Paleoptera

FIGURE 6.10. Proposed phylogeny of extant Odonata.

Epiophlebioidea form the sister group to all others. Of these, the very primitive Petaluridae form the sister group to the remaining true dragonflies.

Suborder Zygoptera (Damselflies)

Damselflies are characterized by the following structural features: fore and hind wings almost identical in shape and venation, quadrangular discoidal cell never longitudinally divided, eyes far apart, and larvae with three (rarely two) caudal lamellae.

Superfamily Coenagrionoidea

Most of the 1500 species of Coenagrionoidea fall into four families. The paraphyletic family COENAGRIONIDAE is the most successful zygopteran group, containing more than 1000 species. The family as a whole is cosmopolitan, and certain genera, for example, Coenagrion and Ischnura (Figure 6.11), are found throughout the world. Larvae are found among vegetation in still or slowly moving water. The generally small adults are weak fliers and rest with their narrow wings closely apposed over the body. The sexes are differently colored, with males usually much brighter. Commonly, the dorsal surface of males is a complex pattern of pale blue and black markings. Females are usually drab in color and in some species there may be two or more color forms. Pruinescence, the development of a waxy, whitish to pale blue secretion, is seen in older specimens of both sexes in some species. PLATYCNEMIDIDAE (150 species) are common in the palearctic, oriental, and tropical African regions where they breed in swamps, forests, streams, and fast-flowing water. The PROTONEURIDAE (220 species) are a widespread group, though absent from the palearctic region. They are most common in shaded localities, including forests, and breed in slowly moving water. Most of the 130 species of PLATYSTICTIDAE are oriental though some species occur in the New World tropics. Typically, they are found in forests, breeding in fast-flowing streams.

FIGURE 6.11. A damselfly, Ischnura cervula (Coenagrionidae). (A) Adult male; and (B,C) larva, dorsal and lateral views. [Reproduced by permission of the Smithsonian Institution Press from Smithsonian Institution United States National Museum Proceedings, Volume 49, 'Notes on the life history and ecology of the dragonflies (Odonata) of Washington and Oregon,' July 28, 1915, by C. H. Kennedy: Figures 77, 120, and 121. Washington, D.C., U.S. Government Printing Office, 1916.]

FIGURE 6.11. A damselfly, Ischnura cervula (Coenagrionidae). (A) Adult male; and (B,C) larva, dorsal and lateral views. [Reproduced by permission of the Smithsonian Institution Press from Smithsonian Institution United States National Museum Proceedings, Volume 49, 'Notes on the life history and ecology of the dragonflies (Odonata) of Washington and Oregon,' July 28, 1915, by C. H. Kennedy: Figures 77, 120, and 121. Washington, D.C., U.S. Government Printing Office, 1916.]

Superfamily Lestinoidea

About three quarters of the Lestinoidea are arranged in two families, the cosmopolitan LESTIDAE (140 species) and the primarily tropical MEGAPODAGRIONIDAE (200 species). Lestids are medium-sized, metallically colored insects that typically rest with their wings partially or completely outspread. They are found near still water or quiet streams. Eggs are laid in emergent vegetation and those of temperate species often show delayed development, an adaptation to overcome adverse climatic conditions such as drought or cold. Larvae are elongate, streamlined creatures, often well camouflaged. Megapodagri-onids occur mainly in forests, breeding in streams, marshy places, and occasionally tree holes; however, some species breed in temporary swamps. Larvae are short and thick, with the caudal lamellae held horizontally, not vertically as in other Zygoptera.

Superfamily Calopterygoidea

Members of the cosmopolitan family CALOPTERYGIDAE (160 species) are medium to large, broad-winged damselflies characterized by the brilliant metallic coloring of their bodies, and, in males, the wings also. Larval Calopterygidae are found at the margins of fast-flowing water; they have relatively long and stout antennae, long spidery legs, and elongate caudal lamellae. CHLOROCYPHIDAE (120 species) are primarily restricted to tropical Africa and Asia, though there are old reports of their occurrence in northern Australia. In the larva the dorsal caudal lamella, sometimes all three lamellae, are spikelike.

Suborder Anisoptera (Dragonflies)

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