Key to larvae of 10 cytoforms in the S. ceylonicum group in Thailand *

(Figs. 9–10)

1 Postgenal cleft (Fig. 9 E–G)> 5.0 x as long as postgenal bridge, reaching or approaching hypostoma.....2

- Postgenal cleft (Fig. 9 A–D, H–J) <5.0 x as long as postgenal bridge, leaving moderate length of postge- nal bridge.....................................................................................................................................................4

2 Abdomen without reddish-brown markings dorsally; abdominal setae unbranched (Fig. 10 A)................... ................................................................................................................................................. nr. asakoae 4

- Abdomen with reddish-brown markings dorsally; abdominal setae branched (Fig. 10 B)..........................3

3 Abdomen yellowish ............................................................................................................. trangense n. sp.

- Abdomen yellowish except segments I–IV greenish ......................................................................... sheilae

4 Abdomen yellowish except segments I and IV greenish.............................................................................5

- Abdomen yellowish except segments I–III or I–IV greenish......................................................................6

5 Postgenal cleft (Fig. 9 J) subequal to or shorter than postgenal bridge. ................................... inthanonense

- Postgenal cleft about twice as long as postgenal bridge (Fig. 9 D).......................................... nr. asakoae 3

6 Abdomen yellowish except segments I–III greenish...................................................................................7

- Abdomen yellowish except segments I–IV greenish...................................................................................8

7 Abdominal segment V with reddish-brown transverse band dorsally ................................... curtatum n. sp.

- Abdominal segment V without distinct colored band ............................................................. nr. asakoae 2

8 Head spots faint ......................................................................................................................... nr. sheilae 3

- Head spots distinct.......................................................................................................................................9

9 Hypostoma shorter than its greatest width ....................................................................................... asakoae

- Hypostoma nearly as long as its greatest width ............................................................... doisaketense n. sp.