FIRST RECORD AND DESCRIPTION OF A NEW SCABRINA SPECIES (GASTROPODA: CYCLOPHORIDAE) FROM PENINSULAR MALAYSIA

a bstract : A new species Scabrina belang from the limestone hills of north-western Peninsular Malaysia is described. This operculated land snail of the family Cyclophoridae differs from its nearest congeners S. calyx and S. inglisianus in a combination of characters namely, a notched inner peristome, a wing-like extension at the outer peristome at the parieto-palatal region and a flatter shell. This is the first record of the genus Scabrina in Peninsular Malaysia, extending the known range of the genus 1,000 km southwards.


INTRODUCTION
The genus Scabrina Blanford, 1863 has a widely umbilicated and discoid to almost discoid shell typical of some medium-sized cyclophorid genera in Southeast Asia (KobElt 1902(KobElt , hirano et al. 2019(KobElt , sutcharit et al. 2019. However, it can be distinguished from these genera by a combination of the following characters: a thick, rough and hirsute periostracum and a thin proteinaceous operculum with raised edges and spirally coiled lamella (bEnson 1857, blanFord 1863, KobElt 1902, GudE 1921, hirano et al. 2019. nEvill (1878) designated Cyclophorus pinnulifer Benson, 1857 from Teria Ghat, India, as the type species for the genus Scabrina.
Here, we describe a new species, Scabrina belang, representing the first record of this genus in Peninsular Malaysia, 1,000 km south of the nearest known record of Scabrina.

MATERIAL AND METHODS
The material examined was obtained from leaf litter collected in limestone karst forests during mal- and Batu Kurau (State of Perak) in Malaysia in 2010, 2011 and 2016. The litter was air dried before mollusc specimens were extracted (liEw et al. 2008, Foon et al. 2017). The material is deposited in the BORNEENSIS collection (BOR/MOL), Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah. Additional material from the second author's collection (ME) was also examined. To ensure unambiguous reference to the localities of the examined material of S. belang, we provide the unique code numbers, names and coordinates of limestone outcrops derived from the Malaysian limestone karst database, Mykarst 2.0 (liEw et al. 2021a(liEw et al. , 2021b(liEw et al. , 2021c. To map all the currently recognised Scabrina species (Fig. 1), we consulted blanFord (1864), MöllEndorFF (1884, 1885), GrEdlEr (1887), hoanG et al. (2018, 2020), do et al. (2020, and MolluscabasE (2022) as well as all other literature mentioned in this study.
The study is based on shell characters only, as all the specimens were air dried and no live animals were preserved in ethanol due to the sample processing method. To illustrate the range of shell size variation, the holotype and four paratypes of S. belang were photographed with a Leica DFC495 Digital Microscope Camera mounted on a Leica M205C microscope (Figs 2-6). We also showed fresh specimens without (Figs 3,5,6,7) and with periostracum (Figs 2,4,8) to illustrate their differences. The operculum of a paratype was figured . To illustrate the differences in peristomal structures, especially at the parieto-palatal area, the peristome of S. belang types was compared with the peristome of the types of its geographically nearest congeners S. calyx (Benson, 1856) andS. inglisianus (Stoliczka, 1871) (Figs 13-21).
Measurements of shell height (SH), shell width (SW), aperture height (AH) and aperture width (AW), umbilical width (UW) and number of whorls (NOW) were taken from 41 specimens of the new species (1 holotype and 40 paratypes), following the methods of vErMEulEn & whittEn (1998). The ratios of shell height to shell width (SH/SW), umbilical width to shell width (UW/SW) and shell width to number of whorls (SW/NOW) were also calculated to quantify the shell and umbilicus shape, respectively. We also measured the types of the nearest congeners S. calyx and S. inglisianus based on photographs in sutcharit et al. (2019) and included the measurements from stoliczKa (1871). These measurements are presented in Table 1.    (1887) and KobElt (1902) are sufficient for comparative purposes. The type photographs and description of S. thaitieni Thach, 2021 was also examined and the species is considered not to be a member of the genus Scabrina (see Remarks). Description. Shell discoid with a slightly raised spire, rather solid, opaque. Upon removal of periostracum, shell colour yellowish or reddish with irregular brown radial markings on the dorsal whorl surface and occasionally the ventral whorl surface, the brown markings may sometimes be vaguely outlined or developed into zig-zag patterns at the peripheral zone. Surface shiny when periostracum is removed. Spire slightly raised, almost flat. Apex somewhat acute, whorls convex. Suture deep, channelled, punctate with inconspicuous pits. Periostracum thick, yellowish-brown, with very fine radial folds along where the growth lines predominate, short hairs line both sides of the sutural channel, very fine spiral striations on the wall of the ultimate and penultimate whorls in the umbilical area. Protoconch smooth, of one whorl. Teleoconch with fine radial growth lines predominating. Spiral sculpture absent. Aperture circular. Peristome double, the inner one not reflected, its rim slightly protruding from the outer one; the outer peristome expanded, concave. Parieto-palatal area of the inner peristome developed into a notch near suture, the outer peristome slightly expanded near suture, folded into a wing-like structure of variable degree of extension, sometimes slightly reflected. Umbilicus open, very wide. Operculum proteinaceous, translucent brown, flat, flexible; its exterior with seven whorls, surface raised at periphery, flattened at nucleus; interior smooth, with a single cen-tral nipple. Dimensions. Shell height 4.11-7.38 mm; shell width 9.52-14.14 mm; shell height to shell width ratio 0.43-0.55; number of whorls 4-5; aperture height 2.63-4.01 mm; aperture width 2.69-5.05 mm; umbilical width 3.51-5.75 mm; umbilical width to shell width ratio 0.31-0.43. Ecology. S. belang inhabits leaf litter in limestone outcrop forests. Cross diagnosis. The characters of the widely umbilicated shell, the thick hirsute periostracum and the proteinaceous operculum with spiral lamellae are shared by S. belang and its congeners. The species of Scabrina geographically nearest to S. belang are S. calyx and S. inglisianus (Fig. 1). S. belang differs most distinctly from S. calyx and S. inglisianus in the peristomal structures of the parieto-palatal area (Figs 13-21). The character of the outer peristome with the wing-like extension is shared by S. belang and S. calyx but S. belang has an inner peristome with a notch whereas S. calyx has a simple and straight inner peristome. The parieto-palatal area of S. belang and S. inglisianus are both characterised by the notch in the inner peristome but the outer peristome in S. belang has a wing-like extension while S. inglisianus has a simple outer peristome. The wing-like extension of S. belang is consistently present in mature specimens albeit with some intraspecific variation in the degree of extension. The variation in shell height, shell width, number of whorls and umbilical width overlap between S. belang, S. inglisianus and S. calyx and shows no clear differentiation (Table 1). However, S. belang has a flatter shell (slightly smaller shell height to shell width ratio) compared to S. calyx and S. inglisianus (Table 1). S. belang has less rapidly expanding whorls (smaller shell height to number of whorls ratio) compared to S. calyx (Table 1).

SYSTEMATIC PART
Compared with Southeast Asian species further afield, S. belang resembles S. hispidula (Blanford, 1863) in having an almost flat spire and a double per- istome but differs from S. hispidula in the absence of strong spiral striations on the whorls and in the presence of the notch in the parieto-palatal region of the inner peristome as well as in the wing-like extension of the outer peristome. The variation in shell dimensions of S. belang overlaps with that of S. hispidula (shell height 7 mm, shell width 12-14 mm, aperture width 5 mm). S. belang resembles S. basisulcata in having an almost flat spire, a double peristome and a wing-like extension in the parieto-palatal region of the outer peristome, but differs from it in the presence of the notch in the parieto-palatal region of the inner peristome. S. belang has a smaller shell and aperture compared to S. basisulcata (shell height 9 mm, shell width 13-16 mm, aperture width 4 mm).
S. belang resembles S. patera in having an almost flat spire but S. patera differs in possessing a simple peristome with no wing-like extension of the outer peristome and no notch in the inner peristome at the parieto-palatal area as well as in the presence of periostracal hairs at the periphery. The shell of S. belang is larger compared to S. patera (shell height 2.5 mm, shell width 8-10 mm). The periostracal hairs of S. belang are located at the suture whereas those of S. laciniata are located at the periphery. Both S. belang and S. laciniata have a double peristome but differ in the parieto-palatal area where S. belang has an inner peristome with a notch and an outer peristome with a wing-like extension near the suture while S. laciniata has a simple peristome with no extensions or notches. The shell of S. belang is smaller than that of S. laciniata (shell height 8 mm, shell width 13-15 mm).
S. belang and S. laotica share the notched inner peristome but S. belang has a relatively flat spire and an outer peristome with a wing-like extension, unlike the taller-spired S. laotica with a simple outer peristome. The variation in shell dimensions of S. belang overlaps with that of S. laotica (shell height 5.5 mm, shell width 9.5 mm).
S. belang and S. vanbuensis share the notched inner peristome but S. belang has an outer peristome with a wing-like extension while S. vanbuensis has a simple, non-extended outer peristome. The shell of S. belang is slightly larger than that of S. vanbuensis (shell height 5 mm, shell width 8.5-10 mm).
The periostracal hairs of S. belang are present at the sutural channel only, whereas parallel rows of periostracal hairs are located above and below the periphery in S. locardi. S. belang has a notched inner peristome and a wing-like outer peristome at the parieto-palatal area whereas S. locardi has a simple circular peristome. The variation in shell sizes and dimensions of S. belang overlaps with that of S. locardi (shell height 5 mm, shell width 11-14 mm).
S. belang has a notch at the inner peristome in the parieto-palatal area and tightly coiled whorls while S. franzhuberi has a simple peristome and more rapidly expanding whorls. S. belang has a lower shell and smaller aperture compared to S. franzhuberi (shell height 6.0-6.4 mm, shell width 12.6-12.7 mm, aperture height 4.9-5.3 mm, aperture width 5.3-5.7 mm, shell height to shell width ratio 0.48-0.51).
S. belang has periostracal hairs at the suture, a notched inner peristome and a wing-like extension at the outer peristome while S. tonkiniana differs in having periostracal hairs throughout many parts of the shell and a simple, circular inner and outer peristome. The variation in dimensions of S. belang partly overlaps with that of S. tonkiniana (shell height 4 mm, shell width 10-13 mm). Remarks. There is an intraspecific variation in the degree of expansion of the wing-like structure in the outer peristome at the parieto-palatal region but the notch of the inner peristome remains a constant character in every studied population of S. belang . The periostracum and periostracal hairs at the suture are present in live individuals across all populations of S. belang.
Scabrina resembles Japonia Gould, 1859 and Lagocheilus Blanford, 1864 in its hairy periostracum, proteinaceous operculum and circular aperture with a notch at the parieto-palatal area, but differs from the other two genera in its more discoid shell, operculum with slightly raised edges and much wider umbilicus (blanFord 1864, KobElt 1902, lEE et al. 2008, vErMEulEn et al. 2015, hirano et al. 2019. The record of Scabrina belang in Peninsular Malaysia represents the first record of Scabrina in this region, as this genus was not known to occur there prior to this study (hEMMEn & hEMMEn 2001, BEDO 2017, MaassEn 2001, Foon et al. 2017, PhunG et al. 2018. We note that S. thaitieni Thach, 2021 from southern Vietnam has a calcareous operculum with spiral lamellae exterior and a proteinaceous interior, which indicates an affinity to the genus Cyclotus Guilding in Swainson, 1840 rather than Scabrina (swainson 1840, blanFord 1864, KobElt 1902, EGorov 2009). Etymology. The species name refers to the Malay word for striped "belang", used as a noun in apposition, for the distinctive brown markings on its shell. In addition, the name is also a homage to the Malayan tiger, known as "harimau belang" in Malay.