Antenna 2 without swimming setae, flagellum biarticulate; mandibular palp tri-articulate with one seta on terminal article; molar present; outer lobe of maxilliped larger than inner lobe; gills on pereonites 3 and 4; pereopods 3 and 4 two-segmented, pereopod 5 two- or three-segmented; abdomen of male with one pair of appendages and one pair of lobes, of female with one pair of lobes.
Caprellid, “Ghost” or “Skeleton” shrimps, so called for their skeletal appearance. Amphipod crustaceans, easily distinguished by the elongate stick-like body form and reduction of the abdominal appendages. Head is generally fused with pereonite 1. Pereopods on first 2 segments (pereonites) are most flexible and called gnathopods; gnathopods 2 being the largest, used in defense, feeding and substrate attachment. In many species pereopods 3 and 4 may also be reduced or absent. Gills on pereonites 3 + 4, rarely on pereonite 2. Pereopods 5 - 7 much smaller than 1 + 2, used for clinging to the substratum. In females, brood plates (öostegites) develop on pereonites 3 + 4. Much remains to be learnt about their biology, ecology and in many cases changing distributions.
Laubitz (1970) suspects this to be the same as Mayer’s genus Incertum (1903). The only difference being the absence of the mandibular palp in Mayer’s single specimen. However, the mandibular palp is frequently not observable in Mayerella unless the mandible is dissected; the palp is either held very close to the head or is easily lost.
