Gomphus simillimus
Gomphus simillimus Selys, 1840
Local names: Yellow clubtail, Gelbe Keiljungfer, Gele rombout, Gomphe semblable
Species Information
Description
A bright yellow clubtail with black markings. It can be recognised from the others in the same genus, by the antehumeral stripes which are narrower or as wide as the adjacent black lines. On the thorax, the metapleural line is forked, unlike Stylurus flavipes. All segments of the upper side of the abdomen are crossed by a yellow line that in males widens at S8-S9. The legs are black with yellow lines on the tibiae and femura. Eyes are, as on all gomphids, wide apart and are blue or greenish.
G. simillimus is very average in size, shape and colour. Co-occuring Gomphus species are excluded as follows;
- G. vulgatissimus lacks yellow lines on legs and central line on S8-S9. Mature males are greenish with green eyes.
- G. pulchellus is paler and duller, scarcely club-tailed and the black line in front of the metastigma is not dead-ended, but extending towards the forewing base.
- Stylurus flavipes has a pair of black-encircled stripes on the front of the thorax and the black stripe behind the metastigma is not forked.
- G. graslinii has forked male appendages and thicker black markings on the thorax.
- G. lucasii may overlap in Morocco or Algeria. It is almost identical to G. simillimus and cen be distinguished with certainty only by hand characters.
As in all gomphids black markings are reduced in hot, arid areas. The Mahgrebian subspecies maroccanus is paler (distinct but also variable).
Size
Habitat
Gomphus simillimus breeds mainly in large slow-flowing rivers and to lesser degree in streams. It is found more rarely in canals and oxbow lakes and ponds fed by ground water., where it can, however, reach high densities. Reproduction has also been noted from standing waters such as abandoned gravel pits and Lake Constance (Bodensee). It is restricted to the lowlands and is rarely seen above 500 m.
Distribution
Gomphus simillimus is endemic to western Europe and the Mahgreb, with its core range in the west Mediterranean. The nominotypical subspecies is endemic to Europe while the distinct but variable Mahgrebian subspecies G. s. maroccanus is restricted to Morocco and the north-west of Algeria. In Europe the species ranges from the south of the Iberian Peninsula to north-east France. Five records from Belgium are considered vagrants. The eastermost populations are from the upper Rhine River around the border of Germany and Switzerland. The highest density of populations are found in south-western half of France, where the species is rather common. In other parts of France it is rarer, with a more scattered distribution. It is generally rather rare in the Iberian Peninsula, although slightly less so in the north-east, and in most areas it is only known from scattered populations.
Flight Period
May to July
Conservation Status
Similar Species
Gomphus vulgatissimus, Gomphus pulchellus, Gomphus graslinii, Gomphus lucasii, Stylurus flavipes
External Links
Genus: Gomphus
Gomphus is a genus of clubtail dragonflies in the family Gomphidae. As a result of phylogenetic studies, Gomphus subgenera Gomphurus, Hylogomphus, Phanogomphus, and Stenogomphurus were elevated in rank to genus in 2017. With the removal of their member species, Gomphus ended up with 11 of its previous 54 species.
Identification
Medium-sized dragonflies with a yellow to greenish body, with black markings. They have a diagnostic yellow line, almost uninterrupted, running from S1 to S7, or even S10. Eyes are clearly separated. The abdomen is club-shaped in most species, but lacks any leaf-like lateral flaps. The males have rather short, clearly diverging, upper appendages. The size is about equal to S10. The lower appendages are only slightly shorter, and their branches are largely eclipsed by the uppers when viewed from above. These short, splayed, eclipsing appendages are unique in Europe. The hindwing lacks an anal loop, therefore an uninterrupted perpendicular vein connects the subtriangle and the hind margin.
Separation from other genera
All gomphids in Europe are rather similar in general appearance and size, except for the large Lindenia and small Paragomphus. Males of both these genera bear abdominal flaps and have very long, parallel upper appendages. Ophiogomphus and Onychogomphus have an hind wing anal loop, and incurved upper appendages that do not eclipse the parallel branches of the lower appendage. Moreover, the Onychogomphus male appendages are long and pincer-like. Their abdomen appears ringed or spotted, rather than striped. In the field, confusion with Ophiogomphus is most likely, but mature adults are unmistakable because of their bright green head and thorax, as well as the yellow upper appendages.
When seen poorly, particularly in flight, females and immatures of some libellulids, particularly Orthetrum cancellatum, might resemble Gomphus. These have their eyes touching each other.
Separation of the species
Few of the genera of Europe seem as uniform as this one, and all nine species may be confused. The separation of three species (G. schneiderii, G. ubadschii, G. lucash) from their more widespread counterparts (G. vulgatissimus, G. simillimus) is still somewhat questionable, although the species in each pair are geographically (largely) separated.
Behaviour
Relatively shy dragonflies. The large numbers of exuviae found on river banks may correlate poorly to the occasional adult seen at the same site. After emerging, adults leave the water to mature in surrounding terrain, such as overgrown fields, borders and fallow land. These are often better places to search than the waterside. Mature males perch on twigs or rocks at the water's edge, waiting for females. At larger rivers they may also fly for long periods in midstream (G. vulgatissimus), or search the edges (G. pulchellus). It might be useful to search for individuals in the middle of the stream with binoculars. Females are especially shy, dashing out to open water, often in the centre of a stream, depositing many eggs in only one or several dips.
Family: Gomphidae
The Gomphidae are a family of dragonflies commonly referred to as clubtails or club-tailed dragonflies. The family contains about 90 genera and 900 species found across Europe, Asia, North and South America and Australia. The name refers to the club-like widening of the end of the abdomen (S7-S9). However, this club is usually less pronounced in females and is entirely absent in some species.
Characteristics
Clubtails have small, widely separated compound eyes, a trait they share with the Petaluridae and with damselflies. The eyes are blue, turquoise, or green. The thorax in most species is pale with dark stripes, and the pattern of the stripes is often diagnostic. They lack the bright metallic colors of many dragonfly groups and are mostly cryptically colored to avoid detection and little difference between the sexes is seen. Adults are usually from 40 to 70 mm in length.
Clubtails are fast-flying dragonflies with short flight seasons. They spend much time at rest, perching in a suitable position to dart forth to prey on flying insects. They tend to perch on the ground or on leaves with the abdomen sloping up and its tip curling down a little. Larger species may perch with a drooping abdomen or lie flat on a leaf. Another stance adopted by clubtails perching in the open is obelisking, standing with the abdomen raised vertically, a posture adopted otherwise only by the skimmers.
Most clubtails breed in streams, rivers, or lakes. The nymphs are unusual in having a flat mentum, part of the mouthparts, and their antennae have only four segments. They burrow in the sediment at the bottom of the water body.