Procordulia grayi: Difference between revisions

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=== Population ===

=== Population ===

Due to its distribution in sparsely populated areas, the species was regarded as rare until the 1950s.<ref name=”:7″ /> ”Hemicordulia australiae”, commonly known as the Australian emerald dragonfly, is replacing ”Procordulia grayi”, but because the population is relatively stable, ”P. grayi” is still rated as “Least Concern”. <ref name=”:2″ /><ref name=”:7″ />

Due to its distribution in sparsely populated areas, the species was regarded as rare until the 1950s.<ref name=”:7″ /> ”Hemicordulia australiae”, commonly known as the Australian emerald dragonfly, is replacing ”Procordulia grayi”, but because the population is relatively stable, ”P. grayi” is still rated as “Least Concern”. <ref name=”:2″ /><ref name=”:7″ />

==References==

==References==

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{{uncategorised|date=December 2025}}

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Procordulia grayi, commonly known as the yellow-spotted dragonfly or Gray’s dragonfly,^[2] is a dragonfly that is endemic to New Zealand.^[1]

Description

P. grayi’s distinct feature is the twin lines of yellow spots along each side of the abdomen.^[3] P. grayi measures between 48 and 52 mm in length.^[4] The thorax is a dark greenish bronze, while the upper side of the abdomen are dull brown, and lighter underneath, with the yellow spot at the front edge of each segment’s side. The legs may appear blackish or tawny-red.^[4] Another characteristic of Procordulia grayi is the dorsum of the head. A setate tubercle posteromesal is found on the back edge of the eye.^[5] Its eyes, which are closely set, are green with a faint iridescent sheen.^[4]

The larvae have an abdomen that widens from the base and has stiff, pointed appendages at the end instead of caudal lamellae.^[5] The arrangement of palpal setae is another characteristic that sets P. grayi larvae apart.^[6] Once the larvae head width is greater than 1.50 mm it reaches the stage at which wing pads first became visible. Larvae have no more than four setae on the labial palps and no middorsal hooks on the abdomen.^[5]

In New Zealand journals, Procordulia grayi is sometimes referred to as large Uropetala carovei.^[6] However, it differs from Uropetala in that it is smaller and does not burrow.^[7]

Range

P. grayi is endemic to New Zealand,^[8][9] where it can be found on the southern volcanic plateau of the North Island and all over the South Island. Although there are records from Auckland, it is primarily found in the North Island south of Waikato.^[6] The upper elevation limit of P. grayi is 1,000 metres and the lower elevation limit is 0 metres above sea level.^[1] P. grayi is known for its widespread distribution with a preference for large lakes.^[10] P. grayi tends to be associated with bigger quantities of standing water^[11] and its distribution is sub-alpine.^[12] However, P. grayi cannot be fully classified as an upland species because its larvae have been found in standing waters ranging from near sea level to 960 meters.^[13]

Habitat

Procordulia grayi’s preferred habitat is shrubland and inland wetlands.^[1] P. grayi’s ideal habitat is lakes and ponds with vegetated borders.^[14] According to earlier research, standing waters seem to be the favoured larval environment.^[11][7] P. grayi larvae also are very common along the rocky shores of lakes in New Zealand such as Lake Taupo and Lake Rotoiti.^[11]

P. grayi is found in cool, slow moving waters.^[13] P. grayi survive more successfully in colder habitats compared to warmer habitats, for example in lakes and mountain streams.^[11]

Ecology

Life cycle

The P. grayi life cycle starts with the laying of eggs on vegetation close to water, such as underwater in still or slowly flowing freshwater bodies like lakes or ponds. Inside, the embryo matures and prepares to hatch into the naiad stage. At the habitats mentioned above, the hatchling naiads will be observed on submerged plants, debris, or detritus. There is a correlation between temperature and the rate of development of P. grayi eggs.^[5] P. grayi eggs do not hatch at temperatures lower than 9.5°C, and the species’ ova do not mature when exposed to temperatures as low as 8.7°C.^[5] Low temperature and underdeveloped eggs were found to be related.^[5] Because P. grayi emerges early and needs high temperatures to mature its eggs, its survival is therefore precarious.^[13]

When P. grayi emerges from the nymph stage, its reproductive organs and wings are functional. The adult is extremely mobile, feeding, mating, and dispersing, and the entire body has hardened. Around the edges of the bodies of water from where they emerge, the adult P. grayi can be seen searching the water’s surface or resting on plants in the sunlight.^[15] When P. grayi emerge, they leave their exuviae on a surface that is partially submerged in water, like a stone or a rush stem.^[11]

Phenology

Although adults of P. grayi can travel up to 5 km between feeding and breeding areas, their movement patterns are constrained, and they are classified as “not a migrant”.^[1] This indicates that they do not disperse widely.

P. grayi’s emergence peaks between late October and mid-November and concludes by late January.^[5] The range variance is caused by the temperature at which P. grayi is found in various locations. It appears that P. grayi emerges before sunrise and after twilight. The latest individual was observed leaving the emergence location at 10:45 Solar Time. By the beginning of Civil Twilight, most P. grayi were flying in temperatures as low as 10°C.^[5]

Diet and foraging

With a larval life span of 2-4 years, Procordulia grayi is a benthic invertebrate predator that has a relatively lengthy lifespan and consumes a wide range of invertebrate food.^[16]

P. grayi is a voracious predator that exhibits an intriguing hunting technique in both its adult and juvenile stages. Adults hunt on the wing, catching flying insects with their sharp eyesight and quick flight. To catch unwary prey, the naiads use a special underwater ambush technique.^[15]

P. grayi is a cannibalistic predator of lake invertebrates that mostly feeds on non-biting midge larvae (Chironomidae) and Oligochaeta worms. They also consume other damselflies (Austrolestes colensonis) and Crustacea (Cladocera, Ostracoda).^[16] Their diet also consists of larger prey, including caddisflies (Leptoceridae, Hydroptilidae), beetles (Dytiscidae), and water true bugs (Notonectidae, Corixidae).^[16]

Predators, Parasites, and Diseases

Predators of P. grayi larvae include large aquatic fauna such as frogs, toads, fish, water beetles, aquatic bugs, and other dragonfly larvae.^[15] The majority of Anguilla dieffenbachi diets comprise of snails, particularly Lymnaea, but they also consume a lot of dragonfly larvae, such as Procordulia grayi, as they migrate towards the coast.^[17]

Population

Due to its distribution in sparsely populated areas, the species was regarded as rare until the 1950s.^[1] Hemicordulia australiae, commonly known as the Australian emerald dragonfly, is replacing Procordulia grayi, but because the population is relatively stable, P. grayi is still rated as “Least Concern”. ^[4][1]

References