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Montana Field Guide

Montana Field Guides

Tiny Forestfly - Malenka tina

Native Species

Global Rank: G3
State Rank: SNR

Agency Status


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General Description
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Diagnostic Characteristics
Adult male morphology: Body length is 5 mm; total length to tip of wings is 6.5 mm. Color is brown. Two pairs of branched gills occur on the neck ventrally. Wings have no pigmented markings. Abdominal segments are mostly membranous through the eighth segment, but dorsally they have more sclerotized anterior margins and a sclerotized plate occurs on either side of the median line ventrally. The ninth sternite has an elongate lobe from the anterior margin; the posterior margin is triangularly produced with a terminal knob slightly upturned. The subanal lobes are triangular and sclerotized near the outer margin, terminating in two strong hooks, one shorter and stouter than the other. The tenth tergite is sclerotized dorsally with a posterior sclerotized plate bearing the supra-anal process on its tip; the process is erect, bent forward at the tip and mostly sclerotized. The cerci are membranous, with rounded sclerotized knobs pointing inward at the base (Ricker 1952).

Adult female morphology: Body length is 7.5 mm; total length to wing tips is 9 mm. The female is similar to the male in general morphological details but is slightly larger in size. The 8th sternite is completely bisected by a notch which is margined by heavy sclerotization in its narrow anterior third (Jewett 1954).

Range Comments
Rangewide, Malenka tina reportedly occurs in Washington, Oregon, Montana, Idaho, Utah, and Nevada (NatureServe 2006). In Idaho, the species has been collected in Blaine, Butte, Idaho, Lemhi, Minidoka, and Twin Falls counties (Baumann et al. 1977; Newell and Minshall 1978). In Montana, we have no specific site collection records, although a specimen has been reported to be from Missoula County (Baumann et al. 1977).

The larvae are found in small mountain streams (Newell and Minshall 1978). Baumann (personal communication 2005) reported that this species was collected in 1964 in seeps outside the main Big Wood River channel. Most of the Nemouridae species are shredders or collector-gatherers utilizing coarse plant materials (Merritt and Cummins 1996).

Food Habits
Merritt and Cummins (1996) report that members of this family are trophically shredder-detritivores; eating large particulate organic materials such as detritus, leaves and plants.

Reproductive Characteristics
No information is available.

Malenka tina has no federal or state agency status at the present time. Based on available information, the species appears to have a broad "Coast, Cascade, and Rocky Mts." geographic distribution. It also has a broad north-south and east-west county distribution within Idaho. Baumann et al. (1977) report that Malenka tina is known from six Idaho counties but also observe that M. tina is "rather restricted in its distribution." In Idaho, the distribution of M. tina and its ecological needs require further study.

Threats or Limiting Factors
Specific threats to Idaho or MT populations of Malenka tina have not been identified. In general, stonefly populations are affected by changes to aquatic habitat such as alteration of flow patterns, streambed substrate, thermal characteristics, and water quality. Alteration and degradation of aquatic habitat is the primary concern for Idaho populations.

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Citation for data on this website:
Tiny Forestfly — Malenka tina.  Montana Field Guide.  .  Retrieved on , from