Spathochoira calvertense ( Berry, 1917 ) 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 : 13

† Spathochoira calvertense ( Berry, 1917) comb. nov.

( Figs 7B, 8A, 9J, K)

1917 † Istiophorus calvertensis Berry : 461, figs 1, 2.

1987 † Pseudohistiophorus calvertensis (Berry) , Schultz: 120, tab. 2.

1990 † Makaira calvertensis (Berry) ; Fierstine: 15, tab. 2.

Diagnosis. This taxon is characterized by the following combination of morphological traits (an asterisk indicates autapomorphic traits): a sub-cylindrical and anteriorly gradually tapering rostrum with extremely large internal canals and that are oval in cross-section in the most distal part; in having a concave ventral margin in the anterior two-thirds forming a pronounced ventral canal along the whole length of rostrum resulting in a cross-sectional shape reminiscent of a pig nose at 0.5 L $; prenasals that terminate close to distal tip$.

Holotype. USNM 9344, a 310 mm long distal rostral fragment.

Occurrence. Late Miocene, Eastover Formation, Tar Bay, James River, Virginia, USA (see also Fierstine 1998, 2001, 2006).

Remarks. † Spathochoira calvertensis gen. nov. is a 310 mm long distal fragment of a rostrum that is dorsally covered by poorly preserved denticles at 57.3 mm from its distal tip ( Fierstine 1998, 2001). The rostrum is sub-cylindrical in cross-section, tapering gradually until the cross-section becomes oval in outline towards the most distal part ( Berry 1917) ( Fig. 8A). The distal tip is slender and resembles that of Istiompax indica ( Fig. 7I). There are two grooves on the dorsal surface that represent the sutures for prenasals ( Fig. 8A). These grooves decrease gradually distally until they disappear completely near the distal tip (P distance) ( Berry 1917). The ventral surface of the rostrum is concave in its anterior two thirds and there is a pronounced median suture that forms a distinct canal identifiable along the whole length of the rostrum ( Berry 1917) ( Figs 8A, 9J, K). The rostrum is broken proximally and the transversal fracture represents the 0.5 L distance ( Fig. 9J) ( Fierstine 2001). A pair of large internal canals is visible ( Table 3 ), which are located at 11.0 mm from the dorsal surface of the rostrum (DD1 distance) ( Fig. 9J). The internal canals are very large based on their proportion relative to the rostral depth (D1) (Table 4). The position of the canals ( Fig. 9J, K) is medial and they have a central arrangement following our terminology (Supplemental material Fig. S2). The canals are levogyres (Supplemental material Fig. S2I) rotated about 40 ǫ, they are wider inferiorly and separated from each other by 1.0 mm ( Berry 1917). In the midline suture, c. 7.0 mm dorsomedial to the canals, a central oblanceolate foramen with a 1.0 mm diameter is present ( Fig. 9J) ( Berry 1917; Fierstine 2001). The cross-section at 0.25 L for this specimen was studied with the help of CT scans and estimated to be 134 mm from the distal tip ( Fierstine 1998, 2001) ( Fig. 9K). The CT results show that the rostrum is oval, the ventral convexity is visible, and the internal canals are ovals and proportionately large ( Fig. 9J, K). The internal canals at this position are in a medial position, centrally arranged and are 5.72 mm height (H2), 3.29 mm wide (N2) and are separated by 2.0 mm bone ( Fierstine 1998, 2001) ( Fig. 9K, Supplemental material 1).