Duplex horakae is a species of moth in the family Erebidae, first described by Michael Fibiger in 2010. It belongs to the genus Duplex, which comprises small moths formerly placed in the family Micronoctuidae before that group was subsumed into Erebidae.
Distribution: The species is known from northern Australia, specifically the northern parts of the Northern Territory and the north-eastern part of Western Australia.
Description: The wingspan of Duplex horakae is 7.5–9 mm. The forewings are short and broad, colored grey or blackish grey. The crosslines are all present and black; the antemedial line is prominent and sharply angled subcostally, and the subterminal line is prominent and waved.
Taxonomy: The species was originally placed within the family Micronoctuidae, but subsequent taxonomic revisions have moved it to the subfamily Hypenodinae within Erebidae. The specific epithet horakae honors a person (likely a researcher or collector), following the common taxonomic practice of naming species after individuals.
Differential diagnosis: Duplex horakae differs from other Duplex species in its short and broad forewing coloration, the shape of the ampulla and antrum (structures in the male and female genitalia, respectively), and the length of the ductus bursae (a structure in the female reproductive system). It is the smallest known Australian species in the genus.
