In our study 24 out o f 51 males w ere identified, at subspecies level, by the museums. The species A. m elam pus has six described subspecies: A. m elam pus rendilis, A. m. suara, A. m johnstoni, A. m. petersi. A.m. m elam pus and A. m elam pus katangae.
Five o f them are represented in our sample set. (Table 4.14).
TABLE 4.14 - Subspecies of Aepyceros melampus and correspondent number of males from British Natural History Museum and Powell-Cotton Museum used in the present study.
Subspecies Males
(n)
Males’ identification numbers
A m. rendais 6 M36, M37, M38, M41, M42 and,M43 A m. suara 3 M10,M49andM51 A m. johnstoni 3 M26, M31 and M35 A .m. petersi 5 M18, M19, M20, M21 and M23 A .m. melampus 7 M2, M3 9, M44, M45, M46, M47 and M48 Total 24
An African map showing the geographical position o f these males can be seen in Figure 4.19. Into the boxes are summarised the geographical range and characteristics by w hich authors defined the Aepyceros m elam pus subspecies.
W e can observe that impalas from Namibia and A ngola are classified as A. m. p e te r si. M ales from Zam bia and M alawi are classified as ^4. m. jo hnstoni. The Kenya
and Tanzania impalas are classified respectively as A. m. rendilis and A.m . suara. Six impalas from S. Africa and one from Nam ibia are classified as A.m . m elam pus.
The distinction am ong impala subspecies is mainly based on size o f skull and horns, A. m. jo h n sto n i being the smallest. D ifferences betw een A. m. rendilis and A. m. suara are not clear fi'om the literature (Lydekker,1914; Lydekker & Dollman, 1926; Allen, 1939; Ansell,1971; B est & Raw, 1975) and, although there are references to horn
A. melampus suara
is larger than melampus with longer and more massive horns. The tips of the horns are usually more widely spread. ITie general colour above is b lis te r, being bright cinnamon-rufous. The crown of the head is blackish, and frequently a slight indication of a black face-blaze is developed.
Range Tanzania, exact limits to south and south-west not clear. Rwanda and probably south-western Uganda, southern part of the Kenya range.
TT
A. melampus petersi
known as the Angolan impala or black-faced impala, is distinguished from the typical race by the presence of a black blaze down the middle of the face below the eye and another tfirough the line of each eye. Horns are smaller than typical race.
Range: South-western Angola and north-western Namibia. T a n z a n i a A n gola om bia Imbabwe T Nqit lb 10 \ B o ts w a n a S w a zila n d S o u t h A f r ic a A. melampus rendilis
has been regarded as identical with suara. There is also frequently a more or less well developed blackish face blaze, although this is much less marked than in the Angolan race. Range: Northern part of the Kenya range and presumably eastern Karamoja, Uganda.
A. melampus johnstoni known as the Malawi impala, is very closely allied to the typical race. It is distinguished by its shorter horns and more slender skull.
Range: Northern Mozambique, Malawi, eastern Zambia, and possibly south-western Tanzania, exact limits not known.
A. melampus melampus
known as the South African impala or common impala, the horns are of medium size and more slender than in the East African races. The general colour of the UM)er surface of the body is brigjit reddish brown, and there is no dark blaze (mi the face such as is found in the Angolan race. Range: South-eastern Angola, and possibly south-western Zambia, thence the species ranges from the Zambesi river southwards, but the exact limits and inter-grading with johnstoni are not clear.
FIGURE 4.19 - Southern African map showing geographical distribution of Æ m elam pus male skull samples. The specimens identified at subspecies level are marked with different colours. The geographic range and morphological characteristics by which subspecies were defined are summarised in each box.
size ïn A. m. petersi, this subspecies is mainly distinguished by the presence o f a black stripe along the middle o f the face.
S catterplots corresponding to the three PCA s perform ed with skull and horn data w ere used to explore relationships am ong males identified at subspecies level (Figure 4.20).
The first scatterplot represents the PC A based on horn characters (Figure 4.20A). F actor loading analyses (Table 4.9 and Figure 4.10) showed that P C I represents horn size (H I, H2, H3 and H 7) and distance betw een the tips (H 4) that increases fi’om the left to the right o f the axis; and that PC2 reflects the measurem ents from th e base o f the hom cores (H5 and H6). These results indicate that A. m. rendilis has bigger and/or more widely spread horns, in contrast to A. m. jo hnstoni. The subspecies p etersi and
m elam pus are show n to have an intermediary position regarding these characters.
The second scatterplot represents the PC A based on skull characters (Figure 4.20B). F actor loading analyse (Table 4.9 and Figure 4.9) indicated that P C I represents skull length (S5 and SIO) and breadth (S I, S2, S4, S8 and S9) increasing from the left to the right o f the axis, while PC2 reflected snout (S I 2) and m olar row (S I 4) that ncrease from the bottom to the top o f the axis. So, the positions o f the males identified at subspecies level indicate that A. m. p etersi has the biggest skull, and A. m. jo h n sto n i the smallest. East and South African impalas have an intermediary position regarding these characters and as showed in PC2 they present shorter snout com pared w ith petersi.
The third and fourth scatterplots represent the PCA s based on skull and horn characters (Figure 4.20C and D). F actor loading analysis (Table 4.9 and Figure 4.11) indicated that P C I represents skull breadth (S I and S4), length (S5 and SIO) and depth (S6), horn length (H I and H 2), and inner breadth betw een the base o f the hom cores (H6)
A- Horn characters B - Skull characters 2.5 1.5 0,5 -0,5 ■1,5 -2,5 -3,5 • A m rendilis A A m suara ■ A m. johnstoni + A. m. petersi A m. m elam pus
C - Skull and horn characters (PCI x PC2)
2,0 0,5 -0,5 -2,0 -2,5 2,5 -2,5 •1,5 -0,5 0,5 1,5 PC1
D - Skull and horn characters (PC2 x PCS)
# A. m. rendilis ' A m suara ■ A, m, johnstoni + A m petersi ♦ A. m. m elam pus * + 1,4 0 + 0,8 ♦ ■ + + 0,2 • ‘ * ♦ 0 A ■ » A . * * g -0,4 ■ 0 + 0 • # -1,0 ♦ A A 0 * 0 0 A. m. rendilis -1,6 • 0 A A. m. suara * • 0 ■ A. m. johnstoni + A m. petersi -2,2 4 .1R .n 1 s o -2,5 • A.m. rendilis A A.m. suara ■ A. m. johnstoni + A. m. petersi ♦ A m. m elam pus PC1 PC2
FIGURE 4.20 - Scatterplots corresponding to male P C I vs PC2 scores from horns PCA (A); PC I vs PC2 scores from skull PCA (B); P C I vs PC2 (C) and PC2 vs PC3 (D) scores from skull and horns PCA. Males are identified by subspecies designation from museum label.
PC 2 represents maximum inner breadth betw een horns (H 5) and oral palatal ength ( S I 2). So, the position o f the males identified at subspecies level indicates that general skull and horn size increases gradually from the smaller form represented hy A. m. jo h n sto n i, to the medium A. m. m elam pus and finally the bigger A. m. rendilis, A. m. suara and A, m. petersi. Although in P C I the general skull and horn size o f jo h n sto n i
and p etersi are inversely related, in the shape axis PC2, they share the same area on the graph and in opposition to m elam pus, rendilis and suara. The PC3 axis gave no additional information, confirming A N O V A results in which this axis does not present significant differences am ong the geographic groups. These results are further discussed in section 4.4 below.