Review of Mausoleopsis amabilis (Schaum, 1844) (Scarabaeidae, Cetoniinae), with Description of a New Species and a New Subspecies †

: The extremely variable and widespread cetoniine species Mausoleopsis amabilis (Schaum, 1844) is reviewed here using analyses of over 1500 specimens and observations across its entire distribution range. As a result, M. a. heterospila (Gerstaecker, 1867) is reinstated as a valid subspecies and a new subspecies, M. a. interrupta ssp. nov., is also erected, in order to account for the geographically distinct populations occurring across East Africa and the eastern lowlands of southern Africa, respectively. Mausoleopsis a. ruteri Antoine, 1989 is conﬁrmed as a valid subspecies for the West African populations, while M. lerui Antoine, 2004 is synonymised with M. a. heterospila , as it appears to represent an extreme variation of that subspecies. On the other hand, a new species, M. gariepena sp. nov., is described from the Gariep Desert and surrounding arid areas of South Africa and Namibia and compared to its sister species, M. amabilis s. l. The new species appears to be an arid habitat specialist, adapted to survive in the driest part of the subcontinent.


Introduction
The subfamily Cetoniinae, popularly known as fruit and/or flower chafers, is a rather diverse scarab grouping which currently consists of 12 tribes subdivided into 46 subtribes [1]. The tribe Cetoniini is particularly well-represented in the Afrotropical Region, with the subtribes Cetoniina and Leucocelina comprising some 60 genera and over 550 species [2]. With the re-demotion of Elassochiton to the rank of subgenus [3], the Leucocelina genus Mausoleopsis now includes two rather diverse subgenera, together including 21 species and three subspecies [2]. Within Mausoleopsis s. s., M. amabilis is undoubtedly the most widespread and variable species across the African continent and adjacent islands. Originally described by Schaum [4] from material collected by M. Melly in the Algoa Bay area (ZAF, EC), the species was subsequently reported from the then Natal (now ZN) and Mozambique colonial territories and eventually even in East Africa, leading to Gestaecker [5] being the first to comment on its remarkable variability, particularly as recorded in its dorsal white ornamentation.
Mausoleopsis amabilis s. l. actually exhibits an extraordinary range of patterns in its maculation, which has caused confusion and controversy throughout the literature of its description and revision (cf. [6] and references therein). Gerstaecker [5] first proposed the name heterospila for its population from East Africa, using descriptions of specimens from Mombasa (KEN) and Zanzibar (TAN). Much later, Antoine [7] proposed the name ruteri for the West African populations, using material from Cote d'Ivoire, Angola, Burkina The background colour in this new species is reddish-brown to dark brown, rather than shiny black as is typical in Mausoleopsis amabilis s. l. The white cretaceous spots on its pronotal and elytral discs are consistently present and generally well-developed ( Figure 1A,C), although the two pairs on the side of the scutellar apex and above the elytral apical maculae, respectively, are normally very small and even absent in some specimens. Both pronotal bands and elytral maculae are generally creamy in colour, rather than pure white as in most M. amabilis s. l. cases. Furthermore, the clypeus of M. gariepena sp. nov. is more densely sculptured and with a thicker anterior margin than in M. amabilis s. l. The posterior margin of the elytron is smoothly rounded in M. gariepena and exhibits an apical spine that is far less protruding than in M. amabilis s. l. Its mesosternal lobe exhibits a broader base and smaller and sparser punctures than in M. amabilis s. l. ( Figure 2C). Finally, in the new species, the apical portion of the dorsal lobes of the aedeagal parameres are wider but shorter and bent downwards at right angles, rather than further towards the Diversity 2022, 14, 248 4 of 27 base as in M. amabilis s. l. The apical spines on its dorsal lobes are also much shorter than in M. amabilis s. l. (Figure 2D-F).
Diversity 2022, 14,x FOR PEER REVIEW 4 of 27 base and smaller and sparser punctures than in M. amabilis s. l. ( Figure 2C). Finally, in the new species, the apical portion of the dorsal lobes of the aedeagal parameres are wider but shorter and bent downwards at right angles, rather than further towards the base as in M. amabilis s. l. The apical spines on its dorsal lobes are also much shorter than in M. amabilis s. l. (Figure 2D-F).

Description of Holotype Male
Size: Total length = 14.4 mm; maximum width = 7.9 mm. Body: Dark brown, shiny and dorsally glabrous, with creamy-coloured cretaceous bands, maculae, and spots distributed across pronotal and elytral surfaces as well as on metacoxal dorsal ridge; with dense and fine round sculpture on head, becoming scattered on pronotum and large and predominantly horseshoe to geminate-shaped along elytral striae (Figures 1A-C and 2A).

Description of Holotype Male
Size: Total length = 14.4 mm; maximum width = 7.9 mm. Body: Dark brown, shiny and dorsally glabrous, with creamy-coloured cretaceous bands, maculae, and spots distributed across pronotal and elytral surfaces as well as on metacoxal dorsal ridge; with dense and fine round sculpture on head, becoming scattered on pronotum and large and predominantly horseshoe to geminate-shaped along elytral striae .
Head: Dark brown to black, with deep concavity between frons and apex; clypeus with lateral and anterior margins steeply upturned, mildly sinuate at apex and with anterolateral corners smoothly rounded; surface entirely glabrous, but covered in round, dense and regularly spaced round sculpture, becoming rugulose along margins; antenna dark brown, with club approximately as long as flagellum and pedicel combined; few thin tawny setae scattered across flagellum, but lacking completely on pedicel (Figure 2A).
Pronotum: Brown, shiny, and completely glabrous, with wide creamy band on each lateral margin uninterrupted but not reaching basal margin; pair of creamy circular spots on the disc in suprascutellar position and near base; irregularly octagonal, widening at base, with angles smoothly rounded and small tubercle in central apical area; basal margin evenly convex, with mild sinuation above scutellum and shallow depression between pair of creamy spots; small and shallow round punctures regularly spaced across entire surface, becoming larger on declivities but not visible in areas covered by cretaceous bands ( Figure 1A,C).
Scutellum: Dark brown, shiny, and glabrous, with scattered but large oval to crescent sculpture in basal fourth; broadly isoscelic triangular in shape, elongate with concave lateral margins and extremely pointed at apex; lateral grooves well-defined and deep across entire length, widening progressively towards base ( Figure 1A).
Elytron: Brown, shiny and glabrous, with two large creamy maculae on lateral margin, one on apical margin and four spots on disc forming symmetric pairs with opposite elytron and distributed as follows: (1) basal near scutellar apex, (2) median near first macula, (3) median near suture, (4) apical above macula; costae obsolete to weakly elevated and barely visible but humeral callus prominent and protruding outwards as widest area, leading also to extreme concavity in subhumeral arch; striae marked with lines of large horseshoe punctures, becoming geminate on medio-apical portion of disc; posterior margin smoothly rounded and apico-sutural margin sharply upturned, forming acute spinal projection at apex (Figures 1A,C and 2B).
Pygidium: Dark brown to black, with pair of symmetric creamy maculae on each side not reaching apical margin; quadrilateral in shape, with bulging dome at centre and steep declivity on apical margin; with dense network of shallow and subconcentric rugulose sculpture across entire surface and short light-yellow to tawny setae scattered around apical declivity, becoming longer and finer along lateral margins and apex ( Figure 2B).
Legs: Dark brown and shiny with occasional black tips or edges; tarsi of average cetoniine length and longer than tibiae, with basal segment of meso-and metatarsi much shorter than other segments; protarsal claws unequal, with inner claw approximately twice as long and thick as outer one; tibiae irregularly sculptured and covered in short and regularly spaced light-yellow setae, becoming longer and finer on inner margins; protibia narrow and bidentate, with both denticles curving outwards and apical denticle approximately twice as long as second; meso-and metatibia with supra-apical tranverse carina on outer margin and apical margin bluntly tridentate; spurs on both legs equal and poorly produced; metatibia and metafemur hypertrophic, with convex carina on inner margin and marked curvature, respectively ( Figure 1A-C).
Ventral surface: Dark brown to black and shiny, with large creamy macula on metasternum reaching margin of meso-metasternal process; lesser macula also present on metacoxa and minor spots on metepisternum and on marginal end of abdominal sternites 1-5; covered in light-yellow to tawny setae emerging at centre of round to horseshoe punctures, except on femoral bases and central areas of abdominal sternites 6-7; setae short to medium sized and scattered on abdominal sternites, ventral femoral surfaces, metasternum and mesometasternal process, becoming denser and longer around mesosternal lobe, on inner femoral margins and on prosternum; mesosternal lobe crescent-shaped, very narrow but laterally oblong and smoothly rounded, not protruding either forward or downwards; metasternal lobe exhibiting deep median sulcus, with wide lateral depression tapering gradually towards apex; spiracles on 6th abdominal sternite forming typical tubercular projection on each side; abdominal sternites with marked concavity at centre ( Figure 1B). Aedeagus: Parameres much shorter than pars basalis, approximately 1/3 of total length; dorsal lobes complex with apical region subdivided into three distinct areas: (1) outer part forming light oblong protuberance with ciliate surface, (2) median part forming dark disc-like tranverse and ventrally curved projection, (3) inner part forming dark, elongate and arched spinal projection ( Figure 2C-E); ventral lobes as wide as dorsal ones, but extremely short and interrupted by protrusion of outer light component of dorsal lobes ( Figure 2E).

Derivatio Nominis
This species is named after the broad region in which it occurs, the Gariep Desert, where it is also part of an endemic community of species highly specialised to the extreme hot and dry conditions that characterize its climate ( Figure 3). pering gradually towards apex; spiracles on 6th abdominal sternite forming typical tubercular projection on each side; abdominal sternites with marked concavity at centre ( Figure  1B). Aedeagus: Parameres much shorter than pars basalis, approximately 1/3 of total length; dorsal lobes complex with apical region subdivided into three distinct areas: (1) outer part forming light oblong protuberance with ciliate surface, (2) median part forming dark disc-like tranverse and ventrally curved projection, (3) inner part forming dark, elongate and arched spinal projection ( Figure 2C-E); ventral lobes as wide as dorsal ones, but extremely short and interrupted by protrusion of outer light component of dorsal lobes ( Figure 2E).

Derivatio Nominis
This species is named after the broad region in which it occurs, the Gariep Desert, where it is also part of an endemic community of species highly specialised to the extreme hot and dry conditions that characterize its climate ( Figure 3).

Distribution
All specimens and observations currently available are either from the South African or the Namibian side of the Orange River valley, from approximately the Richtersveld-Ai-Ais Transfrontier Park to the Augrabies Falls and the western portion of Gordonia ( Figure 9).

Remarks
Specimen size lies in the range of 13.5-14.8 mm in total length and 7.3-8.0 mm in maximum width. The background colour changes substantially across specimens, within a gradient of reddish-brown to dark brown, while the white dorsal maculation shows much of the same variability observed in M. amabilis s. l. The lateral pronotal bands are continuous in virtually all the specimens currently known, with the exception of one from the extreme southwestern range (Oemsberg, Richtersveld), which exhibits bands interrupted into two portions, similar to the pattern observed in M. a. interrupta ssp. nov. described further down. The two lateral elytral maculae are wide and compact, with the anterior predominantly rectangular but the posterior rather triangular in shape. Approximately one third of the specimens known have also a small to minute white spot in subhumeral position, just ahead of the large anterior macula. The discal spots on pronotal base and elytra are always present and rather well-developed, with the exception of the periscutellar and supra-apical elytral pairs, which can be extremely reduced or even absent in some specimens. In two cases, the mid-elytral discal spots are merged with the larger lateral maculae.
Females are slightly stockier than males, have broader protibia but much shorter protarsi and identical tarsal claws. Their metatibia, on the other hand, is narrower than in the males and lack the typical convex carina on the inner surface which is so typical of their male counterparts. Their elytral apical spine is also shorter than in males, while their inner metatibial spur is almost twice as long as in males. Finally, their abdominal sternites are rather straight, by comparison with those of the males, which are markedly concave with median depression at centre.
Adult activity seems to occur mainly in the late summer and early autumn months (Jan-April), coinciding with the period of highest rainfall in the region [14]. Only one record so far reports adult activity in the spring (September). Like many other cetoniines dwelling in desert and other arid habitats, adults emerge immediately after a substantial rainfall event, cf. [15,16]. Most specimens have been observed feeding on a variety of flowers, mainly of stem-succulent shrubs such as Euphorbia gregaria or small trees like Boscia foetida, where adults also gather to form mating aggregations ( Figure 4). Larvae and other early life stages are yet unknown. (Schaum, 1844) ( Microthyrea amabilis (Schaum). [35]: 77. Mausoelopsis lerui Antoine, 2004 (= amabilis heterospila) syn. nov.
As previously reported in several publications, the populations from southern Africa representing this species show a remarkable variability in the size and presence/absence of the small discal spots, both on pronotum and elytra [2,6,9,26]. However, their lateral pronotal bands and subhumeral elytral maculae are rather consistent and geographically distinct. In particular, the pronotal lateral bands are broken into anterior and posterior lobes in the populations from the eastern part of the subcontinent that exhibits a high summer rainfall rate and the central savanna regions ( (Figures 7 and 8). Hence, the new subspecies name, reflects this key character. The specimen from the Melly Collection, currently housed in the MNHG and designated as M. amabilis paralectotype in Holm and Marais [9], is actually a typical example of this new subspecies and indeed originates from "Port Natal", the old name for the city of Durban (ZN). As previously reported in several publications, the populations from southern Africa representing this species show a remarkable variability in the size and presence/absence of the small discal spots, both on pronotum and elytra [2,6,9,26]. However, their lateral pronotal bands and subhumeral elytral maculae are rather consistent and geographically distinct. In particular, the pronotal lateral bands are broken into anterior and posterior lobes in the populations from the eastern part of the subcontinent that exhibits a high summer rainfall rate and the central savanna regions ( (Figures 7 and 8). Hence, the new subspecies name, reflects this key character. The specimen from the Melly Collection, currently housed in the MNHG and designated as M. amabilis paralectotype in Holm and Marais [9], is actually a typical example of this new subspecies and indeed originates from "Port Natal", the old name for the city of Durban (ZN).

Records of the Other
As expected, M. a. interrupta females are stockier than males, have shorter protarsi (approx. same length as protibia), shorter but symmetric protarsal claws, and longer metatibial spurs than males. Their metatibiae are also narrower than the male's and lack the prominent carina on inner surface. Their abdominal sternites are straight to slightly convex at centre, rather than markedly concave with median depression like in their male counterparts. Adults of this subspecies are active from early Austral spring (September) through the summer to mid-autumn (May). They are attracted to fermenting fruits, sap flows, and especially flowers. Among the flowering plants most commonly visited by M. amabilis s.l. are Bauhinia sp., Catophractes alexandri, Cirsium vulgare, Grewia sp., Protea caffra, Rosa spp., Terminalia sericea, Vachellia spp., Zantedeschia aethiopica, and various Asteraceae [9,36] (pers. obs.).
Larvae of M. amabilis s. l. have been reported as breeding in cattle, goat, and horse dung [9] and have also been found in nursery potting soil in Cape Town [36]. Holm and Marais [9] have further reported that adult individuals have been retrieved from birds' nests, indicating that these may also serve as breeding ground for their larvae. A concise but sufficiently diagnostic description of the larva has been reported by Donaldson [37]. Given that the larvae used in this description were reared in the laboratory from adults trapped at the Pretoria Horticultural Research Institute [37], it can safely be assumed that they represented the nominal subspecies. According to Malec andŜípek [11], populations from Zambia (presumably M. a. interrupta) and Tanzania (presumably M. a. heterospila) have been successfully reproduced in captivity. Apparently, larvae from both populations do not undertake diapause in any phase of their development and normally form a cocoon within a period of 3-4 months from hatching. They prosper in rather dry substrates containing a mixture of rotten wood, leaf litter, and soil [11].

Discussion
Even though what was previously regarded as a desert population of the nominal subspecies is now recognised as a separate species (i.e., Mausoleopsis gariepena sp. nov.), M. amabilis s. l. exhibits an extraordinary variability in its dorsal ornamentation and habitat characteristics, which has caused remarkable confusion and controversy throughout the literature of its description and revisions (cf. [6] and references therein). The basic structure of its dorsal white maculation consists of one broad band on each pronotal lateral margin, a pair of maculae on each elytral margin and a single macula on each elytral apex. In addition to these, there is a pair of smaller spots in the suprascutellar area of the pronotal posterior margin, as well as 1-3 pairs of similar spots of variable size on the elytral disc. Specimens from East and West Africa, however, also exhibit two extra smaller spots on the elytral lateral margins, below the humeral and apical calluses, respectively. In specimens from the eastern range, the first one can take the shape of an elongate projection of the main macula ( Figure 10H,I). Finally, specimens from both East and West Africa also exhibit mesepimeral and metepisternal spots, but these are only fully developed and entirely coalesced only in the extreme western range ( Figure 10J  Thus, what is observed in essence is a progressive fragmentation and proliferation of white cretaceous maculation on the dorsum of the species, with the most coalesced configuration seen in the south-western populations (M. a. amabilis) and the most dispersed in the north-western populations (M. a. ruteri) (Figure 10). Although the configuration of the aedeagal parameres is very conservative across the various populations, a clear pattern of progressive decrease in the elevation of the apical projection of the dorsal lobe (with corresponding increase in distance between inner and central projections) can be seen moving from the south-and northwestern populations (M. a. amabilis and M. a. ruteri) to the southeast (M. a. interrupta) and then to the northeast (M. a. heterospila), particularly in lateral view (Figure 11). Mausoleopsis a. ruteri from the west also shows some typical lateral expansions on the central lobe towards the external one, best visible in frontal view ( Figure 11). In summary, the following identification key can be proposed at this stage to systematically clarify the variability observed within the species. The potential addition of a molecular DNA analysis in the future would certainly be beneficial, in order to conclusively resolve the complex taxonomy of this species. In particular, this may help to better understand some apparent outliers of M. a. amabilis found in the central highlands of Tanzania, which may possibly represent a different taxon. Specimens from coastal East Africa, including the broad region between Mombasa, Zanzibar, and Dar es Salaam as well as neighbouring areas, show the consistent pattern described by Gerstaecker [5], with oblong white stripes on pronotal margins uninterrupted and the large subhumeral maculae exhibiting a narrow anterior lobe projected forward along the margin. Thus, it is proposed here that M. a. heterospila be reinstated as valid parapatric subspecies, along with M. a. ruteri. Their status as subspecies is further supported by observations that intermediate forms are found along the transitional zone between different populations ("overlapping sites" cf. [11]), as expected, rather than randomly across the entire distribution range of the species. Their distribution range is only apparently disjunct (Figure 9), and this is probably because there have been no proper investigations carried out in the countries that lie in between (CAF, SSD, COD-N), due to the persistent inaccessibility of these areas. On the other hand, M. lerui Antoine, 2004, described on the basis of only three types from Malindi (about 100 km north of Mombasa) and Diani Forest (35 Km south of Mombasa), does not show any key diagnostic character separating it from its sympatric M. a. heterospila. The characters considered by Antoine [6] were of relatively minor diagnostic value and are actually quite variable in the numerous material that has become available since the original description. The structure of the aedeagal parameres and the rest of the morphology are also not different to those of the variational gradient observed in M. a. heterospila (Figures 10 and 11). Thus, the most logical conclusion that can be drawn from this is that M. lerui actually represents an extreme variation of M. a. heterospila, and therefore it is here synonymised with it.
In summary, the following identification key can be proposed at this stage to systematically clarify the variability observed within the species. The potential addition of a molecular DNA analysis in the future would certainly be beneficial, in order to conclusively resolve the complex taxonomy of this species. In particular, this may help to better understand some apparent outliers of M. a. amabilis found in the central highlands of Tanzania, which may possibly represent a different taxon.
Mausoleopsis amabilis: Key to Subspecies 1. Lateral margin of elytron with two simple, large white maculae, squarish or triangular in shape; mesepimeral and metepisternal white spots absent, or rarely present but then small and fragmented .. Mausoleopsis amabilis s. l. is a widespread, opportunistic species occurring in most African biomes (mainly Grassland and Savanna), with the exception of the densest tropical rain forests of central Africa, the Succulent and Nama Karoo of southern Africa, and historically the Fynbos of the southwestern Cape [36]. It has recently expanded its distribution range remarkably across the western part of South Africa. Despite Algoa Bay representing its type locality in the original description by Schaum [4], the species was mentioned by Péringuey [26] as occurring throughout South Africa with "the exception of the Cape Colony". Holm and Marais [9] reported the species as widely distributed from southern to western Africa, skirting the Congo basin. The distribution map presented in the latter work seems to confirm its historical absence from the present day three Cape provinces [9: 253, fig. 142i]. However, the numerous observations and data that have recently become available show that now the species occurs widely throughout the three Cape provinces, with the exception of the coastal Namaqualand and the driest part of the Karoo interior ( Figure 9).
Its arrival in the coastal region of the Western Cape appears to be part of a southward range expansion, possibly related to artificial transport of nursery plants with colonised potting soil [36], or to the phenomenon of poleward migration in response to global warming [38,39]. It seems likely that both factors are actually involved in this process, given the migration pattern similarities observed with other insect species in the region [36,40]. Within the Cape Town metropolitan area, it was first recorded near Somerset West in 1999 and has since been found in great abundance throughout the city itself and across the entire Cape Peninsula, at least since 2002. Currently, it is regarded as one of the most common cetoniine in the gardens of the whole Cape Town metropolitan area and has also spread to the southern coastal areas, such as Hermanus and Franskraal, as well as the Cape Garden Route, especially in and around the town of George [36].