Evidence for a close phylogenetic relationship between the teleost orders Tetraodontiformes and Lophiiformes based on an analysis of soft anatomy by Bruno CHANET* (1), Claude GUINTARD (2), Eric BETTI (2), Cyril GALLUT (1), Agnès DETTAÏ (1) & Guillaume LECOINTRE (1) Abstract. – Recent phylogenetic studies based on comparisons of DNA sequences have shown that Lophii- formes (anglerfishes) and Tetraodontiformes (puffers, triggerfishes and sunfishes) were closely related, whereas no morpho-anatomical work has assessed this point. Dissections of 80 fresh specimens belonging to 49 spe- cies of 29 acanthomorph families, coupled with analyses of the literature indicate the existence of shared soft anatomy characters between Lophiiformes and Tetraodontiformes. Among acanthomorphs, anglerfishes, puffers, ocean sunfish and triggerfishes are peculiar in possessing: i) a reduced gill opening; ii) rounded and anteriorly disposed kidneys; iii) a compact thyroid included in a blood sinus; iv) an abbreviated spinal cord; v) an asym- metric liver; and vi) clusters of supramedullary neurons in the rostral part of the spinal cord. The sharing of these unusual characteristics by these two groups might be synapomorphies supporting a close relationship between Lophiiformes and Tetraodontiformes. The present study shows both the importance of comparative anatomy and © SFI the utility of confronting morpho-anatomical and molecular results. Received: 27 Jan. 2013 Accepted: 12 Apr. 2013 Editor: G. Duhamel Résumé. – Des données d’anatomie molle corroborent l’étroite parenté entre Tétraodontiformes et Lophiifor- mes. Des analyses phylogénétiques récentes fondées sur la comparaison de séquences nucléotidiques ont montré Key words que les Lophiiformes (baudroies) et les Tétraodontiformes (poissons-coffres, balistes et poissons-lunes) étaient étroitement apparentés, tandis qu’aucune donnée morpho-anatomique ne l’attestait. La dissection de 80 spé- Lophiiformes cimens frais appartenant à 49 espèces de 29 familles d’acanthomorphes, associée à l’analyse de la littérature Tetraodontiformes montre la présence de caractères partagés touchant l’anatomie des organes mous entre les Lophiiformes et les Phylogeny Tétraodontiformes. Au sein des acanthomorphes, les baudroies, poissons-coffres, balistes et poissons-lunes sont Soft anatomy particuliers en possédant : i) une ouverture branchiale réduite ; ii) des reins arrondis et situés antérieurement dans la cavité abdominale ; iii) une thyroïde compacte incluse dans un sinus veineux ; iv) une moelle épinière courte ; v) un foie asymétrique ; et vi) des groupes de neurones supramédullaires dans la région rostrale de la moelle épi- nière. Le partage de ces caractères singuliers par ces groupes constitue un indice de synapomorphies probables, soutenant l’étroite parenté entre Lophiiformes et Tétraodontiformes. La présente étude montre à la fois l’impor- tance de l’anatomie comparée et l’intérêt d’associer et confronter les résultats des travaux morpho-anatomiques et moléculaires. Until recently, Tetraodontiformes and Lophiiformes were tiform species were viewed as distinctive orders that were regarded as distinct and not closely related orders of acantho- only distantly related to one another within the acantho- morph fishes (Lecointre, 1994; Nelson, 2006). The Lophii- morph teleosteans (Lecointre, 1994; Nelson, 2006). Lophii- formes (anglerfishes such as goosefishes, frogfishes and sea formes and Tetraodontiformes were sometimes listed in close toads) comprise 313 species in 66 genera, in which the first proximity (just before or after) to one another in taxonomic dorsal fin spines are modified as a luring apparatus, while arrangements (Gill, 1893; Jordan and Evermann, 1900; the 101 genera and 357 species that comprise the Tetraodon- Boulenger, 1904; Jordan, 1920, 1923; Berg, 1940), but such tiformes are as diverse as triggerfishes, boxfishes, puffers placements were only poorly, if at all, supported by charac- and ocean sunfishes (Nelson, 2006). Recently, some tetrao- ters and did not correspond to a documented hypothesis of dontiform species have become the subject of many biologi- relationships. Nevertheless, the anatomy of these fishes has cal studies both for their toxicity and their compact genome been rarely compared. Rosen (1973) recognised two clades (Aparicio et al., 2002; Jaillon et al., 2004). On the basis of within the acanthomorphs: the Acanthopterygii, including their respective peculiar anatomy, lophiiform and tetraodon- the Tetraodontiformes, and the Paracanthopterygii, contain- (1) Équipe “Phylogénie”, UMR 7138 CNRS-IRD-MNHN-UPMC, Département systématique et évolution, Muséum national d’Histoire naturelle, CP 26, 57 rue Cuvier 75231 Paris CEDEX 05, France. [[email protected]] [[email protected]] [[email protected]] (2) Laboratoire d’anatomie comparée, ONIRIS - École nationale vétérinaire de l’agroalimentaire et de l’alimentation, Nantes Atlantique, Route de Gachet, BP 40 706, 44307 Nantes CEDEX 03, France. [[email protected]] [[email protected]] * Corresponding author [[email protected]] Cybium 2013, 37(3): 179-198. Evidence for Tetraodontiformes and Lophiiformes relationships CHANET ET AL . ing the Lophiiformes with the Gadiformes, Batrachoidi- formes, Percopsiformes, and Ophidiformes. Even if the sta- tus of these two clades has been questioned and reconsid- ered by several authors (Stiassny, 1986; Stiassny and Moore, 1992; Johnson and Patterson, 1993), Tetraodontiformes and Lophiiformes were still viewed as two distinctive and only distantly related orders (Lauder and Liem, 1983; Johnson and Patterson, 1993; Nelson, 2006), defined on osteological autapomorphies (Tyler, 1980; Pietsch, 1981, 1984, 2009; Pie- tsch and Grobecker, 1987). The absence of some bones, like ribs or nasals (Pietsch, 1981) could be viewed as synapomor- phies of Tetraodontiformes and Lophiiformes, but the occur- rences these absences have to be accurately examined. Miya et al. (2003) analysed the complete sequence of mitochon- drial DNA for 100 higher teleostean species. Their results Figure 1. - Phylogenetic position of Tetraodontiformes and Lophii- showed that Tetraodontiformes and Lophiiformes are two formes (modified from Li (2008); note that in Dettaï and Lecointre monophyletic and closely related groups: anglerfishes appear (2008) tetraodontiforms and lophiiforms are sister-groups). Draw- ings from F. Dejouannet. 1: Angler (Lophius piscatorius, Lophii- as a sister group of a clade comprising two tetraodontiform formes, Lophiidae); 2: Puffer (Tetraodon sp., Tetraodontiformes, species and one caproid, Antigonia capros Lowe, 1843. The Tetraodontidae); 3: Ocean Sunfish (Mola mola, Tetraodontiformes, same relationships for these groups are present in Miya et al. Molidae); 4: Boarfish (Capros aper, Caproidae); 5: Porgy (Sparus sp., Sparidae); 6: Perch (Perca sp., Percidae). (2005), in which the complete sequences of mitochondrial DNA were studied for 102 higher teleostean species. Det- taï and Lecointre (2004) did not find this same close rela- dontiformes and thus did not challenge or corroborate a close tionship between Lophiiformes and Tetraodontidae in their relationship between them. In the other study of Smith and search of notothenioid relatives on the basis of 3525 nuclear Wheeler (2006), the Lophiiformes and Tetraodontiformes and mitochondrial characters. Dettaï and Lecointre (2005) did not appear closely related on the basis of the analysis of analysed the sequences (678 + 527 base pairs) of exons of five gene regions (nuclear and mitochondrial). But this result the MLL (Mixed Lineage Leukaemia-like) gene sequences is quite unique, while 15 different studies (Miya et al., 2003, for ribosomal 28S, rhodopsin gene, mitochondrial 12S and 2005; Dettaï and Lecointre, 2004, 2005, 2008; Yamanoue et 16S in 63 acanthomorph species. In this work, Lophiiformes al., 2007; Mabuchi et al., 2007; Holcroft and Wiley, 2008; and Tetraodontiformes were nested in the same clade, called Li, 2008; Santini et al., 2009; Yagishita et al., 2009; Mat- N by these authors, along with Caproidae, Elassomatidae, schiner et al., 2011; Meynard et al., 2012; Near et al., 2012; Acanthuridae, Siganidae, Pomacanthidae, Drepanidae and Wainwright et al., 2012) conducted by different teams on Chaetodontidae. While studying the sequences of the gene various genes (17 nuclear genes and 36 mitochondrial genes) for the interphotoreceptor retinoid-binding protein (IRBP) in corroborate a close relationship between Lophiiformes and 92 acanthomorph species, Dettaï and Lecointre (2008) found Tetraodontiformes. again this clade. Yamanoue et al. (2007) studied 44 whole Many studies of the skeletal anatomy of these two mitochondrial genomes of acanthomorph species to try to orders have not yet revealed any shared derived characters identify the phylogenetic position of tetraodontiform fishes. that would unite them (Tyler, 1968; Tyler, 1980; Pietsch, This group appeared as monophyletic and placed as a sister- 1981, 2009; Matsuura and Yoneda, 1987; Pietsch and Orr, group of either Lophiiformes plus Caproidae or Caproidae 2007; among many others). The species of each of these alone. Li (2008) analysed the sequences for four nuclear groups are considered as highly derived among euteleostean genes (Rhodopsine, MLL4, IRBP and RNF213) in 200 acan- fishes, with many specializations, skeleton modifications thomorph species; Clade N was redefined and restricted, and autapomorphies, which present difficulties in making and Lophiiformes and Tetraodontiformes