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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Ventral view of a Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Larva from the Yakima River in Washington
With a bit of help from the microscope, this specimen keys clearly and unsurprisingly to Hydropsyche.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Mayfly Species Pseudiron centralis

Where & when

In 5 records from GBIF, adults of this species have been collected during June (60%) and July (40%).

In 6 records from GBIF, this species has been collected at elevations ranging from 618 to 4511 ft, with an average (median) of 3953 ft.

Species Range

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Female Spinner

Body length: 13 mm
Wing length: 13 mm

A yellowish species; abdomen dorsally with a broad brown band; longitudinal veins pale, cross veins black, humeral cross vein pale. Only the female imago is known.

Head yellow. Basal antennal joints, the median portion of the vertex, and most of the space between and laterad of the lateral ocelli, light reddish. Pronotum ruddy brown, the lateral margins yellowish. Mesonotum light brown tinged with yellow; sternum yellow tinged with brown. Femora light amber, each with a median and an apical purplish red band; tibiae and tarsi pale yellowish. Wings hyaline, rather narrow. Longitudinal veins pale, the subcosta and radius amber-tinged. Humeral cross vein and those of the anal area pale; all others of the fore wing black, thickened in the basal costal and subcostal areas. Those of the stigmatic area are faint and evenly anastomosed. Abdominal tergites light yellow, the posterior margins brown; broad brown median patches, narrowed posteriorly, form a continuous dorsal band, its outer edge irregular, much like that of Pentagenia vittigera. The three apical tergites are almost wholly brown, and the postero-lateral margins of tergites 1-7 are deeper in color than other portions of the margin, thus presenting the appearance of a lateral row of brown spots. Sternites pale yellowish. The subanal plate is rather short, narrowed posteriorly to about half the width of the ninth sternite; the apical margin has a sharp V-shaped excavation. Tails pale whitish, joinings not darker.

Male Spinner

Described in Needham et al (1935) as Pseudiron meridionalis
Body length: 13.5 mm
Wing length: 10.5 mm

A reddish brown species; all veins reddish brown, the humeral cross vein very dark.

Head yellowish, shaded with brown anterior to the ocelli, which are black-ringed at the bases. Below and laterad of each lateral ocellus is a small red mark. A purplish black streak below each antenna, near the corner of the eye; another on the median carina. Eyes deep bluish black. Pronotum yellowish red. Mesonotum reddish brown; scutellum and a median area near the anterior margin slightly paler. Posterior margins on each side of scutellum purplish black. Pleura yellowish, sutures reddish brown. Sternum pale reddish brown, the anterior median portion of the mesosternum yellowish. Femora reddish, each with three distinct dark reddish brown bands, located at base, apex and middle. Fore tibia pale reddish; darker red at the base, its apex blackish; tarsus yellow, the joinings and the entire distal joint dusky. Tibiae and tarsi of middle and hind legs yellow; tibiae reddish at extreme base; tarsal joinings and claws brownish. The first fore tarsal joint is about three-fourths the length of the second; third slightly shorter than the second; the fore femur is only slightly longer than the tibia.

Wings hyaline, venation reddish to purplish brown, the main veins of the costal margin (especially the subcosta) yellowish basally. A distinct reddish stain occupies the costal and subcostal spaces immediately before the bulla. Basal cross veins of the costal and subcostal spaces, including the humeral cross vein, are rather heavily margined; in the costal area, heaviest toward the subcosta. All cross veins somewhat heavier than the longitudinals. Those of the stigmatic area anastomose in the apical portion of that space, forming two rows of cells, of which those nearer the costa are smaller.

Abdomen reddish brown; tergites darker than the sternites, especially the three apical ones, which are also brighter. Tergites 1-4 narrowly pale on the posterior margins; 5 and 6 with distinct dark posterior margins, which are less evident on 7-9. All tergites are rather widely paler along the lateral margin, and have an indistinct wide paler median band. On each side of the median line, within this pale band, a slender darker triangle arises from the posterior margin, its apex almost attaining the anterior margin on the basal tergites, but extending only to the middle on the apical ones. On the anterior margin of each, at the mid-dorsal line, is a short black streak. Sternites faintly pinkish; unmarked, except for faint indications of a pale brown submedian triangle on each side, as on the tergites, and a narrow streak on each side. These are most clearly defined on the apical sternites. Tails pale whitish, faintly tinged with reddish at the extreme base; joinings not darker. Genitalia amber yellow. Penes rather similar to Metretopus norvegicus, but more widely separated apically; apical margin not lobed. Third joint of the forceps slightly longer than the fourth; the two terminal joints together are almost two-thirds as long as the second joint. Genitalia as in fig. 115.

Start a Discussion of Pseudiron centralis


  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Pseudiron centralis

Species Range
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