FISHERY BULLETIN: VOL. 83, NO. 3 



CRANGONIDAE 



(Genera Argis, Crangon, Mesocrangon, 

 Paracrangon, Sabinea, and Sclero crangon) 



Rostrum nearly always present and long (at least 

 1/4 length of carapace), spiniform, and always with- 

 out teeth (rostrum spinulose in Stage I larvae of 

 Paracrangon echinata); supraorbital spine absent; in- 

 ner flagellum of antennule a setose spine or oblong 

 projection rather than a plumose seta; tip of antennal 

 scale never segmented; exopodite usually only on 

 pereopod 1 (rarely on pereopod 2); maxillule without 

 subterminal seta on basipodite; dorsal spine may be 

 on abdominal somite 3 or keels on both abdominal 

 somites 2 and 3; usually posterolateral spines on 

 abdominal somite 5; endopodite of pleopods undevel- 

 oped; usually telson widens posteriorly, never with 

 more than 1 pair of lateral spines. Pereopods 1 sub- 

 chelate at about Stage V. Anal spine absent until 

 about Stage IV. 



The principal morphological characters and 

 number of larval stages of known larvae of 

 crangonid shrimp of the northern North Pacific 

 Ocean are summarized in Table 6. 



Genus Argis Kr^yer 



In Stage I, rostrum styliform; pereopods and pleo- 

 pods developed but not functional; exopodite on 

 pereopod 1 rudimentary or absent; abdominal somite 

 3 without dorsal spine; abdominal somite 5 with 

 posterolateral spine (posterolateral spine absent in 

 megalopa of A. dentata). 



Argis crassa'' (Rathbun) 



Only Stage I described, known parentage; figure 2 



in Ivanov (1968). 

 Not Stage I A. crassa as described by Makarov 



(1967) in figure 21. 



Antennal scale without distal spine on outer 

 margin; endopodite of maxillule with 5 setae; sca- 

 phognathite of maxilla with 9 setae; abdominal 

 somites 2-5 fringed dorsally with small spinules; 

 telson and abdominal somite 6 jointed; telson with 8 

 + 8 setae. Length: 7.5 mm. Range: Sea of Japan 

 to Bering Sea to San Juan Islands, WA; depth, 4-125 

 m (Butler 1980). 



Argis dentata (Rathbun) 



Three larval stages. Stage I described, known 

 parentage from Pacific Ocean; Stage I-III de- 

 scribed, from plankton from Atlantic Ocean. 



Stages I-III, from plankton; figures 1-6 in Squires 

 (1965). 



Stage I, known parentage; figure 3 in Ivanov 

 (1968). 



Megalopa, from plankton; described as "Necto- 



'Makarov (1967) described a crangonid larva from plankton that 

 has a short rostrum flattened dorsoventrally. He assumed it was 

 Argis (= Nectocrangon) crassa. According to Ivanov (1968), who 

 reared Stage I A. crassa from known parentage, the larva described 

 by Makarov is neither Argis crassa nor a later stage of Argis 

 crassa. The short flattened rostrum, however, is typically a post- 

 larval (juvenile) characteristic of crangonid shrimp. The specimen 

 described by Makarov, therefore, is probably a juvenile rather than 

 a larva. 



Table 6. — Principal morphological characteristics and number of larval stages of known larvae of crangonid shrimp 

 of the northern North Pacific Ocean, -i- = yes; - = no; ? = unknown. 



'Estimated. 

 'Undeveloped pereopods. 



280 



