Revision of the Afrotropical Species of Parapachycerina (Diptera: Lauxaniidae)

ABSTRACT Parapachycerina Stuckenberg, a genus of small, usually yellow-orange sapromyziform lauxaniids (Diptera: Lauxaniidae) restricted to the Old World, is redescribed. The African and Malagasy representatives are revised, with four new species described: P. bispina sp. n., P. infuscata sp. n., P. lalitra sp. n. and P. talea sp. n. There are now five Afrotropical Parapachycerina species, including the type species, P. munroi Stuckenberg, 1971. Further, the paper provides an identification key to the Afrotropical species, a summary of the available biological information, and preliminary remarks on the phylogenetic relationships of the genus.

The lauxaniid fauna in sub-Saharan Africa, as elsewhere in the world, is found principally in forest (e.g. Homoneura van der Wulp, Cainohomoneura Stuckenberg, Prosamyza Stuckenberg), moist savannah and grassland (e.g. Chaetolauxania Kertész, Diplochasma Knab), and shows low species richness and diversity in arid regions (e.g. <2% of lauxaniid specimen lots in the Natal Museum Diptera Collection originate from the drier, western provinces of South Africa, viz. Northern Cape, North-West and Free State).
Despite the widespread occurrence and diversity of lauxaniids in sub-Saharan Africa, little research has been published on the Afrotropical representatives in recent years. In this paper we revise Parapachycerina. The genus was erected by Stuckenberg (1971: 539) and, to date, only three species are recognized in the published literature (Shewell 1977;Miller 1980;Evenhuis & Okadome 1989): the type species, P. munroi Stuckenberg, 1971 and two Oriental species (both originally described as Lauxania species), P. hirsutiseta (de Meijere, 1910) and P. cuneifera (Kertész, 1913).
In his major review of Old World lauxaniids, Stuckenberg (1971: 588) indicated that 'there are a number of species of Parapachycerina in tropical Africa, all undescribed, and these will be dealt with fully in a forthcoming monograph'. Later events precluded the production of this monograph, and it is the task of this paper to describe these new African and Malagasy Parapachycerina species.

Diagnosis:
P. bispina is broadly sympatric over much of Africa with P. munroi, and can be separated from that species by: (1) the black ocellar spot not extending back to touch the postvertical setae; (2) wing with light brown infuscations, shading the outer 3/4 of the costal cell, most of the marginal cell and anterior portion of the submarginal cell, anterior and posterior cross-veins (r-m; m-m) and also M 3+4 (vein 5) (P. bispina is the only Afrotropical species in the genus with marked wings, apart from the Malagasy P. talea); (3) the paired, black spines on apex of epandrial process; and (4) pale orange-yellow cerci (dark brown in P. munroi). P. bispina is also sympatric in areas with P. infuscata, but the deep yellow-orange coloration, gently rounded vertex, black ocellar spot and absence of a ctenidium distinguish P. bispina.
The wing illustration purportedly of P. munroi in Stuckenberg (1971: fig. 42) is in fact P. bispina (as it shows infuscation of the cross-veins and anterior portions of the wing). This specimen is noted as a P. munroi paratype in the legend, but no specimen bearing these wing characteristics can be found in the P. munroi paratype series (NMSA), and evidently there was some mix up in the preparation of that figure.

Description:
Colour: Viewed with naked eye and under low magnification, impression is of uniformly rich yellow-orange fly. Occiput yellow. Ocellar spot deep black. Scape, pedicel and postpedicel all yellow, slight darkening at base of arista; pedicel may have orange tinge. Maxillary palpus yellow-orange. Thorax yellow-orange with two orange longitudinal stripes (vittae) on scutum (faint in some specimens), stripes are placed slightly mesad of dorsocentral bristles. Scutum sometimes shows darkening on humeral callus and along border of notopleuron and mesopleuron. Postnotum and postscutellum yelloworange. Scutellum yellow with broad orange medial stripe. Mesopleuron, pteropleuron, sternopleuron, pleurotergite and meropleuron all yellow-orange. Haltere pale yellow. Legs yellowish. Abdomen yellow-orange to dark brown (generally the former). Head: Postfrons fairly strongly sloping, wider than long (3:2). Orbital plates weakly differentiated from surrounding postfrons. Postfrons ending in narrow lip over proximal portion of scape. Prefrons very weakly tumid. Ocellar triangle large and expanded (relative to other Afrotropical Parapachycerina species), anterior ocellus nearly reaching level of posterior fronto-orbital bristle; ocellar spot encloses all three ocelli. Thorax: Five or 6 longitudinal, rather irregular rows of setulae between dorsocentral bristle rows. Posterior pair of acrostichals ca 0.5× length of posteriad dorsocentral bristles. Anterior dorsocentral bristle ca 0.5× length of posterior dorsocentral; middle dorsocentral intermediate in length. Weak, barely visible pruinosity on scutum. Two sternopleural bristles, posterior bristle more robust and longer (area around bristles generally bare of setulae; ventrally usually a patch of ca 20 setulae). Pteropleuron, meropleuron, pleurotergite and prosternum bare of bristles and setulae. Legs: No ctenidium on profemur, in that area ca 8 widely-spaced, weak setulae. Profemur posteriorly with ventral row of ca 3 strong, widely-spaced setae and dorsal row of ca 6 equally strong setae. 2 short spurs on posterior, distal edge of protibia, outer spur is ca 2× length of inner spur. Procoxa has ventral row of ca 4 or 5 setae and few scattered setulae. Mesocoxa has fan of ca 6 setae (no setulae visible). Mesofemur strong, anteromedial row of 5 robust, proclinate setae, posteriorly largely bare. Metacoxa largely bare, but 2 strong setae on opposite margins of coxa. Metafemur with unexceptional vestiture of ca 6 irregular rows of setulae on anterior face. Wings: Mostly hyaline, but distal 3/4 of costal cell, most of marginal cell and anterior section of submarginal cell, anterior and posterior cross-veins (r-m, m-m) and M 3+4 (vein 5) light infuscated (in some specimens infuscation very pale and requiring careful discrimination). Male terminalia (Figs 17,23): Protandrium roughly ring-shaped in transverse view, having small ventral processes, in lateral view fairly narrow dorsally and tapering laterally (slightly less so than in type species, P. munroi). Epandrium moderately broad dorsally, expanding posterolaterally, before tapering to small, rounded epandrial extension, at apex of epandrial extension characteristic stout, paired, black setae, in extracted genitalia inclinate, interdigitate with opposing pair, lower seta of each pair is longer than upper seta (upper seta is ca 0.8× length of lower seta). Surstylus hidden in lateral view, fused to inner medial margin of epandrium. Surstylus relatively large (in relation to aedeagus), flattened dorsoventrally, blade-like, tapering posteriorly to acute point and with mediolateral mucro. Surstyli closely associated with aedeagal complex (could on initial examination be considered to be gonopods). Cerci pale yellow. Hypandrium composed of broad 'transverse band', short, weakly lateroclinate anterior arms and longer, inclinate posterior arms that curve upward to terminate near base of gonopods and lateral edges of aedeagus (in ventral view, hypandrium resembles a 'wobbly' H). Hypandrial 'transverse band' broader than 'aedeagal tube'. Aedeagal apodeme approximately same length as aedeagus, bifurcating beneath 'dorsal arch' of aedeagus. Aedeagus composed of two halves ('wings') that taper posteriorly, halves meet anteriorly in 'dorsal arch'; posteriorly each 'wing' is bifurcate, subapically each half (wing) has ventrolateral mucro. Medially, aedeagus is membranous. Gonopods are blade-like, lightly sclerotised, broad basally, emarginate subbasally, widening medially and tapering to acute apex. Parapachycerina infuscata sp. n.
Undescribed taxon B A single female from the lush forest on Montagne d'Ambre, Antsiranana (Diego-Suarez;23.xi-4.xii.1958, B. Stuckenberg, NMSA) appears to represent a new species. For want of more material, it is left undescribed. It resembles P. talea in being a robust, deep orange Parapachycerina with very lightly infuscated wings. It differs, however, in lacking the posterior extension from the ocellar spot, and in lacking a profemoral ctenidium (a feature which also separates it from the smaller P. lalitra). Other salient features of this specimen are: small ocellar triangle (with sides approximately equal); blackish ocellar spot; postpedicel mostly yellow but darkened apically; sides of notopleuron strongly infuscated; dark orange medial stripe on mesonotum; and 2 sternopleural bristles. The isolated Amber Mt (a forest-clad late Tertiary volcano) is wellknown as a site of local endemism in Madagascar.
Undescribed taxon C The late Loïc Matile collected a distinctive female specimen from Grande Comore, the largest island in the Comoros archipelago (Grande Comore, La Grille (Guiri), 850-900 m, 15.xi.1973, L. Matile, MNHN). Immediately notable about this specimen are the large black spot on the mesopleuron, the weakly fumose anterior part of the wings, three broad, black mesoscutal vittae, and the black marks on the lateral sides of the occiput. The profemoral ctenidium is present. The arrangement, size and orientation of cephalic setation are as per the genus.
This specimen definitely seems to represent a new species, but until further specimens are procured, in particular males, it is left undescribed. The presence of Parapachycerina on Grande Comore hints at the possibility that the genus may yet be found on the Seychelles. Based on superficial colouration similarity and the presence of a profemoral ctenidium, this taxon may be the sister-species of P. infuscata. Interestingly, the three species with profemoral ctenidia are the two Malagasy species and P. infuscata of the African mainland. Taxon C is a geographical annectant step joining these ctenidiabearing Parapachycerina taxa. Whether this is a coincidence, or represents cognate phylogenetic affinity, is still to be determined.

Cladogenesis in Parapachycerina
The low number of species in the genus (seven in total, five in the Afrotropics) is immediately apparent and appears to reflect a limited degree of cladogenesis ('speciation'), but possibly collecting biases or recent extinctions are involved. Although there remains considerable taxonomic work in the Afrotropical lauxaniid fauna, a total of five Afrotropical species is a circumscribed number when compared to genera such as Cestrotus Loew and Homoneura, which have diversified extravagantly in Africa. Other African lauxaniid genera have a similarly limited degree of 'speciation', including presumed near-relatives of Parapachycerina such as Neogeomyza. Why Parapachycerina should have diversified so weakly is unknown.
Some of the differences enumerated above are possibly the result of sexual selection, e.g. differences in male terminalia and variation in the intensity, size and shape of the ocellar spot (a signalling feature?). The inconsistency in the presence of the profemoral ctenidium is, at first glance, perplexing. Profemoral ctenidia are found only in the two Malagasy species (P. lalitra and P. talea) and P. infuscata of Africa, and are absent in P. munroi, P. bispina and P. hirsutiseta (of Asia and northern Australia). The function of the ctenidium is unknown, and we are unaware of any serious functional consideration of this morphological feature in the dipterological literature.  Mathis 1989: figs 11, 12), but their function in these acalyptrate flies is also obscure. The ctenidium is modified in Parapachycerina from a ventral row of ca 10-15 downward-pointing fine setulae. Perhaps it functions to clean the plumose aristae, but there appears to be no unambiguous relationship between the plumosity of the aristae and the presence of profemoral ctenidia. Perhaps of significance, the profemora of sepsids bear armature (Meier 1995: 435-436;Eberhard 2001), which are considered to be adaptations for gripping the females' wings during copulation, but this explanation is unlikely to apply to Parapachycerina as the ctenidium is found in both sexes. Although this paragraph is speculative, we must not lose sight of these functional considerations because features such as the profemoral ctenidium have been given high classificatory and phylogenetic 'weight' by some lauxaniidologists (e.g. Shewell 1987: 953;Yarom 1995). Critical interrogation of the value of presumptive apomorphies is essential to avoid phylogeneticists being misled by uncomplex characters that easily result from convergence.
Constructing a phylogeny for Parapachycerina will not be formally attempted here. Reticence is needed because the differences between species are subtle, the characters themselves are of low complexity, their distribution amongst the members of the genus is not congruent, and the full diversity of taxa in Asia and Australia is as yet unknown. Evidence from the male terminalia suggests that P. munroi, P. infuscata, P. lalitra and the Oriental P. hirsutiseta (see Sasakawa 2003: fig. 2) form a clade to the exclusion of P. bispina (P. talea and the Oriental P. cuneifera are ignored here because the male terminalia are unknown). P. bispina is distinctive by having the two robust setae at the apex of the epandrial process, a unique condition in the genus. P. bispina also has a distinctive surstylus, which is not visible in lateral view. The surstyli in other Parapachycerina species are narrow, laterally-compressed lamellae with hamate apices, whereas in P. bispina the surstylus is a dorsoventrally flattened blade that lacks the dorsal apical hook. It is unfortunate that the male terminalia of P. talea are unknown, because this species, like P. bispina, has the anterior part of the wing slightly smoky and also resembles P. bispina in general size, shape and colour. In contrast to the postabdominal evidence, the presence of the profemoral ctenidia would suggest a clade consisting of P. lalitra, P. infuscata and P. talea to the exclusion of P. bispina, P. hirsutiseta, and P. munroi (we are unaware of the condition of the profemora in the Oriental P. cuneifera).

Phylogenetic considerations
Is Parapachycerina a monophylum? Unambiguous apomorphies for the genus are elusive, but the surstylus has an unusual, distinctive shape, arising on the inner margin of the epandrium and resembling a tiny, laterally compressed finger; it is possibly a synapomorphy. For the present, the notion of Parapachycerina as a monophylum appears a defensible position, given its unique combination of characters.
Accepting, pro tempore, Parapachycerina as a monophyletic entity, the next question is: what is its sister-clade? The senior author was initially strongly impressed by the similarity of the genus to the Neotropical Neopachycerina. This South American genus was described by Malloch (1933: 357, fig. 67c) on the basis of six specimens from Montevideo, Uruguay (with the single species, N. aristata). Neopachycerina looks a lot like Parapachycerina-both are small, orangish lauxaniids with black ocellar spots, plumose aristae, small anterior fronto-orbital bristles, generally hyaline wings and sapromyziform costae. The two genera also key out in the same couplet in Stuckenberg's (1971) generic key (couplet 32), although Stuckenberg warned that the resemblance was possibly 'a case of convergence'.
Differences shown by Neopachycerina include: a more protuberant ocellar hump; dense ocellar setulae (lacking in Parapachycerina); the presence of tiny setulae on the anterolateral portions of the postfrons (absent in Parapachycerina); a conspicuous lunule; a very weak anterior sternopleural bristle; stout, costal setulae terminating well short of R 4+5 (approximately half way); and densely plumose arista (loosely plumose arista in Parapachycerina). Compared to Parapachycerina, the male terminalia of Neopachycerina (Fig. 31) show noteworthy differences in the shape of the protandria and aedeagal complexes. The protandrium of Neopachycerina is bonnet-like, lengthened longitudinally and shortened laterally in comparison to Parapachycerina species. The protandrium is also incomplete ventrally in Neopachycerina, in contrast to Parapachycerina. The epandria are generally similar in both genera (broader laterally than dorsally). What are interpreted to be the surstyli in Neopachycerina are broadly rounded processes, which are not articulated or fused to the inner surfaces of the epandria, but meet below the cerci. The aedeagus is a navicular (boat-shaped) sclerite with spinules (teeth) posteriorly on the inner subapical surfaces. The aedeagal apodeme is very short (<0.5× length of aedeagus), having an anterior disc and posterior stem (vaguely recalling a ping-pong bat in lateral view), tapering strongly posteriorly to short posterior arms. The hypandrial 'transverse band' is broad with a small 'apron' projecting downwards at an oblique angle; the lateral hypandrial arms are long, and the 'dorsal loop' found in Parapachycerina does not occur in Neopachycerina-instead, the lateral arms curve upwards and inwards forming an irregularly shaped convolution bearing a tiny lappet that, rather unusually for internal genitalic sclerites, has 2 or 3 setulae; the inner edge of this convolution then fuses with the base of the gonopods. These differences suggest convergence between the two genera. Shewell (1986) had also pointed out convergent similarities in unrelated Old and New World lauxaniid genera.
It was also interesting to note a third row of setulae along the costal margin from between subcosta and vein 1 to ca 60 % of the way down the marginal cell in Neopachycerina, a condition not found in Parapachycerina. This extra row of setulae is a strange condition in lauxaniids, judging from Hackman and Väisänen (1985), who found two rows to be uniform throughout the lauxaniids they examined, but the extra row in Neopachycerina was noted in two co-types examined (part of the type series lodged at the BMNH).
An anonymous referee kindly pointed out to us the genus Tanyura described by Kim (1994: 313-315) from Australia and the Phillipines, which we had overlooked. We have not examined Tanyura, but judging from Kim's description, figures of the terminalia and comparison with Parapachycerina (Kim 1994: 314-315), this genus emerges as a good candidate for sistership. Kim (1994) gave a list of 11 morphological differences between the two genera. With increased knowledge of Parapachycerina some of the differences cited by Kim (1994) are now known to be incorrect; for example, he states that Parapachycerina lacks the profemoral ctenidium, whereas it is present in certain Afrotropical species. Differences that continue to hold include: (a) one mesotibial spur in Tanyura (two in Parapachycerina); (b) Tanyura lacking shorter setulae in plumose arista (these shorter macrotrichia present in Parapachycerina); (c) homoneuriform costa (sapromyziform in Parapachycerina); and (d) elongated, ventrally pointing male cerci (rounded, non-elongated male cerci in Parapachycerina). A potential sister-relationship with an Oriental and Australasian genus also makes far more sense biogeographically than sistership with a South American genus. The senior author must, therefore, concede that he was mistaken in pursuing Neopachycerina as the potential sister-clade to Parapachycerina.
Comprehension of the high-level phylogenetics of the Lauxaniidae is still in a nascent stage, although it has become customary to recognise two subfamilies, the Homoneurinae and Lauxaniinae (e.g. Shewell 1977Shewell , 1987Miller 1980;Evenhuis & Okadome 1989). Stuckenberg (1971) and Miller (1980) did not include Parapachycerina in the Homoneurinae owing to its sapromyziform costa. Shewell (1977) transferred it to the Homoneurinae. He did not provide explanation in the Oriental Catalogue for this move, but in a letter to Miller (11 December 1978) explained that 'the [Parapachycerina] genitalia seem to me typically oriental homoneurine' and referred to a manuscript on Nepalese lauxaniids, in which he intended to discuss the matter further. This paper, based on the Coe collection of Nepalese lauxaniids, regrettably was never published (see Shewell's bibliography in Arnaud 2001).
In an investigation of Homoneurinae monophyly based on parsimony-derived cladograms, Yarom (1995) also found that Parapachycerina grouped within a monophyletic Homoneurinae, specifically with what he termed the 'Katalauxania genus-group lineage'. The latter clade was founded on five synapomorphies. Several of these are, subjectively-speaking, not convincing (e.g. 'eye not round, posterior margin slanting', 'face not prominently inflated') because they are simple characters and appear in other lauxaniids; furthermore, one of the synapomorphies 'surstylus freely articulated' is not correct for Parapachycerina. Returning to higher-level divisions, Yarom's analysis identified several 'highly supportive' synapomorphies for the Homoneurinae: (a) homoneuriform wing; (b) profemoral ctenidium present; and (c) two mesotibial spurs (Yarom 1995: 46-49). These characters had previously been identified as diagnostic for the homoneurines by Stuckenberg (1971: 516-517) and Shewell (1987: 953).
Parapachycerina does not have a typical homoneuriform wing and the profemoral ctenidium is variably present (absent in the type species). The two mesotibial spurs are, however, always present. Although Parapachycerina does not have a typical homoneurine wing (the original definition by Stuckenberg (1971: 501) is 'spinules reach or very nearly reach the apex of R 4+5 where they stop abruptly without marked prior diminution in size'), the setulae do extend ca 75 % of the way to R 4+5 . Other sapromyziform lauxaniids have the setulae terminating well before that (ca 50 % of the way between the two vein apices), as mentioned above with regard to Neopachycerina. It is possible that the recognition of only two costal setulae categories (sapromyziform and homoneuriform) is an artificial one, and rather than two distinct states, a messy series of intermediates reflects reality better. This is also suggested by Kim's (1994: 19) comment that 'in this study numerous species of Trypetisoma with both forms of costa have been identified, and they show different end points of costal spinules between the apices of veins 2 (R 2+3 ) and 3 (R 4+5 )'. Conversely, there are some Homoneura species where the stout, costal setulae end before R 4+5 , notably, H. citreifrons (Malloch, 1920) of the Nearctic (Miller 1977a: 159, fig. 11b) and H. kaszabi Shewell, 1971 andH. amphibola Shatalkin, 1992 of the Palearctic (Shatalkin 2000).
Inconsistency in these 'strong' homoneurine synapomorphies reinforces the view expressed that lauxaniids display pronounced morphological plasticity (Stuckenberg 1971: 500;J.F. McAlpine 1989J.F. McAlpine : 1445. We would also note that these 'strong' synapomorphies comprise morphologically simple characters, respectively: (1) extension by very short distances of costal setulae and slight diminution in length of these setulae (the homoneuriform/sapromyziform dichotomy); (2) strengthening of the row of fine anteroventral setae of the profemur into shorter, stouter setulae (the profemoral ctenidium); and (3) development of one of the mesotibial setula into a robust but short spur (two mesotibial spurs). Although the genetic and selective processes underlying these changes are unknown, it is a legitimate inference that the changes required are not complex. As insightful phylogeneticists have warned (e.g. Bechly 2000: 5-6;Wägele 2004Wägele , 2005, erecting phylogenies on the basis of simple characters is a risky enterprise (irrespective of whether the cladograms are arrived at by putative 'objective', parsimony-aided 'analysis'). As mentioned above, the senior author burnt his fingers badly in contemplating Neopachycerina as the sister-clade to Parapachycerina, an example where conver-gence also can mislead taxonomists, and a phenomenon which Stuckenberg (1971) and Shewell (1986) had warned of.
The phylogeny of lauxaniids will remain a considerable challenge to dipterists in the future until new character systems (e.g. terminalia) can be adequately assessed across the family (Remm and Elberg's (1979) pioneering efforts aside). For now, the drift of consensus is to place Parapachycerina amongst the homoneurines. In the absence of better data, we cannot offer any conclusive opinion, but note either the absence or variability in Parapachycerina of the characters deemed definitive homoneurine synapomorphies by lauxaniidologists.

Historical biogeographical considerations
Parapachycerina displays a distribution pattern typical of innumerable invertebrate and vertebrate clades in being restricted to the Old World tropics, specifically in Africa, South-East Asia and weakly in northern Australia (Shewell 1977;Miller 1980;Evenhuis & Okadome 1989). Parapachycerina is also represented on Madagascar and the Comoros, but not from the Seychelles and Mascarene Islands; possibly future collecting will reveal endemic species on these islands.
The aridity of North Africa and Arabia is (on a geological time-scale) a recent event, beginning in the late Miocene (Pickford 1999(Pickford , 2000Pickford et al. 2006) and intensifying through the Pliocene and Quaternary (with some brief fluctuations). Compelling palaeontological evidence also points to extensive interchange between Africa and Fig. 31. Lateral view of _ terminalia of Neopachycerina aristata Malloch. Note differences from Parapachycerina in protandrium shape and inner gentialia. Abbreviations: aed apo -aedeagal apodeme; eja apo -ejaculatory apodeme; epa -epandrium; hyp -hypandrium; ? sur -probable surstylus.
Eurasian faunae in the Neogene (e.g. Thomas 1985;Pickford 2002). Doubtless proto-Parapachycerina was involved in this mixing of Afrotropical and Eurasian fauna, explaining its presence in much of the paleotropics. As for Madagascar, geological data show that there has been no terrestrial connection between Africa and Madagascar since the Jurassic (de Wit 2003). The Comoros are volcanic Cenozoic islands and the presence there of Parapachycerina taxon C, indicates that the Comoros may have been used as 'stepping-stones' to reach Madagascar.
Acalyptrate flies only began their explosive diversification in the Palaeogene (Hennig 1965;Grimaldi & Engel 2005: fig. 12.78), the oldest putative lauxaniids being from the Eocene and Oligocene (Evenhuis 1994: 433-434). Given the age of the separation of Madagascar from Africa, and the constrained dates of acalyptrate diversification, we must turn to aerial dispersal to explain the occurrence of Parapachycerina on Madagascar.
The circumstantial case for a dispersalist scenario is strong. For example, Chapman et al. (2003: 503, 507) observed that 'millions of metric tons of insects are aloft in Earth's atmosphere at any given moment', and that 'a conservative estimate of the total bioflow over a 1 km stretch of the southern English countryside is an astounding 3 billion insects per month'. These data underline the potency of aerial dispersal in transporting volant insects far and wide, as was borne out from the earlier empirical studies of Holzapfel and Harrell (1968) and Wise (1983), among others. Further, in investigations of the biotic recolonisation of the volcanic island Krakatau (Indonesia), Lauxaniidae were one of the fly families to successfully recolonise the island (Thornton et al. 1990: fig. 13).
In sum, considering these disparate strands of evidence (geological history of Madagascar, potency of aerial dispersal of insects, and rapid colonization of the 'reallife biogeographical experiment' of Krakatau by lauxaniids), the most parsimonious view is that ancestral Parapachycerina reached Madagascar by aerial dispersal. It also appears more plausible to posit colonization of Madagascar from Africa, rather than reverse.
Within Africa itself, Parapachycerina is closely associated with the distribution of tropical and subtropical savannah and moist escarpment grasslands. Current evidence shows that it is absent from the lowland Guineo-Congo rainforest, although occurring at its edges. The genus is largely tropical and subtropical, its range terminating at about 30°S, and at a similar latitude in the north.

Biology of Parapachycerina
Biological information on Parapachycerina is sparse. Most adult specimens have been caught in grassland and at forest/grassland ecotones by sweeping. Only two specimens examined were captured in a Malaise trap (both P. infuscata males from Kenya). The adults are possibly fungivorous, as indicated by the presence of a labellar beak and some pseudotracheal scoops and prongs, which Broadhead (1984Broadhead ( , 1989 showed were adaptations for feeding on phylloplane fungi. We did not notice any fungal hyphae or spores in proboscides dissected, but our preparations were crude. Consequently, confirmation of a fungivorous habit by Parapachycerina calls for further investigation. Perhaps unusually, an adult of P. bispina from Segibwa Falls, Uganda (BMNH) was 'attracted to human faeces' (label datum). Specimens of P. bispina collected by Deeming in northern Nigeria (Tilden Fulani) were taken 'on tomatoes' at a mixed vegetable farm.
The larvae are unknown, but, it is likely that Parapachycerina larvae feed on dead and decaying grass and other vegetable matter, as is the case with grassland-dwelling lauxaniids in general (Miller 1977b), and phylogenetically-related flies in the Celyphidae (Miller 1986) and Natalimyzidae (Miller 1984;Barraclough & D.K. McAlpine 2006).
Parapachycerina adults have been collected alongside other small, mostly yellow lauxaniid species of Diplochasma Knab and Chaetolauxania Kertész in South African grasslands. Parapachycerina is usually not as commonly encountered as these other yellowish lauxaniid genera, and the larger, darker grass-inhabiting Calliopum Strand, Lauxania Latrielle and Mycterella Kertész. Being small flies, Parapachycerina are easily overlooked by collectors, and possibly are more abundant and widespread than reflected in the rather small number of specimens in collections (<200).
Most specimens have been collected at low altitudes (<1000 m), but the genus is known from mid-altitude escarpments in South Africa (e.g. the Mpumalanga Drakensberg) and mountain ranges in Zimbabwe (e.g. the Vumba Mts) and Tanzania (e.g. the Songea highlands).
Interestingly, several species may be found in sympatry, for example all three African species (P. bispina, P. infuscata and P. munroi) have been collected in the Noordkaap River area (Mpumalanga province) by Miller in lush, damp grassy drainage lines, and the two Malagasy species (P. lalitra and P. talea) have both been collected at Andasibe (Périnet).
The phenology of the species with sufficient specimens (P. bispina, P. infuscata, P. munroi) shows that there is no seasonality to their flight period, and specimens of all of these species have been collected throughout the year, even at the height of the austral winter.