Overview

Comprehensive Description

Biology

Cordulegastridae consists of six genera, about 60 species in the world and in Japan two genera with four species occur. In Southeast Asia and the Far East seven species of the genus Anotogaster occur. Among them, Anotogaster sieboldii is the largest species in Japan, with a wingspan of 12-14 cm, and is familiarly called “oniyanma”. It is distributed widely from Hokkaido, Honshu of the Mainland, Shikoku, Kyushu to the Southwestern Islands. Females oviposit dynamically into the mud of streams. Larvae inhabit small streams at lowland hills and bogs. Adult flying season is from mid-June to October.

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General Description

Large dragonfly with a black body banded boldly by yellow; its compound eyes are emerald green.

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Physical Description

Diagnostic Description

Both sides of the compound eye are connected at a point on the head. Abdominal length is 60-80 mm in the male, and ` 75-85 mm in the female. The body weight is 1.6 g in the male and 2.2 g in the female, respectively. Wing loading is 60mg/cm2 in the male and 70 mg/cm2 in the female, respectively. The fat valvula (ovipositor) protrudes from the eighth abdominal segment to the out of the abdominal tip. Body length tends to be shorter in northern and higher altitude regions. The compound eyes of the species from the Amami Islands are characteristically bluish green.

Size of the final instar larva is ca. 50 mm with dark coloration. The compound eyes stick out forward and its body form is similar to that of Orthetrum albystilum speciosum.

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Ecology

Habitat

Larvae inhabit bogs and streams in lowlands and hills.

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Population Biology

Kiyoshi (2008) sequenced the COI and COII mitochondrial regions for this species. Their work suggests that two taxonomic subgroups occur within this species, distinct enough to possibly be separate species.

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Life History and Behavior

Behavior

Behaviour

Adults occur in late June and disperse from emergence locations to forests in lowland hills. They fly to and fro along the edges of forests, and often appear at hilltops in their immature stage. Mature males move to streams and patrol within the range of a certain distance for searching females. A recent study proved that such a range of patrolling is not their territory. Males regard all that flutter, flicker or rotate as females, and respond to them by chasing, hovering or circling. This tendency makes them to respond to the rotation of a fan and a disk, flickers of TV tube, or rotation of a circular saw at a lumbermill. Also it was reported that a male responded to a flickering of a short fall of the water (elevation difference: 20cm).

Their compound eyes are green and this makes them to respond to a green disk more than to those of other coloration. The larger the female is, the more it attracts the male, therefore, the female is exceptionally larger than the male in Anisoptera.

When perching the dragonfly hangs down from a branch of a tree.

The dragonfly preys insects such as moths, horseflies, hornet and cicadas.

When a male finds a female, the former pursues the latter, grasping it and copulating with it. The duration of copulation lasts about one hour. The female oviposits with its abdominal tip, dipping in to the mud of streams. Eggs hatch in a month, and larvae live in the water for ca. five years, moulting 10 times.

Body temperature of patrolling males is ca. 40 ℃, rather constant and low for their large and heavy body. The wing stroke frequency is dependent on ambient temperature and is negatively correlated with it; ca. 30-40 Hz, however, in the ovipositing female wing stroke frequency is ca. 30 Hz and has no correlation with the ambient temperature.

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Molecular Biology and Genetics

Genetics

Kiyoshi (2008) sequenced the COI and COII mitochondrial regions for this species. Their work suggests that two taxonomic subgroups occur within this species, distinct enough to possibly be separate species.

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Molecular Biology

Kiyoshi (2008) sequenced the COI and COII mitochondrial regions for this species. Their work suggests that two taxonomic subgroups occur within this species, distinct enough to possibly be separate species.

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Wikipedia

Anotogaster sieboldii

Anotogaster sieboldii or oniyanma (オニヤンマ、鬼蜻蜓、馬大頭?) in Japanese is the largest species of dragonfly native to Japan. It can grow between 95 and 100 mm in length.[1] It is also found in other parts of Asia.

Life cycle[edit]

 Anotogaster sieboldii on a twig
An Anotogaster sieboldii' or oniyanma (オニヤンマ?) seen on a twig in the Nasu Highlands of Tochigi, Japan

Eggs hatch within a month of being laid. The larvae live for three to five years, moulting as many as ten times and growing as large as five centimeters in length. Once this size, the larvae will feed on tadpoles and small fish. The adult dragonfly can mate and lay eggs within one to two months of metamorphosis. After mating, females head toward small creeks or ponds, not fast-moving rivers or lakes, to lay eggs. They will sometimes fly perpendicularly to the water, laying their eggs in mud or sand under the surface.


Notes[edit]

  1. ^ ふしぎがわかる しぜん図鑑 こんちゅう, page 35. Froebel-Kan CO., LTD., 1999

References[edit]

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