SKELETON

The chapter about the anatomy of the Goodeidae is based on the contribution of Abraham Kobelkowsky to the book Viviparous Fishes from Mari Carmen Uribe and Harry Grier, 2005, New Life Publications (ISBN: 0-9645058-5-1), but structured a bit differently and supplemented by more details. The original title of this paper within the book is: "General Anatomy and Sexual Dimorphism of Goodea atripinnis (Teleostei: Goodeidae)", and may be used as basis for this website with the friendly permission of Mari Carmen Uribe, to who we communicate our thanks. 

This chapter is dealing exclusively with the species Goodea atripinnis, and consequently, not all things described herein can be assigned to other species, especially to the Empetrichthyinae. Nevertheless, many things are universal valid for all species or genera, and therefore this chapter should serve as a brief introduction to the anatomy of this amazing group of fish.

Following A. Kobelkowsky, we divide the chapter into the following subchapters:

1. The Skeleton

2. The Musculature

3. The Digestive System

4. The Urogenital System

5. The Circulatory System

6. The Nervous System and the Sense Organs

7. Sexual Dimorphism in Goodea atripinnis

 

The Skeleton

The skeleton of Goodeid fishes (Goodeidae) can be divided into five bigger units: 

1. The neurocranium sensu lato, bearing the brain and visual, olfactory and auditory organs.

2. An apparatus formed by the bones of the upper and the lower jaw, the bones of the mandibular       suspension and the bones of the opercular series, all of them involved in feeding and breathing. 

3. Paired fins, corresponding to our arms and legs, used mainly in manoeuvering.

4. The vertebral column or spine, including ribs and the caudal fin

5. The unpaired dorsal and anal fin.

 

The neurocranium

The neurocranium sensu lato is composed of two parts, meaning the neurocranium sensu stricto, which is composed of the bones providing direct support and protection to the brain and the visual, olfactory, and auditory organs, and bones that are intimately added to the neurocranium. These additional bones include the frontal, the parasphenoid, the parietal and the prevomer. In Goodea atripinnis, the neurocranium sensu lato is wide and dorsoventrally flattened. 

Again, the major bones of the neurocranium sensu stricto occur in four groups: 

1. The occipital region including the unpaired basioccipital and supraoccipital and the paired exoccipitals and epiotics.

2. The otic region (with prootic, intercalar and pterotic).

3. The suborbital region with only lacrimal and dermosphenotic.

4. The ethmoidal or olfactory region, including the mesethmoid and two lateral ethmoids.

The basioccipital is a median, unpaired bone forming the posterior base of the skull. It is the connection between skull and spine. Anteriorly, the unpaired parasphenoid in a discrete angle forms the roof of the mouth. The basioccipital is upwards attached to two exoccipitals, forming the posterior part of the skull. Dorsally and extending anteriorly, forming the roof of the braincase, the exoccipitals are connected to the unpaired supraoccipital and the paired exoccipitals or epiotics. The supraoccipital crest is divided into two posterior alary processes, receiving the muscles supracarinalis anteriores. Each epiotic develops a posterior fragile alary process receiving part of the musculature epiaxialis. The most prominent bones of the skull are the paired wide and asymmetrical frontals, extending from the supraoccipital anteriorly. Between frontals and epiotics are located two smaller parietals. The frontals are connected anteriorly with a pair of lateral ethmoids and the intermediate cartilaginous mesethmoid. With this olfactory region, the wide and laminar prevomer is connected, that is ventrally attached to the parasphenoid. Two nasals, oval and convex, covering the olfactory region. 

From the suborbital series, only lacrimal (connected with the nasal) and dermosphenotic (joined to the frontal) are present, carrying part of the lateral line system. A pair of pterotics (posteriorly) and sphenotics (anteriorly) connect the dermosphenotic with epiotic and exoccipital. Each pterotic develops a wide shelf that includes the horizontal semicircular canal, and dorsally receives part of the axial musculature. Each sphenotic has a ventral process joining the dermosphenotic. Ventrally, a pair of prootics together with small intercalars complete together with the pterotics the otic region.

 

The jaws, mandibular suspension, hyoid and branchial apparatus

The premaxillae, forming together with two maxillas the upper jaw, have a short ascending process and bear two kind of teeth. The dentary, which has an irregular shape is forming the most anterior part of the lower jaw, and also has got two types of teeth. They are arranged in two rows of marginal bifid teeth, and an ensemble of shorter, conic teeth. The other bones of the lower jaw are articular and angular. The articular has anteriorly an articular fossa, therefore forming the articulation to the quadrate, the first bone from the mandibular suspension. 

The bones of the mandibular suspension are slender; the symplectic is remarkably large whereas the mesopterygoid is short, metapterygoid and ectopterygoid are absent. The hyomandibular, originally part of the second gill arch, connect the lower jaw with the skull. 

Originated from the same second gill arch is the hyoid apparatus. It is composed of five branchiostegals and a group of unpaired, median bones. These branchiostegals support the branchiostegal or gill membrane, that encloses the gill chamber ventrally. The median bones of the hyoid arch are a small interhyal, a slender basihyal, a long and slender urohyal, a ceratohyal, connected to the first four branchistegals and an epihyal, connected to the fifth branchistegal.

The branchial apparatus is formed by 3 slender basibranchials, 3 short hypobranchials, 4 long ceratobranchials, 4 epibranchials, the toothed lower pharyngeal and the 3 toothed pharyngobranchials. The last basibranchial is cartilaginous. The upper and lower pharyngeal teeth are pointed and vary gradually from robust to seriform.

The operculum is composed of two parts. Preopercle and interopercle cover the anterior region of the hyoid arch and parts of the mandibular suspension, opercle and subopercle cover the gill chamber with the branchial apparatus.  

 

The spine and the fins

Functionally, the pectoral girdle may be seen as part of the head, supporting more or less the gill chamber posteriorly. The uppermost boneis a slender and forked posttemporal bone, that has a large superior process. The following supracleithrum is short, and from it originates Baudelots ligament and inserts on the basioccipital. The postcleithrum superior is oval and laminar, whereas the postcleithrum inferior is slender; both postcleithra contact the first pleural rib. Other important bones of the pectoral girdle are cleithrum, scapula and coracoid. Coracoid and scapula are connected by 4 radials (or actinosts) with the rays of the pectoral fin.

The pelvic girdle is represented by two single triangular bones, called pelvic bones, that have overlapping medial processes and carry 7 pelvic fin rays. 

The spine or vertebral column can be divided into three groups of vertebrae. The anterior ones are called precaudal vertebrae, the posterior ones caudal vertebrae and the last part of the spine is formed by the caudal complex. The spine is connected to the basioccipital with the first of 19 or 20 precaudal vertebrae. This first precaudal vertebra has an open neural arch and lacks transverse processes. The remaining ones have wide transverse processes. Vertebrae 2 to 6 develop neural crests, whereas the rest bear neural spines. All except the first precaudal vertebra have got curved, strong pleural ribs on their transverse processes and 12 small and short epipleural ribs, articulating with the the first 11 pleural ribs. The first epipleural rib is corresponding to the first vertebra, but not contacting it. 

The first caudal vertebra has one hemal arch with laminat, lateral processes. The others have spines instead of any processes. 

The caudal complex includes one dorsally lying epural, the urostyle, the wide hypural plate and the ventrally lying parhypural. However, the neural and hemal processes of the last four vertebrae additionally support the caudal rays.

The dorsal fin is composed of 14 (13 in females) dorsal proximal pterygophores or radials, tiny distant radials and 14 (13 in females) dorsal rays; the anal fin by 15 anal proximal pterygophores or radials, tiny distant radials and 15 anal rays. The anal pterygophores are larger in males than in females. The anal fin pterygophore - unit is called andropodial (gonopodial) suspension. The largest male anal proximal pterygophore can be divided into the SL 8 times, but 10.8 times in females. In males, the first anal ray is very small, the following 5 rays are shortened and separated from the remaining 9 or 10 by a notch, forming a structure, called gonopodium or andropodium. In order to distinguish it from the Poeciliid gonopodium, that is marked differently in shape and function, we prefer the term andropodium for this part of the Goodeid reproductive organ.

 

 

 

 

 

1. The neurocranium sensu lato, bearing the brain and visual, olfactory and auditory organs, 
2. An apparatus formed by the bones of the upper and the lower jaw, the bones of the mandibular suspension and the bones of the opercular series, all of them involved in feeding    
    and breathing. 
3. Paired fins, corresponding to our arms and legs, used mainly in manoeuvering.
4. The vertebral column or spine, including ribs and the caudal fin. 
5. The unpaired dorsal and anal fin.
The neurocranium
The neurocranium sensu lato is composed of two parts, meaning the neurocranium sensu stricto, which is composed of the bones providing direct support and protection to the brain and the visual, olfactory, and auditory organs, and bones that are intimately added to the neurocranium. These additional bones include the frontal, the parasphenoid, the parietal and the prevomer. In Goodea atripinnis, the neurocranium sensu lato is wide and dorsoventrally flattened. 
Again, the major bones of the neurocranium sensu stricto occur in four groups: 
1. The occipital region including the unpaired basioccipital and supraoccipital and the paired exoccipitals and epiotics.
2. The otic region (with prootic, intercalar and pterotic).
3. The suborbital region with only lacrimal and dermosphenotic.
4. The ethmoidal or olfactory region, including the mesethmoid and two lateral ethmoids.
The basioccipital is a median, unpaired bone forming the posterior base of the skull. It is the connection between skull and spine. Anteriorly, the unpaired parasphenoid in a discrete angle forms the roof of the mouth. The basioccipital is upwards attached to two exoccipitals, forming the posterior part of the skull. Dorsally and extending anteriorly, forming the roof of the braincase, the exoccipitals are connected to the unpaired supraoccipital and the paired exoccipitals or epiotics. The supraoccipital crest is divided into two posterior alary processes, receiving the muscles supracarinalis anteriores. Each epiotic develops a posterior fragile alary process receiving part of the musculature epiaxialis. The most prominent bones of the skull are the paired wide and asymmetrical frontals, extending from the supraoccipital anteriorly. Between frontals and epiotics are located two smaller parietals. The frontals are connected anteriorly with a pair of lateral ethmoids and the intermediate cartilaginous mesethmoid. With this olfactory region, the wide and laminar prevomer is connected, that is ventrally attached to the parasphenoid. Two nasals, oval and convex, covering the olfactory region. 
From the suborbital series, only lacrimal (connected with the nasal) and dermosphenotic (joined to the frontal) are present, carrying part of the lateral line system. A pair of pterotics (posteriorly) and sphenotics (anteriorly) connect the dermosphenotic with epiotic and exoccipital. Each pterotic develops a wide shelf that includes the horizontal semicircular canal, and dorsally receives part of the axial musculature. Each sphenotic has a ventral process joining the dermosphenotic. Ventrally, a pair of prootics together with small intercalars complete together with the pterotics the otic region.
The jaws, mandibular suspension, hyoid and branchial apparatus
The premaxillae, forming together with two maxillas the upper jaw, have a short ascending process and bear two kind of teeth. The dentary, which has an irregular shape is forming the most anterior part of the lower jaw, and also has got two types of teeth. They are arranged in two rows of marginal bifid teeth, and an ensemble of shorter, conic teeth. The other bones of the lower jaw are articular and angular. The articular has anteriorly an articular fossa, therefore forming the articulation to the quadrate, the first bone from the mandibular suspension. 
The bones of the mandibular suspension are slender; the symplectic is remarkably large whereas the mesopterygoid is short, metapterygoid and ectopterygoid are absent. The hyomandibular, originally part of the second gill arch, connect the lower jaw with the skull. 
Originated from the same second gill arch is the hyoid apparatus. It is composed of five branchiostegals and a group of unpaired, median bones. These branchiostegals support the branchiostegal or gill membrane, that encloses the gill chamber ventrally. The median bones of the hyoid arch are a small interhyal, a slender basihyal, a long and slender urohyal, a ceratohyal, connected to the first four branchistegals and an epihyal, connected to the fifth branchistegal.
The branchial apparatus is formed by 3 slender basibranchials, 3 short hypobranchials, 4 long ceratobranchials, 4 epibranchials, the toothed lower pharyngeal and the 3 toothed pharyngobranchials. The last basibranchial is cartilaginous. The upper and lower pharyngeal teeth are pointed and vary gradually from robust to seriform.
The operculum is composed of two parts. Preopercle and interopercle cover the anterior region of the hyoid arch and parts of the mandibular suspension, opercle and subopercle cover the gill chamber with the branchial apparatus.  
The spine and the fins
Functionally, the pectoral girdle may be seen as part of the head, supporting more or less the gill chamber posteriorly. The uppermost boneis a slender and forked posttemporal bone, that has a large superior process. The following supracleithrum is short, and from it originates Baudelots ligament and inserts on the basioccipital. The postcleithrum superior is oval and laminar, whereas the postcleithrum inferior is slender; both postcleithra contact the first pleural rib. Other important bones of the pectoral girdle are cleithrum, scapula and coracoid. Coracoid and scapula are connected by 4 radials (or actinosts) with the rays of the pectoral fin.
The pelvic girdle is represented by two single triangular bones, called pelvic bones, that have overlapping medial processes and carry 7 pelvic fin rays. 
The spine or vertebral column can be divided into three groups of vertebrae. The anterior ones are called precaudal vertebrae, the posterior ones caudal vertebrae and the last part of the spine is formed by the caudal complex. The spine is connected to the basioccipital with the first of 19 or 20 precaudal vertebrae. This first precaudal vertebra has an open neural arch and lacks transverse processes. The remaining ones have wide transverse processes. Vertebrae 2 to 6 develop neural crests, whereas the rest bear neural spines. All except the first precaudal vertebra have got curved, strong pleural ribs on their transverse processes and 12 small and short epipleural ribs, articulating with the the first 11 pleural ribs. The first epipleural rib is corresponding to the first vertebra, but not contacting it. 
The first caudal vertebra has one hemal arch with laminat, lateral processes. The others have spines instead of any processes. 
The caudal complex includes one dorsally lying epural, the urostyle, the wide hypural plate and the ventrally lying parhypural. However, the neural and hemal processes of the last four vertebrae additionally support the caudal rays.
The dorsal fin is composed of 14 dorsal proximal pterygophores or radials, tiny distant radials and 14 dorsal rays; the anal fin by 15 anal proximal pterygophores or radials, tiny distant radials and 15 anal rays. The anal pterygophores are larger in males than in females. The anal fin pterygophore - unit is called andropodial (gonopodial) suspension. The largest male anal proximal pterygophore can be divided into the SL 8 times, but 10.8 times in females. In males, the first anal ray is very small, the following 5 rays are shortened and separated from the remaining 9 or 10 by a notch, forming a structure, called gonopodium or andropodium. In order to distinguish it from the Poeciliid gonopodium, that is marked different in shape and function, we prefer the term andropodium for this part of the Goodeid reproductive organ.
skeleton of Goodeid fishes (Goodeidae) can be divided into five bigger units: 
1. The neurocranium sensu lato, bearing the brain and visual, olfactory and auditory organs, 
2. An apparatus formed by the bones of the upper and the lower jaw, the bones of the mandibular suspension and the bones of the opercular series, all of them involved in feeding    
    and breathing. 
3. Paired fins, corresponding to our arms and legs, used mainly in manoeuvering.
4. The vertebral column or spine, including ribs and the caudal fin. 
5. The unpaired dorsal and anal fin.
The neurocranium
The neurocranium sensu lato is composed of two parts, meaning the neurocranium sensu stricto, which is composed of the bones providing direct support and protection to the brain and the visual, olfactory, and auditory organs, and bones that are intimately added to the neurocranium. These additional bones include the frontal, the parasphenoid, the parietal and the prevomer. In Goodea atripinnis, the neurocranium sensu lato is wide and dorsoventrally flattened. 
Again, the major bones of the neurocranium sensu stricto occur in four groups: 
1. The occipital region including the unpaired basioccipital and supraoccipital and the paired exoccipitals and epiotics.
2. The otic region (with prootic, intercalar and pterotic).
3. The suborbital region with only lacrimal and dermosphenotic.
4. The ethmoidal or olfactory region, including the mesethmoid and two lateral ethmoids.
The basioccipital is a median, unpaired bone forming the posterior base of the skull. It is the connection between skull and spine. Anteriorly, the unpaired parasphenoid in a discrete angle forms the roof of the mouth. The basioccipital is upwards attached to two exoccipitals, forming the posterior part of the skull. Dorsally and extending anteriorly, forming the roof of the braincase, the exoccipitals are connected to the unpaired supraoccipital and the paired exoccipitals or epiotics. The supraoccipital crest is divided into two posterior alary processes, receiving the muscles supracarinalis anteriores. Each epiotic develops a posterior fragile alary process receiving part of the musculature epiaxialis. The most prominent bones of the skull are the paired wide and asymmetrical frontals, extending from the supraoccipital anteriorly. Between frontals and epiotics are located two smaller parietals. The frontals are connected anteriorly with a pair of lateral ethmoids and the intermediate cartilaginous mesethmoid. With this olfactory region, the wide and laminar prevomer is connected, that is ventrally attached to the parasphenoid. Two nasals, oval and convex, covering the olfactory region. 
From the suborbital series, only lacrimal (connected with the nasal) and dermosphenotic (joined to the frontal) are present, carrying part of the lateral line system. A pair of pterotics (posteriorly) and sphenotics (anteriorly) connect the dermosphenotic with epiotic and exoccipital. Each pterotic develops a wide shelf that includes the horizontal semicircular canal, and dorsally receives part of the axial musculature. Each sphenotic has a ventral process joining the dermosphenotic. Ventrally, a pair of prootics together with small intercalars complete together with the pterotics the otic region.
The jaws, mandibular suspension, hyoid and branchial apparatus
The premaxillae, forming together with two maxillas the upper jaw, have a short ascending process and bear two kind of teeth. The dentary, which has an irregular shape is forming the most anterior part of the lower jaw, and also has got two types of teeth. They are arranged in two rows of marginal bifid teeth, and an ensemble of shorter, conic teeth. The other bones of the lower jaw are articular and angular. The articular has anteriorly an articular fossa, therefore forming the articulation to the quadrate, the first bone from the mandibular suspension. 
The bones of the mandibular suspension are slender; the symplectic is remarkably large whereas the mesopterygoid is short, metapterygoid and ectopterygoid are absent. The hyomandibular, originally part of the second gill arch, connect the lower jaw with the skull. 
Originated from the same second gill arch is the hyoid apparatus. It is composed of five branchiostegals and a group of unpaired, median bones. These branchiostegals support the branchiostegal or gill membrane, that encloses the gill chamber ventrally. The median bones of the hyoid arch are a small interhyal, a slender basihyal, a long and slender urohyal, a ceratohyal, connected to the first four branchistegals and an epihyal, connected to the fifth branchistegal.
The branchial apparatus is formed by 3 slender basibranchials, 3 short hypobranchials, 4 long ceratobranchials, 4 epibranchials, the toothed lower pharyngeal and the 3 toothed pharyngobranchials. The last basibranchial is cartilaginous. The upper and lower pharyngeal teeth are pointed and vary gradually from robust to seriform.
The operculum is composed of two parts. Preopercle and interopercle cover the anterior region of the hyoid arch and parts of the mandibular suspension, opercle and subopercle cover the gill chamber with the branchial apparatus.  
The spine and the fins
Functionally, the pectoral girdle may be seen as part of the head, supporting more or less the gill chamber posteriorly. The uppermost boneis a slender and forked posttemporal bone, that has a large superior process. The following supracleithrum is short, and from it originates Baudelots ligament and inserts on the basioccipital. The postcleithrum superior is oval and laminar, whereas the postcleithrum inferior is slender; both postcleithra contact the first pleural rib. Other important bones of the pectoral girdle are cleithrum, scapula and coracoid. Coracoid and scapula are connected by 4 radials (or actinosts) with the rays of the pectoral fin.
The pelvic girdle is represented by two single triangular bones, called pelvic bones, that have overlapping medial processes and carry 7 pelvic fin rays. 
The spine or vertebral column can be divided into three groups of vertebrae. The anterior ones are called precaudal vertebrae, the posterior ones caudal vertebrae and the last part of the spine is formed by the caudal complex. The spine is connected to the basioccipital with the first of 19 or 20 precaudal vertebrae. This first precaudal vertebra has an open neural arch and lacks transverse processes. The remaining ones have wide transverse processes. Vertebrae 2 to 6 develop neural crests, whereas the rest bear neural spines. All except the first precaudal vertebra have got curved, strong pleural ribs on their transverse processes and 12 small and short epipleural ribs, articulating with the the first 11 pleural ribs. The first epipleural rib is corresponding to the first vertebra, but not contacting it. 
The first caudal vertebra has one hemal arch with laminat, lateral processes. The others have spines instead of any processes. 
The caudal complex includes one dorsally lying epural, the urostyle, the wide hypural plate and the ventrally lying parhypural. However, the neural and hemal processes of the last four vertebrae additionally support the caudal rays.
The dorsal fin is composed of 14 dorsal proximal pterygophores or radials, tiny distant radials and 14 dorsal rays; the anal fin by 15 anal proximal pterygophores or radials, tiny distant radials and 15 anal rays. The anal pterygophores are larger in males than in females. The anal fin pterygophore - unit is called andropodial (gonopodial) suspension. The largest male anal proximal pterygophore can be divided into the SL 8 times, but 10.8 times in females. In males, the first anal ray is very small, the following 5 rays are shortened and separated from the remaining 9 or 10 by a notch, forming a structure, called gonopodium or andropodium. In order to distinguish it from the Poeciliid gonopodium, that is marked different in shape and function, we prefer the term andropodium for this part of the Goodeid reproductive organThe skeleton of Goodeid fishes (Goodeidae) can be divided into five bigger units: 
1. The neurocranium sensu lato, bearing the brain and visual, olfactory and auditory organs, 
2. An apparatus formed by the bones of the upper and the lower jaw, the bones of the mandibular suspension and the bones of the opercular series, all of them involved in feeding    
    and breathing. 
3. Paired fins, corresponding to our arms and legs, used mainly in manoeuvering.
4. The vertebral column or spine, including ribs and the caudal fin. 
5. The unpaired dorsal and anal fin.
The neurocranium
The neurocranium sensu lato is composed of two parts, meaning the neurocranium sensu stricto, which is composed of the bones providing direct support and protection to the brain and the visual, olfactory, and auditory organs, and bones that are intimately added to the neurocranium. These additional bones include the frontal, the parasphenoid, the parietal and the prevomer. In Goodea atripinnis, the neurocranium sensu lato is wide and dorsoventrally flattened. 
Again, the major bones of the neurocranium sensu stricto occur in four groups: 
1. The occipital region including the unpaired basioccipital and supraoccipital and the paired exoccipitals and epiotics.
2. The otic region (with prootic, intercalar and pterotic).
3. The suborbital region with only lacrimal and dermosphenotic.
4. The ethmoidal or olfactory region, including the mesethmoid and two lateral ethmoids.
The basioccipital is a median, unpaired bone forming the posterior base of the skull. It is the connection between skull and spine. Anteriorly, the unpaired parasphenoid in a discrete angle forms the roof of the mouth. The basioccipital is upwards attached to two exoccipitals, forming the posterior part of the skull. Dorsally and extending anteriorly, forming the roof of the braincase, the exoccipitals are connected to the unpaired supraoccipital and the paired exoccipitals or epiotics. The supraoccipital crest is divided into two posterior alary processes, receiving the muscles supracarinalis anteriores. Each epiotic develops a posterior fragile alary process receiving part of the musculature epiaxialis. The most prominent bones of the skull are the paired wide and asymmetrical frontals, extending from the supraoccipital anteriorly. Between frontals and epiotics are located two smaller parietals. The frontals are connected anteriorly with a pair of lateral ethmoids and the intermediate cartilaginous mesethmoid. With this olfactory region, the wide and laminar prevomer is connected, that is ventrally attached to the parasphenoid. Two nasals, oval and convex, covering the olfactory region. 
From the suborbital series, only lacrimal (connected with the nasal) and dermosphenotic (joined to the frontal) are present, carrying part of the lateral line system. A pair of pterotics (posteriorly) and sphenotics (anteriorly) connect the dermosphenotic with epiotic and exoccipital. Each pterotic develops a wide shelf that includes the horizontal semicircular canal, and dorsally receives part of the axial musculature. Each sphenotic has a ventral process joining the dermosphenotic. Ventrally, a pair of prootics together with small intercalars complete together with the pterotics the otic region.
The jaws, mandibular suspension, hyoid and branchial apparatus
The premaxillae, forming together with two maxillas the upper jaw, have a short ascending process and bear two kind of teeth. The dentary, which has an irregular shape is forming the most anterior part of the lower jaw, and also has got two types of teeth. They are arranged in two rows of marginal bifid teeth, and an ensemble of shorter, conic teeth. The other bones of the lower jaw are articular and angular. The articular has anteriorly an articular fossa, therefore forming the articulation to the quadrate, the first bone from the mandibular suspension. 
The bones of the mandibular suspension are slender; the symplectic is remarkably large whereas the mesopterygoid is short, metapterygoid and ectopterygoid are absent. The hyomandibular, originally part of the second gill arch, connect the lower jaw with the skull. 
Originated from the same second gill arch is the hyoid apparatus. It is composed of five branchiostegals and a group of unpaired, median bones. These branchiostegals support the branchiostegal or gill membrane, that encloses the gill chamber ventrally. The median bones of the hyoid arch are a small interhyal, a slender basihyal, a long and slender urohyal, a ceratohyal, connected to the first four branchistegals and an epihyal, connected to the fifth branchistegal.
The branchial apparatus is formed by 3 slender basibranchials, 3 short hypobranchials, 4 long ceratobranchials, 4 epibranchials, the toothed lower pharyngeal and the 3 toothed pharyngobranchials. The last basibranchial is cartilaginous. The upper and lower pharyngeal teeth are pointed and vary gradually from robust to seriform.
The operculum is composed of two parts. Preopercle and interopercle cover the anterior region of the hyoid arch and parts of the mandibular suspension, opercle and subopercle cover the gill chamber with the branchial apparatus.  
The spine and the fins
Functionally, the pectoral girdle may be seen as part of the head, supporting more or less the gill chamber posteriorly. The uppermost boneis a slender and forked posttemporal bone, that has a large superior process. The following supracleithrum is short, and from it originates Baudelots ligament and inserts on the basioccipital. The postcleithrum superior is oval and laminar, whereas the postcleithrum inferior is slender; both postcleithra contact the first pleural rib. Other important bones of the pectoral girdle are cleithrum, scapula and coracoid. Coracoid and scapula are connected by 4 radials (or actinosts) with the rays of the pectoral fin.
The pelvic girdle is represented by two single triangular bones, called pelvic bones, that have overlapping medial processes and carry 7 pelvic fin rays. 
The spine or vertebral column can be divided into three groups of vertebrae. The anterior ones are called precaudal vertebrae, the posterior ones caudal vertebrae and the last part of the spine is formed by the caudal complex. The spine is connected to the basioccipital with the first of 19 or 20 precaudal vertebrae. This first precaudal vertebra has an open neural arch and lacks transverse processes. The remaining ones have wide transverse processes. Vertebrae 2 to 6 develop neural crests, whereas the rest bear neural spines. All except the first precaudal vertebra have got curved, strong pleural ribs on their transverse processes and 12 small and short epipleural ribs, articulating with the the first 11 pleural ribs. The first epipleural rib is corresponding to the first vertebra, but not contacting it. 
The first caudal vertebra has one hemal arch with laminat, lateral processes. The others have spines instead of any processes. 
The caudal complex includes one dorsally lying epural, the urostyle, the wide hypural plate and the ventrally lying parhypural. However, the neural and hemal processes of the last four vertebrae additionally support the caudal rays.
The dorsal fin is composed of 14 dorsal proximal pterygophores or radials, tiny distant radials and 14 dorsal rays; the anal fin by 15 anal proximal pterygophores or radials, tiny distant radials and 15 anal rays. The anal pterygophores are larger in males than in females. The anal fin pterygophore - unit is called andropodial (gonopodial) suspension. The largest male anal proximal pterygophore can be divided into the SL 8 times, but 10.8 times in females. In males, the first anal ray is very small, the following 5 rays are shortened and separated from the remaining 9 or 10 by a notch, forming a structure, called gonopodium or andropodium. In order to distinguish it from the Poeciliid gonopodium, that is marked different in shape and function, we prefer the term andropodium for this part of the Goodeid reproductive organ.The skeleton of Goodeid fishes (Goodeidae) can be divided into five bigger units: 
1. The neurocranium sensu lato, bearing the brain and visual, olfactory and auditory organs, 
2. An apparatus formed by the bones of the upper and the lower jaw, the bones of the mandibular suspension and the bones of the opercular series, all of them involved in feeding    
    and breathing. 
3. Paired fins, corresponding to our arms and legs, used mainly in manoeuvering.
4. The vertebral column or spine, including ribs and the caudal fin. 
5. The unpaired dorsal and anal fin.
The neurocranium
The neurocranium sensu lato is composed of two parts, meaning the neurocranium sensu stricto, which is composed of the bones providing direct support and protection to the brain and the visual, olfactory, and auditory organs, and bones that are intimately added to the neurocranium. These additional bones include the frontal, the parasphenoid, the parietal and the prevomer. In Goodea atripinnis, the neurocranium sensu lato is wide and dorsoventrally flattened. 
Again, the major bones of the neurocranium sensu stricto occur in four groups: 
1. The occipital region including the unpaired basioccipital and supraoccipital and the paired exoccipitals and epiotics.
2. The otic region (with prootic, intercalar and pterotic).
3. The suborbital region with only lacrimal and dermosphenotic.
4. The ethmoidal or olfactory region, including the mesethmoid and two lateral ethmoids.
The basioccipital is a median, unpaired bone forming the posterior base of the skull. It is the connection between skull and spine. Anteriorly, the unpaired parasphenoid in a discrete angle forms the roof of the mouth. The basioccipital is upwards attached to two exoccipitals, forming the posterior part of the skull. Dorsally and extending anteriorly, forming the roof of the braincase, the exoccipitals are connected to the unpaired supraoccipital and the paired exoccipitals or epiotics. The supraoccipital crest is divided into two posterior alary processes, receiving the muscles supracarinalis anteriores. Each epiotic develops a posterior fragile alary process receiving part of the musculature epiaxialis. The most prominent bones of the skull are the paired wide and asymmetrical frontals, extending from the supraoccipital anteriorly. Between frontals and epiotics are located two smaller parietals. The frontals are connected anteriorly with a pair of lateral ethmoids and the intermediate cartilaginous mesethmoid. With this olfactory region, the wide and laminar prevomer is connected, that is ventrally attached to the parasphenoid. Two nasals, oval and convex, covering the olfactory region. 
From the suborbital series, only lacrimal (connected with the nasal) and dermosphenotic (joined to the frontal) are present, carrying part of the lateral line system. A pair of pterotics (posteriorly) and sphenotics (anteriorly) connect the dermosphenotic with epiotic and exoccipital. Each pterotic develops a wide shelf that includes the horizontal semicircular canal, and dorsally receives part of the axial musculature. Each sphenotic has a ventral process joining the dermosphenotic. Ventrally, a pair of prootics together with small intercalars complete together with the pterotics the otic region.
The jaws, mandibular suspension, hyoid and branchial apparatus
The premaxillae, forming together with two maxillas the upper jaw, have a short ascending process and bear two kind of teeth. The dentary, which has an irregular shape is forming the most anterior part of the lower jaw, and also has got two types of teeth. They are arranged in two rows of marginal bifid teeth, and an ensemble of shorter, conic teeth. The other bones of the lower jaw are articular and angular. The articular has anteriorly an articular fossa, therefore forming the articulation to the quadrate, the first bone from the mandibular suspension. 
The bones of the mandibular suspension are slender; the symplectic is remarkably large whereas the mesopterygoid is short, metapterygoid and ectopterygoid are absent. The hyomandibular, originally part of the second gill arch, connect the lower jaw with the skull. 
Originated from the same second gill arch is the hyoid apparatus. It is composed of five branchiostegals and a group of unpaired, median bones. These branchiostegals support the branchiostegal or gill membrane, that encloses the gill chamber ventrally. The median bones of the hyoid arch are a small interhyal, a slender basihyal, a long and slender urohyal, a ceratohyal, connected to the first four branchistegals and an epihyal, connected to the fifth branchistegal.
The branchial apparatus is formed by 3 slender basibranchials, 3 short hypobranchials, 4 long ceratobranchials, 4 epibranchials, the toothed lower pharyngeal and the 3 toothed pharyngobranchials. The last basibranchial is cartilaginous. The upper and lower pharyngeal teeth are pointed and vary gradually from robust to seriform.
The operculum is composed of two parts. Preopercle and interopercle cover the anterior region of the hyoid arch and parts of the mandibular suspension, opercle and subopercle cover the gill chamber with the branchial apparatus.  
The spine and the fins
Functionally, the pectoral girdle may be seen as part of the head, supporting more or less the gill chamber posteriorly. The uppermost boneis a slender and forked posttemporal bone, that has a large superior process. The following supracleithrum is short, and from it originates Baudelots ligament and inserts on the basioccipital. The postcleithrum superior is oval and laminar, whereas the postcleithrum inferior is slender; both postcleithra contact the first pleural rib. Other important bones of the pectoral girdle are cleithrum, scapula and coracoid. Coracoid and scapula are connected by 4 radials (or actinosts) with the rays of the pectoral fin.
The pelvic girdle is represented by two single triangular bones, called pelvic bones, that have overlapping medial processes and carry 7 pelvic fin rays. 
The spine or vertebral column can be divided into three groups of vertebrae. The anterior ones are called precaudal vertebrae, the posterior ones caudal vertebrae and the last part of the spine is formed by the caudal complex. The spine is connected to the basioccipital with the first of 19 or 20 precaudal vertebrae. This first precaudal vertebra has an open neural arch and lacks transverse processes. The remaining ones have wide transverse processes. Vertebrae 2 to 6 develop neural crests, whereas the rest bear neural spines. All except the first precaudal vertebra have got curved, strong pleural ribs on their transverse processes and 12 small and short epipleural ribs, articulating with the the first 11 pleural ribs. The first epipleural rib is corresponding to the first vertebra, but not contacting it. 
The first caudal vertebra has one hemal arch with laminat, lateral processes. The others have spines instead of any processes. 
The caudal complex includes one dorsally lying epural, the urostyle, the wide hypural plate and the ventrally lying parhypural. However, the neural and hemal processes of the last four vertebrae additionally support the caudal rays.
The dorsal fin is composed of 14 dorsal proximal pterygophores or radials, tiny distant radials and 14 dorsal rays; the anal fin by 15 anal proximal pterygophores or radials, tiny distant radials and 15 anal rays. The anal pterygophores are larger in males than in females. The anal fin pterygophore - unit is called andropodial (gonopodial) suspension. The largest male anal proximal pterygophore can be divided into the SL 8 times, but 10.8 times in females. In males, the first anal ray is very small, the following 5 rays are shortened and separated from the remaining 9 or 10 by a notch, forming a structure, called gonopodium or andropodium. In order to distinguish it from the Poeciliid gonopodium, that is marked different in shape and function, we prefer the term andropodium for this part of the Goodeid reproductive organ.