Clarifying the taxonomic status of Merluccius spp. in the northeastern Pacific: a combined morphological and molecular approach

Abstract

The taxonomic status of hake (Merluccius spp.) in the northeastern Pacific is unclear. Hakes in this region are Merluccius productus, M. angustimanus, M. hernandezi, and a morphotype known as dwarf hake. Of these, only the first two species are currently valid. Descriptions in previous studies have been limited by overlapping morphological characteristic, lack of biological material, and limited numbers of sampling localities. To clarify their taxonomy, 461 hake were obtained from eight localities along the North American coast for morphological and mitochondrial DNA sequence analyses (cytochrome b, cytochrome c oxidase subunit I, and 16S ribosomal rDNA). Morphological and molecular analyses suggest that hake in this region represent a continuum of a single species with some levels of morphological and genetic intra-specific variation. In light of these results, we propose that M. productus is the only species of hake present along the North American and northern Central American coast.

New tools (DNA barcoding), old hypothesis: the case of the taxonomic identity of the Argentine hakes (Actinopterygii: Merluccius)

“…Furthermore, the BIN system is built on prior studies that have established that most animal species show <2% intraspecific variation in coI , but >4% divergence from their nearest neighbour (Ratnasingham & Hebert, ). The within‐BIN maximum K2P distances were <2% for the present study (1·57 for BOLD:AAB5094 and 1·16 for BOLD:AAA8613), agreeing with previous studies that revealed low divergences between M. angustimanus , M. gayi and M. productus (Silva‐Segundo et al , ) and between M. merluccius and M. senegalensis (Quinteiro et al , ; Campo et al , ). On the other hand, the BIN analysis recognized two taxonomic units in the sequences studied here, which agree with the current taxonomic classification.…”

“…). Previous DNA mitochondrial studies [cytochrome b ( cytb ), control region and 16S rDNA] also pointed out high genetic distances between M. hubbsi and M. australis (Tamura‐Nei: 7·8% in Quinteiro et al (); K2P: 4·2% in Campo et al (); Tamura‐Nei: 1·7 to 4·8% in Silva‐Segundo et al ()).…”

“…EU074470 and EU074473), differing by one nucleotide each and other haplotype shared by the remaining specimens. Accordingly, low divergences have been found between specimens in both species by means of other DNA mitochondrial sequences analyses [Quinteiro et al , (Tamura‐Nei: 0·5%); Silva‐Segundo et al , (Tamura‐Nei: 0·2%)] and trough nuclear markers (Roldán et al , ; Grant & Leslie, ; Roldán & Pla, ).…”

Preferential distribution of fish larvae in the California Current System: Time, space, and temperature

“…Nonetheless, this species is not significantly distributed in the surrounding areas between PE‐BSV (Funes‐Rodríguez et al., ; Moser et al., ), which could imply the distribution of two spawning stocks in the CCS (Bailey, Francis, & Stevens, ; Funes‐Rodríguez et al., ). However, genetic studies on M. productus suggested a lesser degree of intra‐specific variation between Washington and Costa Rica (Silva‐Segundo et al., ).…”

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“…Distribution: New South Wales and Victoria (Day et al, 1995), Poland (Poniewozik, 2009), Czech Republic (Kocarkova et al, 2004 and Singapore (Pham et al, 2011). Distribution: Romania (Caraus, 2012), Spain (Alvárez-Cobelas, 1984), Mexico (Valadez et al, 2010), Brazil (Alves-da-Silva and Menezes, 2010), Sierra Leone (Alfinito, 2011), China (Hu and Wei, 2006) and Taiwan (Shao, 2009 Starmach (1983;page 192, figure 388) Description: Cells longitudinally oval, 87-102 µm long, 42-46 µm, wide, narrowed at posterior end into long appendix ca. 31-33 µm long; periplast longitudinally striated, paramylon grains ring-shaped, one large located in cell centre, smaller located in lower part of cell; chloroplasts small, without pyrenoids ( Figure 2i).…”