Hungerfordia pelewensis Beddome, 1889

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 : 21-24

Hungerfordia pelewensis Beddome, 1889

( Figs. 7D , 8A, 8 E 1 , 9A , 10F , 11M–N , 12 , 29O )

Hungerfordia pelewensis: Beddome, 1889, pp. 115–116 , pl. 6, fig. 10.

Hungerfordia pelewensis: Crosse, 1892, pp. 280–282 , pl.4, fig. 2.

Hungerfordia pelewensis: Kobelt & Moellendorff, 1898, p. 135 .

Hungerfordia pelewensis: Kobelt, 1902, pp. 422–423 .

Hungerfordia pelewensis: Thiele, 1929, p. 110 .

Hungerfordia pelewensis: Wentz, 1939, p. 483 , fig. 1250.

Materials examined. Possible syntypes. Koror, 5 specimens, collected by R. H. Beddome, Melvill-Tomlin collection, NMW.1955.158.1903 ( National Museum of Wales ), temporary number (1587) . Additional materials. Babeldaob: Loc. BA 4-1, 33 specimens, 7/VII/2006, UMUTZ-MG-B0283; Loc. BA 5-2, 7 specimens, 12/XI/2006, UMUTZ-MG-B0450; Loc. BA 6-3, 5 specimens, 21/X/2007, UMUTZ-MG-B0679; Loc. BA 6-4, 2 specimens, 21/ X/2007, UMUTZ-MG-B0698; Loc. BA 8-4, 1 specimen, 1/III/2011, UMUTZ-MG-B1318; Loc. BA 8-5, 11 specimens, 1/III/2011, UMUTZ-MG-B1331. Koror and its satellite islets: Loc. Ko2-2, 65 specimens, 7/XI/2004, UMUTZ-MG-B0046; Loc. Ko2-2, 2 specimens, 28/VI/2005, UMUTZ-MG-B0180; Loc. Ko5-6, 12 specimens, 14/ XI/2006, UMUTZ-MG-B0542. Ngermalk: Loc. Nm4-1, 3 specimens, 8/VII/2006, UMUTZ-MG-B0316. Ulebsechel: Loc. Ub6-1, 5 specimens, 22/X/2007, UMUTZ-MG-B0752; Loc. Ub7-1, 3 specimens, 31/I/2010, UMUTZ-MG-B1047; Loc. Ub7-2, 15 specimens, 31/I/2010, UMUTZ-MG-B1059; Loc. Ub7-3, 2 specimens, 31/I/ 2010, UMUTZ-MG-B1069; Loc. Ub7-4, 4 specimens, 31/I/2010, UMUTZ-MG-B1075; Loc. Ub8-1, 36 specimens, 3/III/2011, UMUTZ-MG-B1428. Ngerchaol: Loc. Ch6-2, 3 specimens, 22/X/2007, UMUTZ-MG- B0722; Loc. Ch8-1, 13 specimens, 3/III/2011, UMUTZ-MG-B1387. Ngeruktabel: Loc. Gk2-2, 7 specimens, 11/ XI/2004, UMUTZ-MG-B0159; Loc. Gk4-4, 1 specimen, 11/VII/2006, UMUTZ-MG-B0383; Loc. Gk4-5, 6 specimens, 11/VII/2006, UMUTZ-MG-B0398; Loc. Gk2-2, 1 specimen, 12/VII/2006, UMUTZ-MG-B0432; Loc. Gk5-5, 119 specimens, 18/XI/2006, UMUTZ-MG-B0651; Loc. Gk5-5, 29 specimens, 22/X/2007, UMUTZ-MG- B0728; Loc. Gk6-2, 12 specimens, 22/X/2007, UMUTZ-MG-B0742; Loc. Gk7-6, 1 specimen, 30/I/2010, UMUTZ-MG-B1002. Ongael and other satellite islets of Ngeruktabel: Loc. Gk1-2, 3 specimens, 28/V/2003, UMUTZ-MG-B0035; Loc. Gk1-2, 11 specimens, 10/XI/2004, UMUTZ-MG-B0142; Loc. Gk1-2, 3 specimens, 10/ VII/2006, UMUTZ-MG-B0344; Loc. Gk4-2, 17 specimens, 10/VII/2006, UMUTZ-MG-B0360; Loc. Gk7-4, 53 specimens, 29/I/2010, UMUTZ-MG-B0965; Loc. Gk8-2, 8 specimens, 25/II/2011, UMUTZ-MG-B1139; Loc. Gk7-1, 5 specimens, 27/I/2010, UMUTZ-MG-B0899; Loc. Gk7-1, 19 specimens, 27/I/2010, UMUTZ-MG-B0906 .

Diagnosis. Shell sinistral, small for Hungerfordia species , depressed or low conical, wider than the height. Shell color white or yellow. Upper whorls (higher than the last whorl) sharply keeled at the periphery, flat on the upper side above the periphery. Last whorl abruptly narrowed, distinctly shaped and sculptured from the preceding whorls; last 1/8 whorls never ascending onto the penultimate whorl in left lateral view. Constriction located a half whorl behind the aperture, not associated with prominent change of the axial ribs. Protoconch roughly punctated. Axial ribs on upper whorls (higher than the last whorl) closely spaced at first, gradually becoming widely spaced, strongly protruded and folded at the periphery as spines, very low on upper side above the periphery; spiny projections of the ribs protruded beyond the periphery, depressed almost horizontally. Ribs on the last whorl very closely spaced, very low, without spiny projections. Spiral sculptures fine. Base rather flat, with a prominent basal keel on the last 3/4 whorls. Umbilicus narrowly opened. Aperture strongly turned downward, opened almost horizontally, recessed inside the outer peristome. Columellar tooth absent or weakly developed. Peristome double: outer peristome expanded beyond the inner one at the palatal side, continuous with the basal keel, with fine growth lines on the inner surface; inner peristome semi-circular, hardly protruded from the outer one, parietal margin located below the base of the upper body whorl.

Description. Shell ( Figs. 7D , 11M– N 2 , 12A–K , 29O 1 –O 2 ). Shell sinistral, small for Hungerfordia species , depressed or low conical, wider than the height, last whorl widest or last 2 whorls almost equally widest; last whorl abruptly narrowed, distinctly shaped and sculptured from the preceding whorls with a sudden change. Shell color white, occasionally yellow throughout the whorls or colored only on the apical whorls. Whorls 5–6, sharply keeled at the periphery on upper whorls higher than the last whorl, not convex on teleoconch whorls, upper side above the peripheral keel almost flat, distinctly keeled or carinated at the base on the last whorl; last 1/8 whorls never ascending onto the penultimate whorl in left lateral view, always below the periphery of the penultimate whorl. Suture impressed on apical two whorls, hardly impressed on the subsequent whorls except the last one, running slightly inside the periphery of penultimate whorl on the last 1 to last 1/3 whorls. Constriction located a half whorl behind the aperture, less prominent in external view but recognizable by the weakly constricted suture in oblique umbilical view, not associated with prominent change of the axial ribs, internally without palatal plicae except a low axial-crest caused by the constriction. Tuba c.a. 1/2 whorl, unusually short for Hungerfordia species. Protoconch 1–1.25 whorls, somewhat mammillated in front view, strongly and roughly punctated, showing irregular net-like sculpture, whorls convex. Apical septum absent. Peripheral keel present on upper teleoconch whorls higher than the last whorl, very sharp, serrated with short spiny projections of the ribs in apical view, suddenly disappeared on the last whorl. Axial ribs developed on the teleoconch, showing a sudden change between the last whorl and the higher whorls: ribs on upper whorls (higher than the body whorl) strongly oblique against the coiling axis, low except the peripheral spines, closely spaced (6–8 ribs in a quarter whorl) on apical whorls, gradually becoming widely spaced (4 ribs in a quarter whorl) on the penultimate whorl, not synchronized with those on the previous whorls, folded and protruded at the periphery as spines; upper margin of the ribs above the spiny projections (between the suture and the periphery) low, but slightly elevated; spiny projections on the ribs protruded beyond the periphery, rather short, obtusely pointed with rounded tip in apical view, depressed almost horizontally, flat, narrow, arising just above the periphery (at some distance below the suture), disappeared just below the periphery, folded at the periphery, upper margin folded over and extended far beyond the lower margin, gradually becoming higher and more widely spaced, reaching the maximum height and the widest intervals at about 1.5 whorls behind the aperture, then gradually becoming lower and more closely spaced toward the last whorl, suddenly disappeared on the last whorl; ribs on last whorl abruptly becoming very closely spaced and very low, not folded nor protruded on the initial 1/8 whorls, partially distorted by the basal keel on the last 3/4 whorls, becoming less oblique than those on the upper whorls, somewhat sinuous on lateral walls above the basal keel, not showing prominent change around the constriction. Interspace between the spiny ribs almost smooth, without axial sculpture except some faint growth lines on the penultimate whorl. Spiral sculptures present throughout the teleoconch, fine, rather prominent, extended on outer surface of the spiny projections of the ribs, sinuous in high magnification. Base flat, with a prominent basal keel. Basal keel developed on the last 3/4 whorls, variable in the degrees of the development from weakly carinated to highly protruded with a sharp edge, arising at short distance below the periphery on the last 3/4 whorls, becoming higher toward the aperture and continued to the outer peristome. Basal surface smooth in juvenile, with very low, weak and very closely spaced ribs on the last whorl in adult. Lateral wall above the basal keel on the last whorls steep, flat, nearly vertical or slightly inclined toward the columella on the last 3/4 to last 1/3 whorls, becoming to inclined toward the suture on the last 1/3 whorls. Axial protrusion of shell wall (along the ribs) not developed on the last whorl. Umbilicus narrowly opened in adult, partially hidden by the columellar margin of the inner peristome, visible in oblique umbilical view. Aperture strongly turned downward, opened almost horizontally toward the base, recessed inside the anterior margin of the outer peristome, slightly protruded downward from base of the previous whorl at the parietal side; columellar axis within aperture oblique against the coiling axis. Columellar tooth absent or present, weak and short when present. Peristome double: outer peristome expanded beyond the inner one at the palatal side, undeveloped at the basal and the columellar sides, extended forward beyond the aperture at the palatal side, continuous with basal keel, with a series of fine growth lines on the inner surface; inner peristome semi-circular in umbilical view, hardly or very slightly protruded from the outer one at the palatal side, erected at the columellar and basal sides, reflected and expanded at the basal and columellar sides, but less expanded at the palatal and the parietal sides, parietal margin located below and slightly protruded downward from base of the previous whorl.

Dimensions. Shell height 2.4–4.1 mm, diameter 3.1–4.8 mm, suture width 1.8–2.7 mm.

Operculum ( Figs. 10F , 12L 1 –L 4 ). Operculum corneous, multispiral, circular, transparent, amber colored, thin, flat; outer surface smooth; inner surface with a low, thin, weak, arcuate ridge near the columellar margin.

Penis ( Fig. 7D ). Penis absent.

Radula ( Figs. 8A 1 –A 4 , 8E 1 , 9A ). Radula of specialized type of taenioglossate; ribbon very long. Central tooth very large, with a very wide and large central cusp, with a pair of small 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 one or two vestigial inner cusps, without outer cusp, basal plate obliquely elongated. Inner marginal teeth shorter than the lateral teeth, with a large and wide major cusp, with two slender inner cusps and a small outer cup, basal plate slender. Outer marginal teeth with a large and blunt major cusp, with two slender inner cusps, without outer cusp.

Variations. H. pelewensis shows some inter- or intra-populational variations in the shell shape, color, sculpture, and development of the columellar tooth. The spire is depressed ( Figs. 11 N 1 , 12J ) or somewhat elevated ( Figs. 11M , 12K ). The basal keel is sharply protruded and delineating the flat base and steep lateral wall ( Figs. 12A 1 –A 5 , 12B ), or weakly angulate with a rather convex base ( Figs. 12C 2 –C 3 , 12E 1 –E 3 ). The columellar tooth is usually absent ( Figs. 12A, 12B, 12F 2 ), but weakly developed in some populations ( Figs. 11M , 12C 2 –C 3 , 12F 1 ). Yellow color morph occasionally occurs ( Fig. 12J ).

Distribution and ecology. Endemic to Palau: Babeldaob (southern coastal limestone area), Koror (eastern limestone area), Ngermalk, Ngerchaol, Ngeruktabel islands and their satellite islets. The species inhabits limestone rocks.

Remarks. H. pelewensis , the type species of Hungerfordia , is one of the most peculiar-shaped diplommatinids in the world. This species is easily distinguished from all other Palauan diplommatinids by the depressed or low conical spire with a sharp peripheral keel on upper whorls, the presence of a basal keel, the last whorl being distinctly shaped and sculptured from the preceding whorls, and the constriction located only a half whorl behind the aperture. H. goniobasis is comparable to H. pelewensis in having a basal keel continuing to the outer peristome, and an aperture recessed inside the outer peristome. However, H. goniobasis is readily distinguished in its much higher spire, having a longer tuba of 7/8 whorls, the absence of a sharp peripheral keel, and in having developed spiny ribs on the last whorl. H. elegantissima is also comparable to H. pelewensis in having an aperture, which is strongly turned downward, and a short tuba of only a half whorl. Nevertheless, H. elegantissima is distinguished from H. pelewensis by having much longer spiny ribs, which persist throughout the whorls, the absence of a basal keel, and its last 1/8 whorls being decoiled downward.

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 7. Male soft parts of Palaina (Eupalaina) and Hungerfordia species. (A1, A2) P. (E.) patula Crosse, 1866, B0753; (B) P. (E.) sp.-20, live condition, B0732; (C) H. inflatula (Crosse, 1866), B0217; (D) H. pelewensis Beddome, 1889, live condition, B0651; (E) H. polymorpha (Crosse, 1866), live condition, B0659. Arrow heads indicate penes. Scale bars, 1mm. All specimens, UMUTZ-MG.

FIGURE 8. Radulae and buccal masses of Hungerfordia and Palaina (Eupalaina) species. (A1–A4) H. pelewensis Beddome, 1889, B0283; (B1–B4) H. polymorpha (Crosse, 1866), B0315; (C1–C4) P.(E.) sp.-20, B0595; (D1, D2) P.(E.) patula Crosse, 1866, B0320; (E1) H. pelewensis Beddome, 1889, buccal mass, B0283; (E2) H. polymorpha (Crosse, 1866), buccal mass, B0315; (E3) P. (E.) patula Crosse, 1866, buccal mass, B0320. Scale bars, 10 µm (A–D), 0.5 mm (E1–E3). All specimens, UMUTZ-MG.

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 12. Hungerfordia pelewensis Beddome, 1889. (A1–A5) An adult from Loc. Ko2-2, B0046a; (B) an adult from Loc. Ko5-6, B0542; (C1–C3) an adult from Loc. Gk5-5, B0651a; (D1–D3) a juvenile, and (E1–E3) a subadult from Loc. Ub6-1 (B0752a, b); (E4) enlarged Fig. E2, showing an abrupt change of the sculpture and whorl shape on the last whorl; (F) subapical views of broken adults showing the columellar tooth and the constriction: (F1) an adult from Loc. Gk5-5, B0651b; (F2) an adult from Loc. Ko2-2, B0046b; (G) a young subadult from Loc. Gk5-5, B0752c; (H) sculpture on penultimate and the higher two whorls, a subadult from Loc. Ub6-1, B0752; (I) protoconch, an adult from Loc. Ko2-2, B0651c; (J) an adult from Loc. BA4-1, B0283; (K) an adult from Loc. Gk5-5, B0046c; (L1, L2) outer surface, and (L3, L4) inner surface of operculum, Loc. Ko2-2, B0046. Arrow heads show position of the constriction. Scale bars, 1mm (A–G, J, K), 0.5 mm (H, I, L). 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 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.