PEREZ FARFANTE: KEY TO AMERICAN PACIFIC SHRIMPS, GENUS Trachypintatus 



2 mm 



Figure 5. — Thelyca. A. Trachypenaens fuscina sp. n., 9 34.5 mm carapace length, off Barra de San Marcos, 

 Chiapas, Mexico. B. Trachypenaens faoea Loesch and Avila, $ 32.5 mm carapace length, Ensenada de Garachine, 

 Golfo de Panama, Panama. 



flaps setose. Median plate of sternite XIII large, 

 oval, strongly concave ventrally, with margin 

 tumid, and bearing setae; plate extending poster- 

 iorly joining dorsal wall of flaps, thus giving 

 rise to median pocket; latter bearing paired aper- 

 tures of internal seminal receptacles laterally 

 (Figure 6B). In impregnated females, median 

 pocket occupied by sclerotized, sperm-free, 

 brownish component of spermatophores, extend- 

 ing almost to anterior margin of median plate. 

 Hardened, glutinous material, extruded with 

 spermatophores, protruding through slit between 

 flaps, forming plug on ventral surface of flaps. 

 Internal seminal receptacles (Figure 6A, B) 

 consisting of paired, longitudinally arranged, 

 trilobed, membranous sacs: single, large, post- 

 erior lobe, dorsal to median pocket, extending 

 caudally almost to posterior margin of sternite 

 XIV; and two small lobes, one directed antero- 

 mesially, dorsal to median plate, and the other 

 laterally, dorsal to small hood of sternite XIV. 



2 mm 



2 mm 



Figure 6. — Trachypevaeus fuscina sp. n. A. Seminal re- 

 ceptacles (dorsal view), 9 39.5 mm carapace length, off 

 Salina Cruz, Oaxaca, Mexico. B. Left seminal receptacle 

 (ventral view), 9 31 mm carapace length, mouth of Rio 

 Suchiate, Chiapas, Mexico. 



641 



