Species recognition trade-off between structural wing colours and terminalia in fungus gnats ?
J. Kjaerandsen Museum of Zoology Lund University Sweden Structural colours in flies Reflective scales in Diptera – Mosquitoes: Toxorhynchites manicatus (Japan) Reflective body scales in fungus gnats – only in the genus Allactoneura ? Hymenoptera: Eulophidae
PhD student Ekaterina Shevtsova Wings imbedded in a medium or studied on a white background will not display their structural colours
Slide with wings embedded in Canada balsam
Dry specimens studied on a pure white background Mycetophilidae: Rymosia fasciata
Keroplatidae: Proceroplatus scalprifera
WIPs — Wing Interference Patterns
i for interference
Bolitophila occlusa Hybotidae: Ocydromia glabricula
Cordyla sp. (California) Exechia nugatoria Photo: “Klaas” at Diptera.info, 2008 (= nigroscutellata) (California) Photos: Peter Kerr, 2008
My photo of the same species’ WIP Photos of structural wing colours on internet WIPs — Wing Interference Patterns i for interference
• — Genetics of pigment patterns • — Thin Film Interference • — Newton Scale Metering
• — Exechiini
• — Lygistorrhinidae
• — Keroplatidae
• — The trade-off Pigmentation in brown, yellow and black: Spatiotemporally regulated by yellow and ebony
MELANINS
Leia Proceroplatus (Japan) (New Caledonia)
Scientists unlock mystery of animal colour patterns
Genetic April 22 control of pigment 2010 patterns
T. Werner, S. Koshikawa, T. M. Williams, S. B. Carroll, Nature 464, 1143 (2010) Pigments are only a part of the ”mystery of wing colour patterns”!
Holotype wing of Drosophila guttifera — described in 1849! Thin Film Interference
I R I D E S C E N C E Thin Film Interference
Thin Thick
Chloropsina sp. (Malaysia) • only ≈ 20% of the light is reflected Microstructures stabilize the colours! HYMENOPTERA (Chalcidoids) DIPTERA (Drosophila)
SEM
DUO- TONE
WIP Newton Series Scale Metering Mycetophilidae: Greenomyia mongolica (Hungary)
1500
1250 nanometers in thickness wing
1000
750
WL ≈ 3.2 mm 500 This Greenomyia species display a uniform 400 gradient from 300 nm to 1000 nm that is hardly affected by its venation 250 & a rather smooth membrane
0 Newton Series Scale Metering Mycetophilidae: Exechia festiva (Norway)
1500
1250 nanometers in thickness wing
1000
750
500 WL ≈ 4 mm
This Exechia species display a radial gradient 250 from 250 nm to 600 nm & a strongly micro-structured membrane 0 Newton Series Scale Metering Pachyneuridae: Pachyneura oculata (Russia)
1500
1250 nanometers in thickness wing
1000
WL ≈ 8.5 mm 750
This Pachyneura species has has 500 a thickened caudal wing rim, about 400 nm and seen as a green line and thinnest wing membrane in the 250 anal sector 0 Newton Series Scale Metering Synneuridae: Synneuron annulipes (Sweden)
1500
1250 nanometers in thickness wing
1000
750 WL ≈ 3.2 mm
This Synneuron species has thickened 500 wing rim of ≈ 350 nm and a steep linear gradient from 300 to 600 nm in 250 R-sector
0 The new habitus standard?
Rymosia triangularis Shaw, 1935
Holotype, male from New Betlehem, New York — collected in 1934 Variation in WIPs in the tribe Exechiini
5 male and 5 female wings of Rymosia fasciata Exechia festiva ≈ 4 mm arranged according to 30% size variation:
4.5 mm
Exechiopsis hammi ≈ 3.8 mm
Tarnania nemoralis ≈ 4.5 mm
Myrosia maculosa ≈ 5 mm
3.15 mm Morphometric variation in genus Pseudexechia Gonostyles variation in genus Pseudexechia
?
? ?
? DIPTERA, Mycetophilidae Manota indahae (Japan)
WL ≈ 2.12 mm Bibionomorpha, various families
Pachyneura oculata (Russia) 8.5mm Macrocera fascipennis (Sweden) 5.5mm
Aphioletes aphidimyza (Sweden) Lygistorrhina borkenti (Honduras) 3mm
Bolitophila maculipennis (Sweden) 7.5mm Exechia festiva (Norway) 4 mm Lygistorrhinidae
Lygistorrhinia pictipennis (Japan) Lygistorrhinia borkenti (Honduras)
Lygistorrhinia sp. (South Africa) Lygistorrhinia caryoni (New Caledonia)
Lygistorrhinia hamoni (Ghana) Seguyola variegata (Ghana)
Lygistorrhinidae Lygistorrhina pictipennis (Japan)
WL ≈ 3.02 mm
WL ≈ 2.73 mm Lygistorrhinidae Lygistorrhina pictipennis (Japan)
Complete M-fork !
WL ≈ 3 mm Keroplatidae Proceroplatus spp.
Proceroplatus sp. (Honduras)
Proceroplatus scalprifera (New Caledonia) Keroplatidae Proceroplatus sp. (Honduras)
WL ≈ 3.5 mm Keroplatidae Macrocera fascipennis (Sweden)
WL ≈ 5.5 mm Keroplatidae Macrocera grandis (Sweden)
WL ≈ 8.5 mm Keroplatidae Macrocera angulata (Sweden)
WL ≈ 5.0 mm Sciaridae Zygoneura sp. (Japan)
WL ≈ 2.4 mm DIPTERA, INCERTAE SEDIS Sciarosoma borealis (Sweden) Diadocidiidae Didaocidia ferruginosa (Sweden) Cecidomyiidae Aphioletes aphidimyza (Sweden)
Species recognition trade-off between structural wing colours and terminalia in fungus gnats ?
• This first taxonomic sweep indicate a trade-off between species- specific terminalia and species-specific WIPs.
• The tribe Exechiini (Mycetophilidae) largely reveal rather uniform WIPs that merely reflect size dependant radial gradients. – Taxa with enlarged, elaborate terminalia (often more advanced/recent groups) tend to have less species-specific WIPs.
• Lygistorrhinidae and some Keroplatidae (Macrocera ++) reveal striking examples of what appears to be species-specific WIPs – Taxa with less species-specific terminalia (often more primitive groups) tend to have elaborate WIPs including pigmentations
• Important questions for further studies: – How much intraspecific variation? – Slight change of colour when insect die and wing dry up – Do fungus gnats insects really see and use these WIPs?
SPECIAL THANKS TO:
•Ekaterina Shevtsova & Christer Hansson
•The Swedish Taxonomy Initiative
• Prof. Dietrich Zawischa (Univ. Hannover)