SPECIES DIVERSITY OF EARTHWORMS JOSEPH SARWUAN TARKAA UNIVERSITY MAKURDI, BENUE STATE NIGERIA

ABSTRACT This study investigated the species diversity of earthworms in Joseph Sarwuan Tarka University Makurdi. Earthworms was collected from the soil using a hand-sorting method. This was done by making a quadrant with a measurement of 100cm length and 100 cm width. 0.5% formalin was poured on the marked soil after which a depthof 30cm was dug using a spade and earthworms will be collected using forceps. Earthworms first of all segregated according to age and species by hand sorting.The earthworms were identified using the descriptions of Sims and Gerrard as well as with the assistance of an authority at the Department of Zoology. Earthworm species was numbered serially and fundamental field data including habitat, locality, soil texture, colour and vermin-composition observed. Clitellate individuals was examined by noting morphological parameters such as the length of the body, the skin colouration, the diameter of the body, the clitellum position,the number of total body segments, and the type of prostomium. The result revealed ecological and morphometric variations among Lumbricus rubellus, Eisenia fetida, and Aporrectodea longa across four sampled sites,revealing habitat-adaptive features.Aporrectodea longa was the longest species, reaching up to 27 cm, while Lumbricus rubellus ranged from 22 to 29 cm. Clitellum position, a key indicator of maturity, varied, with Aporrectodea longa showing the highest positions (14 17 segments) across sites. Tail morphology differed: Lumbricus rubellus had a dark clitellum and reddish tapered tail, Eisenia fetida displayed a yellow clitellum and rounded tail, and Aporrectodea longa had a pink-red clitellum and cylindrical tail, suggesting species-specific habitat adaptations. Physicochemical soil analysis revealed pH levels consistently slightly acidic to neutral (6.81-6.84) across sites, optimal for earthworm activity. Soil temperatures ranged from 26.3°C in Ujam Village to 29.1°C in the North Core, potentially impacting metabolic rates.Soil colour varied, with darker, organic-rich soils in the South Core and Ujam Village, correlating with increased organic matter and moisture levels (up to 2.28% and 26.16%, respectively). The North Core, with lower organic (2.24%) and moisture content (23.16%), may restrict earthworm presence,while Ujam Village offers the most favourable conditions. These findings emphasize the influence of specific soil properties on earthworm distribution and adaptation across different environments. It was recommended that further studies should be conducted on the effect of seasonal changes on soil physiochemical parameters and earthworm eco-morphology to gain deeper insights into temporal adaptation mechanisms and genetic variability among earthworm species across habitats should be carried out to understand how morphological traits evolve in response to different ecological niches.