1. • Larva vermiform or oblong in shape – 2
• Larva not vermiform and with elaborate flaps, funnel or vestibule – 12
2. • Larva uniformly ciliated – 3
• Larva uniformly ciliated; with two transverse bands of dense cilia – “Trochonemertes” (Micrura sp. “dark” and allies)
3. • Larval eyes present – 4
• Larval eyes absent – 7
4. • Larval eyes intra-epidermal – 5
• Larval eyes sub-epidermal – 10
5. • Single, mid-ventral eye anterior to mouth – 6
• Eyes paired, each eye single or double – Cephalothrix spp.
6. • Lateral cirri present; few anterior cirri – Carinoma spp.
• Lateral cirri present; several anterior cirri are curled – Carinina sp. "chocolate"
7. • Larva with thick, short lateral cirri – Tubulanus spp.
• Larva without lateral cirri – 8
8. • Larva with thick, conspicuous epidermis – Tubulanus sexlineatus
• Larva without distinctively thick epidermis – 9
9. • Larva with prominent apical tuft; < 500 µm in length – modified pilidia
• Pale larva without apical tuft; < 500 µm in length; dorsal furrow – Malacobdella siliqua
• Orange larva with short apical tuft; > 500 µm in length – Tubulanus polymorphus
10. • Larva with two statocysts, each with a polystatolith – Ototyphlonemertes spp.
• Larva without statocysts – 11
11. • Larva orange in color; two pairs of eyes present, the posterior pair closely apposed resembling a single eye – Carcinonemertes errans
• Larva green in color; two pairs of eyes present in advanced individuals (likely one pair in young larvae), neither pair overlapping – Emplectonema sp. 1
• Larval body color not orange or green; two or more pairs of eyes; conspicuous apical tuftpresent or absent – other hoplonemertean larvae (Paranemertes californica, Nipponnemertes bimaculata, Tetrastemma bilineatum, Poseidonemertes collaris, Gurjanovella littoralis, Paranemertes sp. 1, Zygonemertes sp. 1, Pantinonemertes californiensis)
12. • Larval body transparent; shape is sock-like, with large esophageal funnel – Riserius spp.
• Larval body transparent, with prominent epidermal cell outlines and nuclei; shape is helmet-like, with narrow lateral lappets – Hubrechtella spp.
• Larval body transparent; shape is hat-like, with rounded lateral lappets – 13
13. • Juvenile or rudiments with polka-dot pigment spots on amnion – Maculaura spp.
• Amniotic pigment absent; larval lobes and/or lappets with pigment spots or patches – 14
• Amniotic pigment absent; larval lobes and lappets without conspicuous pigmentation – 15
14. • Larval lappets and lobes with pigment spots, lobes scalloped; juvenile with caudal cirrus and two small eyes – Cerebratulus californiensis and allies
• Larval anterior lobe with one pigment patch on either side, lappets not pigmented, lobes not scalloped; juveniles with two eyes and caudal cirrus – Micrura wilsoni
15. • Larva with relatively small episphere (equal to in size, or smaller than lappets) that is shaped like a low dome – Lineus flavescens and allies
• Larva with a relatively large episphere that is shaped like a dome or pyramid – 16
16. • Larval lobes large and floppy; juvenile cirrus absent in advanced larvae; juvenile develops at larval center – Lineus sp. “crescent”
• Larval lobes not floppy or disproportionately large; juvenile cirrus present; juvenile develops at larval center or at oblique angle to larval lobes – 17
17. • Larval episphere as wide as or wider than tall – 18
• Larval episphere taller than wide; juvenile develops slightly off larval center (toward the posterior larval lobe) – Cerebratulus albifrons
18. • Juvenile develops at larval center; caudal cirrus inconspicuous (best visible in newly metamorphosed individuals) and posterior with cluster of lipid granules – Heteronemertea gen. sp. 4
• Juvenile develops at an oblique angle to larval anterior and posterior lobes; caudal cirrus conspicuous – Cerebratulus cf. marginatus and allies