Type material: Holotype (29.4mm wide x 12.2mm high) deposited at Paris National Museum of Natural History, France with Registration No MNHN-IM-2000-38151. Other material: Paratype 1 (29.3mm) in Dr Thach collection. Paratype from type locality. Type locality: Vieng Xai area, Houaphanh Province, Laos. Habitat: among leaf litter
Diagnosis: The new species is characterized by special shape of air tube, very rugose surface and rather flat protoconch whorl.
Description: Shell medium-sized for the genus and depressed-heliciform with low spire and very deep sutures. Shell height 44% of width . Apical whorl flat and whitish, body whorl concave along suture and ornamented with dark brown band along periphery. Air tube ascending and tilted 85° at frontal view and touching the remaining shell.
Sculpture cancellate with many pits formed by intersections of spiral and radial ribs. Ventral side strongly convex and sculptured with bifurcate and closely-spaced radial ribs. Aperture rounded and occupying 81.5% of shell height, 36.0% of shell width, outer lip double, thick and slightly reflected. Umbilicus widely open. Color pinkish with white radial stripes at dorsal side and white at ventral side.

Comparison: The new species is close to Rhiostoma laosense Tongkerd & Inkhavilay (2023) but differs mainly as follows: (1) air tube having different shapes and steeply ascending, not descending, (2) spire flatter, (3) apex sunken, not visible at frontal view, (4) outer surface rougher with different sculpture, (5) sutural area more concave, (6) body whorl lower, less inflated with lower side more descending, (7) different localities in Laos, Houaphanh Province, versus Borikhamxay Province, about 500 kilometers apart.
Etymology: The new species is named for the Houaphanh Province of Laos where the type material was collected.