Mecistocephalus angusticeps

The species M. angusticeps has only 47 pairs of legs and reaches 50 mm in length. The body is mostly yellow, with fine dark pigmentation on the dorsal surface, but the head and most anterior segments are a reddish brown. The head is longer than wide, with a length/width ratio of about 1.7 or 1.8, and the antennae are three times as long as the head is wide. The dorsal surface of the head features a transverse frontal line that is uniformly concave forward. The pleurites on the side of the head (buccae) feature setae on the posterior half only. The areolate region in the anterior part of the clypeus includes a rounded area in the middle with finer areolation. The areolate part of the clypeus also features about six setae in a transverse band and another pair of setae to the rear near the middle of the posterior margin, just in front of the smooth part of the clypeus. The mandible features about seven pectinate lamellae (comb blades), with about six teeth on the first lamella and about eleven teeth on the average intermediate lamella. The second maxillae are slender, each with a claw that tapers uniformly to a pointed tip. The first article of the forcipules features a small proximal tubercle and a similar distal tubercle, the intermediate articles each feature a small tubercle, and the ultimate article features only a shallow emergence at the base. …

The French zoologist Henri Ribaut first described this species in 1914 based on a single adult female specimen found in 1911 in one of the Shimoni caves at sea level on the coast of Kenya. Ribaut originally described this species under the name Lamnonyx angusticeps. In 1920, the American biologist Ralph V. Chamberlain moved this species to the genus Mecistocephalus. Since then, this species has been found on several islands in the Indian Ocean. Finds have been recorded on islands in Seychelles (on Curieuse island, on Praslin island, and on Picard island and elsewhere on the Aldabra atoll) and on the Egmont Atoll in the Chagos Archipelago.