FIRST ZOEAL STAGE OF MENIPPE RUMPHII (FABRICIUS, 1798) (DECAPODA: BRACHYURA: MENIPPIDAE) COLLECTED FROM PLANKTONIC SAMPLES Farhana S. Ghory Marine Reference Collection and Resource Centre, University of Karachi, Karachi-75270, Pakistan. e-mail: farhanaghory@yahoo.com ABSTRACT: The present paper is based on the description of the planktonic caught zoea I of Menippe rumphii (Fabricius, 1798). The planktonic materials have been obtained from Manora channel (Long. 66o 59'E and Lat. 24o 48'N) through the financial support of ONR (US Office of the Naval Research) project during 1993-1995. KEY WORDS: Menippe rumphii, Brachyura, Menippidae. INTRODUCTION The genus Menippe Ortmann, 1893 contains 19 species: Menippe adina Williams and Felder, 1986; Menippe frontalis A. Milne-Edwards, 1879; Menippe hirtipes (Lucas, in Jacquinot and Lucas, 1853); Menippe mercenaria (Say, 1818); Menippe nodifrons Stimpson, 1859; Menippe obtusa Stimpson, 1859; Menippe rumphii (Fabricius, 1798); Menippe convexa Rathbun, 1894; Menippe duplicidens Hilgendorf, 1878; Menippe fornasinii Bianconi, 1851; Menippe granulosa A. Milne-Edwards, 1867; Menippe granulosa de Man, 1888; Menippe leguillouii A. Milne-Edwards, 1867; Menippe martensii Krauss, 1843; Menippe nanus A. Milne-Edwards and Bouvier, 1898; Menippe ortmanni de Man, 1899; Menippe pagenstecheri Neumann, 1878; Menippe parvula Krauss, 1843; Menippe rudis A. Milne-Edwards, 1879. The present paper is based on the description of planktonic caught first zoeal stage of Menippe rumphii. The identifications of the present study was based on the previous work such as Prasad and Tampi (1957); Porter (1960); Kakati (1977); and Scotto (1979). The only species of the genus Menippe rumphii found in Pakistani waters. MATERIALS AND METHODS Planktonic sampling was carried out in Manora channel (Map 1) at fortnightly intervals during 1993-1995. Two stations, A and B, 5 kilometers apart were sampled. The samples included four 10 minute horizontal trawl using Bongo net of 300 micron mesh size equipped with a flow meter: AI (surface sample), AII (subsurface sample), BI (subsurface sample), BII (surface sample) at shallow depth 15'-20'. The samples were preserved in 5% formalin. Brachyuran larvae were sorted under binocular microscope Ogawa Seiki and transferred to 70% alcohol. Identification of these larvae were made to species level where possible by comparison with previously laboratory reared larvae and available literature. The preserved larvae were deposited in the Marine Reference Collection and Resource Centre, University of Karachi. Map 1. Map showing collection sites (solid circles). RESULTS DESCRIPTION OF THE LARVA Zoea I (Fig. 1A - K): Size.- TL = 1.28mm - 2.22mm Diagnostic Features.- Carapace (Figs. 1A, B).- Carapace smooth; rostral dorsal and lateral spines present; 1 pair of short setae present on either side of dorsal spine; eyes sessile. Fig. 1. Menippe rumphii (Fabricius, 1798) Zoea I: A, entire, lateral view; B, dorsofrontal view; C, antennule; D, antenna; E, mandible; F, maxillule; G, maxilla; H, I, maxillipeds I, II; J, abdomen , dorsal view; K, telson. Antennule (Fig. 1C).- Uniramous with 2 terminal aesthetascs and 2 terminal setae. Antenna (Fig. 1D).- Protopod slender, half of distal end of either side decorated with rows of spinules; exopod with 1 long and 1 small terminal seta. Mandible (Fig. 1E).- With well developed incisor and molar processes. Maxillule (Fig. 1F).- Coxal endite with 6 plumodenticulate setae; basial endite with 2 cuspidate setae and 3 plumodenticulate setae; endopod 2-segmented with 1,4 plumodenticulate setae, respectively. Maxilla (Fig. 1G).- Coxal endite bilobed with 5+4 plumodenticulate setae; basial endite bilobed with 5+4 plumodenticulate setae; endopod bilobed with 3+3 plumodenticulate setae on each proximal and distal lobes, respectively; exopod (scaphognathite) with 4 marginal plumose setae and 1 long stout plumose posterior process. Maxilliped I (Fig. 1H).- Coxa naked; basis with 10 plumodenticulate setae arranged 2,2,3,3 on medial margin; endopod 5-segmented with 3,2,1,2, 5 (2 subterminal + 3 terminal) plumodenticulate setae, respectively; exopod 2-segmented, distal segment with 4 terminal plumose natatory setae. Maxilliped II (Fig. 1I).- Coxa naked; basis with 4 plumodenticulate setae on medial margin; endopod 3-segmented with 0,1,4 (3 subterminal + 1 terminal) plumodenticulate setae, respectively; exopod 2- segmented, distal segment with 4 terminal plumose natatory setae. Abdomen (Fig. 1J).- Five somites; somite 2 with 1 pair of dorsolateral processes directed laterally; somite 3 with 1 pair of dorsolateral processes directed posteriorly; somites 3 and 4 with slightly developed posteriolateral angle; somite 5 longer than other somites and its lateral angles drawn into long spine; somites 1-5 each with 1 pair of posteriodorsal setae. Telson (Fig. 1K).- Bifurcated, each furca long, gradually curved inwards with a single pair of small lateral setae; posterior margin with 3 pairs of spinulate setae. REMARKS The taxonomy of M. rumphii is confused with M. nodifrons, a Caribbean Western Atlantic species. Investigation on larval morphology and development has helped to solve this issue. M. rumphii was earlier synonymized with M. nodifrons, descriptions of the zoeal stages of M. rumphii and M. nodifrons by Kakati (1977) and Scotto (1979), respectively, show that larvae of the 2 species differ considerably. In the first zoeal stage, M. rumphii exhibits elongated posterolateral processes on abdominal segment 5 that extend posteriorly to more than half the length of the telsonal furcae, which lack spines. The first zoea of M. nodifrons has similar posterolateral processes but these do not extend posteriorly beyond the fork of the telson; the telsonal furcae bear 1 dorsal and 2 lateral spines each. These differences are not apparent in later zoeal stages, but their presence in the first zoeal stage and the differences noted in the megalopa stage may be reason to question the synonymy of these 2 species (Martin, 1988). Recent revisions in taxonomy split the Xanthidae into seven separate families. The only species of Menippe whose complete larval development has been described are M. mercenaria by Porter (1960) and M. nodifrons by Scotto (1979). Among other species of Menippe only the first zoeal stage of the Indo-Pacific M. rumphii has been described (Prasad and Tampi, 1957). As indicated by Scotto (1979), the three congeners have a similar first stage, but differ in antennular aesthetasc number, setation of the maxillary coxal endite, setation of the basis and endopodite of the first maxilliped, and endopodite setation of the second maxilliped. However M. mercenaria is different having stout dorsal long abdominal spine. Five zoeal stages are found in M. rumphii. Scotto (1979) attributed the prolonged development of Menippe species and “tardy” appearance of both pleopod bud and mandibular palp to a retained primitive feature of this species. Table 1. Comparison between planktonic zoea I of Menippe rumphii (present study), earlier studied M. rumphii and its congeners larvae. Zoea I: Characters M. rumphii present study M. rumphii Prasad and Tampi (1957) M. rumphii Kakati (1977) M. mercenaria Porter (1960) M.nodifrons Scotto (1979) Antennule: aesthetascs 2 4 2 6 4 setae 2 setae no mention 1 seta no mention no mention Maxillule: coxal endite 6 setae 6 setae 7 setae 6 setae 7 setae Maxilla: basial endite 5+4 setae 5+4 setae 5+4 setae 5+4 setae 5+4 setae ACKNOWLEDGMENTS The planktonic samples of brachyuran larvae were obtained through the financial assistance of ONR (US Office of Naval Research) project. REFERENCES Kakati, V.S. 1977. Larval development of the crab, Menippe rumphii (Fabricus) as observed in the laboratory (Crustacea: Brachyura). Proceedings Symposium of warm water planktonic species. Publs. National Institute of Oceanography. Goa: 634-641. Martin, J.W. 1988. Phylogenetic significance of the brachyuran megalopa: evidence from the Xanthidae. Symposium Zoological Society of London, 59: 69-102. Prasad R.R. and P.R.S. Tampi, 1957. Notes on some decapods larvae. Journal of Zoological Society of India. 9: 22-39. Porter, H.J. 1960. Zoeal stages of the stone crab, Menippe mercenaria Say. Chesapeake Science. 1: 168-177. Scotto, L. E. 1979. Larval development of the Cuban stone crab, Menippe nodifrons (Brachyura: Xanthidae) under laboratory conditions with notes on the status of the family Menippidae. Fish Bulletin., U.S. 77: 359-386. PAGE 82 Pakistan Journal of Marine Sciences, Vol. 18(1&2), 2009. Ghory and Kazmi: First zoeal stage of Menippe rumphii PAGE 81 Pakistan Journal of Marine Sciences, Vol. 18(1&2), 77-82, 2009.