Abbreviated larval development of the freshwater prawn,Macrobrachium pilimanus (De Man, 1879) (Decapoda,Palaemonidae), reared in the laboratory

The larvae of the freshwater prawn, Macrobrachium pilimanus (De Man, 1879), were reared in the laboratory. Larval development was highly abbreviated, with two zoeal and one megalopal stages. Newly hatched larvae were benthic, with a tendency to cling on to roughened surfaces. All larval stages subsisted solely on endogenous yolk. Morphological and behavioural differences between the first zoea of this species and that of M. malayanum (Roux, 1934) are highlighted. The potential use of larval characters in taxonomy is also discussed.     

The complete larval development of the crab Pilumnus spinifer (Brachyura: Xanthoidea: Pilumnidae) reared in the laboratory

The complete larval development of the crab Pilumnus spinifer from the western Mediterranean was obtained in the laboratory. All four zoeal stages and the megalopa are described and illustrated. The morphological characters of the larvae of Pilumnus spinifer are compared with those of other known larvae of the genus. The zoeae of P. spinifer show the rostral spine longer than the antennule (excluding aesthetascs); short lateral spines present on the carapace, and the mediolateral processes are present only in abdominal somites 2 and 3. The megalopa is similar to that of other Pilumnidae species. The morphology of the larval stages shows very similar characteristics to that of those of P. hirtellus and P. dasypodus, among the described stages of the family.     

The larval development of Petalomera japonica (Henderson) (Decapoda,Dromiidae) reared in the laboratory

The complete larval development of Petalomera japonica (Henderson) is described, based on laboratory rearing. The species has two zoeal stages and a megalopa. Detailed comparisons are made with other dromiid larvae, particularly those of Petalomera wilsoni.     

The complete larval development of Sadayoshia edwardsii (37) (Decapoda: Anomura: Galatheidae) described from laboratory‐reared material

The complete larval development of Sadayoshia edwardsii (Miers, ) is described and illustrated from laboratory‐reared material. The development comprises four zoeal and one megalopal stages. Diagnostic zoeal characters of Sadayoshia are provided and these are compared with other galatheid genera for which the larval morphology is known. Zoeas of S. edwardsii are readily distinguished from those of other galatheid species by the setation of the maxillular endopod together with the basis and endopod of the first maxilliped. The megalop of S. edwardsii has a flattened, triangular‐shaped rostrum, which differs remarkably from that of the adult. Although the rostral shape resembles that of Galathea megalops, the armature of the lateral margins is different between megalops of the two genera. The present larval study suggests that Sadayoshia is more closely allied to Galathea than to Munida.     

Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions

To determine the early life history of the land hermit crab Coenobita brevimanus Dana, 1852, larvae were cultured individually in the laboratory. The zoeal and the megalopal stages are described and illustrated. The larvae developed through four planktonic zoeal stages to the megalopal stage. The major differences in the zoeal characters between C. brevimanus and other described Coenobita species were found in the armature of the pleomeres, whereas the character of pleomeres of C. brevimanus zoeae is the same as that of the coconut crab Birgus latro, a different genus in the same family. Morphological similarity was also found in segmentations of antennules and antennae in megalopae between C. brevimanus and the coconut crab. Megalopae of C. brevimanus were cultured in containers holding seawater and a hard substrate. These crabs migrate from the sea to land after developing a habit of acquiring gastropod shells.     

Larval development in Phimochirus roseus (Benedict) (Decapoda: Anomura: Paguridae) reared in the laboratory

The zoeal and megalopal stages of Phimochirus roseus (Benedict, 1892) are described and illustrated from material reared under laboratory conditions. Although the vast majority of zoeae of this species pass through only four larval stages before the moult to megalopa, an occasional fifth stage has been observed. Phimochirus roseus differs in a number of morphological attributes from the only other species of Phimochirus whose larvae have been described. However, their shared features are sufficiently characteristic to confirm the distinctiveness of the genus and its general developmental homogeneity.     

Larval development of Clibanarius antillensis Stimpson, 1859 (Crustacea: Anomura: Diogenidae) reared under laboratory conditions: a comparison between Panamanian and Brazilian populations

The larval developmental sequences of Clibanarius antillensis Stimpson from first zoea through to megalopa are compared between laboratory-reared populations from Panama and Brazil. Only four zoeal stages are recorded for the Panamanian population, in contrast to four or five for the Brazilian larvae. Other differences in morphology are discussed and illustrated. Variations resulting from geographic differences and/or differing laboratory conditions raise the question of the validity of phylogenetic hypotheses based on single laboratory rearing events.     

Complete larval development of the rare porcellanid crab,Novorostrum decorocrus Osawa, 1998 (Crustacea: Decapoda: Anomura: Porcellanidae), reared under laboratory conditions

The complete larval development of Novorostrum decorocrus Osawa, , is described and illustrated on the basis of laboratory‐reared material. Two zoeal stages and one megalop stage were recorded. Zoeas of N. decorocrus closely resemble those of N. indicum in the appendage characters, including the endopod of the maxillule with only a single stout seta on the distal margin. This character is unique to Novorostrum zoeas. However, N. decorocrus is distinguished from N. indicum by the setation on the endopod of the maxilla and the basis of the second maxilliped in both zoeal stages. The megalops of N. decorocrus are characterized by having a strongly elongate carapace, and differs considerably from the adults in the structure of the carapace, rostrum and third thoracic sternite, and in the armature of the pereiopods. The larval duration of N. decorocrus suggests that this rare porcellanid is more widely distributed than currently known.     

Zoeal development of Ethusa microphthalma smith, 1881 (Brachyura,Dorippidae) reared in the laboratory,with a comparison of other dorippid zoeae

The complete zoeal development of a dorippid crab in the subfamily Ethusinae is described for the first time from a known parental female. The ovigerous Ethusa microphthalma was collected in the northern Gulf of Mexico off Louisiana. Larvae passed through four zoeal stages, and the megalopa was reached in 59 days at 20°C and 35 ppt salinity. The larvae differ from those of the few other dorippids for which a zoea is known. Salient distinguishing features include long lateral carapace spines, the presence of six setae on the endopod of the maxillule and maxilla, and a spinose antennal exopod lacking projecting mid-length spines or setae. Zoeal characters are compared to those known for the allied subfamily Dorippinae, and all references to zoeae of the Dorippidae are tabulated.     

Larvae of Homola (Crustacea; Dromiacea) from South Africa

Summary

Five zoeal stages of probably a single Homola species from the S.E. Atlantic are described. There are six zoeal stages in this species, of which the first is lacking from the present series. The zoeae probably belong to Homola barbata Fabr., linking the stages previously described by Pike and Williamson (1960) and by Rice (1964), giving a good idea of the complete larval development of this genus. Anomalies in the published work, however, point to the existence of taxonomic problems not previously apparent from studies on the adults alone.

The absence of exopods from the legs of these larvae adds further support to the contention that the grouping of the Dromiidae and Homolidae together in the Dromiacea is artificial.     

The first zoeal stage of Harrovia albolineata Adams and White, 1848 (Crustacea: Brachyura: Pilumnidae), with a note on Eumedonine systematics

The first zoeal stage of Harrovia albolineata Adams and White, 1848 (subfamily Eumedoninae) is described. The zoea has a preponderance of pilumnid rather than parthenopid characters, and supports recent views that the Eumedoninae should be transferred from the Parthenopidae to the Pilumnidae. This zoeal stage is compared with those of Echinoecus pentagonus, the only other eumedonine whose larval development is known, and differs mainly in the structure of its abdomen and carapace. The status of the subfamily Eumedoninae is also briefly discussed.     

The larval development of the spider crab Rochinia gracilipes (Crustacea: Majoidea: Epialtidae: Pisinae) reared in the laboratory

The larval development of the spider crab Rochinia gracilipes Milne-Edwards, 1875 (Crustacea: Decapoda: Brachyura: Majoidea: Epialtidae: Pisinae) is described and illustrated from laboratory-reared larvae. Development consisted of two zoeal stages and one megalopa, following the typical pattern in Majoidea. Zoea I of R. gracilipes, R. debilis and R. carpenteri differed in lengths of the rostral spine of the carapace, in the number of setae and aesthetascs of several head appendages (exopods of antennules, endopods of maxillules, and endopods and scaphognathites of maxillae) and in the length of posterolateral processes of abdominal somites; lateral carapace spines were present only in R. carpenteri and pleopod buds only in R. debilis. Megalopae of Rochinia gracilipes and R. carpenteri differed in several notable characters: a dorsal spine and long rostrum of the carapace, as well as spines in coxa and ischium of pereiopods, appeared only in R. carpenteri, and podobranchiae of the 3rd maxilliped appeared only in R. gracilipes; they also differed in setation of abdomen and pleopods. The comparison of the available information on Pisinae larval development suggested that larval morphology would not help to accurately understand the phylogenetic relationships of this subfamily of spider crabs.     

Larval development of Apiomithrax violaceus (A. Milne Edwards, 1868) (Decapoda: Brachyura: Majoidea: Pisidae) reared in laboratory conditions,and a review of larval characters of Pisidae

Apiomithrax violaceus (A. Milne Edwards, 1868 Milne Edwards A 1868 Observations sur la faune carcinologique des Iles du Cap-Vert Nouvelles Archives du Muséum d'Histoire Naturelle, 4, 49–68, pls 16–18  [Google Scholar]) is a pisid majoid crab occurring in tropical and subtropical coastal waters of the eastern and western South Atlantic. Larval development consists of two zoeal stages and a megalopa. Beginning with the first zoea, the duration of each larval stage at 24°C was 3–8 (5±1), 3–5 (4±0.5) and 9–15 (11±2) days, the megalopa and first crab instar appearing 9–11 (10±1) and 20–27 (23±2) days after hatching, respectively. Larval characters agree with those proposed for the Majoidea, in having nine or more setae on the scaphognathite in the first zoea and well-developed pleopods in the second zoea. However, larvae of A. violaceus do not fit larval pisid features. Zoeal stages differ from most other Pisidae in having lateral spines, a long rostral spine extending beyond the antenna, two spines per telson fork and a dorsolateral process on the third abdominal somite. The megalopa differs in having a spine dorsally on the carapace and on the basial segment of the second pereiopod. Two characters that are potentially unique to Apiomithrax include a zoeal antenna with an exopod that is much longer than the protopod, and a rostral spine that is longer than the dorsal spine. These characters should facilitate the identification of this taxon and could also be useful for phylogenetic studies. A review of larvae of 28 species among 14 genera indicated that there is no apparent single larval character that differentiates the Pisidae, with more limited phylogenetic analyses suggesting that this is a paraphyletic group. Apiomithrax, Eurynolambrus, Pisoides, Rochinia and Scyra have the most divergent morphological characters within the family. The analysis and inclusion of additional taxa is likely to shed more light on the sister-group relationships of the Pisidae. However, based on the extent of morphological interspecific variability of known larvae it is likely that the group, as presently defined by adult morphology, is not monophyletic.     

The complete larval development of the Mangrove Ocypodid crab Macrophthalmus depressus Ruppell, 1830 (Brachyura: Macrophthalminae) reared in the laboratory

Macrophthalmus depressus larvae were reared in the laboratory using filtered estuarine water of salinity 25±1 ppt and temperature 29–31°C. M. depressus reaches the first crab stage after passing through five zoeal and a megalopa stage requiring 22–23 days. Each stage is described in detail and compared with other known species of the genus.     

Zoeal stages of Hiplyra variegata (Rüppell, 1830) (Crustacea: Brachyura: Leucosiidae) reared in the laboratory and collected from plankton at Al-Kharrar creek,central Red Sea

The zoeal stages of Hiplyra variegata are described and illustrated for the first time. Zoea I was obtained from an ovigerous female, and the zoea II and zoea III stages were captured in the plankton (their identity was confirmed by rearing some of them from earlier stages). Comparisons are made with the only other species of the genus of which larvae are known, i.e. H. platycheir. The presence of a lateral spine on the carapace of zoea I is one of the most important characters that can be used for easy recognition of H. variegata. It is important to note that the third zoea of H. variegata has four small spines at each posterolateral margin of the carapace, in contrast to three spines in other species.