Synonyms and other taxonomic changes
Numbers
There are 8 species in North America north of Mexico and over 100 species worldwide.
Identification
A key to species can be found in Carico (1973).
Arrangement of eyes, apparently typical of family:
The transverse suture of the
lorum is distinct and v-notched in this genus. This feature sets it apart from the other two genera of this family.
Overview of identification tips for Dolomedes species:
D. albineus - Variable in appearance. Can be extra hairy (look for pale, stiff hairs that give a bristly appearance), look for the white band along the 'face', may also have a white carapace. Not all of the aforementioned features may be present on any given individual. Often found on trees or walls. A mossy-green color palette also indicates this species. The eye region is also slightly elevated compared to other species in the genus.
D. gertschi - looks similar to D. scriptus, but only found in the Gila River watershed in Arizona and New Mexico.
D. okefinokensis - the adult females are the largest of the genus. Difficult to separate from D. tenebrosus where their ranges overlap (Gulf Coast area) without genital examination. Based on BugGuide photos of this species, it may be possible to identify in the field by looking for the light areas on the sides of the clypeus to have a more mottled appearance than those of D. tenebrosus.
D. scriptus - look for White 'W' marks on abdomen (with a more pronounced and "sculptured" appearance than those of D. tenebrosus or D. vittatus) and a stripe running down the entire carapace. Often difficult to separate from D. tenebrosus.
D. striatus - looks somewhat similar to
Pisaurina brevipes and plainer variants of
D. triton. Look for the middle brown band to become darker on the edges where it meets the light-colored stripes.
D. striatus also has a more northeasterly range. Carapace stripes are generally straighter and positioned further from the edges than those of
D. triton.
D. tenebrosus - this species is frequently found away from water. Look for an incomplete stripe running down the middle of the carapace and a light area surrounded by dark on the clypeus (between the eyes and the jaws), though do note that sometimes D. scriptus and D. vittatus can have a smaller version of that marking. "W" markings on the abdomen are usually less distinct than those of D. scriptus, but more distinct than those of D. vittatus
D. triton - Pretty distinct spots on abdomen (however, these spots may not always be apparent) and carapace stripes are more curved towards the edge of the carapace than those of D. striatus or P. brevipes.
D. vittatus - Look for the large & very dark mark in the center of the carapace - it will be larger and darker than the analogous markings on D. scriptus. Abdominal patterning is usually less distinct than D. scriptus or D. tenebrosus.
Range
Widespread primarily in the east.
Also restricted locally in the west (D. triton, D. scriptus, and D. gertschi).
Exact distribution within these countries will be added when time permits.
Ranges from Carico, 1973
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albineus - Southeastern US
scriptus - Across most of the eastern US & southeastern Canada. (Based on a review of observations on iNaturalist,
D. scriptus is nearly nonexistent in the Gulf Coast region.)
striatus - Northeastern US & southeastern Canada.
tenebrosus - Across most of the eastern US & southeastern Canada.
triton - Widespread in the east, but also in the west & all of Canada & southern Alaska.
vittatus - Across most of the eastern US & southeastern Canada.
Habitat
Aquatic and moderately moist forest habitats.
Food
Mostly aquatic insects. They have also been known to occasionally catch small fish, hence the common name "Fishing Spider".
Print References
Carico, J. E., 1973. The Nearctic species of the genus Dolomedes (Araneae: Pisauridae). Bulletin Museum of Comparative Zoology Harvard 144: 435-488. (
Full Text Here)
Ubick
et al., 2004. Spiders of North America: an identification manual
(2)
