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Macroinvertebrates home

Streams project

 

Elmore Branch

These are the ten most common macroinvertebrates found in samples from Elmore Branch.

Click on images to zoom in. 

ORDER: Ephemeroptera
FAMILY: Baetidae 
GENUS: Baetis 

This mayfly has three "tails" and a unique head shape. Its gills are oval shaped and insert dorsally. The wing pad shape is an obvious characteristic. More mature nymphs have long, dark wing pads. SMC

ORDER: Diptera
FAMILY: Chironomidae

 Midge larvae tend to be the most common macroinvertebrate at our sites.  As with other Diptera, there are no true jointed legs.  Chironomids 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 the philopotamids.

ORDER: Trichoptera
FAMILY:
Philopotamidae
GENUS: Chimarra

Chimarra are distinguished from the other Philopotamidae by a prominent asymmetrical notch in the frontoclypeus as well as a prominent process on the femora which bears a single hair (seta). SMC

ORDER: Trichoptera
FAMILY:
Hydropsychidae
GENUS: Ceratopsyche

Ceratopsyche has a forked foretrochantin. The foretrochantin is the projection at the uppermost portion of the foreleg. The leg may need to be pulled away from the body to expose this feature.

Ceratopsyche have a large pair of sclerites underneath the prosternum. Note: the large single sclerite is the prosternal plate. SMC

 

 

ORDER: Ephemeroptera
FAM
ILY: Isonychiidae
GEN
US: Isonychia

This mayfly has unique long hairs on its forefemora as the main distinguishing characteristic (allowing anyone keying to move through quickly). Carefully observe the limbs because such hair can be matted down and therefore hidden in preserved wet specimens. The body of Isonychia is slim and "minnow-like" when observed dorsally. In specimens we collected, they were commonly brown and substantial, in length and width as compared to the very common Baetidae.

 

 

ORDER: Trichoptera
FAMILY: Hydropsychidae
GENUS and SPECIES:
Potamyia flava

Potamyia, like Cheumatopsyche, have a small or inconspicuous pair of sclerites under the prosternal plate that are difficult to see.  Contrast that with the larger pair of sclerites found on CeratopsycheTo access sclerites, it's best to gently pull the pronotum and mesonotum in opposite directions. Note: the large single sclerite is the prosternal plate. Posterior margins of sclerites on abdominal sternum 9 are entire (there are no notches).

The foretrochantin may or may not be forked, and there is a prominent anteriomedian projection on the anterial ventral apotome of the head.

ORDER: Coleoptera
FAMILY: Elmidae
GENUS: Stenelmis

Riffle beetles appear in the streams as adults and larvae. The larvae of Stenelmis have a sternum on the ventral side of the pronotum.

The adult Stenelmis has a clear separation between the thorax and abdomen as well as a more distinctly separate head as compared to other genera. SMC

ORDER: Trichoptera
FAMILY: Philopotamidae
GENUS: Dolophilodes

Dolophilodes stands out in the Philopotamidae family due to its slightly asymmetrical frontoclypeus on the anterior margin and its distinguishable projecting foretrochantin.


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ORDER: Diptera
FAMILY: Tipulidae
GENUS: Pedicia

Creeping welts or broad tubercules are found only on the venter of this tipulid. No spicules are present, but the surface may appear roughened under the microscope.

ORDER: Ephemeroptera
FAM
ILY: Heptageniidae
GEN
US:
Epeorus. 

A mayfly with two 'tails'!  This family of mayflies has distinctly flattened heads, and this particular genus has two tails and a unique gill arrangement.
NABS

The images are not a substitute for keying, but should serve as an aid in identifying common macroinvertebrates in samples.

Feedback - Partner schools: send us specimens not included above.  Taxonomists: click to email: Declan McCabe

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