Pitar fulminatus
Similar to Pitar albidus. Pitar fulminatus is less elongate, has more prominent umbones and more inflated valves than P. albidus. The exterior flank of P. fulminata is generally more pigmented than that of P. albidus.
Similar to Pitar helenae. Adults of Pitar fulminatus are typically larger than those of P. helenae. Morphologically, the two species are very similar; however, they have different geographic ranges: P. helenae is found in the Pacific from Baja California to Peru, and P. fulminatus is found in the Atlantic from North Carolina in the United States to Brazil (Palmer 1927, Huber 2010).
Similar to Pitar inflatus. Pitar fulminatus is distinguishable by its thinner-walled, less inflated valves and its less prominent umbones; it also is typically smaller than P. inflatus. In addition, the two species have different geographic regions: P. fulminatus is found in the Atlantic from the United States to Brazil, and P. inflata is found in the Pacific from Indonesia to Japan (Huber 2010).
Similar to Pitar morrhuanas. Pitar fulminatus has a less convex posterior dorsal margin, less prominent umbones and a shinier external surface; its umbones are also less curved anteriorly. P. fulminatus has characteristic dark brown pigmentation at the posterior dorsal margin and on the lunule that are not found in P. morrhuanas.
The overall shape is trigonal ovate. The posterior margin is subtruncated, and the anterior and ventral margins are rounded. The anterior dorsal margin is subconcave and the posterior dorsal margin is subconvex. The valves are equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines and very fine, dense comarginal ribs on the dissoconch. The lunule is rounded, extends 3/4 of the anterior dorsal margin and is defined by a fine shallow groove. The umbo is central and the beaks point slightly to the anterior. The escutcheon is slightly smoother than the area around it, but otherwise not well defined.
The exterior is white and typically has light brown comarginal stripes, radial stripes and/or tent marks. The escutcheon is typically a darker brown, and the lunule may have a blotch of brown coloration near the umbo. The interior is white.
The ligament is external, slightly sunken, extends half the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth (2a, 2b, 4b), none of which are bifid. The posterior tooth (4b) is fused with the nymph, and the anterior (2a) and central (2b) teeth are fused dorsally, forming an inverted "V" shape. There is also one anterior lateral tooth (A2) on the left valve. On the right valve, there are three cardinal teeth: the anterior (3a) and central (1) teeth are not bifid, and the posterior tooth (3b) is bifid. There are also two anterior lateral teeth (A1, A3) on the right valve. The posterior adductor muscle scar is slightly larger and rounder than the anterior adductor muscle scar. The pallial sinus is tapering and extends to the middle of the nymph in length.