International Journal of Aquatic Biology (2014) 2(6): 337-345 

ISSN: 2322-5270; P-ISSN: 2383-0956

Journal homepage: www.NPAJournals.com 
© 2014 NPAJournals. All rights reserved 

Original Article 

Description of skeletal structure and cranial myology of Cobitis keyvani  
(Cypriniformes: Cobitidae) 

 
Parya Jalili1, Soheil Eagderi*1, Hamed Mousavi-Sabet 

 
1Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran. 

2Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, P.O. Box 1144, Guilan, Iran. 

 
Article history: 
Received 7 October 2014 

Accepted 11 December 2014 

Available online 2 5 December 

2014 

 Keywords:  
Osteology 

Muscle 

Keyvan’s spined loach 

Caspian Sea basin 

Abstract: Cobitis keyvani is recently described from the sourhern Caspian Sea basin. Limited 
information is available about morphological features of C. keyvani, therefore this study was 

conducted to provide osteological characteristics and cranial myology of this species. For this purpose, 

nine specimens of C. keyvani were collected from the Talar River. The specimens were cleared and 

stained with alizarin red S and alcian blue for osteological examinations. The detailed skeletal 

structure and cranial muscles of C. keyvani were provided. Based on the results, C. keyvani can be 

distinguished from other members of the genus Cobitis by a contact between sphenotic and 

supraoccipital and a contact between pterosphenoid, parasphenoid, prootic and sphenotic in terms of 

osteological features.  
 

Introduction 

The genus Cobitis, a member of family Cobitidae, is 
widespread from northern Africa, throughout Europe 

to eastern Siberia, southeast to Central Vietnam 

(Bohlen and Ráb, 2001; Vasil'eva and Vasil'ev, 

2006; Kottelat and Freyhof, 2007). This genus has 

three valid species in Iran, including Cobitis linea 
(Heckel, 1849), C. faridpaki (Mousavi-Sabet, 
Vasil'eva, Vatandoust and Vasil'ev, 2011) and 

C. keyvani (Mousavi-Sabet, Yerli, Vatandoust, 
Ozeren and Moradkhani, 2012) (Mousavi-Sabet et 

al., 2012). However, C. tenia (Linnaeus, 1758) have 
been reported from Iran including southern Caspian 

Sea basin (Abdoli and Naderi, 2009); there are 

believes that C. taenia is a northern European species 
(Bohlen and Ráb, 2001) and its occurrence in the 

southern Caspian Sea basin is unlikely (see in 

Mousavi-Sabet et al., 2012). 

This genus characterized by an elongated and 

compressed body, erectile spine below the eye, three 

pairs of short barbels, minute scales cover the body, 

                                                           
* Corresponding author: Soheil Eagderi 

E-mail address: soheil.eagderi@ut.ac.ir 

small dorsal and anal fins, caudal fin rounded or 

truncated (Coad, 2014). Males also have bony 

extensions of their pectoral fin rays, known as lamina 

circularis. 

Cobitis keyvani was recently described from Talar 
River (sourhern Caspian Sea basin) (Mousavi-sabet 

et al., 2012). This species is distinguished from 

C. linea by lack of second lamina canestrini at the 
base of the first pectoral fin ray, and from C. 
faridpaki by large, dark and obvious spots along the 
mid-flank (Coad, 2014). Since, limited information 

is available about morphological features of 

C. keyvani, therefore, this study was conducted to 
provide a detailed osteological characteristics and 

cranial myology of this species. The results will 

provide a basis for further phylogenetic study of 

Iranian member of the genus Cobitis using 
osteological and morphological data. 

 

Material and methods 

For osteological examination, nine specimens of 



338 
 

International Journal of Aquatic Biology (2014) 2(6): 337-345 

C. Keyvani (Fig. 1) with mean standard length of 
58.7 ± 0.6 mm (Mean ± SD) were collected from the 

Talar River (in the sourhern Caspian Sea basin, Iran). 

The caught specimens were anaesthetized using 1% 

clove solution and then fixed in 4% buffered 

formalin. For osteological examination, the 

specimens were cleared and stained with alizarin red 

S and Alcian blue according to the protocol of Taylor 

and Van Dyke (1972). Muscle fibers of the dissected 

specimens were stained according to Bock and Shear 

(1972). The stained specimens were studied using a 

stereomicroscope (Leica MC5), and different 

skeletal elements were dissected and scanned by a 

scanner equipped with a glycerol bath (Epson V700). 

The obtained images were drawn using 

CorelDrawX6 software. The terminology of skeletal 

elements follows Rojo (2010) and Sawada (1982) 

and Muscle terminology follows Winterbottom 

(1974). The scale bar of all drawings shows 1 mm. 

 

Result and Discussion 

Osteology of Cobitis keyvani 
Neurocranium: In dorsal view, the posterior part of 
the neurocranium is oval-shaped and its anterior part 

is longer and narrower (Fig. 2). The ethmoid region 

consists of the lateral ethmoid, preethmoid II, 

supraethmoid-ethmoid, kinethmoid and pre-vomer 

(Figs. 2a, b, c). The supraethmoid-ethmoid is blade-

shaped positioning on the middle of the pre-vomer 

and has a relatively deep depression on its anterior 

margin and a rounded and downward projection 

under this depression similar to C. taenia (Vasil’eva, 
1984). The anterior part of the pre-vomer is wide; 

pointed posteriorly and overlaps with the anterior 

part of the parasphenoid. The two narrow 

preethmoid II are positioned at the anterior part of 

the prevomer. The preethmoid II bears two processes 

posteriorly viz. the dorsal and ventral processes; the 
dorsal process is articulated with the anterior part of 

the autopalatine and the ventral one with the anterior 

part of the pre-vomer. The preethmoid also bears a 

latero-external pointed process and an anterior facet 

which articulates with the maxilla. The lateral 

ethmoid is a long bone that has two posterior 

processes and one vertical process anteriorly which 

is connected to the orbitosphenoid (Fig. 2b). The 

lateral ethmoid is moveable and projected from skin. 

A free broad kineethmoid is located between two 

maxillae (Fig. 4a).  

The orbital region is composed of the frontal, 

orbitosphenoid, pterosphenoid, parasphenoid, 

lacrimal and sclerotic bones. The frontals have long 

and narrow anterior part. The frontals are separated 

posteriorly by the fontanle. The orbitosphenoid is 

dorsally connected to the anterior part of the frontal 

and ventrally to the parasphenoid. The pterosphenoid 

is ventrally connected to the parasphenoid and 

dorsally to the posterior part of the frontal. Sawada 

(1982) mentions the pterosphenoid is attached only 

to the parasphenoid in Cobitis, Niwaella, 
Sabajenewia, Lepidocephalus and Acanthopsoides, 
but in C. keyvani this bone meets the sphenotic, 
prootic and parasphenoid. The parasphenoid extends 

from the ethmoid region to the occipital region. The 

middle part of this bone is wide and connected to the 

pterosphenoid. Two lateral processes present in the 

Figure 1. Lateral view of Cobitis keyvani from Talar River. 



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Jalili et al/ Osteology and cranial myology of Cobitis keyvani 

middle part of the parasphenoid directing posteriorly 

(Fig. 2b). The parasphenoid is bifurcate posteriorly 

(Fig. 2b). A long lacrimal bone is situated at the 

anterior part of the lateral ethmoid.  

The otic region comprises of the parietal, epiotic, 

sphenotic, pterotic, and prootic (Fig. 2a, b). The 

parietal is almost square-shaped bone and its 

posterior edge sutured with supraoccipital. The 

sphenotic is trapezoid in shape and ventrally 

connected to the prootic and posteriorly to the 

pterotic. According to Sawada (1982) in the genus 

Cobitis, the contact between the sphenotic and 
supraoccipital is absent; while in C. keyvani, the 
posterodarsal margin of the sphenotic is attached to 

the anterolateral part of supraoccipital (Fig. 2a). 

There is no connection between the sphenotic and 

Figure 2. The neurocranium of Cobitis keyvani. (a) Dorsal, (b) ventral and (c) lateral views. Eo: exoccipital; Bo: basioccipital; Ep: epiotic; Fr: 
frontal; Le: lateral ethmoid; Os: orbitosphenoid; Pa: parietal; Pv: prevomer; Pro: prootic; Ps: parasphenoid; Pt: pterotic; So: supraoccipital; Sp: 

Sphenotic. Eo: exoccipital; Bo: basioccipital; Ep: epioti; Fr: frontal; Fon: fontanel; Pa: parietal; Pts: pterosphenoid; Sec: supraethmoid-ethmoid; 

So: supraoccipital; Sp: Sphenotic. 



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International Journal of Aquatic Biology (2014) 2(6): 337-345 

epiotic (Fig. 2a). The ventral edge of the sphenotic 

forms the anterior facet of the neurocranium for 

articulating to the hyomandibular. The anterior part 

of the prootic is bifurcated which its medial branch 

is covered with the parasphenoid and the lateral 

branch attached to the pterosphenoid and sphenotic. 

This bone also has a large pore in its middle part. The 

pterotic is triangular in shape and enclosed by the 

epiotic, sphenotic and parietal bones. The epiotic is 

oval-shaped and attached to the supraoccipital 

posteriorly.  

The occipital region consists of the supraoccipital, 

exoccipitals and basioccipital. The supraoccipital is 

pentagon in shape, and its anterior part is concaved 

(Fig. 2a, b). This bone is posteriorly connected to the 

exoccipital. The exoccipital froramen is located on 

its dorsal face and two other pores are located on its 

ventral part. A pointed process presents in its 

lateroventral part of the exoccipital. The 

basioccipital possesses two posterior processes, 

which are not fused with each other (Fig. 2b). On the 

lateral part of the neurocranium, two facets present 

for articulating with the hyomandibular. The anterior 

facet is formed by the prootic and sphenotic, the 

posterior one forms by the sphenotic, prootic and 

pterotic bones. 

Suspensorium: The suspensorium consists of the 
hyomandibular, ectopterygoid, endopterygoid, 

metapterygoid, symplectic, quadrate and palatine 

(Fig. 3). The dorsal part of the hyomandibular is 

wider than its ventral part. The anterior rim of the 

hyomandibular is almost triangular in shape, and its 

dorsal margin has a pointed process. Also, a large 

pore presents in its middle part of the 

hyomandibular. The opercular condyle is situated on 

the dorsolateral margin of the hyomandibular. A 

fossa is present on the dorsal part of the quadrate 

(Fig. 3). The symplectic is elongated and narrow and 

located at the posterior part of the quadrate. The 

metapterygoid is a flat bone overlapping the 

endopterygoid anterodorsally and concaved 

ventrally. The endopterygoid is thin and bears an 

anterior facet to articulate with the autopalatine. The 

autopalatine is slightly wide and has an abdominal 

facet which is articulated with the pre-vomer. This 

bone also has two anterior and posterior 

protuberances on its dorsal part which letter one is 

larger (Fig. 3). 

Opercular series: The opercular series includes the 
opercle, preopercle, interopercle and subopercle 

(Fig. 3). The anterodorsal part of the opercle bears a 

process; and the hyomandibular condyle is 

positioned under this process. The anteroventral part 

of the opercle is pointed and overlapped by the 

subopercle. The subopercle has two anterior 

processes; its dorsal process is longer than ventral 

Figure 3. Lateral view of the neurocranium in Cobitis keyvani (left side). Ect: ectopterygoid; End: endopterygoid; Hy: hyomandibulare; Io: 
interopercle; Mp: metapterygoid; Op: opercle; P: palatine; Po: praeopercle; Pre: preethmoid; Q: quadrate; So: subopercle; Sym: symplecic. 



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Jalili et al/ Osteology and cranial myology of Cobitis keyvani 

one. The anterior part of the preopercle is pointed 

and covers the anterior part of the interopercle. The 

medial margin of interopercle is connected to the 

interhyal.  

Jaws: The upper jaw consists of the maxilla and 
premaxilla. The premaxilla is L-shaped and thin and 

its horizontal part is wider than the vertical part. The 

horizontal part of this bone is directed dorsally (Fig. 

4a). The maxilla bears a well-developed mediolateral 

downward process whereas in C. taenia, this process 
is small (Vasil’eva, 1984). This bone has an 

anterodarsal articular, which is connected to the 

preethmoid II. A long process presents in the 

anteroventral part of the maxillae (Fig. 4a).  

The lower jaw is composed of the dentary, 

anguloarticular and retroarticular. The dentary 

possesses an anteroventral process that is wide and 

has the coronoid process in the middle part of its 

dorsal portion. In C. keyvani, the coronomeckelian 
is absent. A short triangular retroarticular is 

positioned at the dorsoventral side of 

anguloarticular. The anguloarticular has a facet 

posteriorly which is articulated with the quadrate. 

Branchial apparatus: The branchial apparatus 
includes five pairs of the ceratobranchial, four pairs 

of the epibranchial, three pairs of the hypobranchial, 

two pairs of the inphrapharyngobranchial and four 

unpaired basibranchial bones (Fig. 5a). The 4th 

basibranchial is small. There is a tooth-like process 

on the ventral surface of fifth ceratobranchial, and on 

its dorsal surface; there is a row of 7 to 9 pharyngeal 

teeth. 

Hyoid arch: The hyoid arch comprises of the paired 

epihyals, hypohyals and ceratohyals, unpaired 

urohyal and basihyal, and three pair of the 

branchiostegal rays (Fig. 5b). The horizontal part of 

the urohyal has two lateral triangular processes and 

its vertical part is blade-shape situating on the dorsal 

part of horizontal portion (Fig. 5b). A small pore 

presents in the ventral margin of the vertical part of 

the urohyal. The basihyal is long with narrow middle 

part positioned between the hypohyals. The 

hypohyal consists of two parts viz. ventral and dorsal 
hypohyals that are connected medially. The anterior 

part of the ceratohyal is connected to the dorsal and 

ventral part of the hypohyals. The first 

branchiostegal ray is connected to the medial part of 

the ceratohyal. The second branchiostegal ray is 

connected to the joint of the ceratohyal and epihyal. 

The 3rd branchiostegal ray is attached to the epihyal. 

The dorsal part of the epihyal is pointed. The 

interhyal is a cylindrical bone positioning on the 

dorsal edge of the epihyal (Fig. 5b). The 

branchiostegal rays extend to the dorsal end of the 

subopercle (Fig. 7). 

Pectoral girdle: The pectoral girdle consists of the 
cleithrum, supracleithrum, coracoid, mesocoracoid, 

scapula, posttemporal and radials (Fig. 5c). The 

cliethrum is L-shaped and has a blade-shape process 

on its posteroventral part. The dorsolateral part of the 

cleithrum is articulated with the ventral part of the 

supracleithrum. The supracleirthrum is long and 

dorsally connected to the posttemporal which 

attaches to the pterotic. The scapula has a large 

foramen in middle part and ventrally connected to 

the coracoid. The mesocoracoid is ventrally 

Figure 4. (a) Internal view of upper jaw and (b) lower jaw in Cobitis keyvani. Aa: Anguloarticular; D: dentary; Ke: kinethmoid; Mx: maxillae; 
Pmx: Premaxillae; Ra: retroarticulare. 



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International Journal of Aquatic Biology (2014) 2(6): 337-345 

connected to the coracoid and dorsally to the scapula 

and cliethrum (Fig. 5c). The pectoral fin bears three 

radials that first one is broader and second one has 

the ventral and dorsal processes. The third radial is 

widest one. The pectoral girdle has one unbranched 

and seven branched rays. In males, the second ray of 

pectoral girdle is broader and forms the lamina 

circularis (Fig. 5c).  

Pelvic girdle: The pelvic girdle includes the paired 
pelvic bones, pelvic splint and radials. The posterior 

part of the pelvic bone is broader and its anterior part 

is bifurcate. Three radials present posterior to the 

pelvic bone. The second radial is the smallest one. 

The two pelvic splint bones are positioned in the 

lateral side of the pelvic bones. The pelvic fin has 

one unbranched and six branched rays (Fig. 5d). 

Axial skeleton: The number of vertebrae is 42. The 

weberian apparatus and swim bladder capsule is 

formed by the four anterior centra (Fig. 6a). Also, 

four pair ossicles, including the tripus, intercalarium, 

scaphium and claustrum present in the weberian 

apparatus. The swim bladder capsule is formed from 

fourth centrum. In the lateral margin of the swim 

bladder capsule, there are two large pores that the 

posterior one is rounded and anterior one oval-

shaped. The two pointed processes present in the 

latero-external portion of the swim bladder capsule. 

There are plentiful small pores on the wall of the 

swim bladder capsule. The cranial and caudal parts 

of vertebral column have 21 centra. In C. keyvani, 
similar to other members of Cobitinae including 

Cobitis taenia taenia, C. taenia striata, C. koreensis, 
Acanthopsoides graciroides and Lepidocephalus 
guntea (Sawada, 1982), the number of cranial 

Figure 5. (a) Dorsal view of branchial apparatus, (b) hyoid arches, (c) medial view of pectoral girdle and (d) pelvic girdle of Cobitis keyvani. Bb: 
basibranchial Bh: basihyal; Ch: ceratohyale; Cb: ceratobranchial; Co: coracoid; Eh: epihyal; Hh: dorsal and ventral hypohyal; Eb: epibranchial; 

Hb: hypobranchial; Ipb: inphrapharyngobranchial; Ih: interhyal; Uh: urohyal; Cl: cleitherum; Lc: lamina circularis; Mco: mesocoracoid; R: radial; 

Sc: scapula; Pb: pelvic bone; Ps: pelvic splint. 



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Jalili et al/ Osteology and cranial myology of Cobitis keyvani 

vertebrae is about equal to those of caudal ones.  

Unpaired fins: The dorsal fin has seven 
pterygiophores, one stay, three unbranched and 

seven branched rays (Fig. 6b). The first 

pterygiophore is the largest one and supports the 

unbranched rays. Four free supraneural bones 

present in the front of the dorsal fin.  

The anal fin possesses three unbranched and five 

branched rays, six pterygiophores and a small stay 

(Fig. 6b). The first and largest pterygiophore 

supports the unbranched rays. 

The skeleton of caudal fin consists of the epural, 

parhypural, pleurostyle, and six hypurals bones (Fig. 

7). In C. keivany, the hyporal-1 is fused with the 
hypural-2 (sometimes the first three hypurals are 

fused). The caudal fin bears 17 branched rays and 

various numbers of the procurrent rays. 

Finally, based on the osteological results, C. keyvani 
can be distinguished from other members of the 

genus Cobitis by a contact between sphenotic and 
supraoccipital and a contact between pterosphenoid, 

parasphenoid, prootic and sphenotic. Other features 

of C. keyvani are similar to other members of this 
genus reported by Vasil’eva (1984) and Sawada 

(1982). 

Myology of Cobitis keyvani 
Muscles of the cheek: The adductor mandibulae of 
C. keyvani comprises of A1, A2 and Aω sections, 
while in the studied cyprinids by Matthes (1963), Aω 

was absent, and the adductor mandibulae comprised 

A1, A2 and A3. In the studied species, the section 

A1 is the largest section of the adductor mandibulae 

and originates musculously from the dorsolateral 

margin of the hyomandibular. This section inserts as 

a wide tendon on the anterior portion of the maxillae. 

But in the studied cyprinids by Matthes (1963), A1 

originates from the preoperculum and quadrate and 

runs forward to insert on the antero-external face of 

the maxillary. The section A2 originates from the 

ventral part of both hyomandibular and anterior rim 

of the preopercle and inserts tendinously onto the 

medial part of the coronoid process of the dentary. 

The posterior fibers of A2 are covered by A1. The 

sections Aω and A1 are attached anteriorly to a 

single tendon. The section Aω inserts on the 

posterodorsal edge of the anguiloarticular (Fig. 8).  

Figure 6. (a) Lateral view of the weberian apparatus and (b) dorsal and anal fins in Cobitis keyvani. Dr, distal radial; Mr, medial radial; Ns, neural 
spine; Pr, proximal radial; Na: neural arch; Nc: neural complex. 

Figure 7. (a) Lateral view of the caudal fin in Cobitis keyvani. E: 
epural; H: hypurals; Ph: parhypurale; Pls: pleurostile. 



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International Journal of Aquatic Biology (2014) 2(6): 337-345 

The adductor arcus palatinii occupies the lateral face 

of the hyomandibular. This muscle originates 

musculously from the ptersphenotic and inserts on 

the medial face of the hyomadibular. In other 

cypriniid fishes, it observes that the adductor arcus 

palatine consists of three parts and arises from the 

prootic and parasphenoid and insert on the inner 

dorsal surfaces of the palatine, pterygoid and 

hyomandibular bones (Matthes, 1963). The levator 

arcus palatini muscle originates musculously from 

the lateromedial margin of the parasphenoid and the 

ventral portion of the ptersphenotic and inserts 

musculously on the anterodorsal rim of the 

metapterygoid and the posterodorsal rim of the 

endopterygoid. The anterior fibers of levator arcus 

palatini is attached to the dorsal part of A2 muscle.  

The levator opeculi muscle is conical in shape and 

originates with muscle fibers from the lateral face of 

the sphenotic. This muscle inserts as a tendon on the 

dorsal part of the opercular prominent process. The 

adductor opeculi originates musculously from the 

sphenotic and posterodorsal edge of the 

hyomandibuar and its fibers insert to the dorsal rim 

of opercle (Fig. 8).  

Ventral muscles of the head: The intermandibularis 
muscle lies between the lower jaws. The protractor 

Figure 8. Lateral view of the head muscles in Cobitis keyvani. A1: subsection of the mandibulae Aw: subsection the adductor mandibulae; A2: 
subsection the adductor mandibulae; AO: adductor operculi; D: dentary; Hy: hyomandibular; LO: levator operculi; Mx: maxillae; Op: opercle; 

Pt: pterotic; So: subopecle; Sp: sphenotic. 

Figure 9. Ventral view of the head muscles in Cobitis keyvani. Ch: ceratohyal; D: dentary; Eh: epihyal; HAD.: hyohyoidei adductors; HIN: 
hyohyoides inferioris; HAB.: hyohyoidei; IMD: intermandibularis; PR.HY.: protractor hyoides; STH: sternohyoideus; Uhy: urohyal. 



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Jalili et al/ Osteology and cranial myology of Cobitis keyvani 

hyoides muscle is anteriorly attached to the medial 

face of the dentary and posteriorly to the ventral face 

of the ceratohyal and epihyal. In the family 

Cyprinidae, the intermandibularis is sometimes 

absent or modified into a protractor hyoidei 

(Matthes, 1963). The hyohyoides inferioris connects 

two side of hyoid arch and its fibers are attached to 

the dorsal face of the hyoid arch similar to other 

cyprinid fishes (Matthes, 1963). The hyohyoideus 

abductor connects the left and right branchiostegal 

rays. The hyohyoidei addauctor has developed 

between the branchiostegal rays. The sternohyoideus 

is a large muscle and bears two bundles which are 

connected together. They originate tendinously from 

the anterior part of the urohyal and connect the hyoid 

arch to the cleithrum.  

 

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