EARLY STAGES OF PINK SHRIMP FROM FLORIDA WATERS 



347 



Table 3. — Corrtsponding stages in Penaeus duoramni and 

 P. setiferus — Continued 



Stage and struc- 

 ture 



Protozoca I— Con. 



Carapace 



width. 



Compound 



eyes. 

 Frontal orRans 

 Ocellus 



Labrum 



Labium. 



Antenna I.. 



Antenna II. 



Mandible. 



Maxilla I. 



MaxlUa II. 



P. duoTarum 



P. tetiferu) 



Maxllllped I.. 



n.35-0.44 mm 



Developing under cara- 

 pace. 



.\liscnt 



Present between develop- 

 ing compound eyes. 



Rouphly oval. Anterior 

 edge has large spine; 

 posterior margin .slight 

 notch and short bristles. 



2 lobed; extends from 

 under labrum; bristles 

 along median border of 

 lobes. 



Divided Into 3 major seg- 

 ments; with basal seg- 

 ment subdivided into 

 5 segments. Bears 8 

 setae. 



Protopod, 3 segments and 

 without setae. Endo- 

 pod, 2 segments and 

 9 setae. Eiopod. ap- 

 proximately 10 segments 

 and 13 setae. 



Has lost endopod and all 

 but trace of exopod. 

 Well-developed mastica- 

 tory surface. 



Maiilliped II.. 



Caudal furcae 

 and spines. 



Digestive 

 tract. 



Protopod has 2 segments; 

 endopod 3. Inner mar- 

 gins of these segments 

 lobed. Exopod (sca- 

 phognathite) is budlike. 

 Protopod has about 

 8 setae, endopod approx- 

 imately 9, and exopod 4. 



Larger than first maxilla. 

 Protopod has 4 lobed 

 segments and about 10 

 setae. Endopod has 5 

 segments with approxi- 

 mately 11 setae. Exopod 

 (scaphognathite) bud- 

 like and bears 6 setae. 



Largest of maxillae and 

 maxiUipeds. Protopod 

 has 2 segments (not 

 lobed), each segment 

 bearing 3 to 5 setae. 

 Endopod has 4 segments 

 and about 11 setae. 

 Exopod unsegmented 

 and bears 7 setae. Both 

 endopod and exopod 

 palplike. 



Smaller than first maxll- 

 llped. Protopod has 2 

 segments and about 5 to 

 7 setae. Endopod has 

 4 segments and 9 or 10 

 setae. Exopod unseg- 

 mented and bears 6 

 setae. 



Each furca bears 7 spines, 

 the most external of 

 which emanates from 

 dorsal surface. Longer 

 spines bear setules. 



Wider in anterior and pos- 

 terior portions than 

 between. 



0.36 mm. in first protozoea 

 with a body length of 

 0.86 mm. 



Same as In P. duorarum. 



Absent. 



Same as in P. duorarum. 



Anterior edge sharply 

 pointed; posterior edge 

 rounded and covers a 

 section of mandibles. 



No description given. 



Same as In P. duorarum. 



Protopod, 2 segments and 

 without setae. Endo- 

 pod, 2 segments and 

 8 setae. Exopod, 9 or 10 

 segments and 12 setae. 



Mandible modified Into 

 flattened plate with ser- 

 rated edge on iimer 

 margin. Both endopod 

 and exopod temporarily 

 lost. 



Protopod has 2 segments; 

 lobed on inner margins. 

 Each lobe bears aljout 

 4 setae. Endopod has 



3 segments and bears 

 8 setae. Several addi- 

 tional outer lateral setae 

 also present on endopod. 

 Exopod (scaphognathite) 

 a small lobe bearing 

 about 2 setae. 



Larger than first maxilla. 

 Protopod has iimer mar- 

 gin divided into 4 small 

 lobes each bearing 2 

 setae. Endopod has 4 or 

 Ssegmentseach with pair 

 of setae. Exopod (sca- 

 phognathite) knoblike 

 and bears 3 setae. 



Elongate biramous struc- 

 ture. Protopod has 2 

 segments and 4 setae. 

 Endopod has 9 segments, 

 each segment except dis- 

 tal bearing pair of setae. 

 Distal segment has 4 

 setae at the tip. Exopod 

 has single segment and 

 bears about 4 lateral and 



4 terminal setae. 

 Considerably smaller than 



the first. Protopod has 

 2 segments and 4 setae. 

 Endopod has 5 segments 

 and 10 setae. Exopod 

 has single segment and 

 bears 7 setae. 



Bifurcation of tall stronger 

 than In fifth nauplius. 

 Median notch made by 

 bifurcation is semlovate. 

 7 spines on each furca. 



Consists of oesophagus, 

 stomach, and IntestUie 

 and ends in anus which 

 opens somewhat ven- 

 trally at the apex of the 

 notch at the posterior 

 end of the body. 



' One of the 3 terminal setae of the exopod actually arises from a constric- 

 tion in the ramus approximately foiu'-fifths the distance from the body. 



The descriptions of tlie second and tliiid pro- 

 tozoea of /'. xctlfn us ;ne not detailed enough to 

 allow a tabular comparison of the two species. 

 The second protozoea measured from 1.5 to 1.9 

 mm. in P. (hiorai-vm compared with 1.3 to 1.7 mm. 

 in P. setiferuH. Measurements of the third pro- 

 tozoea were 2.2 to 2.7 mm. in tlie pink shrimp and 

 2.2 to 2.0 mm. in the w liite shrimp. 



From Pearson's drawinjj; (1939: fig. 9, p. 18) it 

 can be seen that (lie second jji-otozoea of P. sefi- 

 frriix lacks a seta at the junction of the distal two 

 segments on the posterolateral margin of the first 

 antenna. The corresponding stage of P. dnio- 

 riinim has a short seta at this location. Other- 

 wise, little difference can be noted at this stage 

 between the two species. 



The first and seco:>;l postlarval stages of P. duo- 

 rarum and P. setiferus are also very similar on the 

 basis of available descriptions. Pearson reports 

 that the supraorbital spines of the first postlarva 

 are still present, although reduced, while examina- 

 tion of that stage of P. duorarum reveals that the 

 spines are almost always missing. Size ranges of 

 these stages are similar. 



COMPARISON WITH P. AZTECUS 



Unfortunately, the laixal stages of the brown 

 shrimp. P. azfecus, have not been described. Pear- 

 son (1939) compared various-sized postlarvae that 

 he originally called P. hrirriJiemis (and, in a foot- 

 note, tentatively referred them to P. aztecus) with 

 similar-sized specimens of P. setiferus. He found 

 four principal characters separating the two spe- 

 cies in these stages. These cliaracters concern the 

 spination of the rostrum and the relationships of 

 the lengths of the rostrum and the third pereiopod 

 to the length of the eye. 



Williams (1959) reviewed the characters de- 

 scribed by Pearson and i)resented a provisional 

 key which could be used to distinguish the post- 

 larvae of P. setiferus. P. nztenis. and P. duorarum, 

 under 12 mm. total length. In this key, a differ- 

 ence is noted lietween tlie antennal scales of the 

 young postlarvike of the latter two species. In P. 

 iizterus. the antennal scale is "nearly unifonn in 

 shape with the lateral spine extending beyond the 

 broadly rounded tij)," wliile in P. duoraruni, "the 

 tip was more, or less acutely romided with the apex 

 near the mesial aspect of the tip. The lateral 



