Mycosphere
Dictyostelid cellular slime moulds from Africa
Cavender JC1, Landolt JC2, Ndiritu GG3, Stephenson SL4*
1Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701 – [email protected] 2Department of Biology, Shepherd University, Shepherdstown, West Virginia 25443 – [email protected] 3Department of Biological Sciences, University of Arkansas, Fayetteville, 72701, USA and Centre for Biodiversity, National Museums of Kenya. 40658 00100 Nairobi, Kenya – [email protected] 4Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701 – [email protected]
Cavender JC, Landolt JC, Ndiritu GG, Stephenson SL. 2010 – Dictyostelid cellular slime moulds from Africa. Mycosphere 1(2), 147-152.
Dictyostelid cellular slime moulds (dictyostelids) are an understudied group in Africa, but several recent surveys carried out in the context of a Planetary Biodiversity Inventory project funded by the National Science Foundation of the United States have added a considerable number of new records from several areas of the continent. Since Edgar Olive isolated Polysphondylium pallidum from a sample of dung collected in Liberia at some point during the period between 1897 and 1900, at least 25 species of dictyostelids have been documented for continental Africa and about the same number for the island of Madagascar. These totals include an appreciable number of forms that appear to be new to science. Most of what is now known about the dictyostelids of continental Africa has been derived from study sites in East Africa and South Africa. Only limited data exist for West Africa and Central Africa, and we are aware of records of only two species of dictyostelids from all of North Africa.
Key words – Dictyostelium – distribution – Madagascar – Polysphondylium
Article Information Received 8 April 2010 Accepted 10 May 2010 Published online 19 July 2010 *Corresponding author: Stephenson SL – e-mail – [email protected]
Introduction deserts (Benson & Mahoney 1977), and both Dictyostelid cellular slime moulds alpine (Cavender 1983) and arctic (Cavender (dictyostelids) are single-celled, eukaryotic, 1978, Stephenson et al. 1991) tundra. In phagotrophic bacterivores usually present and addition, dictyostelids have been reported from often abundant in terrestrial ecosystems. These the layer of soil-like material (“canopy soil”) organisms represent a normal component of the associated with the epiphytes that occur on the microflora in soils and apparently play a role in branches and trunks of tropical trees maintaining the natural balance that exists (Stephenson and Landolt 1998). Dictyostelids between bacteria and other microorganisms in also occur on dung and were once thought to the soil environment (Raper 1984). The be primarily coprophilous (Raper 1984). primary habitat for dictyostelids is the leaf Africa (including the island of Mada- litter decomposition zone of forest soils (e.g., gascar), with a total area of 30.2 million km2, is Swanson et al. 1999). However, they are the second largest continent, occupying more known to occur in other types of soils. Among than 20% of the earth’s land surface. African these are soils of cultivated regions (Agniho- vegetation types are diverse and range from thrudu 1956), grasslands and prairies (Smith & moist tropical forests to grasslands, subtropical, Keeling 1968, Sutherland and Raper 1978), Mediterranean, warm temperate shrubs and
147 woodlands, and deserts. Dictyostelids are an species of Polysphondylium at some point understudied group over most of Africa, but during the period between 1897 and 1900 several recent surveys carried out in the context (Kawakami & Hagiwara 2008a,b). This new of a Planetary Biodiversity Inventory project species was recovered from the dung of an ass funded by the National Science Foundation of collected in Liberia (1). At the time, Olive was the United States have added a considerable working towards a Ph.D. degree at Harvard number of new records from several areas of University under the direction of Roland the continent. The objective of this paper is to Thaxter and William Farlow. In his Ph.D. review all previous records of African dictyo- dissertation, he referred to his isolate as stelids and summarize the results obtained in P. verticillatum, but it was later (Olive 1901) these recent surveys. formally described as P. pallidum. While a faculty member at Wabash Methods College (Indiana), senior author J.C. Cavender Except for the early work by Olive (1901) traveled to East Africa on a grant from the and the more recent work of Kawakami and Research Corporation and collected soil Hagiwara (2008a,b), the samples mentioned in samples for isolation of dictyostelids at 13 sites this paper were collected from the soil/humus in Kenya, Uganda and Tanzania (Cavender zone at the surface of the ground, stored in 1969). These sites were Tsavo (2), a thorn- sterile plastic bags or other containers and scrub woodland in Kenya; Mombasa (3), transported to a laboratory for processing. In coastal deciduous forest in Kenya; Moshi (4) some instances, this involved mailing sample and Lake Manyara (5), both ground water material back to the United States. In the forests in Tanzania; the Ituri forest (6) in the laboratory, samples were processed following Congo Basin (near the Uganda-Congo border), procedures similar to those described by the Budongo Forest Reserve (7) and Lake Cavender and Raper (1965). In brief, this Victoria (8), all of which are evergreen or involves dispersing the sample material in semi-evergreen rain forests in Uganda; Fort sterile distilled water, then placing small Portal (9) in Uganda, the Ngorogoro Crater (10) measured aliquots of the resulting suspension in Tanzania, the Aberdare Mountains (11) in in Petri dishes containing hay infusion agar Kenya, the Kilimanjaro Volcano (12) in (Raper 1984), and finally adding a suspension Tanzania, and the Muhavura Volcano (13) in of Escherichia coli to each dish. Soil Uganda, all of which are montane tropical suspensions prepared in this manner contain forests except at the very highest elevations, viable dictyostelid propagules in the form of where temperate forests occur; and near the spores, active amoebae or encysted, resting summit of Mt. Muhavura in Uganda, an alpine amoebae called microcysts, and all of these Senecio-Lobelia community located at an have the potential of yielding clones that are elevation of ca 4267 m [14000 ft]. No capable of undergoing cell aggregation and dictyostelids were recovered from the samples fruiting on the agar surface (Raper 1984). collected near the summit of Mt. Muhavura, Particular isolates derived from spores obtained but 10 species were recorded from the other from newly formed fruiting bodies then can be collecting sites as well as lower on the subcultured to facilitate identification and/or be mountain. These were Dictyostelium mucoroi- conserved for future study. des, D. giganteum, D. minutum, D. purpureum, The locations of sites from which D. polycephalum, D. lavandulum, D. tenue, samples for isolation of dictyostelids were Polysphondylium pallidum, P. violaceum and collected are indicated in Fig. 1. The numbers Acytostelium leptosomum. Eight of these provided in the figure refer to particular occurred in the rain forest collecting sites, collecting sites listed and briefly described in although one species (D. minutum) was found the section that follows. only in montane temperate forests (Cavender 1969). Results and Discussion Hagiwara (1976), who collected samples The first report of a dictyostelid from from several sites in the Mount Margherita area Africa was by Edgar Olive, who isolated a new (14) of East Africa during the summer of 1974,
148 Mycosphere
Fig. 1. – Locations of sites in continental Africa and Madagascar from which samples for isolation of dictyostelids have been collected. Numbers refer to particular collecting sites (1–43) referred to in the text. recovered 11 species of dictyostelids. This total macrocephalum, P. violaceum, P. pallidum, P. included five described species (Dictyostelium tenuissimum and P. pseudocandidum. After minutum, D. monochasioides, D. mucoroides, slash and burn, only four species were D. purpureum and Polysphondylium viola- recovered. The number of dictyostelids (11 ceum) along with six forms that could not be species) was greatest for a plot in which slash assigned to any described species. and burn had occurred 14 years earlier. At the After moving to Ohio University, time the samples were collected, the plot had a Cavender and R. Bradshaw, a Ph.D. student forest of small trees covering the soil. After 34 who served as an interpreter, traveled to the years, the number of species of dictyostelids Central African Republic on an International had dropped to seven. At the forest edge there Programs grant from NSF and collaborated were nine species, and eight occurred within with Jacques-Paulin Regner and Thomas the mature forest (Cavender et al. 1993). These Damio (both at the University of Bangui). data suggested that disturbance may have Their objective was to study the effects of slash actually stimulated dictyostelid diversity when and burn agriculture on the assemblages of the natural vegetation was allowed to recover. dictyostelids in forest soils. A study area was A total of 57 isolates, identified and uniden- selected in an evergreen rain forest near the tified, from this study and the previous study village of Bagandu (15), which is adjacent to were preserved by lyophilization and are one of the Biosphere Reserves in the Central deposited in the Kenneth B. Raper Dictyostelid African Republic. Thirteen species were Collection housed at Ohio University. recorded in the study area. These were S.L. Stephenson traveled to Kenya and Dictyostelium mucoroides, D. giganteum, D. Tanzania in the summer of 1990. While in polycephalum, D. purpureum, D. aureostipes, Kenya, he collected a small series of samples D. tenue, D. lavandulum, D. firmibasis, D. from the alpine zone (>3962 m [13,000 ft]) on
149 Mt. Kenya (16). However, none of these seven sites in Kruger National Park (18). These samples yielded dictyostelids. As such, his samples were processed by Cavender and results conformed to what Cavender had Landolt. Six already described species of dic- reported earlier for Mt. Muhavura in Uganda. tyostelids were isolated, along with an un- In 1995 Kawakami and Hagiwara (2008a, known species of Acytostelium, two unknown b) traveled to Sierra Leone near Freetown (17) species of Polysphondylium and two unknown in an effort to collect mating types of Poly- species of Dictyostelium (one of which, Krug sphondylium pallidum that might possibly 6-5A, resembles D. aureostipes). The described represent Olive’s isolate. They were unable to species were D. giganteum, D. purpureum, reach Liberia because of the country’s internal D. sphaerocephalum, D. lavandulum, D. poly- conflict but did obtain mating types of P. palli- cephalum and P. violaceum. There also were dum as well as those belonging to a new numerous isolates of a light-spored species of species that was later described as P. multicys- Polysphondylium (Krug 6-5B, Krug 6C) that togenum because of its numerous microcysts. resembles P. asymmetricum, and this unknown In 2005, Peter Njuguna, a graduate species is currently being sequenced by student at the University of Arkansas, collected Romeralo. This is also the case for two of the a few samples at several sites in the Aberdare unknown species (Krug 15A and Krug 6-5A) Mountains (11) of Kenya. These were pro- of Dictyostelium. cessed by J.C. Landolt at Shepherd University. In November of 2006, Cavender, During the summer of the following year, G.G. working with Roux and Karin Jacobs Ndiritu collected soil samples from a number of (University of Stellenbosch) collected samples additional sites located at various elevations for dictyostelids throughout the forested areas throughout the same mountains. These soil of the Republic of South Africa. Collecting samples were processed for dictyostelids by sites were six different regions on Table Cavender at Ohio University, by Landolt at Mountain (19), Jonkershock and Stellenbosch Shepherd University and by Stephenson at the (20), Knysna Big Tree (21), Tsitsikamma and University of Arkansas. Ten species were iden- Storm River (22), Monkeyland (23) and the tified from samples collected in the Aberdare Birds of Eden Sanctuary (24), Western Cape, Mountains. These were Dictyostelium gigan- in the more temperate region of the country; teum, D. leptosomum, D. mucoroides, D. minu- the Amatikulu Nature Reserve (25), Ongoye tum, D. sphaerocephalum, D. aureum, D. (26), Twin Streams (27), Raphia National polycephalum, Polysphondylium violaceum, Monument (28), and the Hluhluwe-Umfolozi P. tenuissimum and Acytostelium sp. In Game Reserve (29) in subtropical vegetation in addition, there were a number of other isolates Zululand; and Makhado (30) and Barotta (31) that could not be assigned to any known in Limpopo, an area of montane forests. Very species. Isolates of these were deposited at the few clones of dictyostelids were recorded from American Type Culture Collection (ATCC) the temperate region. Only six species and are currently being sequenced by Maria (Dictyostelium mucoroides, D. giganteum, Romeralo at Uppsala University in Sweden. D. leptosomum, D. implicatum, P. violaceum The most significant of these as yet uniden- and P. pallidum) were widely distributed, tified isolates are Kenya 17B (a species that while D. minutum and two unknown species in resembles D. polycarpum), Kenya 28 (a very the same genus (Eden 1 and Eden 2) were small Dictyostelium with oval, consolidated recovered from samples collected at the Birds PG+ spores), Kenya 17A (a small and delicate of Eden Sanctuary. Subtropical soils were species of Polysphondylium), Kenya 19A (a richer in dictyostelids and yielded a number of small clustered Dictyostelium with PG- spores), additional species. These were D. polycepha- Kenya MK-1A (a form that may be interme- lum, D. purpureum, D. lavandulum, P. cf. diate between Dictyostelium and Polysphondy- asymmetricum and Acytostelium sp. as well as lium), and Kenya MK-10A (a species of a crampon-based species from Ongoye that Polysphondylium with oval spores). resembles D. vinaceo-fuscum and an unknown In August of 2006, Jolanda Roux species of Polysphondylium from Raphia (University of Pretoria) collected samples from National Monument. Isolates of these four
150 Mycosphere dictyostelids (Eden 1, Eden 2, Ong 2 and MZ 6) Collectively, all of the efforts outlined are currently being sequenced by Romeralo. above provide a reasonable body of data on the Earlier in 2006, through the efforts of dictyostelid biota of only portions of the entire Marianne Meyer and Khalid Yamni, a set of continent of Africa, with the Aberdare samples for possible isolation of dictyostelids Mountains of Kenya probably representing the was obtained in Morocco (32) during a best known region. Most of what is now known collecting trip to that country. These samples, about the dictyostelids of continental Africa which were sent to Cavender for processing, has been derived from collecting sites in East yielded only Dictyostelium mucoroides and Africa and South Africa. Only limited data D. sphaerocephalum. exist for West Africa and Central Africa, and In May of 2009, samples for dictyostelids we are aware of records of only two species of were collected by Carlos Lado (Real Jardin dictyostelids from all of North Africa. Botanico in Madrid, Spain) from 13 sites on Clearly, considerable additional work the island of Madagascar as one component of remains to be done. This is certainly the case a comprehensive survey of the eumycetozoans for the vast area of tropical rain forest that of the island. Collecting sites were in exists in the Congo Basin, which seems likely Ranomafana National Park (33) and Mandraka to support a particularly diverse assemblage of (34), both humid tropical forest; L’Isalo dictyostelids. Except for a few collecting sites National Park (35), tropical forest and sclero- on the north and east margins, this region of phyllous forest; Andringitra National Park (36), Africa remains virtually untouched. secondary tropical forest and grassland; Berenty National Reserve (37), Euphorbia and Summary Alluaudia dry forest; Ihosy (38), dry forest; Although Africa remains an understudied Ambovombe (39), Euphorbia dry forest; continent for dictyostelids, at least 25 species Andohaela National Park (40), leguminose dry have been documented to occur in continental forest; Ambositra (41), sclerophyllous forest; Africa and about the same total is now known Betroka-Beraketa (42), xerophyllous scrub and for the island of Madagascar. These totals savannah; and Ihosy-Betroka (43), Eucalyptus include an appreciable number of forms that forest and grassland. The samples were pro- are new to science but have yet to be formally cessed for dictyostelids by Cavender and described. Landolt. Madagascar proved to have unusually rich environments for dictyostelids. Thirteen Acknowledgements described species (Dictyostelium mucoroides, The research reported herein was funded D. giganteum, D. sphaerocephalum, D. lep- largely by a grant (#DEB-0316284) from the tosomum, D. purpureum, D. lavandulum, National Science Foundation to the University D. vinaceo-fuscum, D. tenue, D. polycephalum, of Arkansas. Thanks are extended to Carlos D. minutum, D. deminutivum, D. implicatum Rojas, who prepared the image used for Figure and Polysphondylium violaceum) were 1. identified. In addition, isolates of five different light-spored species of Polysphondylium (P. References sp.1-MAD 29, P. sp. 2-MAD 44, P. sp. 3- MAD 14D, P. sp. 4-MAD 46, and P. sp. 5- Agnihothrudu V. 1956 – Occurrence of MAD 25) were sent to Romeralo to be Dictyosteliaceae in the rhizosphere of sequenced. Eight isolates of Dictyostelium also plants in southern India. Experientia 12, appear to be new to science. These are MAD 149–151. 5A and MAD 14C (both with yellow Benson MR, Mahoney DP. 1977 – The pigmentation), MAD 52 (characterized by a distribution of dictyostelid cellular slime very slimy sorus and spores), M26B (with very molds in southern California with irregular development), M23A (a species taxonomic notes on selected species. similar to D. implicatum), M10A, M11A and American Journal of Botany 64, 496–503. M12A (all of which are small PG+ species). Cavender JC. 1969 – The occurrence and distribution of Acrasieae in forest soils. II.
151 East Africa. American Journal of Botany Kawakami S, Hagiwara H. 2008b – A 56, 993–998. taxonomic revision of two dictyostelid Cavender JC. 1978 – Cellular slime molds in species, Polysphondylium pallidum and P. tundra and forest soils of Alaska album. Mycologia 100, 111–121. including a new species, Dictyostelium Olive EW. 1901 – A preliminary enumeration septentrionalis. Canadian Journal of of the Sorophoreae. Proceedings of the Botany 56, 1326–1332. American Academy of Arts and Sciences Cavender JC. 1983 – Cellular slime molds of 37, 333–344. the Rocky Mountains. Mycologia 75, Raper KB. 1984 – The Dictyostelids. Princeton 897–903. University Press, Princeton, New Jersey. Cavender JC, Bradshaw RA, Regner J-P, Smith KL, Keeling RP. 1968 – Distribution of Damio T. 1993 – Response of soil the Acrasiae in Kansas grasslands. dictyostelid slime molds to agricultural Mycologia 60, 711–712. disturbance in a tropical environment. Stephenson SL, Landolt JC. 1998 – Biotropica 25, 245–248. Dictyostelid cellular slime molds in Cavender JC, Raper KB. 1965 – The Acrasieae canopy soils of tropical forests. in nature. I. Isolation. American Journal Biotropica 30, 657–661. of Botany 52, 294–296. Stephenson SL, Landolt JC, Laursen GA. 1991 Hagiwara H. 1976 – Cellular slime molds from – Cellular slime molds in soils of Mount Margherita (Mts. Ruwenzor1), Alaskan tundra. Arctic and Alpine East Africa. Bulletin of the National Research 23, 104–107. Science Museum, Series B (Botany) 2, Sutherland JB, Raper KD. 1978 – Distribution 53–62. of cellular slime molds in Wisconsin Kawakami S, Hagiwara H. 2008a – prairie soils. Mycologia 70, 1173–1180. Polysphondylium multicystogenum sp. Swanson AR, Vadell EM, Cavender JC. 1999 – nov., a new dictyostelid species from Global distribution of forest soil Sierra Leone, West Africa. Mycologia dictyostelids. Journal of Biogeography 26, 100, 347–351. 133–148.
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