Pseudostigmatidae

Taxobox
name = Pseudostigmatidae


image_caption =
regnum = Animalia
phylum = Arthropoda
subphylum = Hexapoda
classis = Insecta
ordo = Odonata
subordo = Zygoptera
familia = Pseudostigmatidae
familia_authority = Tillyard, 1917
subdivision_ranks = Genera
subdivision =
*"Anomisma"
*"Coryphagrion"
*"Mecistogaster"
*"Megaloprepus"
*"Microstigma"
*"Pseudostigma"

Pseudostigmatidae is a family of tropical damselflies, known as helicopter damselflies, giant damselflies or Forest Giants. The family includes the largest of all damselfly species. They specialize in preying on web-building spiders, and breed in phytotelmata, the small bodies of water held by plants such as bromeliads.

Range

The species traditionally placed in Pseudostigmatidae are all Neotropical. Two range as far as northeastern Mexico: "Mecistogaster ornata" occurs in Tamaulipas and "Pseudostigma aberrans" in both Tamaulipas and Nuevo León. [Westfall and May, 589-596.]

In 2006, molecular phylogenetic analysis revealed that the African damselfly "Coryphagrion grandis" belonged within family Pseudostigmatidae, close to genus "Mecistogaster". This finding suggests that the family dates back to before the breakup of the supercontinent Gondwana. [Groenevelda; Fincke, "Use of Forest", 104.]

Naiad

As with other damselflies, the young—known as naiads, nymphs, or larvae—have gills and live in fresh water. The tropical forests where pseudostigmatids live typically have few ponds and lakes, so the water that collects in or on plants is an important habitat. Water-filled tree holes and bromeliad tanks are the most dependable and widespread habitats available to pseudostigmatid naiads, and a majority of species use tree holes. Tree hole species are rarely found in bromeliads and vice versa, probably because bromeliad phytotelmata have much higher oxygen content than those in tree holes. One species apparently specializes in bamboo stems that have filled with water after being breached by other insects. In areas where tree holes are uncommon, naiads of a few species can be found in fallen fruit husks, though these phytotelmata may dry out quickly or be overturned by animals. Fallen palm bracts provide an even more unstable habitat, and no pseudostigmatid naiads have ever been found in them. There remain six species known as adults whose larvae have not yet been identified.Fincke, "Use of Forest", 105-108.]

The naiads are top predators in their aquatic habitats, feeding on the larvae of mosquitoes and other flies, tadpoles, and the naiads of their own and other odonate species.

Adult

Adults are exceptionally large for damselflies, with wingspans as high as 19 cm (7.5 in.) reported for "Megaloprepus" [Groeneveld.] and body length up to 13 cm (5.1 in.) for "Pseudostigma aberrans". [Hedström and Sahlén.] The pterostigma—a thickened, pigmented cell found on the leading edge of the wing in other odonates—is either missing or else modified into a pseudostigma of several cells. In some species the pseudostigma is a large colored spot covering most of the tip of the wing. [Westfall and May, 587-588.] Mary and William Beebe described the appearance of "Mecistogaster" flying in the rainforest of Guyana:

Spinning through the aisles made by the giant columns of tree-trunks, were curious translucent pin-wheels .... the wing spots revolved rapidly while the rest of the wings became a mere gray haze. [Quoted in Corbet, 356.]

Adult lifespans as long as 7 months have been recorded (in "Megaloprepus"). [Fincke, "Population Regulation", 119.]

Foraging

As far as is known, all pseudostigmatids feed on web-building spiders, which they pluck out of their webs. The only recorded exception to this uniform diet is that they occasionally take wrapped prey from a web rather than the spider who wrapped it. Most Odonata are generalist predators; the Pseudostigmatidae may be the only true specialist predators in the order.Corbet, 355-357.] Spiders provide a large amount of nutrition per unit of prey, and since empty webs are often taken over by other spiders, a pseudostigmatid that learns web locations may be able to take prey from them again and again. [Corbet, 346.]

They forage in sun flecks and the gaps created by fallen trees, where there is enough light to see spider webs. [Fincke, "Use of Forest", 108.] Several species have been observed searching for webs by flying up one side of a tree and down the other side. When they locate one they hover in front of it. To catch a spider they first fly backward, then quickly fly forward to grab it in their forelegs. Then they back away again and perch to consume the spider, removing the legs before eating the body. Though this careful forward-and-back approach minimizes contact with the web, they often preen after eating to remove any strands that do adhere to them.

Pseudostigmatids prey on spiders about 3-6mm in body length, avoiding larger ones. They prefer soft-bodied spiders, which can be eaten more quickly. They have never been observed feeding on ground-dwelling spiders, though they do catch web-building spiders that drop to the ground or retreat to a rolled leaf in an attempt to escape. The complex barrier webs that most "Nephila" spiders build protect them from predation by pseudostigmatids.

Reproduction

Some species mate opportunistically while foraging in light gaps. In others, males briefly hold mating territories in sunny gaps, or defend a large phytotelma and mate with females who lay eggs there. [Fincke, "Use of Forest", 109.]

All pseudostigmatids have ovipositors capable of cutting into plant tissue to insert eggs, which is the most common mode of oviposition in damselflies. Yet one species, "Mecistogaster martinezi", has been observed apparently "tossing" eggs from its abdomen onto the surface of the water while in flight. This behavior may allow the insect to avoid predators such as spiders from which it would otherwise be unable to escape in the small, confined space of a phytotelma. [Corbet, 21, 33, 592-593.] However, Ola Fincke has suggested that the "M. martinezi" female may simply have been using its long abdomen to test for water in the tree hole before alighting to lay eggs—a behavior observed in a related species—and that the eggs seen floating on the water afterward were laid by mosquitoes. [Fincke, "Use of Forest", 107.]

pecies list

* "Anomisma abnorme" McLachlan, 1877
* "Coryphagrion grandis" Morton, 1924
* "Mecistogaster amalia" (Burmeister, 1839)
* "Mecistogaster amazonica" Sjöstedt, 1918
* "Mecistogaster asticta" Selys, 1860
* "Mecistogaster buckleyi" McLachlan, 1881
* "Mecistogaster jocaste" Hagen, 1869
* "Mecistogaster linearis" (Fabricius, 1776)
* "Mecistogaster lucretia" (Drury, 1773)
* "Mecistogaster martinezi" Machado, 1985
* "Mecistogaster modesta" Selys, 1860
* "Mecistogaster ornata" Rambur, 1842
* "Mecistogaster pronoti" Sjöstedt, 1918
* "Megaloprepus caerulatus" (Drury, 1782)
* "Microstigma anomalum" Rambur, 1842
* "Microstigma maculatum" Hagen in Selys, 1860
* "Microstigma rotundatum" Selys, 1860
* "Pseudostigma aberrans" Selys, 1860
* "Pseudostigma accedens" Selys, 1860Schorr et al.]

Notes

References

* cite book
last = Corbet
first = Phillip S.
authorlink =
coauthors =
title = Dragonflies: Behavior and Ecology of Odonata
publisher = Cornell University Press
date = 1999
location = Ithaca, NY
id = ISBN 0-8014-2592-1
pages = 281-282

* cite journal
last = Fincke
first = Ola M.
authorlink =
coauthors =
title = Population Regulation of a Tropical Damselfly in the Larval Stage by Food Limitation, Cannibalism, Intraguild Predation and Habitat Drying
journal = Oecologia
volume = 100
issue = 1/2
pages = 118–127
publisher =
date = 1994
url = http://faculty-staff.ou.edu/F/Ola.M.Fincke-1/Fincke94ecologia.pdf
doi =
id = ISSN 0029-8549
accessdate = 2007-07-14

* cite conference
last = Fincke
first = Ola M.
authorlink =
coauthors =
title = Use of Forest and Tree Species, and Dispersal by Giant Damselflies (Pseudostigmatidae): Their Prospects in Fragmented Forests
booktitle = Fourth WDA International Symposium of Odonatology, Pontevedra (Spain), July 2005
editor = Adolfo Cordero Rivera
pages = 103-125
publisher = Pensoft Publishers
date = 2006
location = Sofia—Moscow
url = http://faculty-staff.ou.edu/F/Ola.M.Fincke-1/06%20-%20Fincke.pdf
doi =
id =
accessdate = 2007-06-22

* cite journal
last = Groenevelda
first = Linn F.
coauthors = Viola Clausnitzerb and Heike Hadrysa
title = Convergent Evolution of Gigantism in Damselflies of Africa and South America? Evidence from Nuclear and Mitochondrial Sequence Data
journal = Molecular Phylogenetics and Evolution
volume = 42
issue = 2
pages = 339–46
date = 2007
url = http://linkinghub.elsevier.com/retrieve/pii/S1055790306002296
doi = 10.1016/j.ympev.2006.05.040
accessdate = 2007-07-19

* cite journal
last = Hedström
first = Ingemar
authorlink =
coauthors = Göran Sahlén
title = A key to the adult Costa Rican "helicopter" damselflies (Odonata: Pseudostigmatidae) with notes on their phenology and life zone preferences
journal =
volume = 49
issue = 3-4
pages = 1037–1056
publisher = Rev. Biol. Trop
date = 2001
url = http://www.scielo.sa.cr/scielo.php?pid=S0034-77442001000300024&script=sci_arttext
doi =
id = ISSN 0034-7744
accessdate = 2007-06-23

* cite web
last = Schorr
first = Martin
coauthors = Martin Lindeboom and Dennis Paulson
title = World Odonata List
work = Slater Museum of Natural History
date = January 2007
url = http://www.ups.edu/x6140.xml
accessdate = 2007-07-19

* cite book
author = Westfall, Minter J. and May, Michael L.
title = Damselflies of North America
publisher = Scientific Publishers
location = Jodhpur
year = 1996
pages =
isbn = 0-945417-93-4
doi =