Liotipoma mutabilis, Mclean, 2012

Mclean, James Hamilton, 2012, New species and genera of colloniids from Indo-Pacific coral reefs, with the definition of a new subfamily Liotipomatinae n. subfam. (Turbinoidea, Colloniidae), Zoosystema 34 (2), pp. 343-376 : 353-356

Liotipoma mutabilis n. sp.

( Figs 4 ; 5 )

TYPE MATERIAL. — Holotype: LIFOU 2000, stn 1435, Loyalty Islands, Lifou Island, Santal Bay , 20°55.2’S, 167°00.7’E, 5-30 m, diving team, 8.XI.2000, ♂ shell, H 3.4, D 5.7 mm ( MNHN 24757 , Fig. 4 A-D).

Paratypes: LIFOU 2000, stn 1436, Loyalty Islands, Lifou Island, Gaatcha Bay, Santal Bay , 20°55.5’N, 167°04.2’E, 10-20 m, diving team, 10.XI.2000, ♂ shell, H 3.0, D 5.1 mm ( MNHH 24758 , Fig. 4 E-H) ; ♀ shell, H 3.2, D 4.8 mm ( MNHN 24759 , Fig. 5 E-H). — LIFOU 2000, stn 1434, Loyalty Islands, Lifou Island, Huca Hutighé, Santal Bay , 20°52.5’S, 167°08.1’E, 5-20 m, diving team, 6.XI.2000, ♀ shell, H 2.7, D 4.2 mm ( MNHN 24760 , Fig. 5 A-D) .

TYPE LOCALITY. — Loyalty Islands, Lifou.

DISTRIBUTION. — Loyalty Islands, Lifou.

ETYMOLOGY. — Latin, changeable.

DESCRIPTION

Male shell ( Fig. 4 A-H)

Whorls 3.0; profile low for genus; peripheral keel at mid-whorl; profile below keel evenly rounded. Whorl expansion more than usual for genus, with strongly projecting peripheral angulation, shoulder ramp nearly flat above. Axial sculpture of strong ribs, 25-28 on last whorl; spinose and projecting in early whorls, spines projecting forward, spinosity and spacing of axial ribs much diminished in final third of last whorl. Spiral sculpture of three strong, low cords on shoulder in early whorls; changing to three narrow cords in final ⅓ whorl; base with strong subtending cord, and three cords of nearly equal strength between peripheral cord and subtending cord; base with deep pits on outer side of subtending cord and other basal cords. Umbilicus filled by emergent cord, bordered by subtending cord of nearly equal strength, both cords with lamellar extensions of axial sculpture; umbilicus partially open, partially obstructed by short, triangular tongue of inner lip in last half whorl; tongue aligned with aperture or slightly projecting forward, out of alignment with plane of aperture. Final lip massive, extending for ⅓ of final quarter whorl, showing about 20 successively decreasing layers of deposition, lip strongly showing spiral sculpture; tongue extending half the diameter of aperture on previous whorl, showing similar layers of deposition decreasing in extent. Plane of aperture coinciding with umbilical wall, plane of aperture coinciding with edge of tongue. H 3.0, D 5.1 mm (holotype).

Female shell ( Fig. 5 A-H)

Both specimens retain a portion of the tongue, but it both does not block the umbilical cavity. Two specimens ( Fig. 5 A-D, E-H) are considered to have been modified by the egg mass and the brooding of larvae to have increased the volume of the umbilical cavity. Both have the emergent cord excavated in a different manner: close to the aperture (tapered in A-D and truncate in E-H), and both have the subtending cord worn to not show the beaded intersection with the axial sculpture; the tongue is short in A-D and less shortened in E-H, but in both specimens the umbilical cavity is enlarged. H 2.7, D 4.2 mm ( Fig. 5 A-D); H 3.2, D 4.8 mm ( Fig. 5 E-H).

REMARKS

Liotipoma mutabilis n. sp. resembles L. splendida n. sp. ( Fig. 9 A-D), but has fewer axials (33 compared to 28) and a less expanding final whorl. It differs from L. dimorpha n. sp. in the thickness of the subtending cord and the basal cords, those of L. mutabilis n. sp. being thicker.

The operculum of L. mutabilis n. sp. ( Fig. 2G ) is known from a wedged-in juvenile specimen from the same station as that of the type material.The diameter of this operculum is 1.4 mm, which is larger than that of the two other known opercula ( L. wallisensis n. sp. and L. solaris n. sp.). It shows a very narrow central pit, which suggests that the pit might disappear altogether in larger specimens of this species.

This species is characterised by its greater expansion of the final whorl than usual for the genus, and its large size (D 5.9 mm), although it is smaller than L. magna n. sp. One other large species ( L. splendida n. sp.) reaches 5.1 mm in diameter.

There is a general resemblance to the species L. splendida n. sp. ( Fig. 9 A-D), but that species has a higher count of axial ribs (33 compared to 28) and has a tongue that extends forward to the plane of the aperture.

Figures

FIG. 4. — Liotipoma mutabilis n. sp., male shells: A-D, holotype (MNHN 24757, stn 1435), Pointe Lefèvre, Santal Bay, Lifou, Loyalty Islands, 5-30 m, H 3.4, D 5.7 mm; E-H, paratype (MNHN 24758, stn 1436), Gaatcha Bay, Santal Bay, Lifou, Loyalty Islands, 10-20 m, H 3.0, D 5.1 mm. Scale bars: 1 mm.

FIG. 5. — Liotipoma mutabilis n. sp., female shells: A-D, paratype (MNHN 24760, stn 1434), Santal Bay, Lifou, Loyalty Islands, H 2.7, D 4.2 mm;E-H, paratype (MNHN 24759,stn 1436),Gaatcha Bay,Santal Bay,Lifou,Loyalty Islands,H 3.2,D 4.8 mm. Scale bars:1 mm.

FIG. 9. — Liotipoma magna n. sp., female shells: A-D, paratype (MNHN 24768,stn DS105), off NW side Tutuba Island, Espiritu Santo, Vanuatu,92 m,H 3.6, D 5.7 mm;E-G, paratype,off W side Tutuba Island (MNHN 24769,stn DS105),off NW side Tutuba Island,Espiritu Santo, Vanuatu, 92 m, H 3.4, D 5.3 mm. Scale bars: 1 mm.

FIG. 2. — Opercula of three immature, sexually indeterminate species of Liotipoma McLean & Kiel, 2007; opercula wedged in place in all three specimens; A, B, L. wallisensis McLean & Kiel, 2007, off Wallis Island (MNHN, stn DW523), H 1.9, D 3.5 mm; C, D, inner and outer views of same operculum from immature specimen from Wallis Island, showing attached portion of columella, after breaking it free in order to show interior view; diameter of operculum 1.2 mm; E, F, L. solaris n. sp., Herald Pass, Great Astrolabe Reef, Fiji (LACM, stn 85-135), H 1.5, D 1.9 mm (SEM views of tilted specimen with operculum; apertural view is photo of coated specimen); G, Liotipoma sp., off Pointe Lefèvre, Santal Bay, Lifou, Loyalty Islands (MNHN, stn 1435), H 2.4, D 3.7 mm (specimen missing apical whorl). Scale bars: 1 mm.