Clusia Haliday

Introduction

Plate from Handlirsch (1884) showing wings of Clusia species: C. tigrina (figure 9), C. flava (figure 10)

Clusia Haliday (which now includes Paraclusia Czerny and Amuroclusia Mamaev (Lonsdale & Marshall, 2008)) occurs in the Holarctic and Oriental Regions and is comprised of 13 species. Several of these large, showy species are quite commonly encountered in North America and Europe, and consequently, have been discussed at length in the scientific literature over the past 150 years. The family name "Clusiidae" (spelled "Clusiinae" at the time) was even derived from the genus name containing the two frequently-collected European species, C. tigrina and C. flava, by Handlirsch in 1884 (see plate from original publication to right).

Adults are often found on a wide range of deciduous tree species (observations on conifers such as pine and spruce are much less frequent), preferring either stumps or dead, bare wood on standing trunks (Rohácek, 1995; Stubbs, 1982, personal obs.). Stubbs (1982) found adults of C. tigrina most often in August and September on barkless spots of live beech trees.

European Clusia have been reared from the stumps of several deciduous species such as beech, birch and elm (Perry & Stubbs, 1978; Smith, 1950), and have occasionally been reared from conifers (Soós, 1981). North American adults have been reared from 'moist wood', 'dead Populus tremuloides' and the 'cambium of dead maple'. Smith (1950) collected puparia of Clusia flava in a dry beech stump one inch from the surface in early April (emerged towards the end of the month).

Clusia czernyi and C. lateralis are found in northeast North America and C. occidentalis is found along the west coast from British Columbia to California. Clusia tigrina and C. flava are known from Europe, but C. flava is also known from Japan and likely occurs throughout the Palaearctic. Clusia sexlineata is found in Burma and the remaining species are known only from Japan (Sueyoshi, 2006).

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Clusia lateralis (Walker) on dead wood. Northeastern North America. © Steve Marshall

Characteristics

The synapomorphies currently used to define Clusia are as follows: one pair of interfrontal bristles; two pairs of stout lateral scutellar bristles that greatly exceed the apex of the scutellum (one pair sometimes lost); arista pubescent to short-plumose (not long-plumose); cross-vein dm-cu surrounded by wide infuscation (secondarily lost in several species); scutellum with central yellow stripe (sometimes expanded to include entire scutellum); epiphallus heavily sclerotized and produced anteriorly. Putative female genitalic characters include: ventral receptacle cylindrical; spermatheca dark (usually with dark reticulated pattern) excluding a small circular region around the point of attachment to the spermathecal duct. 

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Male genitalia, head chaetotaxy, and female genitalia of Clusia czernyi. © Owen Lonsdale

Discussion of Phylogenetic Relationships

Clusia was redefined by Lonsdale & Marshall (2008) to include the Palaearctic genera Paraclusia and Amuroclusia, which are now considered junior synonyms.
The relationships between the species of Clusia are not fully resolved although the basal position of C. tigrina is fairly certain. A revision of the genus is currently being developed.

Relationship of Clusia to Other Clusiinae

Within the Clusiinae, reduced postverticals and a number of male-specific characters support a relationship between the predominantly Holarctic Clusia and the more southern Melanoclusia (Borneo) (Lonsdale & Marshall, 2008). These male characters are as follows: two rows of posteroventral bristles on the fore and mid femora (also found in the Chilean Clusiidae and Clusiodes), an inner-basal spur on a small, triangular surstylus, a uniquely-shaped pregonite (long, thin, minutely setulose along length and closely-associated with base of phallapodeme) and absence of the lateral lobes of the distiphallus (independently lost in some Sobarocephalinae and most Clusiodinae).

References

Handlirsch, A. 1884. Zwei neue Dipteren. Verhandlungen der [Kaiserlich-Königlichen] Zoologisch-Botanischen Gesellschaft in Wien 1884: 135-142.

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. Synonymy within Clusia and description of the new genus Melanoclusia (Diptera: Clusiidae: Clusiinae). Annals of the Entomological Society of America 101(2): 327-330

Sueyoshi, M. 2006. Species diversity of Japanese Clusiidae (Diptera: Acalyptrata) with description of 12 new species. -Annales de la Société Entomologique de France 42(1): 1-26; Paris.

Rohácek, J. 1995. Clusiidae (Diptera) of the Czech and Slovak Republics: Faunistics and notes on biology and behaviour. Cas. Slez. Muz. Opava (A) 44: 123-140.

Stubbs, A.E. 1982. An identification guide to British Clusiidae. Proceedings of the Transactions of the British Entomological Natural History Society 15: 89-93.

Perry, I. & A.E. Stubbs. 1978. Dead wood and Sap runs. A Dipterist's Handbook 15: 65-73.

Smith, K.G.V. 1950. The puparium of Clusia flava Mg. (Diptera: Clusiidae). The Entomologist's Monthly Magazine 86:53.