Sagittunio subrostata shell description:

“Shell elongated, irregularly elliptical, subsolid, somewhat inflated, with moderately full beaks sculptured with numerous delicate ridges that are sharply drawn up in the middle; very slightly winged; rounded in front and rather sharply pointed behind; growth lines irregular; posterior ridge moderately developed; surface dull, dirty greenish-yellow, generally having faint, wide wavy rays on the hinder portion, often having concentric bands of lighter and darker color; teeth compressed, two pseudocardinals in each valve, the upper in the right smaller, one lamellar lateral in the right valve and two in the left; muscle scars shallow; beak cavities moderate; nacre bluish-white, scarcely thicker in front.  The dorsal and ventral lines of the male shell are nearly parallel; it is more or less angled at the post-base and ends behind in a rather sharp point above the middle; the female shell is narrowed in front, with a very large, rounded marsupial swelling and in front of this the basal line is incurved” (Simpson, 2014; Mather, 2007).