Hungerfordia globosa M. Yamazaki and Ueshima

Yamazaki, Midori, Yamazaki, Kazunori, Rundell, J. & Ueshima, Rei, 2015, Systematic review of diplommatinid land snails (Caenogastropoda, Diplommatinidae) endemic to the Palau Islands. (3) Description of eight new species and two new subspecies of Hungerfordia, Zootaxa 4057 (4), pp. 511-538 : 534-536

Hungerfordia globosa M. Yamazaki and Ueshima sp. nov.

(Figs. 11, 12A)

Materials examined. Holotype. Northern part of Ngermalk island (Loc. Nm5-1), Palau. Collected by R. U. on Nov. 13, 2006. UMUTZ-MG-B0521T. Paratype. Ngermalk: same data as holotype, 1 specimen, UMUTZ-MG- B0521.

Diagnosis. Shell sinistral, very small for Hungerfordia species, subspherical. Shell color transparant, glossy. Axial ribs partially present on teleoconch; ribs on the apical 3 whorls present, closely spaced, low but distinct; ribs on the last 2–1+3/4 whorls absent, but reappearing just behind the thickened lip. Spiral sculpture very weakly developed only on the apical whorls, absent on most whorls. Dorsal grooves weakly developed on the last 3/4 whorls, axial, 4–5, widely spaced, shallow; interspace between the dorsal grooves wide, convex. Base convex, with a circum-columellar fold; circum-columellar fold prominently developed on the last 3/4 whorls, extended along the columellar side of the thickened lip, narrow, with fine growth lines on its suface. Outer peristome hardly developed. Inner peristome subcircular. Parietal tooth absent. Columellar tooth rather strongly developed. Thickened lip strongly developed behind the aperture, wide, gradually narrowed toward the aperture at the palatal and basal sides; dorsal margin distinct, abruptly expanded from the preceding whorl.

FIGURE 11. Hungerfordia globosa sp. nov. (A1–7, B1–6) holotype, B0521T; (C) a topotypic paratype, Loc. Nm5-1, B0521. Scale bars, 1mm. All specimens, UMUTZ-MG.

Description. Shell (Figs. 11A–C, 12A). Shell sinistral, thick, very small for Hungerfordia species, subspherical, penultimate whorl widest when excluding the thickened lip; sides well convex (particulary on the last 3 whorls). Shell color transparant, rather glossy. Whorls 5–5+1/4, convex, broadest (in longitudinal width) on the penultimate whorls in dorsal view; last 3/4 whorls with axial dorsal grooves, with a circum-columellar fold; last 1/ 8 whorls (including the thickened lip) expanded upward, ascending onto the penultimate whorl in left lateral view. Suture impressed. Constriction located above the parietal/columellar junction of the aperture, less prominent in external view. Tuba 7/8 whorls. Protoconch 1–1+1/8 whorls, almost smooth, finely and very weakly punctated on lower whorl. Apical septum absent. Axial ribs poorly developed on teleoconch, partially disappearing, almost straight (never folded at the peripheries of the whorls), oblique to the coiling axis: ribs on apical 3–3+1/8 whorls of teleoconch present, closely spaced (14–17 ribs in a quarter whorl), weak but distinct, very low, becoming weaker on the penultimate whorl; ribs on the last 2–1+3/4 whorls disappearing, completely absent or reduced to faint growth lines, but reappearing just behind the thickened lip (very fine and somewhat distorted by dorsal grooves). Spiral sculpture hardly deveoloped on teleoconch, absent throughout whorls, or very weakly developed only only on the apical 2.5 whorls of teleoconch, very weak and fine when present, sinuous in high magnification, always absent on the last 2.5 whorls. Dorsal grooves developed on the last 3/4 whorls, axial, 4–5, moderately impressed, widely spaced, arising at a short distance below the suture, disappearing at the base above the cirum-columellar fold: interspace between the axial grooves wide, well convex. Base convex, with a prominent circum-columellar fold; circum-columellar fold developed on the last 7/8 whorls, delimitted by a prominent subspiral groove, initially developed along the columellar side of the thickened lip and almost radially straight in umbilical view, then winding around the columella just behind the thickened lip, with a series of fine and short growth wrinkles around the columella. Umbilicus closed in adult. Aperture hardly protruded, slightly tilted downward against the coiling axis in left lateral view; columellar axis within aperture somewhat tilted outward in front view. Columellar tooth rather strongly developed, emerged at the aperture, but never extended onto the inner peristome, deeply extended inward about 3/4 whorls. Parietal tooth absent within the aperture. Peristome single. Outer peristome undeveloped. Inner peristome subcircular of squarish circular, moderately expanded in all around; parietal margin located near or below the middle level of the upper body whorl. Thickened lip strongly developed behind the aperture, wide, expanded beyond the inner peristome in front view, white, lacking of periostracum, with fine growth lines on its outer surface, gradually narrowed toward the aperture (in particulr, at the palatal and basal sides), slightly constricted just behind the inner peristome; dorsal margin rather distinct, abruptly expanded from the preceding whorl at the palatal side; uppermost margin (= suture) ascending onto the penultimate whorl toward the aperture in left lateral view; base also ascending toward the aperture in left lateral view; palatal margin protruded beyond the penultimate whorl in apical view.

Dimensions. Shell height 2.6–2.7 mm, shell diameter 1.8–1.9 mm, suture width 1.6 mm, peristome height 1.0 mm.

Operculum. Not examined.

Penis. Not examined.

Radula . Not examined.

Distribution and ecology. Endemic to Palau: Known only from the type locality of Ngermalk island. The species inhabits limestone rocks.

Remarks. H. globosa is most similar to H. lutea hemilaevis Yamazaki & Ueshima, 2015 in having smooth penultimate whorl without axial ribs, but differs from the latter by the more spherical shell shape, the presence of axial dorsal grooves on the last 3/4 whorls, the absence of axial ribs above the aperture, and the dorsal margin of the thickened lip being abruptly expanded from the preceding whorl (Figs. 12A, B).

H. globosa is also similar to H. crassilabris crassilabris ( Crosse, 1866) , but distinguished from the latter in the following points: the shell shape is more spherical; the axial ribs are almost absent on the last 2 whorls; parietal tooth is never developed within the aperture; the dorsal grooves are not so deeply impressed, but occur in higher number (4–5); the spiral sculpture is absent on the lower whorls (Figs. 12A, C).