Hungerfordia brachyptera 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 : 523-525

Hungerfordia brachyptera M. Yamazaki and Ueshima sp. nov.

(Figs. 6, 12Q)

Materials examined. Holotype. 600m North of Metkerel a Chudel (Loc. Mc6-3), northeastern part of Mecherchar island, Palau. Collected by R. U. on Oct. 25, 2007. UMUTZ-MG-B0842T. Paratypes. Mecherchar: same data as holotype, 2 specimens, UMUTZ-MG-B0842.

Diagnosis. Shell sinistral, slender conical, large to very large for Hungerfordia species. Shell color white or transparent, upper whorls yellow colored. Apical septum present. Axial ribs on most whorls, strongly developed, highly protruded as wings, very widely spaced, elevated by axial protrusions of shell wall; wing-like projections of the ribs wide, rather short for winged Hungerfordia species, hardly or very weakly folded at the peripheries of whorls; ribs above the aperture closely spaced, very low, without wing-like projections; ribs on the last 3/4 whorls very widely spaced (with the interspace much wider than those on the upper whorls), with strong wing-like projections, very strongly elevated by axial protrusions of shell wall along the ribs. Interspace between the winged ribs with fine growth wrinkles below the suture. Spiral sculpture present throughout teleoconch whorls. Basal keel developed on the penultimate and the higher 1–2 whorls, a trace of angulate base in younger stage, obviously visible just above the suture of the last whorl, but disappearing on the last whorl itself. Aperture slightly protruded, weakly tilted downward in left lateral view. Columellar tooth very weak. Peristome double. Outer peristome strongly developed, widely expanded beyond the inner peristome, with a rounded baso-columellar edge. Inner peristome moderately expanded; parietal margin located below the middle level of the upper body whorl. Interspace between the outer and inner peristomes wide, rather smooth on the outer surface.

Description. Shell (Figs. 6A–D, 12Q). Shell sinistral, large to very large for Hungerfordia species, slender conical, last whorl widest when removing the protruded ribs and peristomes. Shell color white or transparent, upper whorls occasionally yellow with the color becoming deeper towards the apical septum, apical whorls above the apical septum always uncolored. Whorls 7–8, convex; last 1/8 whorls (including interspace between the outer and inner peristomes) expanded upward, ascending onto the penultimate whorl in left lateral view. Suture impressed; suture on the last 1–3/4 to last 1/3 whorls deeply impressed, running slightly inside the basal keel of the penultimate whorl. Constriction located above the parietal/columellar junction of the aperture, associated with abrupt changes of the ribbing pattern, internally without palatal plica except a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1+1/3 whorls, almost smooth, lower whorl faintly and very finely punctated. Apical septum present, constructed inside the apical whorls, constructed at 0.5–1+1/3 whorls after the protoconch/teleoconch boundary. Axial ribs developed on the teleoconch, oblique to the coiling axis, strongly protruded as wings on most whorls; ribs on the first 1/4–1/3 whorls of the initial teleoconch closely spaced, low, almost straight (not folded at the peripheries of the whorls); ribs on the subsequent whorls higher than the last whorl (ribs on most whorls) strongly protruded as “wings”, very widely spaced (8–10 ribs in a whorl), not synchronized with those on the previous whorls, hardly or weakly folded at the peripheries of the whorls, strongly elevated by axial protrusions of shell wall along the ribs; wing-like projections of the ribs strongly developed, but rather short for winged Hungerfordia species, rather wide, obtusely pointed at the shoulder, weakly curved upward, arising at the suture on upper whorls, becoming to be arising at some distance below the suture on the lower whorls, protruded rather upward, lower margin extended below to the suture of the next whorl, with fine spiral sculptures on the outer surface; ribs above the aperture (ribs on the last 1 to last 3/4 whorls around the constriction) abruptly changed, closely spaced, very low, without any wing-like projections, not folded; ribs on the last 3/4 whorls strongly developed as “wings” again, very widely spaced, with the interval much wider than those on the upper whorls (2 ribs in a quarter whorl), very highly elevated by axial protrusions of shell wall along the ribs (particularly at the first winged rib which reappears after the constriction, and the second rib located at right side of the aperture); wing-like projection of the ribs strongly developed and shaped as those on the upper whorls, protruded laterally or rather downward, arising at or near the suture. Interspace between the wing-like ribs with fine growth wrinkles below the suture, which are occasionally extended below to the suture of the next whorl. Spiral sculptures present throughout teleoconch whorls, fine, rather prominent, extended onto outer surface of the winglike ribs and outer peristome, sinuous in high magnification. Basal keel developed on the penultimate and the higher 1–2 whorls, a trace of angulate base in younger stages, recognizable just above the suture of the last 2–3 whorls in adult shell, most obvious just above the suture of the last whorl in oblique umbilical view, but disappearing on the last whorl itself. Base not convex, rather rugged by the strong axial protrusions of shell wall FIGURE 6. Hungerfordia brachyptera sp. nov. (A1–9, D) A topotypic paratype, Loc. Mc6-3, B0842a: (A8) sculptures on the penultimate whorl, left lateral view, showing that the basal keel of the penultimate whorl (indicated by arrowheads) is developed just above the suture of the last whorl: (A9) oblique umbilical view, note that the suture of the last whorl is running slightly inside the basal keel of the penultimate whorl (indicated by arrowheads), note also that the axial protrusions of shell wall are strongly developed along the ribs on the last 3/4 whorls; (B1–5) holotype, B0842T; (C1–2) a topotypic paratype, B0842b: (C2) umbilical view, only the last whorl shown, note the strongly developed axial protrusions of shell wall along the ribs; (E1–2) outer surface, and (E3–4) inner surface of operculum, topotypic paratype, B0842a. Arrowheads indicate the basal keel of the penultimate whorl. Scale bars, 1mm. All specimens, UMUTZ-MG.

along the ribs. Umbilicus closed in adult. Axial protrusions of shell wall (along the wing-like ribs) on the last 3/4 whorls very strongly developed, in particular, highly developed at a strong rib just after the constriction and the next rib protruded toward the right lateral side of the aperture; abapertural side concave in umbilical view; adapertural side concave or only slightly convex in umbilical view, almost similarly wide as the abapertural side. Aperture weakly protruded (at the parietal side), tilted downward against the coiling axis in left lateral view; columellar axis within aperture slightly oblique to the coiling axis. Columellar tooth very weak, very low, recessed deeply inside the aperture. Peristome double. Outer peristome strongly developed, very widely expanded beyond the inner peristome in front view, abruptly reduced at the lower columellar side to form a rounded baso-columellar edge, with fine concentric growth lines on the inner surface, with fine spiral sculptures on the outer surface. Inner peristome squarish circular, rather widely expanded in all around, weakly protruded from the previous whorl at the parietal side, strongly protruded from the outer peristome, parietal margin located below the middle level of the upper body whorl. Interspace between the inner and outer peristomes wide, widest at the upper palatal side and narrowed toward the base in left lateral view, almost smooth and with fine growth lines on the outer surface; uppermost margin (= suture) ascending onto the penultimate whorl toward the aperture in left lateral view.

Dimensions. Shell height 5.9–6.3 mm, diameter 3.3–3.6 mm, suture width 2.2–2.3 mm, peristome height 1.8– 2.0 mm.

Operculum (Figs. 6E1–4). Operculum corneous, multispiral, circular, thin, transparent, amber colored, slightly concave; outer surface smooth; inner surface with a low, thin, weak, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula . Not examined.

Distribution and ecology. Endemic to Palau: Mecherchar island. The species inhabits vertical walls of large limestone rocks, and limestone rubble.

Remarks. H. brachyptera is distinguished from other winged Hungerfordia species in the following points: the characteristic basal keel is developed on the penultimate whorls and the higher 1–2 whorls (most prominent just below the suture of the last whorl); the wing-like ribs are shorter, less folded; the ribs on the last 3/4 whorls are very widely spaced, very strongly elevated by axial protrusions of shell wall along the ribs; the ribs above the aperture are closely spaced, very low, and without any wing-like projections; the inner peristome is not so widely expanded; apical septum is present.

Etymology. The specific name, derived from Latinized Greek brachys and pterus, refers to the wing-like ribs that are rather short for winged Hungerfordia species.