היומן של paul_dennehy

I've been working on identifying a set of four oft-confused Feltia species, and I'm making this post to describe the differences between them.

The species in question are Feltia herilis, Feltia jaculifera, Feltia subgothica, and Feltia tricosa. Two of them are easily identifiable from decent photos of fresh specimens, and two of them require either a close-up of the male antennae or a clear view of the hindwings to identify. Here's how I recognize them.

Feltia jaculifera has two of the veins edged in pale scales all the way out into the terminal area of the wings, like this:

Feltia herilis has the costa of the wings dark, contrasting strongly with the pale streak through the wings, like this:

Its orbicular spot also tends to be a U-shape, like this:

As opposed to more of a V-shape in the other three species, like this:

This is a somewhat variable feature in all the species though, and should not be used as a definitive ID feature.

By contrast, Feltia subgothica and Feltia tricosa both have the costa paler in color, so it matches the color of the pale streak through the middle of the wing, a feature shared with F. jaculifera, like this:

While also lacking the pale-edged veins in the terminal area, a feature shared with F. herilis, like this:

So recognizing F. herilis, F. jaculifera, and F. subgothica/tricosa is relatively straightforward. Separating F. subgothica from F. tricosa is a bit trickier. Males of these two species have very different antenna setae: F. subgothica has stubby setae that stick straight out from the antennae, like this:

F. tricosa males, on the other hand, have longer setae that bend over at a 90 degree angle, like this:

This is often visible in macro photos, but the antennae need to be in-focus to see it. Females of this pair have very tiny setae on the antennae, and this feature cannot be used to separate them. For example:

If the hindwings are visible, the hindwing color can also be used to separate these two, though with lower confidence than the antenna features. Here is a photo by Kyhl Austin of a series of these species, with F. tricosa on the left and F. subgothica on the right, showing the hindwing colors:

Note how dark F. tricosa is compared to F. subgothica. But also note that this trait is somewhat variable.

A final note is that some other Noctuines, especially Euxoa, are often misidentified as Feltia by iNat's Computer Vision. If the orbicular spot is closed at the top, forming a full circle, like this, that's a good sign that the moth is not one of the four species described in this post:

This information should be sufficient to prevent most misidentifications that occur in this group on iNaturalist. Luckily there is a taxon available called "Subgothic and Tricose Darts (Complex Feltia subgothica)" to place F. subgothica/tricosa observations which lack sufficient antenna detail to be identified to species. So all observations of these species in decent condition should be placeable below the genus level!