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Abstract

Recent work of Japanese colleagues suggests that colour patterns used are insufficient to distinguish Japanese species of Neoperla . Distinctive structural details of N. geniculata (a species of the montivaga -group of Zwick, 1983, Spixiana 6: 187) are therefore here described. Front wing 15-17 mm long; Rs with 4 branches. Ocelli small, 1.5 diameters apart. Yellow; a large lighter than rest) dark brown. Pronotum with brown edges and wide median brown band continued on mesonotum. Antennae brown, base light. Legs yellow except dark brown tips of femora, bases and tips of tibiae, and tarsi. Sternite 8 with dark Y-shaped mark ending in a small pointed or indistinctly bilobed projection with shorter pilosity than rest of segment. Vagina very large, elongate. Its lower and posterior portions apparently very extensible and composed of irregularly wrinkled soft folds.