scholarly journals Sexual dimorphism in the electric knifefish, Gymnorhamphichthys rondoni (Rhamphichthyidae: Gymnotiformes)

2019 ◽  
Vol 49 (3) ◽  
pp. 213-220
Author(s):  
Elisa Queiroz GARCIA ◽  
Jansen ZUANON
Keyword(s):  
Sexual Dimorphism ◽  
Body Height ◽  
Principal Component ◽  
The Body ◽  
Vertical Line ◽  
Head Length ◽  
Genital Papilla ◽  
Adult Males ◽  
Dioecious Species ◽  
Males And Females

ABSTRACT Sexual dimorfism refers to morphological differences between males and females of a species. It may be a result of different selection pressures acting on either or both sexes and may occur in any sexually-reproducing dioecious species, including fishes. We analyzed 63 females and 63 adult males of Gymnorhamphichthys rondoni (Gymnotiformes) collected by us or deposited in museum collections. Sex was identified through abdominal dissection. We measured length from snout to posterior end of anal-fin, anal-fin length, distance from anus to anal-fin origin, distance from genital papilla to anal-fin origin, body width at beginning of anal-fin, and head length. Morphometric data submitted to a Principal Component Analysis (PCA) grouped males and females according to variables related to body size (along the first component) and to head length and body height along the second and third components. Females were larger than males, whereas males had proportionally larger heads and higher bodies than females. The urogenital papilla of males and females showed differences in shape, size and relative position on the body. The female papilla was elongated horizontally, larger than that of males, and was located on a vertical line below the eye, while the papilla of the males was vertically elongated and located on a vertical line below the operculum. To our knowledge, this is the first recorded case of sexual dimorphism in a species of Rhamphichthyidae, a condition that is now known in all the currently recognized families of Gymnotiformes.

scholarly journals Rheotaxis Response Based on Sexual Dimorphism in the Green Swordtail Fish, Xiphophorus hellerii

Biota ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 128-139
Author(s):  
Muhammad Irsyad Abiyusfi Ghafari ◽  
Vita Fitrianti
Keyword(s):  
Sexual Dimorphism ◽  
Gravid Female ◽  
Adult Males ◽  
Dioecious Species ◽  
Swordtail Fish ◽  
Xiphophorus Hellerii ◽  
Males And Females ◽  
Morphological Differences ◽  
Gravid Females ◽  
The Individual

Morphological distinctions between males and females of a species are referred to by sexual dimorphism. It may result from various selection pressures affecting either sex or both and may occur in any dioecious species, including Green Swordtail fish, which are sexually reproductive. This study examined the different rheotaxis responses of Xiphophorus hellerii based on different sexes and morphological features. We analyzed ten adult males, ten gravid females, and ten non-gravid females of Xiphophorus helleri collected down the river and transferred into the column. We counted the number of the individual that performed positive rheotaxis (+), negative rheotaxis (-), and indifference response (0). The result showed different rheotaxis responses shown by male, non-gravid female, and gravid female X. hellerii. The highest percentage of positive rheotaxis response (movement against the current) was shown by non-gravid female X. hellerii, reaching up to 89%. Morphological differences between male, non-gravid female, and gravid female X. hellerii appear to affect the orientation and ability of X. hellerii in giving response against current and certainly has an impact on their survival in nature.

Sexual dimorphism in the baiji, Lipotes vexillifer

1992 ◽  
Vol 70 (8) ◽  
pp. 1484-1493 ◽  
Author(s):  
Gao Anli ◽  
Zhou Kaiya
Keyword(s):  
Sexual Dimorphism ◽  
Body Length ◽  
Young Female ◽  
The Body ◽  
Analysis Of Covariance ◽  
Adult Males ◽  
Genital Aperture ◽  
Condylobasal Length ◽  
Males And Females ◽  
Width Measurements

Dimorphism was detected in body length and in skull dimensions of the baiji, Lipotes vexillifer. The age of a sample comprising 22 females and 14 males was estimated. A single-phase Laird growth model was fitted to the body length versus age data for females. Two curves were required for the males, one for those with 4 dentinal growth layer groups (GLGs) and another for those above that age, i.e., with more than 4 GLGs. Males and females have about the same growth rate until they have about 4 GLGs, after which males grow more slowly than females. Sexual dimorphism was also found in 9 external measurements, based on t-tests. Analysis of covariance showed that once the effect of body length was removed, only 1 of the 9 measurements, from the tip of the upper jaw to the genital aperture, differed significantly between males and females. Differences in skull measurements resulted mainly from an early slowdown in the rate of longitudinal growth of the male, before the increase in body length slowed. Females and males could be correctly sexed by discriminant analysis using the body length, condylobasal length, and zygomatic width, and also the condylobasal length, width of the rostrum at the base, and the zygomatic width, except for one young female. Eight skull length measurements were greater in adult females than in adult males after the effect of body length was removed, and five skull width measurements were greater in males when the effect of condylobasal length was removed. Asymmetry in the position of the blowhole and in skew of the skull is pronounced and is independent of body length and sex.

Size-At-Age Variability and Sexual Dimorphism of Morphometric Characteristics in the Late Ontogenesis of the Marsh Frog, Pelophylax Ridibundus (Anura, Ranidae), from Terrytory of Crimea

2019 ◽  
Vol 53 (4) ◽  
pp. 325-334
Author(s):  
V. N. Peskov ◽  
N. A. Petrenko ◽  
V. Yu. Reminnyi
Keyword(s):  
Age Groups ◽  
The Body ◽  
Adult Males ◽  
Morphometric Characteristics ◽  
Morphometric Characters ◽  
Mean Values ◽  
Marsh Frog ◽  
Males And Females ◽  
Size At Age ◽  
Linear Body

Abstract We study size-at-age and sexual variability of morphometric characteristics of the marsh frog. According to the size of the body, males were divided into three size-age groups (juvenis, subadultus, adultus), females — into four groups (juvenis, subadultus, adultus, adultus-I). We found that the chronological age of frogs (skeletochronology) does not always correspond to their biological age (size and proportions of the body). We noted that the semi-adult males are reliably larger than females by mean values of 26 studied morphometric characters. Males and females of “adultus” group do not differ by linear body size, significant differences were found in body proportions (7 characters). For the females of “adultus-I” group, the mean values of 26 characters are significantly larger than for “adultus” males. The results of our study showed that with the age of the marsh frog, the level of exhibition, directionality and structure of morphometric sex differences changes.

scholarly journals Morphometric characters and their relationship in estuarine catfish

1970 ◽  
Vol 6 (2) ◽  
pp. 349-353 ◽  
Author(s):  
M Begum ◽  
Abdullah Al-Mamun ◽  
ML Islam ◽  
MJ Alam
Keyword(s):  
Sexual Dimorphism ◽  
Linear Relationship ◽  
Standard Length ◽  
Head Length ◽  
Pectoral Fin ◽  
Morphometric Characters ◽  
Total Length ◽  
Length Standard ◽  
Eye Diameter ◽  
Males And Females

The morphometric observations were made on total length, standard length, pre-caudal length, head length, eye diameter and depth of body at pectoral fin base of estuarine catfish M. gulio. Males and females showed homogeneity in characters. A linear relationship was found between total length and morphometric characters. Regression of length and weight did not deviate significantly from cube law indicating isometric growth. The fish exhibited sexual dimorphism. Keywords: Morphometric characters; Estuarine catfish; Mystus gulio DOI: 10.3329/jbau.v6i2.4833 J. Bangladesh Agril. Univ. 6(2): 349-353, 2008

scholarly journals The genital and anal papillae of Compsura heterura (Characidae: Cheirodontinae): morphological structure and possible role in insemination

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Antônio Queiroz Lezama ◽  
Luiz R. Malabarba
Keyword(s):  
Life Cycle ◽  
Morphological Structure ◽  
Genital Papilla ◽  
Adult Males ◽  
Males And Females ◽  
Anal Papillae ◽  
Anal Organ ◽  
Tubular Shape ◽  
Female Genital

ABSTRACT The function of the genital and anal papillae for insemination in Compsura heterura is discussed based on the description of their morphologies at different stages of the life cycle and during copulation and spawning. In males and females both the genital and anal papillae are involved in copulation in C. heterura. A pre-anal organ, anterior to the anus and stretched posteriorly, is present in adult males. The openings of the urinary channel and oviduct are separate in females. During copulation, there is an approximation between the female genital and anal papillae which become temporarily juxtaposed, forming a chamber enclosing the opening of the oviduct, which may also function in sperm capture. During spawning, the lateral edges of the female genital papilla are projected anteriorly, acquiring a tubular shape for oviposition.

scholarly journals SEXUAL DIMORPHISM IN PSEUDOPUS APODUS (REPTILIA: SAURIA: ANGUIDAE) FROM THE STEPPE CRIMEA

2018 ◽  
Vol 19 ◽  
pp. 1-21
Author(s):  
Oleg V. Kukushkin ◽  
Igor V. Dovgal
Keyword(s):  
Sexual Dimorphism ◽  
Morphometric Parameters ◽  
The Body ◽  
Body Proportions ◽  
Reliable Determination ◽  
Kerch Peninsula ◽  
The Crimea ◽  
Males And Females ◽  
Almost All

The current paper is focused on sexual dimorphism of a giant glass lizard, or sheltopusik, Pseudopus apodus apodus (Pallas, 1775) from its northernmost populations inhabiting the Crimea. In total, 72 P. apodus individuals (45 males and 27 females) were collected at the Kerch Peninsula during 2013–2017. To estimate the variability, 13 morphometric parameters and 18 indices characterizing the head and body proportions were used. It was found that males and females differed significantly by means of almost all parameters, except the body and tail sizes. Besides that, the differences by 10 ratios characterizing head proportions were revealed as well. However, a reliable determination of the lizard sex using linear sizes and/or ratios values seems to be impossible because of the strong overlap of the variability ranges in both sexes. At the same time, the use of the canonical discriminant analysis by the complex of morphometric parameters and by ratios has shown that the males and females in both datasets are classified correctly basing on the sex with an accuracy approximating 100%. The differences in the allometric growth of males and females partially define the sexual dimorphism of P. apodus on head size and shape. A sex-related differences in the development of at least one pair of parameters (head and snout lengths) were clearly evident, since isometry was established for males, while allometry ‒ for females. Moreover, the systems of correlation between the body and head parts differ in both sexes. Thus, male characterisitics correlate significanly, while the female ones were less toughly connected, and some pairs of parameters did not correlate at all.

A new species of Elachistocleis (Anura; Microhylidae) from the Brazilian Amazon

Zootaxa ◽  
2010 ◽  
Vol 2496 (1) ◽  
pp. 63 ◽  
Author(s):  
LUÍS FELIPE TOLEDO
Keyword(s):  
New Species ◽  
Amazon Basin ◽  
Brazilian Amazon ◽  
The Body ◽  
Adult Males ◽  
Males And Females ◽  
A New Species ◽  
Red Coloration

A new species of Elachistocleis (E. magnus) is described from the Amazon basin, in the municipality of Espigão do Oeste, state of Rondônia, Brazil. It differs from all other species of the genus by the combination of the following characters: i) size larger than 31 mm in adult males, ii) grayish ventral coloration, iii) presence of large post-commissural glands, iv) lack of red coloration in the body, and v) grayish dorsum in preserved individuals. There is dimorphism between males and females in size, structures and coloration. Vocalizations and larvae remain unknown.

scholarly journals The Diet and Sexual Differences of the Caspian Bent-Toed Gecko,Tenuidactylus caspius(Squamata: Gekkonidae), in Northern Iran

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Vida Hojati ◽  
Reza Babaei Savasari
Keyword(s):  
Sexual Dimorphism ◽  
Culex Pipiens ◽  
Tail Length ◽  
Adult Males ◽  
Northern Iran ◽  
Widespread Distribution ◽  
Adult Females ◽  
Significant Difference ◽  
Males And Females ◽  
Prey Items

The Caspian bent-toed gecko,Tenuidactylus caspius, is one of the most common nocturnal lizards of Iran with widespread distribution especially in the northern provinces. This research was done in order to study the diet and sexual dimorphism of this species in Sari County from 5 May to 20 October. During this research, 40 specimens of them including 20 males and 20 females were studied for diet and 140 specimens including 70 adult males and 70 adult females were studied for sexual dimorphism. Prey items identified were insects that belong to 15 species of 8 families and 6 orders. The most common prey items wereCulex pipiensandMusca domestica. There is no significant difference between diets of males and females. Results show that the adult males in addition of having the apparent femoral and preanal pores are heavier than females and have larger body, head, and tail length.

scholarly journals Investigations of Variability of Morphometric Characteristics in Stone Crayfish in Order to Preserve Autochthonous Genome

2020 ◽  
Vol 18 (1-2) ◽  
Author(s):  
Rajko Roljić ◽  
Vera Nikolić ◽  
Nebojša Savić
Keyword(s):  
Sexual Dimorphism ◽  
Carapace Length ◽  
Carapace Width ◽  
Morphological Variability ◽  
The Body ◽  
Morphometric Characteristics ◽  
Baited Traps ◽  
Males And Females ◽  
Austropotamobius Torrentium ◽  
Stone Crayfish

This paper presents the information about morphological variability and sexual dimorphism of the stone crayfish (Austropotamobius torrentium) in the area of Korana River in Mrkonjic Grad. The crayfish were caught by hand made baited traps from October 2018 to May 2019. A total of 46 crayfish were caught, of which 33 males and 13 females. The dimensions of eight morphometric characteristics: body weight (W), body length (TBL), rostrum length (ROL), rostrum width (ROW), claw length (CLL), carapace length (CPL), carapace width (CPW) and abdomen length (ABL), were analyzed, both in males and females. Also, the body condition was determined for all individuales. The measurements results of morphometric characteristics partially matched into the alredy known range of variations. These data presens first ones for the observed area. By using Mann-Whitey U-test, it was noted that there are significant differences between the sexes for W, TBL, CLL, CPL, CPW and ABL. These resuls could be explained by sexual dimorphism of the stone crayfish.

scholarly journals Estimation of Body Height from Head Length among Dental Students of a Dental College

2018 ◽  
Vol 56 (213) ◽  
pp. 861-865 ◽  
Author(s):  
Bipana Manandhar ◽  
Ritee Shrestha
Keyword(s):  
Significant Positive Correlation ◽  
Body Height ◽  
Age Groups ◽  
College Teaching ◽  
Dental Students ◽  
Regression Equation ◽  
The Body ◽  
Head Length ◽  
Body Parts ◽  
Positive Correlation

Introduction: Body height is an important measure of physical identity. Height exhibits a dimensional relationship with various parts of the body. This relationship helps to calculate height from dismembered and mutilated body parts in forensic examinations. As the cranial dimensions are more reliable and precise means of predicting the stature, this study was undertaken to find the relation between head length and height and to derive a regression formula for the estimation of height from head length among dental students. Methods: This descriptive cross-sectional study was conducted among 150 dental students of age group 18-21 years in the Department of Anatomy, Kantipur Dental College Teaching Hospital and Research Center, Basundhara, Kathmandu. The head length was measured with the help of spreading caliper. Height was measured with the help of a standard height measuring instrument. The head length and the height of the students were measured in centimeters. Data obtained were analyzed to find the correlation between head length and height and to derive a regression equation for the estimation of height. Results: A significant positive correlation was observed between head length and height (r=0.734, P<0.001). The regression equation for body height and head length including both sexes and all age groups of dental students was found to be y=12.9+8.45x where x is head length and y is body height. Conclusions: It was observed in the present study that there was a significant positive correlation between height and head length in all the age groups indicating that head length is a reliable indicator in estimation of height.

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