A New Species of Thrissina from the Andaman Sea and Re-assessment of the Taxonomic Status of Thrissina cuvierii (Swainson, 1839) and Thrissina malabarica (Bloch, 1795) (Teleostei: Clupeiformes: Engraulidae: Coiliinae)
Examination of the original description of Thrissina malabarica (Bloch, 1795), a name previously applied to an Indian Ocean species with a distinctly deep body, revealed that the former nominal species was actually a senior synonym of Thrissina hamiltonii (Gray, 1835), a slender-bodied Indo-West Pacific species. The applicable name for the species previously treated as T. malabarica is Thrissina cuvierii (Swainson, 1839). To stabilize the taxonomic status of these three nominal species, a neotype for T. cuvierii is designated. In addition, Thrissina aurora, new species, is described from a specimen collected from the Andaman Sea near Phuket, Thailand. Although both the new species and T. cuvierii share a deep body, the former is distinguished by lower counts of gill rakers and anal-fin rays than the latter. The mitochondrial cytochrome oxidase I (COI) haplotype network of 11 specimens of T. cuvierii and three specimens (including the holotype) of T. aurora, new species, revealed 22 nucleotide differences between the two species, corresponding to 3.4% mean uncorrected genetic distance.
Non-type specimen of Thrissina cuvierii: KAUM-I. 68984, 165.7 mm SL, Sindh, Pakistan, in (A) fresh condition and (B) preserved condition. (C) Neotype of Thryssa cuvierii, BMNH 1868.10.27.27, female, 159.1 mm SL, Chennai, Tamil Nadu State, India.
Distributional records of Thrissina cuvierii (red circles) and T. aurora, new species (blue triangles). Solid and white symbols indicate locations based on specimen examination and solely on molecular evidence, respectively.
Median-joining network showing relationships among 14 mitochondrial DNA (cytochrome oxidase subunit I) haplotypes of Thrissina cuvierii (red circles) and Thrissina aurora, new species (blue circles), within the central Indo-West Pacific region (Fig. 2 shows geographical origins of specimens used in the analysis). Network reconstructed using PopART, each circle representing a unique haplotype, with size proportional to sample frequency. Each crossbar represents a single nucleotide substitution.
Illustrations of specimens of the genus Thrissina. (A) “Poorwa” from Russell (1802: pl. 194); (B) Clupea malabarica from Bloch (1795: pl. 432); (C) “Engraulis malabaricus” (Thrissina cuvierii in this study) from Cuvier and Valenciennes (1847: pl. 609; source: Biodiversity Heritage Library).
Holotype of Thrissina aurora, new species, THNHM-F 021939, 146.7 mm SL, Phuket, Thailand. (A) Fresh condition; (B) preserved condition.
Relationships of total gill raker numbers (TGR) to standard length in Thrissina cuvierii (red circles) and T. aurora, new species (blue triangle). (A) First gill arch (1GA); (B) second gill arch (2GA); (C) third gill arch (3GA); and (D) fourth gill arch (4GA).
Relationships (as % of standard length; SL) of (A) snout tip to pectoral-fin insertion (B) dorsal-fin base length, (C) caudal-peduncle length, (D) caudal-peduncle depth, (E) distance between origins of dorsal and anal fins (D–A), and (F) snout length to standard length in Thrissina cuvierii (red circles) and T. aurora, new species (blue triangle).
Contributor Notes
Associate Editor: M. T. Craig.