1a | Eggcase large >90Â mm ECL, with well-developed aprons | 2 |
1b | Eggcase small-medium in length 40Â <Â ECLÂ <Â 70Â mm, with moderate or narrow aprons | 3 |
2a | Eggcase rectangular: ECL approximately two times the ECW (ECL range = 153–177 mm; ECW range = 61.8–80.5 mm) with well-developed aprons (AAL range = 38.2–49.7 mm; PAL range = 26.2–40.9 mm) | D. nidarosiensis |
2b | Eggcase rectangular: ECL approximately two times the width (ECL range = 91.6–116.2 mm; ECW range = 48.9–67.5 mm). Developed aprons (AAL range = 20.3–31.7 mm PAL; range = 7.7–20.8 mm). Short anterior and posterior horns | D. oxyrinchus |
2c | Eggcase rectangular: ECL approximately two times the ECW (ECL range = 113–133 mm; ECW range = 64.7–72.2 mm). Developed aprons (AAL range = 18.5–25.7 mm; PAL range = 17.5–26.6 mm). Long and thin horns, particularly the anterior (about 50% of ECL) | R. brachyura |
3a | Eggcase small-medium in length 40Â <Â ECLÂ <Â 70Â mm with evident or narrow keels | 4 |
3b | Eggcase small and rectangular (ECL range = 41.8–56.5 mm) without keels | 5 |
4a | Eggcase moderate in size (ECL range = 62.5–67.5 mm), rectangular/almost square in shape (ECL approximately 1.4 times the ECW). Aprons and keels developed. Anterior horns moderate and thin, posterior horns short and sturdy | R. clavata |
4b | Eggcase small (ECL range = 39.7–55.4 mm) rectangular/almost square in shape (ECL approximately 1.4 times the ECW). Evident keels and both anterior and posterior horns moderate and thin | R. asterias |
4c | Eggcase moderate in size (ECL range = 56.6–69.2 mm) with rectangular shape (ECL approximately two times the ECW). Narrow keels. Anterior horns moderate and thin, posterior horns moderate and sturdy | R. polystigma |
5a | Anterior and posterior horns short | R. miraletus |
5b | Moderate posterior horns and very long, thin and curved inwards | L. melitensis |