Hungerfordia nodulosa M. Yamazaki and Ueshima

Yamazaki, Midori, Yamazaki, Kazunori, Rundell, J. & Ueshima, Rei, 2015, Systematic review of diplommatinid land snails (Caenogastropoda, Diplommatinidae) endemic to the Palau Islands. (3) Description of eight new species and two new subspecies of Hungerfordia, Zootaxa 4057 (4), pp. 511-538 : 527-530

Hungerfordia nodulosa M. Yamazaki and Ueshima sp. nov.

(Figs. 8, 12K1–2)

Materials examined. Holotype. Southern coast of western part of Bkulschuul island (Loc. Uo8-2), Ulong islands, Palau. Collected by R. U. and M. Y. on Feb. 25, 2011. UMUTZ-MG-B1149T. Paratypes. Ulong: Loc. Uo7-1, 6 specimens, 27/I/2010, UMUTZ-MG-B0934; Loc. Uo8-2, 11 specimens, 25/II/2011, UMUTZ-MG-B1149; Loc. Uo8-4, 22 specimens, 27/II/2011, UMUTZ-MG-B1226.

Diagnosis. Shell sinistral, large for Hungerfordia species, conical. Shell color usually yellow on upper whorls, whitish on the last whorl, with two brown bands behind the aperture: upper band extended below the suture; lower band winding around the columella. Axial ribs developed on teleoconch; ribs on upper whorls (higher than the last whorls) strong, very widely spaced, weakly folded and shortly protruded at the peripheries of the whorls, elevated by axial protrusions of shell wall (along the ribs); ribs above the aperture closely spaced, low; ribs on the last 3/4 whorls strong, widely spaced, folded, partially and strongly elevated by axial protrusions of shell wall only at the peripheries of the whorls, with nodular swellings. Interspace between the widely spaced ribs with some closely spaced growth wrinkles below the suture. Aperture rather large; columellar axis within the aperture slightly oblique. Columellar tooth present, moderately developed. Peristome double. Outer peristome strongly developed, widely expanded beyond the inner peristome. Inner peristome squarish circular. Thickened lip developed behind the aperture, moderately wide; dorsal margin distinct, abruptly expanded from the preceding whorl as the outer peristome.

FIGURE 8. Hungerfordia nodulosa sp. nov. (A1–10) A topotypic paratype, Loc. Uo8-2, B1149a: (A10) sculpture on the penultimate whorl; (B1–6) holotype, B1149T; (C) brownish color variant, a paratype from Loc. Uo8-4, B1226; (D1–2) outer surface, and (D3–4) inner surface of operculum, a topotypic paratype, B1149. Scale bars, 1mm. All specimens, UMUTZ-MG.

Description. Shell (Figs. 8A–C, 12K1–2). Shell sinistral, thick, large for Hungerfordia species, conical, last whorl widest or last 2 whorls almost equally widest when excluding the thickened lip and peristomes; sides almost straight. Shell color usually yellow (occasionally reddish brown) on most whorls (higher than the last whorl), whitish on the last whorls, with two vague brown bands behind the aperture: upper band developed below the suture behind the outer peristome, becoming broader toward the aperture; lower band winding around the columella on the last 5/8 whorls, longer than the upper band. Whorls 5–6, slightly convex, but seemingly angulate at the peripheries of widely spaced ribs due to axial protrusions of the shell wall along the obliqued ribs, broadest (in longitudinal width) on the penultimate or the last whorl in dorsal view; last 3/4 whorls with characteristic nodular swellings along the ribs; last 1/8 whorls (including the thickened lip) expanded upward, ascending onto the penultimate whorl in left lateral view; last 1/4 whorls behind the outer peristome somewhat dorso-ventrally depressed at the base. Suture impressed; suture of a part of the last whorl occasionaly running slightly inside the angulate base (=basal keel) of the penultimate whorl. Constriction located above the parietal/collumellar junction of the aperture, internally without palatal plica except a low and axial crest caused by the constriction, associated with abrupt changes of the ribbing pattern. Tuba 7/8 whorls. Protoconch 3/4–1+1/4 whorls, almost smooth, very weakly and very finely punctated on the lower whorl. Apical septum absent. Axial ribs strongly developed on teleoconch, distinct throughout whorls, oblique to the coiling axis: ribs on first 1/3–1/2 whorls of teleoconch weak, closely spaced, very low, almost straight; ribs on the following 1/4–1/3 whorls of initial teleoconch gradually becoming stronger and more widely spaced; ribs on the subsequent whorls except the last whorl (ribs on the penultimate and the higher 2.5–3 whorls) strongly developed, very widely spaced (7–11 ribs in a whorl), elevated by axial protrusions of shell wall along the ribs, weakly folded and slightly protruded at the peripheries of the whorls, sharply edged, but never pointed at the shoulder, gradually becoming more closely spaced and less folded on the last 1+1/4 to last 1 whorls; ribs above the aperture (ribs on the last 1+1/8 to last 3/4 whorls around the constriction) closely spaced, low (but distinct), almost straight (not folded at the peripheries of the whorls); ribs on the last 3/4 whorls strongly developed, abruptly becoming very widely spaced again, folded and slightly protruded at the peripheries of the whorls, partially and characteristically elevated by axial protrusions of shell wall along the ribs, strongly elevated only along the central and folded part of the ribs (elevated only at the peripheries of the whorls), associated with nodular swellings, never elevated at the upper margin (between the suture and the periphery) and the lower (basal) margin (between the periphery and the columella). Interspace between the widely spaced ribs with interstitial growth wrinkles below and above the suture: upper growth wrinkles always developed below the suture on most whorls, closely spaced, moderately long, disappearing near the peripheries of the whorls; lower growth wrinkles occasionally present on the last 1+1/8 to last 1+1/4–2 whorls, weakly developed just above the suture of the next whorl, very short, much shorter than the upper wrinkles, closely spaced, occasionally and partially connected with the upper wrinkles by weak growth lines. Spiral sculpture present throughout teleoconch whorls, fine, prominent on the upper whorls, somewhat weakened on the last 3/4 whorls, sinuous in high magnification. Basal keel absent on the last whorl, but present on the penultimate and the higher few whorls, a trace of angulate base in younger stages, hardly visible in adult shell, but occasionally visible just above the suture of the last whorl in oblique umbilical view, narrow, associated with a very weak spiral depression. Axial protrusions of the shell wall (along the ribs) on the last 3/4 whorls characteristically developed, strongly developed only at the periphery of the whorls (developed only along the central and the folded parts of the ribs), never developed at the base and below the suture, with nodular swellings; abapertural side almost flat or faintly concave in oblique umbilical view, but seemingly convex in mid-umbilical view due to the obliqued axial ribs; adapertural side prominently convex, almost equally wide as the abapertural side in umbilical view. Base smooth except around the columella, convex on the last 1 to last 2/3 whorls, somewhat dorso-ventrally depressed on the last 1/4 whorls behind the outer peristome, with a weak circum-columellar fold; circum-columellar fold very weakly develped on the last 3/4 whorls around the columella, with fine and weak growth lines on its surface, expanded beyond the inner peristome at the columellar side in front view. Umbilicus closed in adult. Aperture rather large, not protruded, slightly tilted downward against the coiling axis in left lateral view; columellar axis within aperture rather oblique (tilted outward) against the coiling axis in front view. Columellar tooth present, moderately developed, emerged at the aperture, but never extended onto the inner peristome, deeply extended inward about 3/ 4 whorls. Peristome double. Outer pesitome strongly developed at the dorsal margin of the thickened lip, expanded beyond the inner peristome in front view; inner surface with fine and concentric growth lines; outer surface with fine spiral sculptures. Inner peristome squarish circular, moderately expanded, but less expanded at the upper palatal side, slightly expanded beyond the thickened lip at the basal side (in left lateral view), strongly protruded from the outer peristome; parietal margin located below the middle level of the upper body whorl. Thickened lip developed behind the aperture, moderately wide, with very fine growth lines on its outer surface, white, lacking of periostracum, almost cylidrically extended in umbilical view; dorsal margin distinct, abruptly expanded from the preceding whorl, with a developed outer peristome; upper most margin (= suture) ascending onto the penultimate whorl toward the aperture in left lateral view; base extended almost horizontally toward the aperture in left lateral view; palatal margin protruded beyond the penultimate whorl in apical view.

Dimensions. Shell height 5.3–6.2 mm, shell diameter 3.2–3.7mm, suture width 2.5–2.7 mm, peristome height 1.9–2.4 mm.

Operculum (Figs. 8D1–4). Operculum corneous, multispiral, circular, semi-transparent, amber-colored, thin, flat; outer surface smooth; inner surface with a very low, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula . Not examined.

Distribution and ecology. Endemic to Palau: Ulong islands. The species inhabits limestone rocks.

Remarks. H. nodulosa is similar to H. ringens ( Crosse, 1866) , but differs in the following ways: the axial ribs on the last 3/4 whorls are widely spaced, prominently folded and protruded at the peripheries of the whorls, and with characteristic nodular swellings; lateral fold, dorsal fold, and dorsal groove never developed on last 3/4 whorls; the axial ribs are also widely spaced at the dorsal side of the penultimate whorl (Figs. 12I, K). H. nodulosa is also similar to H. spinoscapula Yamazaki & Ueshima, 2015 , which coexists with the species in sympatry. H. nodulosa , however, differs from H. spinoscapula by the axial ribs being never sharply pointed at the shoulder, the strongly developed outer peristome, the absence of lateral fold and dorsal fold on the last 3/4 whorls, and the larger and broader shell in the sympatric populations (Figs. 12J, K).

Although most specimens of H. nodulosa are readily distinguished from H. robiginosa Yamazaki & Ueshima, 2015 by the yellow shell color, the brownish color variant of the species is very similar to H. robiginosa (Figs. 12K2, L). Brownish variant of H. nodulosa , however, differs from H. robiginosa by the following features: the axial ribs on the last 3/4 whorls are distinctly elevated at the peripheries of the whorls, associated with characteristic nodular swellings; the axial ribs on the penultimate and the higher 2 whorls are more widely spaced; the outer peristome is widely expanded beyond the inner peristome.

Etymology. The specific name, derived from Latin nodulosus, refers to the characteristic nodular swellings on the last 3/4 whorls.