Stonefly (Plecoptera) Glossary
Updated 5 Dec 2006
abdomen - Segments at the back end of a stonefly containing the gut and reproductive organs. Does not have legs or wings (wingpads) attached. The cerci, filaments, or tails are attached to the end of the abdomen.
allochthonous - Sources of carbon or nutrients from outside the stream. In the rocky mountains, most allochthonous materials are riparian plant leaves and pine needles that fall in the stream. Shredders such as Zapada spp. grow faster in the fall as there is more for them to eat. Also see http://en.wikipedia.org/wiki/Allochthonous
antennae - The first pair of appendages on the stoneflies head. Used for sensing the environment.
apterous - Without wings.
apomorphy - Similar characteristics that identify two or more animals as related. Used rather strictly when working on cladistics. Same as synapomorphy.
aquatic - species that lives in water for part or all of its life.
Beringia - A prehistoric geographic province consisting of the unglaciated land north of the North American ice sheets during the various glaciation events. This area stretches between the Lena River in eastern Siberia in the west to the Richardson and McKenzie mountains on the eastern boundary of the Yukon Territory in Northern Canada. Biogeographers are interested in the animals and plants that survived glaciation in this area.
bifid - Forked into two or y-shaped. Sometimes forked at the very end.
biogeography - The study of species distributions over time. Events such as continental drift, orogenesis, glaciation and lowered sea levels forming land bridges among other things can affect species distributions. In the nearctic, the land bridge across the Bering strait during the last ice age affected many stonefly distributions.
brachypterous - Short winged (see apterous)
carinate - a body surface that is ridged or keeled.
carnivore - An animal (predator) that eats other animals (prey). They usually have piercing or cutting mouthparts. Scavenging, stealing prey from other predators and cannibalism are other ways some carnivores obtain food. Predator - prey relationships have been a popular arena of ecological research.
cercus or cerci - Tails or appendages at the end of the abdomen. Also called caudal filaments.
cervical - ventral or front side of neck.
cladistics - A branch of science that studies the evolutionary relationships between species. Scientists compare similiar traits between species. Sometimes it is clear when a trait changes in a closely related animal. This slightly changed trait is called a derived trait or similarity. Then scientists try to figure out when species branched off from each other and create the bush or tree-like diagrams (cladograms) you see with taxa names at the ends of the branches. This field is growing with the use of computers and genetic sequences. http://en.wikipedia.org/wiki/Cladistics
CPOM - Coarse Particulate Organic Matter. Leaves that fall in the stream. See FPOM
detritivore - An animal that eats decomposing organic matter. In streams and ponds, leaves that have fallen in the water are a major part of the diet.
diapause - A time when growth is suspended. Stonefly eggs may diapause after being laid and hatch months later to avoid difficult environmental conditions. Some stoneflies can diapause as nymphs. Of the species that have been studied so far, they diapause during their 4th, 5th or 6th instars.
diagnosis - insect description with excruciating detail and many perplexing fine illustrations. Sometimes needed to assist with bugs that are hard to identify. Diagnoses are usually published in peer reviewed scientific journals.
dorsal - The back or up side of a stonefly nymph. See ventral.
drumming - Stoneflies drum or tap their abdomens against the substrate to communicate with members of the opposite sex. See hammer and duet.
duet - As part of their mating rituals, adult stoneflies sometimes drum together, in a sort of call and response pattern.
endemic - Found in a restricted geographical area. Not widespread, has a small range.
epiproct - the central adult male genitalia. Used to identify stoneflies to species. Of course rarely the absence of an epiproct also helps identify some species (i. e. Diura)
exuvia - Molt skin or shuck. Since invertebrates (including stoneflies) don't have a skeleton, they support their body with a rigid exoskeleton made of chitin. As a result they need to shed their old skin in order to develop and grow larger. This shed skin is called an exuvia and may be caught in nets in the water or seen on rocks or vegetation near streams when the nymphs are emerging to their usually winged adult form. Flyfishermen may use shucks to help decide which artificial flies to fish with. See instar.
FPOM - Fine Particulate Organic Matter.
furcal pits - pits or depressions on the ventral side of the thorax. Used to identify Perlodidae nymphs. To see this, look through a microscope and flip the nymph on its back and study their chest between the middle legs. Hard to see on tiny or poorly preserved nymphs.
gill - used to absorb oxygen from the water. If a stonefly has gills they are always fingerlike, never flat plates like mayflies. Plecoptera may variously have gills attached to the neck or cervical region, the thorax and or only the first few or very last segments of the abdomen in one of our more primitive families the Perlidae.
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glossae - Mouthpart, the two middle lobes of the labium. Sometimes hard to see in tiny or poorly preserved specimens. To view this feature, flip the nymph on its back and try to hold the head up or back so you can look at the underside or ventral side of the head. The nymphs, even though dead may resist this, be firm but gentle.
See paraglossae, labial palp.
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Glossae = the pair in the center
Paraglossae = middle pair of appendages, considered equal to the glossae in this drawing.
Labial palps = outside multi-segmented appendage |
hammer - Many male stoneflies have a hammer on the underside of their abdomen. They use it to drum on branches or the ground to attract a mate.
instar - the nymph between molts. Time spent in each instar depends on the length of the life cycle. Stoneflies seem to have an indeterminate number (10-22+) of instars between hatching from their egg to emerging as an adult. They may moult fewer or more times depending upon environmental conditions. Many stonefly species have not had instar analysis done in the field or lab yet.
Introduction to the Stoneflies of Gunnison County, Colorado
keel - carina or elevated ridge.
labial palp - segmented mouthparts on the outside of the labium. Has chemoreceptors used to feel and taste. See paraglossae
lacinia - mouthpart, the inner bladelike part of the maxillae. Often has teeth, brushes, spines or knobs used for identification.
lotic - about flowing water, streams or rivers, habitat for stoneflies.
macropterous - long winged. Most stonefly adults are long winged.
monophyletic - from greek: of one stem. All the creatures under discussion share a common ancestor and all descendants of the ancestor are included.
multivoltine - Life cycle short enough to have several generations per year. Leads to the observation of several adult flight periods per year in light traps.
naiad or nymph- immature aquatic nymph or larvae. Lives mostly in streams or rivers.
Nearctic - The Nearctic includes most of North America, Greenland and the mountains of Mexico. (Southern Florida is in the Neotropic ecozone.)
nomenclature - the system of naming things. Changes in stonefly nomenclature over the years make old papers and keys hard to read until you are familiar with the name changes. In spite of the occasional frustration we suffer dealing with this, the name changes usually make sense when you look carefully at the bug under consideration. I translated the old names to new ones for some of the papers in the bibliography for this website. Stewart and Stark's excellent book "Nymphs of North American Stonefly Genera" has a review of name changes too. Here are some useful links:
Curiosities of Biological Nomenclature by Mark Isaac - fun and a good introduction to scientific names.
http://home.earthlink.net/~misaak/taxonomy.html
Integrated Taxonomic Information System -Check if names have changed
http://www.itis.gov/
orogenesis - Mountain building.
| paraglossae - mouthpart used taxonomically to split the carnivorous stonefly families from the detritivorous families. Specifically, its the lateral terminal lobe of the labium. See glossae and labial palp. |
Glossae = the pair in the center
Paraglossae = middle pair of appendages,
considered longer than the glossae in this drawing,
Labial palps = outside multi-segmented appendage |
plesiomorphy - An ancestral trait common to an entire clade or group of related stoneflies. Used when discussing cladistics.
prognathous - Having a protruding lower jaw. For example in stoneflies, the lower mouthparts including mandibles and lacinia may even protrude beyond the upper part of the face in some species. Hypognathous is a synonym.
rheocrene - A spring that emerges from the ground to become a stream immediately. There is enough water to flow and maintain at least a small stream.
riparian - Wetland zone or area bordering a stream or river. Some characteristic plants in the Gunnison basin include willow (Salix), sedges (Carex) and Aspen (Populus) or Spruce/Fir (Picea/Abies) forest. Habitat for adult stoneflies.
semivoltine - The entire life cycle from egg to nymph to adult and back to egg takes two years.
sensu stricto or stricto sensu - Taxonomists use these latin phrases to indicate "in the stricter sense", abbreviated s.s. Stricto sensu is often used when discussing a subgenera with the same name as the genus under consideration. This may apply to other taxonmic levels such as families or species.
shredder(s) - organisms who eat leaves and poop fine particle organic matter (FPOM). They are an important part of detritus processing and nutrient cycles in freshwater habitats. Shredders often have a life cycle adapted to the large influx of leaves into the water during leaf drop in the fall. My favorite family of stonefly shredders in the Gunnison Basin is the Nemouridae.
synapomorphy - A morphological feature that related insects have and unrelated insects do not have. Used to infer common ancestry. A shared, derived taxonomic or genetic character. Same as apomorphy.
systellognatha - Refers to the carnivorous stoneflies that have the mouthparts of the labium with the paraglossae longer than the glossae. Chloroperlidae, Isoperlidae, Perlidae, Perlodidae. Used by Frison in his revisions of 1935 and 1942.
systematics - a branch of science that assigns scientific names to organisms. There were large changes in plecoptera systematics during the 19th and 20th centuries. Some of the publications that relate directly to Gunnison Basin plecoptera such as Knight and Gaufin (1966) have old names and may be difficult to interpret until the reader translates the nomenclature changes. Chapter 16: Guide to Changes in Generic Names in Stewart and Stark (2002) is a helpful overview. Bill Stark's Nearctic Stonefly List http://www.nearctica.com/nomina/oddbugs/plecop.htm has synonyms too.
thorax - The three segments behind the head. Labeled from the first segment behind the head and to the back: prothorax, mesothorax, metathorax. Each segment has a pair of legs in both nymphs and adults. Most adults have wings attached to the mesothorax and metathorax.
univoltine - One year life cycle. See multivoltine and semivoltine
USGS - United States Geological Survey. They provide many kinds of data and maps. For example, they host the valuable Stoneflies of the United States website http://www.npwrc.usgs.gov/resource/distr/insects/sfly/sflyusa.htm edited by Boris Kondratieff and Ken Baumann.
ventral - The bottom, underside or stomach side of a Plecoptera nymph. See dorsal
voltinism - Number of years it takes the stonefly to complete its life cycle from egg through nymph, adult and back to the egg. See multivoltine, semivoltine and univoltine
Website Index
wingpad - Wing developing in its container attached to the meso and meta-thorax of older stonefly nymphs. Mature nymphs have large conspicuous wingpads. Right before the stonefly emerges the wingpads may turn black or begin to puff up to be ready for emergence.
References
Peckarsky,BL; Fraissinet,PR; Penton,MA; Conklin Jr.,DJ 1990: Freshwater Macroinvertebrates of Northeastern North America. Cornell University, Ithaca, NY. 442 pages.
Has a glossary at the end with useful definitions for the wide variety of taxa discussed in the book.
Stewart,KW; Stark,BP 2002: Nymphs of North American Stonefly Genera. 2nd edition The Caddis Press, Columbus, Ohio. 510 pages.
Introductory chapters were used heavily to develop this glossary.
Brown, Wendy S. 2004 Plecoptera or Stoneflies of Gunnison County, Colorado
www.gunnisoninsects.org
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