Does Peters' gazelle (Nanger granti petersi) resemble genus Gazella in its differences from Grant's gazelle (Nanger granti granti)?
Peters' gazelle (Nanger granti petersi, https://www.inaturalist.org/observations?taxon_id=563632)
- occurs only in eastern Kenya, and
- differs from the other subspecies in several ways, apart from the shape of the horns in males.
The body mass of adult males is probably only about 50 kg (similar to that of males of the common impala, Aepyceros melampus), compared to 60 kg or more in nominate Nanger granti granti.
Adult females seem not to have been weighed. However, my guess is 35kg or less, compared with an average of 45 kg recorded for the nominate subspecies.
Peters' gazelle is the only subspecies lacking a lateral bleeze, in any individual of either sex and any age.
By 'lateral bleeze', I refer to a pattern on the flanks which is conspicuous enough in profile that it makes the whole figure stand out, rather than blending into the environment.
Instead of distinct bands on the flanks, Peters' gazelle retains only faint darkening on the posterior part of the flank (above the stifle-fold, https://www.inaturalist.org/journal/milewski/53569-adaptive-colouration-in-gazelles-eye-catching-highlights-above-the-stifle-fold#).
The latter darkening is extended into a fully dark flank-band in juveniles of the other subspp. (e.g. https://www.inaturalist.org/observations/8088622).
It is also retained, with additional accentuation, by some individual adult females (see https://www.inaturalist.org/observations/26410343) in populations of Nanger granti notata (https://www.inaturalist.org/observations?taxon_id=568581) living in the Laikipia region (https://en.wikipedia.org/wiki/Laikipia_County) of central Kenya.
All Nanger granti, of all ages and both sexes in all subspp., have a conspicuous whitish pattern - which I call an ischiopygal bleeze - on the buttocks and spilling on to the rump.
In Peters' gazelle, the extension of whitish on to the rump resembles the genus Gazella rather than the rest of Nanger, in
- having minimal extent, and
- being divided by a fawn mid-line.
Furthermore, in Peters' gazelle the whitish extends minimally on to the tail-stalk, leaving the tail mainly dark.
Other details:
- in the facial colouration, the dark rostral spot is minimal in all individuals of Peters' gazelle; and
- whitish wraps so narrowly on to the front of the upper hindleg that it is hardly visible in profile.
Peters' gazelle
- is the form of its genus most closely resembling genus Gazella in colouration (e.g. see https://www.facebook.com/NikonIndia/posts/indian-gazelle-one-of-the-finest-posers-in-nature-throughyourlensimage-courtesy-/3607500265928157/), and
- can be regarded as a replacement for that genus beyond the southernmost limit of Gazella on the Horn of Africa (https://en.wikipedia.org/wiki/Horn_of_Africa).
However, Peters' gazelle remains larger-bodied than any form of Gazella.
Furthermore, Peters' gazelle
- has a tail slimmer and less demonstrative in its movements than in any species of Gazella,
- de-emphasises the dark flank-band to a degree unknown in Gazella, despite emphasising the pygal band (i.e. the dark vertical feature between the haunch and the whitish buttock), and
- has dark accentuation of the eye to a degree not seen in Gazella, by means of a malar stripe (https://binocularbase.com/what-is-a-malar-stripe/#:~:text=The%20malar%20stripe%20is%20a,this%20stripe%20got%20its%20name.).
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