Soleoidea

Campbell, Matthew A., Chen, Wei-Jen, Chanet, Bruno, Chen, Jhen-Nien & Lee, Mao-Ying, 2019, Origins and relationships of the Pleuronectoidei: Molecular and morphological analysis of living and fossil taxa, Zoologica Scripta 48 (5), pp. 640-656 : 650

4.4 | Soleoidea

The third superfamily in Pleuronectoidei is composed of eight families in this study and its monophyly is well supported (Figure 1, BS = 82%, Figure 2, PP = 0.97). There is weak support in the ML analysis (Figure 1, BS = 35%) and moderate support in the Bayesian combined approach (Figure 2, PP = 0.63) for a monophyletic group of Achiridae , Paralichthodidae , Rhombosoleidae and Achiropsettidae and Numidiopleura enigmatica †. This study includes representation of Achiridae , Paralichthodidae , the two divergent lineages of Rhombosoleidae , and Achiropsettidae for the first time to our knowledge in a phylogenetic study and indicates these families in total may form a monophyletic assemblage and Rhombosoleidae is paraphyletic.

Support for arrangements among the families Achiridae , Paralichthodidae , Rhombosoleidae and Achiropsettidae is low, indicated by support values in the ML analysis and a polytomy in the Bayesian combined analysis. The placement of Achiridae as most closely related to Soleidae + Cynoglossidae is well supported from a morphological perspective ( Chanet et al., 2004; Chapleau, 1993; Hoshino, 2001). Nonetheless, here and other studies Achiridae is shown to be closely related to Paralichthodidae , Rhombosoleidae and Achiropsettidae (Betancur‐R., Li, et al., 2013; Harrington et al., 2016), though see Shi et al. (2018) for another placement. Chapleau and Keast (1988) indicate a relationship of ( Samaridae ( Achiridae ( Soleidae + Cynoglossidae ))). It may be possible that this disagreement between placements of Achiridae may result from the particular species examined in anatomical works. Paralichthodidae has held different placements in alternative classification schemes, with integration into Chapleau (1993)’s data set placing it as a family and earliest‐branching member of Soleoidea ( Cooper & Chapleau, 1998b). Our analysis refines placement of the lineage to indicate near relatives of Achiridae , Rhombosoleidae and Achiropsettidae .

Rhombosoleidae is demonstrated to be paraphyletic, with Rhombosolea most closely related to Mancopsetta with maximal support values in the ML analysis (BS = 100%) and moderate support in the Bayesian combined analysis (PP = 0.60). Sampling in mitogenomic studies have not included Oncopterus , but show very high support for a sister relationship between Rhombosoleidae and Achiropsettidae (Campbell, López, et al., 2014; Shi et al., 2018). Oncopterus darwinii is unlike other rhombosoleids as it is found in the Southwest Atlantic and all other rhombosoleids are distributed mainly around Australia and New Zealand ( Nelson, 2006). In our time‐calibrated tree, this monotypic genus is indicated to diverge as an independent lineage 36.51 mya as well. As a resolution for the paraphyly of Rhombosoleidae , we suggest that the monotypic family Oncopteridae be created containing the single species Oncopterus darwinii . Rhombosoleidae then includes nine genera and 18 species: Ammotretis , Azygopus , Colistium , Pelotretis , Peltorhamphus , Psammodiscus , Rhombosolea and Taratretis ( Nelson, 2006). Our findings support a sister relationship between Rhombosoleidae as defined above and Achiropsettidae .

One of the fossils in our analysis, Numidiopleura enigmatica †, is placed with Achiridae , Paralichthodidae and ( Oncopteridae , ( Rhombosoleidae + Achiropsettidae ). When Numidiopleura enigmatica † was first described, it was thought to be a missing link between Psettodes and Pleuronectoidei ( Gaudant & Gaudant, 1969). However, cladistic analysis of this fossil by Chanet (1997) resolved it as Pleuronectoidei incertae sedis. Here, we find that N. enigmatica † represents extinct family diversity within the Soleoidea , with close affinities to Rhombosoleidae and Achiropsettidae . Numidiopleura enigmatica † is the oldest representative of this putative clade. Reconciling the position of N. enigmatica † from a biogeographic standpoint is problematic as the fossil is from the Mediterranean and the distribution of inferred relatives is in the Southern Hemisphere. A cautious interpretation is necessary as the fossil of N. enigmatica † is lost and of uncertain age.

Within Soleoidea , four other families form a monophyletic assemblage— Samaridae , Poecilopsettidae , Soleidae and Cynoglossidae —with well‐supported monophyly (BS = 86%, PP = 0.82, Figures 1 and 2). The monophyly and same branching arrangements of these four families have been documented in three previous studies utilizing independent data sets ( Campbell et al., 2013; Campbell, López, et al., 2014; Harrington et al., 2016). Note that in Figure 2 of Harrington et al. (2016), Aseraggodes xenicus is incorrectly labelled as a cynoglossid, although it is a soleid. Alternative branching arrangements of Samaridae , Poecilopsettidae , Soleidae and Cynoglossidae are presented in a recent mitogenomic study, but the families are monophyletic ( Shi et al., 2018). The fossil Eobuglossus eocenicus † while recently not considered a soleid by ( Near et al., 2012) is demonstrated to be a soleid, in line with previous hypotheses ( Chanet, 1994; Chapleau & Keast, 1988).

Research in flatfish alpha taxonomy is active and room for continued development of the beta taxonomy of the Pleuronectoidei is present. Two notable genera were not examined in this study, Tephrinectes and Thysanopsetta , suggested by Hensley and Ahlstrom (1984) to be removed from Paralichthyidae . Detailed anatomical investigation of Tephrinectes indicates it is a distinct lineage from Paralichthyidae ( Hoshino, 2001; Hoshino & Amaoka, 1998). Further investigations may reveal more family‐level diversity within Pleuronectoidei either through the identification of new distinct lineages or refinement of known genera.