MARINE GAMMARIDEAN AMPHIPODA 515 



Flagellum: proportion to peduncle ( %) or article 5 ( %). 



Number of articles: 0, 1, 2, 3, 4, 5, 6-10, 11-15, 16 + . 

 Ornaments : 



Aesthetascs, calceoli on peduncle and/or flagellum. 



Distinctive spine groups. 



"Fossorial" condition, with long plumose setae. 



MOUTHPARTS 



From lateral view forming a conical bundle below head (rare) or a quadrate bundle 



(common). To be examined before dissection. 

 Amalgamation of mandibles and maxillae into ventral keel (Anamixidae). 



EPISTOMAL-LABRAL COMPLEX (prebuccal) 



Lateral view (primarily of generic importance in Lysianassidae) : 



Epistome and labrum separated by notch (common) or coalesced. 



Epistome formed as lobe dominating labrum, vice versa, or produced together. 

 Shape of lobes: 



Epistome: flat, rounded, acute. 



Labrum: flat, rounded, acute. 

 Prebuccal mass inconspicuous and of normal gammaridean proportions. 



UPPER LIP (anterior view) 



Ventral margin: rounded, truncate, incised, lobed asymmetrically or symmetri- 

 cally. 



MANDIBLE 



Shape and size of body: bulky (Synopiidae), styliform (Acanthonotozomatidae) , 



ely triform (Stegocephalidae, Fardaliscidae), OR normal (Gammaridae). 

 Incisor: normal, extremely broadened; needle-like, toothed, untoothed, teeth 

 separated by flat margin. 

 Lacinia mobilis, if present on either right or left mandible: toothed, special 

 shape such as vermiform. 

 Spines proximal to lacinia mobilis: 1-2; 3-6; 7 + - 

 Molar: Absent. 



Size: small (fig. 1260, medium (fig. r26e), large (fig. 12Gg), fully dominating 



mandible (fig. 166d). 

 Shape: cylindrical, cuboidal, laminate, conical, tuberous. 

 ■ Texture: triturative (rasp-like), spinose (spines articulate), setulose, minutely 

 fuzzy, striate, smooth. 

 Accessory seta or spine on triturative molar. 

 Palp: 



Number of articles: 0, 1, 2, 3. 



Attachment position relative to molar: over (level with), distal to, proximal 



to (variation from "level" primarily in Lysianassidae). 

 Relative length of articles : 1 = ( %) ; 2 = 1 00 % ; 3 = ( %) . 

 Shape: 



Article 3: cylindrical, falconiform, tuberculiform. 

 Article 2: occasionally curved strongly. 

 Article 1: rarely with distal cusp. 

 Setation: article 3: distal only, medial. 

 Disymmetry of right and left members (especially lacinia mobilis, incisor, spine- 

 row). 



