FISHERY BULLETIN: VOL. 69, NO. 3 



2 mm 



I I 



Figure 7, — Thelyca. A. Ti-achypeitaeus brevistiturae Burkenroad, 5 21.5 mm carapace length, off Zacapulco, Chia- 

 pas, Mexico. B. Trachypenaeiis hyrdi Burkenroad, 9 27 mm carapace length, Golfo de Panama, Panama (syn- 

 type). C. Trachypenaeus similis pacificus Burkenroad, 9 25 mm carapace length, Archipielago de las Perlas, 

 Golfo de Panama, Panama (syntype). 



tion of T. fuscina also applies to T. faoea: the 

 armature of the telson, the shape and pubescence 

 of the platelike base of the anterior part of 

 sternite XIV in females, the marginal contour 

 of the median plate of sternite XIII in males, and 

 perhaps color. 



In T. faoea the posteriormost of the four pairs 

 of spines on the telson (Figure ."jB) are movable 

 instead of fixed, and shorter than those of T. 

 fuscina, the ratio length of spine/width of term- 

 inal portion = 0.40 (A^47: 0.75-0.20); the other 

 three pairs of movable spines, including those 

 located at the lateral base of the posteriormost 

 spines, are minute, actually microscopic. In T. 

 faoea the median sulcus of the telson is deep 

 anteriorly but hardly perceptible or indistinct 

 posteriorly. 



In males of T. faoea the median plate at the 

 posterior margin of sternite XIII (Figure 4G) 

 usually varies from subtrajjezoidal (widest an- 

 teriorly) to suhorbicular. In females, the struc- 

 ture of the thelycum (Figure 5B) is similar to 

 that of T. fuscina; however, lateral margins of 

 the platelike base of the anterior part of sternite 

 XIV are almost straight, not or barely curving 

 posteromesially, forming about 90° angles with 



projections of the posterior part; furthermore, 

 the lateral areas of that platelike portion are 

 studded with rather densely set setae, the latter 

 extending onto basal portions of the flaps. 



Avila and Loesch (1965) described the color 

 of recently preserved juvenile specimens of T. 

 faoea as dark blue or purple with light uropods. 

 They noticed that specimens preserved for 2 days 

 in b'/r Formalin exhibit a clear, horse-shoe 

 shaped band on the first three abdominal somites, 

 which is open anteriorly. These observations 

 were based on material from Ecuador and differ 

 from those made by me on T. fuscina. Recorded 

 notes on color are so limited that conclusions in 

 regard to differences in this character between 

 the two species must await further obsei'vations 

 throughout their ranges. 



DISTRIBUTION 



Although this species has been reported from 

 as far north as the coasts of Guatemala, El Sal- 

 vador and Costa Rica, the collections available 

 to me are limited to the area from Panama to 

 Ecuador. Examination of additional samples of 



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