Lepidogalaxias
Creators: name: Williams, R. R. G.
Publisher: name: Zenodo
Year: 1997
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Osmeriformes
Lepidogalaxiidae
Lepidogalaxias

description: Lepidogalaxias+Galaxiidae + Aplochitonidae(8B) Lateral foramen for hyomandibular branch
of facial nerve at ventral end of lateral strut ofhyomandibular (see synapomorphy 8 for details). A lateral strut is absent inLovettia.
(13) Mesopterygoidal teeth reduced in number or absent (Fig. 13: BA). These teeth are also absent in esocoids, salmonids, salangids, alepocephalids, and the Argentinoidea, and are few in platytroctids. Primitively in galaxioids (Retropinnidae + Prototroctidae) and osmerids the entire medioventral surface of the mesopterygoid bears numerous teeth (Williams, 1987).
(14) Metapterygoid small with axe-shaped endochondral part (shared with Novumbra, Dallia, and some Argentinoidea). It is smaller in the latter three taxa, and in Novumbra and Dallia overlaps a unique anteroventral wing of the hyomandibular. Primitively, the metapterygoid is somewhat large with a prominent rectangular or lunate endochondral section. 10hnson & Patterson (1996) believe that a greatly reduced metapterygoid that fails to contact the symplectic and hyomandibular unites only Lovettia and Lepidogalaxias. However, the metapterygoid is also relatively small in Aplochiton and the Galaxiidae. Although the metapterygoid does not contact the hyomandibular and symplectic in Lovettia and Lepidogalaxias, this is also true of the equally small
galaxiids Galaxias paucispondylus (Williarns, 1987), Galaxiella pusilla and G. nigrostriata (Frankenberg, 1969). Furthermore, the metapterygoid does not contact the symplectic and just barely contacts the hyomandibular in Aplochiton taeniatus (Fig. 6), and contacts neither the symplectic nor the hyomandibular in A. zebra (McDowall, 1969, fig. 3).
(15) Adductor mandibulae with unique maxillomandibular ligament. Osmerids (Fig. 14) and more generalised and primitive clupeomorphs and elopomorphs have the primitive state. The ostariophysan pattern is an autapomorphy (Fink & Fink, 1981; Howes, 1985). Primitively, there is one external division of the adductor mandibulae, section A2. There is also an Aw section (= intramandibularis) anterior to A2 that inserts in and fills the Meckelian fossa on the medial surface of the lower jaw. Section A2 inserts mainly on the medial surface of the lower jaw (via a tendinous aponeurosis) and connects with the maxilla and the posterolateral surface of the lower jaw via the maxillo-mandibular ligament (= ligamentum primordium, labelled L.x, L.y, and L.z on Fig. 14). In Lepidogalaxias, Galaxiidae and
Aplochitonidae the maxillo-mandibular ligament extendsfrom the anterolateral end of section A2 to the maxilla. However, the part of the maxillo-mandibular ligament attaching onto the lower jaw is unlike the outgroups. The section extending to the angulo-articular (Figs 9- 12: L.y) is reduced so there is almost no separate segment (Fig. 14: L.z) extending from the adductor mandibulae to the main part (L.x-L.y) of the maxillomandibular ligament. The maxillo-mandibular ligament also has a new section (Figs 9-12: L.w) extending anteroventrally from the intersection of L.x and L.y to the coronoid process (dentary).
(16) Tendinous aponeurosis on which medial fibres of section A2 ofadductor mandibulae insert not connected
with posteriormost end of maxilla-mandibular ligament or barely connected with it (shared with the argentinoid Bathylagus). The state in Lovettia could not be determined mainly because of small specimen size. Primitively, there is a distinct connection between the anterodorsal edge of the tendinous aponeurosis (before it bifurcates anteriorly) and the posteriormost end of the maxillo-mandibular ligament.
(17) Short ligament between posteromedial surface of maxilla and coronoid process of lower jaw (Fig. 9: L). Although the posteromedial surface of the maxilla is connected to the coronoid process via connective tissue in the other salmoniforms, none has a similar ligament. All esocoids have a ligament between the coronoid process and maxilla (Figs 15, 16, 18, 19: L.cm), but it is not the maxillo-mandibular ligament since both occur in Esox (Fig. 18). It is not homologous with the galaxioid ligament because it is much longer and flatter, extends anteroposteriorly, and inserts farther anteriorly on the maxilla. Also, connective tissue extends between the posteromedial surface of the maxilla and the coronoid process, but there is no ligament. This coronoid-maxilla ligament IS a new esocoid synapomorphy (Williams, 1987).
(18) Adductor arcus palatini expanded anteriorly so insertion includes dorsal surface of mesopterygoid (shared with Esocoidei, Salmoninae, and Argentinoidea). Primitively, it is posterior and inserts on the hyomandibular, and usually the metapterygoid (see also Winterbottom, 1974).
description: Published as part of Williams, R. R. G., 1997, Bones and muscles of the suspensorium in the galaxioids and Lepidogalaxias salamandroides (Teleostei: Osmeriformes) and their phylogenetic significance, pp. 139-166 in Records of the Australian Museum 49 (2) on pages 155-157, DOI: 10.3853/j.0067-1975.49.1997.1263, http://zenodo.org/record/4655107