BULLETIN OF MARINE SCIENCE, 42(1): 101-132, 1988
LARVAL DEVELOPMENT OF THE SPECKLED SWIMMING CRAB, ARENAEUS CRIBRARIUS (DECAPODA: BRACHYURA: PORTUNIDAE) REARED IN THE LABORATORY
Kenneth C. Stuck and Frank M. Truesdale
ABSTRACT Eight zoeal stages and a megalopa of the speckled swimming crab, Arenaeus cribrarius, are described and figured from larvae of an ovigerous specimen collected at Hom Island, Mis- sissippi (Gulf of Mexico). Crab stages 1-3 are also briefly described. Larvae were reared at 25°C and 300/00salinity; some individuals completed zoeal development in 30 days,and reached crab I, 13 days later. Zoea I characters of A. cribrarius are compared with those of seven other species of shallow water Gulf Portuninae, from larvae reared by the authors, and from the literature. Antennal and telson features are important in distinguishing among zoeae I ofGulfPortuninae. Characters ofzoeae II-VIII and the megalopa of A. cribrarius and those of corresponding stages of Callinecles sapidus, C. similis. and PorlUnus spinicarpus from the literature are compared. In zoeae III and VI, setation of maxillar basal and coxal endites is a distinguishing feature among A. cribrarius, C. sapidus, C. similis, and P. spinicarpus, and in zoea V, maxillular basal and coxal endite setation distinguish each. Antennular aesthetasc formula distinguishes each species having a zoea VIII, and in all zoeal stages this feature distinguishes A. cribrarius from the others. Zoeae IV and VII of C. sapidus, C. similis and P. spinicarpus can be separated by setation of maxillular basal and coxal endites, and in zoea II this same feature distinguishes P. spinicarpus from C. sapidus and C. similis. Zoeae II of C. sapidus and C. simi/is from Atlantic stocks can be separated by maxilliped I endopod setation, but zoeae II of these species from the Gulf are presently inseparable. The megalopa of A. cribrarius is larger (carapace width, length) than those ofthe other three species. Megalo- pae of all four species can be reliably separated by number of hooked setae on pereopod 5 dactylus. The spawning season of A. cribrarius in the Gulf of Mexico extends at least from mid-April to mid-October.
The speckled swimming crab, Arenaeus cribrarius (Lamarck, 1818), is known from Vineyard Sound, Massachusetts, to La Paloma, Uruguay (Juanico, 1978; Williams, 1984). Although a large crab, up to 154 mm carapace width (Williams, 1984), and common along southeastern U,S. Atlantic and Gulf of Mexico beaches (Gunter, 1950; Wass, 1955; Anderson et al., 1977; Leber, 1982), little is known of its life history, especially in the Gulf of Mexico. The portuninid genera Arenaeus Dana, Callinectes Stimpson, Cronius Stimp- son, and Portunus Weber are known to occur in the Gulf (Felder, 1973; Powers, 1977). The first zoeal stage of at least one species has been described for each genus except Cronius. For species from the Gulf, complete larval development in the laboratory is known for C. sapidus Rathbun, 1896; C. similis Williams, 1966; and P. spinicarpus (Stimpson, 1871) (see Costlow and Bookhout, 1959; Bookhout and Costlow, 1974; 1977). Partial descriptions from laboratory hatched larvae are available for zoeae I-III of P. gibbesii (Stimpson, 1859) (see Kurata, 1970) and for zoea I of P. depressifrons (Stimpson, 1859) (see Lebour, 1944), P. sayi (Gibbes, 1850) (see Lebour, 1944; Kurata, 1970), and P. spinimanus Latreille, J 8 J 9 (see Lebour, J 950). Sandifer (1972) provided a detailed description of a laboratory hatched zoea I of A. cribrarius. Two reports specifically mention the occurrence of A. cribrarius in the plankton. Goy (1976) reported zoeae I of A. cribrarius from plankton samples at two stations
lOl 102 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
DL
TL
cw
TL
Frontal View Dorsal View Zoea I Megalope Figure I. Schematic of portuninid zoea I and megalopa indicating: total length (TL); total spine length (TSL); rostral length (RL); dorsal spine length (DL); spine width (SW); carapace length (CL); length oftelson (LT); telson width (TW) telson fork length (FL); outer telson spines (0,1-3); inner telson spines (I, 1-3); and central arch of telson (CA).
in the mouth of Chesapeake Bay, in July, and Truesdale and Andryszak (1983) reported megalopae of A. cribrarius from two stations in the northern Gulf, east of the Mississippi River delta. On the other hand, Sandifer (1975) cautioned that Callinectes spp. larvae reported in plankton studies off the southeastern U.S. coast might be a mixture of not only species of Callinectes, but also of Portunus spp. and A. cribrarius. In the present study, we describe the complete larval (zoeae I-VIII and mega- lopa) development ofA. cribrarius and briefly describe crab stages 1-3. To facilitate identification of portuninid first zoeae from plankton samples, particularly Gulf samples, we compare zoea I of A. cribrarius with those of some other Gulf species (c. sapidus, C. similis, Portunus depressifrons, P. gibbesii, P. sayi, P. spinicarpus, and P. spinimanus) using our own and published descriptions. We also compare A. cribrarius zoeae II-VIII and the megalopa with published descriptions of cor- responding larvae for C. sapidus, C. similis, and P. spinicarpus. Collection of ovigerous A. cribrarius during this study allowed us to elaborate its northern Gulf spawning season. This paper is the first in a projected series describing larval development of portunids from the Gulf of Mexico, intended to aid researchers studying larval recruitment of the commercially important blue crab C. sapidus. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CR/BRARlUS 103
Table I. Duration and survival of larval stages of Arenaeus cribrarius at 25°C and 300/00salinity
Duration (days) No. moiling Stage Minimum X Mode Maximum Died in molt to next stage Zoea I 4 5.1 5 6 9 Zoea II 4 5.4 6 6 7 Zoea III 3 4.0 4 5 6 Zoea IV 4 4.3 4 6 6 Zoea V 3 3.5 3 5 6 Zoea VI 5 5.4 5 6 5 Zoea VII 3 4.5 6 4 Zoea VIII 2 3 3 4 4 Megalopa
MATERIALS AND METHODS
An ovigerous specimen of A. cribrarius was collected in the surf zone of Horn Island, Jackson County, Mississippi, 0.8 km east of Dog Keys Pass on the night of 28 April 1982. The eggs hatched during the night of 29 April 1982. Larvae were placed, one per compartment, into an 18-compart- mcnted polystyrene tray. Approximately 200 larvae were mass cultured in each of three IO-cm diameter glass finger bowls. Megalopae obtained in mass culture were separated into individual finger bowls. Tray and bowls were placed in a constant temperature unit at 25°C with a 12-h photoperiod. Aged scawater (300/00salinity), filtered through a I-Itm filter to which 50 mg per liter streptomycin sulfate and 40 mg per liter penicillin had been added, was changed daily in each compartment and bowl. Larvae were fed daily the following diet: zoeae I-III, rotifers (Brachionus plicatilis); zoeae IV-VI, a mixture of rotifers and frcshly hatched brine shrimp nauplii; zoeae VI-VIII, brinc shrimp nauplii only; megalopa and crabs, pieces of penaeid shrimp abdominal tissue. Exuviae, dead larvae, and a developmental series from the mass culture were initially preserved in 5% buffered formalin and later transfcrred to 70% ethanol. At least six specimens were measured and dissected for each stage, zoea through megalopa. Seven crab I specimens were measured, but only two specimens of crab 2, and one of crab 3. Ovigerous females of the following species were collected in Mississippi Sound or nearshore Gulf waters on the dates indicated: A. cribrarius, 12 August 1981; C. sapidus, I September 1982; C. similis, I August 1981; P. gibbesii. 20 August 1981; P. sayi. 12 August 1984; P. spinimanus, 14 October 1982; and P. spinicarpus, 14 October 1982. Zoea I larvae were subsequently obtained from laboratory or shipboard hatchings. At least five zoea I specimens of each species were examined and measured. Measurements ofzoeal and megalopal stages were adapted from Kurata (1975) and were made with an ocular micrometer using a dissection microscope as indicated in Figure I. Carapace width (CW) for crab stages was measured between lateral carapace spines. A developmental series of zoea I through crab 3 has been deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM 373829).
RESULTS OF THE REARING EXPERIMENT No prezoeae were observed; eight zoeal stages followed by a megalopa were observed among tray-reared specimens. In mass culture, a few specimens appeared to share characteristics of both zoeae VI and VII. Table I summarizes duration of instars for tray-reared larvae. Although no tray-reared larvae survived to mega- lopa, zoea VIII larvae died in molt to megalopa 34-40 days after hatching. In mass culture, viable megalopae were obtained in 30 days, and crab 1 specimens, 13 days later. Types of Setae. - Setae types recognized on the appendages of the zoeae and megalopa of A. cribrarius were similar to those described and figured by Bookhout and Costlow (1974; 1977) with three exceptions. We defined a sparsely plumose seta (Fig. 2D)-slender bearing scattered «20) setules along entire shaft or few (4-6) setules confined to proximal half of shaft; hooked serrate seta (Fig. 21)- longest and distalmost setae on dactylus of pereopod 5 of the megalopa; serrate 104 BULLETIN OF MARINE SCIENCE, VOL. 42, NO.1, 1988
A
B c o E F G
;--
H
K
Figure 2. Types of setae identified from Arenaeus cribrarius. A, Simple; B, Aesthetasc; C, Plumose; D, Sparsely plumose; E, Plumodenticulate; F, Cuspidate; G, Multidenticulate; H, Serrate; I, Hooked serrate; J, Modified hooked serrate; K, Heavy toothed serrate. seta (Fig. 2H)-similar to "long toothed serrate seta" (Bookhout and Costlow, 1977: 706, fig. 1D) or to "fine serrate seta" (Bookhout and Costlow, 1977: 706, fig. IE). Setae numbers and types occurring on the maxillular and maxillar endites of A. cribrarius larvae are listed in Tables 2 and 3, respectively. Setae types and numbers on other appendages are reported in the descriptions of stages (below). Pigmentation. -Cursory observations on pigmentation made from live specimens indicated chromatophore patterns similar to those described by Bookhout and Costlow (1977) for C. similis with some exceptions. We noted in the megalopa and crab I a distinct large black chromatophore on each eyestalk. This chro- matophore was visible in live animals and specimens preserved for several years. Additionally, the megalopa had numerous chromatophores, particularly over the ventral body, giving live and freshly preserved specimens a striking golden-brown STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARIUS 105
Table 2. Maxillule setation of Arenaeus cribrarius
Basal endite Coxal endite Stage Marginal Submarginal Marginal Submarginal Zoea I IPD,3MD IPD 4PD,2MD ZOCaII IPD,3MD 3PD 3PD,3MD Zoea III IPD,4MD,ISP 3PD 3-4PD,3MD Zoea IV IPD,4MD,ISP 3-4PD 3-4PD,3MD IPD Zoea V IPD,4MD,ISP 4-5PD 4PD,3MD IPD Zoea VI 1-2PD, 5MD, 1-2SP 5PD 3PD, 4MD, 1-2SP IPD Zoea VII 2PD, 5MD, 2-3SP 7PD 3PD, 4MD, 2-3SP 2PD Zoea VIII 3PD, 5MD, 3-4SP 9PD 3PD, 5MD, 3-4SP 2PD Mega]opa 3PD(Long), 9MD, 3- 9-IOPD 7-8PD,4SP(Long), 2PD 4PD(Short), 4-6SS 2SP(Short), 4-5SS
PD '=' plumodenticulate, MD :;;::multidenticulate, SP = sparsely plumose, SS = simple spinelike. hue. Crabs 1 and 2 had little or no body pigmentation, and crab 3 had a few scattered chromatophores on the carapace. Description of Developmental Stages.-Morphometrics for all zoeal, megalopa, and crab stages (1-3) are given in Table 4.
Zoea I
Carapace (Fig. 3A, B): Bearing elongate dorsal, rostra], and ]ateral spines, minute spinelike seta present on each side of dorsal spine base, posteroventral margin finely serrate. Eyes sessile. Antennule and antenna (Fig. 3C): Antennule conical, bearing 3 terminal aesthetascs, I simple elongate seta and I minute simple seta. Antenna approximately equal in length to rostral spine, consisting of elongate protopodite bearing 2 rows of short spines on distal half and short exopodite with I long and I short terminal seta; unchanged in general structure through zoea IV. Mandible (Fig. 3D): Asymmetrica], with strongest denticles on ventral edge, cutting ridges present on ventral and medial surfaces, no palp; unchanged in general structure through zoea VII. Maxi1lule (Fig. 3E): Endopodite 2-segmented, distal segment bearing 4 term ina] and 2 subterminal plumodenticulate setae, proximal segment with single media] sparsely plumose seta, pattern of setat ion unchanged through zoea VIII; basal endite with 4 marginal and I submarginal setae; coxal endite with 6 marginal setae. Types of setae on coxal endites of zoeae I-VIII and of the megalopa are given in Table 2. Maxilla (Fig. 3F): Scaphognathite with 4 plumose setae, posterior margin produced into slender plumose tip; endopodite unsegmented, with 2 pair of terminal and I subterminal pair of plumoden- ticulate setae, setation pattern unchanged through zoea VIII; basal endite bilobed, each lobe bearing I submarginal and 3 marginal setae; coxal endite bilobed, distal lobe with I submarginal and 2 marginal setae, proximal lobe with 3 marginal setae. Types of setae on basal and coxal endites ofzoeae I-VIII and of the megalopa are given in Table 3. Maxilliped I (Fig. 3G): Coxa with single lateral plumose seta; basis bearing 10 sparsely plumose setae clustered in proximal to distal groups of2, 2, 3 and 3; setation pattern of coxa and basis unchanged through zoea VI; endopodite 5-segmented, with proximal to distal setation pattern of 2, 2, 0, 2, 4+ (I subterminal) sparsely plumose setae, setation pattern unchanged through zoea IV; exopodite un- segmented, bearing 4 natatory setae. Maxilliped 2 (Fig. 3H): Coxa lacking setae; basis bearing 4 sparsely plumose setae; endopodite 3-segmented, distal margin of proximal 2 segments each with I sparsely plumose seta, distal segment with 5 sparsely plumose setae of different lengths; setation of coxa, basis and endopodite unchanged through zoea VIII; exopodite unsegmented, bearing 4 nata tory setae. Abdomen and tel son (Fig. 38, I, J): Abdomen 5-segmented, dorsolateral surfaces of segment 2 with blunt anteriorly pointing spine, segment 3 with lateral, ventrally pointing spines, segments 3-5 with serrate ]ateral projections, posterodorsal margins of segments 2-5 each bearing 2 short simple setae. Telson furcate, eaeh ramus bearing I strong and I minute lateral spine and I small dorsal spine, inner margin of each ramus bearing 3 large serrate spines, innermost of which armed with numerous stiff setules along medial margin. 106 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. 1,1988
Table 3. Maxilla setation of Arenaeus cribrarius
Basal endite Coxal endite Stage Marginal Submarginal Marginal Submarginal Zoea I Dist. IPD,2SP IPD 2SP (PD ProX. IPD,2SP IPD 3SP Zoea II Dist. IPD,2SP IPD 2SP IPD ProX. IPD,2SP IPD ISP 2SP Zoea III Dist. 1-2PD,2SP IPD IPD,2SP ProX. 2PD,2SP IPD 2S ISP Zoea IV Dist. 2PD,2SP (PD ISP IPD,2SP Prox. 2PD,2SP (PD 2SP (SP Zoea V Dist. 3PD,2SP IPD ISP IPD,2SP Prox. 3PD,2SP IPD 2SP (SP Zoea VI Dist. 3PD,2SP 1-2PD ISP IPD,2SP Prox. 3PD,2SP 1-2PD 3SP ISP Zoea VII Dist. 3-4PD,2SP 2PD ISP IPD, 2SP, IP Prox. 3-4PD,2SP 2PD 3SP* 2SP Zoea VIII Dist. 4-5PD,2SP 3PD IPD,ISP IPD, 2SP, IP Prox. 4-5PD, ISP 3PD 4-5SP 2SP Megalopa Dist. I0-12S P(Long), 2PD, 4-5SP IP ISP(Minute) ISP(Minute) Prox. 4PD,4-5SP 2PD, 3PD,4-5SP 3SP ISP(Minute) * One additional minute SP present in some specimens; PD = plumodenticulate, SP = sparsely plumose, P = plumose.
Zoea II
Carapace (Fig. 4A): Posterolateral margin smooth, each bearing I seta, anterior margin with ( medial seta, otherwise carapace as in zoea I. Eyes stalked. Antennule (Fig. 4B): As in zoea I except for a second long simple seta in some specimens. Maxillule (Fig. 4C): Plumose seta added below base of endopodite, present in all succeeding zoeal stages; basal endite with 4 marginal and 3 submarginal setae; coxal endite bearing 6 marginal setae. Maxilla (Fig. 4D): Scaphognathite bearing 8 plumose setae separated into anterior (5 setae) and posterior (3 setae) groups; setation of distal and proximal lobes of basal endite as in zoea I; distal lobe of coxal endite produced into pointed terminal process; bearing I submarginal and 2 marginal setae, proximal lobe with I submarginal and 2 marginal setae. Maxilliped I (Fig. 4E): Exopodite bearing 6 natatory setae. Maxilliped 2 (Fig. 4F): Exopodite bearing 6 nata tory setae. Abdomen and telson (Fig. 4A, G): Abdominal segments 3-5 with short acute lateral spines. Central arch of telson (Fig. I) bearing pair of small serrate spines. Abdomen and tel son otherwise as in zoea I.
Zoea III
Carapace (Fig. 5A): Posterolateral margins each bearing 3 setae, otherwise, carapace as in zoea II. Antennule (Fig. 5B): As in zoea II except second long seta rarely occurs. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CR1BRARlUS 107
'iii o N'" '-o
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-;; -;; - - ~ >- N", oj -oj oj oj oj oj oj .0 .0.0 - oj oj '"o '"o '"o '"o '"o '"o '"o r: ...... N N N N N N N u UU 108 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
c
>------~-----< A,B O.4mm C.G-J O.2mm D·F 0.1 mm
Figure 3, Zoea L A, Entire zoea (anterior view); B, Entire zoea (lateral view); C, Antennule and antenna; D, Mandible; E, Maxillule; F, Maxilla; G, Maxilliped I; H, Maxilliped 2; I, Abdomen (detail); J, Telson. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARIUS 109
A 0.4 mm B, E·G 0.2 mm C,D O.lmm
Figure 4. Zoea II. A, Entire zoea; B, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
Maxillule (Fig. 5C): Basal endite with 6 marginal and 3 submarginal setae; coxal endite with 6-7 marginal setae. Maxilla (Fig. 5D): Scaphognathite bearing 12-14 plumose setae separated into anterior (8-9 setae) and posterior (4-5 setae) group distal lobe of basal endite bearing I submarginal and 3 marginal 110 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
A D.7mm B, E·G O.2mm C,O O.\mm
Figure 5. Zoea III. A, Entire zoea; B, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
setae, proximal lobe with I submarginal and 4 marginal setae; distal lobe of coxal endite with 3 submarginal setae, terminal margin produced into pointed process, setation of proximal lobe as in zoea II. Maxilliped I (Fig. 5E): Exopodite bearing 8 natatory setae. Maxilliped 2 (Fig. 5F): Exopodite bearing 8 natatory setae. Abdomen and telson (Fig. 5A, G); Abdomen 6-segmented, 1st abdominal segment with pair of dorsal setae, lateral spines of segment 3 overlapping one-half length of segment 4, lateral spines of segments 4 and 5 much shorter than those of segment 3. Telson as in zoea II. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRfBRARfUS III
A O.8mm B·O O.2mm E-G 0.25 mm
Figure 6. Zoea IV. A, Entire zoea; B, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
Zoea IV
Carapace (Fig. 6A): Posterolateral margins each bearing 5 setae, otherwise, carapace as in zoea III. Antennule (Fig. 6B): As in zoe a III. Maxillule (Fig. 6C): Basal endite bearing 6 marginal and 3-4 submarginal setae; coxal endite with I submarginal and 6-7 marginal setae. 112 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
Maxilla (Fig. 6D): Scaphognathite bearing 16-19 plumose setae; distal and proximal lobes of basal endite each with I submarginal and 4 marginal setae; distal lobe of coxal endite with I marginal and 3 submarginal setae, setation of proximal lobe as in zoe a III. Maxilliped I (Fig. 6E): Exopodite bearing 9-10 natatory setae. Maxilliped 2 (Fig. 6F): Exopodite bearing 9-10 natatory setae. Third maxilliped and pereopods (Fig. 6A): Present as small buds beneath carapace. Abdomen and telson (Fig. 6A, G): Lateral spines of abdominal segment 3 overlapping slightly more than one-halflength of segment 4, posterior margin of segment 6 with weakly developed lateral spines. Telson armature as in zoea III.
Zoea V
Carapace (Fig. 7A): Posterolateral margins each bearing 7-9 setae, rostral spine slightly longer than antennal protopodite. Antennule and antenna (Fig. 7B): Antennule as in zoea IV. Antenna with weakly developed en- dopodite bud distal to insertion of exopodite. Maxillule (Fig. 7C): Basal endite bearing 6 marginal and 4-5 submarginal setae; coxal endite with I submarginal and 7 marginal setae. Maxilla (Fig. 7D): Scaphognathite bearing 21-24 plumose setae; proximal and distal lobes of basal endite each with I submarginal and 5 marginal setae, setation of proximal and distal lobes of coxal endite as in zoea IV. Maxilliped I (Fig. 7E): Proximal to distal setation patternofendopodite 2, 2, 1,2,4+ (2 subterminal), remaining unchanged through zoea VIII; exopodite bearing 10-11 natatory setae. Maxilliped 2 (Fig. 7F): Exopodite bearing 11-12 natatory setae. Third maxi IIipeds and pereopods (Fig. 7A): Extending below carapace, undifferentiated. Abdomen and telson (Fig. 7A, G): As in zoea IV.
Zoea VI
Carapace (Fig. 8A): Posterolateral margins each bearing 9-11 setae, rostral spine 1.25 times length of antennal protopodite. Antennule and antenna (Fig. 8B): Antennule with terminal group of 3-4 aesthetascs, 1-2 long simple setae and I minute simple seta, and subterminal group of I aesthetasc and 1-2 long simple setae. Endopodite bud of antenna reaching to distal margin of antennule. Maxillule (Fig. 8C): Basal endite with 7-9 marginal and 5 submarginal setae; coxal endite bearing I submarginal and 8-9 marginal setae. Maxilla (Fig. 8D): Scaphognathite bearing 24-27 plumose setae; proximal and distal lobes of basal endite bearing 1-2 submarginal and 5 marginal setae; distal lobe of coxal endite with I marginal and 3 submarginal setae, proximal lobe bearing 3 marginal and I submarginal setae. Maxilliped I (Fig. 8E): Exopoditc bearing 11-12 natatory setae. Maxillipcd 2 (Fig. 8F): Exopodite bearing 12-14 natatory setae. Third maxillipeds and pereopods (Fig. 8A): Buds lengthened, still undifferentiated. Abdomen and telson (Fig. 8A, G): Pleopod buds present as slight swellings on posteroventral margin of abdominal segments 3-5; lateral spines of segment 3 nearly reaching posterior margin of segment 4, lateral spines of segments 4 and 5 about half length of succeeding segments. Telson as in zoea V.
Zoea VII
Carapace (Fig. 9A): Posterolateral margins each bearing 14-15 setae; rostral spine about 1.5 times length of antennal protopodite. Antennule and antenna (Fig. 9B): Antennule with terminal group of 3-4 aesthetascs, 1-2 long simple setae and I minute seta, distal subterminal group of 3 aesthetascs and 3 long simple setae, and in some specimens a second proximal subterminal group of 2 aesthetascs; precursor of inner ramus a slight swelling proximal to insertions of subterminal aesthetasc groups. Antennal endopodite bud extending beyond distal margin of antennule. Maxillule (Fig. 9C): Basal endite with 9-10 marginal and 7 submarginal setae, coxal endite bearing 9-10 marginal and 2 submarginal setae. Maxilla (Fig. 9D): Scaphognathite bearing 30--34 plumose setae; proximal and distal lobes of basal endite each with 5-6 marginal and 1-2 submarginal setae; distal lobe of coxal endite with I marginal and 4 submarginal setae, proximal lobe with 2 submarginal, 3 long and rarely I minute marginal setae. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARfUS 113
A 1.2 mm B·D O.13mm E·G 0.4 mm
Figure 7. Zoea V. A, Entire zoea; B, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
Maxilliped I (Fig. 9E): Coxa bearing 2 sparsely plumose setae on posterolateral lobe, epipodite bud present on anterior margin; exopodite bearing 13-14 natatory setae. Maxilliped 2 (Fig. 9F): Exopodite bearing 14-16 natatory setae. Third maxilliped and pereopods (Fig. 9A): Beginning to differentiate, first pereopod bud distinctly bifurcate. Abdomen and telson (Fig. 9G): Pleopod buds well developed, particularly on abdominal segments 114 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
-f'I
A 1.1 mm 8, E·G 0.4 mm C.D 0.19 mm
F
Figure 8. Zoea VI. A, Entire zoea; B, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
2-5, uniramous; lateral spines on segments 3 and 4 nearly extending to posterior margin of succeeding segments, lateral spines of segment 5 three-fourths length of segment 6; segment I with 3 dorsal setae. Telson with 3 small spines on central arch, otherwise, as in zoea VI.
Zoea VIII
Carapace (Fig. lOA): Posterolateral margins each bearing 17-19 setae; rostral spine 1.8 times length of antennal protopodite. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARIUS 115
A 1.1mm B. E·G O.4mm G C,D O.2mm
Figure 9. Zoea VII. A, Entire zoea; 8, Antennule and antenna; C, Maxillule; D, Maxilla; E, Maxilliped I; F, Maxilliped 2; G, Telson.
Antennule and antenna (Fig. lOB): Antennule with terminal group of 4 aesthetascs, I long simple seta and I minute seta, and 2 subterminal groups, each with 5 aesthetascs and I long simple seta; inner ramus a well developed bud. Antennal endopodite bud extending three-fourths length of pro- topodite. Mandible (Fig. IDC): Small unsegmented palp present, otherwise, as in previous stages. 116 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
A 1.1mm B 0.4 mm t·e O.2mm F·I 0.6mm
Figure 10. Zoea VIII. A, Entire zoea; B, Antennule and antenna; C, Mandible; D, Maxillule; E, Maxilla; F, Maxilliped I; G, Maxilliped 2; H, Pereopod I; I, Telson (ventral view).
Maxillule (Fig. IOD): Basal endite with 11-12 marginal and 9 submarginal setae; coxal endite with 11-12 marginal and 2 submarginal setae; 2 plumose setae present below base of endopodite. Maxilla (Fig. IOE): Scaphognathite bearing 40-43 plumose setae; distal lobe of basal endite bearing 6-7 marginal and 3 submarginal setae, proximal lobe with 5-6 marginal and 3 submarginal setae; STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAE US CR/BRARIUS 117 coxal endite bearing 2 marginal and 4 submarginal setae on distal lobe, proximal lobe with 4-5 marginal and 2 submarginal setae. Maxilliped I (Fig. IOF): Coxa bearing 3 plumose setae on posterior lobe, epipodite bud large, extending ventrally beyond anterior margin of basal segment; exopodite bearing 15-17 natatory setae. Maxilliped 2 (Fig. lOG): Exopodite bearing 17-18 natatory setae. Third maxilliped and pereopods (Fig. IDA, H): All buds clearly differentiated; pereopod I well developed, chelate, completely segmented in most specimens, other buds incompletely segmented. Abdomen and telson (Fig. 101): Pleopod buds on abdominal segments 2-5 longer than in zoea VII, biramous; segment I with 4 dorsal setae. Telson as in zoea VII.
Megalopa
Carapace and pereopods (Fig. IIA, D, E): Carapace rectangular, lacking dorsal and lateral spines; rostrum 0.8 times length of antenna; strong pair of spines extending from 7th sternal segment posteriorly to anterior margin of 3rd abdominal segment. Eyestalks each with a distinct pigment spot on dorsal surface. Pereopod I chelate, 5-segmented, cutting edge of propodus slightly longer than dactylus, bearing 2 large and 2 small teeth, carpus with weak dorsal and strong medial spine, ischium with hooked spine; pereopod 2 with spine on ventral side of basis, otherwise, pereopods 2-4 similar; dactylus of pereopod 5 paddlelike, distal to proximal setation pattern of I long hooked serrate seta, 2 long modified hooked serrate setae, 7 short simple hooked setae and several scattered small simple setae. Antennule (Fig. liB): Basal segment bulbous, bearing I sparsely plumose seta on lateral margin; 2nd segment slightly longer than 3rd, with I simple and 6 plumose setae on distal margin; 3rd segment bulbous, bearing 2 plumose setae near base of inner ramus and I sparsely plumose seta distally; inner ramus unsegmented, bearing I short subterminal and 5 long terminal setae; outer ramus of 5 segments: segment I without setae; segment 2 with 13-14 aesthetascs; segment 3 bearing 11-12 aesthetascs and I simple dorsal seta; segment 4 with 8 aesthetascs, I long simple dorsal, and I small lateral simple seta; segment 5 bearing proximal group of 5 aesthetascs, I subterminal simple and I terminal plumose seta. Antenna (Fig. II C): Consisting of II segments, distal 8 segments 1.3 times length of proximal 3 segments, setation pattern as shown. Mandible (Fig. 12A): Cutting surface with distinct medial tooth; palp of 2 segments, distal segment bearing 4 sparsely plumose setae, 3 multidenticulate setae, and 8-9 plumodenticulate setae. Maxillule (Fig. 12B): Endopodite appearing segmented in some specimens, weakly calcified, bearing 2 proximal pairs of sparsely plumose setae and 2 short simple terminal setae; basal endite bearing 19-22 marginal and 9-10 submarginal setae; coxal endite with 17-19 marginal and 2 submarginal setae. Maxilla (Fig. 12C): Scaphognathite bearing 72-76 plumose marginal setae and 13-14 simple sub- marginal setae; endopod unsegmented, weakly calcified, bearing 5 setae near base; basal endite bearing 11-13 marginal setae, and 3 submarginal setae on distal lobe, proximal lobe with 8-9 marginal and 3 submarginal setae; coxal endite with I submarginal and 4-5 marginal setae on distal lobe, proximal lobe bearing 7-8 marginal and 3 submarginal setae. Maxilliped I (Fig. 12D): Endopodite unsegmented, broad distal margin bearing 5 simple setae; exopodite 2-segmented, with 4 small plumose setae on proximal segment, distal segment with I short and 3 long sparsely plumose terminal setae; basal endite bearing 5 multidenticulate and 32-34 plu- modenticulate setae on or near margin and row of 7-8 sparsely plumose setae submarginally; coxal endite with 2 marginal multidenticulate setae and 19-20 plumodenticulate setae: 9 marginal, 10-11 submarginal; epipodite elongate, with row of6 thick marginal and 4 slender submarginal simple setae on proximal one-third, distal two-thirds with 14-16 long simple setae. Maxilliped 2 (Fig. 13A): Basis bearing I short submarginal and 4 long marginal sparsely plumose setae; endopodite 5-segmented, segment I (proximal segment) with 2 submarginal sparsely plumose setae and I long marginal simple seta, segment 2 bearing 3 simple setae and 3 submarginal sparsely plumose setae, distal margin of segment 3 with 2 simple setae and I long and I short plumodenticulate seta, inflated 4th segment bearing I simple and 5 plumodenticulate marginal setae and 4-5 submarginal sparsely plumose setae; segment 5 with 8 strong cuspidate setae and in some specimens I minute simple seta on distal margin, and I simple and I sparsely plumose submarginal seta; exopodite of 2 segments, proximal segment with 2 simple marginal setae, distal segment with 3 long plumose and I shorter sparsely plumose terminal seta. Maxilliped 3 (Fig. 13B): Endpodite of 5 segments; segment I (proximal segment) bearing 32-33 setae: 9 small cuspidate, 3 serrate, 9 multidenticulate, 6 plumodenticulate, 4-5 simple and 4 sparsely plumose; segment 2 bearing 17-18 setae: 3 simple, 5-6 sparsely plumose, 4 plumodenticulate and 5 multidenticulate; segment 3 with 16 setae: 3 simple, 6 serrate, 6 plumodenticulate and I multiden- ticulate; segment 4 bearing 16-17 serrate setae of several lengths, segment 5 with 7 heavy toothed 118 BULLETIN OF MARINE SCIENCE, VOL. 42, NO.1, 1988
E
A, E 1.1mm B O.2mm C O.4mm o O.5mm
Figure 11. Megalopa. A, Entire megalopa (dorsal view); B, Antennule; C, Antenna; D, Chela (distal tip); E, Thoracic sternum (left ventral view), serrate setae and 9-10 serrate setae of several lengths; exopod of 2 segments, proximal segment lacking setae, distal segment bearing 5-6 terminal plumose setae; epipod elongate bearing 17-19 long simple setae distally and group of 5 sparsely plumose setae proximally. Abdomen and pleopods (Figs. llA, 13C): Abdomen of 6 segments and telson, 5th segment with strong lateral spines extending beyond posterior margin of 6th abdominal segment; telson with slightly convex distal border, lacking spines or setae. Pleopods present on abdominal segments 2-6; exopods STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CR/BRARIUS 119
Figure 12. Megalopa. A, Mandible; B, Maxillule; C, Maxilla; 0, Maxilliped I. of pleopods 1-4 bearing 27-28, 27, 25-26, and 20-22 plumose setae, respectively; endopods of pleopods 1-4, bearing 4-5,4, 3-4 hooked spines, respectively; pleopod 5 lacking endopod, bearing I simple seta on basal segment and 12-13 plumose setae on exopod.
Juvenile Crabs
Crab 1-3 (Fig. 130): Frontal margin of carapace with inner orbital teeth produced anteriorly, subequal in length to bifid medial process. First crab with 8 blunt anterolateral teeth which become 120 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988
A,B O.2mm C O.4mm o 2.8mm Figure 13. Megalopa. A, Maxilliped 2; B, Maxilliped 3; C, Pleopod 2; D, Carapace (crab 1-3) and chela (crab 3).
more acute in crabs 2 and 3, crab 3 with few scattered pigment spots on carapace; eyestalks of first crab with distinct dorsal pigment spot, absent in crabs 2 and 3; carpus of cheliped with small dor- somedial and larger lateral spine, small dorsal spine on proximal margin of propodus present in crabs 2 and 3.
DISCUSSION Spawning Season oj Arenaeus cribrarius. -Occurrences of ovigerous A. cribrarius in the northern Gulf of Mexico have been unreported, and information on its STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRAR/US 121
e s
.5 00 OJ ell •.... =ell o .0~ OJ =S OJ•... ::3 ~ell OJ .§. .,...0-, ""- o 00\0 ""
<'I,..... <'I,..... '0 '=!~ '=!~ OJ ~ o. o. ~C. o +1- i +19 ..c:: ",,60.- o-,o-,-.b"" .! ..e NOO~- o'=!""e . ·0 . Qj '- . ~rJ) 00_0 .0 os -_0 8 -1---1-- ·K 000 OJ o o o o \0- ~ z z z z 00 '-o :;'- o 0 I.? o 0'0 •.. E +1 +1 t I':: OJ 0-, <'1::3 o OJ ..c:: 00 _t"f"'l U •.... t: .0'" o ci t;.ci ~ o ~ I':: OJ E o ell '-o ~ OJ o N '-o '"•... B u •...~ ..c::~ u '0 B u OJ Qj ell '-o I':: o ·C'" ~c. S o u 122 BULLETIN OF MARINE SCIENCE, VOL. 42, NO.1, 1988 B c o L--- H G Figure 14. Antennae of Portuninae first zoea. A, Arenaeus cribrarius; B, Callinectes sapidus; C, Callinectes similis; D, Portunus depressifrons (redrawn from Lebour, 1944); E, Portunus gibbesii; F, Portunus sayi; G, Portunus spinicarpus; H, Portunus spinimanus. spawning times is from Venezuela, Brazil, and the U.S. east coast (Williams, 1984). Ovigerous specimens producing larvae used in this study were taken in late April and mid-August. During spring through summer, we have made many observations of ovigerous females, particularly at night on Mississippi, Alabama, and northwest Florida Gulfbeaches. We have also trawled an ovigerous specimen in mid-October in 11 m depth, 1.4 km south of Gulf Shores, Alabama. Therefore, the spawning period of A. cribrarius in the Gulfis at least 2-3 months longer than that reported in South Carolina (mid-June through mid-September) by Anderson et al., 1977. Number of Larval Stages in Western Atlantic Portuninae. -Marked variability exists in number of zoeal stages among and often within species of Portuninae (Bookhout and Costlow, 1974; Kurata, 1975; Rice and Ingle, 1975; Fielder and Greenwood, 1979). In the western Atlantic, C. sapidus and C. similis have six to eight zoeal stages, and P. spinicarpus has seven or eight, but usually all three species have seven zoeal stages (Bookhout and Costlow, 1974; 1977). Zoea VIII larvae have been reported from plankton in U.S. Atlantic coastal waters for C. sapidus (Nichols and Keney, 1963; McConaugha et al., 1983) and in the Gulf of Mexico for Callinectes spp. (Truesdale and Andryszak, 1983). Plankton collections (Gulf of Mexico) yielded no zoea VIII of Portunus spp. (Truesdale and Andryszak, 1983). Data from the present study indicate that eight zoeal stages are usual for A. cribrarius in laboratory culture. However, a few specimens in mass culture appeared to have combined characteristics of zoeae VI and VII. Combination of morphological characters from two late zoeal stages into one stage was the most common variability in molting reported by Costlow (1965) for laboratory reared C. sapidus. Combining ofzoeal stages VI and VII in A. cribrarius may reduce the number of pre-megalopa instars to seven. Comparisons of First Zoea of Shallow-water Gulf of Mexico Portuninae.-San- difer's (1972) description of zoea I of A. cribrarius from South Carolina agrees closely with ours; although, our descriptions of appendage setation and illustra- tions are more detailed. The only major discrepancy between Sandifer's (1972) STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARlUS 123 A c o F H Figure 15. Telsons of Portuninae first zoea. A, Arenaeus cribrarius; B, Callinectes sapidus; C, Cal- lillectes simi/is; D, Portunus depressifrons (redrawn from Lebour, 1944); E, Portunus gibbesii; F, Portunus sayi; G, Portunus spinicarpus; H, Portullus spinimanus. description and ours is that Sandifer reported four terminal antennular aesthetascs and no setae, contrasted with our three aesthetascs and two setae. Sandifer (1972) also described the posterior lateral projections on abdominal segments 3-5 as "bifid," but the projections, at least on segment 5 of our specimens, are clearly serrate (Fig. 3). We noted our zoea I specimens of A. cribrarius from April hatched eggs were larger (e.g., TL, RL, DL) than those from August (Tables 4 and 5). Measurements (TSL and DL) of a July hatched specimen taken from Sandifer's illustration (1972: 107, fig. 31) are almost identical to corresponding (average) measurements of our specimens from August (Table 5). Stuck and Perry (1982) reported that zoeae I-III of C. sapidus from the Gulf of Mexico hatched in April were significantly larger (e.g., TL, RL, DL) than those hatched in August. To minimize seasonal morphometric differences in our com- parisons ofportuninid zoeae I, we used only specimens from mid-August through mid-October hatches. Unfortunately, we had no material of P. depressifrons and relied on the few notes and illustrations of Lebour (1944). The species listed in Table 5 include most of the species ofPortuninae routinely encountered in shallow waters of the northern Gulf of Mexico (Felder, 1973; Powers, 1977). A combination of a number of the gross anatomical characters in Table 5 will allow routine separation of zoeae I of the species. Figures 14 and 15 ofzoeae I antennae and telsons, respectively, will aid in separation of species. All illustrations are drawn to the same scale from preserved larvae or exuviae, but zoea I structures of P. depressifrons have been proportionately enlarged from Lebour (1944, fig. 2). All zoeae I in Table 5 can be divided into two groups by 124 BULLETIN OF MARINE SCIENCE, VOL. 42, NO. I, 1988 00 00\ lI'l N * O\\O~\O -" \D \00<:1'- co NfC""lN~ "'<:1''''\0 "';OOO" 0'1-0\0 OONlI'l -anf'f"'l\O \D\O<:I'r- "';000'" "';000 -~•.. STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CRIBRARlUS 125 •....•. !l-.'" p.. ,,0~~ M ,,-:: Cl \0 :58 v ,,; E;- !log M Ii.' 0 VJ 0 ~'" a-. N'" N ~~ I ' N' 1:",,0 O~:;;O a -0 ,0 0 O~~O~ ~' o..;li ZddZ o- N- N Zc5c5Zv -0- g N '" '" •... ~ p.. M ~ \0 ,~~ 6 :'::::0 v EU N '!;;'tI o Ii." ..; VJ lifJ 00 00 NvO\O !'l'"I • -~oooo :; r"\Ovt"-- N 0 a •....0 0 -:~V:~E-<. ;li "":ddd - \0 !'l.a-. M !'lOOOv N-- "". g '" ~r=: ",,,, p.. !l:~. M ls.g 0' \0 afi a v N ~gu Ii.' ~"''g v ~ .~~~ "'0000 000\00 :::::«1 ::J •....vv •.... 00 N ~v:' p.. M 6 00 v •....I 00 ~~ vOv\O a o M"'\OV - 00 '" IT'l 00 I J, 0· I -:~~~E-< J "";ddd - a-. -'" a-. !'lOO-M --- "0... ;:l .5 j;; o U 126 BULLETIN OF MARINE SCIENCE, VOL. 42, NO.1. 1988 .•. r- a- tj-. 0.. 0.. e-~ M .,., \0 .§~ 0" Vl 0 '~8 "<1" N "<1" tj1! o Ii." 0 rl:l <'I .,.,a: ,," M\O "<1" M ••.•• I " <'I" ~g"'- \00 .0 o~ieo " ~ 60" M "<1" •..;i <'1\0 <'1- - <'I z....;oz~ <'10- M ••.•• ~ r- r- ~ 0.. 0.. ~. M "<1" .Q 0" \0 0 ~~ "<1" .,., e;U N ';::::"0 Ii." rn 0 00 a: .0 <'I N\O t..l" '" N' "<1"O\OlI) ;; I • MQ <'I "':C!~-;E-<' .;-;- ..,,0 <'I .•. 0 <'I.." N_"- .•. N-O-v N-- <'I \0 ~ '" o.-f"-. ",r- ~~ 0.. 0.. ~~;t M M \0 '-§o~0 ;;0 0 0" "<1" lI) N Vl ~g8 M Ii.' t:)Q:I'C a: ..: 0 "'00 ;:::;'" ~ \0 N" lI"'itn\OO ~;~ 60 "0 ":~or:~~ N lI) 0" r3 ~ 0 NlI) N- M .Qii - <'1000"<1" <'1\0 ;;;8 - 8", 0.. "<1" tj 0" 'i: " 0.. ~'O M "<1" 0 ~~ 0" \0 •....Ii.' "<1" I "'- N" Vl I ~& 0\ \0 ~:: "<1"Ii.' .;; •.... "0. N\O N . N M ~ -- NO NO\r--oot; -.: I " -I I I I -0 ~-:~~I -N ~~ .\.'1 N N\O N- N N-O-M N \0 '"0 ~'" '":l ",:a s:: .5 •..• s:: .g ..c::_'" E .-•..• < u s:: 0 '" ~u ~~ ..c:: .;.:; 0. 0 o.< >< rnlJ:l rJ} •....• rn'" 5= \0 0" C rJ} \0 rn \0 •.... "!"!~"lf-<'" 0 0\ '" " ,..,- ""-O-v rJ} ,.., rn'" \0 O\vonoo " - v ~O:~"lf-< - ,..,oo-v 0.. '?on .g 0" ~""~'" rJ} on :ga N N V 6 ci..' "- ..!. 00 (/) ,.l, ~& rn,.., •....I on " ~ - (/)" 1::"c. •.... V " V \0 ,:: ,..,0 on N -.: N \0 00 on ~n I v,..,"'- N ("C""l- V) I' ,.., ~r;~o:~ \0 ,..,6'1•.... J ,.., 6 N f"')---f"') v---"¢' NN "Cl •..'" '":s :.a'" .5 c:: C <1)-'" o ••• C II ..••... .. !l-:." ~ l:-~ :a ,,~,,0 II 0 1;-58 OJ !log c ,,~,," .~ l:: ~ ,,0 .D" o..;li ;;l 0 .g II '" ] .~ •... .!l ~ II 'i ~ I-< 0 .~-a '" l:i '::::0 .,..el ~ .~"O 0 "U Ii,;' U; 00 " :; n 0 .,.. •.... 0 ova..Cl .,.. Z ~ N .g ."00 ~ ~~ ~ ",,,, ." !l-.-' .,..~ ..•;j ~g~ U~ ~;li~ ~g8 .,..el tii tp:Q-o B co .5~~ M'" •....Ii; :::::::(13"5 ~" 0~o I - 0 ,g;li MCl M il MOO ' N NN ('I'j"'N"' N - N •.... ,.., -- .N *•....*N M • o -: 00 ("'.1"- .•. .,.., f'f") V)f'f")-\O N *•.... MN ~. ~. ~ N o N ~. 6 N 00 ~. N I til N I 0\ i:: N i:: V ,.., 0\ 0 ~ M ttl I V 0 .:.:ttl o V 0;9 ..c V "0 ttl 0"0 0..0 00.. "0 0 !:: >< UJUJ STUCK AND TRUESDALE: LARVAL DEVELOPMENT OF ARENAEUS CR1BRARlUS 131 Differences among megalopae (Table 7) are more obvious than those among zoeae (Table 6). The larger size (CW, CL) ofmegalopae of A. cribrarius has proven reliable in separating them from C. sapidus, C. similis, and Portunus spp. in Gulf plankton material (Stuck, unpublished). Additionally, a large chromatophore on each eyestalk of the megalopa of A. cribrarius separates it from megalopae of C. sapidus, C. similis, and P. spinicarpus, as described by Costlow and Bookhout (1959) and Bookhout and Costlow (1974; 1977). This character was also reliable when megalopae of A. cribrarius were compared to those of C. sapidus and C. similis from plankton samples taken in the Gulf of Mexico (Stuck, unpublished). Megalopae of A. cribrarius and P. spinicarpus have spines on the inner margin of pereopod 1 and basis of pereopod 2; these spines are absent in C. sapidus and C. similis (Table 7). All four megalopae (Table 7) can be separated using several single characters. The most useful of these include number of hooked setae on the pereopod 5 dactylus, number of endopod hooks and exopod setae on pleopods 1-5, setation ofthe scaphognathite, setation of the maxillar basal and coxal endites, and setation of maxilliped 3 epipodite (Table 7). Other than those of A. cribrarius (present study), the only Gulf portuninid for which crabs 1 and 2 have been illustrated and partially described is C. sapidus (Kurata, 1970; Stuck and Perry, 1982). The most striking difference between crabs 1 and 2 of A. cribrarius and those of C. sapidus is the much larger size (CW) of specimens of A. cribrarius. Carapace widths of crabs 1 and 2 of C. sapidus range 1.99-3.08 mm for crab I and 2.58-3.91 mm for crab 2 (Kurata, 1970; Stuck and Perry, 1982). Carapace width of crabs 1 and 2 of A. cribrarius ranged 4.35-4.58 mm for crab 1 and 6.70-7.00 mm for crab 2 (Table 2). The frontal carapace margin of crabs 1 and 2 of C. sapidus is slightly convex and bilobed, but without interorbital teeth (Kurata, 1970; Stuck and peJ;TY,1982). In crabs I and 2 of A. cribrarius, the frontal carapace margin has anteriorly projecting inner orbital teeth and a bifid medial process (Fig. 7D). ACKNOWLEDGMENTS We thank R. Heard for assistance in collecting ovigerous specimens. We also thank R. Heard and R. Overstreet for constructive criticism of an earlier draft of this manuscript and L. Laird for assistance in preparation of illustrations. We gratefully acknowledge C. Dickens for typing the manuscript. This research was supported in part by Gulf States Marine Fisheries Commission under contract number 000-0 II and United States Department of Agriculture contract number 85-CRSR-22538. LITERATURE CITED Anderson, W. D., Jr., J. K. Dias, R. K. Dias, D. M. Cupka and N. A. Chamberlain. 1977. The macrofauna of the surfzone off Folly Beach, South Carolina. U.S. Dept. Commerce, NOAA Tech. Rept. NMFS SSRF-704. 23 pp. Bookhout, C. G. and J. D. Costlow, Jr. 1974. Larval development of Portunus spinicarpus reared in the laboratory. Bull. Mar. Sci. 24: 20-51. -- and --. 1977. Larval development of Callinectes simi/is reared in the laboratory. Bull. Mar. Sci. 27: 704-728. Costlow, J. D., Jr. 1965. Variability in larval stages of the blue crab, Callinectes sapidus. BioI. Bull. 128: 58-66. -- and C. G. Bookhout. 1959. The larval development of Callinectes sapidus Rathbun reared in the laboratory. BioI. Bull. 116: 373-396. Felder, D. L. 1973. An annotated key to crabs and lobsters (Decapoda, Reptantia) from coastal waters of the northwestern Gulf of Mexico. Louisiana St. Univ. Center for Wetland Res. Publ., LSU-SG-73-02. Baton Rouge, Louisiana. 103 pp. Fielder, D. R. and J. G. Greenwood. 1979. Larval development of the swimming crab Tha/amita danae Stimpson, 1858 (Decapoda, Portunidae), reared in the laboratory. Proc. R. Soc. Queens!. 90: 13-20. Goy, J. W. 1976. Seasonal distribution and the retention of some decapod crustacean larvae within 132 BULLETINOFMARINESCIENCE,VOL.42, NO. 1,1988 the Chesapeake Bay, Virginia. Master's Thesis, Old Dominion University, Norfolk, Virginia. 334 pp. Greenwood, J. G. and D. R. Fielder. 1979. A comparative study of the first and final zoeal stages of four species of Thalamita (Crustacea: Portunidae). Micronesica 15: 309-314. Gunter, G. 1950. Seasonal population changes and distributions as related to salinity, of certain invertebrates of the Texas coast including the commercial shrimp. Publ. Inst. Mar. Sci. 1(2): 7-51. Juanico, M. 1978. Ampliacion de la distribucion geografica de tres especies de Brachyura (Crustacea Decapoda) pura aguas uruguayas. Iheringia. Ser. Zool., Porto Alegre (51): 45-46. Kurata, H. 1970. Studies on the life histories of decapod Crustacea of Georgia: Part III. Larvae of decapod Crustacea of Georgia. Final Rept. Univ. Georgia Mar. Inst., Sapelo Island, Georgia. 274 pp. --. 1975. Larvae of decapod Brachyura of Arasaki Sagami Bay- V. The swimming crabs of the subfamily Portuninae. Bull. Nansei Reg. Fish. Res. Lab. 8: 39-65. Leber, K. M. 1982. Seasonality of macro invertebrates on a temperate high wave energy sandy beach. Bull. Mar. Sci. 32: 86-98. Lebour, M. V. 1944. Larval crabs from Bermuda. Zoologica 29, Part 3 (10-15): 113-128. ---. 1950. Notes on some larval decapods (Crustacea) from Bermuda. Proc. Zool. Soc. Lond. 120: 369-379. McConaugha, J. R., D. F. Johnson, A. J. Provenzano and R. C. Maris. 1983. Seasonal distribution of larvae of Calfinectes sapidus (Crustacea: Decapoda) in the waters adjacent to Chesapeake Bay. J. Crust. BioI. 3: 582-591. Nichols, P. R. and P. M. Keney. 1963. Crab larvae (Callinectes), in plankton collections from cruises of the M/V Theodore N. Gill, south Atlantic Coast of the United States, 1953-54. U.S. Fish Wildl. Servo Spec. Sci. Rept. Fish. 448 pp. Powers, L. W. 1977. A catalogue and bibliography to the crabs (Brachyura) of the Gulf of Mexico. Contrib. Mar. Sci. Suppl. to Vol. 20. 190 pp. Rice, A. L. and R. W. Ingle. 1975. A comparative study of the larval morphology of the British portunid crabs Macropipus puber (L.) and M. holsatus (Fabricius), with a discussion of generic and sub-familial larval characters within the Portunidae. Bull. British Mus. Nat. Hist. (Zool.) 28: 123-151. Sandifer, P. A. 1972. Morpho]ogy and ecology of Chesapeake Bay decapod crustacean larvae. Ph.D. Dissertation, University of Virginia. 532 pp. ---. ]975. The role of pelagic larvae in recruitment to the populations of adult decapod crustaceans in the York River estuary and adjacent lower Chesapeake Bay, Virginia. Estaurine Coast. Mar. Sci. 3: 269-279. Stuck, K. C. and H. M. Perry. 1982. Morpho]ogical characteristics of blue crab larvae, Callinectes sapidus Rathbun, from the northern Gulf of Mexico. Completion Rept., Gu]f States Mar. Fish. Comm. Contract Number 000-011. 53 pp. Truesdale, F. M. and B. L. Andryszak. 1983. Occurrence and distribution of reptant decapod crus- tacean larvae in the neritic Louisiana waters: July 1976. Contrib. Mar. Sci. 26: 37-53. Wass, M. L. 1955. The decapod crustaceans of Alligator Harbor and adjacent inshore areas of northwestern Florida. Quart. J. F]a. Acad. Sci. ]8(3): 129-176. Williams, A. B. 1984. Shrimp, lobsters, and crabs of the Atlantic coast of the eastern United States, Maine to Florida. Smithsonian Institution Press, Washington, D. C. 550 pp. DATEACCEPTED: February 17, 1987. ADDRESSES:(K.C.S.) Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564; (F.M. T.) School of Forestry, Wildlife and Fisheries, and Louisiana Agricultural Experiment Station, Louisiana State University, Baton Rouge, Louisiana 70803.