Diplommatina gomantongensis (E. A. Smith, 1894)
“D. Aldrichi of Godwin-Austen is allied to this species, but is more tapering above and has a different peristome and a stronger columellar tooth. The lamellae are about eighteen in number on the penultimate volution.” (E. A. Smith, 1894)
“This is one of several species that are known only from Gomantong Hill. The two adults were 3.3 and 3.4 mm high. The elongated shell form with conical spire and larger size easily separates D. gomantonensis from Arinia inexpectans that is found at the same spot.” (Solem, 1964)
E. A. Smith (1894) original descriptions on Diplommatina symmetrica – “Testa dextrorsa, imperforata, fusiformi-ovata, pallide lutea, versus apicem rufescens; anfractus 7.5, perconvexi, regulariter crescentes, sutura profunda sejuncti, costulis tenuissimis lamelliformibus breviter obliquis numerosis instructi, inter costas laeves, ultimus penultimo subangustior, contractus; apertura parva, subcircularis, cum peristoma longit. totius 0.29 adaequans; peristoma duplex, luteum, margine externo valde incrassato, ad columellam angulatim producto, supra parietem tenui.”
Kobelt (1902) descriptions on Diplommatina (Diplommatina) gomantonensis – “Schale rechtsgewunden, ungenabelt, ei-spindelförmig, mit zahlreichen, feinen, schrägen, lamellenartigeu Rippen, dazwischen glatt, blass gelblich, oben rötlich; Naht tief; 7½ sehr gewölbte, regelmässig zunehmende Windungen, letzte schmaler als die vorletzte, eingezogen; Mündung klein, fast kreisrund, mit dem Mundrande 2/7, der Höhe einnehmend; Mundrand doppelt, gelb, äusserer sehr verdickt, an der Spindel eckig vorgezogen, an der vorletzten Windung schmal.”
Vermeulen (1993) descriptions on Diplommatina gomantonensis – “Shell dextral, fusiform, penultimate whorl widest; sides flat. Whorls 6 ¼-7 5/8, convex. Suture impressed. Constriction level with the parietal side of the peristome, well away from the palatal side, with 1 transversal palatalis; a very inconspicuous columellaris is present half-way the tuba. Tuba ¾-7/8 whorl. Radial ribs straight, distinct, high, rather thin, rather widely spaced to rather densely placed (3-5 ribs/0.5 mm on the penultimate whorl). Spiral striation usually present. Umbilicus closed. Aperture hardly tilted with regard to the coiling axis; columellaris not visible. Peristome double, expanding; palatal side moderately sinuous, with a moderate edge; basal side with or without a slight ege; basal edge not or slightly sinuous, sharp or somewhat protruding; outer peristome expanding beyond the inner or not; inner peristome with a palatal lip, usually free and slightly erect on the columellar side, somewhat expanding on the parietal side.”
Diplommatina symmetrica – “Longit. 3.5 millim., diam 1.5. Apertura cum peristoma 1 longa.” (E. A. Smith, 1894); Diplommatina gomantonensis – “Height 2.5-3.5 mm; width 1.2-1.6 mm; inex 1.9-2.4. Height and width aperture 0.5-0.6 mm.” (Vermeulen, 1993)
Type locality – “Gomanton Hill, N. Borneo” (E. A. Smith, 1894)
Other localities – “Borneo. Sabah. Interior Zone: Batu Punggol SE. Of Sepulot” (Vermeulen, 1993); “Borneo. Sabah. Sandakan Zone: Batu Putih near road Lahad Datu-Sandakan, near Kinabatangan R.” (Vermeulen, 1993); “Borneo. Sabah. Sandakan Zone: Batu Laab near road Lahad Datu-Sandakan, near Kinabatangan R.” leg. Wilford (Vermeulen, 1993); “Borneo. Sabah. Sandakan Zone: Bukit Gomantong, 30 km S. of Sandakan” (Vermeulen, 1993); “Borneo. Sabah. Sandakan Zone: Batu Tumanggong Besar, 1 mile downstream Sukau, along Kinabatangan R.” leg. Wilford (Vermeulen, 1993); “Borneo. Sabah. Sandakan Zone: limestone escarpment along S. Tabin, lower Segama Valley” leg. Wilford (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: NW. of road Lahad Datu-Sandakan crossing with Segama R.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: ‘Kirk’s Cave’, 8 km N. of Lahad Datu.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: G. Madai, 40 km SSW of Lahad Datu.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: G. Baturong, 50 km WSW of Lahad Datu.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: Bt. Pababola, Segarong Hills 25 km ESE of Kunak.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: Batu Tenggar, Sengarong Hill 25 km ESE of Kunak.” (Vermeulen, 1993); “Borneo. Sabah. Tawau Zone: small limestone outcrop 15 miles NNW of Kalabakan.” Leg. Wilford (Vermeulen, 1993)