T. lowei and T. triangularis appear to form a new section of Typhis, defined thus: Shell with three broad varices continuous from whorl to whorl, ascending the spire in a slowly revolving spiral. Tubes wholly concrescent with the posterior angles of the varices, where they are terminal. Type T. lowei.
It differs from Pterotyphis (=Trigonotyphis) of Jousseaume by the complete concrescence of the tubes with the varices; in Pterotyphis the tubes shortly precede the varices. In Poropteron Jouss. the tubes are not wholly closed in front, but its resemblance to the present group is striking, and possibly there is some direct relationship.

The shells are small to moderately large. Each whorl bears three broadly winglike varices, each varix coalescent with an anal siphonal tube. The shell is white, white with brown bands, or entirely light brown. Most species are covered with a thick, white, minutely frilled intritacalx. The typically muricinc radula also serves to distinguish this group from most other typhine groups, these having aberrant muricine features.

The genus Tripterotyphis was once regarded as a subgenus of Pterotyphis (Vokes, 1996: 5) although that genus has a distinctly different morphology including an abapically flaring final lip, especially anteriorly, much more numerous and finer spiral cords, with a far less projecting functional tube, distinctly placed far behind the final varix, suggesting a distinct lineage, divergent from Tripterotyphis.
Ten species are currently assigned to the genus Tripterotyphis, including two new species described herein, which comprise five taxa from the eastern Pacific: T. arcana (DuShane, 1969), T. fayae (Keen & Campbell, 1964), T. lowei (Pilsbry, 1931), T. galapagosensis n. sp. and T. jamesmacleani n. sp.; one from the western Atlantic: T. triangularis and four from the western and southern Pacific: T. colemani (Ponder, 1972), T. norfolkensis (Fleming, 1962), T. robustus (Verco, 1895) and T tenuis Garrigues, 2020.
Description: Shell up to 26.6 mm in length. Protoconch paucispiral of 1.5-2 whorls. Teleoconch whorls with three varices per whorl from first to last whorl. Shoulder spine tubelike, ventrally sealed along its entire length. Aperture small, ovate. Shell covered by thin, whitish intritacalx. Siphonal canal short, ventrally sealed. Operculum strongly ovate with apical nucleus.