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(Figs. 4 B, 14 I – J) The existence of undescribed diversity in the Rhizoprionodon acutus species complex complicates identification of the single specimen (SL- 21) of this complex we encountered in the Erinchamman Kovilady market in Point Pedro in the Northern Province. Based on the molecular and morphological data presented by Caira & Jensen (2015), the specimen from Sri Lanka is most similar to R. acutus from the Gulf of Oman, rather than to any of the numbered designations (i. e., Rhizoprionodon cf. acutus 1, Rhizoprionodon cf. acutus 2, and Rhizoprionodon cf. acutus 3) for the three undescribed members of this species complex recognized by Naylor et al. (2012 a). In the tree resulting from our Neighbor-Joining analysis, which included all seven described members of the genus and all three undescribed member of the R. acutus complex, the specimen from Sri Lanka grouped most closely with the reference specimen of R. acutus (MM- 4; JQ 518653) from the Gulf of Oman, differing from this specimen by only 1 bp. In contrast, it differed from our reference specimen of R. cf. acutus 1 from Senegal (SE- 219; JQ 518652) by 10 bp, from our reference specimen of R. cf. acutus 2 from Australia (AU- 120; JQ 518649) by 13 bp, and from our reference specimen of R. cf. acutus 3 from Malaysian Borneo (HBO- 30; JQ 519100) by 18 bp. This name is in current use for this species in Sri Lanka (e. g., De Silva 1984 – 1985, 2006, 2015; De Bruin et al. 1995; Joseph 1999).