Helix scalatella Möllendorff, 1888, subsequent designation by Pilsbry (1895) [in Pilsbry 1894–1895]).

Shell triangular, low conical or lenticular, body whorl keeled, whorls sometimes scalariform, body whorl (sometimes only the last quarter whorl, sometimes all whorls) with subsutural furrow dorsally; protoconch smooth or spirally striated, teleoconch usually spirally striated and irregularly wrinkled; aperture adnate to penultimate whorl with weak parietal callus or free from penultimate whorl with continuous aperture; apertural barriers 0–5; umbilicus very narrow to moderately narrow.

“in cacumine montis Licos insulae Cebu”.

Shell triangular, keeled, end of body whorl with slight subsutural furrow on the dorsal side, protoconch spirally striated, teleoconch roughly wrinkled and finely striated spirally; aperture with a single columellar tooth; aperture free from penultimate whorl.

Figure 1. 

Shells of Aulacospira Möllendorff, 1890. A Aulacospira triptycha Quadras & Möllendorff, 1895 (SMF 4611, syntype) B Aulacospira lens Páll-Gergely & Auffenberg sp. n. (paratype, UF 245505, uncleaned with original coating) C Aulacospira lens sp. n. (UF 245485, holotype) D Aulacospira hololoma (Möllendorff, 1887) (SMF 4608, lectotype) E Aulacospira mucronata (Möllendorff, 1887) (SMF 4609, lectotype) F Aulacospira krobyloides Páll-Gergely & Schilthuizen sp. n. (RMNH.MOL.340281, holotype). Scale bar: 3 mm.

H = 2.3–2.5, D = 3.1–3.4 (n = 3).

Philippinen: Mte. Licos, Cebu, coll. Möllendorff, SMF 4608 (lectotype, selected by Zilch [1984], H: 2.4 mm, D: 3.3 mm); same data, SMF 10701/4 paralectotypes; same data, coll. O Boettger ex coll. Möllendorff, SMF 63878/3 paralectotypes.

Cebu Id., leg. Univ. Alabama, TH Aldrich Coll., Ex: WF Webb (THA-3079), UF 112317 (4 shells).

This species is only known from the type locality on Cebu Island (Fig. 2).

Figure 2. 

Distribution of Aulacospira (circles) and Pseudostreptaxis (triangles) species. The black square on the upper map is enlarged below. 1: A. scalatella; 2: A. porrecta; 3: A. rhombostoma; 4: A. triptycha; 5: A. lens sp. n., 6: A. hololoma and A. mucronata; 7: A. mucronata; 8: A. krobyloides sp. n.; 9: P. azpeitiae; 10–11: P. harli sp. n. Question mark shows Catanduanes Island, which is the type locality of P. azpeitiae.

Palawan Province, El Nido Municipality, Pinagbuyutan island, 11.121N, 119.394E, sieved from litter under limestone cliff, 17 Mar 2018, M Schilthuizen leg., TxEx-PA0001-17, RMNH.MOL.340281 (holotype, H: 2.4 mm, D: 3.5 mm).

Shell flattened and keeled, all whorls with slight subsutural furrow on the dorsal side, protoconch smooth with slight spiral striation, teleoconch roughly wrinkled and finely spirally striated; aperture with indication of a columellar tooth; aperture adnate to penultimate whorl.

Shell depressed-conical (ca. 1.5 times as wide as high) with a strong keel in the middle of body whorl, and a very slightly indicated subsutural furrow between the keel and the suture; colour off-white, but fresh specimens will probably have a darker colour; entire shell consists of 4.5 whorls; protoconch elevated, consisting of ca. 1.25 whorls, finely granulose, with some spiral striation; teleoconch finely granulose, with some fine, irregular wrinkles and fine, dense spiral striae; aperture strongly oblique to shell axis, aperture shape suboval; peristome slightly expanded from parieto-palatal junction to parieto-columellar junction, additionally slightly thickened between keel and columella, peristome slightly expanded in direction of umbilicus, partly covering it; parietal callus appears as additional, rather strong lime layer on parietal part; columellar tooth only indicated on columella, blunt; no parietal or palatal teeth present; umbilicus very narrow, shows all whorls, ca. its half is covered by expanded peristome edge.

H = 2.4, D = 3.5 (holotype).

Aulacospira krobyloides sp. n. is most similar to A. lens sp. n., which is more depressed, has a wider umbilicus, lacks spiral striation on the teleoconch, and has a parietal tooth. Aulacospira hololoma has a higher conical shell, and its aperture is free from the preceding whorl. Aulacospira triptycha is larger, flatter, has a wider umbilicus, and well-developed columellar tooth and a small palatal denticle.

This species is only known from the type locality on Pinagbuyutan Island (Fig. 2).

This new species is named for its resemblance to members of the genus Krobylos Panha & Burch, 1999.

Panay Ids., Iloilo Prov., Carles Municipality, ca. 15.0 km E Carles, South Gigante Id., south shore, 75 m, 11°35'N, 123°20.5'E, 24 Apr 1992, K Auffenberg, et al. leg., KA-1039, UF 245485 (holotype, H: 2.0 mm, D: 3.5 mm); same data, UF 525638 (37 paratypes = juvenile/subadult shells); same locality, KA-1040, UF 245505 (7 paratypes = juvenile/subadult shells); same data, 9 paratypes in ethanol.

Shell strongly flattened and keeled, all whorls with slight subsutural furrow on the dorsal side, protoconch smooth with slight indication of spiral striation, teleoconch roughly wrinkled without spiral striation; aperture with a columellar and a parietal tooth; aperture adnate to penultimate whorl.

Shell strongly discoid (1.7–1.9 times as wide as high) with a strong peripheral keel, and a shallow subsutural furrow between the keel and the suture; colour light brownish-greyish with occasionally some purplish colouration; fresh shells with some sand or detritus attached to both dorsal and ventral surfaces, probably functioning as camouflage; shell consists of ca. 4 whorls; protoconch consisting of ca. 1.0 whorl, finely granulose, superficially smooth, with some very faint spiral striation; teleoconch finely granulose, with weak, irregular wrinkles, without spiral striae; aperture strongly oblique to shell axis, aperture shape suboval with palatal elongation due to keel; peristome sharp on the palatal portion above keel, slightly thickened and reflected between keel and columella, and slightly expanded toward umbilicus, partially covering it; parietal callus very weak, often transparent; columellar tooth low on the columella, well-developed, blunt; parietal lamella present only in holotype (all other shells are subadults), relatively long, low, slightly immersed from parietal callus; umbilicus narrow, showing all whorls, partially covered by expanded peristome.

H = 1.9–2.0, D = 3.5–3.6 (n = 2: the holotype and one large subadult shell).

Aulacospira lens sp. n. is similar to A. hololoma by the presence of a single columellar tooth, but differs from that species is being larger and much flatter. Aulacospira mucronata is similar to A. lens sp. n. in shape, but it differs from the new species by having a subsutural furrow on the dorsal side of the whorls, a comparatively smaller aperture, a wider umbilicus, and lacking any apertural barriers. Aulacospira triptycha has a larger and flatter, spirally striate shell, a wider umbilicus, has no parietal tooth, but possesses a small palatal denticle.

This species is only known from the type locality on South Gigante Island (Fig. 2). The snails were collected on shaded karst limestone.

The specific epithet lens (Latin lentil) refers to the shape of the new species. It is to be used as a noun in apposition.

“ad cacumina montis Licos et Uling insulae Cebu”.

Shell discoid and sharply keeled, body whorl (mainly the last half whorl) with slight subsutural furrow on the dorsal side, protoconch finely striated spirally, teleoconch roughly wrinkled and finely striated spirally; aperture without barriers, free from penultimate whorl.

H = 1.3–1.4, D = 3.1–3.3 (n = 3).

Types examined: Philippinen: Mte. Licos, Cebu, coll. Möllendorff, SMF 4609 (lectotype, selected by Zilch [1984], H: 1.4 mm, D: 3.2 mm); same data, coll. O Boettger ex coll. Möllendorff, SMF 63880/3 paralectotypes; same data, coll. Möllendorff, SMF 4671(?)/7 paralectotypes.

Cebu Id., Tuburan Municipality, leg. HG Lee, ex GD Robinson; WF Webb, UF 110445 (4 shells); Cebu Id., leg. Univ. Alabama, M Smith Coll (MS-8513), UF 112319 (2 shells); Cebu Id., leg. Univ. Alabama, TH Aldrich Coll., Ex: WF Webb (THA-3080), UF 112318 (5 shells).

This species is only known from the type locality on Cebu Island (Fig. 2).

“prope vicum Antipolo provinciae Manila”.

Shell flattened, and keeled, penultimate whorl elevated from body whorl resulting in a step-like appearance, body whorl with slight subsutural furrow on the dorsal side, protoconch spirally striated near teleoconch, teleoconch roughly wrinkled and finely striated spirally; aperture with four denticles (2 palatal, 1 parietal, 1 columellar), sometimes with an additional weak basal tooth; aperture free from penultimate whorl.

Figure 3. 

Shells of Aulacospira Möllendorff, 1890 species. A Aulacospira rhombostoma Quadras & Möllendorff, 1896 (SMF 4612, lectotype) B Aulacospira scalatella (Möllendorff, 1888) (SMF 4606, lectotype) C Aulacospira porrecta Quadras & Möllendorff, 1894 (SMF 4614, lectotype). Scale bar: 3 mm.

H = 1.6–1.8, D = 2.7–2.8 (n = 3).

Philippinen: Antipolo, Prov. Manila, Luzon, coll. Möllendorff, SMF 4606 (lectotype, selected by Zilch [1984], H: 1.8 mm, D: 2.8 mm); same data, SMF 4607/9 paralectotypes.

Luzon Id., Rizal Prov, mts of Bosoboso, leg. Univ Alabama, TH Aldrich Coll (THA-3081), UF 112322 (2 shells).

This species is known from two localities in Luzon island (Fig. 2).

“in insula Ilin prope Mindoro”.

Shell strongly flattened and keeled, body whorl with slight subsutural furrow on the dorsal side, protoconch spirally striated, teleoconch roughly wrinkled and finely striated spirally; aperture with four denticles (2 palatal, 1 parietal, 1 columellar); aperture free from penultimate whorl.

H = 1.5–1.6, D = 2.8–3.3 (n = 3).

Philippinen: Insel Ilin b. Mindoro, coll. Möllendorff, SMF 4614 (lectotype, selected by Zilch [1984], H: 1.6 mm, D: 3.3 mm); same data, SMF 4615/5 paralectotypes.

Mindoro Id., leg. Univ Alabama, TH Aldrich Coll, ex: WF Webb (THA-3083), UF 112320 (1 shell).

This species is only known from the type locality (Ilin Island, Fig. 2).

“in insula Tablas”.

Shell strongly flattened and keeled, body whorl with subsutural furrow on the dorsal side, protoconch smooth, teleoconch roughly wrinkled and finely striated spirally; aperture with a weak columellar and parietal tooth, and a palatal ridge corresponding to the furrow; aperture free from penultimate whorl.

H = 1.7–1.8, D = 3.2–3.5 (n = 3).

Philippinen, Tablas, coll. Möllendorff, SMF 4612 (lectotype, selected by Zilch [1984], H: 1.8 mm, D: 3.5 mm); same data, SMF 4613/7 paralectotypes.

Tablas Id., Looc, leg. Univ. Alabama, TH Aldrich Coll. (THA-3084), UF 112321 (4 shells).

This species is only known from the type locality on Tablas Island (Fig. 2).

“in monte Bathuan prope vicum Palanoc insulae Masbate”.

Shell discoid, strongly keeled, last half whorl with slight subsutural furrow on the dorsal side, protoconch smooth, teleoconch roughly wrinkled and finely striated spirally; aperture with a columellar and a palatal tooth; aperture adnate to penultimate whorl.

H = 1.8, D = 4.5 (n = 1, holotype with damaged apex).

Philippinen: Bathuan, Palanoc, Ins. Masbate, coll. Möllendorff, SMF 4611/1 syntype.

This species is only known from the type locality on Masbate Island. Palanoc is the former capital of Masbate at the mouth of the Lumbang River (12°21.5'N, 123°34.5'E, Fig. 2).

Palawan Province, Calamianes Islands, Coron Id., Kabudao Lake, NE shore, 40 m, 18 May 1987, Palawan Exp. leg., KA-520, UF 116981 (1 juvenile shell).

Helix (Aulacospira) Azpeitiae Hidalgo, 1890 by monotypy.

Shell globular, body whorl rounded or with smoothed peripheral angle, penultimate whorl rounded or narrowed or keeled (resulting in a streptaxoid shell shape); protoconch spirally striated, teleoconch with fine spiral striation and irregular growth wrinkles; aperture adnate to penultimate whorl, parietal callus weak, peristome almost discontinuous; apertural barriers 1–5; umbilicus narrow or relatively wide.

This genus has been monotypic so far. The type species, Pseudostreptaxis azpeitiae is characterized by a shell shape having distorted upper whorls reminiscent of those of Streptaxidae, and 4–5 apertural barriers. Pseudostreptaxis harli sp. n. differs conspicuously from P. azpeitiae by having a single parietal tooth and possessing a globular shell, but it often has a narrowed penultimate whorl similar to that of P. azpeitiae. Since the two species of Pseudostreptaxis differ considerably from each other, a modified diagnosis must be given. Due to the rounded body whorl this genus is treated as a full genus, as did to Schileyko (1998). Although this morphological difference might not seem to be sufficient for genus-level distinction, we rather use the most recent taxonomy.

“Isla Catanduanes”.

Shell streptaxoid (penultimate whorl keeled, rapidly descending toward aperture and oblique to shell axis; body whorl rather rounded, descending more slowly); protoconch with very weak (barely visible) spiral striation, teleoconch with rough wrinkles and some spiral striation; aperture with five teeth (1 parietal, 2 palatal, 1 basal that can be absent sometimes, 1 columellar).

Figure 4. 

Shells of Pseudostreptaxis Möllendorff, 1890 species. A Pseudostreptaxis azpeitiae (Hidalgo, 1890), SMF 63882 B Pseudostreptaxis harli sp. n., holotype (NHMW 113033) C–E Pseudostreptaxis harli sp. n., paratypes from the same sample (NHMW 113034). Scale bar: 3 mm.

Figure 5. 

Synoptic view of Aulacospira Möllendorff, 1890 and Pseudostreptaxis Möllendorff, 1890 species. A Pseudostreptaxis azpeitiae B Pseudostreptaxis harli sp. n. C Aulacospira triptycha D Aulacospira krobyloides sp. n. E Aulacospira hololoma F Aulacospira lens sp. n. G Aulacospira rhombostoma H Aulacospira scalatella I Aulacospira porrecta J Aulacospira mucronata. Scale bar: 3 mm.

Not examined.

Philippinen: Busuanga (Calamianes), Bintuan, coll. Möllendorff, SMF 63882/9; Palawan Province, Calamianes Ids., Busuanga Id., leg. Beal-Maltbie Coll., UF 240009 (3 shells); Palawan Province, Calamianes Ids., Busuanga Id., Penon de Bintuan, leg. Univ. Alabama, T.H. Aldrich Coll, ex: WF Webb (THA-3082), UF 112316 (2 shells).

The type locality of this species is Catanduanes Island, which is situated on the eastern edge of the Philippines. However, all other material of this species was collected on Busuanga Island (Calamianes) in the western part of the Philippine Islands. Möllendorff (1898) gives only Busuanga as the distribution without comment. A hypselostomatid species occurring on two islands nearly 500 km apart is highly unlikely, given that all other members of this family are narrow-range endemics. Furthermore, the newly described congeneric, P. harli sp. n. (see below), also occurs geographically near the Calamianes. Therefore, we conclude that the occurrence of P. azpeitiae on Catanduanes is probably erroneous, and this species only occurs on Busuanga Island.

Palawan Province, El Nido Municipality, Shimizu Island, Panaustard (?) leg. J Harl, 15 Feb 2009, NHMW 113033 (holotype); same data, NHMW 113034/3 photographed paratypes (Fig. 4C–E), HNHM 103477/5 paratypes; PGB/10 paratypes, SMF 351762/3 paratypes; REI/43 paratypes; Palawan Province, El Nido Municipality, Miniloc Island, 11.146N, 119.313E, sieved from litter underneath limestone cliff, leg. M Schilthuizen, 18 Mar 2018, TxEx-PA0003-45, RMNH.MOL.340315/30 paratypes, PGB/60 paratypes.

Shell globular, protoconch spirally striated, teleoconch roughly wrinkled and spirally striated; aperture with a single parietal tooth that sometimes consists of two tubercles; aperture adnate to penultimate whorl.

Shell globular (0.95–1.15 times as wide as high) with bulging whorls and deep suture; in some specimens penultimate whorl narrowed, somewhat similarly to that of Pseudostreptaxis azpeitiae; colour light brownish-greyish to dark purple; entire shell consists of 4–4.5 whorls; protoconch consisting of ca. 1.25 whorl, finely granulose and spirally striated; teleoconch finely granulose, with some fine, irregular wrinkles and with dense, hardly visible spiral striation; aperture oblique to shell axis, aperture rounded; peristome thickened and expanded, especially in the basal and columellar direction; parietal callus weak, appears as a lime layer on the penultimate whorl; parietal tooth (lamella) elevated, deeply situated, relatively long, in some specimens consisting of two tubercles, which might indicate that it is homologous with the parieto-angular lamella; no other apertural barriers present; umbilicus open but very narrow, showing only the last whorl, mostly covered by expanded peristome.

H = 2.6–3.0, D = 2.9–3.1 (n = 2).

Pseudostreptaxis azpeitiae has a keeled penultimate whorl resulting in a shell shape reminiscent of the Streptaxidae. Moreover, the new species has a single parietal tooth, while Pseudostreptaxis azpeitiae possesses 4–5 apertural barriers.

This new species is placed in Pseudostreptaxis because of the rounded body whorl, which is keeled in Aulacospira.

The shell of P. harli sp. n. is unusually “spherical”. To obtain a uniform linear distribution, the shell shape may be expressed as the angle obtained by taking the inverse tangent of the ratio D/H (Örstan 2018). The distribution of the shell shape angles (ε) thus obtained against the mean greater shell dimensions (GSD, the larger of the shell height or diameter) for 2134 pulmonate genera (Fig. 6) forms one major cluster of flat (ε > 50°) shells and at least three smaller clusters of tall (ε < 40°) shells. In addition, there is a diffuse cluster of approximately 30 roughly equiaxial and small genera within the approximate ranges of ε = 44°–49° and GSD = 1.5–5 mm (Fig. 6, arrow). The mean shell values (ε = 46°, GSD = 3.03 mm) for Pseudostreptaxis harli sp. n. place this species in the latter cluster. The genera in this cluster, being members of eight families, form a phylogenetically diverse group. The evolutionary convergence of these small genera on a similar shell shape suggests that they and any individual species that may be included in this cluster, including P. harli sp. n., share a unique biological trait that has enabled them to overcome the opposing selective forces that have prevented more species to evolve equiaxial shell shapes.

Figure 6. 

Kernel density distribution of shell shape angles (ε) against the mean greater shell dimensions (GSD) for 2134 pulmonate genera. The kernel density increases from blue through green and yellow to red colours. Arrow points at the diffuse cluster of approximately 30 roughly equiaxial genera within the approximate ranges of ε = 44°–49° and GSD = 1.5–5 mm and within which P. harli sp. n. (circle) is located.

This species is known from two adjacent tiny islands (Miniloc and Shimizu) on the northeastern coast of Palawan (Fig. 2).

This new species is named after Josef Harl, a friend of the first author, who first collected this new species and provided it for study.