The Early Larval Development of the Tropical Reef Lobster Enoplometopus Antillensis Lütken (Astacidea, Enoplometopidae) Reared in the Laboratory
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The early larval development of the tropical reef lobster Enoplometopus antillensis Lütken (Astacidea, Enoplometopidae) reared in the laboratory Fernando A. Abrunhosa 1; Max W. P. Santana 2 & Marcus A. B. Pires 1 1 Núcleo de Estudos Costeiros, Universidade Federal do Pará. Alameda Leandro Ribeiro, Aldeia, 68600-000 Bragança, Pará, Brasil. E-mail: [email protected]; [email protected] 2 Universidade Federal do Ceará. Avenida Mister Hull, Pici, 60455-760 Fortaleza, Ceará, Brasil. E-mail: [email protected] ABSTRACT. The early stages of the tropical reef lobster Enoplometopus antillensis Lütken, 1865 were described and illustrated in detail from specimens reared in the laboratory. Ovigerous females were captured in their habitat, at a depth of about 15 meters and transported to the laboratory. The larvae were reared in a recirculation water tank for approximately 15 days and then transferred to four 10 liters aquariums. The larvae were fed on Artemia sp. nauplii. Microalgae Dunaliella viridis was added daily to the culture. The larvae moulted seven times progressing through the zoea VIII. Megalopa stage was not achieved. The intermoulting period of each stage averaged from eight to 12 days. Morphological comparisons with previous reports are briefly discussed. KEY WORDS. Crustacean; larval description; morphology; ornamental. RESUMO. Desenvolvimento dos estágios iniciais da lagosta de recife tropical Enoplometopus antillensis Lütken (Astacidea(Astacidea, Enoplometopidae) cultivada em laboratório. Os estágios iniciais da lagosta tropical Enoplometopus antillensis Lütken, 1865 foram descritos e ilustrados a partir de espécimes cultivados em laboratório. Fêmeas ovígeras foram capturadas em seu habitat, na profundidade cerca de 15 metros e transportadas para o laborató- rio. As larvas foram cultivadas em tanques de água recirculante por aproximadamente 15 dias e, então transferidas para quatro aquários (capacidade 10 litros). As larvas foram alimentadas com náuplios de Artemia sp. recém eclodidos. A microalga Dunaliella viridis AUTOR foi diariamente adicionada no cultivo. As larvas mudaram sete vezes alcançando o zoea VIII. O estágio megalopa não foi obtido. O período de intermuda de cada estágio variou de cerca de oito a 12 dias. Comparações morfológicas com trabalhos anteriores são brevemente discutidas. PALAVRAS-CHAVE. Crustáceo; descrição larval; morfologia; ornamental. The genus Enoplometopus A. Milne-Edwards, 1862 comprises have recognized the Enoplometopus as a very appreciated orna- 11 species, but only two are found in the Atlantic ocean, E. mental species because of its dazzling coloration, economic value antillensis Lütken, 1865 and E. callistus Intès & Le Loeuff, 1970 and high demand. Unfortunately, little information on larval (POUPIN 2003, AHYONG, & O’MEALLY 2004). The first is the most com- and adult biology is available. mon species found in the Atlantic and the only Enoplometopus Because studies on the culture of ornamental decapods lobster reported in the tropical West Atlantic (POUPIN 2003). have improved scientific understanding, the larval development The nomenclature and classification of this genus have and proper culture technologies have been developed for sev- been controversial, most likely due to its rarity and morpho- eral species (RHYNE et al. 2005). However, many attempts to logical similarities among related species which have been cap- culture various species of decapods have failed, one of which is tured (MERINO & LINDREY 2003). Thus, the Enoplometopus have the Enoplometopidae. Perhaps this is because only a few hob- been classified as an astacidean, an axiid thalassinidean or a byists have time and motivation to work on species resistant sister to the Fractosternalia + Homarida (AHYONG & O’MEALLY or difficult to culture. IWATA et al. (1991) reported the first at- 2004). However, recent revisions and studies on the phylog- tempt of Enoplometopus with the species E. occidentalis in cul- eny and molecular analyses have placed it in Enoplometopidae ture, in which eight zoeal stages were achieved. (MARTIN & DAVIS 2001, AHYONG & O’MEALLY 2004). A relevant aspect to be considered is the study on mor- In recent years, there has been an increase in the aquarium phological development of cultured lobster. Observation of trade industry (PENHA-LOPES et al. 2006). The marine aquarists larval crustaceans has contributed to the identification of new Revista Brasileira de Zoologia 24 (2): 382–396, junho 2007 The early larval development of the tropical reef lobster Enoplometopus antillensis... 383 species and facilitated their biological studies. The present study DESCRIPTION OF THE LARVAL STAGES describes and illustrates in detail the early larval stages of E. Zoea I (Fig. 2) antillensis reared in the laboratory. Morphological comparisons Carapace (Fig. 2): length (CL) 1.89 mm (1.89-1.90 mm): with larvae of its congeneric species E. occidentalis previously rostrum long, straight and gutter shaped, surpassing antennal described by IWATA et al. (1991) are briefly discussed. scale with 6+6 small denticles laterally; carapace smooth; eyes MATERIAL AND METHODS sessile. Antennule (Fig. 10): elongate; unsegmented with four Ovigerous females of E. antillensis were captured at Fortim aesthetascs and one plumose subdistal seta. Beach (04º14’S, 37º43’W), Ceará, Brazil, at a 15 m depth. They Antenna (Fig. 11): propod lacking seta; exopod segmented were carethlly transported in small polyethylene bags with sea distally showing 8-9+1 plumose setae; endopod shorter than water. In the laboratory, females were placed in 60 l aquariums exopod with three long plumose setae. with seawater (salinity 33-36‰ and pH 8.0). Maxillule (Fig. 12): exopodite with three setae; endopod The larvae were reared in circular tanks with continuous 3-segmented, distal segment with 2+2 distal plumose setae, water circulation similar to those used for culture of several proximal and medial segments with two and two distal setae species of spiny lobsters (KITTAKA 1994). The tanks were made respectively; basal endite with two strong cuspidate setae and with acrylic (70 cm Ø and 30 cm depth). Larvae were main- two plumose setae; coxal endite with 5+2 plumose setae. tained in this recirculation system at a density of 10 larvae/l Maxilla (Fig. 13): scaphognathite with 4+1 plumose se- for approximately 15 days and then transferred to four 10 l tae; endopod well developed and 5-segmented, with 3,2,2,1,2 aquariums at the same density. The larvae were fed with Artemia long plumose setae; basal and coxal endites bilobed with long sp. nauplii. Microalgae Dunaliella viridis was added daily to the and plumose setae (as illustrated). culture at a concentration of 150 x 104 cell/ml, in order to First maxilliped (Fig. 14): endopod short, 4-segmented maintain the water quality by recycling inorganic nutrients, with 2,2,3,4 setae; basipod bearing eight setae; coxal endite fixing carbon dioxide and supplying dissolved oxygen to the with two setae, exopod with four natatory setae. aquaculture systems by its photosynthetic activities. Tempera- Second maxilliped (Fig. 15): endopod 4-segmented with ture, salinity and pH were monitored using a multi-parameter 3,2,2,4 setae, distal segment (one long spine and three terminal portable equipment and dissolved ammonium with a tetra setae); basipod with four setae; exopod with four natatory setae. ammonia kit. Salinity and temperature values in the culture Third maxilliped (Fig. 16): endopod 4-segmented, (proxi- were approximately 35‰ and 27-29°C, respectively. mal segment fused with basipod) with 2+2,3,2,2+2 setae (one Exuviae and death larvae were preserved in a glycerol + strong and three long terminal and one subterminal setae); ethylic alcohol 70% (1:1) solution after each moulting. About 10 basipod with four setae; exopod with four natatory setae. larvae and exuviae of each stage were dissected and illustrated. Abdomen (Fig. 2): with six abdominal somites lacking The carapace length (CL) was measured from the ocular spines, 6th abdominal segment long and fused with telson. region to the posterior midpoint region of the carapace. The Telson (Fig. 17): bifurcate showing an accentuated me- illustrations and measures of the larvae were made under a dial depression with 5+1 plumose setae and one spine on each binocular Zeiss microscope equipped with a micrometer disc. furcal branch. Zoea II (Fig. 3) RESULTS Carapace (Fig. 3): Length (CL) 2.24 mm (1.23-2.25 mm): Larval culture rostrum with 8+8 small denticles laterally; carapace showing a In the laboratory, hatched larvae were obtained from pterigostomial spine elongate; eyes stalked. three females. The larvae hatch as a prezoea (Fig. 1) in which Antennule (Fig. 18): with five aesthetascs and one plu- they persist for less than one hour but many prezoea failed to mose subdistal seta. moult into zoea I. Moulting of the 1st to the 2nd stage occurred Antenna (Fig. 19): propod segmented with endopod with 7–12 days after being placed in tanks; the 2nd to the 3rd and 3rd 1 small seta; exopod segmented distally showing 8-9+1 plu- to the 4th stages averaged seven and eight days, respectively. mose setae; endopod shorter than exopod with three long plu- The intermoulting period for the subsequent stages was not mose setae. possible to determine accurately since the larvae were not reared Maxillule (Fig. 20): exopodite with four setae; endopod individually. High mortality occurred on the 3rd culture day in 3-segmented; basal endite with two cuspidate and three plu- which approximately 60% of the larvae died. mose setae; coxal endite with nine plumose setae. Morphological malformations were frequently observed Maxilla: similar to the previous stage. in the mouthpart of the zoeae and it appeared to be related to First maxilliped (Fig. 21): endopod short, 4-segmented the individual adaptation to the laboratorial conditions. This with 2,2,3,4 setae; basipod bearing seven setae; coxal endite fact needs to be researched. with five setae, exopod with four natatory setae. Revista Brasileira de Zoologia 24 (2): 382–396, junho 2007 384 F. A. Abrunhosa et al. 1 2 34 5 Figures 1-5.