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“ Palaeoptera ”

“ Palaeoptera ”. Lecture 3. Some major characteristics of Hexapoda : Maxillary plate present 3 body parts (head, thorax, abdomen) 3 thoracic segments each bearing a pair of legs Legs composed of 6 segments 11 maximum abdominal segments Trachea Some major characteristics of Insecta :

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“ Palaeoptera ”

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  1. “Palaeoptera” Lecture3

  2. Some major characteristics of Hexapoda: • Maxillary plate present • 3 body parts (head, thorax, abdomen) • 3 thoracic segments each bearing a pair of legs • Legs composed of 6 segments • 11 maximum abdominal segments • Trachea • Some major characteristics of Insecta: • External mouthparts • Malpighian tubules • Annulated antennae • 2 pretarsal claws articulated with tarsus • Johnston’s organ • Ovipositor • Posterior tentorial arms fused

  3. Ephemeroptera(ephemera, short-lived; ptera, wings)

  4. Major characteristics • Mayflies • Common in ponds and streams • Nymphs aquatic • Wings at rest held together above the body • Small, bristle-like antennae • Front legs of male much longer than other legs • Caudal filaments on 10th abdominal segment

  5. Interesting Biology • Mating swarm • Mayflies have short adult instar period (1-2 days) • Vestigial mouthparts and no feeding • Enormous numbers in swarm (mostly males) • Females enter swarm later, mating in flight, oviposition on the surface of water

  6. Interesting Biology • Mayfly nymphs are aquatic • 12-45 instars with fully developed mandibulate mouthparts • Gills for gas exchange • Feed on algae, diatoms, aquatic fungi and detritus • Active at night • Important ecological indicators

  7. Site for gas exchange (no spiracle, closed tracheal system)

  8. Interesting Biology • Emerges as a subimago • Shorter legs and caudal filaments, wings translucent • Flies off and molts again to the imago • Only known example of fully winged insects undergoing a molt

  9. Diversity • 37 extant families, ~3000 species worldwide • Classification unstable • McCafferty and Edmunds (1979): Schistonota and Pannota • McCafferty (1991): Pisciforma, Setisura, and Retracheata • McCafferty and Kluge (2004): Carapacea, Furcatergalia, Setisura, and Pisciforma

  10. Phylogeny of Ephemeroptera based on DNA (Ogden and Whiting 2005) • Most suborders are not monophyletic • Some families are not monophyletic • Classification still unstable

  11. Common Florida mayflies • Florida has 15 families of mayflies • Important characters: wing venation and tarsal segments

  12. Common Florida mayflies • Baetidae • Largest family of mayflies (in numbers) • Adults small (front wings 2-12mm) • Hind wings small or absent • Two caudal filaments in adults

  13. Common Florida mayflies • Heptageniidae • Second largest family • Nymphs head and body flattened • Nymphs found underside of stones in streams • Adults have two caudal filaments and two pairs of cubitalintercalaries that are parallel • Hind tarsi five-segmented

  14. Odonata(odon, meaning tooth [referring to the teeth on the mandibles])

  15. Major characteristics • Mobile head with large compound eyes and three ocelli • Short bristle-like antennae • Mandibulate mouthparts • Four wings elongate, many-veined, membranous • Males have secondary genitalia • Nymphs aquatic with up to 20 instars • Predaceous

  16. Interesting biology • Modified labium for capturing prey

  17. Gas exchange using gills • Damselfly nymphs have elongate tracheal gills (caudal lamellae)

  18. Gas exchange using gills • Dragonfly nymphs have the branchial chamber modified from rectum

  19. Diversity • 34 extant families, ~6000 species • Two suborders: Zygoptera and Epiprocta • Many fossils (oldest known from Carboniferous) Meganeurafrom the Carboniferous

  20. Phylogeny of Odonata based on DNA, morphology, fossils (Bybee et al. 2008, Cladistics) • Two monophyletic suborders: Zygoptera and Epiprocta • Many families not monophyletic • Epiprocta = Epiophlebiidae + Anisoptera

  21. Common odonates of Florida • Aeshnidae • Darners • Largest and most powerful

  22. Common odonates of Florida • Libellulidae • Common skimmers • Common in ponds and swamps

  23. Common odonates of Florida • Coenagrionidae • Narrow-winged damselflies • Large family with many genera and species • Variety of habitats

  24. “Palaeoptera” problem • Ephemeroptera and Odonata are commonly called “Palaeoptera” meaning ancient wings (non-folding), in contrast to “Neoptera” meaning new wings (folding) • The relationships among Ephemeroptera, Odonata, and Neoptera have not been fully resolved.

  25. Three phylogenetic hypotheses EPH ODO NEO EPH ODO NEO “Basal Odonata” Hypothesis “Basal Ephemeroptera” Hypothesis EPH ODO NEO “Palaeoptera” Hypothesis

  26. Did DNA solve the problem? Ogden and Whiting (2003), Cladistics

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