Key to the males of New Caledonian Hydrobiosidae

1 Spurs 0, 4, 4; fore wing R1 simple; crossvein R–M present; abdominal filament well developed; in genitalia, lateral process of proctiger situated proximally on proctiger; filopod slender; parapod present ........................................................ Xanthochorema 2

­ Spurs 2, 4, 4; fore wing R1 distally bifurcated; crossvein R–M absent; abdominal filament absent; in genitalia, lateral process of proctiger situated distally on proctiger; filopod broad; parapod absent ............................................ Apsilochorema caledonicum

2 In genitalia, inferior appendage present ....................................................................... 3

­ In genitalia, inferior appendage absent ........................................................................ 4

3 In genitalia, gonocoxite divided into coxopodite and harpago ... .................. X. celadon

­ In genitalia, gonocoxite not divided into coxopodite and harpago ............... X. caledon

4 In genitalia, parapod divided into equally long dorsal and ventral branches ............... 5

­ In genitalia, parapod simple, but may have small dorsal, trianguloid processes .......... 6

5 In genitalia, parapod with dorsally oriented dorsal branch ........... X. neocaledonia sp.n.

­ In genitalia, parapod with posteriorly oriented dorsal branch ................... X. bifurcatum

6 In genitalia, parapod dorsal margin smooth ................................................. X. paniensis

­ In genitalia, parapod with dorsal, trianguloid processes .......................... X. calcaratum