Titanonarke Carvalho, 2010

Marram ̀, Giuseppe, Claeso, Kerin M., Carneval, Giorgio & Kriwe, Jurgen, 2018, Revision of Eocene electric rays (Torpediniformes, Batomorphii) from the Bolca Konservat-Lagerst atte, Italy, reveals the first fossil embryo in situ in marine batoids and provides new insights into the origin of trophic novelties in coral reef fishes, Journal of Systematic Palaeontology 16 (14), pp. 1189-1219 : 1192

Genus † Titanonarke Carvalho, 2010

Diagnosis (emended). Narcinid electric ray unique in having the following two autapomorphic traits: large size (up to about 1 m of TL) and large number of vertebrae (133–155). Additionally, † Titanonarke has the following combination of characters: broadly branched antorbital cartilage, with a third smaller branch posteriorly directed and located at midlength; unfused hypobranchials; iliac process short and straight; prepelvic process wider towards tip than along the shaft; mesopterygium shorter than propterygium and metapterygium; tooth cusp length less than half the length of the blade-like cutting edges; tooth root high and narrow; precaudal tail reaching about 50% of TL; long claspers extending past posterior tips of pelvic fin lobes.

Type species. † Narcine molini Jaekel, 1894 .

Included species. † Titanonarke molini ( Jaekel, 1894) ; † Titanonarke megapterygia sp. nov.

Remarks. Jaekel (1894) was the first to document the presence of electric rays from the Monte Postale site in his comprehensive account of cartilaginous fishes from the Bolca Lagerst¨atte. In this work, he erected the species † Narcine molini based on a nearly complete specimen in part and counterpart housed in the collection of the Museo di Geologia e Paleontologia dell’Universit̀a di Padova ( MGP-PD 26275/6). The specimen previously was assigned to † Narcine gigantea by Molin (1860). However, the holotype of † N. gigantea , housed in the Museum national d’Histoire naturelle, Paris ( MNHN F.Bol567) later was recognized as a thornback and assigned to Platyrhina by Jaekel (1894). Both Eastman (1904, 1905) and Blot (1980) included † Narcine molini in their synoptic lists of chondrichthyans of Bolca. Recently, Carvalho (2010) undertook a re-examination of the holotype of † Narcine molini and two additional specimens recovered from the Monte Postale site in the second half of the twentieth century ( MCSNV IG.135576 and MCSNV IG.91128/9), and erected the genus † Titanonarke containing † N. molini Jaekel, 1894 . The diagnosis of this new genus was based on the presence of some derived characters within narcinids, including the large size, the long precaudal tail reaching about 50% of TL, the absence of dorsal fins, and absence of posteriorly directed branches of the antorbital cartilage. Carvalho (2010) also provided an interpretative phylogenetic analysis in which † Titanonarke was recovered as the basalmost genus within the Narcinidae . Although † Titanonarke clearly exhibits the diagnostic characters of this family, the diagnosis of this Eocene taxon provided by Carvalho (2010) and its relationships to other torpediniforms appear to be controversial. This is primarily due to the apparent absence of some typical narcinoid characters (dorsal fins and third branch of the antorbital cartilage), and to the ambiguous choice of characters used for the phylogenetic inference. Carvalho (2010) also hypothesized the presence of a possible new genus of numbfish in the Monte Postale site based on the observation of two juvenile specimens ( MCSNV IG.135581 and MCSNV IG.VR.91359) indicating characters which were hypothesized to be absent in † T. molini (i.e. third small branch of the antorbital cartilage and a posteriorly directed scapular process). Our detailed revision of the historical and new material derived from recent controlled excavations reveals that the specimens used by Carvalho (2010) were only partially preserved and thus prevented the recognition of those elements whose apparent absence was erroneously regarded as diagnostic of † Titanonarke . Moreover, there are no substantial morphological differences to support the hypothesis that juvenile specimens should be recognized as a new genus because osteological, morphometric and meristic features identify these as belonging to † T. molini (see below). We also recognize the specimen MCSNV IG.135576 (but not MCSNV IG.135581 and MCSNV IG.VR.91359), previously ascribed to † T. molini by Carvalho (2010), as a new species of † Titanonarke . Finally, an integrated comprehensive phylogenetic analysis based on the data derived from the detailed comparative anatomy of the electric rays of Claeson (2014) has revealed new hypotheses about the relationships of Titanonarke within the Torpediniformes .