The Echinoid Directory

Arachniopleurus Duncan & Sladen, 1882, p. 42

[Radiocyphus Cotteau, 1890, p. 98, type species Radiocyphus villanovae Cotteau, 1890]

Diagnostic Features	Test depressed, flattened above and below. Apical disc not preserved; larger than peristome. Ambulacra straight, relatively wide. Plating polygeminate with 3 elements united by a primary tubercle alternating with one or two simple elements, All elements reaching the perradius, the lowest being the largest. Pore-pairs uniserial throughout; no phyllodes. Interambulacral plates wider than tall, with large, centrally placed primary tubercle. On adradial and interradial sides there is a radiating and reticulate ornamentation of ridges. Primary tubercles perforate and crenulate. Strong radial ornament of thin clacite ridges surrouding the primary tubercles. Peristome small and deeply sunken, with well defined buccal notches that are deep and wide. Lantern and spines unknown.
Distribution	Eocene, Pakistan, Spain.
Name gender	masculine
Type	Arachniopleurus reticulatus Duncan & Sladen, 1882, p. 43, by original designation.
Species Included	A. reticulatus Duncan & Sladen, 1882; latest Palaeocene - Lower Eocene, Pakistan. A. villanovae (Cotteau, 1890); Middle Eocene, Spain.
Classification and/or Status	Euechinoidea, Camarodonta, Glyphocyphidae. Presumed monophyletic.
Remarks	Distinguished from other glyphocyphids by its highly sculpted test and polygeminate ambulacral compounding. Duncan, P. M. & Sladen, W. P. 1882. The fossil Echinoidea from the Ranikot series of Nummulitic strata in western Sind. Palaeontoligica Indica 14th Series1(3), 21-100, pls 5-20.