Two New Species of Micro Land Snails from Two Islands in the Andaman Sea (Prosobranchia: Diplommatinidae; Pulmonata: Pupillidae)

Abstract

Two new species of pupillid and diplommatinid micro land snails from two islands in the Andaman sea are described. They are Diplommatina insularis n.sp. from Similan island and Gyliotrachela phoca n.sp. from Lanta Yai island. Diplommatina insularis n.sp., has fusiform, dextral, with about 5 ¾ angular whorls. Penultimate whorl is slightly larger in diameter than the body whorl. Shell sculpture has moderately spaced radial ribs and fine with moderately spaced spiral striation from the teleconch through the last whorl. Umbilicus is closed. Peristome is expanded and duplex. Aperture is round, with well-developed nodule columellar. Gyliotrachela phoca n.sp., has conical spire, a moderately long, upwardly directed tuba. The protochonch appears pitted and has spirally striated at the boundary with the teleconch. The shell is moderately umbilicate, its last whorl weakly redial riblets. There are five major apertural barriers (parietal, angular, columellar, upper and lower palatals), and additional numerous small lamellae and plicae: two infraparietal lamellae, two supracolumellar and two subcolumellar lamellae, two infrapalatal plicae, two interpalatals and four suprapalatal plicae. All of the apertural barriers have spinose surfaces.