FISHERY BULLETIN: VOL. 77, NO 4 



epigastric tooth is found at the anterior 0.35 of the 

 carapace, and the hepatic spine lies conspicuously 

 ventral to the antennal spine; the postrostral 

 carina extends along anterior 0.55 of the carapace, 

 ending just posterior to the cervical sulcus; and the 

 anteroventral corner forms an angle of about 90°. 

 The antennular peduncle is 0.75 as long as the 

 carapace, the third article is 1.35 times the length 

 of the second, and the stylocerite is 0.4 that of the 

 first article. The scaphocerite falls slightly short of 

 the end of the antennular peduncle, and the ter- 

 minal spine of the lateral rib does not reach the 

 distal margin of the lamella. The low, sharp mid- 

 dorsal keel of the abdomen extends from the fourth 

 to the sixth somites, and the length of the latter is 

 1.7 times its maximum height. The thelycum is 

 depicted in Figure 23. 



In this species each spermatophore bears a con- 

 spicuous, somewhat rigid element which in im- 

 pregnated females lies over the plate of sternite 

 XIV (Figure 25). The paired elements, which pro- 

 ject from the mesial extremity of the sperm sacs 

 enclosed in the seminal receptacles, are joined 

 along their mesial margins and form a roughly 

 circular scale covering a large part of the plate. A 

 similar spermatophore is also found in P. balssi, 

 P. eduardoi, and P.jerryi, the other three Indo- 

 West Pacific species in which I have observed 

 impregnated females. 



Maximum lengths. — Males 25 mm cl, about 110 

 mm tl; females 31 mm cl, about 135 mm tl. 



Figure 25. — Penaeopsis rectacuta. i 25.5 mm cl, vicinity of 

 western Bohol. Philippines. Compound spermatophore attached 

 to female. Scale = 1 mm. 



and forms an angle with the lateral border, 

 whereas in P.jerryi it is strongly convex and con- 

 tinuous through a broad arc with the lateral bor- 

 der. Furthermore, the median plate of sternite 

 XIII is cordiform and rather elongate in P. rec- 

 tacuta and subsemicircular, or occasionally 

 trilobed in P. jerryi. 



Geographic and bathymetric ranges. — Indo-West 

 Pacific (Figure 6) from the Philippines (Bate 1881) 

 and Timor Sea to the south China Sea (north of 

 Borneo, Hall 1962). It has been found at depths 

 between 174 and 401 m. 



Affinities. — Two features of the carapace distin- 

 guish P. rectacuta from the closely allied, western 

 Indo-West Pacific P. jerry;: 1) the position of the 

 hepatic spine, which in the former is situated dis- 

 tinctly ventral to the antennal spine whereas it 

 occurs at about the same level in P.jerryi, and 2) 

 the length of the branchiocardiac carina which is 

 relatively short in P. rectacuta (its anterior ex- 

 tremity situated well behind the posterior end of 

 the hepatic sulcus) and is long in P. jerryi (its 

 anterior extremity located quite near the posteri- 

 or end of the sulcus). In addition, the thelycum of 

 P. rectacuta has the anterior border of the plate of 

 sternite XIV almost straight or slightly sinuous 



Variation. — This shrimp exhibits a rather 

 large number of morphological variations. In the 

 adult the rostrum may be straight, slightly convex 

 or sinuous, and the number of rostral teeth ranges 

 from 10 to 17. The scaphocerite falls short of, 

 reaches as far as or extends beyond, the antennu- 

 lar peduncle. In the females, the anterior border of 

 the plate of sternite XIV (Figure 24A , B ) varies 

 from transverse to slightly inclined posterolater- 

 ally, the median ridge may be short or extend to 

 the posteromedian projection of sternite XIII, and 

 the submedian depressions that flank the ridge, 

 although most often narrow, may be broad. Fur- 

 thermore, the setation of the plate, usually ex- 

 tending over the lateral portions, sometimes is 

 absent anteriorly and lacking posteriorly or vice 

 versa. The median plate of sternite XIII usually 

 bears a central depression, but occasionally the 

 latter extends across the entire width of the plate, 

 and the caudal margin of the posteromedian pro- 



746 



