Ungulate taxonomy revisited: the evidence for the splits of G&G

They certainly are niger today. They imported kirkii for an attempted breeding program back in the day.

~Thylo

 

Beisa oryx

The Beisa oryx (Oryx beisa) is an antelope from the arid regions of Eastern Africa. It has long been considered as a subspecies of the Gemsbok (Oryx gazella), but there are clear genetic, morphological and karyotypic differences. Generally two subspecies are recognized:

O.b. beisa Beisa oryx, Ethiopia, Somalia, Djibouti, Kenya N of Tana river
O.b. callotis Fringe-eared oryx, Kenya S of Tana river and NE Tanzania

G&G recognize both subspecies as separate species and split up beisa in beisa in the Horn of Africa and gallarum in Kenya. Additionally they state that the beisa from Awash Valley (Ethiopia) are probably another species based on another 8 skins

Sample sizes

Skins
beisa 8
gallarum 16
callotis presumably 2

Skulls & Horns
beisa 7-9
gallarum 40-54
callotis 15-19

Sample sizes are generally very low, with the exception of gallarum. Sample sizes for most horn measurements are extremely limited (1, 12-14 and 4-5 respectively)

Skins

beisa described as more ochraceous, were gallarum is a purer gray in pelage colour. callotis is said to be darker, duller and browner than gallarum. beisa is said to have the facial bands joining up, whereas they generally remain separate in gallarum and callotis. The flank band is on average slightly thicker in beisa than in gallarum and callotis. The dorsal stripe is thicker in all beisa skins than in gallarum and callotis samples. The dorsal stripe in the 2 callotis samples is also smaller than in gallarum in general, but is lacking completely in one gallarum specimen. A very clear difference between callotis and the other two taxa is the presence of black tufts of hair on the tips of the air in callotis, hence the common name.

Skulls & Horns

The skull of callotis is described as generally broad, but this is only a difference on average and most samples fall within the range of gallarum and beisa. In terms of skull characteristics gallarum and beisa are indistinguishable. The horns of callotis are on average both broader and wider apart at the tips when compared to gallarum though there is some overlap with gallarum (but not much). callotis horns also have slightly less rings on average, but there is wide overlap in this characteristic.

Additional data

Masembe et al. (2006) sampled Mtdna of Beisa oryx in Kenya and Tanzania and thus covered the range of gallarum and callotis. The found 3 clearly separate lineages, one corresponding nicely with the range of callotis, the other two were mixed in the range of gallarum. The Tana river formed a strong border and the sequence diversion between callotis and the 2 other lineages, which were mixed, was about 10%. Unfortunately no samples were taken from Ethiopia, Somalia or Djibouti to see whether there was any difference between beisa and gallarum. Karyotypically callotis does not differ from the other taxa.

Summarizing

For now I see no reason to split the beisa subspecies up in two separate species: gallarum and beisa. They should however be treated as subspecies given the pelage differences. It would be interesting to analyze Mtdna also from the Horn of Africa. callotis is genetically clearly distinct from the other taxa and is also clearly distinct morphologically, both in overall colour and in the presence of ear tufts. I think it would thus make sense to treat the Fringe-eared oryx as a separate species: Oryx callotis and recognize two subspecies in the Beisa oryx: Oryx beisa beisa in the Horn of Africa and Oryx beisa gallarum in Kenya.

Oryx beisa gallarum

@lintworm , Samburu National Reserve, Kenya


Oryx beisa beisa

@lintworm , Awash NP, Ethiopia

Oryx callotis

@thor , San Diego Safari Park, USA

Reference

Masembe et al. (2006): https://www.researchgate.net/profil...ridization/links/53edd6120cf26b9b7dc629c5.pdf


next: the remaining Hippotragini

 

Addax

The Addax (Addax nasomaculatus) is a distinct antelope from the Sahel and Sahara region and is considered monotypic. It is currently restricted to a few isolated patches in Mauritania, Niger and Chad.

"summer pelage"

@ro6ca66 , Marwell Wildlife, UK

"winter" pelage

@jayjds2 , San Antonio Zoo, USA


Gemsbok

The Gemsbok (Oryx gazella) is an Oryx from SW Africa, which was considered conspecific with the Beisa oryx (Oryx beisa), but is now treated as a distinct species.


@Great Argus , San Diego Safari Park, USA


Arabian oyrx

The Arabian oryx (Oryx leucorix) is the smallest Oryx and the only one to occur outside of Africa, it was nearly extinct, but has since been re-introduced at several locations across the Arabian peninsula.


@ThylacineAlive , Gladys Porter Zoo, USA


Scimitar-horned oryx

The Scimitar-horned oryx (Oryx dammah) originally occurred throughout the semi-arid regions around the Sahara desert. It is currently listed as extinct in the wild, but several semi-wild populations have been established in e.g. Senegal, Tunisia and Morocco.


@Tim May , Whipsnade Zoo, UK

Next: Blue duiker

 

A note to all the the Duikers that will be covered here. G&G did not perform any new research for Ungulate Taxonomy when it comes to duikers. They completely base themselves on their own revision of the Cephalophini, which was published in 2001 as an Appendix to the book Duikers of Africa; Masters of the African forest floor by V.J. Wilson. All splits they describe in Ungulate Taxonomy are basically elevating what they then recognized as subspecies as distinct species and all data shown in the coming posts comes from that book.

Blue duiker

The Blue duiker (Philantomba monticola) is a small antelope that occurs throughout Central and Southern Africa. It has been considered conspecific with the Maxwell's duiker (Philantoma maxwelli), but are now generally recognized as a separate species. Many Blue duiker formerly in zoos were hybrids between Maxwell's and Blue duiker, which led to very low birthrates.

Blue duiker have generally been subdivided in a northern group with gray legs and a southern group with reddish legs. Kingdon recognizes 13 subspecies:

Southern group
P.m. monticola Cape provinces S Africa
P.m. bicolor (including fuscicolor) South of the Zambezi to KwaZulu Natal, S-Africa
P.m. hecki, Malawi, Zambia, E of Luangwa Valley, N Mozambique
P.m. anchietae N Angola
P.m. defriesi Zambia, west of Muchanga escarpment
P.m. simpsoni between lower Congo River and Kasai River

Northern group
P.m. congicus from the Cross river to the Congo river (Cameroon, Gabon, Congo)
P.m. melanorheus Bioko Island
P.m. aequatorialis E of congicus throughout DR Congo to W Uganda and Sudan and as far south as Namoyo
P.m. musculoides E Uganda to Kenya
P.m. lugens Southern Tanzanian highlands
P.m. schusteri, Eastern Arc mountains of Tanzania
P.m. sundevalli (including pembae), Pemba, Zanzibar and Mafia Island as well as coastal E Africa

G&G recognize a total of 10 separate species, treating musculoides and sundevalli as subspecies of aequatorialis and lumping schusteri with lugens.

Sample sizes

Skins
congicus at least 15
melanorheus 12
aequatorialis at least 2
musculoides unknown
lugens unknown
sundevalli unknown
simpsoni unkown
hecki unknown
bicolor unknown
monticola unknown
anchietae unknown
defriesi unknown

Horns/skulls (males/females)
congicus 44/59
melanorheus 11/6
aequatorialis 43-49/34-46
musculoides 7-11/3-10
lugens 3/2-3
sundevalli 2/2
simpsoni 17/15
hecki 3/2
bicolor 2/2-5
monticola 9/1
anchietae 12/3
defriesi 5/7-9

Known sample sizes are severely limited for 5 out of 10 proposed species (defriesi, monticola, bicolor, hecki, lugens) and for one subspecies sundevalli.

Skins

congicus, melanorheus, aequatorialis, lugens are all gray-legged. simpsoni, hecki, bicolor, monticola, anchietae and defriesi are red-legged. congicus is described as bright gray brown dorsally and with a dark brown horizontal stripe that marks the sharp transition to the paler haunch and the broadly white underparts. melanorheus is said to be more constrastly marked than congicus, whereas aequatorialis is a more drab-brownish taxa. lugens is described as very dark gray brown, without a strong contrast between flanks and dorsum and gray-gray fawn undersides. simpsoni is said to have a narrow blackish-brown dorsal region, with red-brown flanks, a poorly marked transition stripe. hecki differs in being not blackish-brown but dark brown on the dorsal region, light-red flanks and having a black light fawn gray. bicolor is darker than hecki but less so than lugens with dark rufous-orange flanks and a throat with an orange tinge. monticola is somewhat light-gray or fawn and only slightly reddened haunches. anchietae differs from monticola in having a black tail and being pale gray-brown dorsally and gray flanks. Haunches are only red on the back, fading to grey in the front. defriesi is said to be closely related to hecki but paler and more contrasty. The dark-gray dorsal zone is said to be quite distinct. Flanks are pale red-fawn and unlike anchietae the white of the underparts is also present on the inner part of the upperleg.

Horns & skulls

congicus and aequatorialis are inseparable based on skull and horn characteristics, even though G&G claim that aequatorialis has shorter nasals, there is no evidence for that at all. melanorheus is somewhat smaller than aequatorialis and congicus, though it is not smaller than some populations of congicus and aequatorialis, though it has significantly longer horns than those populations (but not longer than other aequatorialis and congicus populations). lugens is similar ins size to aequatorialis and though G&G claim it has longer horns, the very limited samples are hardly larger than some aequatorialis populations and the same size as the sundevalli subspecies. simpsoni is said to be very small, but is not any smaller than neighboring aequatorialis or any of the red-legged taxa. hecki is on average somewhat larger than most red-legged taxa, but this is based on very few samples and is the same size as some anchietae or hecki populations. bicolor, monticola and simpsoni are on average somewhat smaller than the other red-legged taxa, but this is either based on very small sample sizes, but there is overlap with most other taxa as well. G&G state that in some taxa females are larger than males, but based on their data (in which they ignore standard errors), there doesn't seem to be any real distinction. In some taxa : sundevalli, lugens, musculoides, bicolor the premaxillary bones always reach the nasals, whereas in other taxa they do not always do that (though except for simpsoni they do in the majority).

Additional data

Surprisingly there seems to be no genetic work to compare different Blue duiker populations.

Summarizing

There are some slight differences between taxa in the overall colouration, but the only thing that really jumps out is the division in gray-legged and red-legged taxa, where the red-legged taxa often have some red on the sides as well. Skulls and horns are overall very similar between taxa and many difference described by G&G are hardly present at all, or not distinctive. I therefore see no reason to split the Blue duiker into separate species for now, though it would be very interesting to see genetic data across this species range, as there is some variation present.

Philantomba monticola congicus

@Tim May , Colchester Zoo, UK

Philantomba monticola monticola

@ThylacineAlive , Wildlife World Zoo & Aquarium, USA

Philantomba monticola bicolor

@Andrew_NZP , Maryland Zoo, Baltimore, USA

no pictures of any of the other subspecies seem to have been uploaded.

next: the remaining Philantomba duikers.

 

Any photos of the current Blue Duikers at Maryland Zoo, New Zoo, Hattiesburg Zoo, Kansas City Zoo, Moody Gardens, or Safari West will be of bicolor. San Antonio, Abilene, Birmingham, Lowry Park, and Montgomery all have animals listed as bicolor and non-subspecies.

~Thylo

 

Maxwell's duiker

The Maxwell's duiker (Philantomba maxwelli) has been considered conspecific with the smaller Blue duiker, but is clearly morphologically and genetically distinct and now generally treated as a distinct species. Three subspecies are often recognized:
P.m. maxwelli, from Senegal to Sierra Leone
P.m. danei, Sierra Leone
P.m. liberiensis, Liberia


@ThylacineAlive, Bronx Zoo, New York, USA


Walter's duiker

Walter's duiker (Philantomba walteri) is a recently described species that occurs in the Dahomey Gap between the distribution of Maxwell's and Blue duiker. In many characteristics it is intermediate between these taxa, but it is distinct both genetically and morphologically.

No pictures of Walter's duiker have been uploaded in the gallery.

Next: Common duiker

 

Common duiker

The Common duiker (Sylvicapra grimmia), also known as the Grey, Crowned or Bush duiker, is one of the most widely spread antelopes of Africa occuring throughout sub-saharan Africa with the exception of the rainforest belts and the arid parts of the horn of Africa. There is quite some variation between regions and even within very limited areas. Based on a review by G&G in 2001 Kingdon recognized 14 different subspecies, though range limits are often unclear:

S.g. grimmia Cape region
S.g. caffra S Africa, S Mozambique and E Zimbabwe
S.g. steinhardti Northern Cape region, Namibia to Angola and Botswana
S.g. splendidula Angola, N from Mupa to DR Congo, W Zimbabwe, Zambia west of Luangwa river
S.g. orbicularis N Mozambique, Zambia east of Luangwa river, Tanzania, E Kenya and S Somalia
S.g. hindei Kenyan highlands east of the Great Rift Valley
S.g. nyansae Kenya west of the Great Rift Valley, Uganda, S Sudan, SW Ethiopia
S.g. altivallis Afroalpine zones of the Aberdares (Uganda) and probably also on Mt Kenya
S.g. lobeliarum Afroalpine zones of Mt. Elgon on the Kenyan/Ugandan border
S.g. subsp. nov. Mt. Kilimanjaro
S.g. madoqua Ethiopian highlands and Awash Valley
S.g. campbelliae from Burundi to Chad and west to Ghana & Sierra Leone
S.g. pallidior, Sahel zone
S.g. coronata border area of Guinea, Guinea-Bissau, Senegal and the Gambia.

It is worth noting that I have seen both madoqua and orbicularis on both lowland and highland localities (Awash vs. Dinsho and Kigoma vs. Kitulo respectively) and the highland localities are easily told apart in the field.

G&G elevate both pallidior and coronata to species status and leave the other taxa as subspecies as the differences are not clear enough. I will just focus on the evidence to elevate pallidior and coronata to species status and leave the other subspecies as those subspecies are also accepted by others.

Sample sizes

Skins
No sample sizes for skins are reported

Skulls (males/females)
coronata (3/2-3)
pallidior (7-8/2)
campbelliae (+- 50/+- 23)

Sample sizes are small for both split taxa, but relatively high for campbelliae which is the subspecies closest to both species in terms of range. No horn measurements are reported

Skins

coronata is unique among all Common duiker in being bright orange-yellow in color with no speckling in the adults and the mid-dorsal region has a somewhat darker reddish shade. Facial blaze is deep red not extending to the crest. Leg stripes are very indistinct on both hind and front legs (and does not reach the knee in the front) and there is also no throat streak. pallidior is a pale buff and weakly speckled, the facial blaze extends to the crest, but is more diffuse than in campbelliae. The fore leg stripe in pallidior is long but diffuse and pallidior has longer ears. campbelliae is described as ochery to gray-buff and heavily speckled. Facial blaze is dark and extending to the crest. campbelliae has no throat streak and the stripe on the front leg is well marked and reached the knee.

Skulls

Both pallidior and coronata are described as being very small, but the skull length widely overlaps with campbelliae. There is also wide overlap in the bizygomatic breadth, pre-orbital length and nasal lengths between all three taxa; the other skull measurements taken. This is the same for both males and females.

Additional data

I have not found any genetic work being done on Common duiker

Summarizing

coronata is indeed clearly distinct in skin pattern from the campbelliae (and also from all other taxa), pallidior is also somewhat distinct in skin pattern, but not as clear. There is however no differences in skulls and there are no genetic studies as far as I am aware to back up any claims for splitting. G&G even noted in 2001 about coronata that: "this is easily the most distinctive of the subspecies, and could be raised to specific rank depending on its relations with campbelliae wherever their ranges meet". This wisdom was apparently lost to them in the following years. For now there is absolutely no reason to elevate either coronata or pallidior to species status, though some genetic studies would be interesting.

Sylvicapra grimmia caffra

@Newzooboy , Johannesburg Zoo, South Africa

Sylvicapra grimmia madoqua

@lintworm , Bale Mountains NP, Ethiopia

Sylvicapra grimmia campbelliaeOR nyansae

@Nick@Amsterdam , Uganda Wildlife Education Centre


next: Bay duiker

 

Bay duiker

The Bay duiker (Cephalophus dorsalis) is a heavily built duiker from primary rainforests in Western and Central Africa. The Bay duiker is currently divided into two subspecies clearly subdivided by the Dahomey gap.

C.d. dorsalis from Guinea-Bissau to Togo, West of the Dahomey gap
C.d. castaneus East of the Dahomey gap, from extreme E Nigeria S to Angola and east to the Rwnzori mountains and Albertine rift valley, though it is now presumably extinct in Uganda.

G&G elevate both subspecies to species status. Interestingly they put the border between both taxa at the Adamawa mountains in Cameroon as samples from E Nigeria had a black face instead of red. Red faces are typical of dorsalis whereas the forehead can be both red or black in castaneus

Sample sizes

Skins
dorsalis (15)
castaneus (50)

Skulls
dorsalis (27)
castaneus (73-74)

Sample sizes are good for both taxa

Skins

dorsalis is said to be a bright chestnut red, with always a black(ish) blaze on the face. The dorsal stripe is said to be comparatively narrow, but no measurements are given. castaneus is darker in color and the crest and face are said to usually be a deep red not black, this is however not the case in about 33% of the castaneus sample, where the forehead color is black or blackish (excluding the samples from E Nigeria). The dorsal stripe is said to be broader in castaneus. dorsalis is smaller than castaneus with no overlap: head+body length is 760-850 mm in dorsalis vs. 883-1032 mm in castaneus

Skulls

dorsalis skulls are significantly smaller than castaneus skulls with 156-174 mm in dorsalis and 185-202 mm in castaneus. Nasal breadth is on average somewhat broader in castaneus, but there is wide overlap. The pre-orbital length is also significantly longer in castaneus, without overlap. Teeth are also longer in castaneus, though there is some overlap in measurements there.

Additional data

I am not aware of any genetical data on the differentiation of Bay duiker taxa.

Summarizing

Bar the mystery population in Eastern Nigeria both taxa are clearly separated geographically and castaneus is significantly bigger than dorsalis without overlap in multiple measurements. The pelage is relatively similar, but there are some differences, albeit with some overlap. Bay duiker would be a high priority species for genetic sampling as it is very possible that the Western and Eastern bay duiker actually represent separate species. For now it would make sense to already treat these taxa as a species group pending genetic evaluation, as this is clearly the direction the morphology is pointing.

Cepalophus (dorsalis) dorsalis


@jbnbsn99 , Ellen Trout Zoo, USA

No pictures have been uploaded for Cephalophus (dorsalis) castaneus.

Next: Yellow-backed duiker

 

I have made a re-assessment of the Southern lechwe I treated it as a species complex with four separate species, but actually the morphological analysis claiming clear differences between the taxa is statistically flawed, leading to a possible exaggeration of the actual differences (see the Tsessebe story). Though some of the taxa have been split as long as some of the Hartebeest splits, actual genetic differentiation is very limited, as are the morphological differences. I now think that retaining the Southern lechwe as one species with four well-defined subspecies is a better approach.

 

Yellow-backed duiker

The Yellow-backed duiker (Cephalophus silvicultor) is the largest of the duikers and had a wide distribution from Senegal in the west to Kenya in the east and Zambia in the south. This species is very adaptable and occurs in a wide range of wooded habitats from primary forest to forest - savanna mosaics. Currently four species are recognized

C.s. silvicultor from Senegal east to the Niger river
C.s. longiceps east from the Niger river to the Congo river and east to South Sudan and the Western Rift Valley
C.s. curticeps A montane subspecies from between the Western and Eastern Rift Valleys, E DR Congo, Rwanda, Burundi and SW Kenya
C.s. ruficrista South of the lower Congo river , including much of DR Congo, N Angola and Zambia

G&G split curticeps and retain the other three taxa as subspecies of silvicultor

Sample sizes

Skins
silvicultor 7
longiceps 58-72
curticeps 8-11
ruficrista 28-35

Skulls
silvicultor 8
longiceps 49
curticeps 4
ruficrista 22

Sample sizes for curticeps are small and not much better for silvicultor. ruficrista and longiceps are well represented though.

Skins
curticeps is said to be darker with a narrower and darker dorsal triangle. The dorsal triangle is indeed on average very narrow in the Kenyan samples, but most of the samples fall within the variation of longiceps. The curticeps samples from Rwanda fall completely within the variation of the longiceps and ruficrista and are actually among the widest dorsal triangles. There is no overlap at all in the dorsal triangle measurements from Rwanda and Kenya. The dorsal haunch spots are well developed in 9 of 11 curticeps samples and never really absent. These dorsal haunch spots are always present in ruficrista and can be absent in longiceps and are always absent in silvicultor.

Skulls
curticeps always has a shorter skull <260 mm, whereas the other taxa are at least 263 mm in length and often longer. Preorbital length in curticeps is also shorter than in the other taxa, but toot length is similar to ruficrista and nasal length measurements overlap with longiceps from Ituri in DR Congo.

Additional data
I am not aware of any data on genetics of Yellow-backed duiker

Summarizing
Differences in the skins between curticeps and the other taxa are rather unconvincing, the only reliable characteristic seems to be that curticeps is somewhat darker. Differences in haunch spots and dorsal triangles are inconsistent and fall within the variation of other taxa. curticeps does seem to be somewhat smaller than the other taxa, but this is based on a very small sample size. I therefore do not see a good reason to elevate curticeps to species level and it seems valid to retain Yellow-backed duiker as one species with four subspecies.


@Tomek , Tiergarten Nuremberg, Germany


@Blackduiker , Los Angeles Zoo, USA

next: Ogilby's duiker

 

The captive population will be nominate fyi

~Thylo

 

Ogilby's duiker

The Ogilby's duiker (Cephalophus ogilbyi) is a duiker with a disjunct distribution throughout Western Africa. Generally three subspecies have been recognized, each with clearly a separate distribution. G&G elevated the brookei subspecies to species level in 2001, an approach not followed by Kingdon, who says that this is likely a species complex. To complicate matters Ogilby's duiker is genetically indistinguishable from the similar Peter's duiker (Cephalophus callipygus) (see e.g. Hassanin et al. 2012). The reason why, whether this is widespread hybridization or whether Peter's duiker are actually part of the Ogilby's duiker is not clear. I won't go into details about that, but it is important to be aware of. In skull measurements there is no difference at all between callipygus and ogilbyi, but there are some pelage differences. According to Kingdon the subspecies of Ogilby's duiker are as follows:

C.o. ogilbyi (Ogilby's duiker) Bioko Island and the border area of Nigeria and Cameroon
C.o. brookei (Brooke's duiker) Sierra Leone to Ghana
C.o. crusalbum (White-legged duiker) Gabon and extreme northwest Republic of Congo

G&G elevate all subspecies to species level.

Sample sizes
Sample sizes for skins are not given

Skulls
ogilbyi 22
crusalbum 9
brookei 7

Skins
ogilbyi is described as bright ochery with a dark dorsal stripe extending onto the tail. The dorsal stripe is 11-30 mm broad and legs are coloured like the body. Hairs on the centre of the neck can be reversed and if this is the case it is over a wide zone. crusalbum has legs white from the knee and the dorsal stripe is on average broader (25-60 mm). Reversal of hair stream in the neck is narrower if present. crusalbum young are more strongly speckled. brookei has a paler dull golden color overall, becoming red gold on the dorsum. Dorsal stripe is 27-66 mm broad, but it is indistinct before the shoulders and narrows into a thin line on the rump. Reversal of neck hairs occurs in most specimens and is over a fairly wide zone.

Skulls
All taxa are indistinguishable based on skull measurements given in the tables, though ogilbyi from Bioko Island are somewhat larger than on the mainland. Females are slightly larger than males on average. ogilbyi has a prominent frontal boss, which is less prominent in crusalbum and apparently even smaller in brookei. The rostrum of brookei is bowed outwards, which is not the case in ogilbyi. Premaxillae are widely suturing with nasals in brookei, but less so in ogilbyi.

Additional data
There does not seem to be any studies comparing dna samples between the three taxa + Peter's duiker.

Summarizing
The three taxa are distinct in skin colouration, have widely separated distributions and some minor skull differences. Without genetic data and the link to Peter's duiker resolved, I would keep all three taxa as subspecies for now. Given the rarity of this species, genetic research is of extremely high importance as it is possible that Ogilby's duiker actually consists of multiple species.

No pictures of any of the Ogilby's duiker taxa have been uploaded to the gallery.

Reference
Hassanin et al. (2012): https://www.sciencedirect.com/science/article/pii/S1631069111002800

next: Weyn's duiker

 

Respect for the great thread ! If someone is interested in G&G book, please send me PM.

 

Weyn's duiker

The Weyn's duiker (Cephalophus weynsi) is a medium-sized duiker from the Congo rainforest, the Albertine Rift Valley and forest remnants in Uganda and Kenya. Kingdon does not recognize a definite number of subspecies though multiple have been described throughout its range.

G&G split Weyn's duiker into 3 species:
C. weynsi from the Congo rainforest
C. johnstoni W Kenya and parts of Uganda
C. lestradei extreme S Sudan, W Uganda and Rwanda

This species has been described from W Tanzania, but there is no recent evidence of its occurrence in either the Gombe or Mahale Mountains, though both sites are heavily camera-trapped.

Sample sizes

No sample sizes for skins are given.

Skulls
weynsi 48-49
johnstoni 17
lestradei 4

Sample size for lestradei is very small, but good enough for other taxa.

Skins

johnstoni and weynsi are indistinguishable based on skins. lestradei is darker than the other taxa, described as dark olive grey-brown with varying reddish tones as compared to dull chestnut-brown. The dorsal stripe is well marked, but not sharply bordered in lestradei, but ill-defined in the other taxa.

Skulls

johnstoni has the smallest and weynsi the largest skulls. The skull length measures do not overlap between the taxa. Tooth lengths are more similar, though johnstoni has shorter teeth, although the difference is minimal and there might be overlap. Pre-orbital and nasal measurements are also smallest for johnstoni and might well be significantly smaller, there is however wide overlap between weynsi and lestradei for these measurements, though on average weynsi is somewhat larger.

Additional data

I am not aware of any genetical data comparing the different Weyn’s duiker taxa.

Summarizing

lestradei is distinguishable based on the skin colouration from johnstoni and weynsi. johnstoni is in multiple measurements significantly smaller than than the other taxa. lestradei and weynsi can also likely be distinguished on skull length. There is however no genetic data to back these PSC splits and the morphological differences, though present are not huge. For now I would propose to keep Weyn’s duiker as a single species, but with 3 distinctive subspecies. Subsequent molecular work would however be interesting to see whether there is good reason to do split this species.

No pictures of any of the Weyn's duiker taxa have been uploaded to the gallery.

next: White-bellied duiker

 

White-bellied duiker

The White-bellied duiker (Cephalophus leucogaster) is a medium-sized duiker that occurs from the Gulf of Guinea east into the Congo rainforest, restricted to areas under 1000 meters. Traditionally two subspecies have been recognized:

C.l. leucogaster Gabon, Equatorial Guinea, Cameroon, Congo, DR Congo except NE
C.l. arhenii NE DR Congo

G&G elevate both subspecies to species status

Sample size

Skins
leucogaster 55
arhenii 54

Skulls (males/females)
leucogaster 17/19
arhenii 24/28

Skins

arhenii is said to be paler and browner than leucogaster, which can be somewhat reddish. The dorsal stripe is well defined in leucogaster, but more diffuse in arhenii. The dorsal stripe width is on average broader in leucogaster, but the leucogaster samples from the Sangha river overlap widely in breadth with the arhenii samples.

Skulls

arhenii is described as being slightly larger, though true on average, the taxa overlap widely in size and both taxa are practically indistinguishable based on skull characteristics.

Additional data

I am not aware of any genetical work to differentiate between leucogaster and arhenii

Summarizing

As the the skulls are practically indistinguishable and the pelage differences are relatively small I see no reason why these taxa should be split. It seems to be perfectly valid to retain both as subspecies.

No photos of White-bellied duiker have been uploaded to the gallery.

next: Red duiker

 

Red duiker

The Natal red duiker (Cephalophus natalensis) and Harvey's duiker (Cephalophus harveyi) have either been treated as subspecies or separate species in the past, though currently they are often regarded as separate species (e.g. Kingdon). Both taxa are however similar and the validity of both species has been extensively discussed, also recently. I therefore chose to give them a bit more attention. Fortunately G&G cover both taxa extensively in their 2001 Duiker taxonomy review.

C. natalensis from SE Tanzania through Malawi and Mozambique to Swaziland and NE South Africa
C. harveyi NW Malawi through C Tanzania to coastal Kenya and extreme SW Somalia, with scattered populations in the Kenyan highlands and Ethiopian highlands.

Sample sizes

No sample sizes for skins are given

Skulls (males/females)
harveyi 12-16/6-10
natalensis 13-16/15-23

Skins

natalensis is a more pale orange brown than harveyi and natalensis legs are only slightly greyer, whereas in harveyi the legs are dark grey to brownish black. natalensis has a somewhat darker facial midline, but in harveyi this is much more pronounced also in the crest.

Skulls

Though harveyi is described as the larger taxon there is large variation within each taxon and wide overlap between harveyi and natalensis, especially the natalensis from S Tanzania are just as big as highlang harveyi and larger than harveyi from the coast.

Additional data

Multiple genetic studies have pointed at the fact that the difference in Mtdna is rather small between harveyi and natalensis (van Jansen van Vuuren & Robinson 2001; Hassanin et al. 2012). They argue that it would be better to treat them as subspecies rather than species. Additionally Foley et al. report that the characters of the red duikers of SE Tanzania are intermediates between harveyi and natalensis indicating a large hybrid zone.

Summarizing

The morphological differences are relatively small (though when comparing only natalensis from Transvaal with harveyi from the highlands, the conclusion would look rather different…). Adding the limited genetic differentiation between the taxa it seems better to lump harveyi back into natalensis, which is exactly how G&G treated harveyi back in 2001.

Cephalophus natalensis natalensis (Natal red duiker)

@AdrianW1963 , ZSL London Zoo, UK

Cephalophus natalensis harveyi

@Hix , Arusha NP, Tanzania

References
Hassanin et al. 2012: https://www.sciencedirect.com/science/article/pii/S1631069111002800

van Jansen van Vuuren & Robinson 2001: https://www.sciencedirect.com/science/article/pii/S1055790301909625

Next: Black-fronted duiker

 

Black-fronted duiker

The Black-fronted duiker (Cephalophus nigrifrons) is a medium-sized duiker closely related to the Red duiker. It occurs in forests from sea level to over 4000 meters. The species is widely distributed from central Africa to mountain forests in East Africa. The Rwenzori red duiker (Cephalophus rubidus) was originally considered a subspecies of Black-fronted duiker, but based on scant genetic evidence it is now treated as a distinct species. Generally 5 subspecies are recognized:

C.n. nigrifrons lowland forests of the Niger delta, S Cameroon, Gabon, Equatorial Guinea, Congo, DR Congo, N Angoa and S Central African Republic
C.n. kivuensis mountains along the Albertine Rift Valley in DR Congo, Rwanda, Burundi & Uganda
C.n. fosteri Mt. Elgon on the Ugandan-Kenyan border
C.n. hooki Aberdares, C Kenya, and Mt Kenya
C.n. hypoxanthus, Itombwe massif in E DR Congo

fosteri, hooki and hypoxanthus are elevated to species status, whereas kivuensis is retained as subspecies of nigrifrons.

Sample sizes

Skins
7 skins were seen for hypoxanthus, sample sizes for other taxa are not mentioned

Skulls (males/females)
nigrifrons 18/21
kivuensis 11-13/12
hypoxanthus 1
fosteri 9/10
hooki 3/3

Sample sizes are extremely limited for hooki and hypoxanthus

Skins

nigrifrons is described as shining chestnut-brown, with the black on the forelegs as far up as the elbow and in the hindlegs up to the hock. Chest is black, just as the forehead, the chin is yellow or sometimes white. kivuensis has a more contrasting pelage with grey-black limbs, black facial blaze, a pale reddish chin and thick and coarse fur. fosteri is described as brownish with face and side of the neck reddish, not grey. The chin is white and the coronal tuft short and black and the hair is thick and coarse. hooki also has thick and coarse fur but is chestnut or reddish-grey, with reddish face and side of the neck. The chin is reddish-white and the face blaze bordered by a red stripe, the coronal tuft is as in fosteri. hypoxanthus is described as pale with a light yellow-chestnut color. Legs are grayish rather than black, the hair is very long, but soft.

Skulls

The single hypoxanthus skull is similar in size to nigrifrons, but with shorter nasals, whereas kivuensis is somewhat smaller than nigrifrons in all measurements and there seems to be hardly any overlap. fosteri and hooki are extremely similar in skull measurements and both are a lot smaller than the other taxa.

Additional data

I am not aware of any genetical data on the different taxa of Black-fronted duiker.

Summarizing

The Black-fronted duiker is an interesting species, with some quite distinct groups. There is the larger nigrifrons from lowland forests. The very small mountain isolates hooki and forsteri of E Africa and two somewhat intermediate mountain taxa in E DR Congo and the Albertine Rift Valley. It is somewhat interesting that G&G did not split kivuensis even though, especially for their standards, it is distinct from nigrifrons. All taxa seem recognizable from each other and given the allopatric distributions and the presence of multiple montane taxa this would be a species for which genetic research is of very high importance. I would not be surprised if at least hooki + forsteri is generally split in the future, but also hypoxanthus and kivuensis could be potentially distinct. For now it seems better to retain them in one species until more data is available.

No pictures have been uploaded of any of the Black-fronted duiker taxa.

next: the remaining Cephalophus species.

 

Zebra duiker

The Zebra duiker (Cephalophus zebra) is a small duiker from the W African rainforests. It is considered monotypic.


@Blackduiker , Los Angeles Zoo, USA


Jentink's duiker

Jentink's duiker (Cephalophus jentinki) is a large endangered duiker that occurs in primary forests from E Sierra Leone to W Cote d'Ivoire. This species is currently considered monotypic.


@Baldur , Gladys Porter Zoo, USA


Abbott's duiker

Abbott's duiker (Cephalophus spadix) is a large endangered duiker from Tanzanian mountain forests. This species is considered monotypic and has hardly ever been photographed. It is therefore no surprise that no pictures of this species have been uploaded to the gallery.


Black duiker

The Black duiker (Cephalophus niger) is a large duiker from Western Africa, which occurs mainly in secondary and disturbed forests. The Black duiker is considered monotypic.


@ThylacineAlive , Los Angeles Zoo, USA


Ader's duiker

The Ader's duiker (Cephalophus adersi) is a critically endangered small to medium sized duiker from Kenyan coastal forests and Zanzibar. Ader's duiker is considered monotypic.

No pictures of Ader's duiker have been uploaded to the gallery


Red-flanked duiker

The Red-flanked duiker (Cephalophus rufilatus) is medium-sized widespread duiker that occurs in a wide range of forest habitats from Senegal in the west to Uganda in the east, though it does not occur in most of DR Congo or Gabon. Two subspecies are generally recognized:
C.r. rufilatus Senegal to the Chari river
C.r. rubidior Chari river to the Nile valley

Cephalophus rufilatus rufilatus

@ThylacineAlive , Los Angeles Zoo, USA

No pictures of rubidior have been uploaded to the gallery.


Rwenzori red duiker

The Rwenzori red duiker (Cephalophus rubidus) is a medium sized duiker from the (sub-)alpine regions of the Rwenzori mountains on the border between Uganda and DR Congo. The Rwenzori duiker is considered monotypic and sometimes treated as a subspecies of the Black-fronted duiker.

No pictures of Rwenzori red duiker have been uploaded to the gallery.


Peter's duiker

Peter's duiker (Cephalophus callypigus) is a medium sized duiker from western Central Africa. Its taxonomic status is somewhat unclear, as it might be the same species as the sympatric Ogilby's duiker or there might be extensive hybridization between the two. For now it is considered a monotypic species.

No pictures of Peter's duiker have been uploaded to the gallery.

With all African antelopes finished it is time to continue with the non-African members of the Antilopini, starting with Saiga.

 

Are we sure Zebra Duikers aren't Thylacines in disguise? They sure look like it.