Type species. Diastylis longimana Sars, 1865 by subsequent designation (Lomakina, 1958).
Diagnosis. Female and subadult male. Carapace globular, pleon narrow. Pereopods 3–4 with rudimentary exopods in female. Telson short with no more than 2 pairs of lateral setae.
Adult male. Antennule greatly expanded, with multitudes of setae on peduncle article 3. Antenna not extending to telson.
Remarks. There are very few species of Leptostylis or the closely related Austroleptostylis in Australian and New Zealand waters.
New Zealand species. Leptostylis wisniewskiae n. sp., L. zealandiensis n. sp.