Lycopteridae, Liu, Su, Huang & Chang, 1963

Hilton, Eric J. & Lavoué, Sébastien, 2018, A review of the systematic biology of fossil and living bony-tongue fishes, Osteoglossomorpha (Actinopterygii: Teleostei), Neotropical Ichthyology 16 (3), pp. 1-35 : 2-3

† Lycopteridae and other Stem-Group Osteoglossomorpha.

† Ichthyodectiformes , a group of predatory Jurassic and Cretaceous fishes ( Cavin et al., 2013), had been closely associated with Osteoglossomorpha (e.g., potentially within Osteoglossomorpha by Greenwood et al., 1966; Taverne, 1979), due in part to general body form and superficial similarity. It was shown by Patterson, Rosen (1977), however, that † Ichthyodectiformes was best interpreted as a stem--group Teleostei, phylogenetically separate from Osteoglossomorpha, and this has been supported in recent analyses of relationships among basal teleostean fishes (e.g., Arratia 1997, 1999, 2008).

Members of † Lycopteridae ( Fig. 1 ) are a group of generalized, plesiomorphic osteoglossomorph fishes. According to Nelson et al. (2016), three genera are included in the family († Lycoptera, † Jiuquanichthys, and † Kuyangichthys), although Zhang (2006) found the relationships of all of these basal genera to be largely unresolved along the stem of Osteoglossomorpha. The recently described monotypic genus † Kokuraichthys from the Early Cretaceous of Japan was interpreted to be either a member of † Lycopteriformes (co-extensive with † Lycopteridae ) or Hiodontiformes ( Yabumoto, 2013). A number of possible stem-group osteoglossomorphs have been identified, but not assigned to a specific family (including some taxa included within † Lycopteridae ). Without exception, these fishes come from Early Cretaceous deposits in Asia, primarily China. Included among these taxa are † Jinanichthys , † Tongxinichthys ( Fig. 2a ; see Zhang, Jin, 1999), and † Xixiaichthys .

The group † Huashia + † Kuntulunia ( Fig. 2b ) has been interpreted as both a stem-group (e.g., unresolved node with Hiodontiformes and all other osteoglossomorphs; Zhang, 2006), sister to Notopteroidei + Osteoglossidae ( Zhang, 1998) , or as more closely related to Arapaiminae (e.g., based in part on preopercular and opercular shape; Li, Wilson, 1999). Similarly, † Paralycoptera , from the Early Cretaceous (or possibly Late Jurassic as well; Tse et al., 2015) of China, was initially described as a member of † Lycopteriformes ( Chang, Chou, 1977); † Tanolepis ( Fig. 2c ; Jin, 1991) is either a synonym ( Jin et al., 1995; Xu, Chang, 2009) or sister-group ( Li, Wilson, 1999) of † Paralycoptera . Ma, Sun (1988) and Jin et al. (1995) suggested that it possessed reticulate scales, indicating an affinity to Osteoglossidae (although concluding that† Paralycoptera was within crown Osteoglossidae , Zhang, 2006 noted differences in the details of the pattern of reticulation between the two groups). However, Xu, Chang (2009: figs. 8c,d) studied and illustrated very well preserved specimens that preserved the details of the scales, and show that these do not bear any furrows, but rather are large cycloid scales with fine circuli and a few radii (and are similar in overall form to the scales of Pantodon ; Hilton, 2003: fig. 39d). Li, Wilson (1999) recovered it as sister to Osteoglossoidei (sharing similarities in the position and angle of the jaw and six hypurals), Zhang (2006) found it to be within crown-group Osteoglossidae (sister to Osteoglossinae + †Phareodontinae; supported only by homoplasies), and Xu, Chang (2009), who found this genus to be intercalated between Mormyroidea and all fossil and living Osteoglossidae (sharing with the latter the condition of having the entire post- and suborbital region of the palatoquadrate covered by the infraorbitals). Wilson, Murray (2008; also Murray et al., 2010, 2018), in contrast, recovered † Paralycoptera + † Tanolepis as a stem group osteoglossomorph, just above the level of † Lycoptera. For details on the history of phylogenetic hypotheses for these and other stem-group osteoglossomorphs, including synapomorphies supporting the various hypotheses, the reader is referred to Shen (1996), Li, Wilson (1999), Zhang (2006), and Xu, Chang (2009). A full taxonomic and phylogenetic review, however, of many of these fishes, including those that were historically included in † Lycopteridae , is needed.

Figures

Fig. 1. †Lycopteridae. Lycoptera davidi, Early Cretaceous, China (UMA F10652; 110 mm SL). Scale bar = 2 cm.

Fig. 2. Stem-group Osteoglossomorpha. Reconstructions of a. †Tongxinichthys microdus (modified from Zhang, Jin, 1999: fig. 2), b. †Kuntulunia longipterus (modified from Zhang, 1998: fig. 11), and c. †Tanolepis ningjiagouensis (modified from Jin, 1991: fig. 1; note that †Tanolepis has been suggested to be a synonym of †Paralycoptera).