FISHERY BULLETIN: VOL, 77, NO, 4 



posterior margin straight or emarginate. Sternite 

 XII armed with posteromedian subconical tooth 

 (apex slightly displaced anteriorly and sometimes 

 produced in slender spine) and bearing narrow 

 median carina; oblique pair of ridges extending 

 posterolaterally from base of tooth. 



Spermatophore similar to that of P. rectacuta 

 (see p. 746). 



Maximum lengths. — Males 30 mm el, 128 mm tl; 

 females 37 mm cl, 150 mm tl. 



Geographic and bathymetric ranges. — Indian 

 Ocean, off the coast of Africa (Figure 6), from 

 Somalia to Natal, South Africa, and also off 

 Madagascar, at depths between 280 and 977 m 

 (northernmost record and rnaximum depth from 

 Balss 1925). The records of this species, as well as 

 those of P. jerryi, from Madagascar are not in- 

 cluded in Figure 6, because Crosnier and Jouan- 

 nic (1973) reported the occurrence of these 

 shrimps and their bathymetric ranges in the sur- 

 rounding waters, but did not cite the localities at 

 which they have been found. 



Affinities. — Penaeopsis balssi can be distin- 

 guished readily from other members of the genus 

 by the usually strongly arcuate and short ros- 

 trum, which in adults does not surpass midlength of 

 the second antennular article; in the other species 

 it is straight, slightly sinuous or only somewhat 

 arched, and overreaches the second article or 

 often even the peduncle. The structure of the 

 genitalia in P. balssi is closer to that of P. rec- 

 tacuta than to those of its other congeners. In the 

 petasma of P. balssi, however, the rather flexible, 

 distolateral part of the ventrolateral lobule is 

 broad, and the ventral costa terminates apically 

 in a broad, neeirly rounded process, whereas in 

 that of P. rectacuta the distolateral part is rela- 

 tively narrow, and the ventral costa terminates 

 in a much narrower process. Furthermore, the 

 proximal process of the dorsolateral lobule is sub- 

 oval and directed mesially in P. balssi, whereas in 

 P. rectacuta it is nearly circular and extends prox- 

 imally. The thelycum in P. balssi has the plate 

 of sternite XIV flat to strongly convex laterally 

 instead of slanting directly from the border as it 

 does in P. rectacuta, and its median ridge is more 

 prominent caudally than in the latter species. 

 These two shrimps differ also by the anteroven- 

 tral angle of the carapace, about 90° in the latter 

 and obtuse in P. balssi. 



Variation. — In this species the rostrum is usually 

 strongly arched, but in occasional specimens it is 

 only sightly so; the number of rostral teeth 

 ranges from 8 to 12, and although in most speci- 

 mens the second tooth is situated opposite the 

 orbital margin, in some, the third tooth oc- 

 cupies this position so that two teeth, instead of 

 one, are on the carapace. As in P. rectacuta, the 

 scaphocerite falls short of, reaches, or over- 

 reaches the end of the antennular peduncle. In 

 males the distomedian projections of the petas- 

 ma may be asymmetrical (Ivanov and Hassan 

 1976), and in some their free margin is scalloped; 

 also the rounded distolateral portion of the ven- 

 trolateral lobule occasionally is conspicuously 

 expanded distally. In females, the thelycal plate 

 of sternite XIV varies from nearly flat to strongly 

 convex laterally, and the median ridge may ex- 

 tend to, or end before reaching, the posterome- 

 dian projection of the median plate of sternite 

 XIII; the latter plate may be subtriangular, cor- 

 diform, or orbicular, and its projection has the 

 caudal margin either straight or shallowly emar- 

 ginate; also, the posteromedian tooth of sternite 

 XII, often low conical, may be produced into a 

 rather long apical spine directed anteriorly. 



Remarks. — According to Boris G. Ivanov (see 

 footnote 2) the coordinates provided by Ivanov 

 and Hassan (1976) for Van Gogh stn 34, where 

 two female and two male paratypes were ob- 

 tained, were incorrect, that the latitude should 

 have been cited as 25'23' S instead of 23 23' S. 



Ramadan (1938) illustrated the thelyca of an 

 adult and two juveniles in different stages of 

 development. In the juveniles, the submesial de- 

 pressions are represented by paired pits, and the 

 median plate of sternite XIII is well defined and 

 produced into a sharp, slender, apical spine. This 

 latter feature is not included in Ramadan's illus- 

 trations but was observed by me during the 

 examination of the juveniles available to Rama- 

 dan, which range in size from 8 to 12 mm cl. 



Penaeopsis challengeri De Man 1911 



Figures 6-10 



Penaeus serratus Bate 1881:182 [lectotype, by 

 present action, V, BMNH 1978.323; type- 

 locality, off Matuku, Fiji Is., 19°09'35" S. 

 179°41'50" E, 315 fathoms (576 m). Chal- 

 lenger stn 1731; 1888:268 [part], pi. 37, 



728 



