Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 25t): GS9839B, Q10/f9531, near Oyster Point, Kaipara Harbour, Northland, Altonian (GNS)
Beu & Maxwell (1990): Chapter 11; p. 228; pl. 25 t.
Synonymy: Falsicolus gemmata Powell 1935b, p. 336; Falsicolus (sensu lato) gemmata, Beu & Maxwell 1990, p. 228, pl. 25t.
Type species of Gemmocolus Maxwell, 1992 (p. 125)
Description: Size moderate for genus (height 45-60 mm), fusiform, spire 0.4 total height. Protoconch not known, but probably conical, Of about 3 whorls as in other species. Teleoconch of 6 or 7 whorls, early whorls almost straight-sided, later whorls slightly concave on posterior half, gently convex below; last whorl with broadly convex periphery, shallowly excavated below with long, straight neck. Axial sculpture of low, narrow, rounded, prosocline costae reaching from suture to suture on spire, broadly curved on last whorl and extending across base, becoming obsolete near outer lip; 19-23 on penultimate whorl. Spiral sculpture of narrow, low cords, 4 or 5 on penultimate whorl and about 17 additional ones on last whorl, most with very fine interstitial threads. Spiral cords gemmate at intersections with axial costae. Aperture ovate, columella slightly concave above, twisted to left to form moderately long, straight siphonal canal. Inner lip moderately callused; outer lip slightly flexuous, lirate within.
Comparison: Gemmocolus gemmata is easily distinguished from most other species peviously referred to Falsicolus by its gemmate sculpture, the distinctive character of Gemmocolus Maxwell, 1992. A specimen from Sawyer's Creek, Boddytown, near Greymouth, Westland (Clifdenian) differs from the North Island shells mainly in having somewhat coarser nodules, and apparently represents an unnamed species (Maxwell 1992, p. 125). G. ectypa (Lillburnian, Gisborne district) which was originally assigned to Buccinulum (Ponder 1971b, p. 278) has more closely spaced costae and cords, and considerably coarser gemmules than G. gemmata. These are the only species of Gemmocolus known to date.
Distribution: Altonian; Motutara, West Auckland (type); Oyster Point, Kaipara Harbour.
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
(Included with a PDF facsimile file copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New Zealand)