Kentish Plover Charadrius alexandrinus
Field observations in south-east Asia and subsequent museum comparisons have documented consistent differences between Kentish Plover and White-faced Plover in plumage, behaviour and habitat preference, and have clarified the nomenclature of east Asian Kentish Plovers (Bakewell & Kennedy 2008, Kennedy et al. 2008; see also Rheindt et al. 2011). White-faced Plover differs from Kentish Plover by its larger and heavier bill with a pale base to the lower mandible (black in Kentish Plover), pale pinkish-grey legs (usually dark in Kentish Plover), light sandy-brown upperparts (cold dark brown in Kentish Plover) and a longer and more conspicuous wing bar. The two plovers also show significant differences in bill, wing and tarsus length (distinctly longer in White-faced; Kennedy et al. 2008, Sadanandan et al. 2019, Wang et al. 2019a).
Mitochondrial DNA sequences shows two major clusters along the chinese coast, one corrresponding to northern birds (Kentish Plover) and the other to southern birds (White-faced Plover) (Wang et al. 2019a; see also Wang et al. 2019b). Mitochondrial DNA of the two taxa is almost reciprocally monophyletic, with a very small number of mismatches (Wang et al. 2019a). Evidence from microsatellites (Wang et al. 2019a), autosomal and Z-linked nuclear DNA sequences (Wang et al. 2019a), and genome-wide SNPs (Sadanandan et al 2019, Wang et al. 2019b) indicates the existence of two well-defined genomic clusters corresponding to Kentish Plover and White-faced Plover. Genomic divisions between White-faced and Kentish Plovers from the same areas in Fujian Province were much deeper than those between members of opposing ends of the Kentish Plover continental distribution (Spain and eastern Asia; Sadanandan et al. 2019). Overall, the molecular data indicate limited hybridization and a narrow contact zone in eastern China suggesting that gene flow, while present, is rare between Kentish and White-faced Plovers (Sadanandan et al. 2019, Wang et al. 2019a).
In addition, Kentish Plover and White-faced Plover are ecological divergent, as shown by significant differences in stable isotopes and environmental niches (Wang et al. 2019a).

The combination of (1) several plumage differences; (2) significant morphometric differences; (3) near-monophyly of mitochondrial DNA sequences; significant differences in (4) microsatellite data, (5) autosomal and (6) Z-linked DNA sequence data; ecological differences, as documented by analyses of (7) stable isotopes, and (8) ecological niche modelling; (9) a very small number of hybrids, and lack of (broad) hybrid zone, provides compelling evidence that White-faced Plover is best treated as a full species (Charadrius dealbatus).

A recent integrative taxonomic study showed that the South Asian population (C. a. seebohmi) differs from other populations of Kentish Plover in (i) size (seebohmi is smaller than Kentish Plover and White-faced Plover, and all three taxa showed no overlap in multivariate analysis), (ii) moulting pattern (seebohmi moults into breeding plumage during September or October, unlike Kentish Plover which moults into breeding plumage from January to March), (iii) coloration of the cap in adult breeding males (rufous cap lacking in seebohmi, which has rufous buff mixed in with their paler cap; cap rufous in Kentish Plover); (iv) completeness of breast patches (incomplete in seebohmi; complete in Kentish Plover); (v) completeness of dark lores (incomplete in seebohmi but darker in breeding plumage; complete in Kentish); and (vi) leg colour (dark grey in both sexes in seebohmi; black in Kentish) (Niroshan et al. 2023). Analysis of mitochondrial, sex-linked and autosomal microsatellite markers from 378 individuals showed that seebohmi is distinct from both Kentish Plover and White-faced Plover (Niroshan et al. 2023). Phylogenetic analysis of mitochondrial, sex-linked and autosomal DNA sequences showed that seebohmi is the sister-taxon of Kentish Plover and White-faced Plover (Niroshan et al. 2023). The combined data provide compelling evidence that the South Asian population is best treated as a full species (Charadrius seebohmi), which Niroshan et al. (2023) proposed to call Hanuman Plover.

• Hanuman Plover Charadrius seebohmi (monotypic, with leggei Whistler & Kinnear, 1937 as a synonym)
• Kentish Plover Charadrius alexandrinus (polytypic, with subspecies alexandrinus and nihonensis)
• White-faced Plover Charadrius dealbatus (monotypic).

Bakewell, D.N. & Kennerley, P.R. 2008. Field characteristics and distribution of an overlooked Charadrius plover from South-East Asia. BirdingASIA 9: 46–57.

Kennerley, P.R., Bakewell, D.N. & Round, P.D. 2008. Rediscovery of a long-lost Charadrius plover from South-East Asia. Forktail 24: 63–79.

Niroshan, J.J., Liu, Y., Martinez, J., Que, P., Wei, C., Weerakkody, S., Panagoda, G., Weerasena, J., Thasun Amarasinghe, A.A., Székely, T., Bond, A.L. & Seneviratne, S.S. 2023. Systematic revision of the ‘diminutive’ Kentish Plover (Charadriidae: Charadrius) with the resurrection of Charadrius seebohmi based on phenotypic and genetic analyses. Ibis 165: 1296–1317.

Rheindt, F.E., Székely, T., Edwards, S.V., Lee, P.L.M., Burke, T., Kennerley, P.R., Bakewell, D.N., Alrashidi, M., Kosztolányi, A., Weston, M.A., Liu, W.-T., Lei, W.-P., Shigeta, Y., Javed, S., Zefania, S. & Küpper, C. 2011. Conflict between genetic and phenotypic differentiation: the evolutionary history of a ‘lost and rediscovered’ shorebird. PLoS ONE 6(11): e26995.

Sadanandan, K.R., Küpper, C., Low, G.W., Yao, C.T., Li, Y., Xu, T., Rheindt, F.E. & Wu, S. 2019. Population divergence and gene flow in two East Asian shorebirds on the verge of speciation. Scientific Reports 9: 8546.

Wang, X., Maher, K. H., Zhang, N., Que, P., Zheng, C., Liu, S., Wang, B, Huang, Q, Chen, D, Yang, X, Zhang, Z, Székely, T, Urrutia, AO & Liu, Y 2019b. Demographic histories and genome-wide patterns of divergence in incipient species of shorebirds. Frontiers in Genetics 10, 919.

Wang, X., Que, P., Heckel, G., Hu, J., Zhang, X., Chiang, C. Y., Zhang, N, Huang, Q, Liu, S, Martinez, J, Pagani-Núñez, E, Dingle, C, Leung, YY, Székely, T, Zhang, Z & Liu, Y 2019a. Genetic, phenotypic and ecological differentiation suggests incipient speciation in two Charadrius plovers along the Chinese coast. BMC Evolutionary Biology 19, 135.