Sorry for the late responce but I'm on family-visit in Germany and don't have any literature by hand to make afundated comment. As soon as I'm home again I will spend some time in Scimitar-babbler taxonomy !
Up to date taxonomy ( 2011 )
• Pomatorhinus erythrocnemis is split into several species as follows: 1) Spot-breasted Scimitar-Babbler Pomatorhinus mcclellandi of Assam India and w Myanmar; 2) Black-streaked Scimitar-Babbler Pomatorhinus gravivox of s and sw China, n Vietnam, Laos and Myanmar; 3) Gray-sided Scimitar-Babbler Pomatorhinus swinhoei of e and se China; 4) Black-necklaced Scimitar-Babbler Pomatorhinus erythrocnemis of Taiwan.
• Sri Lanka Scimitar-Babbler Pomatorhinus melanurus, a Sri Lanka endemic, is split from the more widespread Indian Scimitar-Babbler Pomatorhinus horsfieldii
• Taiwan Scimitar-Babbler Pomatorhinus musicus, a Taiwan endemic, is split from the more widespread Streak-breasted Scimitar-Babbler Pomatorhinus ruficollis.
MacKinnon's field guide to China is well known for containing quite a few inaccuracies and was also published years before the split of the P. erythrogenys complex. Collar's article on this and other babbler splits can be downloaded freely on the Oriental Bird Club's webpage, but it is not exactly pleasure reading unless you're very interested in Asian bird taxonomy
Anyhow, while I do understand the confusion due to all the taxonomic changes, the pattern of this bird leaves no doubts to its identification.
P. erythrogenys: Faint black malar streak, rufescent flanks, no distinct black spotting to chest.
P. mcclellandii: Narrow black malar streak, brown flanks, spotting to chest.
P. swinhoei: Faint black malar streak, gray flanks, spotting on chest.
P. erythrocnemis: Resembles following, but with rufescent back contrasting clearly with gray-brown crown and ear coverts.
P. gravivox: See description in post #11.
