Spider assemblages associated with leaf litter of three tree species in central South Africa (Arachnida: Araneae)

Abstract

Spiders were collected by sifting leaf litter of three common tree species, Cussonia paniculata sinuata, Olea europaea africana and Searsia lancea, in an undisturbed grassland habitat in central South Africa. The study aimed to collect baseline data on spider assemblage structure, seasonality and the effects of litter structure on spider assemblages. In total, 1385 spiders were collected, representing 26 families and 56 species. Four species, Obatala sp. (Amaurobiidae, 22.7%), Camillina maun Platnick & Murphy (Gnaphosidae, 17.0%), Proevippa sp. (Lycosidae, 11.4%) and Zelotes frenchi Tucker (Gnaphosidae, 9.2%) dominated the fauna. Spider abundance was the highest in Olea litter (n = 607), followed by Searsia (n = 453) and Cussonia (n = 325). Searsia had the greatest number of species (41 spp.), followed by Olea (35 spp.) and Cussonia (30 spp.). Both spider abundance and species richness per sample varied significantly between the tree species. Of the ten most abundant species, all but two showed a significant preference for particular litter types. Mean spider abundance and species richness per sample were the lowest in Cussonia litter, which was the deepest litter type, but with the most interstitial space, whereas mean abundance and species richness per sample were the highest in Olea litter, which was the shallowest and moderately compact in structure. RésuméDes araignées furent collectées en tamisant de la litière de feuilles de trois espèces d'arbres communes, Cussonia paniculata sinuata, Olea europaea africana et Searsia lancea, dans un habitat de prairies intact du centre de l'Afrique du Sud.L'étude visait à récolter des données de référence sur la structure des assemblages d'araignées, sur leur saisonnalité, et sur les effets de la structure de la litière sur les assemblages d'araignées. Au total, 1 385 araignées ont été collectées, représentant 26 familles et 56 espèces. Quatre espèces Obatala sp. (Amaurobiidae, 22,7%), Camillina maun Platnick & Murphy (Gnaphosidae, 17,0%), Proevippa sp. (Lycosidae, 11,4%) et Zelotes frenchi Tucker (Gnaphosidae, 9,2%) dominaient la faune. L'abondance des araignées était au maximum dans la litière d'Olea (n = 607), suivi de Searsia (n = 453) et de Cussonia (n = 325). Searsia comptait le plus grand nombre d'espèces (41 spp.), suivi par Olea (35 spp.) et par Cussonia (30 spp.). L'abondance des araignées et la richesse en espèces par échantillon variaient significativement entre les espèces d'arbres. Parmi les dix espèces les plus abondantes, toutes sauf deux montraient une préférence significative pour des types de litière particuliers. L'abondance moyenne des araignées et la richesse moyenne en espèces par échantillon étaient plus faibles dans la litière de Cussonia, qui était le type de litière le plus profond mais avec le plus d'espaces interstitiels, alors que l'abondance moyenne et la richesse moyenne en espèces par échantillon étaient les plus hautes dans la litière d'Olea, qui est aussi la plus mince et dont la structure est modérément compacte.

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

“…The PAs include nature reserves, a national park and a botanical garden. Published records include surveys in the Free State National Botanical Gardens (Butler & Haddad 2011;Neethling & Haddad, 2013) and the Erfenis Dam Nature Reserve (Fourie et al, 2013), while surveys are presently underway in the Kalkfontein Dam Nature Reserve (Josling & Lotz, 2014), Amanzi Private Game Reserve (Butler & Haddad, 2014) and Amohela-ho-Spitskop Conservancy .…”

“…An illustrated guide to the spiders of the Grassland Biome is also available (DippenaarSchoeman & Haddad, 2014). Grassland survey results have focused on the Free State (Lotz et al, 1991;Haddad & Dippenaar-Schoeman, 2002Haddad, 2005;Butler & Haddad, 2011;Fourie et al, 2013;Neethling & Haddad, 2013), Gauteng (Van den Berg & Dippenaar-Schoeman, 1991b), Mpumalanga , Eastern Cape (Dippenaar- and KwaZulu-Natal provinces (Van der Merwe et al, 1996). Spiders have also featured in studies using functional feeding groups as indicators of habitat quality (Kaiser et al, 2009) and taxonomic surrogates (Buschke & Seaman, 2011), and burning effects on invertebrates (Uys et al, 2006;Little et al, 2013).…”

“…They sampled arthropods from only two microhabitats (a fallow area and a lawn) on a single occasion, using small pitfall traps, sticky traps, a malaise trap and sweep netting. A third botanical garden sampled is the periurban Free State National Botanical Gardens, where staff and students of the University of the Free State and National Museum in Bloemfontein have collected extensively, including intensive surveys from the leaf litter and foliage strata (Butler & Haddad, 2011;Neethling & Haddad, 2013). Pryke & Samways (2009) investigated the invertebrate response (including spiders) to alien pine plantations, their removal in comparison with natural vegetation, recovering indigenous forests and Kirstenbosch Botanical Garden around Cape Town.…”

“…The results suggest that habitat structure, such as branch size and epiphytic lichen abundance, can explain the greater number of spiders in lichen-rich patches of the island (Mukherjee et al, 2010). Butler & Haddad (2011) investigated the spider assemblages in the leaf litter of three tree species in the central Free State. They found significant differences in both species richness and abundance of spiders between the three tree species.…”

Impact of Habitat Complexity on Body Size of Two Spider Species, Alopecosa cuneata and A. pulverulenta (Araneae, Lycosidae), in River Valley Grasslands

“…They occur in large numbers in most habitats and they are very sensitive to habitat structure and microclimatic conditions [18]. Many studies have shown that complexity and structure of habitat (which often comes down to vegetation structure and density) had a significant influence on the abundance, species richness, and distribution of spiders [19][20][21][22][23]. Despite the great number of research on spiderhabitat interactions, only limited studies have included body size.…”