WALTERS: ECOLOGY OF HAWAIIAN SERGESTID SHRIMPS 



same depth as adults of the small species. The 

 clearest example of this type in Hawaiian waters 

 is Sergestes vigilax and S. armatus, where most 

 juvenile S. armafus in the 6- to 8.5-mm CL range 

 live around 100 to 150 m at night, overlapping 

 somewhat with adult 5. vigilax in the same size 

 range (most 5. vigilax live above 100 m, but adults 

 often occur somewhat deeper). However, it ap- 

 pears that adult 5. vigilax are most abundant from 

 October to March, while juvenile S. armatu.-^ in the 

 same size range are most abundant from April to 

 June (Figures 6, 8). Thus the actual overlap at any 

 one time is probably small. 



The Hawaiian sergestid assemblage can thus be 

 described by size, morphology, and vertical dis- 

 tribution. Consider the half-red species first. Those 

 with short maxillipeds are divided into a pair of 

 species with lensed cuticular photophores and 

 three species with organs of Pesta. The pair with 

 cuticular photophores includes a large species, 

 Sergiafulgens, and a small species, S. scintillans; 

 these species may also live at different depths at 

 night. Of the three species with organs of Pesta, 

 Sergestes erectus is very large, distantly related to 

 the other two, and lives deeper at night; 5. atlan- 

 ticus is larger than S. cornutus and may live 

 deeper during the daytime. Long third maxillipeds 

 appear to have evolved at least twice, possibly 

 three times, in Sergestes (Burkenroad 1937; Foxton 

 1972). The 5. sargassi-S. pectinatus pair is distinct 



from the others; again, 5. sargassi is large and 5. 

 pectinatus is small, with specialized maxillipeds 

 and broader vertical distributions day and night. 

 The other two groups are more closely related, but 

 the S. armatus-S. vigilax pair has longer maxil- 

 lipeds than the S. orientalis-S. tantillus-S. conso- 

 hrinus triad. Sergestes armatus is larger than 5. 

 vigilax and lives deeper at night; the other group 

 has been discussed above. 



Among the all-red Hawaiian sergestids, a 

 similar organization prevails. The Sergia in- 

 equalis-S. bigemmea-S. gardineri group are re- 

 spectively large, medium-sized, and small; in 

 addition, S. gardineri lives shallower than the 

 other two at night, and perhaps during the day- 

 time. The 5. hisidcata-S. maxima pair is related to 

 the above triad, but S. hisulcata is somewhat 

 larger than 5. inequalis and lives deeper at night, 

 while the rare S. maxima is extremely large. Two 

 species without photophores are nonmigrators; S. 

 tenuiremis is much larger than Petalidium suspi- 

 riosum. The rare 5. laminafa, while related to S. 

 tenuiremis, is smaller, has photophores (Walters 

 1975), and appears to migrate. 



Studies of sergestid assemblages in the sub- 

 tropical Atlantic by Foxton (1970) near Fuerte- 

 ventura (Canary Islands) and Donaldson (1975) 

 near Bermuda showed interesting parallels to the 

 present study in the subtropical Pacific (Table 9). 

 The two Atlantic areas were verv similar to one 



Table 9.-Atlantic and Hawaiian sergestid assemblages. 



Hawaii 



Sergestes consobrinus 

 Sergestes orientalis \ 

 (Sergestes tantillus) f 



Sergestes armatus 

 Sergestes vigilax 



Sergestes atlanticus 

 (Sergestes cornutus) 



Sergestes erectus 



Sergestes sargassi 

 Sergestes pectinatus 



Sergia fulgens 

 Sergia scintillans 

 Sergia gardineri \ 

 Sergia bigemmea J 

 Serga inequalis 

 Sergia bisulcata \ 

 Sergia maxima J 



(Sergia laminata) 

 Sergia tenuiremis 



n.e. 



Petalidium suspiriosum 



Bermuda' 



(Sergestes edwardsii) 



Sergestes armatus 

 Sergestes vigilax 



Sergestes atlanticus 

 Sergestes cornutus 

 "Sergestes corniculum' 



Sergestes sargassi 

 Sergestes pectinatus 



(Sergia talismani) 

 n.e. 



Sergia splendens 

 Sergia robusta 



Sergia grandis 



(Sergia lillcta) 

 Sergia tenuiremis 



Sergia japonica 



'From Donaldson (1975). 

 2From Foxton (1970). 

 3n.e. — no equivalent. 

 <See text. 



Fuerteventura' 



n.e. 3 



n.e. 



Sergestes armatus 

 Sergestes vigilax 



(Sergestes atlanticus) 



n.e. 

 "Sergesfes corniculum' 



Sergestes sargassi 

 Sergestes pectinatus 



n.e. 

 n.e. 



Sergia splendens 

 Sergia robusta 



n.e. 



n.e. 

 Sergia tenuiremis 



Sergia japonica 



833 



