Anna S. Dippenaar-Schoeman

Micro-scale heterogeneity of spiders (Arachnida: Araneae) in the Soutpansberg, South Africa : a comparative survey and inventory in representative habitats

ABSTRACT Coarse-scale studies that focus on species distributions and richness neglect heterogeneity that may be present at finer scales. Studies of arthropod assemblage structure at fine (1 × 1 km) scales are rare, but important, because these are the spatial levels at which real world applications are viable. Here we investigate fine-scale variation in spider assemblages, comparing five representative vegetation types in the western Soutpansberg, Limpopo Province, South Africa. We assess these vegetation types in terms of their family and species composition, as well as levels of endemicity, relating these differences with vegetation structure. We inventoried 297 species (49 families) in an area less than 450 ha, as part of South African National Survey of Arachnida. Analysis of the results suggests that endemic taxa are associated with Tall Forest and, to a lesser extent, Woodland. The Woodland had the highest species diversity, and much of the variation observed in spider assemblage structure is explained by these two vegetation types. Based on vegetation structure variables that explained significant variation in spider assemblages, human influence through bush encroachment will result in a change of spider assemblages to that of Short Forest and Mosaic Woodland vegetation types, with implications for biodiversity maintenance and heterogeneity.

THE INFLUENCE OF MOUND STRUCTURE ON THE DIVERSITY OF SPIDERS (ARANEAE) INHABITING THE ABANDONED MOUNDS OF THE SNOUTED HARVESTER TERMITE TRINERVITERMES TRINERVOIDES

Abstract The dynamics of spiders present in abandoned Trinervitermes trinervoides (Sjöstedt) termite mounds were studied over a period of one year, from March 1999 to January 2000, with five mounds excavated on a bimonthly basis. All spiders present in the mound were collected by hand and preserved in 70% ethanol. A total of 771 spiders represented by 21 families and 82 species were collected from the 30 mounds during the course of the study. The most abundant were the Gnaphosidae, which represented 37.87% of all spiders collected, followed by the Salticidae (12.97%), Pholcidae (10.51%) and Oonopidae (9.60%). These were the only families that represented more than 5% of the spider fauna. The most abundant species were Zelotes fuligineus (Purcell 1907) (Gnaphosidae) (11.69%), Smeringopus sambesicus Kraus 1957 (Pholcidae) (10.51%), Heliophanus sp. (Salticidae) (9,86%) and a Gamasomorphinae sp. (Oonopidae) (9.21%). A correlation was found between spider abundance and mound height, surface perforation of the mound and season of collection. Spider numbers were highest in mounds with a high surface degradation, while a tendency existed for an increase in numbers with increased mound height. Web-building spiders (Pholcidae and Theridiidae) were largely limited to mounds with a cavity in the structure.

Assessing local scale impacts of Opuntia stricta (Cactaceae) invasion on beetle and spider diversity in Kruger National Park, South Africa

There is a paucity of studies examining direct impacts of introduced alien species on biodiversity, a key need for motivating for alien species control in conservation areas. The introduced prickly pear (Opuntia stricta) has invaded some 35 000 ha of Kruger National Park. We investigated the effect of O. stricta on beetle and spider species assemblages in the Skukuza region of Kruger National Park. We used unbaited pitfall traps over a 12-month period in four treatments of varying O. stricta density. Species richness, species density and abundance of beetles and spiders were compared. A total of 72 beetle and 128 spider species were collected. Species richness and species density for beetles and spiders did not differ significantly across the four treatments. Assemblages for spiders did not differ across treatments but beetle assemblages were significantly different from uninvaded control sites. This study suggests that the current density of O. stricta does not significantly affect spider species richness, density or assemblages but that beetle assemblages are significantly affected.

South African Spider Diversity: African Perspectives on the Conservation of a Mega-Diverse Group

Any field of endeavour requires retrospection after a period of substantial activity. This process provides a measure of what has been achieved and identifies future directions. Studies of spider diversity in South Africa have gone through an intense growth phase over the past ten years and reached a stage in its development where reflections on patterns and processes observed could provide meaningful input into the identification of further work. This chapter establishes the background and framework for such a discussion on the path to a more holistic conservation planning that includes invertebrates. Invertebrate conservation and diversity pose a significant challenge to planners and managers (Engelbrecht, 2010), and in spite of the central role that insects and arachnids play in terrestrial biodiversity, they still remain peripheral to decision-making processes. The reality is that, for Africa in particular, there are very few conservation areas that have both the resources and expertise to include invertebrates as part of their monitoring and management initiatives (however, see South African River Health Programme1). The advent of adaptive management, with a strong emphasis on experimental implementation of alternative management options (Johnson, 1999), has informed much of recent thinking and has cast a dim light on classical inventory studies that generate species lists. However, records of the numbers of species and their distribution provides a fundamental starting point for the conservation of biodiversity (Pullin, 2002). This view also ignores the contribution that basic inventories and alpha taxonomy make to the initial development of a field. This chapter will show that South African spider systematics and ecology are in an exploratory phase, and that traditional approaches to mapping diversity has enabled spider ecology in the country to generate species lists that are often resolved up to species level. Very few other studies on mega-diverse invertebrate groups in Africa can match this taxonomic resolution (see e.g. Formicinae). This descriptive phase will provide the

South African National Survey of Arachnida (SANSA): review of current knowledge, constraints and future needs for documenting spider diversity (Arachnida: Araneae)

Biodiversity is one of the most important concepts in contemporary biology, with a broad range of applications. In November 1995, South Africa ratified the Convention on Biological Diversity (CBD). Signatories are obligated to develop a strategic plan for the conservation and sustainable use of biodiversity. To meet the requirements of the CBD, the South African National Survey of Arachnida (SANSA) was initiated in 1997. This national project has several aims: to document and describe the arachnid fauna of South Africa; to consolidate all the available data on South African arachnids into one relational database and to make this biodiversity information available to science; and to address issues concerning their conservation and sustainable use. Extensive sampling took place and the SANSA database contains a wealth of biodiversity data that are used to provide answers to ecological questions. Presently 71 spider families, 471 genera and 2170 species are known from South Africa, representing approximately 4.8% of the world fauna. This paper presents the current state of spider biodiversity information and how it is managed. It demonstrates the importance of running a national inventory; emphasises the significance of using a good database application; and the importance of capacity development to improve the quality and integration of biodiversity information. Further, it shows the role SANSA has played in unifying and strengthening arachnid research, with the major thrust to discover the spider diversity in South Africa. We discuss the present status of knowledge, constraints to improving this, and the future directions for research. SANSA has provided the foundations for a more integrative approach to spider diversity research. Future research should build on this legacy by linking taxonomic diversity with that of functional diversity, predicting the response of this diversity to global change drivers. Functional approaches will link these studies to ecosystem processes. Global collaborative studies at several sites following standardised sampling protocols and focused research questions would add value to the SANSA collection and the importance of spiders for the health of ecosystems.

Current knowledge of spiders in South African agroecosystems (Arachnida, Araneae)

ABSTRACT Spiders are one of the most abundant predator groups found in agroecosystems and they have special adaptations towards a predatory way of life. The aim of this paper is to review our present knowledge of spider diversity in different agroecosystems of South Africa, as well as their potential prey. This paper provides a measure of what has been achieved in research on spiders in South African agroecosystems, and identifies directions for future research. A checklist of spiders found in these systems is provided, based on published surveys and data from the South African National Survey of Arachnida (SANSA) database, with information on the guilds that they occupy. Thus far, 51 families with 238 genera and 413 species have been recorded from crops in South Africa. Five agrobiont species have been listed that might play an important role as natural control agents of pests: Ostearius melanopygius (O.P.- Cambridge, 1879) (Linyphiidae); Pardosa crassipalpis Purcell, 1903 (Lycosidae); Cheiracanthium furculatum Karsch, 1879 (Miturgidae); Heliophanus pistaciae Wesołowska, 2003 (Salticidae) and Misumenops rubrodecoratus Millot, 1941 (Thomisidae).

The faunistic diversity of spiders (Arachnida: Araneae) of the South African Grassland Biome

ABSTRACT As part of the South African National Survey of Arachnida (SANSA), all available information on spider species distribution in the South African Grassland Biome was compiled. A total of 11 470 records from more than 900 point localities were sampled in the South African Grassland Biome until the end of 2011, representing 58 families, 275 genera and 792 described species. A further five families (Chummidae, Mysmenidae, Orsolobidae, Symphytognathidae and Theridiosomatidae) have been recorded from the biome but are only known from undescribed species. The most frequently recorded families are the Gnaphosidae (2504 records), Salticidae (1500 records) and Thomisidae (1197 records). The last decade has seen an exponential growth in the knowledge of spiders in South Africa, but there are certainly many more species that still have to be discovered and described. The most species-rich families are the Salticidae (112 spp.), followed by the Gnaphosidae (88 spp.), Thomisidae (72 spp.) and Araneidae (52 spp.). A rarity index, taking into account an endemicity index and an abundance index, was determined to give a preliminary indication of the conservation importance of each species. The endemicity index indicates that 58 species are endemic to the biome, while 38 species could be considered to be introduced, cosmopolitan, or having a distribution extending beyond the Afrotropical Region. Levels of endemism are highest for mygalomorph trapdoor spiders (7.14–50%) and selected araneomorph families with restricted dispersal capabilities (i.e. Archaeidae, Sicariidae and Scytodidae). A brief review of the published data of surveys from the biome and the patterns of spider assemblage structure in each is presented, together with information on the most species-rich spider families occurring in the biome.

Effects of a fast-burning spring fire on the ground-dwelling spider assemblages (Arachnida: Araneae) in a central South African grassland habitat

Fire is widely used as a management strategy in grasslands to maintain vegetation structure and improve grazing quality for large herbivores. The impacts of burning on invertebrates in South Africa remain poorly understood. A study was initiated in spring 2005 to determine the impact of a fast hot burn on ground-dwelling spider assemblages in a grassland habitat in the central Free State. Pitfall traps were set out at six sites in the reserve, with three sites each in the burnt and unburnt areas, to sample spiders over a 12-month period. A total of 5 253 spiders were collected, representing 33 families and 120 species. Spider abundance was significantly lower in the burnt (n = 1 956) than unburnt sites (n = 3 297), and burnt sites had, on average, considerably fewer species than unburnt sites. The dominant families in the burnt sites were Lycosidae (29.5%), Gnaphosidae (16.9%), Ammoxenidae (9.6%) and Zodariidae (5.7%), whereas Ammoxenidae (22.7%), Lycosidae (20.6%), Gnaphosidae (15.3%) and Amaurobiidae (10.2%) dominated the unburnt sites. Of the nine most abundant families collected, only Caponiidae were more abundant in the burnt than unburnt sites. Our data suggest that fast-burning hot spring fires cause a considerable initial post-fire decline in spider abundance, and have a negative influence on the abundance as well as the resistance of assemblages to disturbances other than fire (e.g. rain). However, most of the dominant families had abundances comparable to unburnt areas within a year post-burn.

Notes on the biology of the wasp, Chalybion spinolae (Hymenoptera: Sphecidae), an obligatory predator of Latrodectus (Araneae: Theridiidae) spiders in South Africa

Some aspects of the biology of the wasp Chalybion spinolae are documented. This includes behaviour relating to life cycles, nesting, mating, oviposition and prey interaction of this wasp. The physical appearance of the wasps and their prey are described and some measurements are given. The prey of C. spinolae are two species of spiders, Latrodectus indistinctus and Latrodectus geometricus (Araneae: Theridiidae). The observations spanned a period of 5 years, and involved approximately 200 wasp nests. This study serves to provide more observational information about the biology of the wasp and its predatory behaviour.

Animal taxa contrast in their scale-dependent responses to land use change in rural Africa

Human-dominated landscapes comprise the bulk of the world’s terrestrial surface and Africa is predicted to experience the largest relative increase over the next century. A multi-scale approach is required to identify processes that maintain diversity in these landscapes. Here we identify scales at which animal diversity responds by partitioning regional diversity in a rural African agro-ecosystem between one temporal and four spatial scales. Human land use practices are the main driver of diversity in all seven animal assemblages considered, with medium sized mammals and birds most affected. Even the least affected taxa, bats and non-volant small mammals (rodents), responded with increased abundance in settlements and agricultural sites respectively. Regional turnover was important to invertebrate taxa and their response to human land use was intermediate between that of the vertebrate extremes. Local scale (< 300 m) heterogeneity was the next most important level for all taxa, highlighting the importance of fine scale processes for the maintenance of biodiversity. Identifying the triggers of these changes within the context of functional landscapes would provide the context for the long-term sustainability of these rapidly changing landscapes.