The two subspecies of black-backed jackal (Lupulella mesomelas) differ in facial shapes: ears and cheekbones

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In this Post,

'ear' means ear pinna (https://en.wikipedia.org/wiki/Auricle_(anatomy)), and
'cheekbone' means zygomatic arch (https://en.wikipedia.org/wiki/Zygomatic_arch).

There are two subspecies of Lupulella mesomelas, and no naturalist should have difficulty telling them apart.

This is partly because they live in different areas, viz.

They also differ in that the latter is several kg lighter than the former, and more predacious in habits and diet.

The two subspecies hardly differ in colouration, which is surprising, given their different climates, and the wide geographical gap separating them.

Nonetheless, in my experience, it is usually easy to distinguish the subspecies at a glance, in photographs - even if only the face is visible, and the locations are unknown.

This is based on the appearances of the ears and cheekbones.

EARS

In the nominate subspecies, the ears are small relative to the face, and the medial edge of the ear, viewed from the front, is nearly straight. By contrast, in ssp. schmidti, the ears are large relative to the face, and the medial edge is curved.

(For the location of the medial edge of the ear, please see the labelled photo in https://veteriankey.com/1-anatomy-of-the-ear/.)

Imagine flapping the ear forward, like a paper-fold.

In ssp. mesomelas, the tip of the ear would not reach the tip of the nose. This indicates that the face is large relative to the ear, or the ear is small relative to the face:

In ssp. schmidti, the tip of the ear would reach the tip of the nose. This indicates that the face is small relative to the ear, or the ear is large relative to the face.

I have no explanation, as yet, for the shapes of the ears, in adaptive terms.

CHEEKBONES

In the nominate subspecies, the cheekbones are hardly noticeable. By contrast, in ssp. schmidti, the cheekbones are prominent. This prominence is mainly because each cheekbone seems to be underscored by a shadow (https://www.istockphoto.com/photo/portrait-of-a-black-backed-jackal-gm470918901-34842462 and https://www.dreamstime.com/black-backed-jackal-lupulella-mesomelas-green-grass-image214121878).

The underscoring of the cheekbones, in schmidti, gives the face a 'pinched' appearance (https://www.dreamstime.com/stock-images-portrait-black-backed-jackal-side-canis-mesomelas-image34368354).

If this 'pinched' look were to be quantified, I suspect that this would be in the ratio of the width of the skull at the zygomatic arches (https://en.wikipedia.org/wiki/Zygomatic_arch) to the width of the skull at the maxillae (https://en.wikipedia.org/wiki/Maxilla). The muzzle of mesomelas is longer than that of schmidti.

What the subspecific differences in the facial bones seem to mean, in adaptive terms:

The East African subspecies, more specialised for predation and less likely to resort to bones or fruits, emphasises carnassial slicing (https://en.wikipedia.org/wiki/Carnassial), rather than molar crushing of food. Its jaws are, in other words, less generalised than those of the typical jackal, and this oddness can be seen in the face even at a distance.

Subspecies MESOMELAS:

All the following photos of the nominate subspecies show the nearly straight medial edge of the ear in full-frontal view, and the lack of underscoring of the cheekbones by shadows.

https://stock.adobe.com/search/images?k=%22silver-backed+jackal%22&asset_id=330308648

https://www.picfair.com/pics/010627835-cape-cross-black-backed-jackal-looking-at-the-camera

https://critterfacts.com/blackbackedjackal/

https://www.dreamstime.com/close-up-portrait-watchful-black-backed-jackal-looking-straight-camera-photographed-late-afternoon-etosha-image178642736

https://www.dreamstime.com/black-backed-jackal-canis-mesomelas-etosha-national-park-namibia-africa-image190060845

http://image.shutterstock.com/display_pic_with_logo/484132/484132,1264202077,1/stock-photo-black-backed-jackal-close-up-etosha-national-park-namibia-southern-africa-45056764.jpg

http://1.bp.blogspot.com/-d-TR66rT1Sk/UxS_3WO10HI/AAAAAAAAFSM/_dNn86Gmlvk/s1600/Black-+Blacked+Jackal+Wallpapers+(26).jpg

https://thumbs.dreamstime.com/z/black-backed-jackal-close-up-namibia-11246127.jpg

https://www.dreamstime.com/black-backed-jackal-closeup-face-portrait-closeup-face-black-backed-jackal-canis-mesomelas-photographed-namib-image217263850

https://image.shutterstock.com/z/stock-photo-a-black-backed-jackal-lying-on-the-ground-with-ears-erect-54522526.jpg

https://s-media-cache-ak0.pinimg.com/564x/74/89/a9/7489a97b9dc273ed6a0c7656b2a2b3d1.jpg

https://s-media-cache-ak0.pinimg.com/236x/60/fc/3c/60fc3ca7df6e92815e216415899763d6.jpg

http://www.alamy.com/stock-photo-portrait-of-a-black-backed-jackal-canis-mesomelas-sitting-in-wildflowers-66859021.html

Subspecies SCHMIDTI:

All the following photos of schmidti show the curved medial edge of the ear in full-frontal view, and the underscoring of the cheekbones, seemingly by shadows.

So, in subspecies schmidti,

the ears have more curved medial edges,
the face is relatively small relative to the ears (or the ears are large relative to the face), and
the face has a ‘pinched’ look, by virtue of prominent cheekbones, relative to narrow upper jaws.

https://www.shutterstock.com/image-photo/portrait-wild-jackal-blackbacked-specimen-native-672681037

https://www.istockphoto.com/photo/portrait-of-a-black-backed-jackal-gm696019404-128748331

https://www.gettyimages.fi/detail/valokuva/black-backed-jackal-male-head-portrait-rojaltivapaa-kuva/150081263?adppopup=true

https://www.dreamstime.com/royalty-free-stock-image-eyes-black-backed-jackal-image17025016

http://www.alamy.com/stock-photo-black-backed-jackal-silver-backed-jackal-canis-mesomelas-serengeti-20462541.html

http://www.alamy.com/stock-photo-stock-photo-of-a-black-backed-jackal-sitting-on-the-short-grass-plains-24942597.html

https://image.shutterstock.com/z/stock-photo-black-backed-jackal-canis-mesomelas-masai-mara-kenya-177451967.jpg

http://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-laying-on-the-ground-front-view-124307935.html

https://www.alamy.com/stock-photo-young-black-backed-jackal-close-up-42112604.html?imageid=8485E1D4-3639-4956-8F3B-D197DD56F1BE&p=83215&pn=1&searchId=009084b6cc32470209f69bad39768d05&searchtype=0

https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-ngorongoro-conservation-area-tanzania-37996411.html?imageid=25363707-7C0B-49D3-A896-5AFF36A59062&p=16403&pn=1&searchId=59127445242fbde064768ecd70e333c1&searchtype=0

Here is the comparison again, at a slightly different angle:

subspecies mesomelas:
http://l7.alamy.com/zooms/02fbea879b0f4b829482adad7f6d633e/black-backed-jackal-canis-mesomelas-namib-naukluft-park-namibia-africa-e0jjdk.jpg

subspecies schmidti:
https://thumb7.shutterstock.com/display_pic_with_logo/1084712/157842791/stock-photo-black-backed-jackel-masai-mara-kenya-157842791.jpg

הועלה ב-ספטמבר 6, 2022 02:34 לפנה"צ על ידי

milewski

תגובות

Here is a test for readers. Which subspecies is this? https://www.dreamstime.com/stock-photo-head-portrait-black-backed-jackal-neck-aka-silver-out-focus-background-accentuates-image80830133

פורסם על-ידי milewski לפני בערך 2 שנים

In the following, of ssp. mesomelas (https://www.alamy.com/black-backed-jackal-face-image445366127.html), there is no underscoring whatsoever of the cheekbones.

The following of subspecies mesomelas (https://stock.adobe.com/search/images?k=%22silver-backed+jackal%22&asset_id=458420914) may resemble schmidti, because this individual happens to have pigmentation on the fur of the cheeks. However, the shape of the cheekbones remains different.

If the following (https://www.bigstockphoto.com/image-395503001/stock-photo-the-black-backed-jackal-%28canis-mesomelas%29-standing-in-the-grass-in-the-morning-light-little-jackal) were ssp. schmidti (which it is not), it would have a 'shadow' under the cheekbone.

Thanks for all this information.

פורסם על-ידי botswanabugs לפני בערך 2 שנים

The following, of ssp. mesomelas (https://stock.adobe.com/search/images?k=%22silver-backed+jackal%22&asset_id=426395354), does seem to conform to the specifications for ssp. schmidti. This is because the cheekbones seem to be underscored, and the medial edges of the ears seem somewhat curved. However, the shape of the face is still, to a practised eye, recognisably that of the nominate ssp.

Here is another photo of the same individual: https://stock.adobe.com/search/images?k=%22silver-backed+jackal%22&asset_id=451533354.

@botswanabugs You are most welcome, and I am so glad that you enjoy this material.

shift
Canis anthus bea in the Serengeti ecosystem: https://www.dreamstime.com/jackal-walking-serengeti-plains-serengeti-tanzania-africa-jackal-walking-serengeti-plains-serengeti-national-park-image134689083

https://www.gettyimages.ie/detail/photo/jackals-looking-at-camera-with-intense-eyes-at-royalty-free-image/1335381487?adppopup=true

Testing subspecific difference in jaw form in Lupulella mesomelas:

Lupulella mesomelas is unusual in that the subspecific distinction between L. m. mesomelas and L. m. schmidti is not one of colouration, but rather one of the form of the jaws and dentition, perhaps extending to the size of the muzzle relative to the head. Over the years I have come to believe that I can identify any clear photo of adult C. mesomelas to subspecies just by looking at the face: L. m. schmidti has a ‘pinched’ look because its jaws are relatively small relative to the zygomatic width, and the shadow under the zygomatic arch tends to be deeper than in the nominate subspecies.

Since this sort of subspecific variation – with the the appearance of the rest of the animal remaining so similar – is not typical of canids, it may perhaps warrant further scrutiny.

Here I begin to test the distinction in the appearance of the head by means of comparison among photos.

The question is this:

Even if one can identify L. m. schmidti at a glance by the pattern of shading under the cheekbones, that does not necessarily mean that the actual size and shape of the muzzle differ from those of L. m. mesomelas. The obvious way to test this is to examine the head in full profile. It is with this image in mind that I have carefully chosen the various photos below.

Lupulella mesomelas mesomelas:

http://www.wildlife-pictures-online.com/image-files/black-back-jackal_rc-0211g.jpg

https://fineartamerica.com/featured/black-backed-jackal-peter-chadwick.html

https://www.alamy.com/stock-photo-black-backed-jackal-in-profile-88079594.html

https://www.dreamstime.com/stock-images-black-backed-jackal-image4074934

https://www.dreamstime.com/black-backed-jackal-portrait-southern-afrcian-savannah-image224195640

https://www.sciencephoto.com/media/726289/view/black-backed-jackal

https://www.deviantart.com/seb-photos/art/Botswana-2015-Jackal-best-side-567484980

https://www.alamy.com/portrait-of-a-black-backed-jackal-in-southern-afrcian-savannah-image434838239.html

https://www.istockphoto.com/photo/black-backed-jackal-gm91678633-1815187?phrase=jackal%20profile%20photos

Lupulella mesomelas schmidti:

https://www.dreamstime.com/stock-images-portrait-black-backed-jackal-side-canis-mesomelas-image34368354

https://media1.britannica.com/eb-media/67/1767-004-4331CF8B.jpg

https://retrieverman.files.wordpress.com/2011/11/black-backed-jackal.jpg

http://justfunfacts.com/wp-content/uploads/2016/07/jackal.jpg