Apiochaeta

Introduction

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Apiochaeta Czerny wings: A. philippi (Rondani); A. pictipennis (Wulp); A. chiloensis (Malloch); A. vitticollis (Blanchard); A. excepta (Malloch); A. varia (Malloch); A. costalis (Malloch)

The 16 species of this genus were revised by Lonsdale & Marshall (2008), who redefined the genus to include all of those species previously treated as Alloclusia Hendel, which is now considered to be a junior synonym of the senior Apiochaeta. The Chilean fauna was previously treated by Malloch in 1933, who described most of the species in the genus.

Characteristics

Apiochaeta is a distinct, large-bodied genus of flies that can be readily diagnosed by three dorsocentral bristles, an angulate cell dm, an elongate curved distiphallus with one pair of lateral spinulose projections, and a ventral receptacle with numerous transverse wrinkles and two ventral longitudinal furrows (Lonsdale & Marshall, 2008).  One pair of sister-species including Apiochaeta aequalis Malloch is characterized by a broad head, inset posterior fronto-orbital bristles and usually white notal patches; most other species like Apiochaeta pictipennis (Wulp) are large, pale, strongly striped, and often with elaborately patterned wings.

Like other Clusiinae, Apiochaeta also has an inclinate anterior fronto-orbital bristle, a small ratio of the length of the ultimate section of vein M to the penultimate, a subnotal stripe, a dorsal preapical bristle on the mid tibia, outstanding bristles on the posterodorsal surface of the fore femur, a bent or jointed distiphallus, and a posteromedial truncated notch on the vertex (Lonsdale & Marshall, 2006).

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Figure: Apiochaeta pictipennis (Wulp) male genitalia; hypandrial complex not to scale. © Owen Lonsdale.

Phylogenetics

Apiochaeta, like the Holarctic and Oriental Clusia Haliday, 1839, has an inclinate anterior fronto-orbital bristle, a presutural intra-alar bristle, an M1,2 ratio less than 2.5 (3.0 in A. bicolor (Schiner)), a fore femur with several outstanding posterodorsal bristles, three rows of ventral ctenidial bristles on the male fore and mid femora (one anterior, two posterior), a subnotal stripe, an elongate and medially bent distiphallus and a truncate notch on the posterior margin of the frons behind the ocelli.

The genus also has similarities to other taxa endemic to the Neotropics, however, and unpublished molecular evidence strongly supports its placement in the Sobarocephalinae:

Apiochaeta is also similar to Sobarocephala Czerny, 1903 and Chaetoclusia Coquillett, 1904 (which are also found in South America but do not occur in the southern temperate region) in that it has a dorsal preapical bristle on the mid tibia, a surstylus that is at least half as long as the epandrium and an enlarged ventrolateral hypandrial lobe. It differs from all of these genera, however, in that it has three pairs of well-developed dorsocentral bristles, an oblique vein dm-cu, one pair of elongate spinulose lobes fused to the base of the distiphallus, and a ventral receptacle with numerous transverse wrinkles and two ventral longitudinal furrows (Lonsdale & Marshall, 2008).

Other Names for Apiochaeta

• Alloclusia Hendel

References

Czerny, P.L. 1903. Revision der Heteroneuriden. Wiener Entomologische Zeitung 22(3): 61-108.

Lonsdale, O. & Marshall, S.A. 2006. Redefinition of the Clusiinae and Clusiodinae, description of the new subfamily Sobarocephalinae, revision of the genus Chaetoclusia and a description of Procerosoma gen. n. (Diptera: Clusiidae). European Journal of Entomology, 103: 163-182.

Lonsdale, O. & Marshall, S.A. 2008. Revision of the temperate South American genus Apiochaeta Czerny, 1903, with synonymy of Alloclusia Hendel, 1917 (Diptera: Clusiidae). Zootaxa 1944: 1-33.

Malloch, J.R. 1933. Facile 4 ? Acalyptrata [part]. The Diptera of Patagonia and South Chile. Clusiidae. Pt. VI pp. 232-245. British Museum of Natural History, London, 499pp.

Melander, A.L. & N.G. Argo. 1924. Revision of the two-winged flies of the family Clusiidae. Proceedings of the United States Natural History Museum 64: 1-54.