the hair samples were obtained from stuffed specimens in the national institute of 
 environmental research ( nier ) and from road kill species collected country - wide by the 
 conservation genome resource bank for korean wildlife ( cgrb ) at seoul national university in 
 korea .
we studied the hair structure of 23 species representing 6 orders , 13 families and 21 
 genera of wild ( n=22 : eothenomys regulus , apodemus 
 agrarius , apodemus peninsulae , rattus 
 norvegicus , sciurus vulgaris , pteromys volans , 
 tamias sibiricus , lepus coreanus , nyctereutes 
 procyonoides , mustela sibirica , lutra lutra , 
 martes flavigula , prionailurus bengalensis , 
 hydropotes inermis , capreolus pygargus , moschus 
 moschiferus , nemorhaedus caudatus , sus scrofa , 
 crocidura lasiura , crocidura sauveolens , mogera 
 robusta and pipistrellus abramus ) and domestic ( n=1 : bos 
 taurus coreanae ) terrestrial mammals , all found in south korea ( table 1table 1.macroscopic characters of korean mammal hair ) .
six of 22 wild species collected are classified as endangered : 
 pteromys volans , lutra lutra , martes 
 flavigula , prionailurus bengalensis , moschus 
 moschiferus and nemorhaedus caudatus .
guard hairs are 
 important in species identification as they exhibit diagnostically reliable features [ 4 , 17 ] .
hair 
 samples were washed in water containing a detergent rinsed sequentially in water , distilled 
 water and stored in 70% alcohol , according to teerink .
dorsal guard hairs ( five hairs from each individual ) were mounted on glass slides with 
 double - sided sticky tape and measured at the hair shaft and shield using a light microscope 
 ( cx31 , olympus , tokyo , japan ) equipped with 10 and 4 lenses for medulla structures .
to 
 analyze the cuticular scales ( hair shaft region ) , which can have many variations [ 14 , 17 ] , we used 
 the sem ( tm-1000 , hitach , tokyo , japan ) .
medulla structures and cuticular scales were classified according to terminology in teerink 
 . net - shape , zipper - shape , columnar and mesh 
 are new terms that we present to describe the morphological characteristics of the hair 
 medulla structures in this study .
the macroscopic view for hair profiles : the macroscopic observation of the 
 guard hair is the first step for hair identification .
the hair of the 
 sus scrofa can be easily identified by general appearance and was quite 
 thick and split ended ( table 1 ) .
the general 
 appearance of cervidae and moschidae hair was uniquely wavy , and that of insectivora was 
 zigzagged ( table 1 ) .
the hair of cervidae , 
 moschidae and insectivora was classified to family and order levels by general appearance ; 
 however , we were not able to identify the hair to species level .
it was difficult to identify by color . thus , microscopic inspection was 
 needed for hair identification . the microscopic view for cuticular scales : in the cuticular scale 
 structure , the morphological characteristics of the hair shaft can be used in the 
 differentiation of species [ 14 , 17 ] .
thus , we examined the cuticular scale structures in the shaft region 
 of the hair samples in this study .
hair cuticular scales are summarized in table 2table 2.cuticular scale structures of korean mammal hair .
all cuticular scale structures in the hair shaft regions of rodentia and lagomorpha hairs 
 showed the petal - shaped pattern .
eothenomys regulu , apodemus 
 peninsulae , pteromys volans and tamias 
 sibiricus showed a broad diamond - shaped petal ( fig .
1a , 1d , 1 g and 1hfig . 1.scanning electron micrographs of cuticular scale structures from rodentia and 
 lagomorpha hair shafts .
( a ) eothenomys regulus , ( b ) apodemus 
 agrarius , ( c ) rattus norvegicus , ( d ) apodemus 
 peninsulae , ( e ) lepus coreanus , ( f ) sciurus 
 vulgaris , ( g ) pteromys volans , ( h ) tamias 
 sibiricus .
all scale bars indicate 50 m . ) ; apodemus agrarius , rattus norvegicus and 
 sciurus vulgaris showed a narrow diamond - shaped petal ( fig .
1b , 1c and 1f ) ; lepus coreanus 
 had the appearance of an elongated petal ( fig . 

nyctereutes procyonoides and martes flavigula 
 showed a broad diamond - shaped petal ( fig .
( a ) nyctereutes procyonoides , ( b ) mustela 
 sibirica , ( c ) lutra lutra , ( d ) martes 
 flavigula , ( e ) prionailurus bengalensis .
all scale bars 
 indicate 50 m . ) , while mustela sibirica , lutra lutra and 
 prionailurus bengalensis showed a narrow diamond - shaped petal ( fig .
artiodactyla did not show a 
 petal - shaped pattern in the hair shield or shaft , and only simple wave patterns were 
 observed throughout the hair .
nemorhaedus caudatus , bos taurus 
 coreanae , hydropotes inermis , capreolus 
 pygargus and moschus moschiferus showed a regular wave pattern , 
 while sus scrofa showed an irregular wave pattern ( fig . 3fig .
( a ) hydropotes inermis , ( b ) capreolus 
 pygargus , ( c ) moschus moschiferus , ( d ) nemorhaedus 
 caudatus , ( e ) sus scrofa , ( f ) bos taurus 
 coreanae .
the external morphology of the hair of three deer species ( hydropotes 
 inermis , capreolus pygargus and moschus 
 moschiferus ) in the family artiodactyla was quite similar according to the naked 
 eye , showing a regular wave in the hair cuticular scale structure .
capreolus 
 pygargus showed a regular wave with a pineal shape , while moschus 
 moschiferus showed a frilled regular wave ( fig .
3a , 3b and 3c ) . to observe the cuticular scale structures of three species of 
 insectivora
crocidura lasiura , 
 crocidura shantungensis and mogera robusta showed a 
 narrow diamond - shaped petal .
( a ) crocidura lasiura , ( b ) crocidura 
 shantungensis , ( c ) mogera robusta , ( d ) 
 pipistrellus abramus .
( a , b ) 
 eothenomys regulus , ( c , d ) apodemus agrarius , ( e , 
 f ) rattus norvegicus , ( g , h ) apodemus peninsulae . 

( a , b ) lepus coreanus , ( c , d ) sciurus 
 vulgaris , ( e , f ) pteromys volans , ( g , h ) tamias 
 sibiricus .
( a ) eothenomys regulus , ( b ) apodemus 
 agrarius , ( c ) rattus norvegicus , ( d ) apodemus 
 peninsulae , ( e ) lepus coreanus , ( f ) sciurus 
 vulgaris , ( g ) pteromys volans , ( h ) tamias 
 sibiricus .
all scale bars indicate 50 m . scanning electron micrographs of cuticular scale structures from carnivora hair 
 shafts .
( a ) nyctereutes procyonoides , ( b ) mustela 
 sibirica , ( c ) lutra lutra , ( d ) martes 
 flavigula , ( e ) prionailurus bengalensis .
all scale bars 
 indicate 50 m . scanning electron micrographs of cuticular scale structures from artiodactyla hair 
 shafts .
( a ) hydropotes inermis , ( b ) capreolus 
 pygargus , ( c ) moschus moschiferus , ( d ) nemorhaedus 
 caudatus , ( e ) sus scrofa , ( f ) bos taurus 
 coreanae .
all scale bars indicate 50 m . scanning electron micrographs of cuticular scale structures from insectivora hair 
 shafts .
( a ) crocidura lasiura , ( b ) crocidura 
 shantungensis , ( c ) mogera robusta , ( d ) 
 pipistrellus abramus .
( a , b ) 
 eothenomys regulus , ( c , d ) apodemus agrarius , ( e , 
 f ) rattus norvegicus , ( g , h ) apodemus peninsulae . 

( a , b ) lepus coreanus , ( c , d ) sciurus 
 vulgaris , ( e , f ) pteromys volans , ( g , h ) tamias 
 sibiricus .
all scale bars indicate 150 m . the microscopic view for medulla structures : the medulla structures were 
 observed in the shield and shaft regions of the hairs .
however , four orders have no 
 characteristic medulla structure ( carnivora , artiodactyla , insectivora and chiroptera ) in 
 their hair shaft ; thus , hair shield regions are included as figures ( figs . 7 , 8 and 9fig . 7.light micrographs of medulla structures from carnivora hair shafts and shields .
( a ) 
 nyctereutes procyonoides , ( b ) mustela sibirica , 
 ( c ) lutra lutra , ( d ) martes flavigula ,
hair medulla structures are summarized in table 3table 3.medulla structures of the hair of korean mammal hair .
( a ) 
 nyctereutes procyonoides , ( b ) mustela sibirica , 
 ( c ) lutra lutra , ( d ) martes flavigula , ( e ) 
 prionailurus bengalensis .
rodentia and lagomorpha showed a multicellular in rows structure in the hair shield region . 

additionally , eothenomys regulus , apodemus agrarius , 
 rattus norvegicus , sciurus vulgaris , pteromys 
 volans , tamias sibiricus and lepus coreanus 
 showed a multicellular in rows structure in the hair shield region .
apodemus 
 peninsulae showed simple composition of numerous cells in the hair shield region 
 ( fig .
however , the medulla structure was 
 separated into three types in the hair shaft region .
eothenomys regulus 
 showed a ladder - like unicellular structure , while apodemus agrarius and 
 rattus norvegicus showed a multicellular in rows structure . 

apodemus peninsulae also showed multicellular structures , and 
 sciurus vulgaris , pteromys volans , tamias 
 sibiricus and lepus coreanus showed a zipper - shaped 
 multicellular structure ( fig .
a net - shaped 
 multicellular structure with scallops was observed in the hair shields of all carnivora 
 species , with the exception of nyctereutes procyonoides . in the net - shaped 
 medulla structure ,
lutra lutra 
 and prionailurus bengalensis showed a thick cortex layer and vacuoles , 
 respectively ( fig .
the hair shaft of 
 mustela sibirica , martes flavigula , lutra 
 lutra and prionailurus bengalensis showed an irregular 
 unicellular structure , while nyctereutes procyonoides showed a net - shaped 
 multicellular structure throughout the hair .
artiodactyla showed the same medulla structure 
 from the shaft to the shield , contrary to other orders , which showed different structures in 
 the shaft and shield .
hydropotes inermis , capreolus 
 pygargus and moschus moschiferus showed a mesh structure in the 
 medulla ( fig .
hydropotes inermis , ( b ) capreolus 
 pygargus , ( c ) moschus moschiferus , ( d ) nemorhaedus 
 caudatus , ( e ) sus scrofa , ( f ) bos taurus 
 coreanae .
all scale bars indicate 150 m . ) ; nemorhaedus caudatus showed a net - shaped multicellular structure 
 with a cortex layer ( fig .
8d ) ; sus 
 scrofa and bos taurus coreanae showed a columnar structure 
 ( fig . 8e and 8f ) .
crocidura 
 lasiura and crocidura shantungensis showed a ladder - like 
 unicellular regular structure in the shield and shaft regions ( fig . 9a and 9bfig .
( a ) crocidura lasiura , ( b ) crocidura 
 shantungensis , 
 ( c)mogera robusta , ( d ) pipistrellus 
 abramus .
however , mogera robusta showed a unicellular irregular structure 
 in the shield ( fig .
9c ) . pipistrellus 
 abramus was different from other orders , as it had no medulla structure ( fig .
( a ) hydropotes inermis , ( b ) capreolus 
 pygargus , ( c ) moschus moschiferus , ( d ) nemorhaedus 
 caudatus , ( e ) sus scrofa , ( f ) bos taurus 
 coreanae .
( a ) crocidura lasiura , ( b ) crocidura 
 shantungensis , 
 ( c)mogera robusta , ( d ) pipistrellus 
 abramus .
the identification key : the key was constructed based on three categories : 
 macroscopic view , microscopic view for cuticular scales and microscopic view for medulla 
 structures ( table 4table 4.hair identification key of korean mammals ) .
twenty - three species were identified at the species level with our 
 identification key ; however , some species belonging to the family muridae , sciuridae and 
 soricidae were not possible to distinguish with medulla and cuticular scales .
previous 
 research reported that hair identification keys were ineffective in distinguishing hair in 
 shrews and moles with cuticular scales .
thus , 
 crocidura lasiura and crocidura shantungensis were found 
 to belong to the shrew family and mogera robusta to belong to the mole 
 family , using macroscopic view characteristics , such as a hair profile and general 
 appearance .
in this study , we observed the difference in cuticular scale structures and medulla 
 structures in the hair samples of 23 species .
although the morphologies of hairs were 
 similar among korean terrestrial mammals , hair cuticular scales and medulla structures are 
 sufficient to distinguish between species and orders and can be used to construct an 
 identification key . in the examined hair samples , the medulla hair shaft structure was generally unicellular 
 .
however , the medullas of rodentia and 
 lagomorpha showed a multicellular structure in the hair shaft and shield , while the hair 
 shaft of carnivora showed a net - shaped multicellular structure with scallops .
these 
 differences are the basis for distinguishing among these orders . moreover , due to fact that 
 the tiny square - shaped structure of leporidae is also found in other species in lagomorpha 
 , we argue that it is characteristic of 
 lagomorpha .
the identifying characteristic of artiodactyla is that the medulla structure is 
 consistant throughout the entire hair . 

interestingly , the medulla structure of nemorhaedus caudatus is similar to 
 that of carnivora .
the hair of nemorhaedus caudatus has been confused with 
 that of nyctereutes procyonoides due to the similar external morphology of 
 the hair . to distinguish between these two species
, the cuticular scales must be 
 analyzed . because the medulla structures of all three species in insectivora showed the same 
 unicellular structure , it is difficult to distinguish among crocidura 
 lasiura , crocidura shantungensis and mogera 
 robusta .
thus , this key is not appropriate for distinguishing among these three 
 species ; however , hair length and hair color can be used to easily distinguish among these 
 species ( table 4 ) .
crocidura 
 lasiura , crocidura shantungensis and mogera 
 robusta exhibit nodes and inter - nodes in the hairs , which are morphological 
 characteristics of these species .
mammals fine 
 hairs generally have nodes and inter - nodes , and it 
 appears that their body hairs are fine as an adaption for digging .
crocidura 
 lasiura and crocidura shantungensis had the same medulla and 
 cuticular structures as north american soricidae and sri lankan shrews .
therefore , we argue 
 that these traits are characteristic of soricidae [ 9 , 
 14 ] . in artiodactyla ,
the macroscopic characteristics and medulla structures of 
 hydropotes inermis , capreolus pygargus and 
 moschus moschiferus are the same . in this case , the medulla structure 
 can not be used as an identifying feature among these three species .
however , we found that 
 the cuticular scales were different among the three species ( fig .
these different cuticular scales can be used as 
 an identification key to distinguish among these species ( table 4 ) . upon inspection ,
the whole hair type of rodentia , lagomorpha and carnivora is characterized 
 by a thick shield ( fig .
( a ) artiodactyla , ( b ) 
 rodentia , lagomorpha and carnivora , ( c ) insectivora , ( d ) chiroptera . a : node ,
the whole hairs of artiodactyla , insectivora and chiroptera were line type , node 
 type   and coronal type , respectively ( fig .
although it is not known whether hair type 
 is related to diet type , we were able to use cuticular scales to determine feeding ecology 
 at the order level .
the cuticular scales of carnivores and omnivores were an irregular wave , 
 petal shaped pattern and a coronal shaped pattern .
we simply suggest that the petal shaped pattern can only be used to differentiate 
 between carnivores , omnivores and herbivores .
( a ) artiodactyla , ( b ) 
 rodentia , lagomorpha and carnivora , ( c ) insectivora , ( d ) chiroptera .
the hair of sus scrofa can be easily classified by the naked eye and is 
 quite thick , bristly and split at the top ( table 
 1 ) . because the hair of sus scrofa can be easily distinguished 
 from that of other animals , our identification key chart was started with the hair of 
 sus scrofa(table 4 ) , as shown 
 in de marinis and aspera . because the hair of some 
 animal can not be classified using cuticular scales and medulla structures , the hair of those 
 animals should be classified by macroscopic view for hair profile and hair general 
 appearance .
many studies have constructed identification keys of mammal hair , but the present study is 
 first conducted in korea .
the identification key presented in this study provides a 
 foundation for ecological field research , forensic science and the food safety in korea . 

furthermore , we suggest adding cross - sections of hair , body regions , ages and hair width to 
 create a more complete identification key for korean mammal hair .
 abstractthe hair microstructures of korean terrestrial mammals from 23 species ( 22 wild 
 and one domestic ) were analyzed using light and scanning electron microscopy ( sem ) to 
 construct a hair identification key . 
 the hairs were examined using the medulla structures 
 and cuticular scales of guard hairs from the dorsal regions of mature adult animals . 
 all 
 cuticular scale structures in the hair of rodentia , lagomorpha , carnivora and insectivora 
 showed the petal pattern , and those of artiodactyla and chiroptera showed the wave pattern 
 and coronal pattern , respectively . 
 rodentia , lagomorpha and carnivora showed 
 multicellular , and insectivora and artiodactyla showed unicellular regular , mesh or 
 columnar in the medulla structures , respectively . 
 chiroptera did not show the medulla 
 structures in their hair . 
 we found that it is possible to distinguish between species and 
 order based on general appearance , medulla structures and cuticular scales . 
 thus , we 
 constructed a hair identification key with morphological characteristics from each 
 species . 
 this study suggests that hair identification keys could be useful in fields , such 
 as forensic science , food safety and foraging ecology . 
MATERIALS AND METHODS
RESULTS
DISCUSSION