Hungerfordia papilio stenoptera K. Yamazaki and Ueshima, 2013

YAMAZAKI, KAZUNORI, YAMAZAKI, MIDORI & UESHIMA, REI, 2013, Systematic review of diplommatinid land snails (Caenogastropoda, Diplommatinidae) endemic to the Palau Islands. (1) Generic classification and revision of Hungerfordia species with highly developed axial ribs , Zootaxa 3743 (1), pp. 1-71 : 61-65

publication ID	https://doi.org/ 10.11646/zootaxa.3743.1.1
publication LSID	lsid:zoobank.org:pub:1F36D59E-7737-4D50-8436-8584CF150DB2
persistent identifier	https://treatment.plazi.org/id/AF33878F-FFCE-6869-FF1F-DE1DE925A1A8
treatment provided by	Felipe
scientific name	Hungerfordia papilio stenoptera K. Yamazaki and Ueshima
status	subsp. nov.

Treatment

Hungerfordia papilio stenoptera K. Yamazaki and Ueshima View in CoL subsp. nov.

( Figs. 9O View FIGURE 9 , 28 View FIGURE 28 , 29J View FIGURE 29 )

Hungerfordia U: Rundell, 2008, 3403, fig. 3C.

Materials examined. Holotype. East of Li el Kim, northern coast of central part of Mecherchar island (Loc. Mc1- 1), Palau. Collected by R. U. and K. Y. on June 29, 2005. UMUTZ-MG-B0223 T . Paratypes. Mecherchar and its satellite islets: Loc. Mc1-1, 57 specimens, 29/VI/2005, UMUTZ-MG-B0223; Loc. Mc2-1, 6 specimens, 1/VII/ 2005, UMUTZ-MG-B0236; Loc. Mc4-1, 63 specimens, 9/VII/2006, UMUTZ-MG-B0334; Loc. Mc5-1, 1 specimen, 15/XI/2006, UMUTZ-MG-B0556; Loc. Mc5-2, 7 specimens, 16/XI/2006, UMUTZ-MG-B0583; Loc. Mc5-3, 52 specimens, 17/XI/2006, UMUTZ-MG-B0630; Loc. Mc6-1, 2 specimens, 23/X/2007, UMUTZ-MG- B0761; Loc. Mc6-2, 22 specimens, 25/X/2007, UMUTZ-MG-B0822; Loc. Mc6-3, 13 specimens, 25/X/2007, UMUTZ-MG-B0836; Loc. Mc6-4, 13 specimens, 25/X/2007, UMUTZ-MG-B0849; Loc. Mc6-5, 10 specimens, 26/X/2007, UMUTZ-MG-B0869; Loc. Mc8-1, 27 specimens, 26/II/2011, UMUTZ-MG-B1202; Loc. Mc8-2, 49

specimens, 28/II/2011, UMUTZ-MG-B1253; Loc. Mc8-3, 11 specimens, 28/II/2011, UMUTZ-MG-B1261; Loc. Mc8-4, 32 specimens, 28/II/2011, UMUTZ-MG-B1272; Loc. Mc8-5, 36 specimens, 28/II/2011, UMUTZ-MG- B1284; Loc. Mc3-1, 33 specimens, 28/VI/2005, UMUTZ-MG-B0193. Euidelchol: Loc. Ik3-1, 111 specimens, 29/ VI/2005, UMUTZ-MG-B0212; Loc. Ik6-1, 24 specimens, 25/X/2007, UMUTZ-MG-B0806; Loc. Ik8-2, 36 specimens, 26/II/2011, UMUTZ-MG-B1193.

Diagnosis. Shell generally similar to H. papilio papilio but differs from the nominal subspecies by the following features: axial ribs less synchronized with those on the previous whorls; wing-like projections of axial ribs on the last 2–3 whorls narrower than the nominal subspecies, clearly separated from those on the previous whorls, more strongly folded at the periphery; angular margin of the inner peristome more strongly protruded. Distribution restricted to Mecherchar and Euidelchol islands.

Description. Shell ( Figs. 28A–I View FIGURE 28 , 29J View FIGURE 29 ). Shell sinistral, large for Hungerfordia species , slender conical, last whorl widest when removing the protruded ribs and peristomes. Shell color semi-transparent throughout the whorls, upper whorls occasionally yellow-colored with the color becoming deeper towards the apex. Whorls 7–8, convex; last 1/16–1/8 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 wing-like ribs, internally without palatal plica except a low axial-crest caused by the constriction. Tuba 7/8 whorls. Protoconch 1+1/4 to 1.5 whorls, smooth on the apical whorl, weakly and finely punctated on the lower whorl. Apical septum absent. Axial ribs developed on the teleoconch, highly developed as wings on most whorls: ribs undeveloped on the first 1/4 whorls of the teleoconch; ribs on the following 1/4–1/3 whorls of initial teleoconch low, moderately or widely spaced, not folded; ribs on the subsequent 2–3 whorls (upper whorls higher than the antepenultimate whorl) widely and highly protruded as wings, not folded or very weakly folded at the periphery, very widely spaced at almost a constant interval of 7 ribs in a whorl, almost synchronized with those on the previous whorls, but occasionally with a few non-synchronized ribs; wing-like projections of the ribs very high, very wide, thin, fragile, arising at or slightly below the suture, almost flat, protruded upward, mostly overlapped with and attaching to those on the previous whorls, with fine and weak spiral sculptures on the outer surface; ribs on the penultimate and antepenultimate whorls also highly and widely protruded as wings, very widely spaced (8–11 ribs in a whorl), partially or hardly synchronized with those on the previous whorls, weakly folded at the periphery; wing-like projections of the ribs narrower than and clearly separated from those on the previous whorls, curved upward, rather stout, arising at short distance below or just below the suture, upper margin weakly folded at the periphery over the lower margin, protruded rather upward; ribs above the aperture (ribs on the last 1 to the last 3/4 whorls around the constriction) abruptly becoming very closely spaced and very low, without wing-like projection, fine; ribs on the last 3/4 whorls highly developed as wings again, very widely spaced; wing-like projections of the ribs arising at longer distance below the suture than those on upper whorls (near periphery of the whorl), protruded laterally or rather downward, upper margin more prominently folded or curled at the periphery over the lower margin. Spiral sculptures present on the teleoconch, fine, very weak, frequently reduced on lower whorls, rather prominent on the outer surface of the wing-like ribs, sinuous in high magnification. Interspace between the wing-like ribs almost smooth on most whorls, with weak growth wrinkles on lower whorls; upper growth wrinkles developed below the suture on the last 5/8 whorls, fine, very low; lower growth wrinkles occasionally present above the suture of the last whorl, very weak, short, almost vertical. Base convex, without basal keel. Axial protrusions of shell wall (along the ribs) strongly developed on the last 3/4 whorls, hidden by the wing-like projections, abapertural and adapertural sides equally wide and concave in umbilical view. Umbilicus clearly opened in most populations, but very narrow in a few populations, width of 4–9 % of the shell diameter (including the expanded ribs and outer peristome). Aperture hardly or slightly tilted downward against the coiling axis, hardly protruded; columellar axis within aperture almost vertical. Columellar tooth absent. Peristome double, expanded: outer peristome developed, widely expanded beyond the inner one at the palatal and basal sides, often with rounded palatal edge, weakly reflexed outward, smooth and polished on the inner surface; inner peristome pentagonal circular or oval, widely expanded, moderately protruded from the outer one, upper palatal (angular) margin more or less protruded forward in umbilical view and weakly depressed in front view, palatal margin frequently concave just below the angular protrusion in left lateral view, basal margin occasionally concave in umbilical view, parietal margin located below the middle level of the upper body whorl. Interspace between the inner and outer peristomes of moderate width, smooth on the outer surface; uppermost margin ascending onto the penultimate whorl toward the aperture in left lateral view; base expanded toward the aperture in left lateral view.

Dimensions. Shell height 4.8–6.2 mm, diameter 3.6–5.0 mm, suture width 1.9–2.6 mm, peristome height 1.5– 2.1 mm.

Operculum ( Figs. 28J View FIGURE 28 1 –J View FIGURE 1 4 View FIGURES 4–5 ). Operculum corneous, multispiral, circular, transparent, amber colored, thin, flat, slightly concave; outer surface smooth; inner surface with a low, weak, arcuate ridge near the columellar margin.

Penis. Penis absent.

Radula ( Fig. 9O View FIGURE 9 ). Radula of specialized type of taenioglossate; ribbon very long. Central tooth very large, with a very wide, large, and blunt central cusp, without lateral cup, 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. Inner marginal teeth narrower and shorter than the lateral teeth, with a large major cusp, with two slender inner cusps, with a reduced outer cup. Outer marginal teeth shorter than the inner marginals, with a large and blunt major cusp, with a slender inner cusp, without outer cusp.

Distribution and ecology. Endemic to Palau: Mecherchar and Euidelchol islands, and their satellite islets. The species inhabits vertical walls of large limestone rocks or cliffs, occasionally on limestone rubbles.

Remarks. H. papilio stenoptera differs from the nominal subspecies in the following points. First, H. papilio stenoptera has narrower wing-like projections of the ribs on the penultimate and antepenultimate whorls, which are clearly separated from those on the previous whorls ( Figs. 28A View FIGURE 28 1 View FIGURE 1 , 28D, 28G View FIGURE 28 3 View FIGURES 2–3 ). Whereas, the nominal subspecies has much wider wing-like projections on these whorls, which are overlapped with and attaching to those on the previous whorls ( Figs. 27A View FIGURE 27 1 View FIGURE 1 , 27D, 27G View FIGURE 27 3 View FIGURES 2–3 ). Second, the less preserved synchronization of the wing-like ribs is also diagnostic of this subspecies. In the nominal subspecies, wing-like ribs on all whorls except the last one are perfectly synchronized with those on the previous whorls ( Figs. 27A View FIGURE 27 3 View FIGURES 2–3 , 27D, 27G View FIGURE 27 1 View FIGURE 1 ). In contrast, in H. papilio stenoptera , non-synchronized ribs occasionally occur on the apical whorls, and are frequently found on the penultimate and antepenultimate whorls ( Figs. 28A View FIGURE 28 3 View FIGURES 2–3 , 28D, 28G View FIGURE 28 1 View FIGURE 1 ). Third, in H. papilio stenoptera , the wing-like projections of ribs are more strongly folded at the periphery than the nominal subspecies, particularly on the penultimate and antepenultimate whorls ( Figs. 27A View FIGURE 27 3 View FIGURES 2–3 , 27D View FIGURE 27 , 28A View FIGURE 28 3 View FIGURES 2–3 , 28D View FIGURE 28 ). Fourth, in H. papilio stenoptera , the angular margin of the inner peristome is more strongly protruded ( Figs. 27A View FIGURE 27 4 View FIGURES 4–5 , 28A View FIGURE 28 4 View FIGURES 4–5 ), and thus, the palatal margin is more strongly concave in left lateral view ( Figs. 27A View FIGURE 27 2 View FIGURES 2–3 , 28A View FIGURE 28 2 View FIGURES 2–3 ). Fifth, the shell size is generally smaller and the umbilicus tends to be narrower compared to the nominal subspecies.

Mecherchar and Euidelchol populations are almost fixed for the characteristic phenotype, although there are few populations showing intermediate or exceptional phenotypes.

Etymology. The subspecific name, derived from Greek stenos (= narrow) and pterus (= with wing), refers to the narrower wing-like ribs on the last two whorls than the nominal subspecies.