Baetidae

from Wikipedia, the free encyclopedia
Baetidae
Cloeon dipterum, female

Cloeon dipterum , female

Systematics
Trunk : Arthropod (arthropoda)
Class : Insects (Insecta)
Subclass : Flying insects (Pterygota)
Order : Mayflies (Ephemeroptera)
Family : Baetidae
Scientific name
Baetidae
Leach , 1815

The Baetidae are the most species-rich family of mayflies. Their aquatic larvae show a body shape adapted to swimming. With the exception of New Zealand and the Antarctic, Baetidae are distributed almost worldwide.

features

Baetidae are small to medium-sized mayflies, with fore wing lengths between 2 and 12 millimeters. The adults resemble other mayflies in their body shape. The shape of the eyes in males is typical of the family: the complex eyes are divided into two separate eyes, one pair of which points to the side and one pair, known as " turban eyes ", upwards. The position of a suture (suture) in the head capsule is more difficult to recognize, but of systematic importance: the epicranial suture runs in front of the lateral ocelli . The adults have crystal clear (hyaline) unspotted and unspotted wings, the hind wings are always much smaller than the forewings, in a number of genera they are completely regressed, so that only one pair of wings is preserved. In the veins of the forewings, short veins that are not connected to the other veins towards the wing joint, the intercalary veins, fall towards the rear wing edge. Depending on the species, there are always one (as with many mayflies) or two intercalary veins per space. The legs are rod-shaped, as is usual with mayflies, the front legs of the males are greatly elongated. The tarsi of the middle and hind legs are also four-limbed, not five-limbed as in most mayflies. The first tarsal link is immovably fused with the tibia. In the male, the tarsi of the forelegs have two unequal claws, one pointed and sickle-shaped, the other blunt. The abdomen, which is elongated in the shape of a cylinder, has at the end, like most mayflies, two multi-limbed, elongated tail threads. Typically for the family, the paired copulation organs (penes) of the males are not sclerotized .

The larvae of the Baetidae are rounded, teardrop-shaped ("torpedo-shaped"), so they can swim quite well. They have three tail threads, of which the middle one is of the same length or noticeably shorter than the lateral ones, depending on the species. In the European species, the lateral tail threads have a border made of fine bristles, these only sit on the inside; in some genera they are absent (in Europe: Acentrella ). On the side of the abdomen there are seven pairs of oval-shaped, usually slightly pointed, movable gill leaves that are traversed by trachea . In some genera, the gill leaflets (except for the last pair) are doubled. The hypognathic (vertical, with the mouthparts down) of the larvae has long antennae that are always longer than the head. The following features are characteristic of the structure of the mouthparts : the labrum has a constriction in the middle, the left mandible has a movable, long, movable prostheca, toothed at the tip.

ecology

The larvae of the Baetidae live in all types of water, with the main distribution in streams ( Rhithral ). Fewer species also specialize in stagnant water. They mostly live on the bottom of the water. In Central Europe, the genera Baetis and Acentrella live almost exclusively on the bottom of the water, where they crawl around on the substrate ("clamp type"), the other genera are also quite good buoyant ("swimming type"), where they row with the tail threads covered with a dense bristle border . Floating forms only occur in slowly flowing or standing water. Most European species graze the organic coating ( biofilm ) or growth ( periphyton ) consisting of algae and bacteria on stones or other hard substrates, or they feed on soft, partially decomposed organic matter ( detritus ), especially dead plant remains. In other regions, their way of life is more diverse. In South America, for example, predatory ( Harpagobaetis ) and filtering ( Chane ) genera are known, the species of the genera Mayobaetis and Spiritops specialize in waterfalls.

The adults, like all mayflies, do not ingest food and are short-lived. Copulation takes place in flight, a few species reproduce (thelytok) parthenogenetically , that is, only females hatch, unfertilized eggs. The females usually lay the eggs under water, on the underside of stones or the like, they crawl into the water from the bank or from protruding stones. Some species, such as Cloeon dipterum , show ovoviviparity. They dab their eggs in flight into the water, the young larvae hatch immediately, usually before the egg has reached the bottom.

distribution

The Baetidae are distributed almost worldwide. Their distribution over the fauna kingdoms is relatively even, they make up about 20 to 25 percent of the total number of mayflies in almost all regions, in the Orientalis and the Afrotropic their share is even higher at 36 and 47 percent. 156 species are given for the Palearctic and 82 for Europe.

Phylogeny and Systematics

The position of the Baetidae within the mayflies is currently not confirmed and is still being discussed controversially between different researchers. Their classification in a suborder "Schistonota" is hardly represented today, the "Schistonota" are mostly considered paraphyletic . The formerly used superfamily Baetoidea is also no longer justified. In more recent investigations, both on the basis of morphology and on a molecular basis, based on the comparison of homologous DNA sequences, a very basic position emerges. In an earlier molecular study, they were even considered the most primitive group at times, with all other recent mayflies as sister groups . However, according to later findings, this position belongs to the monotypical Chinese family Siphluriscidae, with the only species Siphluriscus chinensis . Their position on the small family Isonychiidae is still unclear. Accordingly, the mayflies (with the exception of Siphluriscus ) are either sister groups of the Baetidae, or a common clade of these and the Isonychiidae. The family Siphlaenigmatidae (with the only species Siphlaenigma janae from New Zealand), which is very similar according to morphological criteria, especially the larvae, is no longer necessarily considered to be closely related today; the unifying characteristics could rather be due to convergence .

The family is often divided into the subfamilies Baetinae and Cloeoninae, but their monophyly has not been proven. Structuring the family on the basis of morphological characteristics is difficult because many characteristics show a high degree of homoplasia .

With around 833 species in 97 genera, the Baetidae are the most species-rich family of the Ephemeroptera.

The following genera occur in Europe:

swell

  • Ernst Bauernfeind, Tomas Soldan: The Mayflies of Europe (Ephemeroptera). Brill Scientific Publishers, 2012. ISBN 978-90-04-26088-7 .
  • Nikita Kluge: The Phylogenetic System of Ephemeroptera. Springer, 2013. ISBN 978-94-007-0872-3 .

Individual evidence

  1. ^ Carolina Nieto (2010): Cladistic analysis of the family Baetidae (Insecta: Ephemeroptera) in South America. Systematic Entomology 35: 512-525. doi: 10.1111 / j.1365-3113.2010.00523.x
  2. ↑ a b c d Helen M. Barber-James, Jean-Luc Gattolliat, Michel Sartori, Michael D. Hubbard (2008): Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater. Hydrobiologia 595: 339-350. doi: 10.1007 / s10750-007-9028-y
  3. ↑ Family Baetidae. Fauna Europaea version 2.6.2 (August 2013)
  4. ↑ Buffagni, A., Armanini, DG, Cazzola, M., Alba-Tercedor, J., López-Rodríguez, MJ, Murphy, J., Sandin, L. & Schmidt-Kloiber, A .: Dataset "Ephemeroptera". freshwaterecology.info - the taxa and autecology database for freshwater organisms, version 6.0, accessed on June 15, 2016
  5. ^ WP McCafferty & GF Edmunds (1976): The higher classification of the Ephemeroptera and its evolutionary basis. Annals of the Entomological Society of America 72 (1): 5-12.
  6. ^ T. Heath Ogden & Michael F. Whiting (2005): Phylogeny of Ephemeroptera (mayflies) based on molecular evidence. Molecular Phylogenetics and Evolution 37: 625-643. doi: 10.1016 / j.ympev.2005.08.008
  7. ↑ Chang-Fa Zhou & Janice G. Peters (2003): The nymph of Siphluriscus chinensis and additional imaginal description: a living mayfly with Jurassic origins (Siphluriscidae new family: Ephemeroptera). Florida Entomologist 86 (3): 345-352. doi : 10.1653 / 0015-4040 (2003) 086 [0345: TNOSCA] 2.0.CO; 2
  8. Jump up ↑ TH Ogden, JL Gattoliat, M. Sartori, AH Staniczek, T. Soldan, MF Whiting (2009): Towards a new paradigm in mayfly phylogeny (Ephemeroptera): combined analysis of morphological and molecular data. Systematic Entomology 34: 616-634. doi: 10.1111 / j.1365-3113.2009.00488.x
  9. ↑ Michael T. Monaghan & Michel Sartori (2009): Genetic contributions to the study of taxonomy, ecology, and evolution of mayflies (Ephemeroptera): review and future perspectives. Aquatic Insects Vol. 31, Supplement 1: 19-39. doi: 10.1080 / 01650420902734145

Web links

Commons : Baetidae  - collection of images, videos and audio files