Phylomitogenomics reconfirm the phylogenetic position of the genus Metaplax inferred from the two grapsid crabs (Decapoda: Brachyura: Grapsoidea)

Abstract

Two new complete mitogenomes of the grapsids, Metaplax longipes Stimpson, 1858 and Nanosesarma minutum (De Man, 1887) were sequenced using next-generation sequencing (NGS). By analyzing a combination of 75 Brachyura taxa, our phylomitogenomic inferences suggested that Metaplax crab seperated earlier from the sesarmid crabs and closely related to the varunids with respect to Nanosesarma crab. It reconfirmed that the Metaplax should be removed from the Sesarmidae and assinged to the Varunidae. Additional mitogenomic comparisons including gene rearrangement and genomic organization were conducted among the 33 taxa of Grapsoidea and Ocypodoidea, and a shared rearrangement pattern between Metaplax longipes and the varunids were recovered, which also strongly supported the inference for the phylogenetic position of the Metaplax.

Review of the mudflat varunid crab genus Metaplax (Crustacea, Brachyura, Varunidae) from East Asia and northern Vietnam

“…Monophyly of Metaplax has not yet been confirmed. Moreover, despite various recent research effort employing even complete mitochondrial sequences, the sister group of Metaplax remains unclear (Kitaura et al 2002; Chen et al 2019; Liu et al 2019), which is probably due to the limited genera sampled in phylogenetic analyses.…”

“…Indo-West Pacific varunid crabs of the genus Metaplax H. Milne Edwards, 1852 commonly inhabit sheltered shores with silty muddy substrate often near or under shades of mangroves in tropical and subtropical regions. While some studies have reported on various biological aspects of selected species (e.g., Macnae 1963; Beinlich and Polivka 1989; Chakraborty and Choudhury 1994), the phylogenetic position of this group within the Thoracotremata remains obscure due to limited taxon sampling (see Kitaura et al 2002; Chen et al 2019; Liu et al 2019).…”

Crab in amber reveals an early colonization of nonmarine environments during the Cretaceous

“…Recent phylogenomic studies indicate that Potamidae, a freshwater family of heterotreme crabs, are sister to Thoracotremata—the group that includes the true land crabs and allies—rather than being closer to other freshwater heterotremes (see also Fig. 5 ) ( 10 , 66 , 67 ). Our results support the paraphyly of “Heterotremata,” with thoracotremes nested within heterotremes ( Fig.…”

“…This raises the question of the relationships between total-group Eubrachyura and their closest noneubrachyuran relatives, e.g., the crown podotremes Raninoida and Cyclodorippoida that, together with Eubrachyura, form a clade well supported by morphological, molecular, and phylogenomic studies (Fig. 5) [e.g., (7,8,(66)(67)(68)]. As such, the earliest eubrachyurans may have diverged from a common podotreme-like ancestor shared with raninoids and cyclodorippoids but not with other podotremes such as homoloids, dromioids, and homolodromioids.…”

Varying colour pattern, yet genetically similar: Pebble Crab Seulocia vittata (Stimpson, 1858) (Brachyura: Leucosiidae) from the southeastern coast of India

“…understanding the evolutionary perspectives of marine brachyuran crabs (Hultgren & Stachowicz 2008;Lai et al 2013;Fratini et al 2018;Mantelatto et al 2018;Chen et al 2019). The integrative approach of both morphological and molecular analyses offers robust information not only on the taxonomic ambiguity of the species, including cryptic species (Baeza & Prakash 2019) but also in the monitoring of commercial crabs for seafood safety (Rath et al 2018).…”