Afromosia, a New Robber Fly Genus from Cameroon (Diptera: Asilidae: Laphriinae: Atomosiini)

ABSTRACT Afromosia, a new monotypic genus of Afrotropical Asilidae (Laphriinae; Atomosiini), is described, illustrated and discussed. The type species, A. barkemeyeri sp. n., is recorded only for the West African country of Cameroon. The new taxa are discussed and a key for the separation of Afrotropical Atomosiini is provided.


INTRODUCTION
The asilid tribe Atomosiini (subfamily Laphriinae), which has also been treated as a subfamily (Atomosiinae), is relatively poorly represented in the Afrotropics. Londt (1982) revised the Afrotropical representatives, reporting only nine described species in three genera. Although the tribe is best represented in the Neotropical Region, where more than 140 species, in over 20 genera, have been catalogued (Martin & Papavero 1970), it has known representatives in all major regions: (18 species (10 genera) were catalogued for the Australasian and Oceanian Regions (Daniels 1989); 16 species (4 genera) have been catalogued for the Nearctic Region (Fisher & Wilcox 1997); 6 species (6 genera) were catalogued for the Oriental Region (Oldroyd 1975); 3 species (2 genera) have been catalogued for the Palaearctic Region (Lehr 1988)).
A brief taxonomic overview of the tribe, in an Afrotropical context, is as follows: Hermann (1907) -Described Atomosia argenteoviridis from South Africa. De Meijere (1914) -Described the genus Dichaetothyrea from the Oriental Region (Java).
Keys were provided for all species handled. Dikow (2009) -Undertook a phylogenetic study of world Asilidae in which he included African species Goneccalypsis argentioviridis and Loewinella nigripes. His study suggested the inclusion of Orthogonis Hermann, 1914 andSmeryngolaphria Hermann, 1912 in the Atomosiini. Although Dikow's (2009) phylogenetic study has pointed to the inclusion of Orthogonis and Smeryngolaphria in the Atomosiini, his material (O. scapularis (Wiedemann, 1828) and S. numitor (Osten-Sacken, 1877)) was not of Afrotropical origin. While a single Orthogonis (O. madagascarensis Bromley, 1942) and two species of Smeryngolaphria (S. pallida Bromley, 1935 andS. bromleyi Londt, 1989) are known from the afrotropics, these species do not appear to conform well to the type species, and so I believe that further research is required before their inclusion in the Atomosiini can be confirmed. Certainly, Londt's (1989) study of Afrotropical Smeryngolaphria does not support its inclusion in the tribe. With these reservations, I reiterate that at the commencement of this study there were, as stated above, only nine Afrotropical species in the tribe -a single species of Dichaetothyrea, two species of Goneccalypsis and six species of Loewinella.
It was with considerable interest that I learned of interesting material collected in the West African country of Cameroon that appeared to represent an undescribed species, belonging to an undescribed genus. This belief can now be confirmed, and this paper contains the description of this interesting new taxon and provides a new key for the separation of the four genera of Atomosiini now recognised from the Afrotropical Region.

MATERIAL AND METHODS
Specimens from Cameroon recorded in this study were sent to me by two North American institutions, one of which has allowed a specimen to be retained by me to be housed in the KwaZulu-Natal Museum. Institutional abbreviations used in this paper are as follows (together with the names of colleagues at these institutions that have assisted me): EMF -Personal collection of E.M. Fisher, Sacramento, USA (E. Fisher); NMSA -KwaZulu-Natal Museum, Pietermaritzburg, South Africa (B. Muller); USNM -National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. (T. Dikow). All the material was double mounted using minuten pins and preserved dry. Wings and genitalia were removed for photography and illustration. Male terminalia were macerated in dilute KOH before being drawn with the aid of a drawing tube and then stored in vials containing a mixture of ethanol and glycerine which were attached to the pins. Female terminalia were not dissected.

TAXONOMY
The Tribe Atomosiini is a relatively poorly defined tribe of the subfamily Laphriinae. These flies are known for their small size and dark pigmentation. Although the most important defining character appears to be a completely sclerotised postmetacoxal bridge, the somewhat larger representatives of two Madagascan genera, the monotypic Katharma Oldroyd, 1960 andKatharmacercus Tomasovic, 2014 with two species, share this character. In addition many species have a distinctive wing venation where the base of vein M 2 lies nearly parallel to M 3 and often abutting it, or almost so. This character is also found in some genera not believed to belong to the Atomosiini (e.g. Orthogonis).
Afromosia gen. n. Etymology: A combination of the words 'Afrotropical' (the region from which the genus is described) and 'Atomosia' (a widespread and well known Nearctic and Neotropical genus belonging to the tribe). Type species: Afromosia barkemeyeri sp. n. by present designation and monotypy. Diagnosis: Tiny atomosiine Asilidae (wing length < 7 mm) with the following combination of characters: Head: Antennal postpedicel well-developed, terminal style reduced to a seta-like sensory element situated just beyond mid-length on dorsal surface (Fig. 3). Thorax: Mesonotum lacking a pair of small macrosetae on anterior margin; anepisternum with a single well-developed macroseta on posterior margin; scutellum with an apical tubercular projection (Fig. 4); anatergite asetose; postmetacoxal area strongly sclerotised; wing with base of vein M 2 lying nearly parallel to M 3 , but displaced from it ( Fig. 5). Abdomen: Terga strongly sclerotised, T8 greatly reduced such that only seven terga are clearly visible; sterna weakly sclerotised; ♂ terminalia rotated through 180°.

Afromosia barkemeyeri sp. n.
Figs 1-10 Etymology: Named in honour of Dr Werner Barkemeyer, who has contributed greatly to the knowledge of Afrotropical Diptera through his extensive fieldwork.
♀ genitalia (Figs 9): Simple (not dissected), terminal segments not extended to form an obvious ovipositor. Variation: The ♂ and 2♀ from Limbe are distinctly paler than other specimens (Fig. 1). However, an examination of the ♂ terminalia confirm that this material is conspecific. The following discrepancies are common to all three Limbe specimens. Head: Dark red-brown, mystax entirely pale yellow, 5 occipital macrosetae behind each eye. Thorax: Dark red-brown, katatergal macrosetae entirely yellowish. Femora, tibiae and tarsi uniformly brown-yellow.   Distribution, phenology and biology: The genus and species is known only from Cameroon where it has been collected during March and April. Dr Werner Barke meyer (pers. comm.) kindly provided additional information about the localities where he collected specimens. The type locality (Réserve Forestière) is described as 'Woodland with some human impact (i.e. some banana trees, tree felling etc.)'. The habitat of the Eseka material is described as 'a strip between a roadside and a small stream; wet in parts with some old, rotten tree stumps'. The Limbe (= Victoria) locality is described as 'a hilly area with some small streams and patches of woodland. There were several Manioc, Banana and Mango trees. Apparently an old forest, but now partly cleared for farming'. Although it appears that the species may be associated with woodland it may, like many other Afrotropical Atomosiini, inhabit long grass. Like many grass inhabiting asilids the female has simple terminalia suggesting that eggs are merely allowed to drop to the ground and that no specialised oviposition behaviour exists.
Key to the genera of Afrotropical Atomosiini Adapted from Londt (1982)  New records for Afrotropical Atomosiini In order to plot all available data relating to Afrotropical Atomosiini (Fig.10) the follow ing previously unpublished records for two species are provided: Goneccalypsis argenteoviridis (Hermann, 1907)

DISCUSSION
Afromosia is a distinctive element of the Afrotropical asilid fauna. Dikow (2009), in his phylogenetic study of the Asilidae, was able to highlight a clade formed by the two dominant African genera, Goneccalypsis + Loewinella, characterised by three autapomorphies. Afromosia does not belong to this clade. Although the genus differs in a number of respects from the three other Afrotropical genera, especially with respect to antennal form, it should be noted that the absence of a terminal style, and possession of a subterminal seta-like sensory element, as seen in Fig. 3, is not unusual within the tribe. If comparisons are made with the antennal illustrations provided by Hull (1962), it is obvious that Afromosia resembles all of the following genera (Hull'  (278), Lycosimyia (286), Hodites (286), Aphestia (292). It is significant that all these genera are Neotropical, and so it is tempting to suggest that Afromosia is likely to be more closely allied to Neotropical taxa than to other Afrotropical ones. It should be noted, however, that while a subapical seta-like sensory element may be most commonly encountered in the Atomosiini, it is not unknown in other subfamilies and tribes (see for example Hull's (1962) illustrations of Taracticus (177) and Cyrtophrys (180)). Londt (1999) described a species of Afroscleropogon (Stenopogoninae) with a similarly situated sensory structure (i.e. A. bullingtoni Londt, 1999). Of interest is the wide distribution of Afrotropical Atomosiini (Fig. 10). Although sampling of these tiny flies has by no means been adequate, Goneccalypsis appears to be restricted to montane grasslands in southern and south-eastern Africa. Loewinella, on the other hand, has a much wider distribution and is found in a variety of different habitats where it is also associated with vegetation dominated by grass. Little is known of the habitat occupied by Madagascan Dichaetothyrea, but both known localities appear to be dominated by high altitude savannah, suggesting a more likely association with grassland rather than with forest. Afromosia has been collected in woodland and semideveloped rural settings where it may well inhabit grass.