Acanthopagrus (Munro, 1948)

Hasan, Mohammad Eusuf, Durand, Jean-Dominique & Iwatsuki, Yukio, 2020, Acanthopagrus datnia (Hamilton, 1822), a senior synonym of Acanthopagrus longispinnis (Valenciennes, 1830) (Perciformes: Sparidae), Zootaxa 4750 (2), pp. 151-181 : 175-176

Acanthopagrus spp. and their genetic relationship with Sparidentex

The molecular phylogeny of the family Sparidae (including Acanthopagrus and Sparidentex ) was established by Orrell et al. (2002) and Orrell & Carpenter (2004), based on mitochondrial 16S rRNA and cytochrome b sequences respectively. Chiba et al. (2009), using cytochrome b gene, subsequently added additional species ( A. australis , A. butcheri , A. chinshira , A. latus , A. pacificus , A. schlegelii , A. sivicolus , A. taiwanensis , and A. cf pacificus [as Acanthopagrus sp.], and demonstrated a monophyletic subgroup of B-6 ( Figs. 3–4 of Chiba et al. 2009). The monophyly of these species is also evident in our 16S rRNA and CO1 trees along with other congeners including A. berda , A. bifasciatus , A. datnia , A. latus , A. australis , A. sheim , and A morrisoni . No genetic separation was observed in Acanthopagrus berda between the Bay of Bengal and Arabian Sea.

Present phylogenetic analyses confirm the paraphyletic position of Sparidentex hasta with Acanthopagrus species previously highlighted by Chiba et al. (2009) using cytochrome b polymorphisms. Previous phylogenetic studies stressed a close phylogenetic relationship of S. hasta with Acanthopagrus , but using only one representative of this last genus it was not possible to demonstrate its paraphyly ( Orrell et al. 2002, Orrell & Carpenter 2004, Chiba et al. 2009). By including some specimens of Acanthopagrus arabicus in the present study, we were able to demonstrate a sister relationship between this species and Sparidentex hasta , two species that have almost the same distribution range in the Persian Gulf and Arabian Sea.

The above results appear to argue for the synonymy of the genus Sparidentex with Acanthopagrus . Despite having differences in teeth pattern (outer series of conical and inner villiform teeth in Sparidentex vs inner series of molariform teeth in Acanthopagrus ), the overall shape and colouration of body and fins in Sparidentex resemble that of Acanthopagrus ( Munro 1948) . The upper jaw morphology in Sparidentex hasta resembles that of Acanthopagrus (K. Carpenter, cited in Orrell et al. 2002), and the dorsal fin, appearing alternately strong and weak on each side, equates with Acanthopagrus (Bauchot and Smith 1984) . The presence of conical and villiform teeth in S. hasta , therefore, may be the result of a convergent evolution and not a phylogenetic signal. Further phylogenetic and morphometric analysis among Acanthopagrus spp. and Sparidentex spp. will help to clarify the validity of this classification ( Chiba et al. 2009, Y. Iwatsuki & K. E. Carpenter pers. comm.). A complete molecular analysis of all 20 known species of Acanthopagrus using both mitochondrial and nuclear genes will help to clarify the phylogenetic relationships within Acanthopagrus and between Acanthopagrus and Sparidentex .

Figures

FIGURE 3. Maximum likelihood tree constructed using mitochondrial CO1 depicting phylogenetic relationship among selected Acanthopagrus spp. including Acanthopagrus datnia and A. berda from Bay of Bengal, and Sparidentex hasta. Details of specimen data and GenBank accession numbers are provided in Table 1. Check images of some specimen in Fig. 8. Note—all Acanthopagrus datnia specimens with variable body shape (■, slender SL/BD>2.4, or O, deeper<2.4), and variable length of 2AS (above or below 21% SL) in one single clade.

FIGURE 4. Maximum likelihood tree constructed using (A) mitochondrial 16S rRNA gene for Acanthopagrus datnia (n=10) and nine other congeners and Sparidentex hasta, and (B) nuclear RAG-1 gene (n=16), for Acanthopagrus datnia and three other congeners, and Sparidentex hasta. Note—all Acanthopagrus datnia specimens with variable body shape (■, slender SL/ BD>2.4, or O, deeper<2.4), and variable length of 2AS (above or below 21% SL) in one single clade. Details of specimen data and GenBank accession numbers are provided in Table 1. Check images of some specimen in Fig. 8.