“Cactus hedgehog (or urchin) with grooves (or furrows)”, characterizing both the spiny character of the genus, and the fact that it has strongly grooved ribs.
A genus of low-growing, rather small plants, globose flattened to shortly cylindrical, usually solitary, sometimes weakly caespitose, with ribs often numerous (up to 120), fine and wavy, with few areoles, usually widely spaced. Spines o two types: the upper ones thicker, longer, often dagger-shaped, the lower, smaller, often hyaline.
Flowers diurnal, rather small, appearing at the apex of stems, with a short floral tube, whitish, yellow or more often pink purple to purplish violet, striped purple or brown, pollinated by insects, especially bees (Ceratina sp. among others). Fruits rather small, globose, bearing scales, laterally dehiscent. Seeds subglobose, blackish-brown, shiny, reticulate, dispersion probably myrmecophilous (ants).
The genus Echinofossulocactus grows mostly at ground level, very mimetic, mostly in the shade of grasses, bushes and shrubs, in mountains, on stony plains, grasslands rich in humus and with a rainy season, on rocky soils, between limestone rocks in cracks, in association with a rich succulent flora (other cacti, Bromeliads, Agaves etc.), from 600 up to 2800 m in altitude.
Mexico (Aguascalientes, Chihuahua, Coahuila, Durango, Guanajuato, Hidalgo, Jalisco, Mexico DF, Nuevo Leon, Oaxaca. Puebla, Queretaro, San Luis Potosi, Tlaxcala, Zacatecas).
Currently considerably reduced to 12 species, obviously still to debate:
– Echinofossulocactus coptonogonus* (Lem.) Lawr. 1841
– Echinofossulocactus crispatus* (DC.) Lawr. 1841
– Echinofossulocactus dichroacanthus* (Mart, ex Pfeiff.) Britton & Rose 1922
– Echinofossulocactus lamellosus (A.Dletr.) Britton & Rose 1922
– Echinofossulocactus multicostatus* Hlldm. ex K.Schum.) Britton & Rose 1922
– Echinofossulocactus lloydii* Britton & Rose 1922
– Echinofossulocactus obvallatus* (DC.) Lawr. 1841
– Echinofossulocactus ochoterenanus* (Tlegel) H.C.Whltm. 1934 (= E. heteracanthus ?)
– Echinofossulocactus pentacanthus* (Lem.) Britton & Rose 1922
– Echinofossulocactus phyllacanthus* (A.Dietr. & Otto) Lawrence 1841
– Echinofossulocactus sulphureus Whitm . 1934
– Echinofossulocactus vaupelianus* (Werderm.) H.C.Whltm. 1934
References: "TAXONOMY of the CACTACEAE" - ISBN 978-84-617-3723-9 (Vol. 1)