Gemmula amabilis: The taxonomy of this species is rather confused. The name amabilis had long been unused until Powell (1964) applied it to shells from the JME material (the specimen from the John Murray Expedition stn 176 figured by him (Powell. 1964. p. 200. fig. 1) was not found). However, Powell expressed some doubts on the identification of John Murray Expedition specimens as G. amabilis, having indicated certain differences from the sketchy and rather inadequate original figures.
Kilburn (1983) reported that the types of Pleurotoma amabilis were probably lost and therefore the name amabilis must remain a nomen dubium. He also compared the specimen figured by Powell with G. pulchella Shuto, 1961 from the Pliocene of Japan. The latter species is characterized by smaller and much more numerous gemmules (29 on the body whorl of 10.2 mm holotype and up to 34 at the shell height of 26.57 mm - Shuto, 1965).
Later on Kosuge (1990 1992) used the name amabilis for North-Western Australian shells and at the same time mentioned that Powell's specimen differs from the original drawings and. as far as it can be judged from the text (Kosuge. 1990, p. 154), may not be conspecific with amabilis. The shells figured by Kosuge as G. amabilis, actually resemble G. gemmulina (von Martens, 1902) sensu Powell. 1964 more in the shell outlines and the character of spiral sculpture of alternating primary cords and intermediate threads. The latter species is distributed from Taiwan to Indonesia (Powell. 1964), which is far closer to North-Western Australia than the Red Sea and the Gulf of Aden.
Despite the obviously ambiguos status of the name amabilis, it seems reasonable to conserve its application to the Gulf of Aden shells similar to those described by Powell, because no other available name for them exists. Perhaps, the examination of a large series of the Red Sea Gemmula, especially from the type locality of amabilis. would clear up the question of proper application of the name. The specimens of G. amabilis are characterized by a small slender shell (up to 25.9 mm, usually 22-25 mm) with more or less channelled sutures, a moderately developed subsutural fold covered by 1-3 riblets, 2-3 prominent and widely spaced cords on the upper shell base without intermediate threads, few (usually two) thin threads on the subsutural slope, and 16-24 peripheral gemmae on the body whorl (usually 22, mean 20.7 at the shell height 18.2-25.9 mm: the number of gemmae does not show a strict correlation with the shell height). This deep-water species, due to its small size, can be confused with young specimens of other species of Gemmula. However, the presence of the 'tertiary' apertural notch (characteristic for mature individuals of Gemmula - see Kantor & Sysoev, 1991) in one of the shells (H = 20.2) indicates that the mentioned shell size characterizes adult specimens of G. amabilis.

Gemmula amabilis: Shell rather small for the genus; elongate, rather narrow fusiform; spire whorls tall, turreted with straight siphonal canal, which is rather short and about a half of the spire whorls; each whorl sharply angulated at the middle and 12 to 13 in number, of which three constitute the protoconch. Suture defined with narrow striate line. Spire whorls sharply angulated with a granulated keel, which situated at the middle of each whorl and forms steep slopes on both upper and lower directions; granules rather large, somewhat laterally compressed, and connected and overriden with two to three spiral cords, it numbers about 20 to 23 in each whorl; four to five spiral threads encircled between suture and angulated keel and three threads below the keel; body whorl bears three spiral threads and intermediate ones; base bears 16 to 17 spiral threads to the tip of the siphonal canal. Whole surface roughly sculptured with growth striae, forming lamellate appearance on the interspaces between spiral threads. Outer lip simple with wide. V-shaped sinus. Color pale yellowish white with pale brownish tint on the angulate keel.
Powell (1964) confined the distribution of this species in the area of Red Sea and figured the specimen from off Aden (732 m deep ex from John Murray Expedition) as identical with this species, but his specimen differs from the original figures in its contour of shell shape and rather large granules on the peripheral keel. The present material also similar to G. ryukuensis MacNeil, 1960 in its shell shape and sculpture, but it differs in its coarser spiral threads on the subsutural slope, equal sized spiral threads on the body whorl and smaller sized shell.
Localities and measurements of the present material: Shell height 26.0 mm; Breadth 9.3 mm.
20-30 mm.(variation height)

Gemmula amabilis: North-western Indian Ocean, 494-2000 m; also probably from north-western Australia, 300-496 m.