Isela inquilina is a small spider, with body lengths ranging from 1.7 to 2.2 millimeters. Its
carapace is brownish and displays darker striae, while the
sternum is a dull greyish color with a dark border. The legs have a brown-yellow hue, and the abdomen can appear greyish or creamy, often covered in long hairs. In males, total body length varies from 1.70 to 1.83 millimeters. The carapace is longer than it is wide, adorned with a row of dorsal spines and a subtle depression in front of the posterior median eyes. The arrangement of the eyes is circular, with the anterior median, anterior lateral, and posterior lateral eyes grouped closely, while the posterior median eyes are spaced apart. The male
palpus features an elongated tibia that ends with a notable row of long, flat spines. The cymbium has a relatively simple structure with a stout thorn, and the
embolus is needle-like, spiraling toward the apex. Females are slightly larger, measuring between 2.00 and 2.22 millimeters in total body length. Their carapace dimensions range from 0.83 to 0.93 millimeters in length and 0.67 to 0.73 millimeters in width. The vulva features short copulatory ducts, with their openings positioned deep beneath the epigastric plate. The retrolateral diverticulae are long and coiled, while the spermathecal duct is also long and coiled. The
type locality for
Isela inquilina is
Kilifi, Kenya. Specimens were collected on several dates, including 31 August 1977, 8 September 1977, 16 September 1977, and 9 August 1980. The types are currently held at the
British Museum of Natural History, the
Royal Belgian Institute for Natural Sciences, and the
Royal Museum for Central Africa. == Habitat and ecology ==