Hungerfordia pteropurpuroides K. Yamazaki and Ueshima, 2013

YAMAZAKI, KAZUNORI, YAMAZAKI, MIDORI & UESHIMA, REI, 2013, <p> <strong> Systematic review of diplommatinid land snails (Caenogastropoda, Diplommatinidae) endemic to the Palau Islands. (1) Generic classification and revision of <em> Hungerfordia </ em> </ strong> <br /> <strong> species with highly developed axial ribs </ strong> </ p>, Zootaxa 3743 (1), pp. 1-71 : 52-53

Hungerfordia pteropurpuroides K. Yamazaki and Ueshima sp. nov.

( Figs. 6C 1 , 9L , 24 , 29H )

Materials examined. Holotype. North-west of an unnamed peninsula locating south of Ngeream (Loc. BA 4-1), Airai state, Babeldaob island, Palau. Collected by R. U. and K. Y. on July 7, 2006. UMUTZ-MG-B0281 T.

Paratypes. Babeldaob and its satellite islet: Loc. BA4-1, 130 specimens, 7/VII/2006, UMUTZ-MG-B0281; Loc. BA4-2, 23 specimens, 7/VII/2006, UMUTZ-MG-B0295; Loc. BA4-4, 38 specimens, 8/VII/2006, UMUTZ-MG- B0306; Loc. BA5-2, 16 specimens, 12/XI/2006, UMUTZ-MG-B0447; Loc. BA5-3, 1 specimen, 12/XI/2006, UMUTZ-MG-B0464; Loc. BA6-3, 25 specimens, 21/X/2007, UMUTZ-MG-B0684; Loc. BA6-4, 46 specimens, 21/X/2007, UMUTZ-MG-B0688; Loc. BA7-3, 44 specimens, 2/II/2010, UMUTZ-MG-B1116; Loc. BA8-3, 85 specimens, 1/III/2011, UMUTZ-MG-B1311; Loc. BA8-4, 31 specimens, 1/III/2011, UMUTZ-MG-B1324; Loc. BA8-5, 42 specimens, 1/III/2011, UMUTZ-MG-B1334; Loc. BA8-1, 70 specimens, 1/III/2011, UMUTZ-MG- B1294

Diagnosis. Shell sinistral, large to very large for Hungerfordia species , slender conical. Shell color usually white, upper whorls frequently colored yellow or reddish brown. Constriction located above the aperture, followed by an axial protrusion of the shell wall, associated with abrupt reduction of the wing-like ribs. Apical septum present. Axial ribs on most whorls strongly developed as wings, very widely spaced, folded at the periphery on lower whorls; wing-like projections of the ribs very high, rather wide, arising at the suture on upper whorls; ribs above the aperture closely spaced, very low, without wing-like projections. Interspace between the wing-like ribs with characteristic growth wrinkles; growth wrinkles developed below the suture on the last 2 whorls, low, lamellar, becoming crowded and longer just behind the wing-like ribs. Spiral sculptures fine. Umbilicus closed or narrowly opened. Axial protrusions of shell wall (along the ribs) strongly developed on the last 3/4 whorls. Aperture hardly tilted. Columellar tooth very weak or reduced. Peristome double; outer peristome widely expanded beyond the inner one, upper columellar margin strongly reflected backward, with concentric growth wrinkles on the inner surface; inner peristome also expanded, parietal margin located near or below the middle level of the upper body whorl. Interspace between the inner and outer peristomes rather narrow.

Description. Shell ( Figs. 6C 1 , 24A–L , 29H ). Shell sinistral, large to very large for Hungerfordia species , slender conical, last whorl widest when removing the protruded ribs and peristomes. Shell color usually white, rarely faint reddish brown, upper whorls frequently yellow or reddish brown colored with the color becoming deeper toward the apical septum (apical whorls above the septum always uncolored). Whorls 6.5–8, slightly convex; last 1/16–1/8 whorls (including interspace between the outer and inner peristomes) expanded upward and ascending onto the penultimate whorl in left lateral view. Suture impressed. Constriction located above the parietal/ columellar junction of the aperture, associated with abrupt reduction of wing-like ribs, followed by a strong axial protrusion of shell wall, internally without palatal plica except for a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1+1/8–1.5 whorls, very weakly and finely punctated below the suture and on the lower whorl. Apical septum present, constructed inside at 1–2 whorls after the protoconch/teleoconch junction. Axial ribs developed on the teleoconch, oblique to the coiling axis, strongly developed as wings on most whorls: ribs undeveloped on the initial 1/4 whorls of the teleoconch; ribs on the following 1/3–1/4 whorls of initial teleoconch low, moderately to widely spaced, not folded; ribs on the subsequent whorls (except above the aperture) very highly and widely protruded as wings, very widely spaced (9–11 ribs in a whorl), not synchronized with those on the previous whorls, not folded on the upper whorls, gradually becoming folded at the periphery on the last 1.5– 3 whorls; upper margin of the ribs above the wing-like projection (between the suture and wing) on the last 2 whorls low, indistinct or slightly elevated; wing-like projections of the ribs very high, wide, weakly pointed at the shoulder, slightly curved upward, arising at the suture on upper whorls, becoming to arising at some distance below the suture (near periphery of a whorl) on the last 2 whorls, upper margin weakly folded at the periphery over the lower margin on lower whorls, lower margin extended below to the suture of the next whorl, protruded rather upward on most whorls, becoming protruded laterally to rather downward on the last 3/4 whorls, with fine spiral sculptures on the outer surface; ribs above the aperture (ribs on the last 1+1/8 to last 3/4 whorls around the constriction) abruptly becoming closely spaced and very low, without wing-like projection, hardly folded at the periphery, frequently almost smooth below the periphery, occasionally with 1–3 faint growth wrinkles between them. Interspace between the wing-like ribs smooth on upper whorls, with characteristic growth wrinkles on lower whorls. Growth wrinkles developed below the suture on the last 2 whorls, low, lamellar, short and moderately spaced soon after the wing-like ribs; becoming longer, higher, and abruptly crowded just behind the wing-like ribs; visible as white and fine wrinkles in apical view. Spiral sculptures present throughout the teleoconch, fine, weak, extending on outer surface of the wing-like ribs and outer peristome, sinuous in high magnification. Base convex, without basal keel. Axial protrusions of shell wall (along the ribs) strongly and rather sharply developed on the last 3/4 whorls, hidden by the wing-like ribs in fresh specimens, abapertural side narrow and rather steep, adapertural side rather convex and much wider than the abapertural side in umbilical view. Umbilicus closed or very narrowly opened, visible in oblique umbilical view. Aperture hardly tilted downward against the coiling axis, hardly or slightly protruded; columellar axis within aperture almost vertical or slightly oblique. Columellar tooth reduced or very weakly developed, very low and recessed deeply inside the aperture when present. Peristome double, widely expanded; outer peristome widely expanded beyond the inner one at the palatal and basal sides, with rounded palatal and baso-columellar edges, reflected backward at the upper columellar margin, prominently folded just below the suture (at the upper palatal margin) in left lateral view, with concentric grow wrinkles on the inner surface, with fine spiral sculptures on the outer surface; inner peristome pentagonal circular, expanded all around, hardly reflected, shortly protruded from the outer one, parietal margin located below the middle level of the upper body whorl. Interspace between the inner and outer peristomes rather narrow or moderately wide, with some growth lines or very low growth wrinkles on the outer surface, weakly constricted at the basal and palatal sides; uppermost margin ascending onto the penultimate whorl toward the aperture in left lateral view.

Dimensions. Shell height 5.1–6.5 mm, diameter 3.4–5.1 mm, suture width 2.1–2.5 mm, peristome height 1.8– 2.3 mm.

Operculum ( Figs. 24M 1 –M 4 ). Operculum corneous, multispiral, circular, transparent, amber colored, thin, flat, slightly concave; outer surface smooth; inner surface with a low, weak, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula ( Fig. 9L ). Radula of specialized type of taenioglossate; ribbon very long. Central tooth very large, with a very wide, large, and blunt central cusp, with or without a pair of vestigial lateral cups, basal plate longitudinally elongated and strongly constricted at the base. Lateral teeth also large, with a large, very wide and blunt major cusp, with or without a vestigial inner cusp, without outer cusp, basal plate obliquely elongated. Inner marginal teeth shorter than the lateral teeth, elongated, with a large and wide major cusp, with one or two slender inner cusp(s) and a small outer cup. Outer marginal teeth shorter than the inner marginal, with a large, wide and blunt major cusp, with two slender inner cusps, without outer cusp.

Distribution and ecology. Endemic to Palau: Babeldaob island (southern coastal limestone area) and its satellite islets. The species inhabits vertical walls of large limestone rocks or on limestone rubbles.

Remarks. H. pteropurpuroides is similar to H. subalata , H. lamellata , and H. alata . The latter two species occur sympatrically with this species. H. pteropurpuroides differs from H. lamellata by the presence of an apical septum, the absence of axial palatal plica inside the constriction, and the absence of an abrupt whorl swelling after the constriction. H. pteropurpuroides also differs from H. subalata by the presence of an apical septum, the absence of short growth wrinkles above the suture of the last 2 whorls, the inner peristome being not tilted downward, and lacking of wing-like projections of the ribs above the aperture. H. pteropurpuroides is distinguished from H. alata by its smaller shell, the less expanded and less reflected peristomes, the less protruded aperture, the presence of concentric growth wrinkles on the inner surface of the outer peristome, and the narrower interspace between the inner and outer peristomes. H. pteropurpuroides is also characteristic in that the lamellar growth wrinkles are developed just behind the wing-like ribs on the penultimate whorl. Such growth wrinkles are also present below the suture in other species, but are much lower or undeveloped on the penultimate whorl.

Etymology. The specific name, derived from a marine gastropod genus Pteropurpura (Family Muricidae ), refers to the Pteropurpura –like shell with strong wing-like ribs.

Figures

FIGURE 1. Map of Palau islands showing collecting sites. Small red circles show collecting sites. Areas encircled by blue rectangles are shown as enlarged maps in Figs. 2–5. Abbreviations of the collecting sites are listed in Table 2.

FIGURE 6. Terminology used in this study. (A) Shell dimensions. Abbreviations: D, shell diameter; H, shell height; PH, peristome height; SW, suture width. (B) An example showing the axial protrusions of shell wall along the axial ribs. Umbilical view of a shell of Hungerfordia pyramis (Crosse, 1866), only the last whorl shown. (C) Apical septa of some Hungerfordia species: (C1) apical whorls of a shell (live condition) of H. pteropurpuroides sp. nov.; (C2) apical whorls of a partially opened shell of H. alata (Crosse, 1866), which shows construction of an internal septum; (C3) subapical view of a shell of H. triplochilus sp. nov. after removal of the empty apical whorls above the septum.

FIGURE 9. Radulae of Hungerfordia species. (A) H. pelewensis Beddome, 1889, B0283; (B) H. triplochilus sp. nov., topotypic paratype, B0158; (C) H. expansilabris sp. nov., topotypic paratype, B1299; (D) H. nudicollum sp. nov., topotypic paratype, B0364; (E) H. echinata echinata sp. et subsp. nov., paratype, B1084; (F) H. echinata tubulispina subsp. nov., topotypic paratype, B0169; (G) H. elegantissima sp. nov., topotypic paratype, B0375; (H) H. goniobasis goniobasis sp. et subsp. nov., topotypic paratype, B0235; (I) H. goniobasis dmasechensis subsp. nov., topotypic paratype, B0579; (J) H. lamellata (Crosse, 1866), B0157; (K) H. subalata sp. nov., paratype, B0021; (L) H. pteropurpuroides sp. nov., topotypic paratype, B1116; (M) H. alata (Crosse, 1866), B1041; (N) H. papilio papilio sp. et subsp. nov., paratype, B0374; (O) H. papilio stenoptera subsp. nov., paratype, B0761. Scale bars, 10 µm. All specimens, UMUTZ-MG.

FIGURE 24. Hungerfordia pteropurpuroides sp. nov. (A1–A4) A topotypic paratype, B0281a; (B) columella (left lateral view), (C) axial ribs above the aperture, (D) apical septum, and (E) sculpture on the penultimate whorl of topotypic paratypes (B0281a–d); (F1) left lateral view, and (F2) oblique apical view of sculpture on the penultimate whorl of the holotype; (G) umbilical view of a topotypic paratype after removal of the winged ribs, only the last whorl shown, B0281e; (H) oblique umbilical view of a paratype from Loc. BA8-3, a specimen with a narrowly opened umbilicus, B1311; (I1–I4) holotype, B0281T; (J) a paratype from Loc. BA5-2, B0447; (K) a paratype from Loc. BA6-3, B0684; (L) a paratype from Loc. BA4-2, B0295; (M1, M2) outer surface, and (M3, M4) inner surface of operculum, a topotypic paratype, B0281. Scale bars, 1mm (A–L), 0.5 mm (M). All specimens, UMUTZ-MG.

FIGURE 29. Shell size and shape variation among Hungerfordia species with highly developed ribs. (A) H. triplochilus sp. nov., holotype; (B) H. expansilabris sp. nov., holotype; (C) H. nudicollum sp. nov., holotype; (D) H. echinata echinata sp. et subsp. nov., holotype; (E) H. echinata tubulispina subsp. nov., holotype; (F1) H. lamellata (Crosse, 1866), B0199a; (F2) H. lamellata (Crosse, 1866), B0282b; (G) H. alata (Crosse, 1866), B0446; (H) H. pteropurpuroides sp. nov., holotype; (I1) H. subalata sp. nov., paratype (B0655); (I2) H. subalata sp. nov., holotype; (J) H. papilio stenoptera subsp. nov., holotype; (K) H. papilio papilio sp. et subsp. nov., holotype; (L) H. goniobasis dmasechensis subsp. nov., holotype; (M) H. goniobasis goniobasis sp. et subsp. nov., holotype; (N) H. elegantissima sp. nov., holotype; (O1) H. pelewensis Beddome, 1889, B0542; (O2) H. pelewensis Beddome, 1889, B0383. Scale bar, 1mm. All specimens, UMUTZ-MG.

FIGURES 4–5. Enlarged maps of Palau islands showing collecting sites. Top (Fig. 4), map of Ngerkutabel island and its neighboring islands or islets; bottom (Fig. 5), map of Mecherchar island and its neighboring islands or islets. Abbreviations of the collecting sites are listed in Table 2.