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 Maracuto Creek 46 |
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| Stream code: | RGL_MrcutoCrk_46 |
| Basin: | Rio Grande de Loiza |
| State or Province: | Puerto Rico |
| Country: | USA |
| Latitude: | 18.359668 |
| Longitude: | -65.95452 |
| School: | Jose E. Aponte de la Torre |
The following are the most common invertebrates collected from this stream site.
Elmidae
- Order
- Coleoptera
- Family
- Elmidae
- Common name
- riffle beetle
We very commonly find adult and larval riffle beetles. The adults are clearly beetles, but the larvae can be confused with other orders. The forward pointing tooth on the front end of the larvae as described in the key can be a challenge to see, particularly in small individuals. Larvae are characterized by having a single tarsal claw at the end of their legs, which have 4 segments. Adults, on the other hand, have two tarsal claws at the end of each leg. Commonly encountered genera include
Dubiraphia,
Macroychu,
Optioservus,
Phanocerus,
Promoresia, and
Stenelmis.
Images of the adult and larval riffle beetles.
More information on Dubiraphia, Macronychus, Optioservus, Phanocerus, Promoresia, and Stenelmis.
Chironomidae
- Order
- Diptera
- Family
- Chironomidae
- Common name
- Nonbiting midge
- Tied fly
- Griffith's Gnat
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.
Philopotamidae
- Order
- Trichoptera
- Family
- Philopotamidae
- Common name
- fingernet caddisflies
Philopotomidae are net-spinning filtering collectors. A casual observer might sort them with Chironomidae, but a close look reveals six jointed legs. The faint white 'T' shaped labrum extending from the front of the head past the mandibles is diagnostic for the family (it is sometimes withdrawn and hard to see).
Image of the faint white 'T' shaped labrum. Common genera include Dolophilodes, Wormaldia, and Chimarra.
Hydropsychidae
- Order
- Trichoptera (caddisfly)
- Family
- Hydropsychidae
- Common name
- net spinning caddisfly
- Tied fly
- Emergent Sparkle Pupa, Vermont Hare's Ear
This family of net-spinning caddisflies is very abundant at several sites. They are important filtering collectors and are quite common at urban and agricultural sites where particles of organic material can be important food resources. Genus-level identification is possible for mature specimens and we will include the genera we found at your site if possible.
When using the key, some features that are challenging to see are the forked trochantin and the paired sclerites in the folds between segments. Other, more easily seen key features include filamentous gills on the abdominal segments and the sclerotization of the dorsal surfaces of all three thoracic segments. Keep in mind that with smaller or more immature specimens, genus-level ID may not be possible.
Commonly found genera include Cheumatopsyche, Ceratopsyche, and Hydropsyche. Less commonly, we have found Arctopsyche and Potamyia.
Images of the forked trochantin and the paired sclerites.
Ceratopogonidae
- Order
- Diptera
- Family
- Ceratopogonidae
- Common name
- biting midges
Members of this family look like very straight Chironomidae. They are very long and thin with a distinct head capsule and no prolegs. Some in the lab call them 'bamboo sticks' with eyes.
Image of the distinct head capsule.
Palaemonidae
- Order
- Decapoda
- Family
- Palaemonidae
This freshwater shrimp was found in streams in Puerto Rico. Its body is laterally compressed and the third pair of its pereiopods (walking legs) lack chelae. Unlike the primarily benthic crayfish we see in Vermont streams, palaemonid shrimp can be quite active in the water column and frequently jump out of the water when approached. Freshwater shrimp in two other families (Atyidae and Xiphocarididae) occur in Puerto Rico but we have not collected them at our stream sites.
Pseudothelphusidae
- Order
- Decapoda
- Family
- Pseudothelphusidae
- Genus
- Epilobocera
This is a freshwater crab found in the streams of Puerto Rico. We would usually provide anatomical descriptions here, but if you found a crab in a stream in Puerto Rico, it belongs to this family and in fact it is Epilobocera sinuatifrons. This species is endemic to Puerto Rico.
Maracuto Creek 46
