@capracornelius @tandala @oviscanadensis_connerties @jeremygilmore @paradoxornithidae @beartracker @jacqueline_llerena @henrydelange @tonyrebelo @koosretief @justinhawthorne @ludwig_muller @happyasacupcake @marcelo_aranda @enricotosto96 @diegoalmendras @michaelweymann @fionahellmann
...continued from https://www.inaturalist.org/journal/milewski/58139-the-bambis-part-7-why-do-certain-genera-show-tropical-hues#
Grysboks (Raphicerus melanotis https://es.123rf.com/photo_39925015_a-rare-cape-grysbok-antelope-raphicerus-melanotis-south-africa.html and https://www.inaturalist.org/observations/72612861) and Raphicerus sharpei (https://www.shutterstock.com/image-photo/sharpes-grysbok-antelope-794728726 and https://www.alamy.com/stock-photo-sharpes-grysbok-31791328.html?imageid=8258088A-BE1C-47D2-B568-B4E03D47F25D&p=34420&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0 and https://www.shutterstock.com/image-photo/sharpes-grysbok-hiding-thick-green-undergrowth-2178590039) occur in the southern and southeastern parts of Africa.
Among all the ungulates of the world, these are among the best examples of thoroughly inconspicuous colouration, of a cryptic type (https://en.wikipedia.org/wiki/Crypsis).
Grysboks are nocturnal and non-gregarious, and depend on shrubby vegetation for cover.
This means that the colouration is so plain and featureless that the figures blend extremely well into the environment (https://www.inaturalist.org/observations/11178739 and https://www.inaturalist.org/observations/48569125 and https://commons.wikimedia.org/wiki/File:Sharpe%27s_Grysbok.jpg and https://www.shutterstock.com/image-photo/sharps-grysbok-kruger-1083039092).
Even more so, when one considers that any differentiation in hues (rufous ground-colour vs grey on the posterior surface of the ears, https://www.inaturalist.org/observations/68999756) are probably invisible in the eyes of the relevant animals (i.e. grysboks themselves, and the Carnivora that are their main predators).
On one hand, this seems to make grysboks the simplest - and least interesting - of ungulates for further investigation, in terms of adaptive colouration.
However, I take a more curious approach.
What the simplicity of the colouration of grysboks means is that we have an opportunity to clarify any small-scale features that do not conform to the overall plainness.
These anomalous features (*asterisk indicates individual variation) are
whitish of variable extent on the throat (https://www.africahunting.com/media/cape-grysbok-tiny-ten-full-mount-taxidermy.50587/
and https://www.flickr.com/photos/brinksview/24997270338 and https://www.inaturalist.org/observations/10935808 and https://m.facebook.com/BLphotography/photos/a-beautiful-sharpes-grysbok-which-is-the-smallest-antelope-found-in-south-luangw/10156401808757698/ and https://www.shutterstock.com/image-photo/sharpe-grysbok-kruger-national-park-south-1157443249 and https://www.istockphoto.com/photo/sharps-grysbok-antelope-in-front-of-a-thorn-bush-gm693678254-128137499?phrase=grysbok)
BODY
Many species of mammals have grizzled/speckled pelage, in which each hair is graduated in colour from the base to the tip (https://en.wikipedia.org/wiki/Fur#/media/File:Down_Awn_and_guard_hairs_of_cat_2012_11_13_9203r.JPG).
However, in grysboks the form of grizzing is, as far as I know, unique among ruminants. This is because each hair is homogeneous in colour, but a minor percentage of the hairs are whitish.
Countershading (https://en.wikipedia.org/wiki/Countershading) is better-developed in R. sharpei than in R. melanotis. This is unsurprising, based on similar latitudinal patterns in various other ruminants (https://www.inaturalist.org/journal/milewski/53696-a-succinct-photo-guide-to-subspecies-of-the-bush-duiker#).
FACE, HEAD and EARS
The face of grysboks is not plain-coloured. One of the best illustrations of the pattern can be found by scrolling in https://www.edwardselfephotosafaris.com/newsp27.html.
All ruminants with a bare rhinarium have the nose dark-pigmented. However, the following of Cephalophus shows that the colouration of the face can otherwise be plain in small-bodied ruminants: https://www.dreamstime.com/stock-photo-duiker-close-up-detail-small-west-african-antelope-image75691614.
My interpretation is as follows:
The various markings on the face have dual functions at different scales.
When viewed from some distance, they amount collectively to a form of disruptive colouration, 'camouflaging' the head by disrupting its shape.
However, the same markings can also function, at close range, for social communication, e.g. aiding individual recognition.
Grysboks differ from their congener, Raphicerus campestris, in that the whitish pelage adjacent to the eye (https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=333179556) has been eclipsed.
I suspect that this has occurred not by means of any darkening of the hairs, but rather by a thinning of the pelage, exposing the blackish skin (https://www.redbubble.com/people/mags/works/7400304-the-tiny-shy-scarce-sharpe-s-grysbok-raphicerus-sharpei-kruger-national-park).
The ear pinna is large in all spp. of Raphicerus, probably for thermoregulation as much as hearing.
However, it is puzzling that the hair-curtains, which open and close ostensibly in reaction to temperature, are not a brownish colour, which would make the front-of-ear inconspicuously plain.
Instead, the hair-curtains are pale enough to be conspicuous at distances potentially relevant to scanning predators (https://www.inaturalist.org/observations/21208569 and https://www.inaturalist.org/observations/7026104).
This puzzle deserves further thought, as does the individually variable paleness on the front of the neck.
The following show the pale hair-curtains on front-of-ear
The paleness of the lower lip and chin is poorly explained by countershading.
I interpret the colouration around the mouth in both spp. to be a buccal semet (https://www.inaturalist.org/observations/11263147 and https://www.alamy.com/sharpes-grysbok-raphicerus-sharpei-south-africa-mpumalanga-kruger-national-park-image255383147.html?imageid=B2DB3495-B84D-45B8-93F0-CADC61B7296C&p=853443&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0 and https://www.alamy.com/stock-photo-portrait-of-sharpes-grysbok-raphicerus-sharpei-in-the-bush-the-photo-33096574.html?imageid=097746CA-48F5-40A6-8578-BFE7EBA82631&p=60598&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0). Please note, in the following view (https://www.inaturalist.org/observations/13582069), that the lower lip and adjacent pelage is the only part of the figure that is whitish.
This small-scale pattern may possibly be more conspicuous in ultraviolet than in the range of wavelengths visible in human eyes.
FEET
The following is possibly the most unexpected of my findings in this Post.
Raphicerus sharpei, in at least some individuals, has anomalously pale feet, which possibly function as a pedal flag. I have, as yet, no explanation for why there is no such feature in either R. melanotis or R. campestris.
However, R. sharpei also happens to differ from R. melanotis in
So, what emerges is that one of the main differences between the two spp. of grysboks is in the feet, including their anatomy, colouration, and action in producing an audial and possibly visual signal in an anti-predator context.
to be continued in https://www.inaturalist.org/journal/milewski/70293-the-bambis-part-9-bleezes-flags-and-semets-in-the-bovid-genus-raphicerus#...
Σχόλια
https://www.krugerpark.co.za/africa_cape_grysbok.html
Raphicerus campestris mislabelled as grysbok:
https://www.shutterstock.com/image-photo/cape-grysbok-184337792
https://www.shutterstock.com/image-photo/cape-grysbok-163036748
https://www.dreamstime.com/sharpe-s-grysbok-southern-african-savanna-sharpe-s-grysbok-image133587913
https://www.shutterstock.com/image-photo/sharpe-grysbok-kruger-national-park-south-1153459057
https://www.shutterstock.com/image-photo/sharpes-grysbok-386409091
https://www.krugerpark.co.za/africa_sharpes_grysbok.html
The following of Raphicerus sharpei show the size of the tail particularly clearly:
https://www.alamy.com/stock-photo-sharpes-grysbok-raphicerus-sharpei-kruger-national-park-south-africa-25912072.html?imageid=90E236B0-6EFB-4A4F-AFF4-96768969C3BF&p=74587&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0
https://www.shutterstock.com/image-photo/grysbok-antelope-seen-on-safari-south-1932461942
https://www.zoochat.com/community/threads/ungulate-taxonomy-revisited-the-evidence-for-the-splits-of-g-g.467230/page-3#post-1060823
RAPHICERUS CAMPESTRIS:
Front-of-ear with pale hair-curtains closed:
https://stock.adobe.com/search?k=steenbok&asset_id=505717039
https://stock.adobe.com/search?k=steenbok&asset_id=43651464
https://stock.adobe.com/search?k=steenbok&asset_id=83926648
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=310160454
Front-of-ear with pale hair-curtains partly open:
https://stock.adobe.com/search?k=steenbok&asset_id=210184395
Front-of-ear with pale hair-curtains fully open:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=132701922
Buccal semet:
https://stock.adobe.com/search?k=steenbok&asset_id=396571930
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=361471688
The following show that the placement of the orbits and eyes differs among the three spp. belonging to the genus Raphicerus, in accordance with the openness of the vegetation they typically inhabit.
The orbits and eyes are most lateral in Raphicerus campestris, least lateral in R. melanotis, and intermediate in R. sharpei.
Raphicerus campestris:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=130106010
https://www.inaturalist.org/observations/70248705
Raphicerus melanotis:
https://www.dreamstime.com/royalty-free-stock-photos-southern-grysbok-image15691838
Scroll in http://cameratrap.mywild.co.za/2018/02/paarl-data-two-antelope-and-bird.html
Raphicerus sharpei:
https://www.istockphoto.com/photo/sharpes-grysbok-hiding-in-the-thick-green-undergrowth-gm1408808817-459560210?phrase=grysbok
Jonathan Kingdon has exaggerated the colouration of the buttocks, in his painting of Raphicerus sharpei:
https://www.researchgate.net/publication/311546836_Raphicerus_sharpei_Sharpe%27s_Grysbok
Compare:
https://upload.wikimedia.org/wikipedia/commons/1/17/Sharpe%27s_Grysbok_%28Raphicerus_sharpei%29_female_%2811802609134%29.jpg
I am puzzled by the bareness of the front-of-ear in this specimen of Raphicerus melanotis:
https://www.zoochat.com/community/media/cape-or-southern-grysbok-raphicerus-melanotis.486198/
Raphicerus campestris differs from grysboks in having white inner buttocks:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=441156073
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=526322906
These can be further exposed by flaring (piloerection) of the adjacent brownish pelage of the outer buttocks:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=441230341
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=180230559
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=180230715
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=466446514
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=476713200
The following shows the complexity of the colouration on the mandible in Raphicerus campestris:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=378593532
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=378593486
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=378593613
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=378593575
The following shows that the bare skin of the udder is blackish in Raphicerus campestris:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=510372750
I have not detected any auricular semet in any species of Raphicerus. However, the following, of Raphicerus melanotis, shows a slight tendency to pale at the bases of the ear pinnae:
https://www.inaturalist.org/observations/71202515
@mileswki
I believe it to be a mature female from the Axis porcinus complex.
The following (https://www.capetownetc.com/cape-town/baby-grysbok-spotted-on-camera/) shows several aspects of Raphicerus melanotis.
The colouration is identical in adult and infant.
The paleness of the lateral surface of the mandible is anomalous, relative to the principle of countershading.
The false hooves are so small, in this species, that they are barely visible even in this exceptionally close-up photo.
https://www.africa-and-beyond.co.uk/attractions/the-sharpes-grysbok-of-congo/
A difference between Raphicerus campestris campestris (https://www.inaturalist.org/observations/64700091) and coexisting Raphicerus melanotis (https://www.inaturalist.org/observations/67016057) is that only the former folds its ear pinnae back and down when 'freezing' in mild alarm, in low vegetation.
The ear pinnae of the two species are similar in size and colouration. However, folding the ears is adaptive in R. campestris is adaptive because this species is diurnally active, and prefers vegetation too low to hide the standing figure.
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