Makaira belgica (Ĺeriche, 1926)

Gracia, Carlos De, Correa-Metrio, Alex, Carvalho, Monica, Velez-Juarbe, Jorge, P ̆ rik, Tom ́ a ̆ s, , Carlos Jarami & Kri, nd Jurgen, 2022, Towards a unifying systematic scheme of fossil and living billfishes (Teleostei, Istiophoridae), Journal of Systematic Palaeontology (2091959) 20 (1), pp. 1-36 : 17-18

† Makaira belgica (Ĺeriche, 1926)

( Figs 7F, 9H, I)

1926 † Brachyrhynchus belgicus Ĺeriche: 443, figs 210, 211.

1978 † Istiophorus belgicus (Ĺeriche) in Fierstine: 8.

1990 † Makaira belgicus (Ĺeriche) in Fierstine: 15, table 2.

Diagnosis. This species is characterized by dorsally positioned internal canals in the rostrum, which represents an autapomorphic trait for this species.

Holotype. IRSNB P1117, holotype is a 200 mm-long distal rostral fragment (Ĺeriche 1926). Middle Miocene , Anvers, Belgium (Ĺeriche 1926; Schultz 1987).

New referred material. MAUL 917/1, is a 500 mm-long, nearly complete rostrum with associated left lower jaw and poorly preserved and deformed skull from the late Miocene of Pietra Leccese Formation, Apulia, Italy ( Carnevale et al. 2002).

Occurrence. Middle Miocene (Burdigalian) to late Miocene (Tortonian).

Remarks. † Makaira belgica represents the earliest record of the genus Makaira . The holotype is represented by a 200 mm distal rostral fragment ( Fig. 8B), which is robust and oval in cross-section ( Fig. 9H, I). At 0.25 L, it has a pair of small and circular internal canals, which are arranged dorsally and parallel along the midline ( Fig. 9H). In the new specimen MAUL 917/ 1 referred to this species, the prenasals and maxillae are well preserved but the nasals are only partially preserved. In the holotype the nasals are only represented by grooves ( Fig. 8B) (Ĺeriche 1926; Schultz 1987). Alveoli and denticles are visible across the completely ventral surface in both specimens ( Fig. 8B) ( Carnevale et al. 2002).

The studied ratios of † M. belgica at the 0.5 L section fall within the rage of recent and fossil M. nigricans , but differ in its dorsally aligned internal canals ( Figs 9H, I, 10) (Ĺeriche 1926; Schultz 1987). This feature represents the only autapomorphy for this species ( Fig. 9H–I). The holotype ( IRSNB P1117) of † M. belgica is represented by a poorly preserved distal rostral fragment and we assign a second specimen, MAUL 917/1, to this taxon, because both specimens have dorsally arranged internal canals ( Fig. 9H, I), representing an autapomorphic trait for this species. Specimen MAUL 917/1 has internal canals in a dorsal position at 0.25 L ( Fig. 9H, I; see also Carnevale et al. 2002), which is consistent with what is seen in the holotype of † M. belgica ( Fig. 9N). Specimen MAUL 917/1 additionally has distinctive ratios for D2/ VSPM and W2/ VSPM. These out-of-range values are interpreted as short VSPM that covers less than 50% of the rostrum length.