Monolepta Chevrolat, 1837, the most speciose galerucine taxon: redescription of the type species Monolepta bioculata (Fabricius, 1781) and key to related genera from (Chrysomelidae, Coleoptera)

Monolepta Chevrolat, 1837 is the most speciose galerucine genus, with about 600 described nominal species mainly from tropical and subtropical regions, including 180 species from continental Africa. In the past, the generic delimitation of other taxa based on typological concepts was very inconsistent, and needs to be redefined. To ensure the correct generic placement of species, based on phylogenetic principles, a comprehensive knowledge of the morphology of the type species, Monolepta bioculata (Fabricius, 1781) is necessary, which is presented herein. External and genital characters are figured, and data on distribution and ecology are provided. A phylogenetic analysis of some crucial taxa, and an identification key to all genera of afrotropical galerucines with elongated basi‐metatarsus are provided. Chimporia Laboissière, 1931a ( = syn. nov.) is synonymized with Monolepta. *. 23rd contribution to the taxonomy, phylogeny and biogeography of afrotropical Galerucinae.


Monolepta: mega diversity in Galerucinae
The Galerucinae are one of the most diverse group of the Chrysomelidae (leaf beetles). About 6300 nominal species are currently described, most of them from tropical regions (Wagner 1999a). The genus Monolepta was described in 1837 by Chevrolat. Until now about 600 nominal species have been described, which is more than in any other galerucine genus. Most species have been described from tropical Africa, Asia and Australia, and few also from the southeastern Palaearctic region, and from the Neotropics . All these species have one peculiar, easily recognizable character in common: the strongly Barombiella as a junior synonym of Bonesioides Laboissière, 1925, the type species of which is Ootheca coerulea Allard, 1889. Recent studies of Allard's type material have shown that these species are not congeneric . Species of Barombiella were defined as Monoleptites with an anteriorly strongly narrowed (trapezoidal) prothorax and an extremly narrow and carinate prosternum (Laboissière 1925). A further genus introduced by Laboissière is Chimporia with Chimporia monardi  as type species, which was established for Monoleptites with an exceptionally wide pronotum. Apart from the type species, only one further species, Monolepta ciliata Weise, 1909 was transferred to this genus .
The structure of the procoxal cavities has been used as an important character for the delimitation of galerucine genera in the past. For Monolepta, the procoxal cavities have been described as closed (Chapuis 1875, Weise 1923, while Weise (1892)

previously described
Monolepta as having open coxal cavities. The type species of Barombiella has closed procoxal cavities, but Laboissière (1919) described many of the 42 species described until now in this genus as having ''incompletely closed cavities''. There remain therefore, many inconsistencies in the supraspecific taxonomy of these beetles, and the question arises again: what is Monolepta?
Taxonomic phylogenetic revision of afrotropical Monolepta and related taxa Galerucinae without significant pronotal depressions, the pronotum being nearly rectangular, and the second and third antennomere of the same length, have traditionally been assigned to Monolepta. Most Afrotropical species were described between 1890 and 1950, while between 1965 and 2000 no data on the African species have been published.  was especially aware of the many inconsistent allocations of species to Monolepta. In his Coleopterorum Catalogus on the Galerucinae he commented about the list of ''group not determined'' Monolepta species: ''This group needs revision. Many of these species should be transferred to other genera. Probably some species belong to Candezea. However, most of the species previously placed in Candezea do not''. He was completely correct in this observation, and the taxonomic revision of several taxa has led to many changes (Hasenkamp & Wagner 2000;Middelhauve & Wagner 2001;Wagner , 2001aWagner , 2002Wagner , 2003bWagner , 2005, Schmitz & Wagner 2001Stapel & Wagner 2000Wagner & Scherz 2002;Bolz & Wagner 2004;Steiner & Wagner 2005;Wagner & Kurtscheid 2005). In particular, on the basis of studying the genital structures for the first time, it became necessary to exclude many species originally described in Monolepta from a monophyletic ''core group'' of species including Monolepta bioculata.
In  catalogue, 180 African species are listed, which were originally described in Monolepta. Some of these were earlier transferred to Candezea and Barombiella by preceding authors (Weise 1924;, but the delimitation of these genera was inconsistent. In their earlier works, Weise and Bryant used Candezea only as a subgenus of Monolepta (Weise 1924;Bryant 1938), andBryant (1953) did not accept the previous ''generic concept'' of Barombiella. During the recent revision of Afrotropical Monolepta, about 90 species had to be transferred to other genera and about 40 names were found to be synonyms. In addition to the 50 remaining valid species, about 50 species have been newly described (Wagner , 2001a(Wagner , 2001b(Wagner , 2002(Wagner , 2003b(Wagner , 2005 or await description.

Methods
Morphometric measurements were made for external characters. Absolute measurements are: total length from the clypeus to apex of the elytron, length of elytron, maximal width of both elytra (usually in the middle or posterior third of the elytra), and width of pronotum. Relative measurements are: length to width of pronotum, maximal width of both elytra to length of elytron, length of the second to third antennomeres, and length of third to fourth antennomere. Fifteen specimens were measured: minimum, maximum values and means are given. Figures include illustrations of the colour pattern (dorsal view), with right antenna. Genital structures are given in detail, including an overview of male and female genitalia and details. The redescription of Monolepta bioculata is based on 369 specimens from the following collections. Acronyms used, responsible persons and number of specimens in brackets: Bishop Museum, Honolulu (BPBM; A. Samuelson; n54); Natural antennomere 0.83-1.00 (0: 0.93), length of third to fourth antennomere 0.36-0.46 (0: 0.42). Antennomeres 1-3 yellowish-red to red (Figure 8a), sometimes also proximal half of fourth antennomere red (Figure 8b), other antennomeres dark brown to black (Figure 8).

Diagnosis
Monolepta bioculata can be easily distinguished from all other Monolepta species by its peculiar colour pattern of two ovate eye-like, yellow, black margined spots on each elytron. It could be confused with two other species: M. zambesiana Jacoby, 1906 occurring sympatrically with M. bioculata in northern South Africa. This species also has yellow, black margined elytral spots, but those are elongated or stripe-like. Furthermore, this species has  Figure 10). (14)  no black apical antennomeres, a more elongated third antennomere (length of second to third antennomere: 0.75-0.81; M. bioculata: 0.83-1.00), and a much narrower pronotum (pronotal length to width: 0.58-0.63; M. bioculata: 0.51-0.55). Monolepta laboissierei Wagner, 2001b is also similar, but allopatrically distributed in relation to M. bioculata, being known from northern Democratic Republic of Congo to Zambia. It also has two ovate, black margined spots on each elytron, but those spots are smaller and the margins broader than in M. bioculata, and it can be also distinguished by its very slender median lobe and the shape of the bursa sclerites. All the other approximately 100 known valid species of afrotropical Monolepta have very differently coloured elytra. They can be uniformly yellow, red or black, sometimes with the apex of a different colour, or the elytra can bear black or red transverse bands or a black suture, margins and a median transverse band forming a cross-like pattern.

Distribution
Only known from some parts of the Republic of South Africa, particularly abundant in the Cape Provinces (Figure 20). Ecology Some specimens were collected when feeding on, sometimes ''damaging'', lemon leaves (Citrus spec., Rutaceae), in one case feeding on buds and flowers of Rumex angiocarpus (Polygonaceae), bud and flowers of Cyclopia maculata (Fabaceae), and flowers of Sporobolus pyramidalis (Poaceae) was recorded, a few others were collected on flowers without detailed plant identification.
Chrysomela quadrimaculata Goldfuß, 1805 A type specimen is not avaiable, but a colour illustration is provided in the original description which clearly indicates the species' identity.

Phylogenetic considerations
Following the completion of the taxonomic revision of several groups of afrotropical galerucines, first studies on their phylogenetic relationships have been carried out based on morphological characters (Wagner 2004). Fourty-four species analysed with 14 genitalic characters and 20 characters based on external morphology are included in the analysis, using maximum parsimony (for details of character coding and matrix see Wagner 2004). About 10% of the valid afrotropical species of Monolepta and Bonesioides and about 50% of Candezea, Afrocrania, and Afromaculepta species have been included with species of other genera originally placed in ''Monoleptites''. Furthermore, some short-legged Galerucinae, Exosoma lusitanicum (Linnaeus), Exosoma politum (Jacoby) and Oides humeralis Gahan, the latter as the outgroup, have been included. Results are presented as a strict consensus tree ( Figure 21).
The traditional delimitation of Monolepta, Candezea and Barombiella has resulted in polyphyletic groups. Also ''Monoleptites'' is polyphyletic, since an elongated metatarsus has evolved more than once in the Galerucinae. Genitalic characters, in particular, reveal a much better generic delimitation. The monophyly of Monolepta s. str. is based on two synapomorphies, two pairs of strongly sclerotized bursa sclerites, and the presence of three distinct types of endophallic spiculae. Other important diagnostic genitalic characters are the large and spherical spermathecal nodulus, the short tectum of the median lobe, and the second and third antennomeres of approximately the same length. At least one external character, the relative length of the second and third antennomere, might be apomorphic for Monolepta, but until the revision is completed, this statement is preliminary. However, this character has a high diagnostic value. All taxa with significantly elongated third antennomeres (length of second to third antennomere: 0.45-0.80) need to be transferred to other genera, in particular all taxa with partly or entirely metallic dorsal colour (see identification key below).
The genus Chimporia was established for those ''Monoleptites'' having an exceptionally wide pronotum. However, despite this conspicious character, the genitalic structures clearly reveal affiliation to Monolepta.
The number of Afrotropical species of Candezea was reduced from 39 to only eight valid species (Wagner & Kurtscheid 2005). In the cladogram the four species involved in the analysis cluster as a paraphyletic group together with Afrocandezea and Afrocrania as a terminal taxon (Figure 21). These taxa are in particular characterized by an apically incised tectum of the median lobe, and the form of the endophallic armature. However, the phylogenetic position of Candezea cannot be fully resolved with the available data. The analyses of these groups need to be pursued with an extended set of characters when the taxonomic revision of all Afrocrania and Afrocandezea species is completed.
''Clade 1'' comprises a well-supported group of species originally described in Monolepta and Candezea, which are phylogenetically very remote from the type species of those genera. This clade is characterised by several autapomorphies (see Wagner 2004) and the species will be redefined under a new genus name in the near future (Wagner in prep.). The character pattern is most similar to Dyolania antennalis, the type of Dyolania Laboissière 1931b, a genus which was synonymized with Luperodes Motschulsky, 1858 by , but is not congeneric and need to be re-established. A revision on this group is in preparation.
As well as recently described species, Afromaculepta includes additional taxa originally described in Monolepta. The introduction of this new genus (Hasenkamp & Wagner 2000) as a monophyletic group is well justified by several apomorphies, indicated by a high Bremer support index. Some of the apomorphic characters also have a high diagnostic value, such as the yellow and black elytra having small, symmetrically arranged spots, and the peculiar type of endophallic spiculae which bear rows of spines.
Bonesioides is not closely related to any other taxon named above. Species of this genus have a very different external appearance, metallic blue or metallic green head and thorax, and most species with metallic dorsum originally placed in Monolepta have been recently transferred to this genus . Species of this group show a wide variation in the form of the basi-metatarsus.
A further group, which is not yet named (''clade 2''), includes taxa with short-and longlegged Galerucinae. This clade comprises typical species of Galerudolphia, which has been revised recently (Bolz & Wagner 2005). One important external character of ''clade 2'' is the trapezoidal pronotum, which is typical for Barombiella. After revision, this genus turned out as monotypic, and since Barombiella violacea with its overall metallic colouration is closely related to Bonesioides, the non-metallic coloured species of Barombiella and several species formerly described in Monolepta which are also characerised by a strongly trapezoidal pronotum need to be excluded from these taxa.

Identification key for Afrotropical Galerucinae with elongated basi-metatarsus
The following key can be used for all recently revised or newly described genera of afrotropical Galerucinae with an elongate basi-metatarsus, including some species of Bonesioides and Galerudolphia, which have short basi-metatarsi. Since the revision of all species is not yet completed this key is provisional. Checking of genital characters of both sexes is usually necessary. Specimens having genitalia which do not fit to the structures mentioned below should be excluded. 7. Small, 2.4-4.9 mm, pronotum broad at base, trapezoidal, elytra usually slender (width of both elytra together to length of elytron 0.39-0.75), uniformly yellow, with or without black suture and margins, never with transverse black bands, legs short (length of basi-metatarsus to metatibia 0.34-0.50); median lobe without endophallic spiculae, deeply incised at apex . . . Galerudolphia (15 species) -Total length 4.2-8.1 mm, pronotum rectangular or significantly narrowed in the basal third (heart-like), elytra usually broader (width of both elytra to length of elytron: 0.57-0.75), legs usually much longer (length of basi-metatarsus to metatibia more than 0.50); median lobe with endophallic spiculae, apex of median lobe not incised .