First Record of an Epizoic Laboulbenia (Fungi: Laboulbeniales) on Ants (Hymenoptera: Formicidae) in Africa

Laboulbeniales is an order of ascomycetous fungi consisting of over 2000 species that have obligate association with arthropods, mostly insects, especially Coleoptera and Diptera, and on a few ant species, mites, thrips and millipedes (Tavares, 1985). Those fungi show a rather high level of host specificity. Their study remains in a challenging interface, between entomologists and mycologists and, consequently, clearly belong in the domain of a very few specialists in the world. Ants are known to harbor six species of Laboulbeniales: two species of the genus Rickia Cavara (on Myrmica Latreille or Messor Forel hosts), one Dimorphomyces Thaxter (on Nylanderia Emery) and three species of Laboulbenia Thaxter (on Camponotus Mayr, Lasius Fabricius, Formica Linnaeus, Polyergus Latreille, Myrmecocystus Wesmael, Prenolepis Mayr, Eciton Latreille). The global database of published antAbstract The first ant-Laboulbenial interaction in Africa is recorded. The fungus Laboulbenia camponoti Batra was detected over the body of workers Camponotus oasium Forel collected in Senegal. This is a huge range extension of its Eurasian previously known distribution, to the Afrotropical region. We present the updated global database for L. camponoti. Sociobiology An international journal on social insects


Introduction
Laboulbeniales is an order of ascomycetous fungi consisting of over 2000 species that have obligate association with arthropods, mostly insects, especially Coleoptera and Diptera, and on a few ant species, mites, thrips and millipedes (Tavares, 1985).Those fungi show a rather high level of host specificity.Their study remains in a challenging interface, between entomologists and mycologists and, consequently, clearly belong in the domain of a very few specialists in the world.
In the splendid work on the Ants of the Congo Basin (Wheeler, 1922), Bequaert writes about general ant-fungus relationships, and mentions Laboulbeniales noting "... they are inconspicuous and, when examined in situ on the host insect, appear in general like minute, usually dark-colored or yellowish bristles or bushy hairs, projecting from its chitinous integument either singly or in pairs, more commonly scattered, but often densely crowded over certain areas on which they form a furry coating.".The thallus attaches to the insect cuticle with a darkened foot.There are no penetrating hyphae or rhizoids into the ant body cavity in Laboulbenia formicarum Thaxter and L. camponoti Batra, or Rickia wasmannii Cavara and R. lenoirii Santamaria (Tragust et al., 2016).Therefore, the energy source(s) for growing and reproducing in ant-Laboulbeniales is unknown.This is an intriguing and fundamental issue to unravel in the biology of Laboulbeniales.

Material and Methods
The Camponotus sample was collected during a general ant sampling done close to the N-1 road in Senegal (14º6.11'N15º41.12'W).The habitat was an open Savannah, mainly agricultural, with scattered Acaciae trees.According to Tappan et al. (2004), the zone belongs to the West Central Agricultural Region close to the Saloum Agricultural Region.
Several mature and immature thalli were scratched off the third leg of one Camponotus worker.Permanent slides were prepared following previously described methods (Benjamin, 1971) and are kept in the BCB Mycotheca of Universitat Autònoma de Barcelona (BCB-slides).Ant specimens with attached fungi are kept in the private collections of K.G. and X.E.Photomicrographs were made with a Jenoptik ProgRes 10 Plus digital camera on a Leica DMR microscope equipped with differential interference contrast optics (DIC).Images were processed with Photoshop CS5 software and Dpx View Pro for its included feature of extended focus function.Macroscopic images were taken using a Nikon CoolPix S3600 and a Nikon binocular.Retouched with Microsoft Office Picture Manager.The map was done using CARTO Builder.

Results
Camponotus ants were found inside an abandoned termite nest under an acacia tree.Six workers were collected: -Three minor workers of Camponotus oasium Forel were detected with Laboulbenia camponoti thalli (Fig 1) over nearly all body parts (clypeus, eyes, scape, mesosoma, gaster and legs (Fig 2).Small black spots, the point of insertion of the thallus, contrasting with the yellow integument, were also abundant at the gula and coxae but no thalli were present or had developed, likely because of the frequent frictional forces those body parts bear.-Another two recently hatched workers had signs of early infestation, as immature thalli were developed only in the mesoand/or metatibiae, but the insertion points were not so developed and the general aspect is that of long, twisted white setae.

Discussion
The discovery of L. formicarum on C. (Tanaemyrmex) oasium is the first mention of any ant-Laboulbenial in Africa.At its description, this fungus was described from India, from the Indomalayan region.Later it was recorded from Europe, from the Palaearctic region.Now it is recorded from the Afrotropical region, separated by the Sahara from the Palaearctic.This is a nice example that poor research about the distribution of a species can be misleading about its area.
All African Camponotus, especially those belonging in the subgenus Tanaemyrmex, are candidates to harbour L. camponoti.A rough appraisal of the number of Tanaemyrmex species according to Emery (1925) and Wheeler (1922;as subgenus Myrmoturba Forel, 1912) is >130 in Africa south of Sahara.Thus, there are many possible hosts to search for L. camponoti.
Other ant genera in the subfamilies Formicinae, Dorylinae, Myrmicinae might be also infected with Laboulbeniales.For a summary of worldwide knowledge of ant-Laboulbenial interactions, see Santamaria and Espadaler (2015: Table 2 and Fig 2).
The enormous range of the known localities for L. camponoti (some ten thousand km from Delhi (India) to Dakar (Senegal) (Fig 3) fits well the notion that, among Fungi, those that are parasites on animals tend to have more wide-ranging geographical distribution than all other soil fungi functional groups (Tedersoo et al., 2014).One interesting future aim would be to compare the genetics of the different populations from the various regions.
The majority of data concerning the small group of ant-infesting Laboulbeniales come from Europe and North-America.Meso-and South America have four registers and Asia has a few examples restrained to the Delhi region (India).Nothing is recorded from the Australian region or from the enormous extensions between Japan and the Ural Mountains, Arabian Peninsula and Indonesia.The absence of data for ant-Laboulbeniales in the Australian region and Asia (Santamaria & Espadaler (2015: Fig 2)  We request the attention of entomologists dealing with African fauna, towards those small and interesting epizoic fungi.Our finding suggests that L. camponoti may be more widespread geographically than previously thought.One positive circumstance for the study of Laboulbeniales is the possibility of its detection either in alcohol-preserved or in dry-preserved specimens, also from rather old collections, rendering a new value to Museum collections (Suarez & Tsutsui, 2004).We cannot but expect a growth of information about the ant-Laboulbeniales interaction in Africa, if proper attention is dedicated to those epizoic fungi on ants.

Fig 2 .
Fig 2. Different views of Laboulbenia.camponotiBatra on the legs of Camponotus oasium Forel.SENEGAL: Kaolack, road between Birkelane and Kaffrine.Mature thalli show a darkened body; immature thalli are still hyaline and have an uninflated perithecium.A) Mature, blackish thalli on the third leg tibia.B) Immature specimens at the proximal end of second tibia.C) One fully mature and one nearly mature thallus on the third tibia.

Table 1 .
calls for a geographically focused consideration.World records of Laboulbenia camponoti Batra.Updated to February, 2017.All specific host identifications belong in the subgenus Tanaemyrmex Ashmead.