Makaira colonense, Gracia & Correa-Metrio & Carvalho & Velez-Juarbe & P̆rik & & Kri, 2022

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 : 16-17

† Makaira colonense sp. nov.

( Figs 6C, D, 7D, 12A–C, Supplemental material Fig. S5B)

Diagnosis. An extinct species of Makaira characterized by the following combination of morphological traits (autapomorphic characters indicated by an asterisk): osteosclerotic rostrum and narial cavities enclosed by premaxillaries, prenasals and dermethmoid$; prenasals in dorsal view well separated and the narial cavity is divided into two portions by extensions of the prenasals; large internal canals; from the most proximal end to about 0.5 L distance, the premaxillaries are convex and projected outward along the lateral surface; in lateral view, the premaxillaries occupy about 3 / 4 of the total height at the contact point between prenasals, premaxillary and maxilla.

Derivation of name. The species name ‘ colonense ’ refers to the Colon province of Panama and is used due to the importance of this province for Panamanian palaeontology.

Holotype. MUPAN–STRI39292 , a large nearly complete rostrum.

Occurrence. Late Miocene (6.4–5.8 Ma), Chagres Sandstone Member, Chagres Formation. Bioturbated horizon on Pina beach ( Fig. 1) at 9 ǫ 17 Ɩ 24.89 ʺ N, 80 ǫ 2 Ɩ 25.39 ʺ W, near the town of Pina in the Chagres District, Colon Province, Panama.

Remarks. The rostrum of † Makaira colonense sp. nov. (MUPAN–STRI39292) is nearly complete and consists of complete prenasals and premaxillaries with partially preserved nasals ( Fig. 11 A – C). The estimated length is 672 mm. In dorsal view, the premaxillaries extend over the prenasals ( Fig. 7D) in the proximal part of the rostrum. The narial cavity is divided into two parts separated by extensions of the prenasals (Supplemental material Fig. S5B). In dorsal view, premaxillaries overcomes forming the outline ( Fig. 11 A) instead the prenasals ( Fig. 7C, I–L). In lateral view from the most proximal point to about 0.5 L distance, the premaxillaries are extremely thickened and extended laterally, forming a convex projection ( Fig. 11B). This smooth and rounded projection gives its distinctive shape to the rostrum ( Fig. 7D). The rostrum is osteosclerotic and stout, with an oval outline in cross-section at 0.5 L and 0.25 L distances ( Fig. 7D). The distal tip has a globular outline, is wide and curved slightly upwards in lateral view ( Fig. 11 A – C). In ventral view, the premaxillaries begin to be separate at 367 mm from their distal tips ( VSPM) ( Fig. 11 C). This distance represents approximately 54% of the total length of the rostrum. The nasals are poorly preserved. The internal canals are large and have an oval outline, located in a medial position and are centrally aligned (Table 4; Fig. 6C, D). Both statistical analyses ( Fig. 9) place the rostrum of † M. colonense sp. nov. outside the group formed by all extant species and only can be confused with † M. panamense . However, in † M. colonense sp. nov. the prenasals conversely never contact each dorsally ( Figs 7D, S 5B) and the premaxillaries form the posterior enclosure of the narial cavity (Supplemental material Fig. S5B).