Plecoptera are an
orderIn scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s, commonly known as
stoneflies. There are some 1,700 recorded
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
worldwide, and new ones are still being discovered. Stoneflies are believed to be one of the most primitive groups of
NeopteraNeoptera is a classification group that includes almost all the winged insects, specifically those that can flex their wings over their abdomens...
, with close relatives identified from the
CarboniferousThe Carboniferous is a geologic period and system that extends from the end of the Devonian period, about 359.2 ± 2.5 Ma , to the beginning of the Permian period, about 299.0 ± 0.8 Ma ....
and Lower
PermianThe Permian
[The term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named...]
geological periods, while true stoneflies are known from fossils only a bit younger. The modern diversity however apparently is of
MesozoicThe Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the "Mesozoic" was "Secondary" The Mesozoic Era is one of three geologic eras of the...
origin.
Plecoptera are found in both the
SouthernThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
and
Northern hemisphereThe Northern Hemisphere is the half of a planet that is north of the equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator...
s, and the populations are quite distinct although the
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
ary evidence suggests that species may have crossed the equator on a number of occasions before once again becoming geographically isolated.
All species of Plecoptera are intolerant of
water pollutionWater pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater. All water pollution affects organisms and plants that live in these water bodies and in almost all cases the effect is damaging either to individual species and populations but also to the natural...
and their presence in a stream or still water is usually an indicator of good or excellent water quality.
Stoneflies have a generalised anatomy, with few specialised features.
Plecoptera are an
orderIn scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s, commonly known as
stoneflies. There are some 1,700 recorded
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
worldwide, and new ones are still being discovered. Stoneflies are believed to be one of the most primitive groups of
NeopteraNeoptera is a classification group that includes almost all the winged insects, specifically those that can flex their wings over their abdomens...
, with close relatives identified from the
CarboniferousThe Carboniferous is a geologic period and system that extends from the end of the Devonian period, about 359.2 ± 2.5 Ma , to the beginning of the Permian period, about 299.0 ± 0.8 Ma ....
and Lower
PermianThe Permian
[The term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named...]
geological periods, while true stoneflies are known from fossils only a bit younger. The modern diversity however apparently is of
MesozoicThe Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the "Mesozoic" was "Secondary" The Mesozoic Era is one of three geologic eras of the...
origin.
Plecoptera are found in both the
SouthernThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
and
Northern hemisphereThe Northern Hemisphere is the half of a planet that is north of the equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator...
s, and the populations are quite distinct although the
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
ary evidence suggests that species may have crossed the equator on a number of occasions before once again becoming geographically isolated.
All species of Plecoptera are intolerant of
water pollutionWater pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater. All water pollution affects organisms and plants that live in these water bodies and in almost all cases the effect is damaging either to individual species and populations but also to the natural...
and their presence in a stream or still water is usually an indicator of good or excellent water quality.
Description and ecology
Stoneflies have a generalised anatomy, with few specialised features. They have simple
mouthpartsInsects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
with chewing
mandiblesIn arthropods, the mandible is either of a pair of arthropod mouthparts used for biting, cutting and holding food. Mandibles are often simply referred to as jaws. The arthropods with mandibles form the clade Mandibulata, comprising the extant subphyla Myriapoda, Crustacea and Hexapoda...
, long, multi-segmented
antennaeAntennae in biology have historically been paired appendages used for sensing in arthropods and crustaceans. More recently, the term has also been applied to cilium structures present in many cell types of eukaryotes....
, large compound eyes and two or three ocelli. The legs are robust, with each ending in two claws. The
abdomenIn vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
is relatively soft, and may include remnants of the nymphal gills even in the adult. Both
nymphIn biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes in gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
s and adults have long paired cerci projecting from the tip of their abdomens.
The name "Plecoptera" literally means "
braidA braid is a complex structure or pattern formed by intertwining three or more strands of flexible material such as textile fibers, wire, or human hair...
ed-wings", from the
Ancient GreekAncient Greek is the historical stage in the development of the Greek language spanning across the Archaic , Classical , and Hellenistic periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek...
plekein (πλέκειν, "to braid") and
pteryx (πτέρυξ, "wing"). This refers to the complex venation of their two pairs of wings, which are
membranousA biological membrane or biomembrane is an enclosing or separating amphipathic layer that acts as a barrier within or around a cell. It is almost invariably a lipid bilayer, composed of a double layer of lipid molecules and proteins that may constitute close to 50% of membrane...
and fold flat over the back. Stoneflies are generally not strong fliers, and some species are entirely wingless.
A few wingless species such as the Lake Tahoe Benthic Stonefly (
"Capnia" lacustra) or
Baikaloperla are the only known insects that are exclusively aquatic from birth to death. Some true water bugs (Nepomorpha) may also be fully aquatic for their entire life, but can leave the water to travel.
The females lay hundreds or even thousands of eggs in a ball which they initially carry about on their abdomen, and later deposit into the water. The eggs typically take two to three weeks to hatch, but some species undergo
diapauseDiapause is a physiological state of dormancy with very specific triggering and releasing conditions. It is used as a means to survive predictable, unfavourable environmental conditions, such as temperature extremes, drought or reduced food availability...
, with the eggs remaining dormant throughout a dry season, and hatching only when conditions are suitable.
The nymphs are aquatic and live in the
benthic zoneThe benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
of well-oxygenated lakes and streams. A few species found in New Zealand and nearby islands have terrestrial nymphs, but even these inhabit only very moist environments. The nymphs physically resemble wingless adults, but often have external gills, which may be present on almost any part of the body. In addition, they can also respire through the general body surface, and some even lack gills altogether. Most species are herbivorous as nymphs, feeding on submerged leaves and benthic algae, but many are hunters of other aquatic arthropods.
The insects remain in the nymphal form for one to four years, depending on species, and undergo anything from 12 to 33
moltsEcdysis is the moulting of the cuticula in arthropods and related groups . Since the cuticula of these animals is also the skeletal support of the body and is inelastic, it is shed during growth and a new, larger covering is formed...
before emerging and becoming terrestrial as adults. The adults generally only survive for a few weeks, and emerge only during specific times of the year. Some do not feed at all, but those that do are herbivorous.
Systematics
Traditionally, the stoneflies were divided into two suborders, the
"Antarctoperlaria" (or
"Archiperlaria") and the
ArctoperlariaArctoperlaria is a suborder of stoneflies.-Distribution:See -References:* Zwick. 1969. Das Phylogenetische System der Plecopteren als Ergebnis vergleichend-anatomischer Untersuchgen. 291 pp., Kurzfassung: 4 pp....
. However, the former simply consists of the two basalmost superfamilies of stoneflies, which do not seem to be each other's closest relatives. Thus, the "Antarctoperlaria" are not considered a natural group (despite some claims to the contrary).
The Arctoperlaria, meanwhile, have been divided into two infraorders, the Euholognatha (or Filipalpia) and the Systellognatha (also called Setipalpia or Subulipalpia). This corresponds to the phylogeny, with one exception: the Scopuridae must be considered a basal family in the Arctoperlaria, not assignable to any of the infraorders. Alternatively, the Scopuridae were placed in an unranked
cladeA clade is a term used in modern alpha taxonomy, the scientific classification of living and fossil organisms, to describe a monophyletic group, defined as a group consisting of a single common ancestor and all its descendants.[The term "monophyletic group" is used in this article...]
"Holognatha" together with the Euholognatha (meaning approximately "advanced Holognatha"). But the Scopuridae do not appear significantly closer to the Euholognatha than to the Systellognatha.
In addition, not adopting the clades Antarctoperlaria and Holognatha allows for a systematic layout of the Plecoptera that adequately reproduces phylogeny, while retaining the traditional
ranked taxaIn biological classification, rank is the level in a taxonomic hierarchy. The most basic rank is that of species, the next most important is genus, and then family...
.
Basal lineages ("Antarctoperlaria")
- Superfamily Eusthenioidea
- Family Diamphipnoidae
- Family Eustheniidae
- Superfamily Leptoperloidea
- Family Austroperlidae
- Family Gripopterygidae
Suborder ArctoperlariaArctoperlaria is a suborder of stoneflies.-Distribution:See -References:* Zwick. 1969. Das Phylogenetische System der Plecopteren als Ergebnis vergleichend-anatomischer Untersuchgen. 291 pp., Kurzfassung: 4 pp....
- Basal family Scopuridae
- Infraorder Euholognatha
- Family Capniidae
Capniidae, the small winter stoneflies, is a family of insects in the stonefly order . It constitutes one of the largest stonefly families, containing some 300 species distributed throughout the Holarctic...
(ca. 300 species) - small winter stoneflies
- Family Leuctridae - rolled-winged stoneflies
- Family Nemouridae
Nemouridae is a family of stoneflies. This is one of the largest stonefly families with around 400 described species with a mainly Holarctic distribution. Members of this family are commonly known as spring stoneflies or brown stoneflies...
(ca. 400 species) - spring stoneflies
- Family Notonemouridae
- Family Taeniopterygidae
Taeniopterygidae are a family of stone flies with about 80 described extant species. They are commonly called willowflies or winter stoneflies and have a holarctic distribution.Adults are usually smaller than 15 mm.-Species:Sources are , and...
(ca. 75 species) - winter stoneflies
- Infraorder Systellognatha
- Family Chloroperlidae (100+ species) - green stoneflies
- Family Perlidae
Perlidae is a family of stoneflies.There are 15 genera with a total of 72 species . The majority of the Perlidae are found in the East. The life cycle length can be between 1 and 3 years. They adults emerge in the summertime. The adults are very active and known to be attracted to light sources...
(ca. 400 species) - common stoneflies
- Family Perlodidae
-Perlodid Stoneflies:Perlodidae; also known as the Perlodid stoneflies, stripetails, or springflies; are a family of stoneflies.-Natural History:...
(250+ species)
- Family Peltoperlidae
Peltoperlidae Claassen 1931, also known as roachlike stoneflies or roachflies, are a family of stoneflies.The family Peltoperlidae comprises 6 genera and 18 known species. Species are semivoltine, meaning that their life cycle is composed of 1 to 2 years. Adults of the family usually emerge in late...
(ca. 50 species) - roachlike stoneflies
- Family Styloperlidae (ca. 7 species)
- Family Pteronarcyidae
Pteronarcyidae, also known as giant stoneflies or salmonflies, is a family of the order Plecoptera.- Natural history :There are two genera of Pteronarcyidae; Pteronarcys is found in all of North America, while Pteronarcella is found only in the west. The two genera comprise 10 distinct species, two...
(ca. 12 species) - salmonflies, giant stoneflies