Lepidostomatidae

Ulmer, 1903

Bizarre Caddisflies

Genus Guides

1

is a of caddisflies (Trichoptera) established by Georg Ulmer in 1903. Larvae construct distinctive cases, often square or rectangular in cross-section, using materials such as leaf pieces, sand grains, or rarely living snails. The family has a predominantly Northern Hemisphere distribution with some ranging south to Panama and New Guinea. Larvae are aquatic and primarily associated with streams and rivers.

Lepidostoma cascadense 01 by Libby Avis, Centre for Biodiversity Genomics. Used under a CC0 license.Lepidostoma cascadense 02 by Libby Avis, Centre for Biodiversity Genomics. Used under a CC0 license.Lepidostoma cinereum 02 by Libby Avis, Centre for Biodiversity Genomics. Used under a CC0 license.

Pronunciation

How to pronounce Lepidostomatidae: //lɛpɪˌdɒstəˈmætɪdiː//

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Identification

Larvae recognized by their characteristic case architecture: typically square or four-sided rectangular cross-sections constructed from leaf pieces, sand grains, or mineral particles. Some use cylindrical sand-grain cases in early instars, transitioning to four-sided leaf cases in final instars. distinguished by -level genitalic and wing venation characters; specific identification requires examination of male genitalia, which shows geographical variation in some species (more protrusive and complex in southwestern Japan of Goerodes naraensis).

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Habitat

Aquatic larvae inhabit streams, rivers, and lake beds, typically in riffle-pool sections or debris accumulations. Some occupy specific microhabitats: within sediments and debris (Lepidostoma cascadense) or on debris surfaces (Lepidostoma unicolor). Larvae of Lepidostoma abruptum found in small debris pools with leaf litter and small branches in evergreen forests.

Distribution

Widely dispersed globally with concentration in Northern Hemisphere. Documented from: North America (Oregon, Vermont), Europe (Denmark, Norway, Sweden), Asia (Japan, Thailand, Ukraine), and southward to Panama and New Guinea.

Seasonality

Variable by and latitude. Lepidostoma quercina shows maximum larval growth corresponding to autumn leaf fall; L. cascadense pupates May-June after slow winter growth; L. unicolor grows rapidly June-July. Goerodes naraensis in Sapporo with larvae appearing midsummer, as fifth instar, emerging late spring. Some tropical species (Lepidostoma abruptum) non-seasonal.

Diet

Larvae feed on allochthonous plant detritus, primarily conditioned deciduous leaves (alder leaves preferred by Lepidostoma quercina) and conifer needles (processed by L. cascadense and L. unicolor). Consumption rates increase with temperature, food quantity, and conditioning time of leaves.

Life Cycle

Development includes , larva (typically 5 instars), pupa, and . Larval capsule widths measurable to determine instars. Some with as final instar larvae; others show multivoltine patterns (Goerodes nukabiraensis: three in two years). occurs in constructed cases.

Behavior

Larvae exhibit seasonal longitudinal distribution shifts in some ; Goerodes japonicus group shows sequential downstream summer distribution with overlapping zones. Case construction changes with instar in some species: cylindrical sand-grain cases early, four-sided leaf cases in final instar. Rare behavioral record: Crunoecia irrorata has been observed incorporating living snails (Terrestribythinella) into larval cases.

Ecological Role

of coarse particulate organic matter in stream . Processing of leaves and conifer needles contributes to fine particulate organic matter availability for collector organisms. Fecal production by Lepidostoma quercina estimated sufficient to support substantial portion of simuliid production in Oregon streams. Generally minor component of secondary production relative to other but significant in organic matter processing .

Sources and further reading