Assemblage of spider diversity in Okkarai region of Pachamalai hills, Eastern Ghats, Tiruchirappalli district, Tamil Nadu, India

Abstract

The Okkarai area of Pachamalai hills, Eastern Ghats, Tiruchirappalli district, Tamil Nadu, India, was studied for spider diversity in the current study. In total, 178 spiders were recorded, belonging to 12 distinct families (Araneidae, Desidae, Linyphiidae, Nephilidae, Oxyopidae, Pholcidae, Pisauridae, Salticidae, Sparassidae, Tetragnathidae, Theridiidae and Thomisidae), and 17 and 20 different genera and species, respectively. Araneidae family dominated the spider population, and the family dominance curve was in the ascending order of Araneidae (25.28%) > Oxyopidae (14.04%) > Pholcidae (14.04%) > Thomisidae (10.11%) > Tetragnathidae (7.86%) > Linyphiidae (6.74%) > Nephilidae (6.17%) > Sparassidae (5.05%) > Theridiidae (4.49%) > Pisauridae (3.37) > Salticidae (2.24%) > Desidae (0.56%). Araneidae (17.64%) had the most genera per family, and Araneidae and Oxyopidae (20.00%) had the most species per family; and about species composition, Pholcus phalangioides dominated with 14.04%. Spider guilds were represented by web patterns as well as hunting patterns. Web pattern comprised orb web (60.86%), cobweb (34.78%) and sheet web (4.34%). Orb web was represented by families Araneidae, Nephilidae and Tetragnathidae; cobweb by Desidae, Pholcidae, Pisauridae and Theridiidae; while Linyphiidae for sheet web. Ambushers (53.22%) and stalkers (46.77%) represented the hunting pattern whereas Pisauridae, Sparassidae and Thomisidae represented ambushers, and Oxyopidae and Salticidae represented stalkers. Araneidae and Oxyopidae had high species richness indicated by Hill’s (4), Margalef’s (1.33), and Menhinick’s (0.299) indices. Salticidae had high species evenness denoted by Alatalo’s (0.578), Pielou’s (0.488), Shannon’s (1.471) and Sheldon’s (1.413) indices; while Linyphiidae represented Heip’s index (1.347). Araneidae scored high on other indices, viz., Berger-Parker dominance (25.28%), community dominance (1.24), and relative dominance (20.00%); while Salticidae had a high Hill’s number abundance (1.413%), and Pholcidae had a high relative frequency (0.55). This study will contribute to the data on spider biodiversity, taxonomy, it's abundance, distribution, and community organization.