FISHERY BULLETIN: VOL, 69. NO. 2 



total length unless otherwise indicated) were 

 made in Va-cm units on a measuring board so 

 adjusted that when the y^^-cm units were con- 

 verted to millimeters the midpoints fell on 3 and 

 8 (e.g., a length of 25 Y^-cm units represents 

 lengths between 121 and 125 mm with midpoint 

 at 123 mm; similarly, the midpoint in milli- 

 meters for 26 Vi-cm units is 128 mm). Cara- 

 pace lengths (orbital angle to mid-dorsal end of 

 carapace) were measured with calipers to the 

 nearest millimeter. Both total length and car- 

 apace length measurements were made of fresh- 

 ly caught specimens. 



The ovarian stages, determined by visual in- 

 spection at the time each female was measured, 

 were based on size and color of the ovaries. 

 We also noted whether spermatophores were 

 attached to females. 



SYSTEMATICS 



In the shrimp family Penaeidae the royal red 

 shrimp, Hymenopenaeus robustus Smith, be- 

 longs in the subfamily Solenocerinae, which is 

 distinguished from the three other subfamilies 

 by having a postorbital spine (Figure 3). 



ORBITAL ANGLE 

 TOOTH OR SPI 



POS 



BRANCHIOSTEGAL SPINE 



Figure 3. — Outline of carapace of H. rohustjts showing 

 position of spines. 



Three genera (Haliponis Bate, Hymenopen- 

 aeus Smith, and Solenocera Lucas) make up the 

 subfamily Solenocerinae. Solenocera is distinct 

 from the other two genera in having the anten- 

 nular flagella flattened or hollowed out — chan- 

 nellike in structure — rather than cylindrical and 

 filiform. Hymenopenaeus has a single pair of 

 lateral telson spines and lacks podobranchs be- 

 hind segment VIII, whereas Hnliporus has sev- 

 eral pairs of lateral telson sjjines and podo- 

 branchs posterior to segment VIII. 



Within the genus Hymenopenaeus, three spe- 

 cies (H. rohiistus, H. modestus Smith, and H. 

 lucasii Bate) are separated from all other species 

 by the following combination of characters: 

 branchiostegal spine present, pterygostomian 

 spine absent, and no postrostral teeth separated 

 from the rostral group (Figure 3). 



H. robustus is distinct from H. modestus and 

 H. lucasii in having a tooth or spine in the or- 

 bital angle (Figure 3). 



BIOLOGY OF THE SHRIMP 

 REPRODUCTIVE SYSTEMS 

 Internal 



The internal reproductive organs of royal red 

 shrimp are so similar to those described by 

 Angelescu and Boschi (1959) for Hymenopen- 

 aeus muelleri and by King (1948) and Young 

 (1959) for the white shrimp, Penneus setiferus, 

 that only gross anatomy is given here. 



The ovaries are paired. In the cephalothor- 

 acic region they are partly fused; each ovary 

 has an anterior pointed lobe and 6 to 8 finger- 

 like lateral projections which lie over the hepa- 

 topancreas. A lobe from each ovary extends 

 nearly the full length of the abdomen dorsolat- 

 eral to the intestine. The oviducts lead to gen- 

 ital pores at the bases of the third pereiopods 

 (Figure 4). 



The testes are also paired and occupy a po- 

 sition in the cephalothoracic region similar to 

 that of the ovaries. Each testis has several 

 lateral lobes, and a looped vas deferens which 

 connects to the terminal am])oule on the coxa 

 of the fifth pereiopod. The testes do not extend 

 into the abdomen. 



External 



Details of the structure of the thelycum in 

 the female (considered to be modifications to 

 the sternal plates of somites XII, XIII, and XIV) 

 are shown in Figure 4. Note the bristly, cuplike 

 paired openings of the oviducts at the bases of 

 the third pereiopods; the rectangular plate with 



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