MARINE GAMMARIDEAN AMPHIPODA 117 



Acanthonotozomatidae 



Figures 54-56 



Diagnosis. — Mouthparts grouped into cone-shaped bundle pro- 

 jecting from ventral surface of head; accessory flagellum absent or 

 vestigial. See Paramphithoidae, Ochlesidae, Pardaliscidae, La- 

 fystiidae. 



Description. — Accessory flagellum absent, 1- or 2-articulate 

 when present, very small and short; body usually mth dorsal processes; 

 rostrum well-developed; mouthparts rather linear in shape (to fit 

 conical bundle and probably adapted for piercing and sucking) ; 

 mandible especially linear, usually lacking molar or having only small 

 molar protuberance, although triturative molar present in some genera ; 

 palp of mandible always present; lower lip variable, with or without 

 inner lobes, apices of outer lobes occasionally incised; maxilliped with 

 well-developed plates but palp with three or four articles and long 

 or short; coxae 1-4 usually acuminate or subacuminate; gnathopod 

 1 and usually gnathopod 2 very feeble, often minutely chelate, article 

 3 of gnathopod 2 occasionally elongate; rami of uropod 3 longer than 

 peduncle, rami flattened-lanceolate; telson entire or slightly cleft; 

 article 2 of pereopods 3-5 usually with posterior teeth. 



Relationship. — The mandibular molar of Astyridae is larger than 

 but not morphologically distinct from the protuberances occurring 

 in some acanthonotozomatids ; the accessory flagellum of astyrids is 

 1-articulate but long, and the mouthparts are not arranged in a conical 

 bundle. 



The Lafystiidae have a 2-articulate maxillipedal palp, but otherwise 

 the family is so similar to the Acanthonotozomatidae that the two 

 families might be joined together. 



The Stilipedidae resemble Acanthonotozomatidae but apparently 

 the mouthparts are not grouped in a conical bundle; the maxillae 

 are strongly foliaceous but this is true also of Maxilliphimedia. 



With one exception the mouthparts of Pardaliscidae are not grouped 

 in a conical bundle; usually pardaliscids have a multiarticulate 

 accessory flagellum and the inner plates of the maxUlipeds are obsoles- 

 cent. One of the mandibles is especially flattened and heavily toothed. 



The Stegocephalidae lack a mandibular palp. 



Mouthparts of the Paramphithoidae are not arranged in a conical 

 bundle but this distinction is confused by the acanthonotozomatid 

 Bathypanoploea ausiralis (ChUton, 1912) (see Schellenberg, 1931). 

 The mouthparts of B. australis not only are grouped in a quadrate 

 bundle but the molar is absent and the gnathopods are styliform as in 

 most acanthonotozomatids. The type genera of the two families differ 

 in the follo\ving ways: 



