Black Widow Spider Latrodectus cinctus (Araneae ...

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Black Widow Spider Latrodectus cinctus (Araneae: Theridiidae) New to Liberia—Savanna Species in the Forest Zone FRANK-THORSTEN KRELL AND MARION WILD 1 Eberhard-Karls-Universitat, Zoologisches Institut, Lehrstuhl fiir Spezielle Zoologie, Auf der Morgenstelle 28, D—72076 Tubingen, Germany

J. Med. Entomol. 31(6): 927-930 (1994)

ABSTRACT The first record of the African black widow spider, Latrodectus cinctus Blackwall, 1865 (=L. indistinctus Pickard-Cambridge, 1904) from Liberia is presented. It is a further record of a savanna species in the forest zone of West Africa. Increasing deforestation may cause expansion of the ranges of savanna-inhabiting animal species into the forest zone. KEY WORDS Latrodectus, Liberia, deforestation

SPIDERS of the genus Latrodectus Walckenaer are among the most notorious spiders because of their human pathogenic importance and their worldwide distribution. Variable black widow spiders were subsumed under the name Latrodectus mactans (F.) by Levi (1959) who treated some of the different geographic forms as subspecies, e.g., L. mactans cinctus Blackwall from southern Africa. Since then, several authors including Levi himself, realized the biological distinctness of these forms. After crossing experiments, Martindale & Newlands (1982) concluded that the African black widow spiders form a distinct species, which they named L. indistinctus Pickard-Cambridge, 1904. Although they suspected that L. cinctus Blackwall, 1865, might be a senior synonym, the name L. indistinctus has become established in southern Africa. Recently, Schmidt (1990, 1993a-c), Schmidt et al. (1994), and Griffin & Dippenaar-Schoeman (1992: 160) used the older name. We did not see the typical material, but because Blackwall's (1865: 34If) description corresponds to the habitus of L. indistinctus as shown by Smithers (1944), we likewise decided to use Latrodectus cinctus as its senior synonym and valid name. Moreover, there also exist two additional older names for the African black widow spider (Levi 1959: 27): Latrodectus stuhlmanni Dahl, 1902, and Latrodectus renivulvatus Dahl, 1902. Hence, according to present taxonomic knowledge, L. indistinctus is a junior synonym of three older names and should be avoided in any case.

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Chorology The presumed range of L. cinctus extends from eastern to southern Africa (Levi 1959: 13). Until now, only two reliable records of L. cinctus from western Africa have been published: Assomada and Tarrafal on Santiago in Cape Verde (Schmidt et al. 1994). The record of L. mactans from Dakar in Senegal given by Levi (1959: 36) might refer to L. cinctus or Latrodectus lugubris Dufour, because he subsumed both species under the name L. mactans. Dahl's (1902: 45) record of L. cinctus from Togo has never been revised2. In an unpublished report, we announced having found one Latrodectus specimen in Liberia (Krell & Wild 1989), which we have now identified as L. cinctus (Fig. 1): Liberia, Bong County, near Bong Town, in a grass field (Fig. 2) some 20-30 m from the building of the Liberia Research Unit of the Tropical Institute Hamburg, in its web on the ground, preying on a scarab beetle (Scarabaeidae: Gymnopleurus sp.), in the evening, 22-111-1988, leg. Krell, in coll. Krell. It is an immature female, hence, lacking diagnostic characters in the genitalia, but its coloration (Fig. 1) corresponds to spiderlings of L. cinctus as shown by Smithers (1944: 295), and it is in accordance with the original description of Blackwall (1865: 341f). Its web structure resembled Lamoral's (1968: 5) drawing of the nest of L. cinctus from South Africa. 2 Since this article was written, we received Lotz (1994). Although the author executed some taxonomic splittings at the species level, our determination is still correct. He lists four examined records from West Africa (Morocco, Ghana, German Togo) but no record from the forest zone.

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Fig. 1. Opisthosoma of the spiderling of L. cinctus Blackw. from Liberia, (a) from dorsal (four bright red transversal and one apical median stripe on blackish ground), (b) from ventral (reddish hourglass on blackish ground). Length: 4.0 mm.

This specimen is the first record of Latrodectus from Liberia as well as the first record of L. cinctus in the forest zone of West Africa. Ecology: Savanna Species in the Forest Zone in Liberia The Afrotropical species of Latrodectus are inhabitants of tropical savanna and bushland as well as of the Cape fynbos and karoo zones (Levi

Fig. 2. Collecting locality of L. cinctus on the Bong Mining Company's concession area. The web was situated on the ground in the grassland in the middle of the photograph.

1959). The collecting locality in Liberia is situated in the mosaic of wetter and drier types of Guinea-Congolian lowland rainforest (White 1983). Nearly the whole territory of Liberia is situated in the Guinea-Congolian lowland rainforest zone, which is an unsuitable habitat for Latrodectus. Only the coastal strip is covered by a mosaic of lowland rain forest and secondary grassland (White 1983), which is man made by shifting the cultivation for = 150 yr (Kunkel 1964: 325). Increased deforestation results in fragmentation of the forests and spreading of savannalike habitats. Thus in their recent mapping of land cover Millington et al. (1992: 48f) found no forest, but only high woody biomass mosaics (=transitional zones between forest and savanna woodland) in Africa in the west of Nigeria. Recently, Garms et al. (1991) observed that some savanna species of black flies (Diptera: Simulium spp.) penetrated deeply into the forest zone during dry seasons. Their populations increased enormously in the man-made savanna-like areas within the Bong Mining Company's concession area where the aforesaid L. cinctus specimen was found. Transport of men and goods between the Bong Mine and the coastal area had been frequent. Records of L. mactans in Great Britain and Ireland (Ross 1988) indicate that Latrodectus species are able to stay alive during transport over long distances and to survive in foreign environments. Hence, man-made introduction of widow

November 1994

KRELL & WILD: L. cinctus NEW TO LIBERIA

spiders from coastal regions to the Bong Mine is possible. Man-made grasslands enable Latrodectus to establish itself there. The creation of savanna-like areas within the forest zone may cause a rapid expansion of the ranges of savanna inhabiting animal species into the forest zone (cf., Garms et al. 1991: 187, Walsh et al. 1993).

Medical Consequences The venom of female L. cinctus is highly toxic to humans and other vertebrates (Muller et al. 1992). The clinical features of the toxic effects caused by a neurotoxin were compiled by Newlands & Atkinson (1988: 237) and Muller (1993). In most cases, these include muscle pain and cramps, especially in abdomen, chest, and legs, and are often combined with abdominal rigidity, difficulty in breathing, or pyrexia etc. Bites of L. cinctus have not been proven fatal for healthy adults. During the Liberian civil war, however, the poor health of the population may increase the medical importance of Latrodectus. In Liberia and the surrounding countries where Latrodectus has been hitherto unknown, the medical practitioners should make themselves familiar with the symptoms and treatment of latrodectism. Acute abdomen, myocardial infarction, alcohol withdrawal, organophosphate poisoning, cytotoxic spider bites, scorpion sting, and snakebite should be considered in the differential diagnosis (Muller 1993). A specific antivenom is available from the South African Institute for Medical Research (Newlands & Atkinson 1988).

Acknowledgments We extend our sincere thanks to R. Sachs (formerly of the Liberia Research Unit (LRU) of the Tropical Institute Hamburg), who gave permission to use the LRU institute as research base for our work in the Bong area. We are indebted to G. Schmidt (Deutsch Evern), F. Piepho (Iserlohn), and L. N. Lotz (National Museum Bloemfontein) for their helpful comments and for confirming our determination. R. Garms (Bernhard-NochtInstitut fur Tropenmedizin, Hamburg) informed us about some relevant parasitological references.

References Cited Blackwall, J. 1865. Descriptions of recently discovered species, and characters of a new genus, of Araneidea from the east of central Africa. Ann. Mag. Nat. Hist. 16: 336-352. Dahl, F. 1902. Uber abgebrochene Copulationsorgane mannlicher Spinnen im Korper der Weibchen. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1902: 36-45.

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Garms, R., R. A. Cheke & R. Sachs 1991. A temporary focus of savanna species of the Simulium damnosum complex in the forest zone of Liberia. Trop. Med. Parasitol. 42: 181-187. Griffin, E. & A. S. Dippenaar-Schoeman 1992. A checklist of, and references to, the Namibian spider fauna (Arachnida, Araneae). Cimbebasia 13: 155181. Krell, F.-T. & M. Wild 1989. Beetles and spiders of medical importance in Liberia. Liberia Research Unit of the Tropical Institute Hamburg. Annual Report 1988: 74-76. Kunkel, G. 1964. Die kiinstliche Kustensavanne Liberias. Geogr. Z. 52: 324-328 (plates 1 and 2). Lamoral, B. H. 1968. On the nest structure of Latrodectus in South Africa, and some observations on body colouration of L. geometricus (Araneae: Theridiidae). Ann. Natal Mus. 20: 1-14. Levi, H. 1959. The spider genus Latrodectus (Araneae, Theridiidae). Trans. Am. Microsc. Soc. 78: 7-43. Lotz, L.N. 1994. Revision of the genus Latrodectus (Araneae: Theridiidae) in Africa. Navors. Nas. Mus., Bloemfontein 10: 1-60. Martindale, C. B. & G. Newlands 1982. The widow spiders: a complex of species. South Afr. J. Sci. 78: 78-79. Millington, A. C., P. J. Styles & R. W. Critchley 1992. Mapping forests and savannas in sub-Saharan Africa from advanced very high resolution radiometer (AVHRR) imagery, pp. 37-62. In P. A. Furley, J. Proctor & J. A. Ratter [eds.], Nature and dynamics of forest-savanna boundaries. Chapman & Hall, London. Muller, G. J. 1993. Black and brown widow spider bites in South Africa. A series of 45 cases. South Afr. Med. J. 83: 399-405. Muller, G. J., A. B. Kriegler, J. M. Van Zyl, B. J. Van der Walt, A. S. Dippenaar & P. P. Van Jaarsveld 1992. Comparison of the toxicity, neurotransmitter releasing potency and polypeptide composition of the venoms from Steatoda foravae, Latrodectus indistinctus and L. geometricus (Araneae: Theridiidae). South Afr. J. Sci. 88: 113-116. Newlands, G. & P. Atkinson 1988. Review of southern African spiders of medical importance, with notes on the signs and symptoms of envenomation. South Afr. Med. J. 73: 235-239. Pickard-Cambridge, O. 1904. Descriptions of some new species, and characters of three new genera, of Araneidea from South Africa. Ann. South Afr. Mus. 3: 143-165 (plates IX-XII). Ross, H.C.G. 1988. A record of the black widow spider (Latrodectus mactans (Fabricius) (Araneae: Theridiidae)) in Ireland. Ir. Nat. J. 22: 537. Schmidt, G. 1990. Courtship behaviour, copulation and crossing experiments in Latrodectus species (Araneida: Theridiidae). Acta. Zool. Fenn. 190: 351-355. 1993a. Schwarze, Wei/3e und Rote Witwen. Aquarium (Minden) 290: 35-39. 1993b. Giftige und gefahrliche Spinnentiere. Humanpathogene Skorpione (Scorpionida), Milben (Acarina) und Spinnen (Araneida) (Neue BrehmBiicherei 608). Westarp Wissenschaften, Magdeburg.

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1993c. Further crossing experiments in Latrodectus species (Araneida: Theridiidae). Bull. Soc. Neuchatel. Sci. Nat. 116: 215-222. Schmidt, C , M. Geisthardt & F. Piepho 1994. Zur Kenntnis der Spinnenfauna der Kapverdischen Inseln (Arachnida: Araneida). Mitt. int. entomol. Ver. (Frankf. a. M.) 19: 81-126. Smithers, R.N.N. 1944. Contributions to our knowledge of the genus Latrodectus (Araneae) in South Africa. Ann. South Afr. Mus. 36: 263-313 (1 plate, 2 maps). Walsh, J. F., D. H. Molyneux & M. H. Birley 1993. Deforestation: effects on vector-borne disease,

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pp. S55-S75. In: W. Hominick [ed.]. The impact of global change on disease. Symposium of the British Society of Parasitology 30 (Parasitology 106). White, F. 1983. Unesco/AETFAT/UNSO vegetation map of Africa. Scale 1:5,000,000. 3 maps; 1 legend. / The vegetation of Africa. A descriptive memoir to accompany die Unesco/AETFAT/UNSO vegetation map of Africa. Unesco, Paris.

Received for publication 1 April 1994; accepted 12 July 1994.