New Insights on the Osteology and Taxonomy of the Osteoglossid Fishes Phareodus, Brychaetus and Musperia (Teleostei, Osteoglossomorpha)
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BULLETIN DE L’INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE SCIENCES DE LA TERRE, 79: 175-190, 2009 BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN AARDWETENSCHAPPEN, 79: 175-190, 2009 New insights on the osteology and taxonomy of the osteoglossid fishes Phareodus, Brychaetus and Musperia (Teleostei, Osteoglossomorpha) by Louis TAVERNE TAVERNE, L., 2009 – New insights on the osteology and taxonomy muelleri offre une morphologie évoluée du museau. Les deux of the osteoglossid fishes Phareodus, Brychaetus and Musperia nasaux, articulés avec les frontaux, sont jointifs sur presque (Teleostei, Osteoglossomorpha). Bulletin de l’Institut royal des toute leur longueur, sauf à leur extrémité antérieure où un petit Sciences naturelles de Belgique, Sciences de la Terre, 79: 175-190, dermethmoïde, largement séparé des frontaux, s’intercale entre eux, 13 figs, Brussels, October 31, 2009 – ISSN 0374-6291. comme chez Osteoglossum et Scleropages. Brychaetus est donc un genre valide et non pas un synonyme de Phareodus. L’auteur montre aussi que l’ostéoglossidé Musperia radiata, de l’Éocène d’Indonésie, présente la même morphologie évoluée du museau Abstract que Brychaetus et les Osteoglossidae récents. Le squelette caudal de Musperia est décrit pour la première fois. Les vertèbres préurale The author describes the snout osteology of the fossil Osteoglossidae 1 et urale 1 portent des neurépines complètes. Les cinq hypuraux Phareodus and Brychaetus. He shows that the two genera sont autogènes. Il y a une paire d’uroneuraux et pas d’épural. considerably differ in their naso-ethmoid region. Indeed, Phareodus encaustus and P. queenslandicus possess a large dermethmoid Mots-clefs: Teleostei, Osteoglossidae, Phareodus, Brychaetus, contacting the frontals and separating the two nasals from each Musperia, ostéologie. other, which is the primitive condition within teleosts. P. testis is a little more specialized. Its dermethmoid still separates partially the two nasals but it begins to lose its contact with the frontals. On the contrary, Brychaetus muelleri exhibits a specialized snout Introduction pattern. The two nasals, articulated with the frontals, are joined together on almost their entire length, except at their anterior edge Osteoglossomorpha are a super-order of primitive where a small dermethmoid, largely separated from the frontals, is teleosts existing since the Jurassic-Cretaceous boundary inserted between them, as in Osteoglossum and Scleropages. Thus, Brychaetus is a valid genus and not a synonym of Phareodus. The (CHANG & MIAO, 2004: 547). They comprise three author also shows that the osteoglossid Musperia radiata, from the orders: the Hiodontiformes, the Osteoglossiformes Eocene of Indonesia, displays the same advanced snout pattern as and the Mormyriformes (= Notopteriformes). Some Brychaetus and the two Recent Osteoglossidae. The caudal skeleton authors bring down the last two orders to a subordinal of Musperia is described for the first time. The first preural and the rank, the Osteoglossoidei and the Mormyroidei, and first ural centra bear complete neural spines. The five hypurals are autogenous. There is a pair of uroneurals and no epural. gather them in a larger order of Osteoglossiformes sensu lato. Others separate the Lycopteridae from the Keywords: Teleostei, fossil Osteoglossidae, Phareodus, Hiodontiformes and erect for them a peculiar order: Brychaetus, Musperia, osteology. the Lycopteriformes. Some osteoglossomorph fossil genera and families are left incertae ordinis. The recent Résumé Osteoglossomorpha inhabit fresh-water environments but the fossil species comprise both marine and fresh- L’auteur décrit l’ostéologie du museau des Osteoglossidae fossiles water members. Phareodus et Brychaetus. Il montre que les deux genres diffèrent Osteoglossiformes or bonytongues are still considérablement au niveau de la région naso-ethmoïdienne. En represented today by five tropical genera:Osteoglossum effet, Phareodus encaustus et P. queenslandicus possèdent un grand dermethmoïde en contact avec les frontaux et qui sépare les CUVIER, 1829 and Arapaima MÜLLER, 1843, both from deux nasaux l’un de l’autre, ce qui est la situation primitive chez les South America, Heterotis CUVIER & VALENCIENNES, téléostéens. P. testis est un peu plus spécialisé. Son dermethmoïde 1846 and Pantodon PEETERS, 1876, both from Africa, continue à séparer partiellement les deux nasaux mais il commence and Scleropages GÜNTHER, 1864 from northern à perdre son contact avec les frontaux. A l’inverse, Brychaetus 176 Louis TAVERNE Australia and south-eastern Asia. These five Recent more recently, Phareodus songziensis ZHANG, 2003 genera are included in three families, the Osteoglossidae from the Eocene of the Hubei Province, China (COPE, for Osteoglossum and Scleropages, the Arapaimidae 1873: 638, 1878: 77; HILLS, 1934: 160; THORPE, 1938: (= Heterotidae) for Arapaima and Heterotis, and the 289; ZHANG, 2003: 328). Pantodontidae for Pantodon (TAVERNE, 1979, 1998). HILLS (1934: 160-164), working only on P. Some authors recognize only a subfamilial rank to queenslandicus, was the first to give useful osteological these families, the Osteoglossinae, the Arapaiminae (= information on Phareodus. Later, ROELLIG (1967: 19- Heterotinae) and the Pantodontinae, and group all three 49), in his unpublished Ph. D. thesis, TAVERNE (1978: in a family Osteoglossidae sensu lato (see for instance 7-32), LI (1994) and LI et al. (1997) have studied NELSON, 2006: 104-106). thoroughly the osteology of the two North-American The purpose of this paper concerns three fossil genera and of the Australian species of Phareodus. of Osteoglossidae. I wish to discuss some problems WOODWARD (1901: 74) was apparently the first to regarding Phareodus LEIDY, 1873 (= Dapedoglossus put Dapedoglossus and Phareodus into synonymy, COPE, 1877) and Brychaetus WOODWARD, 1901, on giving the priority to the former because LEIDY the one hand, and to complete the study of the genus (1873) had left Phareodus undefined. THORPE (1938: Musperia SANDERS, 1934, on the other hand. 289) agreed with this synonymy but, in opposition to WOODWARD (1901), invalidated Dapedoglossus because of the priority of Phareodus. This use of Material and methods Phareodus instead of Dapedoglossus is now currently accepted by all the specialists working on fossil and The specimens used for the present study are listed Recent Osteoglossomorpha. in appendix 1. The material was observed with a In his study of the ichthyofauna of the Green River stereomicroscope WILD M5 and the drawings made by the Formation, GRANDE (1984: 70) stated that there were author with a camera lucida. only two valid species of Phareodus in those North- American strata: P. encaustus (= P. acutus, P. sericeus, The problem of the snout region of Phareodus (Figs P. aequipinnis and P. brevicaudatus [pro parte]), the 1-8) type-species, and P. testis (= P. brevicaudatus [pro parte]). That was already the opinion expressed by The first fossil Osteoglossidae ever discovered in TAVERNE (1978: 7). This view was followed by later North America was collected from the fresh-water authors (LI, 1994; LI & WILSON, 1996; LI et al., 1997; Eocene Green River Formation of Wyoming. It ZHANG, 2006; WILSON & MURRAY, 2008; among many consisted only of a body fragment with some big others). reticulated scales (COPE, 1884: pl. 6, fig. 1) and was Phareodus is a rather big, fusiform and deep-bodied named Osteoglossum encaustum by COPE (1871: teleost (Figs 1-2). Some large specimens exceed 50 cm 430). A little later, LEIDY (1873: 99) described from of total length. As in some other fossil Osteoglossidae, the same deposits five mandibular fragments. He the frontal is wide, with a lateral margin presenting a recognized them as different from Osteoglossum and marked expansion above the orbit, and the jaws bear thus erected a new genus and a new species: Phareodus strong, long and acuminate teeth. Phareodus certainly acutus LEIDY, 1873. Four years later, COPE (1877: 807) was a fast-swimming fish and one of the principal described some new osteoglossid specimens from the predators present in its lacustrine environment. When Green River Formation and created also a new genus seen in side view, P. encaustus can be distinguished and a new species: Dapedoglossus testis COPE, 1877, easily from P. testis. Both fishes possess large posterior which he figured later on (COPE, 1884: pl. 7, fig. 1). infraorbitals, as all Osteoglossidae, but the former He included his former O. encaustum in the same offers the third infraorbital longer than deep and the new genus as Dapedoglossus encaustus (COPE, 1877: fourth one as deep as long (ROELLIG, 1967: fig. 6; 808). Other species were described during the same TAVERNE, 1978: fig. 8; GRANDE, 1984: fig. II.33a; period and also during the following years: Phareodon LI, 1994: figs 5B, 8, LI et al., 1997: fig. 3), while the [a misspelling for Phareodus] sericeus COPE, 1873, latter exhibits the third and fourth infraorbitals deeper Dapedoglossus aequipinnis COPE, 1878 and Phareodus than long (ROELLIG, 1967: fig. 8; AVERNET , 1978: fig. brevicaudatus THORPE, 1938, all three from the Green 2; GRANDE, 1984: fig. II.33b; IL , 1994: fig. 5C; IL et River Formation, Phareodus queenslandicus HILLS, al., 1997: fig. 8). There are other minor differences 1934 from the Eocene of Queensland, Australia, and, between the two North-American species (ROELLIG, Osteologic and taxonomic review of Phareodus, Brychaetus and Musperia 177 Fig. 1 – Phareodus encaustus