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.

Similar to species of Clusiinae, Apiochaeta (which belongs to the subfamily Sobarocephalinae (Lonsdale et al. (2010)) also has a small ratio of the length of the ultimate section of vein M to the penultimate, a subnotal stripe, outstanding bristles on the posterodorsal surface of the fore femur, a bent or jointed distiphallus (although is it not broken medially), and a posteromedial truncated notch on the vertex (Lonsdale & Marshall, 2006). It differs most obviously from these genera in having a preapical bristle on the mid tibia, three dorsocentral bristles, a large surstylus and a south temperate New World distribution.

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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.

Despite these strong morphological similarities, however, the combined morphological and molecular evidence presented in Lonsdale et al. (2010) supports this genus as basal in the Sobarocephalinae, illustrating an unusual example of morphological homoplasy. This makes additional sense biogeographically, as the redefined Sobarocephalinae now contains all endemic New World genera, and is divided between the south and north with the south temperate lineage of Apiochaeta and the tropical lineage of Sobarocephala, Chaetoclusia and Procerosoma.

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.

Lonsdale, O., Marshall, S.A., Fu, J. & Wiegmann, B. 2010. Phylogenetic analysis of the druid flies (Diptera: Schizophora: Clusiidae) based on morphological and molecular data. Insect Systematics & Evolution 41: 231-274.

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.