This is the information I have on the two species:
AMPHIPRION SEBAE (BLEEKER, 1853)
Sebae Anemonefish
Original description: As Amphiprion sebae, from specimens collected at Java (an island of Indonesia)
Colour features and size: Dark brown to blackish with two white bars, the mid-body bar slanting slightly backwards and extending onto rear part of dorsal fin; snout, breast, and belly often yellow orange; tail yellow or orange. Maximum length about 140 mm.
Similar species: Amphiprion polymnus (Indo-Australian Archipelago to Japan) is similar, but has a distinctive dark, wedge-shaped mark covering most of the tail.
Host anemone species: Stichodactyla haddoni.
Melanistic variation: Some individuals are entirely dark brown to blackish on the body (except for white bars), lacking yellow-orange colour on the snout, breast, and belly. It is not known if the variation is associated with a particular anemone host.
Distribution: Northern Indian Ocean including Java, Sumatra, Andaman Islands, India, Sri Lanka, Maldive Islands, and southern Arabian Peninsula.
AMPHIPRION CLARKII (BENNETT, 1830)
Clark's Anemonefish
Original description: As Anthias clarkii, from specimens collected at Ceylon (now Sri Lanka)
Colour features and size: Usually black with variable amount of orange on head, ventral parts, and fins; three white bars -- on head, body, base of caudal fin; transition between darker body and bar across caudal fin base usually abrupt; caudal fin usually white or white with yellow edges (males), but sometimes yellow; juveniles from all areas and adults from Vanuatu and New Caledonia may be mostly or entirely orange-yellow with only two anterior white bars. Maximum length about 140 mm.
Similar species: Amphiprion latifasciatus (Madagascar and Comoro Islands) lacks a white bar on the caudal fin base and its tail is forked. Amphiprion allardi (East Africa), A. akindynos (Great Barrier Reef - Coral Sea), and A. chagosensis have a narrower mid-body bar and lack the sharp demarcation between white on the caudal fin base and dark of the body. Amphiprion chrysogaster (Mauritius), A. fuscocaudatus (Seychelles), and A. tricinctus (Marshall Islands) have three white bars, but the caudal fin is dark.
Host anemone species: Cryptodendrum adhaesivum; Entacmaea quadricolor; Heteractis aurora; H. crispa; H. magnifica, H. malu; Macrodactyla doreensis; Stichodactyla gigantea; S. haddoni; S. mertensii.
Melanistic variation: Fish that live with Stichodactyla mertensii are frequently black except for pale snout, white bars, and yellow or white tail.
Distribution: Amphiprion clarkii is the most widely distributed anemonefish, ranging from the islands of Micronesia and Melanesia in the western Pacific to the Persian Gulf, and from Australia to Japan.
I think you will find this link of great interest:
http://www.nhm.ku.edu/inverts/ebooks/intro.html
Charles