Verheyen-Ducker
| Verheyen-Ducker | ||||||||||||
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| Philantomba walteri | ||||||||||||
| Colyn , Hulselmans , Sonet , Oudé , de Winter , Natta , Nagy & Verheyen , 2010 |
The Verheyen duiker ( Philantomba walteri ) is a species of duiker from the genus Philantomba . It is common in the tropical rainforests of western Africa and includes the once eastern group of the Maxwell duckers , to which it is closely related. However, due to deviating external and skeletal anatomical features and genetic differences compared to the western population, it was raised to a separate species in 2010. Little is known about the way of life of the Verheyen ducker. The stock is considered endangered.
features
Habitus
The Verheyen duiker is about the size of the Maxwell duiker ( Philantomba maxwelli ), but it is characterized by a slimmer silhouette. Its head-trunk length is 55 to 75 cm, the tail is at least 15 cm in length on average longer than the Maxwell duiker and significantly longer than the blue duiker. The weight is 6 to 12 kg. The fur color of the trunk is slate gray or brown, throat, chest and belly are tinted a little lighter. In contrast to the Congo blue duiker ( Philantomba congica ), there is no sharp break between the darker croup and the lighter thighs and lower legs. The tail shows white fringes at the tufted end. Hair that runs conspicuously against the grain appears on the neck. The head is smaller and less massive compared to the Maxwell Ducker, but it has its dark mouth and forehead. Above the nose, a lighter stripe runs laterally from about the height of the eyes to the base of the horn. In addition, the pre-eye glands stand out with a distinctive stripe. On the head there is a small head of dark hair. The horns end pointed and, unlike the Maxwell duiker, are almost always developed in both sexes. In the males they are 4.5 to 5.5 cm long and have a strong ring formation at the base. A horn measured in a female was almost 4 cm long.
Skull features
The skull length is 13.4 to 14.5 cm, the greatest width between the zygomatic arches is 6.2 to 6.6 cm. Compared to the Maxwell Ducker, the skull is on average smaller and noticeably lower, and the nasal bone is much less drawn in laterally. The Verheyen Ducker shows a slight sexual dimorphism based on the size of the skull: Males have a slightly larger skull than females, but the rostrum is shorter and wider in the latter . The tooth formula is :, thus a total of 32 teeth are formed in the dentition. The length of the upper row of teeth varies from 3.7 to 4.4 cm.
distribution
The Verheyen Ducker occurs in West Africa in Nigeria west of the Cross River via Benin to Togo . Possibly the distribution area extends in the west to Ghana to the river Volta . It prefers to inhabit tropical rainforests or patches of forest in savannah areas . Part of the area belongs to the Dahomey Gap in Benin and Togo, a natural barrier between the eastern and western rainforest areas ( Eastern Guinean Forest and Western Guinean Forest ). There are few endemic species in this landscape , with most of the mammals found being part of the richer western and eastern rainforest blocks. As a result, the landscape has attracted little interest from biologists in the past.
Way of life
The Verheyen ducker's way of life is practically unknown, but it is presumably similar to that of the Maxwell ducker. In Nigeria, juveniles have been spotted during the dry season from January to March and August to September.
Systematics
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Internal systematics of Philantomba according to Johnston et al. 2012
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The Verheyen duiker is a species of the genus Philantomba within the family of the horned bearers (Bovidae). Philantomba belongs to the tribe of duikers (Cephalophini) within the horn-bearers , to which Sylvicapra and Cephalophus are also included. The duikers form a group of mostly smaller to medium-sized representatives of the horn-bearers, which are characterized by a compact build. They occur endemically in Africa and predominantly inhabit wooded habitats . The genus Sylvicapra , whose representatives tend to prefer savannah landscapes , is an exception .
The genus Philantomba includes the dwarf duiker, the smallest representatives of the tribe. It was partially seen as a subgenus of Cephalophus in the 20th century . In a 2001 study, Peter Grubb and Colin Peter Groves recognized Philantomba as a separate genus. According to her morphological studies, she stood on the side of Sylvicapra . In the same year one was molecular genetic study published that for Philantomba a sister group relationship to Cephalophus - Sylvicapra revealed group. Another genetic test from 2012 confirmed the result of the previous one. As a result, the dwarf duikers form their own genus, which split off from the other duikers in the late Miocene around 7.55 million years ago. Originally only two species within the genus Philantomba were recognized with the Maxwell duiker ( Philantomba maxwelli ) and the blue duiker ( Philantomba monticola ) . With the Verheyen Ducker, a third species could be described at the beginning of the 21st century. A 2011 revision of the hornbeams, also carried out by Groves and Grubb, split the blue duiker into two groups of closely related species, one with gray legs and one with red legs.
discovery
Already in 2005, Grubb and Groves pointed out in a revision of the duikers that the populations of the Maxwell duiker in western Africa show striking differences between the individuals in the western and eastern range. According to their investigations, not only did the size increase significantly from east to west, there were also deviations in the color of the fur, which separated them from a western group from an eastern group. In the following period, the Projet d'Aménagement des Massifs Forestiers (PAMF) d'Agoua, de Wari-Maro et des Monts Kouffé collected animals from local hunters as well as bushmeat markets . This resulted in a total of around three dozen individuals from eight sites in Benin, Togo and Nigeria. The analyzes carried out confirmed the observations made by Grubb and Groves. In addition, genetic analyzes were carried out, including the Maxwell and the blue ducker . They found that the western and eastern populations of the Maxwell ducker are each monophyletic . As a result, the eastern group was spun off as a separate species from the Maxwell Ducker and received the scientific name Philantomba walteri ; the first description published by Marc Colyn and fellow researchers in 2010. The holotype represents a not fully grown female (specimen number RMCA A7.027M0001), which was collected in January 2006. The type region is Igbere in the Forêt Protégée de Wari-Maro in Benin, which is about 328 m above sea level. The species addition walteri honors Walter Verheyen for his services to research into the African animal world.
Threat and protection
The Verheyen-Ducker is currently listed by the IUCN in the category “ data deficient ” . The nature conservation organization justifies this with the fact that too few individuals are known, there are no observations in the wild and thus no precise delineations of the distribution area and no information on the population size can be made. According to the first description, the stocks in Togo and Nigeria are to be regarded as endangered, to a certain extent also those of Benin. The animals are hunted regularly and offered for bushmeat at local markets .
literature
- Colin P. Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , p. 753
- Marc Colyn, Jan Hulselmans, Gontran Sonet, Pascal Oudé, Jan de Winter, Armand Natta, Zoltán Tamás Nagy and Eric Verheyen: Discovery of a new duiker species (Bovidae: Cephalophinae) from the Dahomey Gap, West Africa. Zootaxa 2637, 2010, pp. 1-30
Individual evidence
- ↑ a b c d e Marc Colyn, Jan Hulselmans, Gontran Sonet, Pascal Oudé, Jan de Winter, Armand Natta, Zoltán Tamás Nagy and Eric Verheyen: Discovery of a new duiker species (Bovidae: Cephalophinae) from the Dahomey Gap, West Africa . Zootaxa 2637, 2010, pp. 1-30
- ↑ a b c d e Colin P. Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , p. 753
- ↑ a b c Anne R Johnston and Nicola M Anthony: A multi-locus species phylogeny of African forest duikers in the subfamily Cephalophinae: evidence for a recent radiation in the Pleistocene. BMC Evolutionary Biology, 12, 2012, p. 120 ( [1] )
- ↑ Bettine Jansen van Vuuren and Terence J. Robinson: Retrieval of Four Adaptive Lineages in Duiker Antelope: Evidence from Mitochondrial DNA Sequences and Fluorescence in Situ Hybridization. Molecular Phylogenetics and Evolution 20 (3), 2001, pp. 409-425
- ↑ Colin P. Groves and Peter Grubb: Ungulate taxonomy. Johns Hopkins University Press, Baltimore 2011, ISBN 978-1-4214-0093-8 , pp. 266-269
- ^ IUCN SSC Antelope Specialist Group: Philantomba walteri. The IUCN Red List of Threatened Species 2016. e.T88418111A88418148 ( [2] ); last accessed on October 4, 2016
Web links
- Philantomba walteri in the endangered Red List species the IUCN 2016 Posted by: IUCN SSC Antelope Specialist Group, 2016. Accessed on 10/04/2016.