Fishermyia stuckenbergi, a New Genus and Species of Afrotropical Robber Fly from Madagascar (Diptera: Asilidae: Stenopogoninae)

ABSTRACT A new robber fly genus, Fishermyia gen. n., is described to accommodate F. stuckenbergi sp. n., collected in the Andohahela National Park in southern Madagascar. A revised key to the genera of Afrotropical Stenopogoninae possessing setose anatergites is provided. A brief résumé of Madagascan Asilidae is presented, together with comments on the genera of Oriental Stenopogoninae, which support the contention that this new discovery is of considerable interest.


INTRODUCTION
The Afrotropical stenopogonine Asilidae have received a great deal of attention over the past thirty years and are now known to be the dominant subfamily within the region (Geller-Grimm 2004). A key to the genera of this subfamily was published by Londt (1999), part of which was updated by Dikow and Londt (2000) to include a new genus. Genera are conveniently separated into two groups based on the presence or absence of setose anatergites. Those with setose anatergites are segregated into two groups on the basis of antennal morphology. Two genera -Microstylum Macquart, 1838, which is the dominant representative of the subfamily in Madagascar (about 30 Daspletis Loew, 1858, a genus of eight species known only from southern Africa (Londt 2010) -have the antennal postpedicel (third segment) tipped with a simple pit enclosing a "seta-like sensory element" while the remaining six genera possess a distinct terminal style and have not until now been recorded from Madagascar. The only other possible representative of this large and diverse subfamily to have been recorded from Madagascar is a single species of Oligopogon Loew, 1847, a genus for which the taxonomic position within the subfamily remains debatable (Dikow 2009).
It was, therefore, of considerable interest when representatives of a stenopogonine genus with setose anatergites and also a well developed antennal style were recently isolated from collections made at two localities in the southern parts of Madagascar by a team of scientists led by Dr Michael Irwin. The material was Malaise trapped in ethanol before being extracted and mounted by Dr Eric Fisher who then alerted me to its existence. Believing the specimens possibly to represent an undescribed species of Dogonia Oldroyd, 1970, a genus I had fairly recently reviewed (Londt 2008), Dr Fisher kindly sent the specimens to me for study. Not only is this species new to science, but it represents an undescribed genus. This paper is devoted to the description of this interesting asilid and brief comments on its position within both the Afrotropical and Oriental faunas.
The material is housed in the collections of the California Academy of Sciences (CAS) and KwaZulu-Natal Museum (NMSA). TAXONOMY Genus gen. n. Etymology: This genus is named for my much esteemed colleague Eric Fisher, whose knowledge of the Asilidae is legendary. Not only did he sort through many thousands of Malaise-trapped insects from Madagascar, but he immediately recognised the interest and importance of the material described in this paper. Feminine gender. Type species: Fishermyia stuckenbergi sp. n. Diagnosis: Stenopogoninae with the following combination of characters: postpedicel more than 1.5× longer than scape and pedicel combined and bearing a distinct style made up of three elements, including a terminal "seta-like" element; mystacal setation veloped setae are present, but these are never as strong as mesonotal macrosetae); scutellum with a single pair of apical macrosetae; postmetacoxal area entirely membranous and asetose; only abdominal T1 with a group of strong macrosetae dorso-Key to genera of Afrotropical Stenopogoninae with setose anatergites Fishermyia; it however excludes Oligopogon because of uncertainty of its subfamilial assignment) 1 Postpedicel (= third antennal segment) tipped with a small apical pit enclosing a "seta-like" sensory element. Male. Head (Fig. 2): Dark red-brown, white and black setose, silver to dull grey pruinose. Antenna (Fig. 7): Dark red-brown, scape and pedicel white setose (pedicel may have a single black seta distolaterally); segmental ratios 1.0:1.0:3.3:0.5, scape and pedicel of similar length, postpedicel more than 3× length of scape, style half length of scape. Style with 3 elements, short basal ring-like segment and longish central segment tipped by spine-like sensory element. Face dark red-brown ventrolaterally, brownorange centrally (colour considerably masked by pruinescence); mystax white, conventrolateral parts; face:eye-width ratio (measured anteriorly at widest level of head) 1.0:1.7 (i.e tuberant ventrally. Frons and vertex (including ocellar tubercle) dark red-brown, longish black setose, entirely dull grey pruinose. Occipital region dark red-brown, white setose, silvery pruinose; setae both well developed (along eye margins and posterior of ocellar tubercle) and thin and wavy (mainly ventrally). Palpus: 2-segmented, dark red-brown, fairly longish white setose. Proboscis: dark red-brown, long, jutting out well beyond epistomal margin, fairly straight (slightly downwardly curved distally), white setose basoventrally. Thorax: dark red-brown to black dorsally, mainly brown-orange laterally, black and white setose, strongly silver pruinose. Pronotum dark red-brown to black, white setose, antepronotum with row of moderately developed macrosetae, silver pruinose. Prosternum orange-brown asetose, silver pruinose. Mesonotum blackish, except for dark red-brown postpronotal lobes, short black setose (except for few white setae posterolaterally), strongly silver pruinose (except for pair of darkish longitudinal fasciae which appear more weakly pruinose, depending on angle of view); major macrosetae black, 2-3 postpronotals, 2 notopleurals, 1 supra-alar, 2 postalars, acrostichals undifferentiated, 3-5 pairs of dorsocentrals mostly posterior of transverse suture. Scutellum dark red-brown, weakly white setose anteriorly, a single pair of black apical macrosetae, silver pruinose. Pleura brown-orange, white setose, silver pruinose (except for small except for moderately developed katatergals. Mediotergite and anatergites orangebrown, silver pruinose; anatergites white setose posteriorly. Legs: Coxae orange-brown, longish white setose, silver pruinose. Trochanters red-brown, white setose, apruinose. but narrowly orange-brown proximally. Pulvilli pale cream. Empodia well-developed, specimens with wing lengths ca 9.5, 12.2 (holotype) and 12.3 mm (wings somewhat twisted). Membrane transparent, unstained and without microtrichia. Venational features: Costal cell sometimes with distal crossvein (in 2 specimens); all marginal cells open except for m 3 which is closed and stalked; veins CuA 2 and A 1 either narrowly separated or converging at wing margin (therefore cell m 3 open or closed). Haltere: Creamy white with pale brownish base. Abdomen: Generally slightly broader than deep. Terga dark red-brown to black, laca 5 pale yellowish macrosetae posterolaterally, entirely silver pruinose (weakly subapically). T2-7 lacking macrosetae, largely apruinose, except for strongly silver pruinose broad lateral margins. T8 largely obscured from view, uniformly dark red-brown. Sterna apruinose lateral margins.
processes best seen in ventral view (Fig. 6) and medially directed downwardly pointing bifurcate tips best seen in lateral view (Fig. 4). Gonostylus, best viewed laterally (Fig. 4), moderately developed, laterally compressed, upwardly curved with rounded distal end. Hypandrium well developed; in ventral view (Fig. 6) broad proximally, tapering fairly rapidly to laterally compressed distal lobe terminating in an almost bilobed distal end.
Female. Unknown. Distribution, phenology and biology: Known from two localities in southern Madagascar (Fig. 8). Collected in December, February and April, it is assumed that this species is on the wing during summer. No biological information has been recorded, but see Discussion below.  (Irwin et al. 2003). In some respects the asilid fauna of Madagascar has been better studied than that of the African mainland. There are currently 34 genera recorded for Madagascar (Table 1), eight of which are recorded only from the island (Caroncoma, Cerdistus, Dichaetothyrea, Fishermyia, Katharma, Michotamia, Orthogonis and Schildia) and not from elsewhere in the afrotropics. In addition there are two genera (Lycoprosopa and Cophinopoda) which are not known from the African mainland, but have been recorded from other Indian Ocean Islands within the afrotropics. Of the remaining 24 genera only three have species that have also been recorded from the African mainland (Loewinella nigripes Engel, 1929, Storthyngomerus tridentatus Fabricius, 1805and Clinopogon nicobarensis Schiner, 1868; all their other species are Madagascan endemics. Of particular interest is the generic representation of subfamilies. While all the Afrotropical subfamilies are represented, some are far better represented than others. The Trigonomiminae is fully represented (i.e., 100 % representation) as both Afrotropical genera have been recorded on Madagascar. Three subfamilies (Dasypogoninae, Ommatiinae and Stichopogoninae) are well represented (67 % of genera), while others are relatively poorly represented, Leptogastrinae (50 %), Laphriinae (32 %), Asilinae (24 %). In stark contrast to the African mainland, the least represented subfamily is the Stenopogoninae (7 %). This is hardly surprising as members of this subfamily are adapted for oviposition directly into sand or soil and are therefore best represented in arid, sandy biomes which are relatively poorly represented in subtropical Madagascar which is, at least until fairly recently, dominated by forest biomes. The discovery of Fishermyia is therefore Oligopogon is placed), within the Stenopogoninae to be found in Madagascar. The other genera, Microstylum and Oligopogon, are far more widely distributed, Microstylum being a very large and almost cosmopolitan genus (Geller-Grimm 2004).
Because it is well known that the Madagascan fauna is a blend of both Afrotropical and Oriental elements, it is necessary to eliminate the possibility that the newly discovered species is a representative of an established Oriental genus. The writer is not an authority on Oriental Asilidae, and unfortunately the most recent Oriental Diptera Catalogue (i.e., Oldroyd 1975) is somewhat outdated and of limited value. The recent world catalogue of asilid genera published by Geller-Grimm (2004), however, allows a modern list of Oriental genera to be assembled. Only nine stenopogonine genera are listed for the region (Ancylorhynchus Berthold, 1827, Connomyia Londt, 1992, Cyrtopogon Loew, 1847, Grypoctonus Speiser, 1928, Microstylum, Neoholopogon Oldroydia Hull, 1956, Scylaticus Loew, 1858and Stenopogon Loew, 1847. As a student of Afrotropical Asilidae the author is well acquainted with Ancylorhynchus, Connomyia, Microstylum, Scylaticus and Stenopogon, as they are well represented in the afrotropics, and so can testify with certainty that the Madagascan species does not belong to any of these. The writer is also familiar with Cyrtopogon, having been instrumental in the transfer of species recorded for the afrotropics to Afroholopogon Londt, 1994(Londt 1994 and is, therefore, certain that the Madagascan species described above does not belong to this genus. While not familiar with Grypoctonus, Neoholopogon and Oldroydia, having not examined representatives of these genera, his interpretation of Hull's (1962) world generic study and more recent publications by Joseph andParui (1989, 1999) and Parui et al. (1999), where representatives of these genera are described, illustrated and discussed, strongly suggests that this new Madagascan species cannot be assigned to any of these genera. It seems certain, therefore, that Fishermyia is indeed a new Madagascan endemic.
Having been Malaise-trapped, little is known regarding the biology of Fishermyia stuckenbergi. Both localities are within the Andohahela National Park. The habitats are described as "transit. For." (i.e., transitional forest) and "dry spiny forest", which suggests that the habitat is of a more open woodland type. The fact that all the collecin traps, samples are often dominated my male specimens (e.g., Ancylorhynchus, see that differ from those of their female counterparts. Insects that have fairly sustained collected in Malaise traps. It is, therefore, likely that the males of F. stuckenbergi in a more sustained manner than their female counterparts.