The genus Gemmuloborsonia, previously considered as extinct, now appears to be rather widely distributed through the Indo-Pacific. A similar species, probably belonging to this genus, was recorded and figured by Azuma (I960) from off Tosa. Japan, in 100 fins, as 'Hemipleurotoma (?) abesigerui Kuroda (MS)'. However, the name is a nomen nudum and thus unavailable. Later the name was listed by Higo & Goto (1994) as Kuroshioturris abesigerui Kuroda, MS. but these authors also did not provide any diagnosis to validate the name. Unfortunately, the photograph given in the paper by Azuma is too poor to discuss the relationship between this species and other representatives of the genus.
Another species, similar in shell outline to Gernmuloborsonia, is Pleurotoma optata Smith. 189? (non Harris. 1897; = indagatoris Finlay. 1927). However, judging from the figure (Alcock & McArdle. 1901), the species lacks a columellar pleat. The taxonomic position of this species remains unclear. Finlay (1927) included it into Gemmula, whereas Powell (1964) with some doubt considered it to be a member of Lucerapex Iredale, 1936. Recently Robba et al. (1989) recorded this species from the Early Pleistocene of Timor (Indonesia). The illustrated shell (Robba et al., 1989, pl. 4. figs 6a. 6b) undoubtedly belongs to Gernmuloborsonia and seems to be closely related to G. moosai. However, its identity with indagatorius is questionable, because the original figure of that species (Alcock & McArdle, 1901, pl. 9. figs 1,1a) shows obsolete subsutural tubercles on the body whorl, whereas on the spire whorls the subsutural tubercles are connected with gemmules on the peripheral keel by oblique folds. The latter character has not been observed in any species of Gemmuloborsonia.
The genus Gemmuloborsonia probably derived from Gemmula-like turrine ancestors, and later acquired a convergent similarity to clathurelline genera. This suggestion is particularly supported by the fact that the Miocene species differ from the Plio-Pleistocene and Recent ones in having weakly gemmulated or plain subsutural cord, and bear more resemblance to typical Gemmula than to any clathurelline genus. If we assume that a multispiral protoconch is a plesiomorphic character state and a paucispiral protoconch is apomorphic, then the occurrence of a multispiral protoconch in Recent species of Gemmuloborsonia indicates that this genus diverged from Gemmula before the loss of planktotrophy. Consequently, we can expect that fossil species with multispiral protoconchs will be also discovered in future.
The presence of columellar pleats had long been considered a landmark of the 'borsoniid' and 'bathytomid' groups of genera of the subfamily Clathurellinae. Therefore, the case of convergent appearance of this character in Gemmuloborsonia is of particular interest. Specifically, this may require a reevaluation of application of this character in assigning some genera to the family-group taxa. A similar case of presence of columellar plication in the crassispirine genus Buridrillia was recently described by Emerson & McLean (1992).
The occasional presence of some sort of sculpture on the columella is also characteristic of Gemmula congener (Smith, 1894). The presence of a kind of nodule or swelling on the upper part of the columella in some specimens was mentioned by the author of the species (Smith. 1894. p. 160). Later the same feature was recorded by Schepman (1913) and Robba et al. (1989). Through the courtesy of R. Moolenbeek of the Zoologisch Museum, Amsterdam, we had an opportunity to examine the material described by Schepman. One of the two shells from 'Siboga' sta. 139 (shell height 50.6 mm) has a low but rather wide and rounded fold encircling the upper part of the columella. It is very similar to that of the shell illustrated by Robba et al. (1989. pi. 3, fig. 2a). However the appearance and position of this fold is quite dissimilar from the columellar pleats found in Gemmuloborsonia and representatives of Clathurellinae.
Differences in the protoconch morphology (i.e., multispiral or paucispiral protoconchs) in the Conoidea have long been considered as (he basis for separating genera and subgenera. However, it is presently recognised that the number of protoconch whorls, indicating the type of larval development, is not a character of major taxonomic significance at supraspecific levels (Bouchet, 1990). The presence of two protoconch types in Gernmuloborsonia in fact reflects only the difference between planktotrophic and non-planktotrophic development, because the protoconchs actually differ only in the extent of the part with arcuate axial ribs. This part is present in both protoconch types and marks the transition from protoconch I to teleoconch.

Genus Gemmuloborsonia Shuto, 1989
Type-species Gemmuloborsonia fierstinei Shuto, 1989 (original designation)
From our new data, the original diagnosis of the genus should be supplemented as follows. The protoconch is either paucispiral, of about 1.5-2 whorls, globose, smooth or with minute granules arranged in spiral rows, with brephic, arcuate, axial ribs just before the transition to the teleoconch; or multispiral, protoconch I consisting of 1.7 whorls with a sculpture of minute granules, protoconch II of 1 -1.5 whorls sculptured by strongly arcuate axial ribs not reaching the abapical suture. The operculum is narrow, leaf-shaped, with a terminal nucleus. The radula consists of central and marginal teeth. The central tooth is weak, but with a prominent spine-like centre cusp. Marginal teeth are of wishbone type, robust, with a short and broad accessory limb.

Distribution. Plio-Pleistocene- of the Philippines, Upper Miocene and Early Pleistocene of Indonesia, and Upper Miocene of Italy. Recent species recorded from the upper bathyal of Eastern Indonesia, New Caledonia, Mozambique Channel, and the Philippines.

Diagnosis: Shell small, to medium-sized, 25-45 mm, fusiform to broad fusiform, of more than 10 teleoconch whorls, with siphonal canal straight, broad and short relative to aperture. Suture from distinctly impressed to narrowly channelled in species with strong subsutural cord. Protoconch, when multispiral of up to 3.5 whorls with about 1.5 upper whorls smooth or micro-shagreened and later whorls with arcuate ribs; when paucispiral of 1.5-2 smooth or micro-shagreened whorls with few arcuate axial ribs at transition to teleoconch. Subsutural cord varying in strength, occupying half of subsutural ramp, or broader, at least on first teleoconch whorls. Subsutural cord sometimes very strong, bulging and occupying nearly the entire subsutural ramp, which in this case is reduced to groove between subsutural and peripheral cords. Subsutural cord gemmate at least on first whorls. In addition to the invariably gemmate major ridge of the cord, smaller ad- and abapical ridges sometimes present. Interval between subsutural and peripheral cords sometimes bearing additional spiral cordlets. Peripheral cord equal with or weaker than subsutural one, gemmate, usually form¬ing weak shoulder angle. Gemmae narrow, rather broadly spaced, orthocline or weakly prosocline, sometimes bi- or tripartite, 22-42 on last whorl. On the last whorl of large specimens, gemmae on peripheral and subsutural cords often become obsolete. Base of last whorl with spiral cords of uneven strength, from weak to very strong and nodulose. Siphonal canal with distinct uniform cords, usually more closely spaced and weaker than on shell base. Aperture narrowly ovate, extending into moderately long and broad canal. Anal sinus moderately deep, on peripheral cord. Shell uniformly greyish with greenish tint, in some species with irregular brown spots.
Radula : marginal teeth shoe-shaped with long anterior solid part, bearing short but distinct recurved cusp at anterior edge of tooth, at point of fusión with accessory limb. Central formation well-developed, with rectangular or nearly square base and short, but robust, pointed central cusp.

Remarks: The genus was revised based on morphological grounds (Sysoev & Bouchet, 1996) and later with molecular data (Puillandre et ai, 2010). The molecular analysis (Zaharias et ai, 2024) revealed the presence of three still undescribed species. The type species of the genus, Gemmuloborsonia fierstinei, is conchologically similar to Recent species, and shares the characteristic gemmate subsutural cord. Some Gemmuloborsonia species strongly resemble species of Mcleanigemmula (see Remarks section under the latter genus).

Distribution: Broadly distributed in the Indo-Pacific, from Mozambique Channel and Madagascar in the West to Indonesia, the South China Sea, the Philippines, Papua New Guinea, the Solomon Islands, New Caledonia and the Tuamotus in the East; in 220 625 m.