Tragelaphini


The tribe Tragelaphini, or the spiral-horned antelopes, are bovines that are endemic to sub-Saharan Africa. These include the bushbucks, kudus, and the elands. The scientific name is in reference to the mythical creature the tragelaph, a Chimera with the body of a stag and the head of a goat. They are medium-to-large, tall, long-legged antelopes characterized by their iconic twisted horns and striking pelage coloration patterns.
Despite being among the largest species of antelope, they are actually more closely related to cattle, and together along with a few apparent Asiatic species belong to the subfamily Bovinae. While the group's evolutionary history occurred in Africa, there have been fossil species that have been found in Eurasia. The number of genera and species is debated as some consider there to be one or two genera with nine species, while others consider there to be five genera and 25 species. In general, spiral-horned antelopes can be roughly divided into two groups: robust forms and gracile forms.
Spiral-horned antelopes are browsers, found in a wide variety of environments both arid and humid, including semi-deserts, savannas, rainforests and mountains. In all these environments, however, they prefer to live in dense bush or thicket, which offer concealment from their natural predators. Considered among the most beautiful and charismatic bovids, the various species of spiral-horned antelopes are popular in zoos and game reserves. The two eland species have been ranched as alternatives to cattle, being hardy in extreme environments, relatively placid in character, and nutritionally superior as a meat source.

Etymology

The tribe name "Tragelaphini" was published as a subfamily by British zoologist Edward Blyth in 1863, and was downgraded to tribe by Russian zoologist Vladimir Sokolov in 1953. It refers to the mythical tragelaph which was imagined to be half-goat, half-stag. The root words come from Greek, with τράγος meaning "male goat" and έλαφος meaning "stag". The suffix "–ini" refers to their ranking as a tribe.
The alternative name "Strepsicerotini" was published by another British zoologist John Edward Gray as "Strepsiceriae" earlier in 1846. It comes from Greek with στρεπτός meaning "twisted" and κέρατος meaning "horn", referring to the shape of this group's horns. However, "Strepsiceriae" had the incorrect prefix and suffix, which this was corrected to "Strepsicerotini" in 1945 by American paleontologist George Gaylord Simpson. While the name "Strepsicerotini" was published first, most scientists used the latter name "Tragelaphini" as it is more widely used.

Systematics

Placement within Bovinae

The spiral-horned antelopes belong to the subfamily Bovinae which also includes oxen of the tribe Bovini and two aberrant species of Asian antelope, the four-horned antelope and the nilgai which belong to the tribe Boselaphini. The relationship between the tribes varies in research concerning their phylogeny. Most molecular research supports a Bovini and Tragelaphini subclade of Bovinae. There are also some morphological support for oxen being the closet living relatives to the spiral-horned antelopes, most notably both groups have horn cores with a pedicle.
There has been a few studies which have supported alternate arrangements, one being a sister relationship between the nilgai and the spiral-horned antelopes. Historically, the nilgai was classified as a tragelaphine by some scientists. Benirschke et al. worked on karyotypes with the lesser kudu and found them to share with the nilgai an X chromosome fused with autosome 14. Another study that analyzed the COII gene found the nilgai and lesser kudu being sister species. The majority of other molecular and morphological work do not support the placement of the nilgai in Tragelaphini, as it contradicts with their data and results.

The fossil record

Tragelaphini has diverged from their closet sister taxon for the last 15 to 18 million years. It was once thought that spiral-horned antelopes were uniquely African, but there have been Eurasian fossils found in Greece and the Caucasus. Kostopoulos and Koufos have described Pheraios chryssomallos from fossils found in the Turolian locality of Thessaly, Greece. The authors have found cladistic support of P. chryssomallos being the basal most tragelaphin based on 46 cranial features. This suggests that the ancestor of all known species of spiral-horned antelope must have originated in Europe during the late Miocene. The eastern European genus Pontoceros is another example, although this animal has been found in early Pleistocene beds of the Mygdonia basin. This suggests that spiral-horned antelopes have emigrated from Africa and into Eurasia during a latter period in their evolutionary history. In addition, undescribed fossils found in South Asia could be related to spiral-horned antelopes.
Fossils from Africa have been recovered in places such as Olduvai Gorge in Tanzania, but they are sometimes consist of fragmented pieces of leg bone and horn. The oldest known of these species is Tragelaphus moroitu which has been found in the late Miocene to early Pliocene deposits of the Asa Koma, Kuseralee and the Middle Awash deposits in the horn of Africa. Similar in appearance to the nyala, T. moroitu was a small antelope and has primitive characteristics in the horn core, making it the most primitive known species of spiral-horn antelope in Africa. The evolution of spiral-horned antelopes based on the abundance of fossils shows they were among the most common species of antelope in Africa, and as climatic changes have occurred throughout their evolution, they have undergone faunal turnovers and adapting to new environments.
Below is the list of fossil species that have been described so far listed in alphabetical order:
  • Tribe Tragelaphini Blyth, 1863 sensu Sokolov, 1953
  • * Genus †Pheraios Kostopoulo & Koufos, 2006
  • ** †Pheraios chryssomallos Kostopoulo & Koufos, 2006
  • * Genus †Pontoceros Vereshchagin et al., 1971
  • ** †Pontoceros surprine Vekua, 2012
  • ** †Pontoceros ambiguus Vereshchagin et al., 1971
  • * Genus Taurotragus Wagner, 1855
  • ** †Taurotragus arkelli Leakey, 1965
  • ** †Taurotragus maroccanus Arambourg, 1939
  • * Genus Tragelaphus de Blainville, 1816
  • ** †Tragelaphus algericus Geraads, 1981
  • ** †Tragelaphus gaudryi Thomas 1884
  • ** †Tragelaphus kyaloae Harris, 1991
  • ** †Tragelaphus lockwoodi Reed & Bibi, 2011
  • ** †Tragelaphus moroitu Haile-Selassie et al., 2009
  • ** †Tragelaphus nakuae Arambourg, 1941
  • ** †Tragelaphus nkondoensis Geraads & Thomas, 1994
  • ** †Tragelaphus pricei Wells & Cooke, 1956
  • ** †Tragelaphus rastafari Bibi, 2011
  • ** †Tragelaphus saraitu Geraads et al., 2009

    Taxonomy

Traditionally the tribe was divided into two genera and seven species as shown below:
However recent molecular studies have shown a different arrangement. According to the molecular work on the nuclear DNA and mitochondrial DNA, the lesser kudu and the nyala are the basal most living species. Then around 10 million years ago there was a split between forest-dwelling, gracile species and larger, open-plains species. This renders Tragelaphus paraphyletic in respect to Taurotragus, which either means to make the latter genus into a junior synonym of the former genus or split Tragelaphus into several genera to maintain Taurotragus. In a 2011 large scale taxonomic reorganisation of ungulates by Groves and Grubb, they recognised new cryptic species, and split the traditional species into several geographical species. This was based on morphological comparisons between the species and defined species based on phylogenetic species concept. Groves and Grubb furthermore establish of several new genera in light of Tragelaphus being paraphyletic. They have a slight different arrangement of the species in Tragelaphus ''sensu stricto than suggested by genetics. Other scientists have mixed reactions to this proposal, with some preferring the traditional number of species to be seven and others preferring the new taxonomy from Groves and Grubb.
Below is the alternative taxonomy based on Groves and Grubb, with species and subspecies names following Castelló from Bovids of the World:
  • Tribe Tragelaphini Blyth, 1863 sensu Sokolov, 1953 – spiral-horned antelopes
  • * Genus Ammelaphus Heller, 1912 – lesser kudus
  • ** Ammelaphus imberbis – northern lesser kudu
  • ** Ammelaphus australis Heller, 1913 – southern lesser kudu
  • * Genus Nyala Heller, 1912
  • ** Nyala angasii – lowland nyala
  • * Genus Taurotragus Wagner, 1855 – elands
  • ** Taurotragus derbianus – giant eland
  • *** Taurotragus derbianus gigas Heuglin, 1863 – eastern giant eland
  • *** Taurotragus derbianus derbianus – western giant eland
  • ** Taurotragus oryx – common eland
  • *** Taurotragus oryx ivingstonii Sclater, 1864 – Livingstone's eland
  • *** Taurotragus oryx pattersonianus Lydekker, 1906 – East African eland
  • *** Taurotragus oryx oryx – Cape eland
  • * Genus Strepsiceros Hamilton Smith, 1827 – greater kudus
  • ** Strepsiceros strepsiceros – Cape greater kudu
  • ** Strepsiceros zambesiensis – Zambezi greater kudu
  • ** Strepsiceros chora – northern greater kudu
  • ** Strepsiceros cottoni – western greater kudu
  • * Genus Tragelaphus de Blainville, 1816
  • ** Tragelaphus scriptus – western bushbuck
  • *** Tragelaphus phaleratus – central bushbuck
  • *** Tragelaphus bor Heuglin, 1877 – Nile bushbuck
  • *** Tragelaphus decula – Abyssinian bushbuck
  • *** Tragelaphus meneliki Neumann, 1902 – Menelik's bushbuck
  • *** Tragelaphus fasciatus Pocock, 1900 – eastern coastal bushbuck
  • *** Tragelaphus ornatus Pocock, 1900 – Chobe bushbuck
  • *** Tragelaphus sylvaticus – Cape bushbuck
  • ** Tragelaphus buxtoni – mountain nyala
  • ** Tragelaphus euryceros – bongo
  • *** Tragelaphus euryceros isaaci – mountain bongo
  • *** Tragelaphus euryceros euryceros – lowland bongo
  • ** Tragelaphus spekii group Speke, 1863 – sitatungas
  • *** Tragelaphus spekii Speke, 1863 – East African sitatunga
  • *** Tragelaphus sylvestris – Nkosi Island sitatunga
  • *** Tragelaphus larkenii – Nile sitatunga
  • *** Tragelaphus ugallae Matschie, 1913 – Tanzanian sitatunga
  • *** Tragelaphus gratus Sclater, 1880 – western sitatunga
  • *** Tragelaphus selousi'' Rothschild, 1898 – Zambezi sitatunga