Hydrobiologia 446/447: 247–254, 2001.L. Sanoamuang, H. Segers, R.J. Shiel & R.D. Gulati (eds), Rotifera IX.© 2001 Kluwer Academic Publishers. Printed in the Netherlands.

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Rotifera from Burundi: the Lepadellidae (Rotifera: Monogononta)

Deo Baribwegure1,2 & Hendrik Segers1

1Laboratory of Animal Ecology, Zoogeography and Nature Conservation, Department Biology,University of Ghent, K.L. Ledeganckstraat 35, B-9000 Gent, BelgiumE-mail: deo.baribwegure@rug.ac.be Hendrik.Segers@rug.ac.be2Departement de Biologie, Faculte des Sciences, Universite du Burundi, B.P. 2700 Bujumbura, Burundi

Key words: Rotifera, Lepadellidae, Burundi

Abstract

We studied the distribution of Lepadellidae (Rotifera) in freshwater habitats in the floodplain of the River Rusizi innorthwest Burundi. Twenty-three species belonging to Colurella Bory de St. Vincent, 1824 (3 species), LepadellaBory de St. Vincent, 1826 (18 species) and Squatinella Bory de St. Vincent, 1826 (2 species) are recorded, 22 ofthem are new to Burundi. One of the taxa encountered probably represents an unnamed species. Lepadella arabicaSegers & Dumont, 1993 is recognised as junior subjective synonym of Lepadella eurysterna Myers, 1942 (syn.nov.). Most of the taxa recorded are cosmopolitan or tropicopolitan, two are restricted to the tropical regions of theOld World and Australia, and one, Squatinella lunata Segers, 1993 is an Ethiopian endemic.

Introduction

To date, there are few publications dealing with theBurundian rotifer fauna (see De Ridder, 1987), al-though some contributions dealing with zooplanktonfrom Lake Tanganyika exist (e.g. Coulter, 1991). Re-garding Rotifera, Gillard (1957) recorded 62 rotifertaxa from the lake (listed by Coulter in De Ridder,1991), but only one of his localities is from the Bur-undian part of the lake. Wulfert (1965), working onone of Gillard’s samples, described two additional taxafrom the surroundings of Lake Tanganyika: Colurellacollaris Wulfert, 1965 (tentatively considered a syn-onym of C. uncinata (Müller, 1773) f. bicuspidata(Ehrenberg, 1832) by Koste, 1978) and Lepadellaminuta (Weber & Montet, 1918) f. africana Wulfert(taxonomic validity rejected by Koste, 1978). Fromthe information on the occurrence of species in thesample it can be inferred that Wulfert (1965) wasstudying a sample from Gillard’s (1957) station 334,a swamp near Albertville (Kalemi), Congo. Recently,Segers & Baribwegure (1996) described an apparentlyendemic Lecane from swamps near Lake Tanganyikain Burundi.

In this contribution, we present results on theLepadellidae found in samples from water bodies in

the floodplain of River Rusizi in North-West Burundi.The family is one of the most important and speci-ose taxa of littoral-benthonic rotifers. To date, onlya single representative, Lepadella (Heterolepadella)ehrenbergi (Perty, 1850), is known from Burundi (Gil-lard, 1957). A record consisting of a single Lepadel-lidae from a region naturally endowed with a widevariety of freshwater habitats is low when comparedto surveys of other African waters. This dearth of re-cords illustrates the need for a more extensive surveyon Burundian rotifers.

Materials and methods

Study samples were collected using a 35 µm-meshplankton net and preserved in 4% formalin. For ana-lysis, specimens were picked under a Wild M3 dis-secting microscope, and drawn under a Medilux-12microscope with drawing tube at 1000× magnific-ation. For species identification, the keys by Koste(1978) and Koste & Shiel (1989) were used.

The floodplain of River Rusizi extends 80 kmalong the stream in west and northwest Burundi. It islocated from the northern bay of Lake Tanganyika upto the confluence of River Rusizi with River Ruhwa at

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the border between Burundi and Rwanda. The studyarea is located between 2◦ 45′–3◦ 30′ S and 29◦ 10′–29◦ 15′ E at an altitude varying between 740 and900 m. The climate is tropical with two rainy seasons(February–May and November–December).

The following localities were sampled (see Map 1):1. Locality 1: Littoral zone of Lake Tanganyika

between ‘Musée Vivant’ and the port of Bujum-bura (one sample, leg. H.J. Dumont, 01 May1983).

2. Localities 2 and 3: Two natural lakes in the delta ofRiver Rusizi near Lake Tanganyika (Park of Rus-izi) (Five and four samples, respectively, 5–11 July1996).

3. Locality 4: Small water bodies and connectingditch between localities 2 and 3, Park of Rusizi(3–9 July 1996).

4. Locality 5: Temporary pond in Rukoko (Reserveof Rusizi), North of Bujumbura airport (Threesamples, leg. A. Caljon, 21 December 1981).

5. Locality 6: Pond near River Kajeke (One sample,leg. A. Caljon, 09 April 1990).

6. Localities 7 and 8: Two rice fields along a roadto Rukaramu project near Bujumbura airport (Twosamples each, 26 March 1996).

7. Locality 9: Abandoned fishpond in Rukaramuproject (One sample, 26 March 1996).

Results and discussion

The samples yielded a total of 23 Lepadellidae (Table1). Three of the four genera of Lepadellidae are rep-resented: Colurella Bory de St. Vincent, 1824 withthree species, Lepadella Bory de St. Vincent, 1826with eighteen species, and Squatinella Bory de St.Vincent, 1826 with two species. Two of the taxafound are taxonomically noteworthy. One, an appar-ent relative of Lepadella acuminata (Ehrenberg, 1834)(Figs 42–43) resembles L. elongata Koste, 1992 andL. neglecta Segers & Dumont, 1995, and has previ-ously been reported as L. cryphaea Harring, 1916 by,amongst others, Segers et al. (1993a). We refrain fromtreating the taxon in full detail here, in view of thescarcity of specimens in the Burundian samples andthe taxonomic confusion in the group.

The Burundian collection contained specimens ofLepadella eurysterna Myers, 1942 (Figs 35–37). Acomparison of the present material with paratypesof L. eurysterna (Academy of Natural Sciences ofPhiladelphia rotifer collection nr. 964, Naomi Lake,

Monroe Co., Pa, U.S.A. coll. 16 August 1939), con-specific specimens from Lenape Lake, Atlantic Co.,NJ, U.S.A. (coll. 6 July 1996), and type specimensand topotypic material of L. arabica Segers & Du-mont, 1993, revealed that L. eurysterna is a seniorsynonym of L. arabica (NEW SYNONYM). The lor-ica outline of the species is rather variable, but it canbe recognised by its relatively flat lorica, as in L. ovalis(Müller), and convex rather than deeply concave pos-terior lorica margin (compare Figs 35–37 with Fig.34). The original description of L. eurysterna by My-ers (1942) is misleading by its brevity, and by theselection of animals depicted. This may explain whyL. eurysterna has not been reported since its descrip-tion. Lepadella arabica was described from northeastSaudi Arabia, and subsequently recorded from Nigeria(Segers et al., 1993a). The species has also been foundin collections from two ponds in New Delhi, India (DrS. Nandini, unpublished). Apparently, L. eurysternais a cosmopolitan, and possibly warm-stenothermicspecies.

A number of species recorded were known fromone or two African localities only. These are as fol-lows:1. Lepadella apsicora Myers, 1934 (Figs 15–16):

The present record is the second of this speciesfrom the African continent, after a record from Ni-geria (Segers et al., 1993a). It is also known fromMadagascar (Berzins, 1982) and the ComorosIslands (Segers, 1992), and is tropicopolitan.

2. Lepadella apsida Harring, 1916 (Fig. 17): Theonly previous African record of this rare but cos-mopolitan species is from Senegal (De Ridder,1983). The animal can easily be confused with L.lindaui Koste, but has a smooth dorsal lorica.

3. Lepadella discoidea Segers, 1993 (Figs 30–31):To date, African records of this species are fromNigeria and Congo (Segers, 1993). The species iswidespread in the tropical regions of the Old Worldand Australia.

4. Lepadella lindaui Koste, 1981 (Figs 27–28): Thepresent record is the third African of this animal,after its description from Kenya (Koste, 1981), anda record from Nigeria (Segers et al., 1993a). Inaddition, the species has been recorded from NorthAustralia (Koste, 1981), and Brazil (Segers et al.,1993b).

5. Lepadella triba Myers, 1934 (Figs 42–43): OurBurundian record is the third African of this cos-mopolitan species, after reports from Senegal (DeRidder, 1983) and Nigeria (Segers et al., 1993a).

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Map 1. (I) Map of Burundi, indicating the sampled region (inset), (II) sampled localities.

Table 1. Colurellidae recorded from Burundi

Colurella adriatica Ehrenberg, 1831 (Figs 1–3): Loc. 3 (c)∗Colurella obtusa (Gosse, 1886) (Figs 4–6): Loc. 2, 4, 5, 8, 9 (c)1∗∗Colurella uncinata (Müller, 1773) f. bicuspidata (Ehrenberg, 1832) (Figs 7–12): Loc. 2 (c)

Lepadella amphitropis Harring, 1916 (Figs 13–14): Loc. 2 (c)

Lepadella apsicora Myers, 1934 (Figs 15–16): Loc. 2, 4, 5 (t)

Lepadella apsida Harring, 1916 (Fig. 17): Loc. 2 (t)

Lepadella biloba Hauer, 1958 (Figs 18–19): Loc. 3, 4, 9 (c)

Lepadella costatoides Segers, 1992 (Figs 24–25): Loc. 2, 3, 4, 5, 7 (t)

Lepadella discoidea Segers, 1993 (Figs 30–31): Loc. 2, 3, 4, 5, 6, 7, 8, 9 (pal)∗Lepadella ehrenbergi (Perty, 1850) (Figs 32–33): Loc. 3, 4 (c)

Lepadella eurysterna Myers, 1942 (Figs 35–37): Loc. 3, 4 (t)∗Lepadella heterostyla (Murray, 1913) (Figs 38–39): Loc. 1, 4 (c)

Lepadella latusinus (Hilgendorf, 1899) (Figs 20–21): Loc. 1, 4, 8 (c)

Lepadella lindaui Koste, 1981 (Figs 26–27): Loc. 4 (pan)∗Lepadella ovalis (Müller, 1786) (Fig. 34): Loc. 4, 5 (c)∗Lepadella patella (Müller, 1786) (Figs 22–23): Loc. 2, 4, 7, 8 (c)

Lepadella rhomboides (Gosse, 1886) (Figs 40–41): Loc. 1, 5 (c)

Lepadella sp. near acuminata (Figs 44–45): Loc. 2, 4

Lepadella triba Myers, 1934 (Figs 42–43): Loc. 5 (c)

Lepadella triptera (Ehrenberg, 1830) (Figs 28–29): Loc. 3, 4, 8 (c)∗Lepadella vandenbrandei Gillard, 1952 (Figs 46–48): Loc. 6 (pal)

Squatinella lunata Segers, 1993 (Fig. 49): Loc. 4 (e)

Squatinella lamellaris (Müller) f. mutica (Ehrenberg, 1832) (Figs 50–51): Loc. 2 (c)

(c): cosmopolitan; (e): endemic; (pal): tropical regions of the Old World and Australia; (pan):pantropical; (t): tropicopolitan.∗, ∗∗: species recorded by Gillard (1957) and Wulfert (1957), respectively, from Lake Tanganyika.Additional records from the lake are by Gillard (1957: L. acuminata, L. cristata, and Paracolurellaaemula), and Wulfert (1957: L. minuta f. africana).1As C. collaris Wulfert, 1965.

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Figures 1–12. Colurella spp. 1–3: C. adriatica, 4–6: C. obtusa, 7–12: C. uncinata f. bicuspidata. 1, 4, 7, 8: ventral, 2, 5, 9, 10: dorsal, 3, 6, 11,12: lateral.

6. Squatinella lunata Segers, 1993 (Fig. 49): Thisapparent African endemic was described from Ni-geria (Segers, 1993), and is now also known fromBurundi.

All taxa but L. ehrenbergi are new to the Burundianfauna, all had been recorded from Africa before. Themajority of animals recorded are cosmopolitan (14taxa, 61%), or widely distributed species with ther-mophilic character (tropicopolitans: 4 taxa, 17%) (seeTable 1). One species is Pantropical (4%). Taxa ofparticular zoogeographic relevance are the Paleotrop-ical L. discoidea and L. vandenbrandei Gillard, 1952

(Figs 46–48), and the Ethiopian endemic S. lunata.The diversity of Lepadellidae in the sampled loc-alities appears relatively high, considering that DeRidder (1986, 1991, 1994) mentions a total of only49 Lepadellidae from African freshwaters. A recordof 23 Lepadellidae is high relative to the results by DeSmet (1989, 1991), who lists eight and 13 Lepadel-lidae from water bodies on Mount Kilimanjaro, Tan-zania, and from localities in the Bas-Zaïre, Republicof Congo, respectively. On the other hand, De Rid-der (1981) records 22 Lepadellidae from East Congo,and Segers et al. (1993a) lists 33 species from varioushabitats in the lower delta of River Niger. It appears

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Figures 13–29. Lepadella spp. 13–14: L. amphitropis, 15–16: L. apsicora, 17: L. apsida, 18–19: L. biloba, 20–21: L. latusinus, 22–23: L.patella, 24–25: L. costatoides, 26–27: L. lindaui, 28–29: L. triptera. 13, 15, 17, 18, 20, 22, 24, 26, 28: ventral, 14, 16, 19, 21, 23, 25, 27, 29:dorsal.

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Figures 30–41. Lepadella spp. 30–31: L. discoidea, 32–33: L. ehrenbergi, 34: L. ovalis, 35–37: L. eurysterna, 38–39: L. heterostyla, 40–41: L.rhomboides. 30, 32, 34, 36–38, 40: ventral, 31, 33, 35, 39, 41: dorsal.

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Figures 42–51. Lepadella spp. 42–43: L. triba, 44–45: L. sp. near acuminata, 46–48: L. vandenbrandei. Squatinella spp. 49: S. lunata, 50–51:S. lamellaris f. mutica. 42, 44, 46, 49, 50: ventral, 43, 45, 47, 51: dorsal, 48: lateral.

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premature to draw any conclusions from these num-bers, as differences in sampling intensity precludecomparisons. Considering the extent of the sampledarea and sampling effort, the record illustrates a di-verse rotifer taxocoenosis in Burundian freshwaters.Obviously, the present list is non-exhaustive, as mostBurundian inland waters remain unstudied.

Acknowledgements

The first author acknowledges a grant by the Bel-gian Administration for Development and Cooper-ation (B.A.D.C) to work on a Ph.D. dissertation.Samples from the littoral area of the Lake Tanganyika,from Kajeke and Rukoko were collected by Prof. H.J.Dumont and the late Dr A. Caljon. Sampling in Rus-izi Natural Park was aided by logistic support fromCRRHA (Centre Régional de Recherche en Hydrobi-ologie Appliquée). The second author acknowledgessupport from the organizers of the VIIIth Internationalrotifer symposium, to attend the IXth Internationalrotifer symposium.

References

Berzins, B., 1982. Zur Kenntniss der Rotatorienfauna von Madagas-car. Lund, AV centralen I Lund: 24 pp.

Coulter, G. W., 1991. Lake Tanganyika and its life. Natural HistoryMuseum publications. Oxford Univ. Press, Lond./Oxford, N.Y.:354 pp.

De Ridder, M., 1981. Rotifera. In Symoens, J.-J. (ed.), Hydrobiolo-gical Survey of the Lake Bangweulu Luapula River Basin. CercleHydrobiologique de Bruxelles, Bruxelles: 191 pp.

De Ridder, M., 1983. Recherches écologiques et hydrobiologiquessur les Rotifères de la Basse-Casamance (Sénégal). Rev. Hydri-obiol. trop. 16: 41–55.

De Ridder, M., 1986. Annotated checklist of non-marine Rotiferafrom African inland waters. Zool. Doc., kmMA, Tervuren 21:123 pp.

De Ridder, M., 1987. Distribution of rotifers in African fresh andinland saline waters. Hydrobiologia 147: 9–14.

De Ridder, M., 1991. Additions to the “Annotated checklist of non-marine rotifers from African inland waters”. Rev. Hydrobiol.trop. 24(1): 25–46.

De Ridder, M., 1994. Additions II to the “Annotated checklistof non-marine rotifers from African inland waters”. Biol. Jb.Dodonaea 61: 99–153.

De Smet, W. H., 1989. Contributions to the rotifer fauna of the Bas-Zaïre. 1. The rotifers from some small ponds and a river. Biol.Jb. Dodonaea 56: 115–131.

De Smet, W. H., 1991. Rotifers from the Kilimanjaro. Biol. Jb.Dodonaea 58: 120–130.

Gillard, A., 1957. Exploration hydrobiologique du Lac Tanganyika(1946–1947). Inst. Roy. des Sc. Nat. de Belgique. Vol. III (fasc.6). 3–26 pp.

Koste, W., 1978. Rotatoria. Die Rädertiere Mitteleuropas. Gebr.Borntraeger, Berlin, Stuttgart: 673 pp., 234 plates.

Koste, W., 1981. Zur Morphologie, Systematik und Ökologie vonneuen monogononten Rädertieren (Rotatoria) aus dem Über-schwemmungsbebiet des Magela Creek in der Alligator-River-Region Australiens, N.T. Teil i. Osnabrücker naturwiss. Mitt. 8:97–126.

Koste, W. & R. J. Shiel, 1989. Rotifera from Australia inland watersIV. Colurellidae (Rotifera: Monogononta). Trans. r. Soc. S. Aust.113 (3) 119–143.

Myers, F. J., 1942. The rotatorian fauna of the Pocono plateau andenvirons. Proc. Acad. nat. Sci. Philad. 44: 251–285.

Segers, H., 1992. Taxonomy and zoogeography of the Rotifer faunaof Madagascar and the Comores. J. Afr. Zool. 106: 351–361.

Segers, H., 1993. Rotifera of some lakes in the floodplain of the riverNiger (Imo State, Nigeria). I. New species and other taxonomicconsiderations. Hydrobiologia 250: 39–61.

Segers, H. & D. Baribwegure, 1996. On Lecane tanganyikae newspecies (Rotifera: Monogononta, Lecanidae). Hydrobiologia324: 179–182.

Segers, H., C. S. Nwadiaro & H. J. Dumont, 1993a. Rotifera of somelakes in the floodplain of the river Niger (Imo State: Nigeria). II.Faunal composition and diversity. Hydrobiologia 250: 63–71.

Segers, H., E. N. Dos Santos-Silva & A. L. De Oliveira-Neto,1993b. New and rare species of Lecane and Lepadella (Roti-fera: Lecanidae, Colurellidae) from Brazil. Belg. J. Zool.: 123.113–121.

Wulfert, K., 1965. Rädertiere aus einigen afrikanischen Gewässern.Limnologica (Berlin) 3(3): 347–366.