There is always something new. This fundamental rule in conchology is certainly correct, even for species that we all believe are well understood and about which all seems said and written down. One of these species is Monetaria annulus, about which innumerable studies have been published, which hardly varies throughout its range and whose biology and distribution is among the most comprehensively worked on subjects. So now, I got this batch of shells coming from Aden, Yemen, where they were collected intertidally. These shells show conchological characteristics not encountered in other populations. The shells are rhomboid or nearly spherical, extremely depressed, the margins are greatly produced and separated from the dorsum by a step that encircles the dorsum. One may argue that among thousands of annulus there is always one that fits to this description, but in the case of the shells from Aden, most specimens more or less show these characteristics. At times when things get named even though they do not differ in any way at all, I feel that this annulus from Aden could have its own name, may be as a form. I am not going to describe it, no worries, but I wanted to point this interesting bit of news out to my readers.
(Important note: the name dilatissimus is not valid, not a synonym, it is merely used here for communication among Annulusists).

Three well developed specimens of M. annulus f. dilatissimus. 22-25 mm