Key:  Order Sacoglossa

Phylum Mollusca
 Class Gastropoda
  Subclass Opisthobranchia

[Sacoglossans are mostly small, greenish herbivores, though some species feed on opisthobranch eggs.  Some have shells, while others have no shells but have ridges, folds, or papilli on the back.  Most have rolled, tube-like rhinophores]

Taken primarily from  Kozloff, 1987, 1996 p. 242 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
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Lower taxonomic level Main Page Alphabetic Index Systematic Index Glossary
1a Cerata present (there may also be a pair of rhinophores); without parapodia (broad lateral outgrowths of the foot) 2
1b Cerata absent; with well developed parapodia that may be turned up to cover the dorsum or spread flat against the substratum Elysia hedgpethi
2a Cerata (about 10) limited to the posterior half of the body; body mostly black (head and tail pale gray) Olea hansineensis
2b Cerata (usually more than 10) on both the anterior and posterior halves of the body; body not black (except in Aplysioipsis smithi) 3
3a Without rhinophores; body slightly flattened; foot broader than the body, tapering abruptly, not extended posteriorly as a tail (head region with pronounced dorsolateral fold; body greenish yellow with black streaks) Alderia modesta
3b With rhinophores; body nearly cylindrical; foot relatively narrow and tapering gradually to form a pointed tail 4
4a Rhinophores solid (body translucent white, with an intricate reddish brown pattern on the cerata as well as on the dorsum) Stiliger fuscovittatus
4b Rhinophores rolled up to form a hollow cylinder, at least for much of their length (the edges may not quite overlap, however) 5
5a Basal portion of rhinophores solid (only the distal part is rolled up); body black with white around the mouth, anterior edge of the foot, tips of the cerata, and within the rhinophores Aplysiopsis smithi
5b Rhinophores rolled up for their entire length; body pale, with a branching green or red pattern on the dorsum and within the cerata (the pattern is formed by branches of the gut and digestive gland) 6
6a With as many as 50 slender cerata (body creamy white, with a green digestive tract) Placida dendritica
6b With only about 18-24 cerata, these plump rather than slender 7
7a Cerata of nearly uniform size and shape, and with a yellow cap at the tip; tail short; digestive tract reddish brown Hermaea oliviae
7b Cerata of varying size and shape, and without a color cap at the tip; tail extending considerably beyond the ceratal area and may even equal it in length; digestive tract golden brown Hermaea vancouverensis

Taxonomic Levels Represented in This Key:

  Elysia hedgpethi
  Placida dendritica
  Stiliger fuscovittatus

Page created by Dave Cowles, 2006
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