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Platystomatidae (Signal flies)

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Platystomatidae (Signal flies) is a distinctive family of flies (Diptera), worldwide in distribution predominating in the tropics. It is one of the larger families of acalyptrate Diptera with around 1200 species in 119 genera.

Signal flies are very variable in external appearance, ranging from small (2.5 mm), slender species to large (20 mm), robust individuals, often with body colours having a distinctive metallic luster and with face and wings usually patterned with dark spots or bands.

Many bizarre forms of morphology occur in this family. Heads and legs (fore legs especially) may be oddly shaped, extended in various ways or with adornments, all of which serve to supplement agonistic behaviour. Such behaviour underlies social and sexual interaction between individuals of the same species of Signal flies.

Adults are frequently found on tree trunks and foliage and are attracted to flowers, decaying fruit, excrement, sweat, and decomposing snails. Larvae are found on fresh and in decaying vegetation, carrion, human corpses, and root nodules. Most larvae are either phytophagous (eating plant material) or saprophagous (eating decomposing organic matter). Some are predatory on other insects and others have been found in human lesions, while others are of minor agricultural significance.

The species of this family are frequently mixed with unsorted specimens of higher Tephritoidea: Tephritidae, Ulidiidae and Pyrgotidae - see the diagnosis for full details.

Platystomatidae (signal flies)

provided by EOL authors
Body length 3.25-12 mm (World fauna: 2.5-20 mm) and form ranging from small, slender species to large, robust individuals. Body colors often with a metallic luster and wings usually patterned with dark spots or bands.

Head exhibits range of morphological variation, with either frons and face bulging forwards or gena swollen and extending backwards. Head higher than long; ocelli present; lower frontal setae absent, one or two reclinate orbital setae; inner and outer verticals present; genal seta present; vibrissa absent to rudimentary; postocellar setae weak, divergent. Pedicel with dorsal seam, first flagellomere elongate, sometimes with apical point; arista finely setose to pubescent. Proboscis stout, palpus flattened.

Thorax longer than broad; setae present (one pair of each, unless stated): postpronotal, 2 pairs notopleural; anepisternal; postsutural supra-alar; postalar; intra-alar; prescutellar acrostichal; prescutellar dorsocentral; basal (sometimes), lateral and apical scutellar.

Wing usually with pigmented pattern; humeral costa break present; R1 and R4+5 dorsally setulose for almost entire length; cup subrectangular at apex – CuA2 perpendicular to Cu at its base and either straight or convexly curved toward middle.

Legs moderately developed, sometimes with armature, especially on the forelegs when present.

Abdomen subcylindrical to narrow-ovate. Male postabdomen with sternite 6 reduced or absent; strongly sclerotized bilobed cap on ejaculatory apodeme; phallapodeme present; well developed inner surstyli. Female postabdomen with segment 6 reduced or absent; segment 7 present as conical oviscape, which forms rigid base to flattened ovipositor sheath protecting retractable (by invagination) segment 8 or aculeus, with apical sensory setae on either side. Larvae with generalized, subcylindrical schizophoran morphology, typical of many Tephritoidea.

Identification:
The species of this family are frequently mixed with unsorted specimens of higher Tephritoidea. The absence of frontal setae, the lack of any extension of the posterior apex of cup and the presence of setulae along the whole length of R1 (and frequently all of R4+5) distinguishes Platystomatidae from most Tephritidae, Ulidiidae and Pyrgotidae.

Furthermore, Tephritidae have between one and five frontal setae and a subcostal break.

In Ulidiidae, postocellar setae are better developed, katepisternal setae present, and the coiled aedeagus lacks a distinct apical glans.

Pyrgotidae often have a proepisternal ridge bearing strong setae (absent in all Platystomatidae) and lack ocelli.

Platystomatidae

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Strange courtship behaviour of the European signal fly Platystoma seminationis (video, 7m 19s)

The Platystomatidae (signal flies) are a distinctive family of flies (Diptera) in the superfamily Tephritoidea.

Signal flies are worldwide in distribution, found in all the ecozones, but predominate in the tropics. It is one of the larger families of acalyptrate Diptera with around 1200 species in 119 genera.

Biology

Adults are found on tree trunks and foliage and are attracted to flowers, decaying fruit, excrement, sweat, and decomposing snails. Larvae are found on fresh and decaying vegetation, carrion, human corpses, and root nodules. Most larvae are either phytophagous (eating plant material) or saprophagous (eating decomposing organic matter). Some are predatory on other insects and others have been found in human lesions, while others are of minor agricultural significance.

Family description

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Australian species - about 7 mm in length

For terms see Morphology of Diptera
Signal flies are very variable in external appearance, ranging from small (2.5 mm), slender species to large (20 mm), robust individuals, often with body colours having a distinctive metallic lustre and with face and wings usually patterned with dark spots or bands.The head is large. Frontal bristles on head are absent. Two orbital bristles are on the head. The frontal stripe is pubescent and the arista is more or less long and pubescent. The antenna1 grooves are deep and divided by a median keel. Radial vein 4+5 bears bristles. The costa is without interruptions and the anal cell is elongated, bordered on outer side by an arcuate or straight vein. The abdomen of male has five visible segments and the female has six.

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Pogonortalis doclea
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Peltacanthina species

Many bizarre forms of morphology and behaviour occur in this family. Heads and legs (fore legs especially) may be oddly shaped, extended in various ways or with adornments, all of which serve to supplement agonistic behaviour. Such behaviour underlies social and sexual interaction between individuals of the same species of signal flies, first researched in Australian species of the genera Euprosopia image and Pogonortalis[2]

In males of Pogonortalis, the length and degree of development of hairs (setae) on the lower facial area, together with widening of the head, facilitates territorial dominance[3] by head-butting and rearing-up behaviours. Head-butting is taken to the extreme in the Australasian genus Achias,[4][5] in which species have the fronto-orbital plates expanded laterally to produce eyestalks.

Development of body structures is prevalent in the Afrotropical and Oriental subfamily Plastotephritinae,[6] including 9 different types of modification in 16 genera.[7]

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Plate from Novitates Zoologicae showing the great variation in eyestalk development in Achias rothschildi
Plate from Revue et Magasin de Zoologie depicting Pterogenia singularis Bigot, 1859

Some species have prominent eyestalks also found in the family Diopsidae. In the Diopsidae, eyestalks develop through lateral development of the frontal plate, with the result that the antennae are situated on the stalk near the compound eye. The process of development in signal flies is different in that the fronto-orbital plates expanded laterally to produce eyestalks and consequently the antennae remain in a central position. This is an example of convergent evolution. The development of eyestalks reaches its extreme in the platystomatid species Achias rothschildi Austen, 1910 from New Guinea, pictured here in which males have an eye-span up to 55 mm.[8]

Families of acalyptrate flies exhibiting morphological development associated with agonistic behaviour include: Clusiidae, Diopsidae, Drosophilidae, Platystomatidae, Tephritidae, and Ulidiidae.

See also [1]

Other

Adults are sometimes amongst the most morphologically bizarre forms of all the Diptera.[2]

See also

References

  1. ^ Biolib
  2. ^ McAlpine, D.K.1973. Observations on sexual behaviour in some Australian Platystomatidae (Diptera, Schizophora). Records of the Australian Museum 29(1): 1-10.
  3. ^ McAlpine, D.K.1975. Combat between males of Pogonortalis doclea (Diptera, Platystomatidae) and its relation to structural modification. Australian Entomological Magazine 2(5): 104-107.
  4. ^ McAlpine, D.K.1979. Agonistic behavior in Achias australis (Diptera, Platystomatidae) and the significance of eyestalks. In: Blum, M. S. and Blum, N. A. (eds). Sexual selection and reproductive competition in insects. Academic Press, New York.
  5. ^ McAlpine, D.K.1994. Review of the species of Achias (Diptera: Platystomatidae). Invert. Taxon. 8(1): 117-281.
  6. ^ Whittington, A.E. 2003. Taxonomic revision of the Afrotropical Plastotephritinae (Diptera; Platystomatidae). Studia dipterologica Supplement 12: 1-300.
  7. ^ Whittington, A.E. 2006. Extreme head morphology in Plastotephritinae (Diptera, Platystomatidae), with a proposition of classification of head structures in Acalyptrate Diptera. Instrumenta Biodiversitatis VII: 61-83.
  8. ^ Arnauld, P. H. Jr. 1994. Frontispieces: Achias rothschildi Austen (Diptera: Platystomatidae). Myia 5: iv.

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Platystomatidae: Brief Summary

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File:Platystoma seminationis copula lang.ogvPlay media Strange courtship behaviour of the European signal fly Platystoma seminationis (video, 7m 19s)

The Platystomatidae (signal flies) are a distinctive family of flies (Diptera) in the superfamily Tephritoidea.

Signal flies are worldwide in distribution, found in all the ecozones, but predominate in the tropics. It is one of the larger families of acalyptrate Diptera with around 1200 species in 119 genera.

license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN