ALLOMETRIC GROWTH, SEXUAL MATURITY, AND ADULT MALE CHELAE DIMORPHISM IN AEGLA FRANCA (DECAPODA: ANOMURA: AEGLIDAE)

Allometric growth analysis on chelac dimensions vs. carapace length (CL) was employed to estimate average size at the onset of morphometric maturity (= puberty molt) and sexual dimorphism regarding the pair of chelae in Aegla franca. Males attain morphometric maturity (12.15 mm of CL) at a larger size than females (10.93 mm of CL). After the puberty molt, an additional change in the allometry level regarding chelae dimensions was detected in adult males (average CL = 19.00 mm). As a result, two sequential morphotype groups of adult males, herein designated as morphotype I and morphotype II, were recognized according to the state of development of the pair of claws. We postulate that the second change in this allometry level is related to functional maturity in this sex, based on the following observations: 1) temporal variation in the proportion between the two morphotype groups reveals that morphotype II individuals make up most of adult males in the population at the beginning of the seasonal reproductive period of the species, and 2) morphotype II males show a more robust pair of claws as compared to the predecessor morphotype, which might represent an advantageous trait in reproductive competition. Males and females of Aegla franca are heterochelous with handedness preponderance of the left chela. Claw size is a distinct dimorphic trait in this species, being significantly larger in male specimens.

Allometric growth of two species of Ephemeroptera from Neotropical mountains streams

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A comparison of the allometric growth in Uca leptodactyla (Crustacea : Brachyura : Ocypodidae) from two subtropical estuaries

The allometric growth of Uca leptodacyla from two distinct subtropical estuaries on the Brazilian coast was evaluated concerning its growth pattern and size at onset of sexual maturity. Females attained maturity at similar sizes in both sites (4.1 mm of carapace length in Indaia and 4.2 mm in Ubatumirim), while males differed slightly. They reached the size at sexual maturity of 5.3 mm of carapace length in Indaia and 4.6 mm in Ubatumirim. Growth pattern is Usually similar among crabs from distinct Sites while size at sexual maturity is frequently different. However, in the case of U. leptodacyla it did not occur, probably due to the strong habitat similarity and intrinsic features of this species.

Allometric growth in the fiddler crab Uca thayeri (Brachyura, Ocypodidae) from a subtropical mangrove

The relative growth of U. thayeri was studied for a subtropical mangrove population in the estuary of the Comprido and Escuro rivers, Ubatuba, São Paulo State, Brazil. The evaluation of the morphological sexual maturity of U. thayeri was performed using the allometric technique. Remarkable ontogenetic changes were observed in the allometric growth of the male major cheliped and the female abdomen, indicating that these structures are closely connected to the timing of sexual maturity. For males, the relative-growth analysis of cheliped propodus length rendered an estimate of 13.8 mm of carapace width for the size at onset of sexual maturity. A distinct growth pattern was observed for the abdomen of U. thayeri females. It has a wide puberty size range (from 10.7 to 16.8 mm of CW) compared to other brachyurans previously studied. Thus, the females' abdominal growth can be represented by three growth phases: immature, transitional, and mature. The major cheliped is the fight one in 50% of males. The median length of the male major cheliped did not differ between right- and left-handed crabs.

Allometric growth of non-carcass components in crossed lambs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Allometric growth of a common Nassariidae (Gastropoda) in south-east Brazil

The allometric growth of two groups of Nassarius vibex on beds of the bivalve Mytella charruana on the northern coast of the State of Sao Paulo, was evaluated between September 2006 and February 2007 in the bed on Camaroeiro Beach, and from March 2007 to June 2007 at Cidade Beach. The shells from Camaroeiro were longer and wider and had a smaller shell aperture than those from Cidade; a principal components analysis also confirmed different morphometric patterns between the areas. The allometric growth of the two groups showed great variation in the development of individuals. The increase of shell width and height in relation to shell length did not differ between the two areas. Shell aperture showed a contrasting growth pattern, with individuals from Camaroeiro having smaller apertures. The methodology based on Kullback-Leibler information theory and the multi-model inference showed, for N. vibex, that the classic linear allometric growth was not the most suitable explanation for the observed morphometric relationships. The patterns of relative growth observed in the two groups of N. vibex may be a consequence of different growth and variation rates, which modifies the development of the individuals. Other factors such as food resource availability and environmental parameters, which might also differ between the two areas, should also be considered.

Allometric growth of two species of Ephemeroptera from Neotropical mountains streams

The present study evaluated the relative growth and allometry of Massartella brieni Lestage and Thraulodes sp. (Leptophlebiidae: Ephemeroptera). The morphometric analysis was based on 23 measurements and was conducted using a multivariate approach. Throughout postembryonic ontogeny, all of the head measurements, including those of the mouthparts, exhibited negative allometric growth. The mesothorax and wing pad exhibited positive allometric growth. The hind legs lengths in M. brieni and the fore and hind legs lengths in Thraulodes sp. exhibited positive allometry. The abdominal length in these two species exhibited positive allometric growth. Positive allometry was also observed along the abdomen width for M. brieni, and isometry was observed for Thraulodes sp. The relative strengthening of the thorax (in preparation for the winged stage) and the relative increase in the abdomen (which may be related to the development of the reproductive structures) during growth indicate that many of the structures that exhibit positive allometric growth are related to the transition from the aquatic to the adult stage of development.

Relative growth and morphological sexual maturity of Chasmagnathus granulatus (Crustacea, Varunidae) from a mangrove area in southeastern Brazilian coast

The relative growth and morphological sexual maturity of Chasmagnathus granulatus Dana, 1851 are presented for the first time to a mangrove population. The crabs were obtained during low tide periods, in the mangrove of Jabaquara Beach, Paraty, Rio de Janeiro, Brazil. All crabs in intermolt stage were sexed and had their body parts measured as follows: body height (BH), carapace length (CL) and width (CW), major cheliped propodus height (PH) and length (PL) for each sex, gonopod length (GL) and abdomen width (AW) for males and females, respectively. The relative growth was described using the allometric equation y=ax b and the size at onset sexual maturity was achieved using the software Mature I. The size of specimens ranged from 4.1 mm to 39.5 mm CW. The growth pattern was different between sexes in the cheliped relationships; the relationships BH vs. CW evidenced positive allometry for juveniles; PL vs. CW and PH vs. CW positive allometry for most crabs except juvenile females; AW vs. CW and GL vs. CW evidenced positive allometry for juveniles and isometry for adults. The relationships that best indicated the change from the juvenile to the adult phase were PH vs. CW for males and AW vs. CW for females. The size in which 50% of males from this population are mature is at 19.7 mm of CW (F=144.14; p<0.05) and for females it is at 19.2 mm of CW (F=166.54; p<0.05). The sizes obtained in this mangrove population are larger than those from previous studies, that could be attributed to a species plasticity concerning the habitat structure.

Relative growth and sexual maturity of the freshwater shrimp Palaemon pandaliformis (Crustacea, Palaemonidae) in northeastern of Brazil (Canavieiras, Bahia)

This study comprises the description of relative growth and sexual maturity of a population of Palaemon pandaliformis Stimpson, 1871 in Salsa River (Northeastern Brazil). Samples were collected monthly between September 2009 and August 2010. Females were larger, heavier, and showed a greater allometric coefficient (b) than male specimens. Only carapace length vs. pleura length in females presented a significant difference in the relative growth pattern, indicating a puberty moult. This relationship is strictly correlated to reproduction and its success rate in female shrimps. Estimated carapace length in 50% of mature females (CL50) was 4.53 mm. It was not possible to compare obtained CL50 results due to a lack of studies on this species. Comparison was based on the size of the smallest captured ovigerous female (3.81 CL mm), which is within the scope of recorded size for estuaries located in higher latitudes. This study reveals the lack of research on this genre in freshwater environments on a national and global scale.

The relative growth and sexual maturity of the freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae) in the northwestern region of the state of São Paulo

The aim of the present study was to determine the size at sexual maturity in the freshwater crab Dilocarcinus pagei Stimpson, 1861, from a population located in Mendonça, state of São Paulo, Brazil. The crabs were sampled monthly (July 2005 to June 2007), at Barra Mansa reservoir. The specimens were captured manually or in sieves passed through the aquatic vegetation. The crabs were captured and separated by sex based on morphology of the pleon and on the number of pleopods. The following dimensions were measured: carapace width (CW); carapace length (CL); propodus length (PL); and abdomen width (AW). The morphological analysis of the gonads was used to identify and categorize individuals according to their stage of development. The morphological maturity was estimated based on the analysis of relative growth based on the allometric equation y = ax b. The gonadal maturity was based on the morphology of the gonads by the method CW50 which indicates the size at which 50% of the individuals in the population showed gonads morphologically mature to reproduction. The biometric relationships that best demonstrated the different patterns of growth for the juvenile and adult stages were CW vs. PL for males and CW vs. AW for females (p<0.001). Based on these relationships, the estimated value to morphological sexual maturity was 21.5 mm (CW) in males and 19.7 mm (CW) in females. The determination of the size at sexual maturity and the adjustment of the data based on the logistic curve (CW50) resulted in a size of 38.2 mm for males and 39.4 mm for females (CW). Based on the data obtained for sexual maturity for D. pagei, we can estimate a minimum size for capture of 40 mm (CW). This minimum size allows at least half of the population to reproduce and retains the juveniles and a portion of the adults in the population.

Comparative allometry growth of some marine fish digenetic trematodes

Allometric growth variation was compared for Plagioporus idoneus, Lepocreadium pegorchis, Opecoeloides furcatus, Bacciger israelensis, Aphanurus stossichi and Parahurleytrema trachinoti collected from East Mediterranean fishes. The pharynx, the oral and the ventral sucker diameters always showed a negative allometry. The other parameters tested were variable with the species. We study the effects of some environmental factors: the influence of the host species is analysed in Plagioporus idoneous, wich parasitizes Oblada melanura, Diplodus sargus and D. vulgaris and in Lepocreadium pegorchis, wich parasitizes Pagellus erythrinus, Lithognathus mormyrus and Spicara smaris; the influence of the microhabitat and the intensity of infection is analysed in Bacciger israelensis and Aphanurus stossichi, both parasites of Boops boops. We report significant differences with the host species, for the allometric growth of the testes; the effect of the microhabitat was revealed by the hindbody allometric value; no significant difference was detected in relation with the intensity of infection.

Development and growth of the early juveniles of the spider crab Maja squinado (Brachyura: Majoidea) in an individual culture system

The spider crab Maja squinado is an endangered Mediterranean species; therefore, culturing it successfully is essential for developing restocking programs. The survival, growth and development of post-larval stages (juvenile crabs, C1-C8) were studied using larvae obtained from adult individuals collected in the Catalan Sea. The juvenile crab stages were cultured individually from a megalopal stage using a semi-open recirculation system to obtain the precise growth data of each juvenile crab stage until C8. Development up to C8 at 20ºC lasted 154±10 days. Survival from C1 to C8 was 5.8 %. Moult increment values in cephothoracic length were similar in all the crab stages (21-35 %). Intermoult duration (9±1 in C1-C2 to 51±8 days in C7-C8) increased sharply from juvenile stage 5. Males and females can be distinguished from C4 based on sexual dimorphism in the pleopods and the presence of gonopores. The allometric growth of the pleon is sex-dependent from C4, with females showing positive allometry and males isometric growth. The juvenile growth rate was lower compared with that of the previously studied Atlantic species Maja brachydactyla.

Postlarval stages and growth patterns of the spider crab Pyromaia tuberculata (Brachyura, Majidae) from laboratory-reared material

The spider crab Pyromaia tuberculata was introduced into southeastern Brazil; ovigerous material was collected and reared in the laboratory. Morphologic changes and growth patterns of post-larval development are reported. Results show that within-stage size variation is lowest in mature stages, especially in the case of females in which there is an apparent size threshold for the last juvenile stages to undergo the puberty molt. A prepuberty molt taking place at the fourth crab stage is indicated by analyzing the allometric growth of the abdomen in females. In contrast, the same procedure using the allometric growth of chelae failed in detecting both the prepuberty and puberty molts in males. Conversely to females, which develop a complex brood chamber at the puberty molt, the enlargement of chelae was not consistent in all postpuberty males. The short instar sequence of this species, in no case exceeding nine stages, is marked by conspicuous morphologic alterations achieved at each molt. Almost all stages can be identified by examining diagnostic features of rostrum, abdomen, sternum, and pleopods.

Juvenile development and growth patterns in the mud crab Eurytium limosum (Say, 1818) (Decapoda, Brachyura, Xanthidae) under laboratory conditions

The post-larval development of the mud crab Eurytium limosum was studied under laboratory conditions by using the offspring of ovigerous females collected at the Comprido River mangrove, SP, Brazil. The first crab stage is fully described and the juvenile development, until crab stage 10, is examined with emphasis on morphological change, sexual differentiation and growth patterns. The carapace of the first crab stage is nearly square as observed in other xanthids, becoming similar to adults only at stage 15. The sexes can be distinguished from stage four, based on the number of pleopods and their morphology. While the intermoult period increases, the moult percentage decreases at each stage. The abdominal allometric growth is sex-dependent, with males showing a negative (b=0.71) and females an isometric (b=0.95) relative growth pattern. Male gonopods undergo a positive allometric growth, and their shape changes remarkably until sexual maturity. The cheliped dentition can be observed after stage 4. Regardless of sex, most crabs have a molariform right cheliped, which is thought to aid the handling of asymmetric prey such as gastropods.

Relative growth and morphological sexual maturity of Chasmagnathus granulatus (Crustacea, Varunidae) from a mangrove area in southeastern Brazilian coast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)