Integrative taxonomy–based discovery of Dussumieria modakandai sp. nov. from India

Abstract

This study is based on integrative taxonomy and reports a new fish species Dussumieria modakandai sp. nov. from India. The new species differs from three valid species within the genus by a combination of characters such as longer maxilla (9.1%-9.9% standard length vs. 8.7% in Dussumieria elopsoides, 6.3%-8.5% in Dussumieria acuta) and one or two rows of small conical teeth on palatine (vs. several rows in D. elopsoides and Dussumieria albulina). It also differs by the absence of longitudinal striae on the posterior side of body scales (vs. presence in D. acuta and D. albulina) and the absence of parasphenoid teeth (vs. presence in D. acuta). The maxilla length of D. modakandai sp. nov. is greater than snout length, which distinguishes it from other congeners. The multivariate analysis of morphometric characters using PCA differentiated the new species from D. elopsoides and D. acuta samples collected in this study. The molecular analysis, based on cytochrome c oxidase I, distinguished the new species from D. acuta, D. albulina and D. elopsoides with a high genetic distance of 13.73%, 12.22% and 12.74%, respectively. The maximum-likelihood phylogenetic tree and automatic barcode gap discovery analysis showed the existence of six putative species in Dussumieria. Even the exhaustive sub-clade formation within species and high intra-species genetic distance in D. acuta (1.59) and D. modakandai (1.95) indicate the possibility of a few more cryptic species. This warrants comprehensive sample collection across the distribution range and integrative taxonomic study of the genus Dussumieria.

Resurrection and redescriptions of nominal species previously regarded as synonyms of Thrissina mystax (Bloch and Schneider, 1801) (Teleostei: Clupeiformes: Engraulidae)

“…T. valenciennesi further differs from T. mystax in having a shorter maxilla (24.4%–27.9% of SL in T. valenciennesi vs. 28.1%–31.1% in T. mystax ; Figure 7d) and a lower number of 4TGR (14–17 [rarely 18] vs. 19–22 [18]; Figure 6d). In fact, the gill raker numbers on each gill arch are an important diagnostic character in various clupeiform fishes (Agostinho et al, 2022; Gangan et al, 2020; Kimura et al, 2009; Singh et al, 2021; Whitehead et al, 1988), and even 4TGR numbers (gill rakers on innermost gill arch) can be a distinguishing character in some cases (Hata et al, 2022b; Hata, Lavoué, Bogorodsky, et al, 2023; Hata, Lavoué, Chunthanawong, & Motomura, 2023). However, it appears to be rare that two apparently closely related species differ significantly in 4TGR number, even though no differences exist in GR numbers on other gill arches.…”