The monitoring protocol for the stream-dwelling salamanders of Ohio relies heavily upon the "morpho-species" concept. Basically, this identification system requires the surveyor to identify different species of salamander larvae in the field, which are then assigned a generic identification ("species A," "species B," etc.). Then, the number of each morpho-species captured is counted, and a representative of each morpho-species is preserved as a voucher specimen and returned to the survey coordinator. This voucher specimen will be used to determine the actual species captured before being cataloged into a museum collection.
To identify different species of salamander larvae captured, carefully compare the larvae to one another, looking specifically for differences in the following characteristics:
Overall body shape,
Width of the rear legs,
Morphology of the feet and toes
Width of head in relation to the body,
Slope of head,
Presence/absence of dark stripe through eye,
Location of dorsal fin attachment to body,
Presence/absence of pigment on throat region,
Presence/absence of pigment on ventral body surface,
Presence/absence of pigment, stripes, or spots on body,
With the morpho-species concept, you are trying to identify differences between individuals that indicate they are of different species. However, larvae of the same species change considerably from hatching to metamorphosis, and like all species, individual and geographic variation is common. It is conceivable that one breeding site could contain the larvae of up to 10 species, but most sites will have no more than 3 different salamander species utilizing the stream for breeding.
If you are unsure if two different larvae are of the same species or not, TREAT THEM AS DIFFERENT SPECIES! Assign each different morpho-species identifications, preserve one of each group, and count the number of larvae assignable to each group. If the larvae are later identified as the same species, the survey coordinator can easily combine the numbers from the two groups.