Paper Title
Diversity and Structure of Spider Assemblages in Sirumalai Hills, Dindigul District, Tamilnadu
Abstract
A pilot study was conducted to reveal the spider diversity in Sirumalai hills of Dindigul district. The study was
conceded out in Sirumalai Hills which is the western offshoot of the Eastern Ghats, lying between 10°07' - 10°18' N latitude
and 77°55' - 78°12'. The annual rainfall is around 1200 mm per year, with approximately 75 rainy days in two seasons. The
maximum rainfall is recorded from the North-East monsoon (October-November). April- June is noted as the hot summer
season. The humidity is maximum in the rainy months (91%) and minimum in the summer months (68%). A total of 112
species of spiders belonging to 78 genera of 35 families were collected from this area during this study period (June 2014-
May2015). The maximum and minimum temperatures were recorded in the months of May (29.2°C) and January (18.3°C)
respectively. This represents 10% of the total families recorded in India. Guild structure analysis of the collected spiders
revealed 6 feeding guilds viz., orb-web builders, foliage hunters, ground hunters, sheet web builders, scattered line weavers
and ambushers. The families Araneidae, Tetragnathidae, Salticidae and Thomisidae exhibited maximum species diversity.
The dominant family was Araneidae with 17 species. Shannon index, Simpson index, and Margalef Richness index
evaluated were 1.06, 0.103 and 8.4 respectively. Spiders belonging to different feeding guild and population were higher
during monsoon and winter season. Because of the complex interaction of various climatic factors such as high rainfall and
humidity, with topographical features, Sirumalai hills holds many smaller but diverse environmental niches which make this
an important centre of speciation in Eastern Ghats.
Keywords - Spider diversity, Eastern Ghats, Sirumalai Hills, Araneidae