Oospira gouldiana (Pfeiffer, 1857)

Man, Nem Sian, Lwin, Ngwe, Sutcharit, Chirasak & Panha, Somsak, 2023, Further notes on the taxonomy of the land snail family Clausiliidae Gray, 1855 (Stylommatophora, Helicina) from Myanmar with description of two new species, ZooKeys 1160, pp. 1-59 : 1

8 Oospira gouldiana (Pfeiffer, 1857)

Figs 3E , 11 , 13A-D , 15C , 18J

Clausilia gouldiana Pfeiffer, 1857: 259. Type locality: "Mergui imperii Birmani" [Myeik Islands, Tanintharyi Region, Myanmar]. Pfeiffer 1860: 123, pl. 34, figs 18-20. Pfeiffer 1868: 409. Stoliczka 1872: 208. Hanley and Theobald 1874: 48, pl. 118, figs 2, 3. Sowerby 1875: Clausilia pl. 16, species 148.

Clausilia (Phaedusa) gouldiana - Blanford 1872: 203, pl. 9, fig. 10.

Clausilia [ Phaedusa (Pseudonenia) ] Phaedusa gouldiana - Boettger 1878: 54. Pfeiffer and Clessin 1881: 391. Gude 1914: 314-316, fig. 108.

Oospira (Oospira) gouldiana - Nordsieck 2002b: 86. Nordsieck 2007: 23.

Oospira gouldiana - Szekeres et al. 2021a: 171, fig. 6d-f. Szekeres et al. 2021b: 41.

Materials examined.

Bardai Mountain, Hpa-an Township, Hpa-an District , Kayin State , Myanmar (16°59'10.4"N, 97°42'19.8"E): CUMZ 13048 (25 specimens in ethanol, Fig. 11A-C ). Kaw Ka Thaung Cave , Hpa-an Township , Hpa-an District , Kayin State, Myanmar (16°49'40.4"N, 97°42'31.0"E): CUMZ 13049 (23 specimens in ethanol, Fig. 11D ). Lun Nga Mountain , Hpa-an Township , Hpa-an District , Kayin State, Myanmar (16°44'53.2"N, 97°47'09.5"E): CUMZ 13050 (18 specimen in ethanol). Sadhdan Cave , Hpa-an Township , Hpa-District, Kayin State, Myanmar (16°44'23.4"N, 97°43'04.2"E): CUMZ 13051 (2 incomplete shells). Taung Lay Cave , Hpa-an Township , Hpa-an District , Kayin State, Myanmar (17°11'40.3"N, 97°37'47.0"E): CUMZ 13052 (30 shells; Fig. 11E ). Waiponla Mountain , Hpa-an Township , Hpa-an District , Kayin State, Myanmar (16°56'7.4"N, 97°42'56.8"E): CUMZ 13053 (2 incomplete shells, Fig. 11F ), CUMZ 13054 (2 specimens in ethanol, lost apical whorls). Rathye Pyan Cave , Hpa-an Twonship, Hpa-an District , Kayin State, Myanmar (16°50'6.2"N, 97°34'14.5"E): CUMZ 13055 (1 incomplete shell) .

Description.

Shell fusiform, translucent, brownish to reddish pink, and 3-4 white apical whorls; spire regularly attenuated. Shell surface finely striated to nearly smooth surface; suture impressed and distinct. Whorls 10-12 convex, regularly growing or sometimes rapidly growing after antepenultimate whorl and attenuated to apex. Aperture pear-shaped, basis broader and narrowing towards parietal sinus; peristome slightly protruded, thickened, expanded, and indistinctly doubled. Superior lamella developed, continuous with spiralis and slightly low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, five or six: first plica strong and longest; following plicae short, more or less parallel; fourth or fifth plica longer than middle plicae. Clausilium plate lateral side and narrow.

Genitalia (n = 5). Atrium (at) short and slender; penis (p) long, slender, and shortly narrower at transition to epiphallus. Epiphallus (ep) slender, ca. same length as penis, slightly smaller diameter, and broadest at middle. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) thin and shortly bounded at penis (Fig. 13A ). Internal sculpture of penis with smooth surfaces and five or six thin longitudinal folds (Fig. 13B ). Internal sculpture of epiphallus with irregular corrugated pattern (Fig. 13D ) and sometimes with distinct irregular transverse fold and papillae arranged in oblique rows.

Vagina (v) thick, cylindrical, and almost half of free oviduct (fo) length. Distal part of pedunculus (dpb) large and middle part broadest; diverticulum (db) slender, very long, ca. same length as distal part and proximal part of pedunculus; proximal part of pedunculus (ppb) slender, nearly same length as (dpb), and bursa copulatrix (bb) ovoid (Fig. 13A ).

Radula. Each row contains ≥ 39 teeth with half-row formula: central-(lateral)-marginal teeth (1-(11-12)-19). Central tooth tricuspid with large and triangular mesocone, and ectocones very small and pointed tips. Lateral teeth bicuspid: endocone large and triangular; ectocone very small and pointed tip. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 11 or 12: endocone small located near the tip; mesocone large and dull to blunt tip; ectocone with triangular shape, pointed tip and located near the base (Fig. 15C ).

Distribution.

Oospira gouldiana is the most abundant species of the genus in Myanmar, occurring mainly in the south-eastern part of the country. This species was abundant at seven limestone outcrops in Kayin State (Fig. 1 , Table 1 ). It was recorded from Bago, Kayin, Mon, and Tanintharyi in Myanmar, and the distribution was later expanded to include parts of Thailand ( Gude 1914; Szekeres et al. 2021a, b).

Remarks.

Oospira gouldiana specimens from Taung Lay Cave are quite similar to O. malaisei from Kachin State in terms of shell form. But O. malaisei (Fig. 17C ) shows a more vertical and broader aperture, reflected peristome, closely and rapidly attenuated apical whorls, and inferior lamella more straight ascending at peristome. In contrast, Taung Lay Cave specimens have an oblique and rounded aperture, less reflected peristome, regularly attenuated whitish apical whorls and inferior lamella more spirally ending at peristome. Anatomically, O. malaisei possesses an epiphallus of ~ 1/2 the penis length, while in O. gouldiana epiphallus and penis have almost equal lengths (see Nordsieck 1973: fig. 26).

Oospira gouldiana also shares a similar shell morphology with O. insignis exhibiting a regularly attenuated spire with whitish apical whorls, palatal plicae five, and a broad pear-shaped aperture. Nevertheless, O. gouldiana has a more attenuated spire, more parallel palatal plicae, aperture more vertical, and less glossy than O. insignis . In addition, this species can easily be separated from O. shanensis by its pale color, shorter and oblique palatal plicae, inferior lamella more spirally and closely ascending from spiralis and superior lamella. Oospira penangensis differs from this species by its less ventricose, narrower, and more vertical subquadrate aperture, inferior lamella ending straight at peristome and weaker superior lamella from apertural view.

Oospira gouldiana is highly variable in terms of shell color and shape. The typical form was found in the Bardai and Kaw Ka Thaung populations, showing a yellowish to pinkish color with a regular fusiform shape (Fig. 11A, D ), while the Taung Lay population have a slenderer shell and the Waiponla population have a more bulging shell (Fig. 11E, F ). In addition, the arrangement of palatal plicae shows much variation among the populations. For instance, the Bardai population has irregularly or obliquely arranged plicae (nearly vertical), Kaw Ka Thaung population has parallelly arranged plicae, while the Waiponla and Lun Nga populations have very weak and short parallelly arranged palatal plicae. Furthermore, a very short plica (dot-like) located near the anteriormost palatal plicae next to subcolumellaris is also observed in the Bardai population.

Except for the Sadhdan, Taung Lay, and Rathye Pyan populations, for which genitalia could not be examined, the remaining populations are similar in external genital morphology, with only slightly differing thickness of the longitudinal folds of the internal sculpture of the penis being observed. However, these four populations inhabit a very small geographical area, hence we attribute this minor difference to morphological variation.

Figures

Figure 1. Approximate collecting localities of the Phaedusa species (triangles) and Oospira species (circles) from Myanmar examined in this study. The numbers correspond to localities listed in Table 1.

Figure 3. Living snails A Phaedusa shanica from Pyinyaung Village, Mandalay Region (SH ~ 14 mm) B Oospira philippiana from Kayon Cave, Mon State (SH ~ 22 mm) C Oospira bulbus from Sanbel Cave, Mon State (SH ~ 19 mm) D Oospira ovata from Pathein Mountain, Mon State (SH ~ 16 mm) E Oospira gouldiana from Kaw Ka Thuang Cave, Kayin State (SH ~ 26 mm) F Oospira shanensis from Nanthe Cave, Shan State (SH ~ 25 mm).

Figure 11. Shell and clausilial apparatus of Oospira gouldiana A-C specimen CUMZ 13048 from Bardai Mountain, Kayin State A typical pinkish shell form B clausilial apparatus C not fully adult shell D yellowish shell form, specimen CUMZ 13049 from Kaw Ka Thaung Cave, Kayin State E slender shell form, specimen CUMZ 13052 from Taung Lay Cave, Kayin State F ovate shell form, specimen CUMZ 13053 from Waiponla Mountain, Kayin State. White arrow indicates principalis.

Figure 13. Genital anatomy of A-D Oospira gouldiana, specimen CUMZ 13049 A whole reproductive system B internal sculpture of penis C transition from penis to epiphallus D internal sculpture of epiphallus and E-H Oospira andersoniana, specimen CUMZ 13057 E whole reproductive system F overview of internal sculpture of penis and epiphallus G internal sculpture of penis H internal sculpture of epiphallus. Yellow arrows indicate approximate transitional position from penis to epiphallus.

Figure 15. Radula morphology A Oospira philippiana, specimen CUMZ 13039 B Oospira ovata, specimen CUMZ 13044 C Oospira gouldiana, specimen CUMZ 13049 D Oospira andersoniana CUMZ 13057 E Oospira shanensis, specimen CUMZ 13061. Blue color indicates central teeth row; yellow color indicates the transition from lateral to marginal teeth. ' C' indicates central tooth.

Figure 17. Shell of A Oospira decollata, paratype ZISP from West Burma, near Pakoku on Mount Victoria. 2200 m a. s. l. B Oospira insignis, lectotype USNM 117120 from Tavoy, Burmah C Oospira malaisei, holotype SMNH 3014 from NO-Birma: Pungkataung ca. 3000 ft. and D Oospira vespa, lectotype MCZ 169455 from Tavoy, British Burma. Photo: A Persson, SMNH (C).

Figure 18. Synoptic view of the clausiliid species recorded from Myanmar A Indonenia admirabilis, holotype NHMUK 20200185 B Oospira andersoniana, specimen CUMZ 13054 C Oospira arakana, lectotype NHMUK 1888.12.4.1037 D Cylindrophaedusa bacillum, specimen NHMUK 1906.2.2.345 E Oospira bulbus, possible syntype NHMUK 1903.7.1.1278 F Phaedusa burmanica, holotype NHMUK 1888.12.4.1058 G Oospira decollata, paratype ZISP H Indonenia excellens, specimen NHMUK 20200189 I Oospira fusiformis, holotype NHMUK 1906.2.2.380 J Oospira gouldiana, lectotype NHMUK 196548 K Oospira gracilior, lectotype NHMUK 1907.12.30.243 L Oospira insignis, lectotype USNM 117120 M Phaedusa kazueae, holotype NHMUK 20200187 N Phaedusa lemani (after Gude, 1914: fig. 107) O Oospira limborgi, holotype NHMUK 1903.7.1.1266, and P Oospira luneainopsis sp. nov., holotype CUMZ 13062.