Ruddy Darter
Sympetrum sanguineum (Mller, 1764)

Family: Libellulidae - Darters, Skimmers and Chasers

Order: Odonata (Epiprocta) - Dragonflies

Class: Insecta

Phylum: Arthropoda

Kingdom: Animalia

Red List status: Least Concern

Total length: 34-39 mm

Abdomen length: 20-26 mm

Hindwing length: 23-31 mm

Larval body length: 15-17 mm

DESCRIPTION

Adult: A relatively small, typical dragonfly. The male's dark red abdomen has a slightly, but distinctly, clubbed appearance. There is a small, distinct yellow patch at the base of the hindwing, though individuals from Turkey sometimes show extensive yellow markings on the wings. The mature male has a red face. The legs are black, without any markings. In both sexes, the thorax is unmarked, being a uniform brownish in the male. The female is yellow all over; immature males are yellow-orange. Black central markings are present on the final abdominal segments, and the underside of the abdomen has a black margin. In females, black marks are also present along the side of each abdominal segment; if present in males, these are less extensive. The pterostigma is red.

 

Male ruddy darter. Note the unmarked thorax.

Larva: Small, fairly squat, oval-shaped dragonfly larva with large bulging eyes; the front of the labial mask is typically spotted. The hind legs are very long, stretching beyond the end of the abdomen. The main diagnostic feature is the length of the spines on abdominal segment 9, which are the same length as or slightly shorter than the segment. Colouration is highly variable on both upper and undersides.

Similar species: The ruddy darter shares its range with a number of similar, related species. Small body size and a red abdomen distinguish these species from most other darter genera. The ruddy darter's unmarked black legs distinguish it from common darter (Sympetrum striolatum) and yellow-winged darter (S. flaveolum), which have a yellow stripe down the full length of each leg, and larger Crocothemis species, whose legs are never black. The wings are dark-veined, a feature which reliably distinguishes it from red-veined dropwings (Trithemis). Other genera with yellow females have broader abdomens, and black patterning is often more extensive.

S. sanguineum males are a deeper red than other European Sympetrum species, with a more strongly clubbed abdomen. The ruddy darter is the commonest black-legged species in much of its range. The clear wings with yellow only at the base distinguishes the species from banded darter (S. pedemontanum), which has prominent brown bands, and from species with either no or extensive yellow marking. Red-veined darter (S. fonscolombii) has a distinctive blue underside to the eyes (greenish in S. sanguineum), a paler pterostigma, and typically reddish wing veins. The remaining species, the spotted darter (S. depressiculum), has a flattened, broad abdomen marked with two rows of black spots along the dorsal surface (not along the flank, as in S. sanguineum) in both sexes, and less distinct central markings on the final abdominal segments.

The larval form is similar to that of related species. The presence of spines at the sides of body segments 8 and 9 (the final segments before the tail) distinguish it from species other than the common darter, and the most reliable way to distinguish between the two is to identify adult stages from the same waterbody. Ruddy darters often prefer established, well-vegetated and sometimes seasonal waterbodies while common darters may colonise newly-created pools. In the absence of this information, the spines on segment 9 is usually shorter than the length of the segment in the ruddy darter (longer in common darter), but differences can be small and none of these features can be regarded as 100% reliable in distinguishing the two species.

 

HABITAT

Varied, but with a preference for still, often nutrient-rich waters with extensive marshy vegetation. It may also occur in large, woodland pools exposed to sunlight. The ruddy darter typically avoids streams and acidic waterbodies. Preferred sites are often shallow, and may either be late-successional permanent ponds or temporary pools that fish are unable to colonise. In the latter, the ruddy darter will often be the only dragonfly present, although it is commonly found in association with emerald damselflies (Lestes). Larvae are most commonly encountered in areas of thick emergent vegetation.

Reproductive habitat: Females oviposit into mud, stands of dense vegetation and other terrestrial situations at the water's edge, areas where springtime immersion will prompt hatching.

 

BEHAVIOUR

In common with other darters, common darters select prominent perches, typically on waterside vegetation, from which to launch sorties to capture prey or deter others. Males often occur in high densities around the water's edge and defend their immediate area from rivals, although they do not protect fixed territories.

Diet: Dragonflies are typically opportunistic predators; adults capture food on the wing, and may do so at a faster rate than they can consume prey items. Ruddy darters have been observed to hoard up to eight fruit flies at a time in their mouthparts (Corbet & Brooks, 2008).

Breeding behaviour: Mating begins in tandem, in which the male clasps the female behind the head and the two pair flies in this position, one dragonfly behind the other. Animals may also fly in the 'mating wheel' position, in which reproduction takes place. Animals may then disengage, with the female continuing to lay eggs as the male guards her, although females ovipositing alone typically lay fewer eggs than the same individual in tandem (Corbet & Brooks, 2008).

Emergence: Larvae emerge onto aquatic vegetation, generally low in the water. Emergence typically peaks between late June and late July in northern areas such as the United Kingdom, where the emergence period can extend from mid-May to September.

Flight season: In northern areas, the flight season can extend from June into November, being most abundant in August. At the southern extent of the species' range, in Turkey and North Africa, adults may be encountered as early as April.

 

BIOLOGY

Life cycle: In common with the common darter, the ruddy darter exhibits the unusual ability to facultatively delay development of its eggs or undergo immediate direct development, presumably as a response to different environmental conditions (Corbet & Brooks, 2008). Most other dragonfly species undergo either direct or delayed development. Direct developing individuals take a full year to complete development. Overwintering eggs may hatch into larvae that are able to complete development and leave the water later in the same year, allowing the species to make use of ephemeral waterbodies.

 

TAXONOMY

An eastern form sometimes considered subspecies S. s. armeniacum exhibits yellow streaks on the femur; however the tibia remains all black.

 

STATUS

 

Although common throughout its range, the ruddy darter may be at risk from crop production and associated water pollution. No conservation measures exist for this species, and population monitoring schemes are in progress.

 

REFERENCES

 

Clausnitzer, V. 2007. Sympetrum sanguineum. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1

Corbet, P. and Brooks, S. 2008 Dragonflies New Naturalist Series 106, Harper-Collins, London: 456pp

Dijkstra, K-D.B. and Lewington, R. 2006 Field Guide to the Dragonflies of Britain and Europe British Wildlife Publishing: 320 pp

Cham, S. 2007 Field Guide to the larvae and exuviae of British Dragonflies Volume 1: Dragonflies (Anisopera) The British Dragonfly Society: 76 pp.

Male Sympetrum sanguineum. Buckinghamshire, UK. Note the lateral black abdomen markings in this specimen

Male ruddy darter. Epping Forest, Essex, United Kingdom. Note the clubbed tail and the yellow hindwing base.
RANGE

Almost Europe-wide, east to Siberia. In Europe, it is absent from the Alps. The species has a scattered, disjunct distribution in south and central regions of the Iberian Peninsula and adjacent areas of coastal North Africa. The species is absent from northern Scandinavia, much of Wales and northern Britain, but is expanding its range northwards and westwards in the UK and has recently been recorded in Scotland. It occurs throughout Ireland, but is localised or absent from some smaller European islands. Its presence on Sardinia is unconfirmed.

Range        Description        Habitat        Behaviour        Biology        Taxonomy        Status        References