GORE: LARVAL DEVELOPMENT OF GALATHEA ROSTRATA 



Pereiopods: Well formed, completely segmented 

 and chelated, protruding almost totally from 

 under posterolateral carapace margins. 



Abdomen: Somites 2-5 each with a pair of undi- 

 vided pleopod buds, gradually lengthening as 

 stage progresses, but never becoming bifid. 



Color: Similar to regular stage IV zoeae. 



Remarks: The zoeae in this stage are much more 

 developed morphologically, possessing a different 

 arrangement of antennular aesthetascs, a well- 

 developed antennal endopodite, mandibular 

 palps, segmented and chelated pereiopods, and 

 distinct (but undivided) pleopod buds. These zoeae 

 molt directly to megalopae, bypassing stage V 

 completely. 



Fifth Zoea 



Carapace length: 1.6 mm 

 Number of specimens examined: 8. 



Carapace: (Figure 2E, e). Rostral spine with 

 lateral margins appearing somewhat embossed at 

 posterolateral angle of zoeal orbit; carapace lat- 

 eral margins deeply rounded, convex posterolat- 

 erally, unarmed; posterior spine recurved ventral- 

 ly in some specimens, nearly straight in others, 

 inner margin of same curving regularly inward to 

 deeply excavated dorsomedial margin of carapace; 

 latter entirely without armature. Eyes large, 

 ovoid, on well-developed elongate stalks. 



Antennule: (Figure 7A). Exopodite with five 

 rows of aesthetascs laterally: 2, 3, 3, 3, 2, plus 3 

 and 3 setae at tip. Endopodite from about 0.75 x to 

 just subequal in length to exopodite. Protopodite 

 segmented into elongate basipodite and truncated 

 coxopodite; former with a single long plumose seta 

 distally, plus 4 stout setae terminally at exopodite 

 junction, 3 more medially; latter with 2 stout setae 

 ventrally near line of segmentation. 



Antenna: (Figure 7B). Endopodite very notice- 

 ably longer than scaphocerite ( 1.3-1.4 x); latter 

 bearing 12-14 plumose marginal setae plus addi- 

 tional ventral marginal spinules as in earlier 

 stages. Larger propodal ventral spine less than 

 0.2 X endopodite length, smaller remains about 

 half the size of larger, both armed similarly as 



illustrated. Toward end of larval stage trans- 

 parent endopodite reveals distinctly segmented 

 megalopal antennal flagellum within endopodal 

 sheath. 



Mandibles: (Figure 7C). Noticeably dentate, 

 each with simple, distinct palp. 



Maxillule: (Figure 7D). Endopodite un- 

 changed from regular stage IV; basal setule may 

 not be present. Basal endite with 8 stout spines, 3 

 setae; coxal endite with 6 long spines, 3 strong 

 setae, and small tooth, placed as illustrated. 



Maxilla: (Figure 7E). Endopodite unchanged. 

 Basal endite distal lobe with 8 spines and strong 

 setae, 2 thin setae terminally, one regular seta 

 laterally; proximal lobe with 6 terminal, 2 sub- 

 terminal, 2 lateral processes, most appearing to be 

 strong setae and spines. Coxal endite distal lobe 

 with 2 spines, 2 strong apical setae, 2 thinner 

 subapical or lateral setae; proximal lobe with 

 about 13 spines and strong setae, progressing ter- 

 minally to laterally as 7, 4, 2. Scaphognathite with 

 about 22-25 marginal setae, including enlarged 

 plumose seta apically; 2 small setules present, 

 positioned laterally. 



Maxilliped 1 and 2: (Figures 7F, G). Little 

 changed from previous stage. 



Maxilliped 3: (Figure 7H). Little changed in 

 form from previous stage, except endopodite now 

 much larger, longer, extending well past distal 

 margin of basipodite; 3 setae as before. 



Pereiopods: (Figure 2E). Extremely large, ap- 

 pearing to be nearly functional, protruding be- 

 neath, and forcing posterolateral margins of 

 carapace, outward; walking leg segmentation and 

 cheliped chelation distinctly visible. 



Abdomen: (Figure 2E, e). Lateral spine on so- 

 mite 5, and that on posterodistal angle of somite 6, 

 the only armature. Pleopods present as 

 well-developed, bifid, buds. 



Telson: (Figure 71, i). Uropods well-developed, 

 both endopodite and exopodite with variable 

 number of marginal setae, usually 8-10, and 10-13 

 or occasionally 14, respectively. Telsonal fused 

 and movable processes as illustrated; fourth pro- 

 cess distinctly spinulose; occasionally an extra 



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