Horaiclavidae
This family shares many characters with Pseudomelatomidae, conchologically differing by a small stout shell with short siphonal canal and usually poorly developed spiral sculpture. Genera currently included in Horaiclavidae have been usually included in the Crassispiridae (= Pseudomelatomidae), and the clear molecular-based division between the two clades seems to be not so clearly reflected in shell-based distinction. Therefore, the generic composition of the family is somewhat provisional and needs confirmation by further molecular data and/or a detailed analysis of conchological and radular characters.
From Bouchet et al. 2011: Shell generally small, 5 – 25 mm, usually 7 – 15 mm high, shortly claviform, with relatively low spire and a short, truncated, poorly differentiated siphonal canal. Subsutural ramp usually poorly differentiated. Axial sculpture almost always present, usually as strong sinuate ribs. Spiral sculpture normally weak or obsolete, often with glossy shell surface. Anal sinus on subsutural slope, weak to moderately deep, often constrained by callus. Protoconch of up to 3.5 medially carinate but otherwise smooth whorls when multispiral, but usually paucispiral and smooth.
In living taxa:
Operculum with terminal nucleus. Radular formula: 1-0-0-0-1. Marginal teeth duplex, with lanceolate major limb and usually narrow accessory limb, which is inserted in a shallow socket. Major limb often with angulation lateral to the place of accessory limb insertion.