A photo-guide to the two most different subspecies of the roan antelope: Hippotragus equinus koba of West Africa versus Hippotragus e. equinus/cottoni of southern Africa

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INTRODUCTION

The roan antelope (Hippotragus equinus, https://www.inaturalist.org/taxa/42332-Hippotragus-equinus) is an unusually widespread species of African bovid.

It spans the continent from far-West Africa to Eritrea, and southward to subtropical South Africa (https://upload.wikimedia.org/wikipedia/commons/e/e1/Roan_Antelope_Hippotragus_equinus_distribution_map.png and https://www.researchgate.net/figure/21-The-geographic-range-of-roan-antelope-in-the-1800s-Du-Plessis-1969-and-today-IUCN_fig2_278698501).

Given this vast range, we might expect that distinct subspecies occur (https://www.researchgate.net/figure/The-distribution-of-roan-antelope-in-Africa-Anonymous-2006-with-subspecies-delineations_fig1_290478320).

However, Groves and Grubb (2011, pages 198-201, including Table 53, in https://zmmu.msu.ru/files/%D0%91%D0%B8%D0%B1%D0%BB%D0%B8%D0%BE%D1%82%D0%B5%D0%BA%D0%B0%20%D0%9F%D0%B0%D0%B2%D0%BB%D0%B8%D0%BD%D0%BE%D0%B2%D0%B0/grubb-groves-2011_taxonomy_ungulates.pdf), in their taxonomic revision of all the ungulates of the world, failed to verify any subspecies of the roan antelope.

Their revision was based on museum specimens, ignoring photographic evidence such as that now available electonically.

Factors that have retarded/complicated verification of subspecies of the roan antelope in the past include:

  • individual variation combined with small numbers of specimens from any given geographical area (Groves and Grubb 2011),
  • far more sexual dimorphism in South Sudan than at similar latitudes in West Africa (Groves and Grubb 2011),
  • questionable disjunction in the distribution of the nominate subspecies, between South Africa and Namibia, and
  • the lack, to this day, of photos of bakeri/doggetti/scharicus in inaccessible South Sudan (https://news.mongabay.com/2007/06/massive-wildlife-population-discovered-in-southern-sudan/).

MY APPROACH: HIPPOTRAGUS EQUINUS KOBA Vs HIPPOTRAGUS EQUINUS EQUINUS/COTTONI

My perusal of observations in iNaturalist, and photos elsewhere on the Web, has shown certain fairly consistent differences, particularly in colouration, between the subspecies at the extremes of the geographical range.

Most of these subspecific differences were unbeknownst to Groves and Grubb (2011), and to this day no other taxonomist seems to have noticed them.

Please bear in mind that all of the following are subject to individual variation - which is more important than sexual differences.

The ground-colour of the West African subspecies (H. e. koba) tends to be relatively bright-hued (Groves and Grubb 2011), with minimal grizzling and relatively short pelage. The hues are difficult to compare photographically, owing to vagaries of illumination and technique.

However, the extreme length and pallor of the beard, shown in the following captive specimens of Hippotragus equinus equinus/cottoni, are - as far as I know - never seen in H. e. koba:
adult female https://www.alamy.com/a-close-up-profile-portrait-of-a-roan-antelope-hippotragus-equinus-it-shows-the-head-and-neck-together-with-large-antlers-image429376262.html?imageid=51F04DDC-EFAB-4CE4-B304-781CE27CA2CB&p=224192&pn=3&searchId=907fcf51e051a28f272ac53440026b09&searchtype=0
juvenile https://www.shutterstock.com/image-photo/close-roan-antelope-beautiful-herbivore-1713171139.

Another fairly obvious difference is that, in the West African subspecies (H. e. koba) relative to the southern African subspecies (H. e. equinus/cottoni), dark pelage can be

Let us now examine, in particular, the tendency - consistently visible in photos - for the dark pelage on the face to be more extensive in the West African than in the southern African subspecies.

HOW TO SCRUTINISE THE FACE

A conspicuously pale feature to focus on is the preorbital tuft, located anterior and ventral to the eye.

Dear Reader, can you spot the difference between https://www.inaturalist.org/observations/61091684 and https://www.shutterstock.com/image-photo/roan-antelope-hippotragus-equinus-mammal-1521109436, in the size and shape of the preorbital tuft?

In infancy in both subspecies, the nucleus of the dark 'mask' appears, on

From this nucleus the darkness spreads (https://www.alamy.com/roan-antelope-hippotragus-equinus-female-both-sexes-have-long-curved-scimitar-shaped-ribbed-horns-black-and-white-facial-markings-long-ears-image398724544.html?imageid=9C93FB19-3D12-4AE0-BF38-AAFEA8A9CAEE&p=77483&pn=1&searchId=a5e37347722537f38c2dc3ebc9b10b9f&searchtype=0), according to age and sex,

This spread tends ultimately to be greater in H. e. koba than in H. e. equinus/cottoni; in fully mature males of the former, the face becomes mainly black.

In H. e. koba, even the following are subject to discoloration in some individuals:

VARIOUS DETAILED DIFFERENCES

Now, let us approach various facial and other features in detail:

In the West African subspecies,

PAIRWISE PHOTO-COMPARISONS

In the following pairwise comparisons, I illustrate the above aspects of ssp. koba of West Africa relative ssp. equinus/cottoni of southern Africa:

DISCUSSION

One of the most remarkable facts about the roan antelope is how little it varies across a vast - and somewhat disjunct - geographical distribution.

As a result, populations more than ten thousand kilometres apart (Senegal, https://upload.wikimedia.org/wikipedia/commons/3/3c/Senegal_%28orthographic_projection%29.svg, versus North West Province of South Africa, https://upload.wikimedia.org/wikipedia/commons/f/fc/North_West_in_South_Africa.svg) appear so similar, in photos, that their subspecific distinction could be doubted.

However, there are two differences that, although slight, may as well be categorical in the overall impression they leave on the human viewer. These are

  • the southern African subspecies qualifies for the description of 'roan' colouration, whereas the West African subspecies does not, and
  • in adult males in full-frontal view, the conspicuousness of the face is owing mainly to the blackish component in the West African subspecies, vs the whitish component in the southern African subspecies.

Were it the historical case that the species had become well-known in West Africa (francophone) before South Africa (anglophone), it would probably not have been given the name 'roan antelope' (French: 'antilope rouanne'). A more apt name for H. e. koba might have been 'antilope masquee' ('masked antelope').

This is because the ground-colour in West Africa is not reminiscent of roan colouration in the domestic horse (https://upload.wikimedia.org/wikipedia/commons/f/fc/Red_roan_Quarter_Horse.jpg and https://en.wikipedia.org/wiki/Roan_(color) and https://www.deviantart.com/hunter-raider/art/Coat-Color-Guide-2023-Roan-965502025).

Perhaps the first diagnostic feature to focus on, in most photos, is the preorbital tuft, which is whitish, surrounded by dark, short pelage.

The following, of H. e. equinus/cottoni, show the maximum development of the whitish preorbital tuft:
https://www.shutterstock.com/image-photo/closeup-resting-roan-antelope-hippotragus-equinus-2177832261 and https://www.chesterzoo.org/our-zoo/animals/roan-antelope/.

The following, of H. e. koba, shows how much smaller this feature is in the West African subspecies:
https://www.shutterstock.com/image-photo/roan-antelope-hippotragus-equinus-savanna-found-1391679644.

The difference in the size of the preorbital tuft is

  • apparent already in infants, and
  • consistent with the overall difference: H. e. equinus/cottoni is the hairier/shaggier also on the neck/throat, torso, and anterior surface of the ear pinnae.

However, it is noteworthy that

  • the latter generalisation does not extend to the dark tuft - typical of the whole species - at the tip of the ear pinna. In both subspecies, this feature varies mainly ontogenetically and individually, not geographically, and
  • the facial emphasis on darkness in H. e. koba does not apply to the ear pinna, which in mature males not only loses the dark tuft seen in juvenile males, but also tends to lose any apical darkness whatsoever.

The West African subspecies is larger-bodied than the southern African subspecies. Mature males weigh respectively about 300 kg and 250 kg (https://sportsafield.com/2021/its-a-roan/).

To the trained eye, this difference is hinted at by the proportionately slightly smaller post-withers mane-tuft in H. e. koba (https://www.inaturalist.org/journal/milewski/87946-has-the-post-withers-mane-tuft-of-hippotragus-evolved-in-mimicry-of-oxpeckers-buphagus-part-1#).

The caudo-ischial flag (https://www.inaturalist.org/posts/85734-oryx-in-posteriolateral-view-an-interspecies-comparison-of-adaptive-colouration#) is somewhat more poorly-developed in H. e. koba than in H. e. equinus/cottoni.

The converse is true in the case of an incipient/residual pedal flag. This pattern is slight, even in H. e. koba.

Posted on January 13, 2024 01:27 AM by milewski milewski

Comments

What is the dark feature on the lower lip?

https://www.inaturalist.org/observations/103681241

Posted by milewski 5 months ago
Posted by milewski 5 months ago

The following individual shows the maximum development of dark/pale contrast on the hindquarters in posteriolateral view, in the West African subspecies:

https://www.inaturalist.org/observations/25801218

Posted by milewski 5 months ago

Does the mane begin farther from the occiput than in the southern African subspecies?

https://www.inaturalist.org/observations/17942082

Posted by milewski 5 months ago

The following video contains some clear depictions:

https://www.youtube.com/watch?app=desktop&v=Cgy0R938mdU

Posted by milewski 5 months ago

The following shows flehmen in mature male of the West African subspecies. Please note the complete loss of the dark feature at the apex of the ear pinna:

https://www.facebook.com/photo/?fbid=705715644918042&set=a.553610316795243&locale=es_ES

Posted by milewski 5 months ago

The following is unusual in showing clearly an infant individual (probably about one month old) of the West African subspecies:

Please note a) that dark on the tail is more precocial than that on the face, and b) the pale preorbital tuft is small.

https://www.africaimagelibrary.com/media/38bfbf0c-2120-11e0-8287-8bc0e7630dc0-roan-antelope-hippotragus-equinus-reserve-de-bandia-senegal

Posted by milewski 5 months ago

EXTREMELY CLEAR DEPICTION OF COLOURATION

https://www.reserveafricainesigean.fr/en/animals/roan-antelope/

Posted by milewski 5 months ago

The following, in Kruger National Park, is an exceptionally clear illustration of 'roan colouration', similar to that in the domestic horse:

https://howieswildlifeimages.files.wordpress.com/2022/05/2021-09-18_m1x-p9183964_dxo.jpg

Posted by milewski 5 months ago

This plus subsequent comments:

Adolescent males in Kruger National Park:

https://howieswildlifeimages.files.wordpress.com/2022/05/2021-09-18_m1x-p9183968_dxo.jpg

Posted by milewski 5 months ago

The following nicely illustrates how small the whitish preorbital tuft is in the West African subspecies:

https://www.africaimagelibrary.com/media/626ef2be-2120-11e0-a7cb-6ff07bbaab0d-roan-antelope-hippotragus-equinus-reserve-de-bandia-senegal

Posted by milewski 5 months ago

Here are unusual photos of infants of the roan antelope.

In the following (?4 weeks old), please note the suggestion of a fibular/tibial flag, and the fact that the dark apical ear-tufts have yet to appear:

https://www.flickr.com/photos/gilli8888/34599741036?

In the following (?6 weeks old), please note the precociality of the darknes on the tail:

https://www.veronasera.it/cronaca/parco-natura-viva-top-five-nascite-particolari-27-settembre-2016.html

Posted by milewski 4 months ago
Posted by milewski 4 months ago

An unusually clear illustration of the length of the tail at various ages in Loxodonta africana, which has a shorter tail than in Elephas maximus:

https://www.everypixel.com/q/animal-breeding?image_id=10845680870747623680

Posted by milewski 4 months ago

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