Appendix masculina (Figure ID) minute, 

 somewhat oval, bearing distal patch of setae; 

 thickening at its base, inconspicuous. 



Thelycum (Figure 2A-C) with anterolateral 

 borders of plate of sternite XIV varying from 

 slightly concave to convex, and separated by pos- 

 teromedian projection of sternite XIII; plate 

 strongly slanting dorsomesially, its surface flat or 

 each side biconvex ventrally. Lateral borders 

 slightly concave, strongly converging posteriorly, 

 not reaching posterior ridge but separated from it 

 by deep depression, latter extending anteriorly 

 adjacent to median rib and merging with an- 

 teromedian depression; median rib broadest bas- 

 ally, gently tapering toward, hut not reaching, 

 posteromedian projection of sternite XIII. Median 

 plate of XIII trilobed to cordiform, slightly to pro- 

 nouncedly elongate, covered with setae (most lost 

 in specimen illustrated in Figure 2Cl except for 

 naked central concavity, setae directed anteriorly 

 except on base of posteromedian projection where 

 directed caudally; posteromedian projection short, 

 with caudal margin straight or shallowly emargi- 

 nate. Sternite XII bearing small posteromedian 

 tooth and pair of sharp ridges, extending pos- 

 terolaterally from base of tooth. 



D 



isCLis.sion 



In several features the three specimens are 

 markedly similar to members of P. rectacuta ( Bate 

 1881). The rostrum (Figure 3) is straight and its 



second tooth is located in line with the orbital 

 margin, the anteroventral angle of the carapace is 

 approximately 90°, and the moderately long bran- 

 chiocardiac carina is conspicuous, its anterior ex- 

 tremity not nearly reaching the posterior end of 

 the hepatic sulcus. Also the relative length of the 

 pereopods and — in the two smaller animals — the 

 shape of the median plate of sternite XIII are simi- 

 lar to those in P. rectacuta. Furthermore, the three 

 shrimps were collected together with specimens of 

 the latter species, all three in localities where the 

 only other Penaeopsis occurring in the area (P. 

 eduardoi Perez Farfante 1977) was not taken — 

 another indication that these shrimp probably be- 

 long to P. rectacuta. 



The petasma and the thelycum of these shrimp 

 are different from those of other species of 

 Penaeopsis, including those of P. rectacuta. The 

 ventral costae of the petasma (Figure IB-C), ta- 

 pering distally into a short projection disposed at 

 an obtuse angle to the shaft, differ from those of 

 adult males of P. rectacuta in which the ventral 

 costae turn abruptly at right angles and bear a 

 thin marginal border that is bent inward. In the 

 three specimens the petasma somewhat resembles 

 that of large juveniles (with a carapace length of 

 about 13 mm) of P. rectacuta (Figure lE-F); how- 

 ever, in the latter the distomedian projections are 

 less distinct than they are in my specimens or in 

 adult P. rectacuta. Also, in juveniles of P. rectacuta 

 the ventral costae do not taper distally into free 

 projections, instead the tips are broad and turned 



Figure 2.~Penaeopsis sp. Thelyca. A, USNM 170582, 24.5 mm cl, Bohol Strait. A/iofro.ss stn 5419. B, USNM 170581, 23 mm cl. Bohol 

 Strait, A /6a ^rosi- stn 5418. C, USNM 170580, 19 mm cl, Gulf of Davao, Mindanao, Philippmes, Albatross stn 5247. 2 mm indicated. 



688 



