeus, 1870; M. tarskiisp. nov.; M. zofiae Kamiński sp. nov.). The morphology of female terminalia (ovipositor and genital tubes) is described for the genus for the first time.

According to the most recent hypothesis, this genus can be distinguished from the other Asidini by the following combination of characters (Koch 1962): pronotum strongly cordiform, often with subangular sides; pronotal base as broad as the elytral base (except for M. nossibiana with narrowed pronotal base); pronotal disc with large primary sculpturing consisting at least of two median carinae on the basal half of the middle section; hypomeron with shallow, posteriorly-abbreviated antennal sulcus; elytra with large tubercles; sides of the elytral surface limited by the apically abbreviate costa; epipleuron ventral in position (not visible from above); underside of the basal segment of the protarsi simple, non-tomentose; basal segment of posterior tarsi not elongated; and outer margin of anterior tibiae inermous.
As a result of the recent efforts aimed at revising South African Asidini many previously unstudied specimens of Machleida were gathered. This, together with an examination of existing type material, enabled a detailed revaluation of the taxonomic status of this genus and its species components.

Material and methods
This study was based on material from the Museum für Naturkunde der Humboldt Universität, Berlin, Germany (referred as Berlin Mus.); Natural History Museum, London, United Kingdom (British Mus.); Muséum national d'Histoire naturelle, Paris, France (Paris Mus.); Hungarian Natural History Museum, Budapest, Hungary (Budapest Mus.); and Ditsong National Museum of Natural History, Pretoria, South Africa (Transvaal Mus.). The original label data for the specimens is given in quotation marks and separated by a comma. Each line of the original label data is separated by a forward slash.
Morphological terminology mostly follows that of Doyen (1994) and Smith (2013), with additional specialized terms used for the male and female terminalia (Tschinkel and Doyen 1980;Pérez Vera 2014;Giraldo-Mendoza and Flores 2019). Terminalia were investigated using standard methodologies (see Iwan and Kamiński 2016). Morphological measurements were recorded with a filar micrometer. Length was measured along the midline from the anterior margin of the clypeus to the apex of the elytra. Width was measured across the widest points.
The phylogenetic species concept of Wheeler and Platnick (2000) is employed, as in several recent taxonomic works (Smith et al. 2011;Smith 2013;Smith and Wirth 2016). This species concept is appropriate due to its emphasis on character transformations between species and the lack of available data beyond adult morphology and distribution for any of the species in the genus.
Images were taken using a Canon 1000D body with accordion bellows and a Canon EF 100 mm macro lens. Drawings were prepared in Photoshop CS5 using photographs as templates. The distribution of species was illustrated using Quantum GIS (QGIS) v. 2.4, while the vector layers were downloaded from the Natural Earth web-page (http://www.naturalearthdata.com). The division of the Afrotropical Realm into ecoregions follows Olson et al. (2001). The list of all investigated localities is presented in Appendix 1.  Wilke, 1925 (see below) from Machleida increased the morphological consistency of the genus. As a result, some of the previously listed diagnostic characters needed to be revised (e.g., sculpture of pronotum). Additionally, the present investigation reveals that some of the characters proposed by Koch (1962) are too variable within Afrotropical Asidini to be sustained as diagnostic for Machleida. A revised diagnosis is presented below.

Genus
The representatives of this genus can be distinguished from other Afrotropical Asidini by the following combination of characters: antenna appearing as 10-segmented, with antennomeres 10 and 11 of equal in width (Fig. 1D); mentum reduced basally, not fully filling buccal cavity (Fig. 1C); pronotal disc with large primary sculpturing consisting of two median carinae merged in the middle (Fig. 1B), carinae not merging in M. zofiae Kamiński sp. nov. (Fig. 1A); hypomeron with shallow, posteriorly abbreviated antennal sulcus; elytra with large tubercles (Fig. 2); and expanded epipleura (sometimes fully fused with the neighbouring part of elytra) (Fig. 3A, B). Moreover, all Machleida species shares a peculiar structure of mesoprescutum, i.e. base deeply emarginate (Fig. 3C).
Because of its Malagasy distribution, the taxonomic placement of M. nossibiana Fairmaire, 1897 within the South African Machleida was previously questioned by several authors (Chatanay 1914;Wilke 1925;Gebien 1937). However, based on a single non-typical specimen, Koch (1962) tried to provide some morphological support for this taxonomic hypothesis. According to his view M. nossibiana generally resembles species of Machleida and can be separated from other Malagasy Asidini by the non-soleate underside of the tarsi. In his diagnosis he compared this species to M. nodulosa and highlighted two main morphological differences: antennae robust in M. nossibiana, slender in M. nodulosa; and prosternal process broad in M. nossibiana, narrow in M. nodulosa. The current reinvestigation of the type material of M. nossibiana (Appendix 2: Fig. S1B) revealed a high morphological resemblance of this species to representatives of the genus Scotinesthes Fairmaire, 1895 (Koch 1962). Namely, the aforementioned characters used by Koch to separate M. nossibiana from M. nodulosa are characteristic for Scotinesthes. Moreover, M. nossibiana shares a common structure of the mentum (fully filling buccal cavity; reduced basally in Machleida) with the other species representing that Malagasy genus. As a result, nossibiana is transferred from Machleida and the following new combination is introduced: Scotinesthes nossibianus (Fairmaire, 1897) comb. nov.
Reinvestigation of the type material revealed that Machleida tuberosa Wilke, 1925 has a peculiar pronotal sculpturing, i.e., disc without carinae but densely covered with small setose tubercles (Appendix 2: Fig. S1C). The second character seems to be unique for this species among the other southern African Asidini. Because of the aforementioned features, M. tuberosa does not fit the newly proposed taxonomic concept of Machleida and is hereby excluded from this genus. The exact placement of this species (possibly a new genus) requires further investigation in a wider taxonomic context. At the moment tuberosa is treated as incertae sedis Asidini.
Distribution. Representatives of this genus have been collected in the following ecoregions of South Africa ( Elytral tubercles distributed evenly, not forming ridges (Fig. 2D). Elytra densely covered with noticeable punctures (Fig. 3E) .... Machleida nodulosa -Elytral tubercles absent or sparse in middle of disc, laterally forming at least two lateral ridges (Fig. 2E). Elytra impunctate or with extremely sparse punctures ...5 5 Elytral disc only basally with pair of oblong tubercles (middle part of elytra without tubercles). Elytral humerus dentate, protruding laterad ( Fig. 2A). Elytral slope gradually falling towards apex of elytra (Fig. 3B)  Notes. During the preparation phase for this study the holotype of Asida devia was not found in any of the queried collections, i.e. Iziko Museum of South Africa in Cape Town and the institutions listed in the Material and methods section. However, the original description indicates several unique morphological features of this species (i.e. large body size, presence of densely distributed microtubercles on the elytral disc), which were used to differentiate it from other congeners.
Distribution. Representatives of this species have been collected in the following ecoregions of South Africa (Fig. 5) Notes. The last researcher to study the types of Machleida nodulosa and Asida legitima was Péringuey (1904). This fact indicates that those specimens should be preserved in the Iziko Museum of South Africa (Cape Town). However, the types of those both synonymous species were not found in any of the queried collections, i.e. Iziko Museum of South Africa in Cape Town and the institutions listed in the Material and methods section.
Descriptions of M. nodulosa and A. legitima indicate several specific morphological features (i.e. relatively small body size; presence of dense punctures on elytra; elytral tubercles distributed evenly, not forming ridges), which were used to differentiate them from other congeners.

Machleida banachi
Diagnosis. This species can be distinguished from all its congeners by the unique structure of elytra: disc medially lacking tubercles and dentate humerus (strongly protruding laterad) ( Fig. 2A). This species most closely resembles Machleida tarski (see identification key above).
Etymology. This newly introduced name honours Stefan Banach (30 March 1892-31 August 1945), prominent Polish mathematician and founder of modern functional analysis. He was educated at the Technical University of Lwów and was a founder of the Lwów School of Mathematics.
Distribution. Representatives of this species have been collected in the following ecoregions of South Africa (Fig. 5) Diagnosis. On account of a large body size this species is similar to Machleida devia. Both species can be separated by the characters listed in the identification key provided above.
Etymology. The species epithet refers to Flagstaff (Eastern Cape, South Africa), a town near the collecting localities of this new species.
Distribution. Representatives of this species have been collected in the following ecoregions of South Africa ( Diagnosis. This species most closely resembles Machleida banachi, as both share a similar body size, structure of pronotal disc (median carinae merging) and elytra (tubercles forming two lateral ridges). They can be separated by different formation of the elytral slope (extremely steep in tarskii; gradually falling in banachi) (Fig. 3A, B). For other characters separating those both species see the identification key.
Etymology. The species epithet is in honor of Alfred Tarski (14 January 1901-26 October 1983), Polish-American logician and mathematician. Educated at the University of Warsaw and a member of the Lwów-Warsaw school of logic, he immigrated in 1939 to the USA, where he became a citizen in 1945. Alfred Tarski carried out research in mathematics at the University of California, Berkeley, from 1942 until his death in 1983.
Distribution. Representatives of this species have been collected in the following ecoregion of South Africa (Fig. 5) Diagnosis. Easily distinguishable from other congeners by the specific structure of pronotum: disc with median carinae interrupted in the middle of pronotal disc (Fig. 1A); lateral tubercles situated below the half pronotal length (Fig. 1A). This is also the only Machleida species with relatively large tuberculate horns on frons. Superficially this species can be confused with M. flagstaffensis. However, besides the characters listed above those two species can be distinguished by different structure of elytral slope, i.e. steep in flagstaffensis (falling at angle of 75°) versus gradually falling in zofiae (at angle of 50°).
Distribution. The holotype of this species was collected in the following ecoregion of South Africa (Fig. 5): KwaZulu-Cape coastal forest mosaic.