Caddisflies: a caddisfly
Dolophilodes columbia

(Trichoptera: Philopotamidae:Philopotaminae)
Profile prepared by Sarah Foltz Jordan and Julia Janicki, The Xerces Society for Invertebrate Conservation.

Dolophilodes columbia is a filter-feeder with the larvae occuring in running waters with moderate current. The Tucannon River, 35 miles south of Pomeroy in the Umatilla National Forest in Columbia county, Washington is the only known locality of this species and there has only been two specimens collected.  Accordingly many aspects of this species is unknown, including its life history, the adult flight period, its abundance, detailed habitat information etc..  Re-evaluation of this species’ status at the known site and surrounding area is critical in identifying both its current distribution and its conservation needs.

conservation status
Global Status (2005): G1G3
Rounded Global Status: G2- Imperiled
National Status (United States): N1N3
State Status: Washington: SNR
(NatureServe 2009).
identification

Adult: A small, frail, moth-like insect belonging to the Philopotamidae family. In North America, adults in this family are black and up to 1 cm (0.39 in.) in length (Wiggins 2004). They are distinguished from related families by the presence of ocelli and the mesoscutum lacking setose warts (Wiggins 2004). The wing venation in this family is complete and generalized (Wiggins 2004). The species differs from the closely related and widespread D. aequalis and D. pallidipes in the elongated apical segment of the clasper, the narrowed distal portion of the basal segment of the clasper, and the small semi-circular tergum 10 from dorsal view (Denning 1989). For detailed descriptive information, Denning (1989) provides a complete description for adults, including figures.

Immature: Larvae in this family are caseless, constructing groups of silken nets shaped like fingers. The nets range in size up to 60 mm in length and 5 mm in diameter, with a small opening at the posterior end of each net to ensure flow of water through the net (Wiggins 2004). Larvae in this family range in length up to about 16 mm (0.62 in.) and are distinguished by the orange-brown head and pronotum which contrasts with the creamy white color of the rest of the body (Wiggins 2004). The membranous (as opposed to sclerotized) labrum is also diagnostic of the family (Wiggins 1996). Only the head and pronotum are sclerotized (not the meso- and metanota) and a prominent black band extends across the posterior margin of the pronotum (Wiggins 2004). The antennae, located at the anterior margin of the head capsule, are minute (Wiggins 1996, 2004). The abdomen is whitish, lacking gills and lateral fringes (Wiggins 1996).  See Wiggins (1996) to distinguish the genus Dolophilodes from other genera in the family.

life history
The life history of this species is unknown, but most trichopterans in temperate latitudes are univoltine (Wiggins 1996), developing from the egg through five larval instars, pupating and emerging as adults within a single year. The flight period of this species is unknown; the only known specimens (two adults) were collected on June 6th (Denning 1989). Adults of the closely related Doliphilodes pallidipes can be found from late May to September (Schmid 1982), D. aequalis can be found in late May (Nimmo 2001), and adults of another North American species, D. distinctus, can be found throughout the year, with wingless females during the winter months (Wiggins 2004). Larvae of this species have not been collected. Members of this family feed on fine particulate organic matter which they filter from currents using elongate, sack-like nets of silken mesh (Wiggins 1996).
distribution

This species is described from a single locality in Columbia county, Washington: the Tucannon River, 35 miles south of Pomeroy in the Umatilla National Forest (Denning 1989). Abundance estimates for this species have not been done.

Forest Service/BLM Lands: This species is documented on the Umatilla National Forest in Washington.

habitat associations
Larvae in this family occur in running waters with moderate current (Wiggins 2004). The elongate, silken, sack-like nets are fastened to the undersides of rocks or other substrates and distended into the current (Wiggins 2004). Among the filter-feeding Trichoptera, this family utilizes the finest detrital particles (Wiggins 1996) along with diatoms and algae (Williams and Williams 1981). Detailed habitat information for this species is unknown, although the closely related D. aequalis is known from small, usually turbulent mountain streams, and D. pallidipes from small streams (Nimmo 2001a, 2001b).
threats
Since this species is not well-known, the following assessment of threats is general. Most trichopteran species have highly specific preferences with regard to water temperature, velocity, dissolved-oxygen levels, and substrate characteristics, and are therefore sensitive to a wide array of habitat alterations. The loss of trees through timber harvest poses serious threats, since trees provide shade that maintains appropriate water levels and temperatures for larval and pupal development. Continued global climate change may also threaten this species; projected changes due to this phenomenon include increased frequency and severity of seasonal droughts and flooding, reduced snowpack to feed river flow, increased siltation, and increased air and water temperatures (Field et al. 2007), all of which could unfavorably impact this species’ habitat and long-term survival. Sedimentation, eutrophication, and chemical pollution caused by development and road construction could also impact this species.
conservation needs
Inventory: Re-evaluation of this species’ status at the known site and surrounding area is critical in identifying both its current distribution and its conservation needs. Abundance estimates for this species at new and known sites would also assist future conservation efforts, since population size is important in evaluating the stability of a species at a given locality. Small streams with moderate currents are good candidates for new population sites.

Management: Protect all new and known sites and their associated watersheds from practices that would adversely affect any aspect of this species’ life cycle. Riparian habitat protection, including maintenance of water quality, substrate conditions, and canopy cover, would likely benefit and help maintain this species.

Research: Although several illustrations are provided in Denning (1989), a better figure of the 10th tergite and one of the aedeagus are to be desired (Wisseman 2009, pers. comm.). Wisseman (2009, pers. comm.) recommends that both the holotype (deposited in the James Entomological Collection, Washington State University, Pullman, Washington) and the paratype (deposited at California Academy of Sciences) be re-examined to see if they are indeed a unique species, or if they are in the range of variation for D. aequalis or D. pallidipes.

references

Denning, D.G. 1989. Eight new species of Trichoptera. Pan-Pacific Entomologist 65(2): 123-131.Wiggins, G.B. 1996. Larvae of the North American Caddisfly Genera. 2nd ed. University of Toronto Press, Toronto. 424pp.

Field, C.B., Mortsch, L.D., Brklacich, M., Forbes, D.L., Kovacs, P., Patz, J.A., Running, S.W. and M.J. Scott. 2007. Chapter 14: North America. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Parry, M.L., Canziani, O.F., Palutikof, J.P., van der Linden, P.J. and Hanson, C.E., eds.). Cambridge University Press, Cambridge, UK. Available at: www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter14.pdf.

NatureServe. 2009. “Dolophilodes columbia.” NatureServe Explorer: An online encyclopedia of life [web application]. Feb. 2009. Version 7.1. NatureServe, Arlington, Virginia. 15 Sep. 2009.

Nimmo, A.P. 2001b. Species Page – Dolophilodes pallidipes. Entomology Collection, University of Alberta. Available at: http://www.entomology.ualberta.ca/searching_species_details.php?b=caddisflies&r=312&ref=b&o=15&c=6&s=2357# (Last accessed 16 Sep 2009)

Schmid, F. 1982. Revision des trichopteres Canadiens. II. Les Glossosmatidae et Philoptamidae (Annulpalpia). Memoires de la societe entomologique du Canada. 122: 76

Wiggins, G.B. 1996. Larvae of the North American Caddisfly Genera. 2nd ed. University of Toronto Press, Toronto. 424pp.

Wiggins, G.B. 2004. Caddisflies: the underwater architects. University of Toronto Press, Toronto. 292pp

Williams D.D. and Williams N.E. 1981. Some aspects of the life history and feeding ecology of Dolophilodes distinctus (Walker) in two Ontario streams. Proceedings of the Third International Symposium on Trichoptera. Perugia (Italy), 1980. G. P. Moretti (ed.), pp. 421-429. The Hague: W. Junk.

Wisseman, R.W. 2009. Personal communication with Sarah Foltz Jordan

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