Pale Maple Stilt Caloptilia honoratella

A new British species, first seen in Surrey in 2017 and then in Kent and Suffolk in 2019. It arrived in Norfolk the following year. Formerly given the vernacular name Pale Maple Slender.

This species is extremely similar to other species in the genus, particularly Scarce Maple Stilt Caloptilia hemidactylella. Some individuals suspected by some of being honoratella have proved in fact to be hemidactylella, and unless external characters are clarified in due course, identification should be confirmed by checking the genitalia.

This female was caught by Laura King and was Norfolk's second record. Note the signa in the ductus bursae shown in the inset.

female Pale Maple Stilt Caloptilia honoratella showing genitalia, Lower Hellesdon (Norfolk, UK), 9th May 2021

This male was caught by Murray Smith and was Norfolk's fourth record. So far as I am aware the male genitalia don't have any particularly characteristic features but lack some found in other species. The most obvious difference from hemidactylella (and some other similar species such as falconipennella) seems to be the lack of cornuti in the aedeagus, however some care needs to be taken here. The cornuti in hemidactylella are found in the vessica outside of the scleritised section of the aedeagus. It would be easy when removing hemidactylla's aedeagus from the abdomen for the vessica to slide out and be lost, thus creating the impression that it has no cornuti. The shape of the tip of the aedeagus seems to differ too - more squared-off on hemidactylella and pointed in honoratella. Note that in honoratella the appearance of the tip changes depending on the angle - either with a triangular central point or, if turned through 90 degrees, a point at one side (suggestive to me of Caloptilia semifacscia). I think there's also a subtle difference in the shape of the valvae but I need to see more examples to firm that one up. The first four genitalia photos below are taken before setting, the aedeagus shots taken at different orientations; the last three are taken after setting with the cover slip placed.

male Pale Maple Stilt Caloptilia honoratella showing genitalia, Lingwood (Norfolk, UK), 28th March 2022

I didn't have to wait much longer to catch them myself for the first time here.

male Pale Maple Stilt Caloptilia honoratella showing genitalia, North Elmham (Norfolk, UK), 11th July 2022

female Pale Maple Stilt Caloptilia honoratella, North Elmham (Norfolk, UK), 12th July 2022

male Pale Maple Stilt Caloptilia honoratella, North Elmham (Norfolk, UK), 5th April 2024