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IntraspecificmorphologicalvariationofCryptotiscolombiana (SoricidaintheCentralAndesofColombia

DavidMarnCardona1 andSergioSolari1,2

1GrupoMastozoologa&ColeccinTeriolgica,Universidad deAntioquia2InstitutodeBiologa,UniversidaddeAntioquia,Medelln,Colombia

troduction

rews of the genus Cryptotis(Soricidae) are endemic to New World, ranging from eastern US and Canada to therthern Andes of Peru. Although phylogenetic affinities

ong species are not unambiguously resolved, two Southmerican groups are recognized: (a) the thomasigroup,h eight South American species, and (b) the nigrescens

oup, with four Central American and two Colombianecies. Within the last group, C. colombianais only knownm the Central Cordillera of Colombia. Because of the fewailable specimens, no comprehensive studies ofrphological and morphometric variation have been

mpleted for this taxon, and a complete diagnosis isking. However, recent mammal surveys have increased number of specimens and locality records for C.ombianaallowing us to assess its geographic variationng the Central Cordillera.

troduction

rews of the genus Cryptotis(Soricidae) are endemic to New World, ranging from eastern US and Canada to therthern Andes of Peru. Although phylogenetic affinities

ong species are not unambiguously resolved, two Southmerican groups are recognized: (a) the thomasigroup,h eight South American species, and (b) the nigrescens

oup, with four Central American and two Colombianecies. Within the last group, C. colombianais only knownm the Central Cordillera of Colombia. Because of the few

ailable specimens, no comprehensive studies ofrphological and morphometric variation have been

mpleted for this taxon, and a complete diagnosis isking. However, recent mammal surveys have increased number of specimens and locality records for C.ombianaallowing us to assess its geographic variationng the Central Cordillera.

thods

used morphological traits of the humerus to discriminateong species of the groups thomasiand nigrescenspresent

he Central Cordillera. Whereas C. colombianabelongs innigrescensgroup, C. medelliniais part of the thomasiup. In addition to this comparison, we also includedcimens of C. thomasiand C. mexicana. For therphometric analyses we selected 20 craniodentalasurements (Fig. 1), using a digital caliper to the 0.01 mm,

recorded these for 101 Cryptotisspecimens from threealities (Fig. 2). To assess (non-geographic) variation ine, we used age classes as proposed by Rudd (1955) forrex. In that proposal, individuals of age class 2 aresidered adults, by tooth wear and the premaxilla

ination (Fig 3 4). Data were analyzed through ancipal Component Analysis (PCA), grouping available

cimens by collecting locality. All statistical analyses wereusing PAST ver. 1.88 software (Hammer et al. 2001).

thods

used morphological traits of the humerus to discriminateong species of the groups thomasiand nigrescenspresent

he Central Cordillera. Whereas C. colombianabelongs innigrescensgroup, C. medelliniais part of the thomasiup. In addition to this comparison, we also includedcimens of C. thomasiand C. mexicana. For therphometric analyses we selected 20 craniodentalasurements (Fig. 1), using a digital caliper to the 0.01 mm,

recorded these for 101 Cryptotisspecimens from threealities (Fig. 2). To assess (non-geographic) variation ine, we used age classes as proposed by Rudd (1955) forrex. In that proposal, individuals of age class 2 aresidered adults, by tooth wear and the premaxillaination (Fig 3 4). Data were analyzed through a

ncipal Component Analysis (PCA), grouping availablecimens by collecting locality. All statistical analyses were

using PAST ver. 1.88 software (Hammer et al. 2001).

Results

Our comparison of the available humerus showith both C. thomasiand C. mexicana, so werepresenting the nigrescensgroup and theref

colombiana. Among the whole series there wdifferences in morphology of humerus, but theoverall size with specimens from northern AnCentral Cordillera showed larger humerus (FiSome of the diagnostic craniodental traits for(according to Woodman & Timm, 1993 and Wwere more variable than expected. Among thmargin of unicuspids U1-U3 (Fig.6 ), the joint

ramus and the coronoid process (Fig. 7), andthe two elements of the ectoloph of M1 (Fig. 8

considered a unique synapomorphy for the nWoodman (2003). At some point of the variaoverlap with those of the thomasigroup. Eveused to diagnose C. colombianaamong the nshowed similar variation to that between grouform of the foramen on the posterior edge of tthe petromastoid, as well as the size of the pa(Fig. 9). In particular, the lingual notch betwecondyles was not shallow, being as much evimedellinia(Fig. 10). The M3 was complex, wprotocone, paracone, parastyle and mesostylhypocone was evident in young and adults bu

animals.Among other traits not commonly used for di

variation in relative size of U4 (Fig. 11), and thlateral view (Fig 12). These characters allowspecimens from central Antioquia and Caldasvariability hindered to use them to diagnose thThe PCA showed an incipient separation in t(Fig. 13), between the specimens from RisaraCordillera) and those from Antioquia and Caldthe First Component. This is usually a size coshrews is related to the overall size of specim

Antioquia and Caldas overlap along that comalong the second component (which is a shap

However, the morphologic analysis did not subetween these geographic groups. Measuresignificantly to this separation were the length

(ZP) and the breadth of M2 (M2B); it is very inof the zygomatic plate was a highly variable cstudy series. was a highly variable character

Results

Our comparison of the available humerus showith both C. thomasiand C. mexicana, so werepresenting the nigrescensgroup and theref

colombiana. Among the whole series there wdifferences in morphology of humerus, but theoverall size with specimens from northern AnCentral Cordillera showed larger humerus (FiSome of the diagnostic craniodental traits for(according to Woodman & Timm, 1993 and Wwere more variable than expected. Among thmargin of unicuspids U1-U3 (Fig.6 ), the jointramus and the coronoid process (Fig. 7), andthe two elements of the ectoloph of M1 (Fig. 8considered a unique synapomorphy for the n

Woodman (2003). At some point of the variaoverlap with those of the thomasigroup. Eveused to diagnose C. colombianaamong the nshowed similar variation to that between grouform of the foramen on the posterior edge of tthe petromastoid, as well as the size of the pa(Fig. 9). In particular, the lingual notch betwecondyles was not shallow, being as much evimedellinia(Fig. 10). The M3 was complex, wprotocone, paracone, parastyle and mesostylhypocone was evident in young and adults bu

animals.Among other traits not commonly used for di

variation in relative size of U4 (Fig. 11), and thlateral view (Fig 12). These characters allowspecimens from central Antioquia and Caldasvariability hindered to use them to diagnose thThe PCA showed an incipient separation in t(Fig. 13), between the specimens from RisaraCordillera) and those from Antioquia and Caldthe First Component. This is usually a size coshrews is related to the overall size of specimAntioquia and Caldas overlap along that comalong the second component (which is a shapHowever, the morphologic analysis did not su

between these geographic groups. Measuresignificantly to this separation were the length

(ZP) and the breadth of M2 (M2B); it is very inof the zygomatic plate was a highly variable cstudy series. was a highly variable character

Discussion

In the Central Cordillera of Colombia, the genus Cryptotispresents variablecharacteristics in both size and shape that make it difficult to discriminate amongspecies. Although the use of humerus morphology allows discriminating species

groups, in the absence of this evidence the identification of species could be verydifficult. Because of this, we could not find one character or combination of

characters that allowed unambiguous identification of shrew species in this region.The only synapomorphy proposed for skull characters in the nigrescensgroup,was too variable to validate its use. In this way, our conclusions are much asthose by Vivar et al. (1997), who questioned the use of skull characters toseparate among species groups in Cryptotis. However, we were unable to identifyany craniodental characteristic to validate the distinction of C. medellinia.Our analysis confirms that shape of the humerus is a good character to separatespecies groups in Colombia, but so far we only identify the nigrescens group in theCentral Cordillera (C. medelliniabelongs to the thomasi group). Although thediagnosis of C. colombianaincludes several craniodental and external traits, mostof them were so variable as to render their use as ambiguous. The degree of

variation among localities is too large, and this is an expected benefit of the use oflarger series. We cannot discard that more than one taxon of the nigrescensgroup may be present in the Central Cordillera.

Using morphometric analyses we could identify three morphotypes, all defined byunique combinations of size and shape. Specimens from Antioquia and Caldascan be grouped by the size and relative position of U4, and within the group twosub-groups can be further distinguished by the length of the zygomatic plate. But,its variation prevents its use as a good discriminant character. This incipientseparation can be related to the presence of the Samana and the Arma riversnear the border between these departments. It is worthy to mention thatspecimens with large humerus (showed in blue circle in the PCA analysis) have

body measurements similar to those reported for C. medellinia, so it is possiblethat what is being referred to this species is another representative of thenigrescensgroup and perhaps an older synonym for C. colombiana.

We believe that these analyses, although preliminary, suggest the need for amore comprehensive study of the genus in South America, especially in Colombia

where the highest diversity of the genus occurs. Although new methods of studyand analyses are now available, ours is the first approach including large seriesfrom diverse localities and we expect to include postcranial data in a future report.The presence of the nigrescensgroup in the Central Cordillera requests a clearbiogeographic explanation, which should be part of a complete reconstruction ofits diversification in South America.

Discussion

In the Central Cordillera of Colombia, the genus Cryptotispresents variablecharacteristics in both size and shape that make it difficult to discriminate amongspecies. Although the use of humerus morphology allows discriminating species

groups, in the absence of this evidence the identification of species could be verydifficult. Because of this, we could not find one character or combination of

characters that allowed unambiguous identification of shrew species in this region.The only synapomorphy proposed for skull characters in the nigrescensgroup,was too variable to validate its use. In this way, our conclusions are much as

those by Vivar et al. (1997), who questioned the use of skull characters toseparate among species groups in Cryptotis. However, we were unable to identifyany craniodental characteristic to validate the distinction of C. medellinia.Our analysis confirms that shape of the humerus is a good character to separatespecies groups in Colombia, but so far we only identify the nigrescens group in theCentral Cordillera (C. medelliniabelongs to the thomasi group). Although thediagnosis of C. colombianaincludes several craniodental and external traits, mostof them were so variable as to render their use as ambiguous. The degree ofvariation among localities is too large, and this is an expected benefit of the use oflarger series. We cannot discard that more than one taxon of the nigrescensgroup may be present in the Central Cordillera.

Using morphometric analyses we could identify three morphotypes, all defined byunique combinations of size and shape. Specimens from Antioquia and Caldascan be grouped by the size and relative position of U4, and within the group twosub-groups can be further distinguished by the length of the zygomatic plate. But,its variation prevents its use as a good discriminant character. This incipientseparation can be related to the presence of the Samana and the Arma riversnear the border between these departments. It is worthy to mention thatspecimens with large humerus (showed in blue circle in the PCA analysis) have

body measurements similar to those reported for C. medellinia, so it is possiblethat what is being referred to this species is another representative of thenigrescensgroup and perhaps an older synonym for C. colombiana.We believe that these analyses, although preliminary, suggest the need for amore comprehensive study of the genus in South America, especially in Colombiawhere the highest diversity of the genus occurs. Although new methods of study

and analyses are now available, ours is the first approach including large seriesfrom diverse localities and we expect to include postcranial data in a future report.

The presence of the nigrescensgroup in the Central Cordillera requests a clearbiogeographic explanation, which should be part of a complete reconstruction ofits diversification in South America.

Fig. 2- Sampled localities: Antioquia, Caldas and RisaraldaFig. 2- Sampled localities: Antioquia, Caldas and RisaraldaFig. 1- Cranial and mandibularmeasurements used in this study

Fig. 1- Cranial and mandibularmeasurements used in this study

Literature CitedHammer, O., D. A. T. Harper, & P. D. Ryan(2001) PAleontological STatistics Software

Package.

Vivar, E.,V. Pacheco & M Valqui. 1997.Museum Novitates. 3202: 1-15

Woodman, N., & R. M. Timm (1993)Fieldiana, Zoology, n.s. 74: 1-30.

Woodman. N., C. A. Delgado-Velez, & C.

Cuartas. 2003. Journal of Mammalogy 84(3):832-839

Literature CitedHammer, O., D. A. T. Harper, & P. D. Ryan(2001) PAleontological STatistics Software

Package.Vivar, E.,V. Pacheco & M Valqui. 1997.

Museum Novitates. 3202: 1-15

Woodman, N., & R. M. Timm (1993)Fieldiana, Zoology, n.s. 74: 1-30.

Woodman. N., C. A. Delgado-Velez, & C.

Cuartas. 2003. Journal of Mammalogy 84(3):832-839

Fig. 3 Ranges of tooth wear, unworn inyoung animals (Classes 1 and 2)

Fig. 4 In young premaxilla lies parallel tolong axis of the skull (A)

Fig. 3 Ranges of tooth wear, unworn inyoung animals (Classes 1 and 2)

Fig. 4 In young premaxilla lies parallel tolong axis of the skull (A)

Fig. 5 Humerus of (A) nigrescensgroup from Antioquiaand Caldas, (B) nigrescensgroup from Northern Antioquiaand Risaralda, (C) thomasigroup from Oriental Cordillera

and (D) mexicanagroup from Oaxaca, Mexico

Fig. 5 Humerus of (A) nigrescensgroup from Antioquiaand Caldas, (B) nigrescensgroup from Northern Antioquiaand Risaralda, (C) thomasigroup from Oriental Cordillera

and (D) mexicanagroup from Oaxaca, Mexico

Fig. 6 (A) Convex, (B) Concave, (C)Straight posteroventral margins

Fig. 6 (A) Convex, (B) Concave, (C)Straight posteroventral margins

Fig. 7 Join of coronoid process in oblique angleFig. 7 Join of coronoid process in oblique angle

Fig. 8 The anterior element of ectoloph (M1) wasalways small than the posterior element

Fig. 8 The anterior element of ectoloph (M1) wasalways small than the posterior element

9 Different shapes and forms of Process of petromastoid,occipital process and the foramen on the posterior edge of thepanic process of the petromastoid.

9 Different shapes and forms ofProcess of petromastoid,occipital process and the foramen on the posterior edge of thepanic process of the petromastoid.

Fig. 10 Lingual notch between thetwo articular facets.

Fig. 10 Lingual notch between thetwo articular facets.

Fig. 12 (A) Hide U4 in central Antioquia, (B) VisCryptotisfrom Caldas.

Fig. 12 (A) Hide U4 in central Antioquia, (B) VisCryptotisfrom Caldas.

Fig. 11 (A and B) Small size of U4 (60%-90% smaller Antioquia, (C and D) Big size of U4 (20%-30% smaller

Fig. 11 (A and B) Small size of U4 (60%-90% smaller Antioquia, (C and D) Big size of U4 (20%-30% smaller

Fig. 13 Plot of morphometrics space and contribution ovariation. Antioquia, Caldas and Risaralda.

Fig. 13 Plot of morphometrics space and contribution ovariation. Antioquia, Caldas and Risaralda.

AcknowledgmentsCurators and staff of the collections wevisited allowed us full access andfacilities for review of specimens,specially Yaneth Muoz-Saba. Fundingfor Undergraduate Proyects CODIUniversidad de Antioquia and StaffGrupo de Mastozoologia& ColeccionTeriologica, Universidad de Antioquia.

AcknowledgmentsCurators and staff of the collections wevisited allowed us full access andfacilities for review of specimens,specially Yaneth Muoz-Saba. Fundingfor Undergraduate Proyects CODIUniversidad de Antioquia and StaffGrupo de Mastozoologia& ColeccionTeriologica, Universidad de Antioquia.

A B CD

B C

A B C D

A

A B C