Hex Mayflies
Hexagenia limbata
The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.
The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.
Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
Stonefly Species Salmoperla sylvanica (Bighead Springflies)
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.
Description from GBIFthe Global Biodiversity Information Facility
Source: Description Of The Male Terminalia Of Two Western Nearctic Perlodinae (Pictetiella Expansa (Banks) And Salmoperla Sylvanica Baumann & Lauck)
Description: Male. For a habitus description refer to Baumann and Lauck (1987). Head and pronotum shown in (Fig. 12). Ninth tergum with pair of lateral humps (LH), apices covered in sensilla basiconica, lateral margins covered in long fine hairs (Fig. 13). Tenth tergum deeply cleft, membranous with a large basal anchor (BA) which extends to base of the epiproct cowl (Fig. 14). Epiproct cowl (EC) membranous with sparse setae (Fig. 13) and flanked by two rectangular paragenital plates (PP) at base (Fig. 14). Hemitergal lobes (HL) rounded produced inward, sclerotized and flattened at apices bearing sensilla basiconica anteriorly and fine hairs posteriorly (Fig. 14). Epiproct short, boxlike in dorsal aspect, basal portion slightly narrowed, covered in backward directed scale-like setae, setae absent on apex (Figs. 15, 16). Lateral stylets short, broad and darkly sclerotized terminating in outward directed hooks, present laterally at epiproct base (Fig. 16). Aedeagus with pair of large posterolateral lobes at base (Fig. 17). Basal portion of aedeagus covered with uniformly spaced spinulae (Fig. 17). Apex of aedeagus bulbous, glabrous (Fig. 17).
Start a Discussion of Salmoperla sylvanica
Stonefly Species Salmoperla sylvanica (Bighead Springflies)
Species Range
Common Name
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by Baumann, R.W. & Lauck, D.R. (1987) Salmoperla, a new stonefly genus from northern California (Plecoptera: Perlodidae). Proceedings of the Entomological Society of Washington 89, 825–830.