Hungerfordia echinata echinata 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 : 32-33

Hungerfordia echinata echinata K. Yamazaki and Ueshima sp. et subsp. nov.

( Figs. 9E , 16 , 29D )

Materials examined. Holotype. Limestone outcrop of Oikull (Loc. BA 8-7), Airai state, Babeldaob island, Palau. Collected by R. U. and M. Y. on March 4, 2011. UMUTZ-MG-B1441 T . Paratypes. Babeldaob: Loc. BA 5-1, 44 specimens, 12/XI/2006, UMUTZ-MG-B0437; Loc. BA 6-1, 85 specimens, 21/X/2007, UMUTZ-MG-B0662; Loc. BA 7-1, 123 specimens, 1/II/2010, UMUTZ-MG-B1084; Loc. BA 8-7, 59 specimens, 4/III/2011, UMUTZ-MG- B1441. Pkulaklim islet of Babeldaob: Loc. BA 5-4, 9 specimens, 12/XI/2006, UMUTZ-MG-B0469; Loc. BA 5-5, 9 specimens, 12/XI/2006, UMUTZ-MG-B0477; ditto, 84 specimens, 1/III/2011, UMUTZ-MG-B1300; Loc. BA 6- 2, 1 specimen, 21/X/2007, UMUTZ-MG-B0736 .

Diagnosis. Shell sinistral, medium-size to large for Hungerfordia species , fusiform. Shell color white or yellow. Constriction located above the aperture, associated with abrupt reduction of the spiny ribs. Apical septum occasionally present. Axial ribs on most whorls highly protruded and strongly folded at the periphery as spines, widely spaced; upper margin of the ribs above the spiny projection (between the suture and spines) distinct, slightly but prominently protruded (particularly below the suture); spiny projections very high, slender, folded, narrow, arising at some distance below the suture; ribs above the aperture very closely spaced, low, without spiny projection. Interspace between the spiny ribs with characteristic growth wrinkles; growth wrinkles developed below the suture on the last 2 whorls, low, distinct, lamellar. Spiral sculptures fine. Aperture hardly tilted. Columellar tooth reduced or very weakly developed. Peristome double, widely expanded; outer peristome expanded beyond the inner one, with rounded palatal and baso-columellar edges; parietal margin of the inner peristome located near or below the middle level of the upper body whorl. Interspace between the outer and inner peristomes wide, gradually constricted at the mid portion with a series of very low growth riblets on the outer surface, then expanded toward the aperture with rather smooth outer surface.

Description. Shell ( Figs. 16A–J , 29D ). Shell sinistral, medium-size to large for Hungerfordia species , fusiform, penultimate whorl widest when removing the protruded ribs and peristomes. Shell color white or semitransparent, upper whorls usually colored yellow (rarely reddish brown) with the color becoming deeper toward the apex or the apical septum (apical whorls above the apical septum always uncolored), or yellow throughout whorls. Whorls 6–7, convex or obtusely angulate at the middle level of the spiny ribs; 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 the spiny ribs, internally without palatal plica except a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1.75–2 whorls, apical whorl smooth, lower whorl finely punctated. Apical septum present or absent. Axial ribs developed on the teleoconch, oblique to the coiling axis, strongly developed as spines on most whorls; ribs on first 1/4–1/3 whorls of the teleoconch low, closely spaced, gradually becoming folded at the periphery; ribs on the subsequent whorls (except above the aperture) highly protruded and strongly folded at the periphery as spines, widely spaced (15–20 ribs in a whorl), not synchronized with those on the previous whorls; upper margin of the ribs above the spiny projection (between the suture and spines) distinct, slightly but prominently protruded (particularly below the suture on upper whorls); spiny projections of the ribs very high, slender, weakly pointed, trough-shaped, folded almost horizontally, narrow, arising at some distance below the suture (arising near periphery of a whorl), protruded slightly upward on upper whorls, becoming protruded laterally on the last 1.5 whorls, upper margin folded over the lower margin, lower margin extended below to the suture of the next 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 very low and very closely spaced, without spiny projections, becoming less folded at the periphery, slightly elevated just below the suture. Interspace between the spiny ribs smooth on the upper whorls, with characteristic growth wrinkles on lower whorls; growth wrinkles developed below the suture on the last 2 whorls, low, somewhat lamellar. Spiral sculptures present throughout the teleoconch, fine, weak, extended on outer surface of the spiny ribs and the outer peristome, sinuous in high magnification. Base convex, without basal keel, frequently with slightly elevated axial ribs. Axial protrusions of shell wall (along the spiny ribs) weakly developed on last 3/4 whorl, hidden by the spiny ribs, abapertural side narrow, adapertural side weakly convex and much wider than the abapertural one in umbilical view. Umbilicus closed in adult. Aperture hardly tilted against the coiling axis, hardly protruded; columellar axis within aperture almost vertical. Columellar tooth weakly developed or reduced, recessed deeply within the aperture when present. Peristome double, widely expanded; outer peristome expanded beyond the inner one at the palatal and basal sides, with rounded palatal and baso-columellar edges, with fine and concentric growth wrinkles on the inner surface; inner peristome strongly protruded from the outer one, expanded all around, parietal margin located near or below the middle level of the previous body whorl. Interspace between the outer and inner peristomes wide, gradually constricted (at the basal and palatal sides) with fine and very low growth riblets on the outer surface, then expanded toward the aperture with rather smooth outer surface; uppermost margin ascending onto the penultimate whorl toward the aperture in left lateral view.

Dimensions. Shell height 4.6–5.6 mm, diameter 3.1–4.1 mm, suture width 2.0–2.5 mm, peristome height 1.9– 2.2 mm.

Operculum ( Figs. 16K 1 –K 4 ). Operculum corneous, multispiral, circular, transparent, amber colored, thin, flat; outer surface smooth; inner surface with a low, weak, arcuate ridge near the columellar margin.

Radula ( Figs. 9E ). 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 and wide major cusp, without inner nor outer cusp, basal plate obliquely elongated. Inner marginal teeth shorter than the lateral teeth, elongated, with a wide major cusp, with a slender inner cusp, with a small outer cup. Outer marginal teeth shorter than the inner marginal, with a large, wide and blunt major cusp, with a slender inner cusp, without outer cusp.

Penis. Penis absent.

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

Remarks. H. echinata echinata is distinguished from all other spiny Hungerfordia species by the fusiform shell shape; the spiny ribs being more closely spaced; having slender and narrow spiny projections on the ribs; the upper margin of the ribs (between the suture and spiny projections) being distinctly protruded; and the ribs above the aperture, which are densely spaced and lacking of any spiny projections.

Etymology. The specific name, derived from Latin echinatus (=prickly), refers to the shell with many spiny 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 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 16. Hungerfordia echinata echinata sp. et subsp. nov. (A1–A4) A paratype from Loc. BA5-1, B0437a; (B) columellar tooth (left lateral view), and (C) axial ribs above the aperture of paratypes from Loc. BA5-1 (B0437a, b); (D1) sculpture on the last 2–1.5 whorls, and (D2) sculpture on the last 1–1.5 whorls of a paratype from Loc. BA5-1, B0437a; (E1–E4) holotype, B1441T; (F) umbilical view of a paratype after removal of the spiny ribs, only the last whorl shown, Loc. BA7-1, B1084b; (G) a paratype from Loc. BA6-1, B0662; (H) a paratype with broken spines from Loc. BA5-1, B0437c; (I) a paratype from Loc. BA8-2, B1300; (J) apical septum, a partially opened paratype from Loc. BA5-1, B0437b; (K1, K2) outer surface, and (K3, K4) inner surface of operculum, a paratype from Loc. BA5-1, B0437. Scale bars, 1mm (A–J), 0.5 mm (K). 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.