Updates from July 2, 2021

A few days after unexpectedly collecting a female dun of this species, but in a sad, bedraggled shape, I went back to the same pool to see if I could find more. I was able to catch this one male dun during a dusk emergence dominated by other species, and he made it home in prime shape for photos.

This dun is smaller than would normally be expected for Drunella flavilinea, but it seems to fit the physical description of that species fairly well. I wasn't sure from the dun pictures alone, so I was hoping it would molt into a spinner. It never made it out of the dun's shuck, but it did begin the process, which allowed me with great care to tease out the last couple abdominal segments of the spinner from the still tightly attached dun shuck, enabling a more confident ID based on the shape of the spinner's penes and sub-genital plate. I also collected a nymph of flavilinea in the same river on the same evening, as well as a shed exuvium that looked large enough to belong to an emerging dun. The other possibility I considered for a while based on the dun was Drunella pelosa, which would be the right size, but the other characteristics don't fit.

This female spinner was collected with a male from the same swarm.

This specimen keys pretty well to Cultus. Key characteristics observed under the microscope but not necessarily apparent on my photo are the lack of submental gills (or any gills at all), the lack of short, stout setae on the occiput or anterolateral prothoracic margins, and the lack of a low knob below the subapical tooth on the lacinia. Species known to be found in Washington are Cultus pilatus and Cultus tostonus. It clearly does not fit the description by Frison (1942) of Diploperla pilata, as Cultus pilatus was first named. I cannot find a detailed description of the nymph of tostonus, but Ricker 1952 describes a defining character of the adults, "Head mostly yellow, the only important dark marking being the bands which join the anterior to the lateral ocelli ; median pronotal stripe, at its middle, about one-fifth of the width of the pronotum." The nymph shows a very dark pattern fitting that description on the head (likely retained into adulthood) and the pronotal stripe is about the right width, too. Given that visual description, the range, and the poor fit to pilatus, I'm calling this Cultus tostonus.

A few of these nymphs turned up in my kick net sample, with this being the only one fully mature and ready to emerge. It keys pretty straightforwardly to Ameletus suffusus, particularly because of the triangular dark patch on the labrum. The abdominal markings are close but don't quite match other drawings, likely just individual variation.

I collected this female dun with a male dun and a female spinner of the same species.

I collected this female spinner with a male dun and a female dun of the same species.

A couple days earlier I caught a male spinner of this species with some wing damage and missing tails, so I went back to the same pool try to get one more intact. This one has some leg damage, but between the two specimens you can get an idea what the whole insect looked like. There were small clouds of Cinygma dimicki spinners again over the same two small, specific locations in the pool, which is an interesting testament to how repeatably they choose their ideal mating habitat. I was able to capture this one and a female.

Key characteristics verified under the microscope: -The head has 3 ocelli. -Maxillary palp has 5 segments, with the second segment rounded. In some of the pictures it looks like 6 with the 3rd segment rounded, but the basal "segment" in that case isn't part of the palp. -Foretibiae lack preapical spurs. -Pronotum with mesal setose warts widely spaced. All of this very clearly indicates Glossosomatidae. Beyond there: -The tibial spur counts (fore / middle / hind tibiae) are 2, 4, and 4. -From the pictures, the hind wing discoidal cell is closed, not open. Subfamily Glossosomatinae. -The upper and lower parts of the mesepisternum are separated by a constriction, not a transverse suture. Microscope picture included. This leads to a very confident genus ID of Glossosoma. I don't have the information to take it to species.

I collected this male dun with a female dun and a female spinner of the same species. Identification was initially difficult because I didn't catch a male spinner, and this dun was missing its legs. I was able to tease the spinner's penes out of the dun's shuck after it expired, although the shape was pretty similar. Fortunately, the shape is a distinctive match to the Epeorus albertae species group. In the key in Needham et al (1935), it keys to Epeorus youngi, which is now considered a synonym of albertae. It's also a very plausible dun version of this spinner collected a few years earlier, a few drainages to the north, at a similar time of year. Additionally, the female dun and spinner collected with this one match very closely those I've collected in the past.