Description: Shell small to medium-sized, SL up to 25 mm, turriform, with up to seven to eight teleoconch whorls with prominent shoulder and moderately long (0.22 0.23 of SL), straight or slightly recurved, siphonal canal. Suture shallowly impressed or narrowly channelled (Powelligemmula sp. 02). Protoconch with up to 4 + whorls, first 1.5 whorls smooth, later whorls sculptured with axial riblets. Subsutural cord moderately developed to rather strong, spanning at least half of subsutural ramp width, bearing one to three spiral ridges, central strongest (Powelligemmula sp. 02). Subsutural ramp distinctly concave, either without spiral cords or with two narrow spiral cords below subsutural cord. Peripheral cord at least as strong as subsutural one, forming prominent shoulder angle, gemmate; gemmae nearly orthocline, shallowly bifid, around 25 on last whorl, distinct on entire shell; intervals with two feeble spiral threads. Last whorl with five to six distinct, unevenly spaced, major cords below shoulder; rarely with smaller cordlets between major cords. Siphonal canal with distinct, uniform, more closely spaced cords. Aperture (without canal) 0.23 0.24 of SL. Anal sinus deep, narrow, on peripheral cord. Shell ground colour white, sometimes with irregularly shaped and placed orange blotches, rarely ground colour orange with lighter peripheral cord. Radula: marginal teeth shoe-shaped. Central formation well-developed, with rectangular base and long, narrow cusp.

Etymology: The genus is named after Arthur William Badén Powell (1901—1987), eminent New Zealand malacologist and the author of numerous publications on Conoidea, including classification and generic revision of Recent and fossil conoideans and monographs of Indo-Pacific turrids, and at the same time referring to the overall similarity of the new genus to the earlier broader concept of Gemmula.

Remarks: There are two broadly distributed and rather variable non-sister Powelligemmula species that fit the definition of Powelligemmula rarimaculata . None of the sequenced specimens of these two species was collected close to the type locality (Sagami Bay, Japan), and therefore, it is uncertain which one represents the true P rarimaculata. Therefore, we refer to them as Powelligemmula cf. rarimaculata 1 and Powelligemmula cf. rarimaculata 2. They are sympatric and even syntopic in the South China Sea, New Caledonia, the Coral Sea and Papua New Guinea, and their depth ranges overlap. One of them (Powelligemmula cf. rarimaculata 2) also extends to Mozambique and Madagascar.
One subadult specimen (MNHN-IM-2007-40818) from Panglao Island, Philippines that was included in the exon-capture analysis is remarkably similar to Eugemmula monilifera both in colouration (orange ground colour and white peripheral cord) and sculpture pattern. We refer to it as Powelligemmula sp. 01. In both the exon-capture-based tree and in the COI-based tree, it forms a sister group to P. cf. rarimaculata 1 with high support. Nevertheless, we should mention that the sculpture pattern is similar in Powelligemmula and Eugemmula.
Powelligemmula is most similar to Mcleanigemmula, differing in a less pronounced subsutural cord and a more pronounced central formation of the radula, with a more distinct pointed central cusp. There is also conchological similarity to Oliveragemmula, although the subsutural cord in Powelligemmula is not highlighted by orange as in the latter genus.

Distribution: Indo-Pacific, from Mozambique and Madagascar to the Philippines, the South China Sea and Japan (P rarimaculata), Papua New Guinea, the Coral Sea and New Caledonia; 100 1,000 m, mostly 200-500 m.