Key to the waterfall-inhabiting* Naucoridae of southern India and Sri Lanka

1. Dense fringe of long hairs along posterior margin of abdomen (Fig. 3). Hemelytra without linear series of short, stout hairs. Male with one protarsal segment (Figs. 1, 2)......................................... Pogonocaudina indica n. sp.

1'. Long hairs along posterior margin of abdomen scattered or in small clusters. Hemelytra with linear series of short, stout hairs. Male with two protarsal segments........................................................... Diaphorocoris ... 2

2. Length 9 – 10 mm ........................................................ Diaphorocoris dubreuili Montandon

2'. Length 7 – 8 mm ..................................................................................... 3

3. Thoracic and abdominal sterna dark brown to black, except yellowish lateral band; metaxyphus about as long as wide (Fig. 16). Embolium with marginal row of short, black spines (Fig. 13). Scutellum without glabrous tubercles................................................................................................ Diaphorocoris kiliyur n. sp.

3' Thoracic and abdominal sterna medium to reddish brown, except yellowish lateral band; metaxyphus 1.5 – 2.0 times as long as wide (Fig. 15). Embolium with marginal row of stout, brown, peg-like spines (Figs. 11, 14). Scutellum with glabrous tubercles.................................................................................................... 4

4. Pronotum broadly sunken at midline lower than rounded ridge of anterior margin; surface with normal convexity adjacent to lateral hyperoche of head. Embolium with dark coloration immediately anterior to the distal mesal incursion of the yellowishwhite marginal coloration extending only halfway from embolar suture to lateral margin, separated from margin by distance of ca. 5 times the length of a marginal spine (Fig. 14)............................. Diaphorocoris punctatissimus (Kirby)

4'. Pronotum with slight depression at midline but not sunken below anterior margin; surface with flattened area adjacent to lateral hyperoche of head. Embolium with dark coloration immediately anterior to the distal mesal incursion of the yellowish-white marginal coloration extending close to the margin, separated from margin by distance of 2–3 times the length of a marginal spine (Fig. 11)............................................................ Diaphorocoris arunachalami n. sp.