| Our previous study found that mtDNA genome of Malayan pangolin(Manis javanica)contained a clade(named G4)of which genetic distance from other samples reached species level,suggesting G4 might be a cryptic species.In order to test the existence of the cryptic species,we carried out traditional morphological study,skull morphometric study and scale patterning.We first tested 13 body morphological measurements on 78 Malayan pangolins using principal component analysis(PCA),clustering analysis and regression analysis.Results showed PC1,representing body length,and PC2,representing mid-claw length,number of rows of dorsal scale,explained 68.24%total variance.However,G4 samples did not significantly separate from other samples,not supporting the hypothesis that G4 was a cryptic species.We further reconstructed 3D structure of 37 skulls analyzed morphometric characteristics based on 75 landmarks.Statistics showed G4 sample was significantly different from other skulls in centroid size,Mahalanobis distance and Procrustes distance(p<0.05).PCA and Conical variable analysis further supported the divergence of G4 from other samples and showed G4 and extended roof of maxilla and narrowed orbits.Therefore,skull morphometrics supported G4 is cryptic species.In addition,we established a scale coding system based on Malayan pangolin and Chinese pangolin(n=5 each species)to study the variations of pattern and number of scale within and between species.Results showed the scale coding system was able to accurately reveal the intra-and inter-specific variation of total number of scales(head scales not included),rows of dorsal scales,numbers of scales along tail edge and on four limbs(p<0.001).It was also found that the last low of scale on forelimbs growing in reverse direction,forming a "∧" shape and differing between Malayan and Chinese pangolins.The scale coding system provides an effective tool for scale analysis and species identification. |
