A new land snail, Arinia (Notharinia) micro (Caenogastropoda: Cyclophoroidea: Diplommatinidae), from a limestone karst in Perak, Peninsular Malaysia Marzuki, Mohammad Effendi bin Foon, Junn Kitt Raffles Bulletin of Zoology 2016 2016-10-19 64 313 318 GMR4 Marzuki & Foon Marzuki & Foon 2016 [813,1305,1669,1694] Gastropoda Diplommatinidae Arinia Animalia Architaenioglossa 1 314 Mollusca species micro sp. nov. Notharinia   Figs. 1, 2   Type material.  Holotype(BOR/MOL 6227) and paratypes(BOR/MOL 6228/2; ME0000883/>10): Malaysia, Perak, central Gunung[=Mountain] Rapat, limestone outcrops in Kek Lok Tong, approximately 6.9 kilometres south of Ipoh, 4°33’13.45”N, 101°7’50.34”E, coll. M.E. Marzuki,  26 May 2011.   Diagnosis.Shell minute, cylindrical, translucent. Whorls 4.5. All whorls except the protoconch sculptured with dense, prominent, thin radial ribs. Spiral ridges very fine, evenly spaced and distinct. Last part of body whorl detached, peristome not touching the ultimate whorl. Umbilicus deep. Peristome simple, reflected at the parietal area but not the palatal and basal areas.   Description.Shell minute, delicate, dextral. Color dull white, translucent. Suture deeply impressed. Whorls 4.5, convex. Apical whorl depressed conical, width of the antepenultimate, penultimate and ultimate whorl consistent, thus shell appears cylindrical. Periphery rounded for all whorls. Apex somewhat sunken, slightly depressed and concave. Protoconch rounded, smooth, distinctly oblique at 25 degrees to the teleoconch. Teleoconch commences with abruptly sculptured orthoclinic radial ribs. Radial sculpture is present on all whorls except the protoconch and is characterised by dense, straight, pronounced, sharp thin ribs. Radial ribs slightly sinuous particularly on apical and ultimate whorls. Radial rib density varies ontogenically, ribs more loosely spaced at the start of the teleoconch, denser at the apical and antepenultimate whorls (10 ribs per 0.1 mm), less dense at the penultimate and ultimate whorls (6 ribs per 0.1 mm) and very dense towards the terminal of the ultimate whorl (7 ribs in 0.04 mmbefore the aperture, equivalent to 17.5 ribs per 0.1 mm). Internal constriction present, but not conspicuous. Spiral ridges between radial ribs very fine, evenly-spaced, distinct and are present on all whorls except the protoconch. Shell rimately perforate, last whorl loosely-coiled, slightly detached, revealing a deep umbilicus. Aperture simple, circular, white. Peristome simple, well-rounded, thickened and reflected at the parietal area but not the palatal or basal area, not touching the ultimate whorl. Operculum not examined.  Dimensions ( Table 1).Shell height 0.80–0.90 mm, mean 0.85 mm; Shell width 0.34–0.35 mm, mean 0.35 mm; Aperture height 0.24–0.42 mm, mean 0.31 mm(n=3).   Etymology.From the Greek  micro, meaning small, in reference to the remarkably smaller shell of matured individuals of the species compared to its four known congeners.  Habitat and ecology.  Arinia( Notharinia) microinhabits thickly vegetated lowland rainforest on and near limestone karsts. Living individuals were observed crawling among leaf litter and plant debris in sheltered and damp microhabitats near limestone rock outcrops.  Table 1. Shell measurements (mm) for  Arinia( Notharinia)species. Measurements of  Arinia( Notharinia) attenuata,  Arinia( Notharinia) brevior,  Arinia( Notharinia) crassilabris, and  Arinia( Notharinia) linneiwere sourced from Vermeulen et al. (2007) and Maassen (2008).     Specimen  Shell Height  Shell Width  Aperture Height    Arinia( Notharinia) attenuata Vermeulen, Phung & Truong, 2007 1.70–1.90 0.75–0.85 0.45–0.50    Arinia( Notharinia) brevior Vermeulen, Phung & Truong, 2007 1.50–1.60 0.85–0.90 0.50–0.55    Arinia( Notharinia) crassilabris Vermeulen, Phung & Truong, 2007 1.60–2.05 0.65–0.75 0.50–0.60    Arinia( Notharinia) linnei Maassen, 2008 1.58–2.16 0.84–0.99 NA    Arinia( Notharinia) microMarzuki & Foon, new speciesHolotype (BOR/MOL 6227) Paratype 1 (BOR/MOL 6228/1) Paratype 2 (BOR/MOL 6227/2) Mean (Holotype, Paratype 1 and Paratype 2) 0.90 0.85 0.80 0.85 0.35 0.35 0.34 0.35 0.25 0.26 0.24 0.25  Conservation status.This species is vulnerable to habitat loss as the Gunung Rapat karst complex is completely isolated from other natural rainforest and karst habitats because of intensive human developments, such as ex-tin mining ponds, agriculture, roads and residential areas. Although the typelocality is within cave temple grounds, which provides the local population of  Arinia( Notharinia) micronominal protection from other land uses, the southern and central parts of the same karst complex are being rapidly subjected to destructive limestone quarrying activities.   Remarks.  Arinia( Notharinia) micronotably differs from its congeners by its distinctly smaller shell. Like other  Arinia( Notharinia)species, specimens of  Arinia( Notharinia) micromay vary slightly in shell size (see Table 1), which has been suggested to be due to sexual dimorphism by Maassen (2008). Matured shells of  Arinia( Notharinia) microconsistently comprise of 4.5 whorls compared to 4.5–5.0 whorls in  Arinia( Notharinia) linnei, 5.0–5.4 whorls in  Arinia( Notharinia) attenuata, 4.1–4.5 whorls in  Arinia( Notharinia) breviorand 5.5 whorls in  Arinia( Notharinia) crassilabris. The radial ribs in  Arinia( Notharinia) microare more pronounced and well-developed compared to  Arinia( Notharinia) linnei. The ultimate whorl of  Arinia( Notharinia) microis more loosely coiled and detached than  Arinia( Notharinia) breviorand is distinct from the tightly coiled  Arinia( Notharinia) attenuata,  Arinia( Notharinia) crassilabrisand  Arinia( Notharinia) linnei. The deep umbilicus is visible in  Arinia( Notharinia) micro, a feature not found in other congeners except  Arinia( Notharinia) linnei. The umbilicus of  Arinia( Notharinia) linneiis only partially visible due to obstruction by the ultimate whorl. The peristome of  Arinia( Notharinia) microis simple, a feature shared by only one other species,  Arinia( Notharinia) attenuata. Interestingly, fine spiral ridges between the radial ribs are present in both Peninsular Malaysian species,  Arinia( Notharinia) microand  Arinia( Notharinia) linnei, but is absent in the Vietnamese species (see Vermeulen et al., 2007). 2011-05-26 M. E. Marzuki Malaysia central Gunung 4.553736 Kek Lok Tong 1 101.13065 Rapat 1 314 2 Perak holotype