Distribution and reproductive biology of the Electric ray Discopyge tschudii Heckel, 1846 in San Matías Gulf, Northern Patagonia, Argentina

The Electric ray Discopyge tschudii is distributed in the Southwest Atlantic from southern Brazil to southern Argentina and in the Southeast Pacific from Peru to southern Chile. The main threat to this species is fishing. Discopyge tschudii is noncommercial and individuals caught are discarded on board. The present study analyzes the distribution and the morphological and reproductive characteristics of this ray in San Matías Gulf (SMG), Argentina. A total of 1087 individuals were analyzed. The species presented an aggregate distribution, with the main concentrations in the northern and eastern areas of SMG, at depths below 100 m. Males ranged from 9 to 43 cm and females from 11 to 38 cm. The species presented sexual dimorphism. Males were larger and heavier than females and also matured at larger sizes. Size at 50% of maturity was estimated at 30 cm for males and 21 cm for females. A total of 199 embryos were sampled and the proportion of sexes showed no significant differences from the expected 1:1. The number of embryos per female varied from 1 to 12. The most frequent values were 2 and 5. Length at birth was estimated at 82.17 ± 3.87 mm. Based on our findings, we hypothesize that the electric ray D. tschudii completes its reproductive cycle in SMG.

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Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

Neotropical Ichthyology ◽

10.1590/1982-0224-20160022 ◽

2017 ◽

Vol 15 (1) ◽

Cited By ~ 1

Author(s):

María L. Estalles ◽

María R. Perier ◽

Edgardo E. Di Giácomo

Keyword(s):

Sexual Dimorphism ◽

Reproductive Biology ◽

Early Spring ◽

Egg Laying ◽

Reproductive Pattern ◽

Reproductive Parameters ◽

Egg Capsules ◽

Northern Patagonia ◽

Total Length

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

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Reproduction of the water snake Helicops infrataeniatus (Colubridae) in southern Brazil

Amphibia-Reptilia ◽

10.1163/156853805774806205 ◽

2005 ◽

Vol 26 (4) ◽

pp. 527-533 ◽

Cited By ~ 17

Author(s):

Luís Felipe Schmidt de Aguiar ◽

Marcos Di-Bernardo

Keyword(s):

Sexual Dimorphism ◽

Reproductive Cycle ◽

Sexual Maturity ◽

Statistical Difference ◽

Rio Grande ◽

Southern Brazil ◽

Rio Grande Do Sul ◽

Water Snake ◽

Males And Females ◽

Two Peaks

AbstractThe reproductive cycle, sexual maturity, fecundity, and sexual dimorphism of Helicops infrataeniatus Jan, 1865, were inferred from the analysis of 374 preserved specimens (110 males, 140 females) from the eastern Central Depression of Rio Grande do Sul, Brazil. There was no statistical difference between the SVL of newborn males and females, but mature females attained greater length than mature males. The tail of mature individuals was proportionally longer in males than in females. Males matured at a smaller size than females. The reproductive cycle of this species was longer than what is known for oviparous colubrids from subtropical and temperate zones of Brazil. In the studied population, vitellogenesis occurred from September to February. Oviductal embryos were found from September to May. Births took place in September, January, February and March, and occurred in two peaks. Litter size ranged from 5 to 22 offspring. The differences between the number of vitellogenic follicles and embryos, and between embryos and newborns were not significant, thus practically all follicles were generally converted into embryos and embryos into newborns.

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Reproductive biology of weakly electric fish Eigenmannia trilineata López and Castello, 1966 (Teleostei, Sternopygidae)

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132009000300014 ◽

2009 ◽

Vol 52 (3) ◽

pp. 617-628 ◽

Cited By ~ 16

Author(s):

Júlia Giora ◽

Clarice Bernhardt Fialho

Keyword(s):

Sexual Dimorphism ◽

Reproductive Biology ◽

Electric Fish ◽

Abiotic Factors ◽

Reproductive Period ◽

Weakly Electric Fish ◽

Southern Brazil ◽

Water Conductivity ◽

Total Length ◽

Weakly Electric

This study described the reproductive biology of a population of the weakly electric fish Eigenmannia trilineata from southern Brazil, providing the information on the estimation of reproductive period, fecundity, spawning type, first maturation size, and analysis of gonadal morphology and histology of the species, relating these data to alimentary and abiotic characters. The species showed a relatively long reproductive period, a relative fecundity of 0.27 oocytes per mg of total weight and a parcelled spawning type. First maturation size estimated for the females was 80.5 mm and for the males 63.5 mm of total length. Sex ratio did not differ from 1:1 under a X²test (α= 0.01) during all the sampled months. Sexual dimorphism was related to total length, and males had larger total length than females. The abiotic factors photoperiod and water conductivity presented significant correlations with female GSI, while male GSI presented a significant correlation only with photoperiod.

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Reproductive biology of Moenkhausia intermedia (Eigenmann) (Pisces, Characiformes) in Itumbiara Reservoir, Goiás, Brazil

Revista Brasileira de Zoologia ◽

10.1590/s0101-81752004000300015 ◽

2004 ◽

Vol 21 (3) ◽

pp. 519-524 ◽

Cited By ~ 21

Author(s):

Renê Eiji Souza Hojo ◽

Gilmar Bastos Santos ◽

Nilo Bazzoli

Keyword(s):

Sexual Dimorphism ◽

Reproductive Biology ◽

Reproductive Cycle ◽

Standard Length ◽

Gonadosomatic Index ◽

Maturity Stage ◽

Female Predominance

To study the reproductive biology of Moenkhausia intermedia (Eigenmann, 1908) in Itumbiara reservoir, Paranaíba river, Goiás, Brazil, a total of 301 specimens (237 females and 64 males) were captured quaterly from January to December 1993. The gonadosomatic index of females and males were related to morphologic variations of the gonads in different reproductive cycle stages (RCS). Analysis of RCS frequency and variations in the gonadosomatic index showed that M. intermedia reproduces during the whole year with fractional spawning. The smallest standard length at advanced maturity stage was estimated as 6.6 cm for females and 6.0 cm for males. The stomach repletion and coelomic fat indexes of both sexes reached peak values in the rest stage, suggesting that this species probably store energy in this phase and consume its fat reserve during reproduction. In the Itumbiara reservoir there was female predominance (4:1). Males were smaller than females, indicating sexual dimorphism in M. intermedia.

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Reproductive biology of the Neotropical electric fish Brachyhypopomus draco (Teleostei: Hypopomidae) from southern Brazil

Neotropical Ichthyology ◽

10.1590/s1679-62252009000400023 ◽

2009 ◽

Vol 7 (4) ◽

pp. 737-744 ◽

Cited By ~ 11

Author(s):

Andrea B. Schaan ◽

Júlia Giora ◽

Clarice B. Fialho

Keyword(s):

Sexual Dimorphism ◽

Sex Ratio ◽

Reproductive Biology ◽

Water Depth ◽

Electric Fish ◽

Gonadosomatic Index ◽

Reproductive Period ◽

Weakly Electric Fish ◽

Hepatosomatic Index ◽

Southern Brazil

The reproductive biology of a population of the weakly electric fish Brachyhypopomus draco from southern Brazil is described. Information is provided on the establishment of the reproductive period in this species and its relations with environmental and feeding factors, as well as on the absolute and relative fecundities, spawning type, sex ratio and sexual dimorphism. The species exhibits a relatively long reproductive period, a relative fecundity of 0.173 oocytes per mg of female total weight, and fractional spawning. The sex ratio did not differ from 1:1 during all sampled months. Sexual dimorphism related to hypertrophy of the male's distal portion of caudal filament was observed and males grew to greater lengths than females. Male gonadosomatic index (GSI) was significantly related to water depth, oxygen saturation and temperature. Female GSI was significantly related to water depth and hepatosomatic index.

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Reproductive biology and sexual dimorphism of a high-altitude population of the viviparous lizard Phymaturus punae from the Andes in Argentina

Amphibia-Reptilia ◽

10.1163/156853807781374791 ◽

2007 ◽

Vol 28 (3) ◽

pp. 427-432 ◽

Cited By ~ 23

Author(s):

Jorgelina Boretto ◽

Juan Carlos Acosta ◽

José Villavicencio ◽

Graciela Blanco ◽

José Marinero ◽

...

Keyword(s):

Life History ◽

Sexual Dimorphism ◽

High Altitude ◽

Reproductive Biology ◽

Reproductive Cycle ◽

Sexual Maturity ◽

Cold Climates ◽

Pregnant Females ◽

Life History Data ◽

The Andes

AbstractPhymaturus punae is a viviparous lizard endemic to the Provincial Reserve San Guillermo, San Juan (Argentina). We present the first life history data of P. punae, belonging to an interesting genus adapted to cold climates. Females reach sexual maturity at 80.6 mm, and males at 84.4 mm snout-vent length. There is sexual dimorphism represented by larger and more robust males, but females show a wider body and a proportionally greater interlimb length than males. In males, spermatozoa become abundant in both testes and epididymi in mid-summer. Vitellogenic and pregnant females occurred simultaneously in late spring and mid-summer indicating a biennial reproductive cycle.

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Evidencia de diferenciación sexual en la almeja Ameghinomya antiqua de la costa chilena y su proporción de sexos

Revista de biología marina y oceanografía ◽

10.22370/rbmo.2018.53.3.1361 ◽

2019 ◽

Vol 53 (3) ◽

pp. 381

Author(s):

Valentina Prida ◽

Andrea Valenzuela ◽

Marcela P. Astorga

Keyword(s):

Sexual Dimorphism ◽

Sex Ratio ◽

Reproductive Biology ◽

Fishery Management ◽

Sex Ratios ◽

Visual Observation ◽

The Other ◽

Limited Information ◽

Southern Chile ◽

Management Decisions

Ameghinomya antiqua is one of the most exploited bivalves in Chile, however, the limited information available on its reproductive biology does not allow proper fishery management decisions to be made. The presence of sexual dimorphism and the sex ratios for this species were detected by observation of gonads extracted from specimens collected from Carelmapu and Quellón, southern Chile. One group of specimens showed milky-white gonads with oocytes (females) while the other exhibited orange gonads with spermatocytes (males). The sex ratio obtained in Carelmapu was 1:1.1, with 48.5% males and 51.5% females; in Quellón, the sex ratio was 1:1.01, with 49.77% males and 50.23% females. We found that dimorphism can be assessed by rapid visual observation of the gonads. Our study proposes an easier and faster way of identifying gender in Ameghinomya antiqua, allowing proper monitoring.

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Ecology of the snake Atractus paraguayensis (Dipsadidae) in southern Brazil

Zoologia (Curitiba) ◽

10.3897/zoologia.35.e12487 ◽

2018 ◽

Vol 35 ◽

pp. 1-6

Author(s):

Noeli Zanella ◽

Fernanda D'Agostini

Keyword(s):

Body Size ◽

Sexual Dimorphism ◽

Reproductive Biology ◽

Field Data ◽

Late Summer ◽

Conservation Strategies ◽

Southern Brazil ◽

Seasonal Breeding ◽

Scientific Collections ◽

Number Of Individuals

Knowledge of snake ecology is important to support conservation strategies.AtractusparaguayensisWerner, 1924 is a dipsadidae with semi fossorial habits distributed throughout southern Brazil. We analyzed the morphology, seasonality and reproductive biology of this species in a subtropical area in southern Brazil by combining material from scientific collections and field data. We found that females have a larger body size than males and that the reproductive cycle of females is seasonal, with vitellogenesis occurring in the warmer months of the year. Males exhibited no differences in testicle volume throughout the year; however, mating likely occurs in the spring when males are more active. Recruitment of newborns occurs in late summer. The number of individuals collected during the hottest months (September through February) was significantly higher than the number of individuals collected during the colder months. Our results, which reveal sexual dimorphism in the species and seasonal breeding restricted to warm months, contribute important information about this species’ biology.

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