Contribution to the knowledge of ticks (Acarina: Ixodidae) in Gabon

Few data are available on the distribution of tick species in Gabon. We report the results of a survey of ticks collected from wild and domestic animals, and in the environment, in several regions of Gabon. We identified four tick species for the first time in Gabon, namely Haemaphysalis paralaechi, Ixodes aulacodi, Rhipicephalus annulatus and Rhipicephalus simpsoni and we report 28 tick species for this country

However, the data are far from complete for most parts of central Africa.We therefore conducted a survey of specimens collected in several regions of Gabon, and updated the list of ticks (Acarida, Ixodidae) in this country.

MATERIALS AND METHODS
Sampling took place from October 2009 to December 2010.Ticks were collected by direct examination of animals and by the sledge method in the environment (Cornet et al. 1984).Wild animals were those captured by hunters for trade and consumption as bushmeat in villages.Domestic animals were freeroaming in villages.On bushmeat animals, ticks were collected within 12 to 72 hours after death.All specimens were preserved in 75 % ethanol until examination.
The mammal nomenclature was based on Wilson and Reeder (2005).

Collection sites
Ticks were collected at 64 sites distributed throughout Gabon (Figure 1

Amblyomma paulopunctatum Neumann, 1899
In Gabon, this species has previously been found in Libreville and Tchibanga (1930, Collection Brumpt Institut de Parasitologie, Faculté de Médecine de Paris, CBpt) on Potamochoerus porcus bush pigs.The Suidae family is the preferred host.

Amblyomma splendidum Giebel, 1877
This species is mainly found on the African buffaloes, Syncerus caffer nanus.It was first collected in Gabon in Cap Lopez, and later in Ngomo (Robinson, 1926), Lambaréné, Lastourville, Ndende and Tchibanga (Neumann, 1899).We collected adult and nymph stages of A. splendidum by sledge sampling on buffalo ponds in Lopé reserve.This species is probably widespread in Gabon, like its host species.It was occasionally found on Kobus ellipsiprymnus in the river Nyanga.

Amblyomma tholloni Neumann, 1899
This species is commonly found on elephants (Loxodonta africana).In Gabon, it has previously been found in Libreville and Tchibanga (1930, CBpt).We collected A. tholloni in Lopé from tree branches and by the sledge method.In Sebe, we also collected a male of this species from Atherurus africanus.

Amblyomma variegatum Fabricius, 1794
This species appears to have a broad range of hosts.It has previously been found by Rousselot (1953) and Moubamba (2006) in Libreville, Oyem, Mitzic, Mayumba and Franceville, on cattle and dogs (Moubamba, 2006).We found it on cattle in Franceville.

Amblyomma arcanum Karsch, 1879
This species was previously considered as Aponomma arcanum.Amblyomma arcanum feed on reptiles.It has been collected by Morel (1961)
Haemaphysalis paraleachi Camicas, Hoogstraal and El Kammah, 1983 We detected this species in Gabon for the first time.It was found only at adult stages on domestic dogs in Dienga.Interestingly, all dogs sampled were parasitized by this species, but no specimens of Rhipicephalus sanguineus were found.

Ixodes Latreille, 1795
Ixodes aulacodi Arthur, 1956 We detected this species in Gabon for the first time in Bighoundou were it was collected at adult and nymphal stage on his preferred host, the greater cane rat Thryonomys swinderianus.

Ixodes cumulatimpunctatus Schulze, 1943
This species was firstly collected in Gabon in previous studies in Tchibanga on domestic dog (Morel, 1964, CBpt).We found it on Cephalophus dorsalis and P. monticola in Hendje, Mandilou, Onkoua and Zambakaganga at adult and nymphal stage.Adult specimens were also collected on Atherurus africanus in Sebe, on Manis tricuspis in Abong awoum and on Potamochoerus porcus in Lolo 1.

Rhipicephalus annulatus Say, 1821
This species was previously considered as Boophilus annulatus.R. annulatus feed almost exclusively on domestic ungulates (especially cattle) and also on African buffaloes.We detected R. annulatus for the first time in Gabon on cattle in Franceville.Neumann, 1907 This species is considered to be a junior synonym of R. ziemanni by some authors (Guglielmone et al., 2009).This species was first found in Ngomo on cattle (Neumann, 1908; as R.cuneatus) and then in Tchibanga on Potamoechoerus porcus (1930, CBpt).Morel, 1965 This species is considered to be a junior synonym of R. pseudolongus by some authors (Guglielmone et al., 2009).In Gabon, adults of this species were first collected in Ndendé (Rousselot, 1953; as R. capensis and R. capensis longus).It was probably confused with Rhipicephalus pseudolongus or R. longus.R. cliffordi has been found on Potamoechoerus porcus in Tchibanga and on Syncerus caffer nanus in Ndendé (Morel, 1965a).Neumann, 1911 This species is commonly found on wild and domestic pigs.It was first detected in Samkita, Lambarené (1913, MNHN) and Tchibanga on Potamochoerus porcus (1930, CBpt).We also collected adult stages from P. porcus in Djounou, Omoy, Yoko, Guietsou and Lambaréné.

Rhipicephalus longus Neumann, 1907
This species is found on various wild and domestic ungulates and other mammals.In Gabon, it was first found in Franceville on domestic pigs (1926, CBpt) and in Tchibanga on dogs (1930, CBpt).

Rhipicephalus pseudolongus Santo Dias, 1953
This species is often confused with R. longus.We found adult specimens of R. pseudolongus on cattle in Franceville.

Rhipicephalus sanguineus Latreille, 1806
This common species is mainly associated with domestic dogs.It has been collected in Libreville on dogs (Morel and Vassiliades, 1963;Moubamba, 2006).We also found it, at all stages, on domestic dogs in Franceville.

Rhipicephalus simpsoni Nuttall, 1910
We found adult R. simpsoni, for the first time in Gabon, on the greater cane rat Thryonomys swinderianus in Bighoundou.Neumann, 1908 In Gabon, this species has only been described on domestic dogs in Tchibanga, 1930 CBpt).

CONCLUSION
This survey identified four tick species for the first time in Gabon, namely Haemaphysalis paralaechi, Ixodes aulacodi, Rhipicephalus annulatus and Rhipicephalus simpsoni.So far, 28 species of the Ixodidae ticks have been recorded in this country.In the central African region, 53 species Ixodidae tick have been reported in Cameroun (Morel and Mouchet 1965) and 46 in the Central African Republic (Cornet 1995).It is thus highly probable that more tick species are present in Gabon, particularly those belonging to the genus Rhipicephalus, which is the most diverse group of afrotropical ticks.No ticks of the genus Hyalomma have been reported, probably because they are mainly associated with arid tropical climates.However, they might possibly be present in savannas of southern Gabon.