Brewster River
From WikiEducator
The following are the most common invertebrates collected from this stream site.
Contents
Chironomidae
Midge larvae tend to be the most common macroinvertebrate at our sites. As with other Diptera, there are no true jointed legs. Chironomidae do have a pair of prolegs at each end and preserved individuals tend to curl into a 'C'. Identification past family requires slide-mounted heads. We have seen philopotamid caddisflies misidentified with the chironomids and we suspect that that happens when samples are being sorted from trays. Under a microscope, six prominent legs can be seen on members of the caddisfly family Philopotamidae.
More information on Philopotamidae.
Baetis
- Order
- Ephemeroptera
- Family
- Baetidae
- Genus
- Baetis
- Common name
- The Little Olive
- Tied fly
- Sawyer Pheasant Tail Nymph
This mayfly has three "tails" and a unique head shape. Its gills are oval shaped and insert dorsally. More mature nymphs have long, dark wing pads.
Image of the long, dark wing pads.
Helicopsyche
- Order
- Trichoptera
- Family
- Helicopsychidae
- Genus
- Helicopsyche
- Common name
- snailcase caddisfly
- Tied fly
- speckled peter
This caddisfly genus has one local species. It looks rather like a snail but has lots of sand grains covering it's 'shell' which is really a case. The anal claws have closely-spaced teeth, much like a small comb.
Image of the closely-spaced teeth
Baetidae
This mayfly has either two or three cerci ("tails") and a unique head shape. Its gills are oval shaped and insert dorsally. Commonly encountered genera include Acerpenna, Baetis and Pseudocloeon.
More information on the genera:
Drunella
The mayfly Drunella is distinguished by its large femoral “biceps;” these femora have tubercles on the leading margins. Gills are present on segments 3-7.
Psephenus
The true "water penny" is commonly found in the waters sampled. Psephenus has a rounded shape with relatively smooth edge. The false water penny, whose edges are serrated, has a more oval appearance. The gills on the ventral surface are found only in the true water pennies.
Another genus encountered in this family is Ectopria.
Antocha
This small dipteran in the cranefly family is quite common. It is distinguished from most other dipterans we found by the 'creeping welts' that appear as prominent dark stripes along the abdomen. The dark head is usually partly exposed; however, it can be pulled back into the thoracic cavity during preservation.
Perlodidae
Stoneflies in the Perlodidae family do not have branching gills from leg bases. When observing their mouthparts, the glossae and paraglossae form a large three-pronged notch, or opening. The hind wing pads are divergent. Cerci, or "tails," are as long or longer than the abdomen.
Images of mouthparts, thehind wing pads and the ventral view.
Capniidae
Capnia stoneflies have hind wing pads that are are broad as they are long. An important distinction of the Capniidae family is the membranous pleural folds that run down the posterior abdomen segments 1-9. These look like two lines running parallel down the back of the abdomen. Capnia are distinguished by femurs and tibia of forelegs with less than 20 fine hairs and no dorsal femoral fringe hairs.
Epeorus
- Order
- Ephemeroptera
- Family
- Heptageniidae
- Genus
- Epeorus
- Common name
- The Quill Gordon
- Tied fly
- Quill Gordon
This is the only Heptageniidae genus present in this area with two tails!