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Onychogomphus forcipatus (Small Pincertail, Green-eyed Hooktail / Küçük Kerpetenkuyruklu Yusufçuk, Yeşilgözlü Çengelkuyruk)

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Onychogomphus forcipatus (Small Pincertail, Green-eyed Hooktail / Küçük Kerpetenkuyruklu Yusufçuk, Yeşilgözlü Çengelkuyruk)


Onychogomphus forcipatus (Small Pincertail, Green-eyed Hooktail / Küçük Kerpetenkuyruklu Yusufçuk, Yeşilgözlü Çengelkuyruk) [Female/Dişi] from Ünye, Ordu- 25.07.2009.

The Small Pincertail is indeed marginally smaller than its stable mate the Large Pincertail (Onychogomphus uncatus). More importantly, though, Onychogomphus forcipatus is very much the more common and widespread species of the two. Its range extends from Southern Scandinavia all the way down to the Mediterranean, although the species is absent from the British Isles. At any type of running water here in Italy it's quite common to see a male Small Pincertail perched on a rock in the so-called obelisk position. The species' most distinguishing features include its grey-to-green eyes (as opposed to O. uncatus's blue eyes), and the relatively narrow, wavy black stripes on the side of the thorax, the first of which meets up with the dark dorsal stripe.

Small Pincertail is an medium-sized anisopteran that is about as large as Southern Skimmer with a total length of 46-50mm (Abdomen length: 31-37mm, with a hind wing spans of 25-30mm). It is the only Onychogomphus that can have dark (not yellow) upper appendages and green eyes (without a hint of blue). Unfortunately, the species is variable and these characters usually do not apply in Mediterranean countries where O. forcipatus overlaps with its congeners. In Turkey, O. flexuosus and O. macrodon are much paler, with a “double-ringed” abdomen and pale pterostigma, while O. assimilis has clearly different thorax pattern. O. lefebvrii can best be separated in the hand, but hardly overlaps. In SW Europe and NW Africa, O. costae is almost devoid of black, while O. uncatus differs mainly in detail of thorax.

Upper and lower appendages are similar length. Lower has two small dorsal tooth-like knobs at the base, as wellas a dorsal knob near the tip. The subbasal knobs are shared only with O. uncatus. The subterminal knobs are unique, their shape defining the subspecies. The uppers typically overlap at their tips, each bears a thumb-like dorsal lobe, lying just past the appendage’s bending point (visible from above or behind). The females has a small but distinct yellow(-tipped) tubercle behind each eye. Other than the less-developed tubercles in O. lefebvrii, these are unique.

The three subspecies were long separated by colouration, but this is unreliable. Compared with ssp. forcipatus, the southern ssp. unguiculatus and albotibialis have less black (e.g. usually more yellow on thorax and upper appendages) and the eyes are more blue-green than green.

The species common in the south, but local in the north, extending to the Urals. It prefers largely unshaded (usually rocky) rivers and streams. Occasionally occurs at large lakes. It flights from May to September.

References: 1. Chinery, M. (1986). Collins Guide to the Insects of Britain and Western Europe, Collins, Glasgow, 320 pp. 2. Dijkstra K.-D. (2006). Field Guide to the Dragonflies of Britain and Europe including Western Turkey and noth-Western Africa. British Wildlife Publishing, Dorset, UK. 320 pp. 3. Beaton, G. (2007). Dragonflies and Damselflies of Georgia and the Soustheast. University of Georgia Press, Athens, Georgia, 355 pp.

Author Bayram GÖÇMEN
Created on Saturday 25 July 2009
Posted on Thursday 14 July 2011
Tags Ordu, TURKEY / TÜRKİYE
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