Hungerfordia goniobasis goniobasis 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 : 40-42

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

( Figs. 9H , 11K , 19 , 29M )

Hungerfordia sp. : Cowie, 1996, p. 348, fig. 1Ba.

Materials examined. Holotype. Jellyfish lake , east of Mecherchar island (Loc. Mc2-1), Palau. Collected by R. U. on July 1, 2005. UMUTZ-MG-B0235 T . Paratypes. Mecherchar: Loc. Mc2-1, 5 specimens, 1/VII/2005, UMUTZ- MG-B0235; Loc. Mc6-1, 2 specimens, 23/X/2007, UMUTZ-MG-B0763.

Diagnosis. Shell sinistral, small for Hungerfordia species , slender conical. Shell color white or yellowish brown. Whorls obtusely angulate at the periphery on lower whorls; last 1/8 whorls expanded downward, never ascending onto the penultimate whorl in left lateral view. Constriction located above the aperture, associated with a weak reduction of the spiny ribs. Axial ribs on most whorls highly protruded and folded at the periphery as spines, very widely spaced; upper margin of the ribs above the spiny projections (between the suture and spines) very low, indistinct; spiny projections of the ribs very high, rather narrow, arising at some distance below the suture; ribs above the aperture somewhat more closely spaced, with rather shorter spiny projections. Interspace between the spiny ribs smooth. Spiral sculptures fine, rather prominent. Basal keel developed at base of the last whorls, sharp, continued to the outer peristome. Aperture distinctly small, tilted downward, recessed inside the outer peristome, located below and shortly protruded downward from base of the upper body whorl. Columellar tooth weak. Peristome double: outer peristome very widely expanded beyond the inner one at the palatal and basal sides, continued to the basal keel, with fine growth lines on the inner surface; inner peristome unusually small, squarish circular, hardly expanded, hardly protruded from the outer one; parietal margin of inner peristome almost horizontal, protruded downward and shortly separated from base of the upper body whorl. Distribution Mecherchar island.

Description. Shell ( Figs. 11K 1 –K 2 , 19A–H , 29M ). Shell sinistral, small for Hungerfordia species , slender conical, last whorl widest when removing the protruded ribs. Shell color white, apical whorls occasionally yellow or yellowish brown with the color becoming deeper toward the apex. Whorls 7–8, regularly coiled (increasing regularly in both width and height), convex in apical whorls, obtusely angulate at periphery of the spiny ribs on lower whorls; last 1/8 whorls expanded downward, never ascending onto the penultimate whorl in left lateral view. Suture impressed. Constriction located above the parietal/columellar junction of the aperture, less prominent in external view, associated with a weak reduction of the spiny ribs, internally without palatal plica except a low axial-crest caused by the constriction. Tuba 7/8–3/4 whorls. Protoconch c.a. 1.5 whorls, almost smooth or weakly punctated. Axial ribs developed on the teleoconch, oblique to the coiling axis, strongly developed as spines on most whorls; ribs undeveloped on the first 1/3–2/3 whorls of the initial teleoconch; ribs on the following 1/4 whorls of the initial teleoconch low, closely spaced, gradually becoming widely spaced, not folded; ribs on the subsequent whorls strongly protruded as spines, strongly folded at the periphery, very widely spaced (7–10 ribs in a whorl), not synchronized with those on the previous whorls; upper margin of the ribs above the spiny projections (between the suture and spines) low, indistinct; spiny projections of the ribs very high, weakly pointed, folded at the periphery, trough-shaped, rather narrow for spiny Hungerfordia species , arising at some distance below the suture (near periphery of a whorl), protruded laterally or slightly downward, slightly curved upward, upper margin folded over the lower margin, 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) more closely spaced and less protruded than those on the preceding and following whorls, with shorter but still developed spiny projections, folded at the periphery. Interspace between the spiny ribs smooth, without prominent axial sculpture except some faint growth lines. Spiral sculptures present throughout the teleoconch, fine, rather prominent, curved downward just above the spiny ribs, extended on outer surface of the spiny ribs and outer peristome, sinuous in higher magnification. Base with a strong basal keel. Basal keel developed at base of the last 3/4 whorls, sharply protruded, arising just after the constriction, continued to the outer peristome, with a series of fine growth wrinkles at the columellar side. Umbilicus closed in adult. Axial protrusions of shell wall (along the ribs) developed on the last 3/4 whorls. Aperture distinctly small, strongly tilted downward against the coiling axis, recessed inside the outer peristome, located below and slightly protruded downward (evidently separated) from base of the previous whorl; columellar axis within aperture almost vertical. Columellar tooth present just inside the aperture, very weak, short, located near the base. Peristome double; outer peristome strongly tilted downward against the coiling axis, very widely expanded beyond the inner one at the palatal and basal sides, lower palatal margin extended below like a spatula, continued to the basal keel, with a series of fine growth lines on the inner surface, with fine spiral sculptures on the outer surface; inner peristome unusually small, hardly protruded from the outer one, squarish circular, slightly expanded on the basal and columellar sides, with almost horizontal parietal margin which is shortly but evidently protruded downward from base of the upper body whorl, columellar side erected from the basal keel to form a narrow “pseudo-umbilicus”.

Dimensions. Shell height 3.1–3.3 mm, diameter 1.8–2.5 mm, suture width 1.1–1.2 mm, peristome height 0.6– 0.7 mm.

Operculum ( Figs. 19I 1 –I 4 ). Operculum corneous, multispiral, transparent, amber color, thin, flat; outer surface smooth; inner surface with a low, weak, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula ( Fig. 9H ). Radula of specialized type of taenioglossate; ribbon very long. Central tooth very large, with a very wide, large and blunt central cusp, with a pair of small lateral cusps; lateral teeth also large, with a very large major cusp, with a small inner cusp, without outer cusp; inner marginal teeth with a large major cusp, with two slender inner cusps, with a short outer cusp; outer marginal teeth with a large and blunt major cusp, two slender inner cusps, without outer cusp.

Distribution and ecology. Endemic to Palau. Type materials are obtained only from Mecherchar island. Cowie (1996) showed a line drawing of this species as Hungerfordia sp. from Beliliou (= Peleliu) island. H. goniobasis goniobasis inhabits limestone rocks.

Remarks. H. goniobasis goniobasis is easily distinguished from all other spiny Hungerfordia species by the very small and slender shell, the presence of a distinctive basal keel which continues to the outer peristome, the distinctly small and basally located aperture, the parietal margin of the inner peristome which is slightly separated downward from base of the upper body whorl, and the ribs above the aperture, which retain developed spiny projections.

Etymology. The specific name, derived from Greek gonia (=angle) and basis (=base), refers to the characteristic basal keel.

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 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 19. Hungerfordia goniobasis goniobasis sp. et subsp. nov. (A1–A5) A topotypic paratype, B0235a; (B) aperture, (C) columella (dorsal view), (D) axial ribs above the aperture (umbilical view), and (E) sculpture on the penultimate whorl of a topotypic paratype (B0235a); (F1–F5) holotype, B0235T; (G) a topotypic paratype, B0235b; (H1, H2) a paratype with short spiny ribs from Loc. Mc6-1, B0763; (I1, I2) outer surface, and (I3, I4) inner surface of operculum, a topotypic paratype, B0235. Scale bars, 1mm (A, D–H), 0.5 mm (B, C, I). 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.