Research Article |
Corresponding author: Barna Páll-Gergely ( pallgergely2@gmail.com ) Academic editor: Edmund Gittenberger
© 2016 Barna Páll-Gergely, Igor V. Muratov, Takahiro Asami.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Páll-Gergely B, Muratov IV, Asami T (2016) The family Plectopylidae (Gastropoda, Pulmonata) in Laos with the description of two new genera and a new species. ZooKeys 592: 1-26. https://doi.org/10.3897/zookeys.592.8118
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Previously only a single plectopylid species, Helix laomontana L. Pfeiffer, 1862 was reported from Laos. Here we erect Naggsia Páll-Gergely & Muratov, gen. n. for H. laomontana based on the description of its reproductive anatomy and radula. Another species, Hunyadiscus saurini Páll-Gergely, gen. & sp. n. is described from Northern Laos based on conchological data. Helix (Plectopylis) andersoni Blanford, 1869, which is known from the Burmese-Chinese border region, is also classified within Hunyadiscus Páll-Gergely, gen. n. A third species, Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, 2015 is reported from Laos for the first time. The new localities represent the westernmost sites of the genus Gudeodiscus. The reproductive anatomy of the latter species is described.
Taxonomy, anatomy, radula, protoconch, new genus, new species
Land snails of the family Plectopylidae are widely distributed in East Asia, from Nepal to southern Japan (
The single species reported from Laos to date was originally described as Helix laomontana L. Pfeiffer, 1862 (type locality: “Lao Mountains, Camboja”) and was classified in Chersaecia by
Shell whorls were counted according to Kerney and Cameron (1979: 13) (precision 0.25).
For the nomenclature of lamellae (vertical parietal folds) and plicae (horizontal parietal folds and palatal folds) see
Ethanol-preserved specimens were dissected under a Leica stereomicroscope, equipped with a photographic camera. In the descriptions of the reproductive system, we used the terms “proximal” and “distal” in relation to the apical portion of the reproductive tract i.e. the ovotestis.
Individual buccal masses were removed and soaked in 2 M KOH solution for 5 hours before extracting the radula, which was later preserved in 70% ethanol. Radulae and shells were directly observed without coating under a low vacuum SEM (Miniscope TM-1000, Hitachi High-Technologies, Tokyo).
NHM
OK
Collection Kenji Ohara, Nishinomiya Shell
PGB Collection Barna Páll-Gergely (Mosonmagyaróvár, Hungary)
RE Collection Reischütz (Horn, Austria)
WM Collection Wim J. M. Maassen (Echt, The Netherlands)
2013 Gudeodiscus Páll-Gergely, In: Páll-Gergely and Hunyadi, Archiv für Molluskenkunde 142(1): 4, 8.
Plectopylis phlyaria Mabille, 1887, by original designation.
2015 Gudeodiscus (Gudeodiscus), — Páll-Gergely et al., ZooKeys 473: 13.
2015a Gudeodiscus (Gudeodiscus) messageri raheemi, — Páll-Gergely et al., ZooKeys 473: 38–40, Figures 5D, 5E, 10A, 12R–V, 20, 28E, 29F–G, 31B, 35D–F.
11L06 Laos, Luang Prabang Province, ca. 18 km SE of Muang Xiang Ngeun, on the left side of Nam Khan, limestone, black soil in limestone pockets, clay, under rocks and logs in old forest, 455 m a.s.l., 19°40.931'N, 102°19.743'E, leg. A. Abdou & I.V. Muratov, 30.10.2006,
Shells of Plectopylidae species. A Naggsia laomontana (L. Pfeiffer, 1862) (syntype,
A single living specimen collected in Laos, was killed by drowning and was stored in 70 % ethanol. A part of the body was extracted from the shell and was examined anatomically. The inner parts of the genitalia, such as the gametolytic sac, the diverticulum and the spermoviduct could not be extracted.
The reproductive anatomy of Gudeodiscus messageri raheemi was figured in the original description (
Gudeodiscus (Gudeodiscus) messageri raheemi was described from Vietnam, where it inhabits the provinces Ninh Bình, Thanh Hóa, Sơn La, Hòa Bình and Nghệ An. The Laotian specimens agreed in shell morphology with the Vietnamese specimens. The new Laotian localities of Gudeodiscus messageri raheemi represent the westernmost record of the genus (Figure
This taxon inhabits primary or old secondary broad-leaved forests, in the humid microenvironments under leaves, logs, limestone rocks and in black soil accumulated inside limestone pockets. The live collected specimen co-occured with Garnieria mouhoti (L. Pfeiffer, 1862), a well-known species that is also associated with the moderate humidity of broad-leaved forests (Figure
Hunyadiscus saurini sp. n.
andersoni Blanford, 1869, saurini Páll-Gergely, sp. n.
Shell dextral, body whorl keeled or angulated; protoconch with spiral and radial lines, with the spirals being dominant; palatal plicae slightly sinuate; parietal wall with a single lamella and some additional plicae/denticles anteriorly and/or posteriorly. Internal anatomy unknown. See also Remarks.
Hunyadiscus gen. n. differs from all other plectopylid genera by the protoconch sculpture, which is characterized by both spiral and radial lines, the spirals being dominant. Moreover, all species of Gudeodiscus, Halongella and Naggsia gen. n. have a rounded body whorl, which is keeled in Hunyadiscus gen. n. The most similar genus to Hunyadiscus gen. n. is Sinicola, which also possess a keeled (shouldered) body whorl, and usually lacks the apertural fold. See also Table
Key characters of the shell and genitalia of plectopylid genera possessing ribbed embryonic whorls. One star: see
Genus | Coiling direction | Apertural fold | Body whorl | Epiphallus | Penial pockets | Protoconch |
---|---|---|---|---|---|---|
Endothyrella | sinistral or dextral | absent | rounded or keeled | present | whole penial wall | ribbed* |
Sinicola | dextral | absent (rarely present) | keeled | present | whole penial wall | ribbed |
Gudeodiscus | dextral | absent or present | rounded | present | apical part | ribbed |
Halongella | dextral | present | rounded | present | whole penial wall | ribbed** |
Hunyadiscus gen. n. | dextral | absent | keeled | unknown | unknown | spirally striated and ribbed |
Naggsia gen. n. | dextral | absent | rounded | absent | absent | ribbed, ribs are wavy, with extremely fine spiral striation |
eastern Sicradiscus | dextral | absent | keeled | present | whole penial wall | ribbed |
western Sicradiscus | dextral | present | rounded | present | apical part | ribbed |
The genus is dedicated to András Hunyadi, Hungarian malacologist and shell collector, who first called the attention of the first author on the necessity of revising the family Plectopylidae. The name Hunyadiscus is the combination of the family name Hunyadi and discus (Latin: disc), which refers to the shape of the shells.
One species (H. saurini sp. n.) inhabits southern part of Northern Laos (exact locality unknown), the other species (H. andersoni) lives in southern Kachin state (Myanmar), at the bordering Chinese region (Figure
Many plectopylid species belonging to the genera Endoplon, Endothyrella, Gudeodiscus, Halongella, Plectopylis, Sicradiscus possess two parietal lamellae (anterior and posterior). Other species, however, possess only a single one. In most cases it is possible to decide that the single lamella is homologous with either the anterior or the posterior lamella, because there are “remains” of the other lamella. For example, in some Gudeodiscus species (e.g. G. multispira [Möllendorff, 1883]), there are some small denticles in position of the anterior lamella, anterior to the well-developed, curved lamella. This indicates that the curved lamella is homologous with the posterior lamella. In contrast, in the genera Sicradiscus and Endothyrella, many species have small denticles on the posterior side of the single lamella. This suggests, that the single, well developed lamella is homologous with the anterior lamella (
1869 Helix (Plectopylis) andersoni Blanford, Proceedings of the Zoological Society of London: 448 [Bhamo in regno Avæ et Hoetone in Yunan].
1874 Helix andersoni, — Hanley and Theobald, Conchologia Indica…: 46, plate 112, figs 8–9 [Bhamo, and Hoetone in Yunan] (1870–1876).
1875 Helix (Plectopylis) andersoni, — Godwin-Austen, Proceedings of the Zoological Society of London: 612, Plate 74, fig. 9.
1885 Plectopylis Andersoni, — Möllendorff, Jahrbücher der Deutschen Malakozoologischen Gesellschaft, 12: 389 [“bei Bhamo in Oberbirma”, “»Hoitone« in der chinesischen Provinz Yünnan”].
1886 Plectopylis Andersoni, — Möllendorff, Jahrbücher der Deutschen Malakozoologischen Gesellschaft, 13: 188.
1887 Helix andersoni, — Tryon, Manual of Conchology. 2 (3): 161, Plate 34, fig. 71; Plate 35, figs 74–75 [Bhamo, in Ava; Hoetone, In Yunan].
1889 Helix (Plectopylis) Andersoni, — Tapparone Canefri, Annali del Museo Civico di Storia Naturale di Genova, 2a (7): 47 (=323). [“Catcin di Pun-Can, Cimfó, Monti Est di Bhamó”, “Bhamó, Hoetone”]
1896 Plectopylis andersoni, — Gude, Science Gossip, 3: 154, figs 17a–c [Near Bhamo and Ava, in Upper Burma and on the Yunnan-frontier].
1899a Plectopylis (Chersaecia) andersoni, — Gude, Science Gossip, 6: 148.
1899b Plectopylis (Chersaecia) andersoni, — Gude, Science Gossip, 6: 175.
1914 Plectopylis (Chersaecia) andersoni, — Gude, The Fauna of British India including Ceylon and Burma. Mollusca II. (Trochomorphidae – Janellidae), 2: 73, 114, figs 55a–c.
2013 Chersaecia andersoni, — Páll-Gergely and Hunyadi, Archiv für Molluskenkunde 142 (1): 7, figs 14–15.
According to Dance (1986) the collection of Blanford is deposited in the British Museum (now: Natural History Museum, London). In the type collection of the NHM we did not find syntypes, but there is a sample (
Yünan, Slg. Bosch, ex H. Rolle (1 juv.),
A very large, discoid, angulated species with elevated, sharp callus and spirally striated protoconch.
Shell flat, angulated, light brown or corneous; ventral side of the body whorl keeled around the moderately wide, very deep umbilicus; protoconch spirally striated, radial ribs are mostly visible on its first whorl only; teleoconch equally ornamented with fine ribbing and spiral striae, resulting in rough, irregular reticulated surface on the dorsal side; ventral side also reticulated, but much weaker than the dorsal surface; 7.5–8.5 slowly increasing whorls separated by shallow suture; near the sutures the riblets sometimes supported with fine folds of the periostracum; aperture rounded, with white, slightly expanded and thickened apertural rim; callus slightly elevated, sharp, slightly S-shaped and forms two canals upon junction with the lip.
The parietal side was examined in one specimen (
(in mm). D = 24.6–27.2, H = 10.9–11.4 (n = 2,
This species differs from large Chinese Gudeodiscus species (and Naggsia laomontana) by the keeled margin of the shells. It is much larger than all Sinicola species. The largest Sinicola species, S. fimbriosa (Martens, 1875) does not have a callus and has a stronger apertural margin.
The species is known from Northern Burma and Western Yunnan. Hoetone (Hutung Village) and Bhamo are located in Kachin Provinces, whereas Ava is in Mandalay Province (all in Burma/Myanmar). The Kakhyen Hills are situated on the Chinese (Yunnan) and Burmese (Kachin) border.
1953 Plectopylis laomontana, Saurin, Journal de Conchyliologie, 93 (4), 113.
Laos, Pa Hia (Ancienne province Tran Ninh), Coll. Saurin,
Shells of Plectopylidae species. A holotype of Hunyadiscus saurini Páll-Gergely sp. n. B Hunyadiscus andersoni (W. Blanford, 1869) (
Parietal (A, C, E, G) and palatal (B, D, F, G) plication of Plectopylidae species. A–B Hunyadiscus saurini Páll-Gergely sp. n. C–D Hunyadiscus andersoni (W.
A dextral, medium-sized or large species with a relatively sharp upper keel and a blunt lower keel on the body whorl. On the parietal wall there is a single oblique lamella with a horizontal plica below it.
The shell is yellowish or corneous (the type material consists mainly of weathered shells). The protoconch is very large, with regular riblets and spiral lines; the radial and spiral lines are approximately of the same strength. The 5.25–6 whorls are separated by a shallow suture. The umbilicus is wide but moderately deep. The body whorl has a prominent upper keel and a less conspicuous lower keel. The apertural margin is slightly thickened. The parietal callus is blunt, not well developed and is only clearly apparent in older specimens.
Three shells were opened. On the parietal wall there is a single curved lamella that is oblique, its upper end situated much more anteriorly than the lower end. A short, but thick vertical plica is situated below and anteriorly of the lamella. On the palatal wall there are six more-or-less parallel plicae, with some additional short plicae. The most prominent additional plica is situated above the posterior end of the last plica. The fifth plica is usually S-shaped.
(in mm). D= 16.3–21.3, H= 6.7–8.6. (n=4, shells from different samples).
Hunyadiscus saurini sp. n. is smaller than H. andersoni, its keel is situated higher (this results a more angular body whorl), has weaker parietal callus, a lower horizontal plica on the parietal wall which is absent in H. andersoni. Naggsia laomontana has a rounded body whorl and weaker spiral striation on its protoconch.
The species is named in honour of the French geologist and malacologist Edmond Saurin (1904–1977) who collected it.
Laos, Pa Hia (Ancienne province Tran Ninh).
This species is known only from Southern Laos.
This new species shows considerable diversity in terms of shell size. However, the other shell characters are stable within and between samples.
The village “Pa Hia” or “Pah Hia” is located 100 km south from Xieng-Khouang, the capital of Tran Ninh Province (see
Helix laomontana L. Pfeiffer, 1862.
Naggsia laomontana (L. Pfeiffer, 1862).
Shell flat, widely umbilicated, body whorl rounded; protoconch with dense, regular, slightly waved ribs with extremely fine spiral striation. Epiphallus absent, diverticulum and gametolytic sac are both very short, but diverticulum is still shorter than the gametolytic sac. Cusp of central tooth missing, only basal plate of central tooth present. Marginals bicuspid.
Naggsia gen. n. differs from the genera having ribbed embryonic whorls (Endothyrella, Gudeodiscus, Halongella, Sicradiscus, Sinicola) by the absence of an epiphallus and the presence of a very short diverticulum. Moreover, although the protoconch of Naggsia gen. n. is ribbed, the ribs (radial lines) are not straight, as in the other genera, but are somewhat wavy. Naggsia gen. n. differs from the genera without a ribbed protoconch (Chersaecia, Endoplon, Plectopylis) by the presence of regular, slightly waved ribs on the embryonic whorls. The latter genera are insufficiently known anatomically. Plectopylis bensoni Gude, 1914 (mentioned as P. achatina Pfeiffer, 1845) and P. cyclaspis Benson, 1859 have a well-developed epiphallus (
The new genus is dedicated to Fred Naggs (NHM) in acknowledgement of his help with our studies on the Plectopylidae.
Northern Laos (Figure
The anatomy of Naggsia laomontana is rather similar to that of Plectopylis in the short diverticulum and to Chersaecia in the absence of epiphallus. The shell characters, namely the ribbed protoconch and the reduced parietal plication is similar to the genera Endothyrella, Gudeodiscus, Halongella, Sicradiscus and Sinicola. The radula of Naggsia laomontana shows similarities with those of Gudeodiscus (Veludiscus), Halongella and Plectopylis (see
1862 Helix laomontana L. Pfeiffer, Proceedings of the Zoological Society of London, 272, Plate 36, figs 9–10 [Lao Mountains, Camboja].
1863 Helix laomontana, — L. Pfeiffer, Novitates Conchologicae 2: 216, Plate 57, figs 7–9.
1868 Helix laomontana, — L. Pfeiffer, Monographia Heliceorum Viventium...: 394.
1875b Helix (Plectopylis) laomontana, — Godwin-Austen, Proceedings of the Zoological Society of London: 612.
1887 Helix laomontana, — Tryon, Manual of Conchology, 2 (3): 160, plate 34, figs 60–62.
1897a Plectopylis laomontana, — Gude, Science Gossip, 3: 245, figs 36a–c.
1899a Plectopylis (Chersaecia) laomontana, — Gude, Science Gossip, 6: 148.
1899b Plectopylis (Chersaecia) laomontana, — Gude, Science Gossip, 6: 175.
1914 Plectopylis (Chersaecia) laomontana, — Gude, The Fauna of British India including Ceylon and Burma. Mollusca.−II. (Trochomorphidae-Janellidae): 73.
1920 Plectopylis laomontana, — Gude, Proceedings of the Malacological Society of London, 14: 62, fig. 1.
2013 Chersaecia laomontana, — Páll-Gergely and Hunyadi, Archiv für Molluskenkunde 142 (1): 7–8.
Cambodia,
Laos, Luang Prabang (alte Schau-slg.),
Laos, Luang Prabang Province, Ban Pak Ou, Nam Wu (opposite side of Ban Pak Ou), 364 m 20°03.48276'N, 102°12.79912'E, leg. Ohara, K. 13.10.2006., PGB/5; Laos, Tad Kuangsi Waterfall, about 20 km SW of Luang Prabang, 19°43'02.97”N 101°59'38.68”E., leg. Reischütz, A., February 2010., RE/3; Laos, Tad Kuangsi Waterfall, about 20 km SW of Luang Prabang, 19°43'02.97”N 101°59'38.68”E, leg. Theisl, T. April 2009., RE/3+2 juv.; Laos, Luang Prabang Province, Tad Kuangsi Xi (Waterfall), 466 m, 19°44.96071'N, 101°59.49286'E, leg. Ohara, K. 14.10.2006., PGB/1; 16L06 Laos, Luang Prabang Province, ca. 7 km S of Luang Prabang, Near Tad Thong waterfall, 431 m a.s.l., 19°50.064'N, 102°07.755'E, leg. A. Abdou, I.V. Muratov, 3.11.2006.,
A dextral, medium-sized or large species with a rounded body whorl, and no apertural fold. On the parietal wall there is a single curved lamella.
The yellowish, sometimes pink or light brown shell is dextral, almost flat with the apex slightly elevated. The 5.5–6 whorls are separated by a moderately deep suture. The protoconch is very densely, regularly ribbed, with extremely fine spiral lines across the ribs. The teleoconch is irregularly ribbed; the space between the ribs is greater than on the protoconch. The lip is only slightly thickened and reflexed. There is an elevated, but blunt parietal callus, which has two shallow channels at the meeting point with the parietal part of the lip.
Four specimens were opened. On the parietal wall there is a single curved lamella without additional plicae. On the palatal wall there are seven horizontal plicae. The first, (situated near the suture) is short, undivided, not inclined, sometimes having a short denticle slightly lower than its posterior end. The second plica is slightly indented in place opposing the parietal curved lamella just before it becomes dichotomously bifurcated posteriorly, with its lower posterior arm slightly inclined away from the suture. The third, fourth and fifth exhibit an increasing tendency to be divided opposing the parietal lamella and inclined posteriorly away from the suture. The sixth is strongly, equally divided, having both parts equally inclined posteriorly away from the suture. The last one, unequally divided, consists of a long, not inclined anterior part and short, inclined posterior part.
Naggsia laomontana resembles Gudeodiscus species in having the single parietal lamella, rounded body whorl and densely ribbed protoconch. The protoconch of N. laomontana however reveals a unique surface structure, the riblets are comprised of slight waves that do not stand as regularly as those of Gudeodiscus. Gudeodiscus species that usually have a somewhat elevated spire, more whorls, two horizontal plicae in front of the parietal lamella, and simple (undivided) palatal plicae.
(in mm). D= 28.3–32, H= 8.8–9.1 (n=3, syntypes); D= 18.6–21, H= 6.4–7.5 (n=5, specimens from Laos).
(Figs
Penis long, its distal part is more slender than the proximal part, internally with 5–6 longitudinal folds aligned next to each other; only one of the folds reach the proximal end of the penis, the others are shorter; the penial wall (outside of the folded area) is wrinkled; the wrinkles are stronger near the distal end of the penis; many small, flat, lenticular calcareous granules were found in the penis lumen; epiphallic differentiation was not detected; retractor muscle slightly thinner than penis, shorter than it and connected to the apical end of penis; vagina shorter than half of penis; vas deferens has thick coiled portion just after coming out of spermoviduct, connects to vaginal wall and forms part of penial wall, reaching the middle of the proximal part of penis; diverticulum short, oval, gametolytic sac with relatively thick, cylindrical stalk and thickened, rather quadrangular sac; there were five, well-developed embryos in the uterus.
Photo of the reproductive anatomy of Naggsia laomontana (L. Pfeiffer, 1862), 16L06, spec.2. Abbreviations: Ag: albumin gland; D: diverticulum; E: embryo in the uterus (one out of five); Gs: gametolytic sac; Hd: hermaphroditic duct; P: penis; Rm: retractor muscle; So: spermoviduct; V: vagina with vas deferens alongside; Vd: coiled portion of vas deferens. Asterix indicates the place until where vas deferens could be traced back. Scale represents 5 mm.
Inner walls of reproductive organs of Plectopylidae. A–C Naggsia laomontana (L. Pfeiffer, 1862) (same specimen as on Fig.
(Figure
The species was described from “Lao Mountains, Camboja”. We have seen material with more detailed geographical data only from the central part of Northern Laos (around Luang Prabang). In the collection of the Natural History Museum London, a single shell of Ch. laomontana is present with the locality “China” (
This species can be found in primary or old secondary broad-leaved forests, but it inhabits some peculiar habitats as well. It can survive droughts as well as periodical floods and can be found in large numbers near waterfalls (Kuang Si waterfall, for example, is one very popular collecting spot) (Figure
Parietal plication of Plectopylidae species (diagrammatic figures). A Hunyadiscus saurini sp. n. B–E main character states of Endothyrella, Gudeodiscus, Halongella, Sicradiscus and Sinicola (mainly after
We are grateful for Pongrat Dumrongrojwattana for donating Gudeodiscus messageri raheemi shells for study. Alexander Reischütz gave us digitalized Laotian maps; Kenji Ohara provided shell material; Ronald Janssen (
This study was supported by scholarships from Japan Student Services Organization and Mitsubishi Corporation to B. Páll-Gergely and Grants-in-Aid for Scientific Research (KAKENHI) from Japan Society for the Promotion of Science to T. Asami. Barna Páll-Gergely is currently an International Research Fellow of the Japan Society for the Promotion of Science. We are indebted to The Biodiversity Heritage Library for the multitude of rare literature made available to us (www.biodiversitylibrary.org).