Ecological distribution of the shrimp Pleoticus muelleri (Bate, 1888) (Decapoda: Penaeoidea) in southeastern Brazil

The abundance and ecological distribution of the shrimp Pleoticus muelleri as a function of certain environmental factors were investigated from January 1998 through December 1999 in the region of Ubatuba, São Paulo, Brazil. The collections were made monthly in the bays of Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). Each bay was divided into six sampling transects, four transects parallel to the shoreline and two near the rocky shores on the opposite side. We employed a commercial shrimp boat equipped with two double-rig nets. A total of 6252 shrimp were collected, including 3321 from MV, 1467 from UBM, and 1464 from UBA. Most of the shrimp were caught in the deeper, higher-salinity areas. The high abundance of P. muelleri observed in the southern part of the region studied was related to a sediments with a higher percentage of silt and clay. The numbers of P. muelleri were positively correlated with periods of cooler temperatures. Thus, temperature and the type of sediment were determinant factors in the distribution of P. muelleri in this region.     

Aspects of the biology of the pygmy ribbontail catshark Eridacnis radcliffei (Proscylliidae: Carcharhiniformes) from the south-west coast of India

Biological data are presented for the pygmy ribbontail catshark Eridacnis radcliffei based on specimens collected from the by-catch of the commercial deep-sea shrimp trawl fishery operating in the Arabian Sea off the south-west coast of India. A total of 549 individuals, from 101 to 257 mm total length (L(T) ) and 2·2 to 56 g, were collected. The L(T) at first maturity (L(T50) ) of females and males was estimated at 183 and 170 mm, respectively, and analysis of stomach contents revealed that E. radcliffei feeds primarily on crustaceans.     

Mitochondrial phylogenomics reveals insights into taxonomy and evolution of Penaeoidea (Crustacea: Decapoda)

The taxonomy and phylogeny of Penaeoidea have long been fraught with controversy. Here, we carried out the first mitochondrial phylogenomic analysis on all the penaeoid families and tribes, including nine newly sequenced and 14 published mitogenomes, towards elucidating the phylogeny and evolutionary history of Penaeoidea. All these nine mitogenomes exhibit the pancrustacean ground pattern, except that Benthonectes filipes contains two additional clusters of tRNA^Ala, tRNA^Arg and tRNA^Asn and an uncommon noncoding region. The resulted phylogenetic tree is generally well resolved with Benthesicymidae sister to Aristeidae, forming a clade with Solenoceridae. Contrary to traditional classification, this clade has a sister relationship with the tribe Penaeini of the family Penaeidae. The family Sicyoniidae is deeply nested within the penaeid tribe Trachypenaeini which forms a sister clade with the remaining penaeid tribe, Parapenaeini. As the family Penaeidae is recovered to be polyphyletic, the three tribes in Penaeidae are all elevated to familial status. On the other hand, the family Sicyoniidae is retained to accommodate Trachypenaeini because they are now synonyms and the former name is more senior. This work is the first molecular analysis concurring with the latest findings in fossil assessments showing that Parapeaneini is the most primitive in Penaeoidae. Our results also illustrate a shallow‐water origin and an onshore–offshore evolutionary shift in penaeoid shrimps.     

Histomorphological and endocrine assessment of female Arabian carpetshark,Chiloscyllium arabicum (Elasmobranchii: Hemiscylliidae) from the Persian Gulf during annual reproductive cycle

The present study aimed at assessing the annual reproductive cycle of female Arabian carpetshark, Chiloscyllium arabicum from the Persian Gulf by a macroscopic and microscopic evaluation of the reproductive tract. The annual cycle of gonadal steroids [17β-estradiol (E2), progesterone (P4) and testosterone (T)] was also assessed in this shark. In total, 130 female C. arabicum were collected from the Bahrakan Creek (located northwest of the Persian Gulf) between January 2018 and March 2019. Females were oviparous with an external-type ovary and only one functional ovary. Five sexual maturity stages were recognized based on macroscopic and microscopic evaluation: Immature I (August–October), Immature II (November–January), Mature (February–March), Pregnant (April–May) and Spent (June–July). The structural changes in the oviducts, oviducal glands and uterus throughout the annual reproductive cycle were consistent with their roles in the egg movement, the egg capsule production and sperm storage. The plasma levels of the gonadal steroids were associated with morphological changes in the reproductive tract. E2 showed two detectable peaks during March (close to ovulation) and June (just before mating). P4 and T displayed a peak just before ovulation.     

Reproductive biology of Philodryas patagoniensis (Snakes: Dipsadidae) in south Brazil: Female reproductive cycle

In this study, we describe the female reproductive cycle of Philodryas patagoniensis in south Brazil, which was described through morpho‐anatomical and histological analyses. The peak of secondary vitellogenesis occurred during winter–spring (July–December), ovulation in spring (October–December), mating and fertilization in spring–summer (October–February), oviposition in spring–autumn (October–May) and births from late spring to autumn (December–July). The diameter of vitellogenic follicles/eggs was larger in winter–spring than in other seasons. The diameter of the shell glands was also larger in winter–spring. In spite of the clear reproductive peak, gonads only showed reduced activity in the autumn. Therefore, at the individual level, females have a discontinuous cyclical reproduction; in the populational level, the reproductive cycle is seasonal semisynchronous. We support the hypothesis that P. patagoniensis have the ability to produce multiple clutches with long‐term stored sperm. Sexual dimorphism in body size was evident, and females are significantly larger and heavier than males. Larger females were able to produce follicles and eggs in larger amount and size. The maternal body size was positively related to the reproductive effort and fecundity. To conclude, we deliberated about the proximal and distal causes that influence the reproductive traits and patterns of P. patagoniensis.     

Phylogeny of penaeoid shrimps (Decapoda: Penaeoidea) inferred from nuclear protein-coding genes

Penaeoidea is a diverse group of economically important marine shrimps. Attention to the evolutionary history of the penaeoids has been raised since studies using mitochondrial DNA markers and sperm ultrastructure contradict classification of the penaeoid families based on morphology and hence challenge the long standing taxonomy of this superfamily. In this study, DNA sequences of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium–potassium ATPase α-subunit, were determined from 37 penaeoid genera to reconstruct the evolutionary relationships and to estimate divergence ages of the penaeoid shrimps. Phylogenetic analyses using maximum likelihood and Bayesian approaches strongly support the monophyly of Solenoceridae, Aristeidae and Benthesicymidae, but find Sicyoniidae nested within Penaeidae, making this family paraphyletic. Penaeoidea comprises two lineages: the former three families in one while the latter two in another. The diversification of these lineages may be related to bathymetry. The penaeid-like lineage diversified in the Triassic, earlier than the aristeid-like lineage with an origin in the Jurassic. Taxonomic revisions within Penaeoidea are also proposed for further investigation. Due to the paraphyly of Penaeidae and the high genetic divergence among the three penaeid tribes of Burkenroad [Burkenroad, M.D., 1983. Natural classification of Dendrobranchiata, with a key to recent genera. In: Schram, F.R. (Ed.), Crustacean Issues I. Crustacean Phylogeny. A.A. Balkema, Rotterdam, pp. 279–290], these tribes should be treated as having the same taxonomic rank as Sicyoniidae, while the family ranking of Benthesicymidae has to be re-considered owing to the low genetic divergence between the benthesicymids and the aristeids.     

Reproductive parameters of the Pacific angel shark Squatina californica (Selachii: Squatinidae)

Reproductive characteristics of the Pacific angel shark, Squatina californica, were evaluated from 420 specimens obtained from the artisanal fishery in La Paz Bay, Gulf of California, Mexico. Females (99 cm, 6000 g) were larger than males (95 cm, 5000 g) in terms of both total length (L_T) and body mass (M_T). The overall sex ratio was significantly different from the expected 1:1, suggesting sexual segregation of mature individuals in La Paz Bay. Males had developed reproductive organs and calcified claspers from 72 cm L_T; the median size at maturity (L_T50) was 75·6 cm. In females, only the left ovary was functional and mature ovarian follicles were present from 77 cm L_T; the estimated L_T50 was 77·7 cm. For the 10 gravid females sampled, uterine fecundity was between two and 10 embryos. Mature, non‐gravid females with small and large ovarian follicles appeared simultaneously with gravid females with follicles that did not exceed 1·9 cm diameter.     

Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

Four of the most common species of skate (Rajidae) were studied off eastern Canada to determine if their reproductive characteristics were linked to their population trajectories. The fecundity of the winter skate Leucoraja ocellata , the little skate Leucoraja erinacea , the thorny skate Amblyraja radiata and the smooth skate Malacoraja senta averaged between 41 and 56 egg cases per year for each species. For all species but L. ocellata , males matured at larger sizes and at later ages than females. Theoretical rates of population increase for non-equilibrium populations of L. ocellata ( c . 0·07), M. senta ( c . 0·14) and L. erinacea and A. radiata ( c . 0·20) were low compared to most fishes, indicating that north-west Atlantic skates are intrinsically unproductive, yet are theoretically capable of supporting low-level fisheries. Nevertheless, the results of 36 years of research surveys indicate that the abundance of mature L. ocellata , A. radiata and M. senta all decreased by >90% since 1970, indicating that past fishing mortality (both directed and undirected) has outstripped the net productivity of the skate populations on the eastern Scotian Shelf. The relationship between maximum age ( t _max) and age of maturity ( t _mat) was a better predictor of population growth rate than was body size, with the species exhibiting the highest ratios of t _mat : t _max ( L. ocellata = 0·68, M. senta = 0·66) having the lowest predicted population growth rates. L. ocellata appears to have the lowest productivity and has experienced the greatest population decline, thus raising concerns over its future status.     

Population structure and reproductive period of whitebelly prawn Nematopalaemon schmitti (Holthuis 1950) (Decapoda: Caridea: Palaemonidae) on the southeastern coast of Brazil

The population biology of Nematopalaemon schmitti in the Ubatuba region on the northern coast of the state of São Paulo was characterized through analyses of the length-frequency distribution, sex ratio, reproductive period, and juvenile recruitment. The specimens were caught monthly from January 1998 to December 1999, from a shrimp boat equipped with double-rig trawl nets. A total of 1073 specimens were analyzed, and the sex and carapace length (0.1?mm) of each individual were noted. The analyzed specimens consisted of 152 juveniles, 437 adult males, 296 adult females, and 188 ovigerous females (OFs). The monthly distribution of N. schmitti by size classes revealed a stable population structure, with both juveniles and adults continuously present. This population showed a unimodal distribution; however, bimodality was identified in June 1998 and 1999 for males, and June 1998 and July 1998 and 1999 for females, probably related to recruitment pulses of juveniles. Sexual dimorphism was indicated by the presence of females in the larger size classes, probably because of their growth rate. The proportion between males and females differed from 1?:?1 in certain size classes and seasons of the year (χ ²,?p?<?0.05); in some situations, the females were more abundant than the males, or vice versa. No significant relationship was detected between the seasonal mean temperatures of the bottom water and the percentages of OFs and young, or for the relationship between these two groups (Spearman, p?>?0.05). The continuous presence of OFs and young in the population suggests a pattern of continuous reproduction for N. schmitti in the Ubatuba region.     

Insights of the life history in the porcellanid crab Petrolisthes armatus (Gibbes, 1850) (Crustacea: Anomura: Porcellanidae) from the Southwestern Atlantic coast

Petrolisthes armatus (Gibbes, 1850) life history was evaluated based on growth and reproduction. Specimens were captured at Ubatuba (Brazil), identified, sexed and measured: carapace (CL, length; CW, width), larger cheliped propodus (PL, length; PW, width; and PH, height), and 2th and 5th abdominal somite (AW₂ and AW₅, width). Relative growth was studied using CL as independent variable and its relation with other variables (dependents), to estimate puberty size and morphological maturity. Fecundity was represented by number of eggs vs. body size CL, with a better fit using a power function. Considering the 257 specimens analyzed, males were larger than females, and the overall sex ratio was 1:1, with some differences among size classes. Maturity (puberty size) was revealed by: AW₂ × CL (males: 8.6 mm CL; females: 7.6 mm CL); and AW₅ × CL (7.1 and 7.6 mm CL, respectively). Reproduction was continuous, but more intense in rainy season and recruitment occurring in dry season. Fecundity of this species was 228 ± 163 eggs, with better fit by a power function (R² = 0.72). Maturity size and growth differed when a pristine area (Ubatuba) was compared with a polluted area (São Sebastião), in the same Brazilian area (São Paulo State).     

Reproductive dynamics of the white shrimp Litopenaeus schmitti (Burkenroad 1936) in a beach seine fishery in northeastern Brazil

The aim of the present study was to investigate the reproductive dynamics of the Litopenaeus schmitti through macroscopic and microscopic analyses. Specimens were collected monthly from December 2016 to November 2017 through artisanal beach seine fishery in the municipality of Lucena, state of Paraíba, Brazil. A total of 1710 shrimp were caught and the proportion of males was significantly lower than that of females (43.51% and 56.49%). The ovarian maturation stages were classified as immature, initial development, advanced development, mature and spent. These classification criteria added an additional stage than those previously reported for this species on the Brazilian coast. The proportion of ovarian maturation stages per month suggest a seasonal reproductive cycle that extends from September to June, with no reproductive activity occurring in July and August. The reproductive activity was directly related to the precipitation and salinity in the area of the present study. Mean cephalothorax length at first gonad maturity for females (2.20 cm) was larger than values reported 13 years ago for this species in the same area. This finding may indicate that the prohibition of motorized trawler fishing in the area since 1990 is contributing to the more sustainable exploitation of this resource.     

Reproductive biology of Lactoris fernandeziana (Lactoridaceae)

Lactoris fernandeziana, monotypic in its family, is endemic to the cloud forests of Robinson Crusoe Island. Although there has been considerable study of the relationships of Lactoris, as a rare species and as a putative primitive paleoherb, little is known of its reproductive biology. Knowledge of the latter is essential for effective conservation programs. The species is gynomonoecious. The overall proportion of flowers is ∼1 female:1 hermaphrodite. The inconspicuous semipendulous green flowers, usually in mixed-gender inflorescences, do not produce rewards. Hermaphrodite flowers are herkogamous and protogynous. Pollen grains are shed from the extrorse anthers in permanent dry tetrads. There is a mean of 12879 tetrads per hermaphrodite flower. Both flower types bear an average of ∼18 ovules. The P/O (pollen/ovule) ratios imply facultative or obligate xenogamy, but hand pollinations show that Lactoris is self-compatible. No floral visitors were ever observed, but stigmata of open-pollinated flowers bore tetrads, and 64% of such styles had pollen tubes. Flowers enclosed in large mesh (1 mm) bags bore similar numbers of tetrads and pollen tubes. Thus, we conclude that Lactoris is anemophilous, a syndrome perhaps reflected by the P/O ratio. Low genetic diversity (isozymes and DNA) supports selfing and implies limited distance wind pollen dispersal. The small size of the island, the ± 1000 extant Lactoris plants, coupled with anemophily, self-compatibility, and pendant flower position, have yielded a geitonogamous system with high seed set and low genetic diversity. If inbreeding depression is expressed, it is in seed germination and seedling vigor, for Lactoris is very difficult to cultivate. For this species, effective conservation practices need to focus on habitat preservation and promotion of outcrossing.     

Reproductive ecology of Naididae (Oligochaeta)

Asexual reproduction is employed by species of Naididae during favorable environmental conditions. In species characteristic of aquatic habitats subject to rapid fluctuations in water levels and temperatures most individuals in a population become sexually mature, and there is degeneration of the alimentary tract, a shortened breeding season, and aclitellar formation of cocoons. Cocoon deposition allows a population to survive periods of environmental stress. Sexual reproduction predominates near the edges of ranges where stress conditions are more prevalent. Species that reproduce sexually in spring are intolerant of summer conditions, while those that breed in autumn are intolerant of winter. Species typical of environmentally stable bodies of water usually have a minority of the population mature at any time, an extended breeding season, and the ability to continue feeding while mature; thus, adaptations for survival in unstable habitats are lacking.     

Reproductive biology of the guitarfish Rhinobatos percellens (Chondrichthyes,Rhinobatidae) from the São Paulo Coast,Brazil, western South Atlantic Ocean

The reproductive biology of the guitarfish Rhinobatos percellens was studied from 751 specimens caught by bottom pair trawlers off the coast of São Paulo, Brazil, between c. 24° 00′ S; 45° 15′ W and c. 25° 10′ S; 47° 52′ W, from September 2007 to August 2009. The total length (L_T) and total mass (M_T) relationship for males and females combined was M_T = 1·29E‐06 L_T^3·15 (r = 0·99, n = 751). The mean L_T of sexually mature specimens was 548 mm for males and 583 mm for females. Clasper growth was allometric and showed three distinct phases. Most claspers were calcified in specimens of c. 550 mm L_T. The mean diameter of the largest oocyte was 29·8 mm, the mean ovarian fecundity was seven oocytes and ovulation occurred between August and November. Uterine fecundity ranged from two to 13 embryos (mean of five embryos). Larger females had higher litter sizes and larger embryos; the size‐at‐birth was c. 200 mm L_T. The hepato‐somatic index oscillated seasonally for males and females; the gonado‐somatic index had little variation in males, but varied seasonally in females. The presence of many non‐pregnant adult females and of encapsulated eggs during two consecutive seasons suggests a resting period between gestations and the possibility of diapause.     

Reproductive biology of Palythoa caribaeorum and Protopalythoa valilbilis (Cnidaria, Anthozoa, Zoanthidea) from the southeastern coast of Brazil.

The reproductive biology of Palythoa caribaeorum (Duchassaing & Michelotti 1860) and Protopalythoa variabilis (Duerden 1898) was studied through monthly samples from tagged colonies from June 1996 to June 1997, in Sao Sebastiao channel, S?o Paulo, Brazil (45 degrees 26'W, 23 degrees 50'S). The gametogenesis was similar to that of other zoanthids as shown by histological preparations. Oocyte diameters and maturation stages of testis vesicles were evaluated on squash preparations. Both species showed sequential protogynic hermaphroditism, with high frequency of fertile polyps (83% in P. variabilis and 72% in P. caribaeorun), high frequency of colonies in female sex condition (65.3% of P variabilis and 41.7% of P caribaeorum), and apparently continuous gametogenesis. In P. caribaribaeonrum, egg release was continuous and sperm release took place during half of the analyzed period. In P. variabilis, egg and sperm release occurred in April-May and February-March 1997, respectively.     

Reproductive biology of Bagrus docmak in the Victoria Nile,Uganda

Aspects of the reproductive biology of Bagrus docmak in the Victoria Nile were investigated between November 2005 and October 2006. Macroscopic and histological analysis of the gonads confirmed it as an asynchronous batch spawner which spawns throughout the year with bimodal spawning peaks coinciding with rainfall seasons. The first spawning peak occurred from March to May, the second from September to November. The sex ratio did not significantly deviate from 1:1. Length at sexual maturity was 33.6 cm and 31.6 cm fork length (FL) for females and males, respectively. Batch fecundity ranged from 1 000 eggs in 34 cm FL fish to 43 000 eggs in 79 cm FL fish, and correlated linearly with FL (r = 0.72) and body weight (r = 0.79). Mean relative batch fecundity was 6 eggs g^?1 (SE 2). These results could guide research into the possibility of artificially inducing the fish to spawn, and its subsequent culture.