Dyakia regalis (Benson, 1850)
“The subnodulous costate appearance of the whorls, above the ultimate one, forms a very peculiar feature in this handsome sinistrorse species. The following corrected and more extended characters of a fine and remarkable East Indian Helix, published by me in the Journal of the Asiatic Society of Calcutta for 1836, and copied thence into Pfeiffer's ‘Monograph’ will not be out of place here.” (Benson, 1850)
“Gli individui di questa specie da me osservati si possono ascrivere, per le proporzioni loro , alla forma distinta da V. Martens colla lettera B, e, rispetto al colore, si riferiscono alla sua mutazione n.° 5 (var. α di Adams).” (Issel, 1874)
Benson (1850) original descriptions on Helix regalis – “T. perforata, sinistrorsa, conoideo-depressa, carinata, eleganter fasciata vel unicolori; anfractibus 6, angustis, subplanatis, supra striis acute corrugatis, obliquis, strias spirales decussantibus, medianis obsolete noduloso-costatis, ultimo carinato, carina infra compressa, subtus nitido, convexo, radiato-striato, striis circularibus versus umbilicum obsoletis; periomphalo excavato; apertura obliqua, subsecuriformi, peristomate acuto, margine inferiori arcuato, versus umbilicum sinuato, columellari brevissime reflexo. α. costis inconspicuis; anfractibus supra fascia media luteo-fusca, utrinque linea fusco-nigra marginata, fasciisque albido-csesiis marginalibus ornatis, ultimo subtus fascia media, cinereo-lutea, lata, utrinque fascia angusta purpureo-fusca cincta, margine albido, periomphalo albido-luteo. β. unicolori, extus intusque purpureo-fusca, costis magis conspicuis.”
Martens (1867) descriptions on Nanina regalis – “Testa sinistra, perforata, conico-depressa, acutissime carinata, conferte spiratim striata, superne striis argutis confertis inaequalibus (minutim granulosis) hie et illie grossioribus, rugaeformibus sculpta, opaca, infra leviter striatula, nitida, colore varians; spira breviter conica; anfr. 6, lente crescentes, planiusculi, sutura superficiali conjuncti, ultimus basi parum convexus, antice haud descendens: apertura diagonalis, securiformis; peristoma rectum, acutum, margine basali valde arcuato, columellari ad insertionem brevissime reflexo.”
Tryon (1886) descriptions on Nanina regalis – “Perforate, closely undulately striate and granulate, fasciated or unicolored; whorls 6, the last not descending, shining below, very minutely decussated, the circular striae obsolete towards the umbilicus.”
Tryon (1886) original descriptions on Nanina regalis unicolor – “Purple-brown.”
Tryon (1886) descriptions on Nanina regalis vittata – “Undulating striae less conspicuous, lighter colored, with four reddish bands, carina and umbilical area yellowish.”
Tryon (1886) original descriptions on Nanina regalis major – “More depressed, reddish brown, without bands, umbilical area white.”
Helix regalis – “Diam. maj. 27, minor 25, axis 13 mill.” (Benson, 1850); Nanina regalis – “Diam. maj. 29-30, min. 25-27, alt. 15½-28½; apert. long. 13-16, alt. 9½-12 Mill.” (Martens, 1867); Nanina regalis – “Diam., 27 mill. Borneo.” (Tryon, 1886); Nanina regalis major – “Diam. 34 mill.” (Tryon, 1886)
Type locality – “ad Sarawak, Insulee Borneo” leg. W. Taylor (Benson, 1850)
Other localities – “Nordöstl. Borneo, bei Balambangan” (Martens, 1867); “Territorio di Sarawak” leg. Doria and Beccari (Issel, 1874); “Northern Borneo” leg. J. Whitehead (E. A. Smith, 1887)
“A couple of specimens of each variety, found on the ground, in jungle, near Sir Jas. Brooke's house at Sarawak, were brought to England by Lieut. W. Taylor, Madras Artillery, to whom I am indebted for an example of each kind.” (Benson, 1850)