Original Description of Gladius (Rostellaria) melanocheilus by Adams, 1854, p. 42:
- "G. testa fusiformi-turrita, pallide castanea; anfractibus convexiusculis, laevibus, supremis longitudinaliter costatis, ultimo gibboso, antice transversim sulcato; labio antice incrassato, reflexo; labro margine dentato, fusco-nigrscente; rostro praelongo, recto.
Locus typicus: "Eastern Seas" (Adams, 1854)
History and Synonymy
Rostellaria fusus in Reeve, 1851, Rostellaria, pl. 2, fig. 5 a, b
Specimens from private collections
Tibia melanocheilus (Adams, 1854); Gulf of Bengal, West of Thailand; from fish trawler, at 60-80 m; 153 mm; Coll. Christian B÷rnke
Tibia melanocheilus (Adams, 1854); Raja Island (Pulau Raja), northeast of Sumatra Island, Indonesia; Trawled by Thai trawlers, -80~120m; 127.2mm; Coll. Chong Chen
- The "Dark-Mouthed Tibia" is a peculiar rostellariid strongly resembling its sister species Tibia fusus (L., 1758) but has a dark brown aperture and yellowish brown parietal callus as opposed to white in T. fusus. The shell is also usually more compressed and squat, and the siphonal canal is also shorter than T. fusus. For some time it was treated as a subspecies of T. fusus, but now usualy accepted as a separate full species based on these differences. It lives burrowed in sand of shallow to moderate depths around -20~150m, and is quite uncommon especially live-taken specimens in good condition. The distribution range is supposed to be from Sabah, Malaysia to as far as Bangladesh, but vast majority of specimens originate from around northwest Sumatra, Indonesia. Although the exact feeding habits of Tibia species is unclear, they are presumed to be herbivorous to omnivorous gastropods which swallow quantities of sand and digest algae and detritus within, as well as grazing on algae. Typical shell length around 130mm, very large specimens may exceed 165mm.
Tibia melanocheilus (Adams, 1854); Trawled by Thai fishing boats near NW Sumatra Island, Indonesia; 180 mm; 2002; Coll. RenÚ Vanwalleghem
Tibia melanocheilus (Adams, 1854); Brunei; 121 mm; Coll. Ricardo Villar
Specimens from institutional collections
Tibia melanocheilos (Adams, 1854); Pliocene/Pleistocene; Coll. Naturalis; Copyright Naturalis