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DESCRIPTION OF LARVAE OF A HIPPOLYTID SHRIMP, LEBBEUS GROENLANDICUS, REARED IN SITU IN KACHEMAK BAY, ALASKA EVAN HAYNESl ABSTRACf Larvae ofLebbeus groenlandicus, a hippolytid shrimp, were reared in situ in Kachemak Bay, Alaska, from the first zoea (Stage 1) through the megalopa (Stage III). Each ofthe three stages is described and illustrated, and then compared with descriptions of larvae of Lebbeus spp. given by other authors. Information on the larval stages ofthe genus Leb­ setae are shown. The terms are defined as follows: beus is meager. Pike and Williamson (1961), in their summary of the generic characteristics of setose - set with bristles (setae) Spirontocaris and related genera, note that the spinose - bearing many spines only larva ofLebbeus known for certain is a larva spinous - spinelike of L. polaris dissected from a well-developed egg. spinulose - set with little spines. During studies on rearing larvae of pandalid shrimp for descriptive purposes (Haynes 1976, The figures are in part schematic and represent 1978), I succeeded in rearing larvae of L. groen­ typical setal counts. landicus to the megalopa stage. This report de­ scribes and illustrates each ofthe two zoeal stages STAGE I ZOEA and megalopa ofL. groenlandicus, and compares the stages obtained from rearing in situ and from Total length of Stage I (Figure 1A) 6.9 mm plankton in Kachemak Bay with provisionally (range 6.4-7.4 mm; 10 specimens). Live specimens identified larvae of L. groenlandicus reported by characterized by bright orange color extending other authors. along ventral surface of body from antennules to fourth abdominal segment, orange gut, small METHODS orange chromatophore at anus, and greenish in­ ternal thoracic organs; remainder of zoea trans­ A complete discussion of rearing technique, lucent. Rostrum slightly sinuate, without teeth, methods of measurement, techniques of illustra­ about two-thirds length of carapace. Carapace tion, and nomenclature ofgills and appendages is with dorsal rounded prominence at base of ros­ given by Haynes (1976). Briefly, the rearing trum and near posterior edge; no supraorbital technique consists ofobtaining Stage I zoeae from spines. Usually at least two minute spinules occur known parentage in the laboratory and then rear­ along ventral margin of carapace immediately ing the zoeae to postlarvae in 500-ml flasks sus­ posterior to pterygostomian spine. pended upright beneath the surface of the sea. Cast skins and larvae removed from the flasks ANTENNULE (FIGURE 1B).-First antenna, or were examined in the laboratory to determine antennule, consists ofan unsegmented cylindrical sequence and morphology of each stage. Larval basal portion and two distal conical projections; stage was also verified using larvae from plankton largest conical projection bears four aesthetascs of reared in the same manner as larvae obtained in various lengths; smallest conical projection bears the laboratory. a single heavily plumose seta. In the illustrations (Figures 1-3), for clarity, setules on setae are usually omitted but spinulose ANTENNA (FIGURE 1C).-Consists of inner flagellum (endopodite) and outer antennal scale (exopodite). Flagellum two-segmented, about INorthwest and Alaska Fisheries Center Auke Bay Labora­ tory, National Marine Fisheries Service, NOAA, P.O. Box 155, twice length of scale; distal segment styliform and Auke Bay, AK 99821. terminating in narrow projection. Two simple Manuscript accepted November 1977. 457 FISHERY BULLETIN: VOL. 76, NO.2. 1978. FISHERY BULLETIN: VOL. 76, NO.2 1.0 mm A B 0.5 mm <- C l- e ( ( c.. ( \, \ \ cc" , ( \ \ , ( ( LEFT RIGHT c D 0.5 mm 0.25 mm FIGURE l.-Stage I zoea of Lebbeus groenlandicus: A, whole animal; B, antennule; C, antenna; D, mandibles (right and left). 458 HAYNES: LEBBEUS GROENLANDlCUS LARVAE E 0.25 mm 0.25 mm , , 0.5 mm H 1.0 mm FIGURE l.-Stage I zoeaofLebbeusgroenlandicus: E, maxillule; F, scaphognathiteofmaxilla; G, firstmaxilliped; H, second maxilliped. setae occur at joint. Antennal scale distally di­ margin. Protopodite bears two simple spines ven­ vided into four segments (proximal joint often in­ trally, one at base of flagellum and one at base of complete) and fringed with 11 heavily plumose scale. setae along terminal and inner margins. A small seta often occurs proximally near lateral MANDIBLES (FIGURE ID).-Without palps; 459 FISHERY BULLETIN: VOL. 76. NO.2 J 0.5 mm /- ..... , / \ / \ I \ / \ I \ / \ / \ / \ / " - ....... _". L M 0.5 mm 1.0 mm FIGURE l.-Stage I zoea ofLebbeus groenlandicus: I, third maxilliped; J, first pereopod; K, third pereopod, L, first pleopod; M, second pleopod; N, telson. well developed. Incisor process of left mandible mandibles bear well-developed denticles along bears five teeth, one ofthem located near movable terminal margin. Truncated end of molar process premolar denticle Oacinia mobilis), in contrast to ofright mandible formed into curved lip. Only left triserrate incisor process of right mandible. Both mandible bears a subterminal process. 460 HAYNES: LEBBEUS GROENLANDICUS LARVAE MAXILLULE (FIGURE lE).-First maxilla, or SECOND PEREOPOD.-Similar in shape to first maxillule, bears coxal and basial endites and an pereopod except narrower, exopodite smaller, and endopodite. Proximal lobe (coxopodite) bears 15 chela more deeply cleft. setae, most of them spinulose. Median lobe (basipodite) bears 24 spines terminally, 9 ofthem THIRD (FIGURE 1K) TO FIFTH PEREO­ spinulose; and 2 spines subterminally, 1 of them PODS.-Each pair essentially identical except plumose and the othersimple. A series offine hairs that they decrease slightly in size from third to occurs in vicinity of the simple spine. Endopodite fifth. No exopodites. originates from lateral margin of basipodite and bears three terminal and two subterminal PLEOPODS.-First pleopod (Figure 1L) slightly spinulose setae. No evidence of outer seta on cleft, without joints or setae. Second pleopod (Fig­ maxillule. ure 1M) bilobed; outer lamella segmented; inner lamella usually only partially segmented but MAXILLA (FIGURE 1F).-Bears platelike bears bud of appendix interna. Third to fifth exopodite (scaphognathite) with 33 long, plumose pleopods essentially identical to second pleopod setae along outer margin, and a longer, thick seta except both lamellae distinctly segmented. at the proximal end. Endopodite not segmented; setae spinous, setation formula 2, 2, 1,2,3. Both ABDOMEN AND TELSON (FIGURES lA, basipodite and coxopodite bilobed. Basipodite 1N).--Abdomen consists offive segments and tel­ bears 29 setae, 14 on distal lobe and 15 on proxi­ son (somite six is fused with telson in Stage n. mal lobe. Coxopodite bears 23 setae, 5 on distal Fourth and fifth abdominal segments each with lobe and 18 on proximal lobe. pair of posterolateral spines nearly as long as segments themselves. Telson slightly emar­ FIRST MAXILLIPED (FIGURE 1G).­ ginated distally; bears 19-21 densely plumose Protopodite segmented; bears 27 setae on distal setae; small spinules occur between bases of all segment and 8 on proximal segment, most ofthem setae except two outermost pairs. Enclosed spinulose. Endopodite four-segmented; setation uropods visible. Anal spine present. formula 4, 3, 3, 7. Basal segment of endopodite bears conspicuous setulose spine. Exopodite seg­ STAGE II ZOEA mented at base; bears four natatory setae. Epipo­ dite distinctly bilobed. Total length of Stage II 8.3 mm (range 8.1-8.7 SECOND MAXILLIPED (FIGURE 1H).­ mm; 8 specimens). Color similarto StageI zoea but more diffuse. Rostrum (Figure 2A) arched upward; Protopodite not segmented; bears nine setae, five of them spinulose. Endopodite five-segmented; slightly blunter than in Stage I; without teeth. fourth segment expanded somewhat laterally; Carapace bears supraorbital, antennal, and pterygostomian spines in addition to several terminal segment tipped by five setae and bears single seta subterminally; basal segment bears spinules along anteroventral margin. conspicuous setulose spine like that on basal seg­ ment of endopodite of first maxilliped; setation ANTENNULE (FIGURE 2B).-Shows considera­ formula 6, 4, 2, 3, 4. Exopodite about three times ble change from Stage 1. Largest conical projection longer than endopodite; bears five natatory setae. segmented at tip; terminal segment bears three Epipodite present but not bilobed. setae ofdifferent lengths; proximal segment bears six groups of five aesthetascs each in addition to THIRD MAXILLIPED (FIGURE 1I).­ row of four aesthetascs laterally and single seta Protopodite not segmented; bears three setae. En­ distally. Smallest conical projection bears three dopodite five-segmented; as long as exopodite; nonplumose setae, one long and two short. Pedun­ number of setae somewhat variable. Exopodite cle ofantennule rounded laterally, not segmented, bears five natatory setae. No epipodite. and bears five plumose setae that originate ven­ trally. FIRST PEREOPOD (FIGURE 1J).-Endopodite relatively short, wide, and partially segmented; ANTENNA (FIGURE 2C).-Flagellum of an­ chela partially formed; dactylopodite bears three tenna still two-segmented, but slightly stouter simple spines. Exopodite a small lobe. and projection at tip smaller than in Stage I; a few 461 FISHERY BULLETIN: VOL. 76, NO.2 0.5 mm 0.5 mm 0.5 mm 0.5 mm FIGURE 2.-Stage II zoea of Lebbeus groenlandicus: A, carapace; B, antennule; C, antenna; D, first pereopod; E, second pereopod; F, second pleopod. 462 HAYNES, LEBBEUS GROENLANDICUS LARVAE small setae occur along lateral margin. Antennal PLEOPODS.-First pleopod slightly more

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