Crustaceana

Shenoy, Shakuntala; Paul, Ravindra; Sankolli, K.N.

doi: 10.1163/156854093X00775pmid: N/A

<jats:sec><jats:title>Abstract</jats:title><jats:p>The porcellanid crabs in their larval phase show typical anomuran features but develop a crab-like form from megalopa through the juvenile instars. However, the adult species characters are not yet noticeable in the juvenile phase thus leading to confusion in identity both at specific or even at generic level. With attainment of the crab-like form, the reproductive appendages, like male pleopods, show a brachyuran pattern. In absence of external sexual dimorphism, sex determination is difficult in this group. Very little information is available as to how and when the sexual appendages start developing in Porccllanidae. With the purpose of tracing the development of the adult taxonomic characters and that of the reproductive appendages (and sex differentiation), the present paper describes the juvenile laboratory development of two porcellanid crabs, viz. Petrolisthes rufescens (Heller) up to instar III and Pisidia gordoni (Johnson) up to instar IV. Taxonomic features: In both the species the definitive adult features like those of the carapace front and its armature, the chelipeds and other pereiopods, the sternite of the third maxillipeds, etc., develop in the third instar. Sexual appendages: (a) In Petrolisthes rufescens the primary pleopods get totally reduced at least up to instar III and, therefore, the sexual appendages appear to be developing as a secondary series of pleopods, particularly in the female. (b) In Pisidia gordoni, at least in the male, differentiation starts from instar II onwards with the first pleopod modifying into a male appendage, while the remaining pleopods gradually become reduced.</jats:p> </jats:sec>

Garcia Machado, Erik; Oliva Suarez, Mario; Dennebouy, Nicole; Monnerot, Monique; Mounolou, Jean-Claude

doi: 10.1163/156854093X00711pmid: N/A

<jats:sec><jats:title>Abstract</jats:title><jats:p>Part of the mitochondrial 16S-ribosomal RNA gene (around 400 nucleotides) of Penaeus notialis and Penaeus schmitti has been amplified and sequenced. The comparison of sequences reveals an 11% nucleotide divergence between the two species. When compared with that of the homologous fragment in Artemia salina and Drosophila yakuba, the secondary structure appears well conserved in spite of high nucleotide divergence due to numerous substitutions and additions/deletions. Sequences have been obtained for six individuals of P. notialis belonging to the same population, their comparison shows a 0.7% nucleotide diversity.</jats:p> </jats:sec>

Pessani, Daniela

doi: 10.1163/156854093X00748pmid: N/A

<jats:sec><jats:title>Abstract</jats:title><jats:p>The larvae of 29 species of Natantia (Decapoda) have been collected in Tigullio Gulf (Ligurian Sea). In addition, four different "types" of unidentified first zoeac of Pandalidae were recognized and discussed. Using the similitude index of Sörensen (1948), it was possible to distinguish main groups of spring-summer and annual species and small groups of late-summer and autumn-winter ones. Comparison of the results obtained with data from other works on Mediterranean planktonic decapod larvae reveals some discrepancies regarding the number of collected species and their distribution throughout the year. These different results could be due to different collecting methods, environmental conditions, and geographical distribution of the adults. The work shows the importance of studying planktonic larvae for a better knowledge of larval development and life history of Crustacea Decapoda.</jats:p> </jats:sec>

Adao, Helena; Marques, Joao Carlos

doi: 10.1163/156854093x00766pmid: N/A

AbstractPopulation structure and recruitment of Procambarus clarkii were studied from 1989 to 1991 in a freshwater reservoir in southern Portugal. Two distinct recruitment periods were observed, the main one from October to February and a less significant one during spring and summer. With regard to population structure, juveniles were clearly dominant in January and February. The present results suggest that more than one generation per year may occur under favourable climatic conditions.

Paul, Ravindra; Sankolli, K.N.; Shenoy, Shakuntala

doi: 10.1163/156854093x00775pmid: N/A

AbstractThe porcellanid crabs in their larval phase show typical anomuran features but develop a crab-like form from megalopa through the juvenile instars. However, the adult species characters are not yet noticeable in the juvenile phase thus leading to confusion in identity both at specific or even at generic level. With attainment of the crab-like form, the reproductive appendages, like male pleopods, show a brachyuran pattern. In absence of external sexual dimorphism, sex determination is difficult in this group. Very little information is available as to how and when the sexual appendages start developing in Porccllanidae. With the purpose of tracing the development of the adult taxonomic characters and that of the reproductive appendages (and sex differentiation), the present paper describes the juvenile laboratory development of two porcellanid crabs, viz. Petrolisthes rufescens (Heller) up to instar III and Pisidia gordoni (Johnson) up to instar IV. Taxonomic features: In both the species the definitive adult features like those of the carapace front and its armature, the chelipeds and other pereiopods, the sternite of the third maxillipeds, etc., develop in the third instar. Sexual appendages: (a) In Petrolisthes rufescens the primary pleopods get totally reduced at least up to instar III and, therefore, the sexual appendages appear to be developing as a secondary series of pleopods, particularly in the female. (b) In Pisidia gordoni, at least in the male, differentiation starts from instar II onwards with the first pleopod modifying into a male appendage, while the remaining pleopods gradually become reduced.

Amaro Pinheiro, Marcelo Antonio; Fransozo, Adilson

doi: 10.1163/156854093x00801pmid: N/A

AbstractArenaeus cribrarius is a mainly tropical crab that occurs in the Western Atlantic Ocean, Brazil being its type-locality. The species ranges from Vineyard Sound, Massachusetts, USA to La Paloma, Uruguay. Information about this species is scarce. The relative growth ofA. cribrarius was analyzed, based on some morphometric relations, where the carapace width, excluding lateral spines (CW), was used as an independent variable. A total of 403 specimens (189 males and 214 females), was collected in Ubatuba, State of São Paulo, Brazil, with otter-trawls. The animals were sexed and sorted to maturation phase (juvenile or adult). Some measurements were made: carapace (length and width excluding lateral spines), abdomen (greatest width of the fifth somite in females and the sixth in males) and major chela (greatest length, width and height, dactylus length). This study was made by the application of the power function (y=a.xb) which was fitted to the data and the pattern of growth established for each parameter by the "b"-value (constant of allometry), as positive allomctry (b>1), negative allometry (b<1) or isometry (b=1). The morphometric relations of the carapace showed a tendency to isometry. In females, the abdominal width grew in positive allometry, higher in juveniles (b= 1.33) than in adults (b=1.18). In this case, an overlap and discontinuity was noticed between the phases over a carapace width range of 55 to 70 mm, where the puberty molt occurs. The majority of relationships showed that the major chela of the males grew in positive allometry, however, the greatest allometric difference between the phases was observed towards the propodus length with 1.09 as juvenile and 1.26 as adult "b"values. In the males, this variable showed an inflection between the CW range of 45 to 55 mm, where the transition to the maturation phase occurs. The relative growth of this species is similar to those of previously studied species. This indicates, that the propodus length and the abdominal width are the morphometric variables most appropriate to estimate the size at the beginning of the sexual maturity for males and females of this species, respectively.

Shenoy, Shakuntala; Jalihal, D.R.; Sankolli, K.N.

doi: 10.1163/156854093X00739pmid: N/A

<jats:sec><jats:title>Abstract</jats:title><jats:p>The aesthetascs of the prawns are chemo- and mechano-receptors which exhibit diversity in number and shape depending on habitat and environment. In marine forms (both adults and larvae) they arc more numerous, longer, slender and uniformely thin wallcd. In adults of freshwater prawns they are fewer, shorter, divided into a thick walled stalk and a thin distal cob-like portion. However, they arc structurally different and positioned differently in the atyid genus Caridina and palaemonid genus Macrobrachium. Further, Caridina exhibits sexual dimorphism with males possessing a greater number of aesthctascs-bearing segments than females, unlike Macrobrachium which does not show such dimorphism. As far as larvae are concerned, in the 'inland species' of both genera, which complete their metamorphosis purely in freshwater, the 'freshwater- type aesthetases' appear in the first and second zoeal stages in totally or partially abbreviated type of development respectively. On the other hand, the early zoeal stages of 'coastal species' possess 'marine-type aesthetascs' indicating salinity dependence for their successful metamorphosis. These aesthetascs get shortened in late larval stages and subsequently get transformed into typically 'freshwater type' from postlarva onwards. A unique kind of 'branched larval aesthetascs' has been observed in two species of Macrobrachium. Thus, despite their common sensory function, the aesthetascs exhibit structural variations depending on environment and also play an important role as salinity indicators in the culture of freshwater prawns.</jats:p> </jats:sec>

Chaudhari, K.J.; Jalihal, D.R.

doi: 10.1163/156854093X00757pmid: N/A

<jats:sec><jats:title>Abstract</jats:title><jats:p>Despite the advancement in prawn culture technology in several parts of the world, India will be still depending on wild seed for prawn farming for some more time. In this context, selective stocking is very important. Yet, practically no information is available on the correct identification of juvenile or seed stage (size: 6 to 60 mm) although a lot of work is done on larval and postlarval stages. Various morphological changes, including colouration, take place during juvenile phase rendering the segregation of seed of different species even more difficult. The present work, based on seed collection from the wild and supplemented by laboratory observations over a period of two years, gives a detailed field key for the following 11 species belonging to 4 genera occurring along the Konkan coast (west coast of India): (1) Penaeus (Penaeus) monodon, (2) P. (P.) semisulcatus, (3) Penaeus (Fenneropenaeus) merguiensis, (4) P. (F.) indicus, (5) Penaeus (Marsupenaeus) japonicus, (6) Metapenaeus dobsoni, (7) M. monoceros, (8) M. affinis, (9) M. moyebi, (10) Parapenaeopsis cornuta, (11) Metapenaeopsis sp. The key is based on colour in live condition, habitat and salinity preference, swimming and burying behaviour, morphological, meristic and morphometric studies.</jats:p> </jats:sec>

Pipitone, Carlo; Tumbiolo, Maria Linda

doi: 10.1163/156854093x00784pmid: N/A

Abstract78 species of decapod and stomatopod crustaceans were collected during a two-year survey on the trawlable bottoms of the Sicilian Channel. Bathymetric range, size range, size of the smallest ovigerous females and their period of occurrence are given. Some brief remarks on Parasquilla ferussaci, Pontophilus norvegicus and Maja goltziana are made.

Garcia Machado, Erik; Dennebouy, Nicole; Oliva Suarez, Mario; Mounolou, Jean-Claude; Monnerot, Monique

doi: 10.1163/156854093x00711pmid: N/A

AbstractPart of the mitochondrial 16S-ribosomal RNA gene (around 400 nucleotides) of Penaeus notialis and Penaeus schmitti has been amplified and sequenced. The comparison of sequences reveals an 11% nucleotide divergence between the two species. When compared with that of the homologous fragment in Artemia salina and Drosophila yakuba, the secondary structure appears well conserved in spite of high nucleotide divergence due to numerous substitutions and additions/deletions. Sequences have been obtained for six individuals of P. notialis belonging to the same population, their comparison shows a 0.7% nucleotide diversity.