Hungerfordia echinata tubulispina 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 : 35-37

Hungerfordia echinata tubulispina K. Yamazaki and Ueshima subsp. nov.

( Figs. 9F , 17 , 29E )

Materials examined. Holotype. Limestone outcrop along a small river, north of Ngeream (Loc. BA 3-1), Airai state, Babeldaob island, Palau. Collected by R. U. and K. Y. on June 27, 2005. UMUTZ-MG-B0169 T . Paratypes. Same data as holotype, 90 specimens, UMUTZ-MG-B0169 .

Diagnosis. Shell generally similar to H. echinata echinata but differs by the following features: axial ribs more widely spaced than the nominal subspecies, upper margin of ribs above the spiny projections (between the suture and spines) indistinct or less protruded; spiny projections of the ribs almost tubular, narrower; growth wrinkles between the spiny ribs below the suture weaker. Distribution restricted to a limestone outcrop which is isolated from distribution range of the nominal subspecies.

Description. Shell ( Figs. 17A–I , 29E ). Shell sinistral, medium-size to large for Hungerfordia species , fusiform or conical, last whorl or penultimate whorl widest when removing the expanded ribs and peristomes. Shell color white, occasionally colored yellowish brown around the closed umbilicus, upper whorls usually colored yellow or light brown with the color becoming deeper toward the apex or the apical septum (apical whorls above the apical septum always uncolored). Whorls 6.5–7.5, convex or obtusely angulate at the periphery 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, followed by a weak swelling of whorl, associated with abrupt reduction of the spiny ribs, internally without palatal plica except for a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1+3/4 to 2 whorls, apical whorl almost smooth, lower whorl faintly punctated below the suture. Apical septum present or absent. Axial ribs developed on the teleoconch, oblique to the coiling axis, strongly protruded as tubular spines on most whorls; ribs on first 1/3 whorls of teleoconch low, closely spaced, not folded; ribs on the subsequent whorls (except above the aperture) highly protruded as tubular spines, widely spaced (10–13 ribs in a whorl), not synchronized with those on previous whorls, strongly curled at the periphery; upper margin of the ribs above the tubular spines (between the suture and spines) low, indistinct or hardly protruded; spiny projections on the ribs almost tubular, with a blunt and opened tip, with a narrow longitudinal slit at the adapertural side, very high, slender, almost straight, narrow, arising near the periphery (at some distance below the suture), disappeared just below the periphery, lower margin overlapped with or close to the upper margin at the base, protruded rather upward on most whorls, becoming protruded laterally to rather downward on last 3/4 whorls, with fine spiral sculptures on the outer surface; ribs above the aperture (ribs on last 1 to last 3/4 whorls around the constriction) abruptly becoming very closely spaced and very low, without any spiny projections, becoming less folded at the periphery toward the constriction. Interspace between the spiny ribs with fine growth wrinkles; upper growth wrinkles developed below the suture on lower whorls, low, fine; lower growth wrinkles occasionally present above the suture of the last 1–2 whorls, very weak, fine, rather long (extending near the periphery), almost vertical. Spiral sculptures present throughout teleoconch, fine, weak, extending on outer surface of the tubular spines and outer peristome, sinuous in high magnification. Base convex, rather smooth, without basal keel, occasionally with slightly elevated axial ribs. Axial protrusions of shell wall (along the spiny ribs) weakly developed on last 3/4 whorls, hidden by the tubular spines (visible after removal of the tubular spines), abapertural side steep and narrow, adapertural side convex and much wider than the abapertural one in umbilical view. Umbilicus closed in adult. Aperture hardly tilted against the coiling axis, slightly or hardly protruded; columellar axis within aperture almost vertical. Columellar tooth reduced or very weakly developed deeply inside the aperture. Peristome double, expanded; outer peristome more or less expanded beyond the inner one at the palatal and basal sides, with rounded palatal and baso-columellar edges, weakly folded at the periphery or not, weakly reflected, with fine and concentric growth wrinkles on the inner surface; inner peristome pentagonal or squarish circular, occasionally with a rounded angular edge, expanded all around, hardly reflected, strongly protruded from outer one, angular and parietal margin located slightly below middle level of the upper body whorl. Interspace between the inner and outer peristomes rather wide, almost smooth or with a series of fine and very low growth lines on the outer surface, gradually constricted at the basal and palatal sides, then gradually expanded toward the aperture; uppermost margin ascending onto the penultimate whorl toward the aperture in left lateral view.

Dimensions. Shell height 4.7–5.7 mm, diameter 3.8–4.4 mm, suture width 2.2–2.9 mm, peristome height 1.8– 2.1 mm.

Operculum ( Figs. 17J 1 –J 4 ). Operculum corneous, multispiral, circular, thin, transparent, amber colored, almost flat or weakly concave; outer surface smooth; inner surface with a low, weak, arcuate ridge neat the columellar margin.

Penis. Penis absent.

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

Distribution and ecology. Endemic to Palau: only known from the type locality, a narrow limestone outcrop isolated from distribution range of the nominal subspecies. The subspecies inhabits limestone rocks.

Remarks. H. echinata tubulispina differs from the nominal subspecies by the spiny projection of the ribs being tubular, the upper margin of the ribs (between the suture and the tubular projections) being less flared or indistinct, the more widely spaced axial ribs, and the axial protrusions on the last 3/4 whorl being more strongly developed.

Etymology. The subspecific name, derived from Latin tubulus (=tubular) and spina (=spine), refers to the tubular spines on the axial 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 17. Hungerfordia echinata tubulispina subsp. nov. (A1–A4) A topotypic paratype, B0169a; (B) columella (dorsal view), (C) axial ribs above the aperture (after removal of parietal margin of the outer peristome), (D1) sculpture on the last 1.25–1.5 whorls, and (D2) sculpture on the 1.5–1.25 whorls of topotypic paratypes (B0169a, b); (E1–E4) holotype, B0169T; (F) umbilical view of last whorl, and (G) front view of entire shell of a topotypic paratype after removal of the spiny ribs (B0169c); (H, I) topotypic paratypes, B0169d, e; (J1, J2) outer surface, and (J3, J4) inner surface of operculum, a topotypic paratype, B0169. Scale bars, 1mm (A–K), 0.5 mm (J). 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.