Mipus alis, Oliverio, 2008

Oliverio, Marco, 2008, Coralliophilinae (Neogastropoda: Muricidae) from the southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 481-586 : 563-565

Mipus alis n. sp.

Figs 138, 139, 197

TYPE MATERIAL. — Holotype (dd) MNHN 20241 and 2 paratypes (dd) MNHN 20242-20243 .

TYPE LOCALITY. — Tonga, 23°23’S, 176°18’W, 407-443 m [BORDAU 2: stn DW 1631] .

MATERIAL EXAMINED. — New Caledonia proper. BATHUS 2: stn DW 731, Passe de Kouaré , 22°49’S, 166°45’E, 300-370 m, 1 dd .

Tonga. BORDAU 2: stn DW 1631, 23°23’S, 176°18’W, 407-

443 m, 2 dd (holotype MNHN 20241, Figs 138, 197 and paratype MNHN 20242); stn DW 1543, 21°16’S, 175°18’W, 427-436 m, 1 dd (paratype MNHN 20243, Fig. 139).

DISTRIBUTION. — Known only from the type locality ( Tonga) and New Caledonia, empty shells in 370-427 m.

DESCRIPTION — Shell of medium size for the genus, holotype height 16.8 mm, width 7.8 mm, of moderate thickness, turriculate, stepped below suture, whitish, aperture and parietal callus bright white.

Protoconch of 1.8 conical whorls, 520 Μm high, 710 Μm wide at base. Protoconch-I of about 0.8 whorls, entirely sculptured with pustules. Protoconch-II of about 1 whorl, with 2 spiral keels, sculptured with a series of subsutural prosocline threads, a series of tubercules over each keel, and a series of opisthocline threads between the second abapical keel and the suture.

Teleoconch of 6.3 whorls. Spire high, conical, constricted at base. Shoulder crest directed adapically. Subsutural ramp flat, narrow, whorls convex below keel. Aperture of medium size, 4.5 by 3 mm, subquadrangular. Outer lip incised corresponding to the shoulder keel. Inner lip curved, callous. Siphonal canal long (30% of total height), open, straight. Umbilicus closed with low siphonal fasciole. Teleoconch axial sculpture of 10 broad, rounded ribs on first whorls and 9 on last whorl, and of squamous growth lines over entire shell. Spiral sculpture of cords, covered with densely packed imbricate scaly spines. First spiral cord appearing on first teleoconch whorl becomes cord of shoulder keel, covered by imbricate scaly spines adapically directed. One additional cord adjoining below keel on each whorl, resulting in 6 spiral cords visible on penultimate whorl above aperture. Last whorl bearing 25 cords and 5 irregularly set cordlets. Suture not incised, undulate. Sutural ramp bearing 4 spiral cords on last whorl, commencing as 1 cord on second teleconch whorl.

Animal and operculum unknown.

REMARKS. — This new species is very similar to Mipus mamimarumai (Kosuge, 1981) . It differs in its marked shoulder keel and resulting sutural ramp, its axial sculpture and its straight siphonal canal. Mipus matsumotoi Kosuge, 1985 also lacks the axial ribs and the shoulder keel, resulting in a more slender shell. Mipus sugitanii Kosuge, 1985 has axial ribs and many specimens develop a keel (the corresponding spiral cord is the first one developing on the teleoconch, and therefore possiby homologous with the keel of M. alis ), but the whorls remain rounded, the sutural ramp is never flat, and the keel is not abapically oriented. Mipus intermedius Kosuge, 1985 and M. eugeniae (Bernardi, 1853) are larger and have more strongly convex whorls with the suture more incised. Mipus gyratus ( Hinds, 1844) and M. vicdani ( Kosuge, 1980) also develop a keel on the periphery, but are larger and the keel is not adapically oriented.

ETYMOLOGY. — The epithet alis refers to the R/V Alis, which was employed for the BORDAU 2 and BATHUS 2 expeditions in the southwest Pacific. It is used as a noun in apposition.