Elachista caliginosa is a species of moth in the family Elachistidae.
Taxonomy Elachista caliginosa was described by the Italian entomologist Umberto Parenti in 1983. It belongs to the genus Elachista, subfamily Elachistinae, within the family Elachistidae (superfamily Gelechioidea). It is a member of the Elachista praelineata species group.
Distribution The species is found in Japan (Honshu, Tsushima Island) and the Russian Far East (Primorsky Krai). Records also exist from Nagano Prefecture in central Japan.
Description The forewing length is 2.5–3 mm in males and 2.7–3.2 mm in females. The forewings are dark grey-brownish with silver-whitish markings: an outwards-bent transverse fascia beyond the one-third point (often interrupted around the fold), a narrow sub-triangular spot on the costa at three-quarters, and a smaller tornal spot opposite the costal spot. Female specimens are generally darker, with forewing markings that are larger and more distinct than those of males. The species is sexually dimorphic in coloration.
Biology The larvae are leaf-miners, feeding on grasses (Poaceae), including Eccoilopus cotulifer and possibly Spodiopogon sibiricus. The mine is a full-depth, linear gallery extending almost straight toward the leaf apex. The full-grown larva leaves the mine and pupates in a cocoon made of sparse silk web, typically on the upper side of the basal part of the mined leaf. The pupa is attached to the surface by a silk-girdle surrounding its abdomen and the cremaster. The species is thought to have more than one generation per year and likely hibernates as a pupa.
Female description The female of Elachista caliginosa was described for the first time by Sugisima in 2005, over two decades after the original species description by Parenti. The female genitalia are characterized by a deep bowl-shaped antrum lined with coarse spines and a corpus bursae bearing a cross-shaped signum.
Similar species Elachista caliginosa is closely related to Elachista fasciocaliginosa, described by Sugisima in 2005, from which it differs primarily in wing markings: E. fasciocaliginosa has two distinct silvery fasciae traversing the wing, whereas E. caliginosa has more blurred and interrupted markings.
