Key to Suborder Aeolidacea

Phylum Mollusca
 Class Gastropoda
  Subclass Opisthobranchia
   Order Nudibranchia

Taken primarily from  Kozloff, 1987, 1996  p. 255 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
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1a Each ceras with a sail-like ridge on its posterior side (the ridge begins near the base and runs for much of the length of the ceras) (length up to 2 cm) Fiona pinnata
1b Cerata without a sail-like ridge on the posterior side 2
2a At least a few rows of cerata located anterior to the bases of the rhinophores 3
2b None of the rows of cerata located anterior to the bases of the rhinophores (some may be at the same level as the rhinophores, however) 7
3a Longest cerata more than half the length of the body; cerata usually oriented approximately at right angles to the anterior-posterior axis of the body; foot proportionately broad (usually less than 3 times as long as wide), tapering to a point at the tail Cumanotus beaumonti
3b Longest cerata less than one-third the length of the body; cerata usually oriented approximately parallel to the anterior-posterior axis of the body; foot relatively narrow (usually more than 4 times as long as wide), bluntly rounded at the tail 4
4a Anterolateral corners of foot projecting as acute pedal tentacles (photo); body covered with gray to brown spots, these being most dense on the cerata (some specimens, especially from floats, lack pigment); usually with a prominent triangular white patch just anterior to the rhinophores; hepatic diverticula not clearly visible within the cerata of pigmented specimens; usually associated with anemones, especially Metridium and Anthopleura; length often attaining 5 cm Aeolidia papillosa
4b
5a
5b
6a
6b
7a Anterolateral corners of foot elongated, forming rather prominent tentacles 8
7b Anterolateral corners of foot broadly rounded or somewhat triangular, but not forming prominent tentacles 13
8a Basic body color purple; rhinophores and cerata bright orange for their entire length Flabellina iodinea
8b Basic body color not purple, usually translucent white or grayish; rhinophores and cerata not orange for their entire length (they may, however, be partly orange) 9
9a With an orange band beginning just anterior to the rhinophores and passing between them, reaching the first group of cerata (a similar orange band may be present on the cardiac region); orange areas usually bordered by broad, opaque white or luminous blue dorsomedial lines that begin on the oral tentacles and continue to the tip of the tail; tips of cerata usually orange or chrome yellow, but with some white at the extremity
Hermissenda crassicornis
9b Without orange bands on the dorsum; white lines on the dorsum, if present, narrow and often interrupted; tips of cerata may be opaque white, but rarely orange 10
10a
10b
11a
11b
12a
12b
13a
13b
14a
14b
15a
15b
16a
16b
17a
17b
18a
18b
19a
19b
20a
20b



Taxonomic Levels Represented in this Key:

  Aeolidia papillosa
  Hermissenda crassicornis



Page created by Robbie Wheeling, 7-2002
Edited by Hans Helmstetler 1-2003, Dave Cowles 2005, 2008