Hungerfordia alata ( Crosse, 1866 ) YAMAZAKI & YAMAZAKI & 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 : 55-58

Hungerfordia alata ( Crosse, 1866) comb. nov.

( Figs. 6C 2 , 9M , 10H , 11J , 25 , 26 , 29G )

Palaina alata: Semper, 1865 , name only (nom. nud.), p. 292.

Palaina alata: Crosse, 1866, p. 348 , pl. X, fig.1.

Diplommatina alata: Pfeiffer, 1876a, p. 18 .

Diplommatina (Palaina) alata: Pfeiffer, 1876b, pp. 397–398 .

Palaina (Palaina) alata: Kobelt & Moellendorff, 1898, p. 131 .

Palaina alata: Kobelt, 1902, p. 394 .

Materials examined. Syntype. Nermaleh, single specimen, MNHN 26601 (Muséum National d’Histoire Naturelle, Paris) . Additional materials. Babeldaob: Loc. BA 5-2, 18 specimens, 12/XI/2006, UMUTZ-MG-B0446. Koror and its satellite islet: Loc. Ko2-2, 112 specimens, 7/XI/2004, UMUTZ-MG-B0058; Loc. Ko6-1, 22 specimens, 21/X/2007, UMUTZ-MG-B0700; Loc. Ko5-6, 2 specimens, 14/VII/2006, UMUTZ-MG-B0393. Ulebsechel: Loc. Ub6-1, 16 specimens, 22/X/2007, UMUTZ-MG-B0749; Loc. Ub7-1, 26 specimens, 31/I/2010, UMUTZ-MG- B1041; Loc. Ub7-2, 21 specimens, 31/I/2010, UMUTZ-MG-B1062; Loc. Ub7-3, 1 specimen, 31/I/2010, UMUTZ- MG-B1071; Loc. Ub7-4, 24 specimens, 31/I/2010, UMUTZ-MG-B1083; Loc. Ub8-1, 55 specimens, 3/III/2011, UMUTZ-MG-B1429. Ngerchaol: Loc. Ch5-1, 26 specimens, 14/XI/2006, UMUTZ-MG-B0523; Loc. Ch6-1, 37 specimens, 22/X/2007, UMUTZ-MG-B0709; Loc. Ch8-2, 34 specimens, 3/III/2011, UMUTZ-MG-B1396 .

Diagnosis. Shell sinistral, very large for spiny Hungerfordia species , slender conical. Shell color usually white, upper whorls occasionally yellow or reddish brown. Constriction located above the aperture, associated with abrupt reduction of the wing-like ribs. Apical septum present. Axial ribs on most whorls strongly protruded as wings, very widely spaced, folded at the periphery; wing-like projection on the ribs very high, wide, arising at the suture on upper whorls; ribs above the aperture very closely spaced, very low, almost without wing-like projections. Spiral sculptures fine. Aperture strongly protruded, hardly tilted. Columellar tooth very weakly developed deeply inside the aperture. Peristome double, very wide; outer peristome very widely expanded beyond the inner one at the palatal and basal sides, reflected backward, with rounded palatal and baso-columellar edges, upper columellar margin strongly folded backward; inner peristome circular, very widely expanded all around (particularly at the parietal side), strongly reflected, thickened, parietal margin located near or slightly expanded beyond the middle level of the upper body whorl. Interspace between the inner and outer peristomes wide, with a series of fine and very low riblets on the outer surface.

Description. Shell ( Figs. 6C 2 , 11J , 25A–K , 26A 1 –A 4 , 26C , 29G ). Shell sinistral, very large for Hungerfordia species , slender conical, last whorl widest when removing the expanded ribs and peristomes. Shell color usually white, upper whorls occasionally yellow or reddish brown with the color becoming deeper towards the apical septum (apical few whorls above the apical septum always uncolored), last 3/4 whorls rarely colored faint orange or yellow in some exceptional populations. Whorls 6–7.5, convex; last 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 axial ribs, internally without palatal plica except a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1.25–2 whorls, apical whorl rather smooth, lower whorl finely and faintly punctated. Apical septum present, constructed inside at 0.5–2 whorls after the protoconch/teleoconch junction. Axial ribs developed on the teleoconch, oblique to the coiling axis, highly developed and protruded as wings on most whorls: ribs on first 1/3–1/2 whorls of the teleoconch low, not folded, closely to widely spaced, occasionally undeveloped on the initial 1/4 whorls; ribs on the subsequent whorls (except above the aperture) highly and widely protruded as wings, very widely spaced (7–10 ribs in a whorl), not synchronized with those on the previous whorls, folded at the periphery; upper margin of the ribs above the wing-like projection (between the suture and wing) on the last 1–1.5 whorls low, indistinct or slightly elevated; wing-like projections of the ribs very high, wide, weakly pointed at the shoulder, curved upward, weakly reflected backward, weakly folded at the periphery, arising at the suture on upper whorls, becoming to arising at some distance below suture (near periphery of a whorl) on the last 1–1.5 whorls, upper margin weakly folded over the lower margin, lower margin very widely expanded 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 3/4 whorls around the constriction) abruptly becoming very closely spaced and very low, almost without wing-like projections, becoming less folded at periphery toward the constriction. Interspace between the wing-like ribs smooth on the upper whorls, with growth wrinkles on the lower whorls; upper growth wrinkles present below the suture on the last 1.5 whorls, fine, low; lower growth wrinkles occasionally present above suture on the last 1.5 whorls, very weak. Spiral sculptures present throughout the teleoconch, fine, 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 wing-like ribs) developed on the last 3/4 whorls, hidden by the wing-like ribs; abapertural side narrow; adapertural side convex and much wider than the abapertural side in umbilical view. Umbilicus closed in adult, covered by columellar reflection of outer peristome. Aperture strongly protruded, hardly tilted downward against the coiling axis; columellar axis within aperture almost vertical. Columellar tooth very weakly developed, recessed deeply within the aperture (hardly visible in front view), very low, reducing toward aperture. Peristome double, very widely expanded: outer peristome very widely expanded beyond the inner one at the palatal and basal sides, reflected backward, abruptly narrowed towards the angular edge, with rounded palatal and baso-columellar edges, upper columellar margin distinctly folded backward and covering basal wall near the columella, smooth and polished on the inner surface; inner peristome circular, very widely expanded all around, strongly reflected backward, thickened, strongly protruded from the outer one, parietal margin located near or slightly expanded beyond the middle level of the upper body whorl. Interspace between the inner and outer peristomes usually wide (rarely narrow), with a series of fine, very low riblets on the outer surface; uppermost margin ascending onto the penultimate whorl toward the aperture in left lateral view; base extended almost horizontally in left lateral view.

Dimensions. Shell height 6.7–8.3 mm, diameter 4.5–6.1 mm, suture width 2.1–3.0 mm, peristome height 2.0– 3.0 mm.

Operculum ( Figs. 10H , 25L 1 –L 4 ). Operculum corneous, multispiral, circular, transparent, amber colored, thin, flat, slightly concave: outer surface smooth; inner surface with a low, thin, weak, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula ( Fig. 9M ). 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 near the base. Lateral teeth also large, with a large, very wide and blunt major cusp, without inner nor outer cusp, basal plate obliquely elongated. Inner marginal teeth with a large and wide major cusp, with two slender inner cusps, with a small outer cup. Outer marginal teeth shorter than 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 (southern coastal limestone area), Koror (eastern limestone area), Ulebsechel, Ngerchaol islands and their satellite islets. The species inhabits vertical walls of large limestone rocks or cliffs, occasionally on limestone rubbles.

Remarks. Among the Palauan diplommatinids hitherto described, “ Palaina ” alata Crosse, 1866 is the only species that has highly developed and wing-like axial ribs. We found that at least five large-sized Hungerfordia species match the original description of “ P.” alata . It was, however, difficult to determine which species should be assigned to “ P.” alata , because the species was poorly defined and figured in the original description ( Crosse 1866). In addition, the syntype of “ P.” alata was in poor condition. The wing-like ribs and the outer peristome were broken, and the apical whorls were lost, indicating that data on some taxonomic characters is not available for the syntype ( Figs. 26A 1 –A 4 ). Despite the damage to the syntype, some diagnostic characters of the species are evident. These include the strongly protruded aperture, the strongly reflected inner peristome which is very widely expanded all around, the almost reduced axial ribs above the aperture, the parietal margin of the inner peristome located near the middle level of the upper body whorl, and the shell size being very large even without the apical whorls ( Figs. 26A 1 –A 4 ).

The interspace between the inner and outer peristomes of the syntype was unusually narrow ( Fig. 26A 4 ), however, this type of variant does occur within this species ( Fig. 26C ). A revised description of H. alata is provided here based on the c.a. 400 specimens collected from 13 localities, as the original description was not sufficient for species identification. The type locality of “P.” alata is noted as “Nermaleh” by Crosse (1866). Although we have not yet collected this species from the type locality, Ngermalk (=Nermaleh), the island falls within the distribution range of the species.

H. alata is distinguished from other large-sized Hungerfordia species with wing-like ribs by the following features: the strongly protruded aperture; the very widely expanded outer peristome; the thickened, strongly reflected, and very widely expanded inner peristome; the parietal margin of the inner peristome located near the middle level of the upper body whorl; the wide interspace between the inner and outer peristomes, which has a series of very low riblets on the outer surface; and the shell size being the largest among winged Hungerfordia species (the largest within the genus). In addition to the diagnostic characters mentioned here, H. alata also differs from related species in other respects. For instance, H. alata differs from H. subalata by the absence of short and lamellar growth wrinkles above the suture of the last 1–2 whorls, the presence of an apical septum, and the absence of wing-like projections of the ribs above the aperture. H. alata differs from H. lamellata by the presence of an apical septum, the absence of axial plicae inside the constriction, and the shell color being whitish. H. alata differs from H. papilio by the umbilicus being closed in adult, the narrower wing-like projection of the ribs, and the axial ribs being never synchronized. H. alata differs from H. pteropurpuroides by the shell size being always larger in sympatric populations, the smooth inner surface of the outer peristome, the reduced ribs above the aperture being more strongly folded, and the absence or poor development of growth wrinkles below the suture on the penultimate whorl.

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 10. Opercula of Palaina (Eupalaina) and Hungerfordia species. (A) P. (E.) moussoni Crosse, 1866, B0229; (B) P. (E.) dimorpha Crosse, 1866, B0087; (C) P. (E.) sp.-18, longitudinal section, B0082; (D) P. (E.) patula Crosse, 1866, B0204; (E) H. polymorpha (Crosse, 1866), B0049; (F) H. pelewensis Beddome, 1889, B0046; (G) H. polymorpha (Crosse, 1866), longitudinal section, B0049; (H) H. alata (Crosse, 1866), B0058. Oblique view of the outer surface, oblique view of the inner surface, and vertical view of the inner surface are shown from left to right in Figs. A, B, E, and F. Oblique view of the inner surface and vertical view of the inner surface are shown from left to right in Figs. D and H. Scale bars, 0.5 mm (A–B, D, E–F, H), 0.1 mm (C, G). All specimens, UMUTZ-MG.

FIGURE 11. Variation of shell shape and sculpture within and among Palaina (Eupalaina) and Hungerfordia species. (A) P. (E.) moussoni Crosse, 1866, shell height 2.8 mm, B0272; (B) P. (E.) sp.-15, shell height 2.6 mm, B0090; (C) P. (E.) strigata Crosse, 1866, shell height 4.2 mm, B0205; (D) P. (E.) patula Crosse, 1866, shell height 4.9 mm, B0204; (E) P. (E.) wilsoni Crosse, 1866, shell height 3.2 mm, B0296; (F) H. polymorpha (Crosse, 1866), shell height 3.8 mm, B0049; (G) H. sp.- 23, shell height 1.3 mm, B0149; (H) H. sp.-13, shell height 5.1 mm, B0250; (I) H. triplochilus sp. nov., shell height 5.9 mm, B0158; (J) H. alata (Crosse, 1866), shell height 7.4 mm, B0058; (K1, K2) H. goniobasis goniobasis sp. et subsp. nov., shell height 3.1 mm, B0092; (L1, L2) H. elegantissima sp. nov., shell height 3.4 mm, B0375; (M) H. pelewensis Beddome, 1889, shell height 3.1 mm, B0651; (N1, N2) H. pelewensis Beddome, 1889, shell height 3.1 mm, B0046. Arrow heads show positions of the constriction. All specimens, UMUTZ-MG.

FIGURE 25. Hungerfordia alata (Crosse, 1866). (A1–A4) Loc. Ko2-2, B1396a; (B) columellar tooth (dorsal view), Loc. Ko2- 2, B1396b; (C) axial ribs above the aperture (after removal of the inner peristome), Loc. Ko2-2, B1396a; (D) sculpture on the penultimate whorl, Loc. Ko2-2, B1396c; (E) sculpture above the suture of the last whorl, Loc. Ch8-2, B1396; (F1–F3) Loc. Ko2-2, B1396d; (G) apical septum, a partially opened specimen, Loc. Ko2-2, B1396; (H) umbilical view of a specimen after removal of the winged ribs, only the last whorl shown, Loc. Ko2-2, B1396e; (I1, I2) Loc. BA5-2, B0446; (J) Loc. Ch5-1, B0523a; (K) a reddish specimen from Loc. Ub7-2, B1062; (L1, L2) outer surface, and (L3, L4) inner surface of operculum, Loc. Ko2-2, B1396. Scale bars, 1mm (A–K), 0.5 mm (L). All specimens, UMUTZ-MG.

FIGURE 26. Hungerfordia alata (Crosse, 1866). (A1–A4) Syntype of “Palaina” alata, MNHN 26601; (B1, B2) original labels of the syntype; (C) a fresh specimen with a narrow interspace between the inner and outer peristomes, Loc. Ch5-1, UMUTZ- MG-B0523b. Scale bar, 1mm.

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 2–3. Enlarged maps of Palau islands showing collecting sites. Top (Fig. 2), map of southern part of Babeldaob island; bottom (Fig. 3), map of Koror island and its neighboring islands or islets. Abbreviations of the collecting sites are listed in Table 2.

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.