Landouria intha, Páll-Gergely & Hunyadi & Hausdorf, 2020

Páll-Gergely, Barna, Hunyadi, András & Hausdorf, Bernhard, 2020, A new species of Landouria Godwin-Austen, 1918 (Gastropoda: Stylommatophora: Camaenidae) from Myanmar, Raffles Bulletin of Zoology 68, pp. 379-386 : 380-383

Landouria intha , new species

( Figs. 2–4 )

Type material. Holotype (D: 19.4 mm, H: 6.8 mm) ( HNHM 104442 ), Myanmar, Shan State, Pinlaung centre, SSW ca. 29 km – Laneli Bridge, Nam Pam , right side of rd., near “War Lee Kwey Cave (Resurgence)”, 700 m a.s.l., 19.97547°N, 96.67076°E (locality codes: 2018/31 and 20181004C), coll. A. Hunyadi & J.U. Otani, 04 October 2018 . Paratype (juvenile shell and body in ethanol) ( HNHM 104443 ), same data as holotype ; Paratypes (9 empty shells) (HA) (D: 16.7–18.8 mm, H: 5.1–6.5 mm), same data as holotype.

Description of the shell ( Fig. 2A ). D: 16.7–19.4 mm, H: 5.1–6.8 mm. Colour light reddish brown. Shell depressed, dorsal side flat, consisting of 5.25–5.5 slightly convex whorls. Body whorl with strong, sharp keel, with slight furrow below and above keel. Protoconch ( Fig. 2B ) consisting of 1.75 whorls, almost smooth, with very fine radial ribbing and slight indication of spiral striation along the suture. Teleoconch roughly, irregularly wrinkled without any traces of spiral striation. Radial wrinkles with additional, scale-like, triangular periostracal folds (scales) ( Fig. 2C–E ). Aperture quadrangular due to the prominent keel, upper insertion of peristome slightly descending. Peristome lighter in colour than the rest of the shell, strongly expanded, slightly reflected, discontinuous; parietal callus only indicated by slight transparent calcareous layer. Umbilicus open, relatively wide, funnel-shaped, occupying ca. one third of the shell’s width.

Description of the genitalia ( Figs. 3 , 4 ). Atrium short. Penis very long, without penial caecum, with membranaceous sheath around very distal part of penis. Penis internally ( Fig. 4A ) with a few fine longitudinal folds that become slightly stronger towards penial verge. Penial verge ( Fig. 4B, C ) small, rather conical, slightly irregular, opens terminally. Epiphallus approximately as long as penis, internally also with weak longitudinal folds. Retractor muscle slender, inserts at the middle of epiphallus. Flagellum ( Fig. 4E ) very long, broadest at its base, with a few nodes at the basal part, and multiple horizontally arranged nodes at the terminal part. Vas deferens narrow and long. Vagina slightly longer than penis, internally with longitudinal, occasionally serrate folds ( Fig. 4D ). Peduncle of bursa copulatrix subdivided into a strongly thickened base, internally with elevated, irregular, longitudinal folds, and a slender, much longer proximal part; spermoviduct longer then vagina, albumen gland also very long, elongated.

Differential diagnosis. This new species differs from all Aegista , Landouria , and Plectotropis species described from Myanmar and India by the flat apical side, the wide umbilicus, and the relatively large, permanent periostracal folds covering the entire surface.

The most similar species is Plectotropis nutans Gude, 1914 (described in Gude, 1914a; Fig. 5 ) (material examined: 3 syntypes [ NHMUK 1906.3.3.68], Habiang, Garo Hills, Assam, coll. Godwin-Austen), which has a slightly elevated spire resulting in a low conical shape, a much narrower umbilicus, and no deciduous periostracal folds, but is finely spirally striated and irregularly, finely wrinkled .

Plectotropis akowtongensis ( Theobald, 1859) (material examined: 6 shells [NHMUK 1906.2.2.130], Pegu, Thyet Myo, coll. W.T. Blanford; 2 shells [NHMUK], Pegu; 5 shells [NHMUK 1909.3.15.24], Akoutong, Pegu; 1 shell, [NHMUK 1910.6.33.1921], Pegu; 1 shell [NHMUK 1903.7.1.394], Akoukthoung, on Irrawady, Pegu, coll. Godwin-Austen; 2 shells [NHMUK], Thayet Myo, Burmah, coll. Salisbury) is much smaller, paler in colour, has a low dome-shaped dorsal side and a narrower umbilicus, but is somewhat similar in sculpture. Namely, the shell surface is very finely scaly. Fine periostracal folds, which are nevertheless much smaller than those of the new species, are also present near the suture and the keel in fresh shells. Even in live collected specimens the folds were largely lost, indicating that these are not permanent in Plectotropis akowtongensis .

Aegista phayrei ( Theobald, 1859) (material examined: 4 shells [NHMUK 1906.2.2.274], Ava, Myaleit doung, coll. Godwin-Austen; 1 shell [NHMUK], Ava, Burmah, coll. Godwin-Austen; 6 shells [NHMUK], Ava, coll. H.F./W.F. Blanford) also has an elevated spire, much narrower umbilicus, and blunter keel, but its sculpture is roughly, irregularly covered by scale scars.

The Chinese and Japanese Plectotropis species (e.g., P. gerlachi ( Martens, 1881) , P. vulgivaga (Schmacker & O. Boettger, 1890)) are strikingly similar to the new species in terms of shell shape and sculpture. However, the Japanese/ Taiwanese species usually have prominent, long periostracal folds on the keel, whereas the new species is uniformly scaled on its entire surface.

Etymology. The specific epithet refers to the Intha people inhabiting the environment of the closely situated Inle lake. It is used as a noun in apposition.

Aegista oldhami ( Benson, 1859) (photos examined: 1 syntype [UMZC I_104645], Ava) is smaller and lighter in colour, ACKNOWLEDGEMENTS has a slightly elevated spire, blunter keel, and its dorsal side is finely scaly, while the ventral side is practically smooth. We are grateful to Jonathan Ablett (NHM) for granting access to the collection of the NHM, to Harold Taylor

Aegista tapeina ( Benson, 1836) (material examined: 2 shells (NHM) for providing photographs of Plectotropis nutans , [NHMUK], E. Frontier of Bengal; 2 adult + 2 juvenile shells and to Tom White (NHM) for providing photos of Aegista [NHMUK], Theria Ghat, coll. Godwin-Austen) has a slightly oldhami . We thank Jennifer Lauschke (Zoological Museum, elevated spire, a narrower umbilicus and a blunter keel than Hamburg) for performing DNA extraction and PCR. This the new species. Sculpture of the first sample is very finely study was supported by the MTA (Hungarian Academy of scaled, whereas that of the second sample is matte, finely Sciences) Premium Post Doctorate Research Program and the reticulated on the ventral side, and has some scales inside SYNTHESYS Project (GB-TAF-2523). We are also indebted the umbilicus and near the keel and suture. to The Biodiversity Heritage Library for the multitude of rare literature available to us (www.biodiversitylibrary.org).

Figures

Fig. 2. Holotype of Landouria intha, new species (HNHM 104442). Scale bar for A = 10 mm, B–E = 1 mm.

Fig. 3. Reproductive anatomy of the holotype of Landouria intha, new species (HNHM 104442). Abbreviations: a, atrium; ag, albumen gland; b, bursa of the bursa copulatrix; bb, base of the peduncle of bursa copulatrix; e, epiphallus; f, flagellum; p, penis; ps, penial sheath (indicated with grey shading); rm, retractor muscle; so, spermoviduct; v, vagina; vd, vas deferens. Asterisks indicate originally conjoined ends. Scale bar = 5 mm.

Fig. 4. Inner structure of genital organs of Landouria intha, new species (holotype, HNHM 104442). A, penis; B, penial papilla; C, penial papilla opened; D, vagina and base of bursa copulatrix; E, flagellum.

Fig. 5. Syntype of Plectotropis nutans Gude, 1914, NHMUK 1906.3.3.68. Scale bar = 10 mm.