Pterocyclos tenuilabiatus (Metcalfe, 1851)
“Belonging to the genus Pterocyclos of Benson.” (Metcalfe, 1851)
“An elegant, narrowly discoid species, in which the sinus, continuous with the outer expanded lip, is thinly broadly dilated, wing-like.” (Reeve, 1864)
“Weichtheile schwärzlich, Fühler zugespitzt, die Augen klein, schwer zu sehen, an ihrer Basis nach aussen und hinten. Die Exemplare von Metcalfe sind kleiner, unbehaart und kommen vermuthlich von Sarawak. Das Leydener Museum erhielt Exemplare von Resident Schwaner in Borneo.” (Martens, 1867)
“Il mollusco dei Pterocyclos è quasi identico a quello degli Opisthoporus che sarà descritto più innanzi. Nella specie sopraindicata la testa è piccola, piatta, nera; il muso è munito di un ampio velo bilobato, sotto al quale si nasconde la bocca. I tentacoli sono conici, piuttosto brevi e larghi e portano gli occhi al lato esterno della base.” (Issel, 1874)
“The specimens from Mount Kenepai are very large, the largest having a diam, maj. of 34 mill. The only one collected by Dr. Hallier is a young specimen.” (Schepman, 1896)
Metcalfe (1851) original descriptions on Cyclostoma tenuilabiatum – “C. testâ discoideâ, spirâ depressâ, planâ, colore pallida, supernè, castaneo-maculata et undulatâ; epidermide luteo-castaneâ, indutâ; anfractibus 5 rotundatis, 4 primis laevibus, ultimo lineis impressis irregularibus ruguloso; suturâ impressâ; aperturâ circulari; peritremate duplici; interno simplici, supernè emarginato; externo tenui, lato, planiusculo, supra ascendente, fornicato, dein compresso; umbilico patulo; anfractibus intus distinctis.”
Gray (1852) descriptions on Pterocyclos tenuilabiatus – “Shell depressed, subdiscoidal, solid, striate, and with transverse impressions on all sides, brownish, marmorated with darker chestnut-coloured angulose stripes; spire fiat, rather concave, with the apex a little prominent; whorls 4½, moderately convex, rapidly increasing, the last one rather depressed; umbilicus broad; aperture diagonal, nearly circular; peristome double; internal edge shortly produced, a little indented above; external edge nearly continued, white, with the columellar margin shortly reflected; right margin dilated, expanded; upper margin raised like a cap near the penult whorl.”
Martens (1867) descriptions on Pterocyclos tenuilabiatus – “Testa discoidea, latissime umbilicata, perpendiculariter striatula, pubescens, fulvolutea, superne maculis fulguratis rufocastaneis picta; apex rufocastaneus, vix prominens; anfr. 4½, sutura profunda discreti, supra planiusculi, infra convexi, ultimus antice parum descendens; apertura diagonalis, circularis; peristoma duplex, internum lacteum, externum late reflexum, tenue, in vivo fuscum, superne in lobum fornicatum anfractui ultimo adnatum excurrens. Operculmn calcareum, brunneum, intus paululum concavum, spiris circa 6 margine lamelloso, elevato, sulco marginali lato.”
Kobelt (1902) descriptions on Pterocyclus tenuilabiatus – “Schale sehr weit genabelt, scheibenförmig, gestreift, bräunlich gelb, oben mit kastanienbraunen Zickzackstriemen; Apex kaum vorspringend, rotbraun; Naht tief; 4½ oben ziemlich flache, unten gewölbte Windungen, letzte vorn wenig herabsteigend; Mündung diagonal, kreisrund; Mundrand doppelt: innerer milchweiss, äusserer breit zurückgeschlagen, dünn, braun, oben in einen dachförmigen, angedrückten Lappen ausgezogen.”
Reeve (1864) descriptions on Pterocyclos tenuilabiatus – “Shell very largely openly umbilicated, narrowly discoid, wave-marbled throughout with fulvous chestnut, whorls rounded, somewhat obscurely diagonally malleated, closely ring-striated; aperture rather small, oblique, lip flatly reflected, sinus thinly broadly dilated.”
Cyclostoma tenuilabiatum - “Long. 1 1/10; lat. 6/10; alt/ 3/10 unc.” (Metcalfe, 1851); Pterocyclos tenuilabiatus – “Operc. ? Height 6½, greatest breadth 26, least br. 21 mill.” (Gray, 1852); Pterocyclos tenuilabiatus – “Diam. maj. 30, min 22, alt. 13: apert. lat. = long. 12 Mill.” (Martens, 1867); Pterocyclus tenuilabiatus – “H. 13, Durchm. 30:22 mm.” (Kobelt, 1902)
Type locality – “Borneo” leg. W. J. Hamilton/Nov. 1850 (Metcalfe, 1851)
Other localities – “W Borneo, Bengkajang am Fuss des Berges Pandon. der das Flussgebiet der Ströme Kapuas und Sambas trennt, mehrere leidende Exemplare im feuchten Laub am Fuss eines Felsblockes.” (Martens, 1867); “Territorio di Sarawak” leg. Doria and Beccari (Issel, 1874); “Kusan and Penggiron districts in South-eastern Borneo” leg. W. Doherty (Aldrich, 1889); “Southern foot of Mount Kenepai and Smitau” leg. Büttikofer, “Mount Dadap and Sekedau” leg. Moret, and “Mount Liang Gagang” leg. Hallier (Schepman, 1896); “Minahassa” (Kobelt, 1897).