FISHERY BULLETIN; VOL, 77, NO. 4 



much larger proximal one, latter raised mesially 

 in conspicuous crest; rib of dorsolateral lobule 

 terminating proximally in subcircular process. 

 Ventrolateral lobule bearing flexible, roughly 

 triangular, subterminal projection distolaterally; 

 ventral costa continuing beyond projection, curv- 

 ing gently dorsomesially, and forming moder- 

 ately long blunt spine (free from, although closely 

 appressed to, margin of dorsolateral lobule), not 

 reaching level of row of cincinnuli. 



Appendix masculina (Figure 9C) transversely 

 oval (considerably broader than long), strongly 

 convex dorsally, and with about two-thirds of dor- 

 sal surface covered with short setae. 



Thelycum (Figure lOA, B ) with anterior border 

 of plate of stemite XIV strongly arched (delimit- 

 ing broad lobes) on each side of posteromedian 

 projection of sternite XIII, and bearing long setae, 

 latter also present along lateral borders; plate 

 raised in paired submesial elevations separated 

 anteriorly by deep depression, sometimes inter- 

 rupted by low median ridge, and bearing pos- 

 teromedian, strong, subrectangular protuberance 

 armed with anterior, compressed tooth. Median 

 plate of sternite XIII roughly pentagonal, setose, 

 bearing central depression continous with me- 

 dian groove reaching, or almost reaching, apex; 

 posteromedian projection short, with posterior 

 margin entire, Sternite XII armed with small 

 subconical, posteromedian tooth and oblique 

 paired ridges across posterior border. 



Maximum lengths. — Only male available, a 

 juvenile 14 mm cl, 65 mm tl; lectotypic female, 24 

 mm cl, 114 mm tl. 



Geographic and bathymetric ranges. — Known 

 only from the type-locality, off Matuku, Fiji Is- 

 lands, (lat. 19°09'35' S, long. 179°4r50" E), 576 

 m. Challenger stn 173 (Figure 6). 



Affinities. — The affinities of P. challengeri and P. 

 balssi are evident in the rostrum, which in both is 

 arched (although considerably more so in the lat- 

 ter) and deep basally, and in the telsonic arma- 

 ture, which consists of two pairs of movable 

 spines in addition to the fixed pair. Penaeopsis 

 challengeri, however, differs strikingly from P. 

 balssi, as well as from its other congeners, in the 

 unique structure of the external genitalia. In 

 males of P. challengeri the ventrolateral lobule of 

 the petasma bears a flexible, roughly triangular 

 process which does not extend beyond the level of 



Figure 10.— Penaeopsis challengeri. a, 9 22 mm cl, off Matuku, 

 Fiji Islands. Thelycum, ventral view. B, Lectotype. Thelycum, 

 ventrolateral view (> lirs not shown). Scales = 1 mm. 



the tip of the ventral costa, and the latter ends 

 distally in a spine similar to, but shorter than, 

 that of P. eduardoi. The proximal process of the 

 rib of the dorsolateral lobule is subcircular in P. 

 challengeri like that in P. eduardoi and P. rec- 

 tacuta, but different from the transversely oval 

 one in P. balssi. In females of P. challengeri the 

 plate of stemite XIV is produced in paired, broad 

 anterior lobes, is raised ventrally in a pair of lon- 

 gitudinal, submesial elevations, and bears a sub- 

 rectangular posteromedian protuberance some- 

 times continuing anteriorly as a weak, depressed 

 ridge. In the other species the plate, if produced, 

 forms only small anterior lobes, is flat or (in P. 

 balssi) raised in lateral, rather than submesial. 



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