Shell fusiform, whorls convex, suture impressed, channelled in some species, aperture length about equal to spire, siphonal canal short, protoconch domeshaped and glassy. Axial sculpture predominant, spiral sculpture weak to absent, parietal notch often present, inner lip often lirate, columella with 4 pleats progressively decreasing in strength towards base. Size small for family, ranging 4 to 15mm in length.
The genus Austromitra comprises of approximately 30 species which inhabit the waters of South Africa, St. Helena, the lower half of Australia, Tasmania & New Zealand. In fact, the genus Austromitra (L) means Mitra from the south referring to the southern hemisphere. South African fauna consists of nine species with a further three species described here. All species listed from South Africa are endemic to this region. Shells are small to minute, the molluscs are active predators, feeding on soft tissues and body fluids of sand shrimps, ascidians and sometimes carrion. They inhabit rock crevices and burrow shallowly in sand. The egg capsules are blister-shaped, attached by a flat base to the substrate. Most species live in the infratidal region and are seldom washed up, the only exception being A. capensis. Animal reported to be pale cream in colour. Radula very short, rachidian tooth broad and short, bearing up to 15 pointed cusps and lateral tooth hook-shaped.

Distribution and habitat New Zealand, Central Indo-Pacific and South Pacific, from intertidal to upper bathyal depths. Remarks The results of our phylogenetic analyses suggest that Austromitra in its currently accepted extension comprises several unrelated or distantly related lineages. Althougha low dome-shaped protoconch is considered one of the key diagnostic features of Austromitra, A. rosa sp. nov., the species most closely related to the type species, A. rubiginosa, has a markedly different protoconch morphology. Furthermore, Ponderiola n. gen., the sister group of Austromitra (as defined herein), is distinctive due to a characteristic "bullet-shaped" protoconch which resembles neither the protoconch of .4 rubiginosa, nor of A. rosa sp. nov. Three further temperate South hemisphere lineages: Cernohorskyola n. gen., Kilburniola n. gen., and Vexillum laenum clade, also possess a low dome-shaped protoconch similar to that in A. rubiginosa but are, a part of, or more closely related to Vecilium. These observations suggest that the taxonomic value of protoconch morphology has been overestimated in the past, as the shift to paucispiral protoconch (and as well, lecitotrophic development) has obviously occurred multiple times in the evolutionary history of Costellariidae (see also Bouchet 1990). Therefore, we here disregard protoconch morphology as a generic attribute of Austromitra. The genera inferred from phylogeny that earlier would have been placed in Austromitra cannot be readily differentiated based on morphological (shell) grounds. For example, typically, the presence of both, axial and spiral sculpture on spire and last whorl differentiate Austromitra from Ponderiola n. gen. and Cernohorskyola n. gen. However, the degree of pronunciation of the spiral sculpture may vary considerably, and some variable species from unrelated lineages, such as A. rubiginosa, or C. analogica, can display closely comparable sculpture patterns. Therefore, further studies are necessary to allocate with certainty species hitherto placed in Austromitra. It is also possible that future molecular studies of Southern temperate water faunae, such as the one from New Zealand (Marshall & Marrow, 2021) will reveal additional new lineages of Costellariidae. To avoid premature unsupported allocations, we here re-classify only those species for which we have data supporting their affinity to one of the newly described lineages, and conversely we maintain in Austromitra those for which molecular data are currently unavailable.

Key to the South African species of Austromitra
(1)
* Suture canaliculate (2)
* Suture not canaliculate (3)
(2)
* Colour uniform pink; shape ovate-fusiform, aperture subequal to spire; paries without a small nodule posteriorly; axial ribs close-set and thin, numbering 16-18 on penulti¬mate whorl, spiral lirae conspicuous throughout; range. Port Alfred to Kwelera ....bathyraphe (Sowerby, 1900)
* Colour variegated brown with a median pale zone; shape narrow fusiform, spire markedly longer than aperture; paries with a distinct small nodule in the posterior angle of the aperture; axial ribs wide-set and broad, but rather low, 10-12 on penultimate whorl; spiral lirae visible only on base; range. Port Alfred to Xora. ......canaliculatum (Sowerby, 1900)
(3)
* Columella pleats subequal in strength; colour pure white, later whorls with a conspicuous median chestnut-brown band; protoconch diameter 0,88-0,9 mm; range, Port Alfred to Kwelera .........euzonatum (Sowerby, 1900)
* Columella pleats strong posteriorly, becoming progressively weaker basally; colouration never as above; protoconch diameter 0,7 mm or less ..........(4)
(4)
* Suture deep, bordered below by a rounded shoulder; spiral lirae well developed; axial ribs extend on to base, rendering the rostral lirae nodulous; colour uniform white or pink; range, Port Alfred, also [fide Barnard, 1959) off Umkomaas and Tugela mouth ......kowieensis (Sowerby, 1901)
* Suture shallow or moderately deep, whorls not shouldered, spiral lirae feeble (except
on base); axial ribs not extending on to base, rostral lirae not nodulous; colour not uniform white or pale pink ...........(5)
(5)
* Colour variegated brown with a whitish or fawn median zone; posterior angle of aperture rarely with a distinct parietal nodule; sutures shallower, rostral lirae somewhat weak, axial ribs often obsolete on last whorl; range. False Bay to Tongaat .........capense (Reeve, 1845)
* Colour deep orange-red to pink with a white median zone, or else banded with pink, brown and white; posterior angle of aperture always with a distinct parietal nodule in adults; sutures deeper, rostral lirae rather strong, axial ribs never obsolete on last whorl (except sometimes just behind the lip); range, Kwelera to Port Shepstone ..........rhodarion.