Shell of medium size for the genus, height: 9-14 mm (mean: 11.03), width: 4-5.2 mm (mean: 4.5) [4.3]. Sub-fusiform solid, cylindrical, slender. H/W 2.22-2.64, mean: 2.45.
Protoconch multispiral. According to Manousis et al. (2017: 28-29) the protoconch is 400 µm (mean) wide and 440 µm (mean) high, bears a protoconch I of 221 µm (mean) and consists of 3.0 convex whorls with nucleus decorated with diagonally cancellate striae and the last whorl with a weak keel before the onset of the teleoconch." Teleoconch of 6-7 convex whorls, with marked suture. Scattered microgranules on the surface on the first whorl of the teleoconch including the ramp. Axial sculpture of 15-21 orthocline robust ribs, and interspaces slightly wider than the ribs. Spiral sculpture of 6-7 cordlets above the aperture, narrower than the axial ribs. Cancellation rectangular, with small and elongated tubercles at the intersections. Tubercles narrow and spinulose in subadult specimens. Sculpture visible in transparency throughout the internal shell wall. Subsutural ramp narrow. Columella simple, slightly sinuous medially, gently angled posteriorly.
Outer lip with 10-11 strong inner denticles, the most anterior larger and blunt, delimiting the siphonal canal, the most posterior delimiting the anal sinus. Anterior sinus short and wide. Siphonal f asciole with 8-9 strong nodulose cords. Coloration uniformly tawny-reddish, sometimes very dark, with whitish blotches as wide as two axials usually vanishing towards the suture. Soft parts foot sharply bilobed anteriorly, with a small papilla near each tip. Black eyes at proximal 1/3 of the tentacles. Foot and cephalic tentacle whitish hyaline semitransparent, with brigth white speakles, head semi-transparent dark grey, siphon dark grey with a yellow¬ish stripe covered with white speakles (based on Manousis et al., 2017: 30 fig. 4).

R. locardi differs from R. bicolor by its more elongated and slender outline, its white blotches shading adapically (never shading in R. bicolor). It differs from R. atropurpurea by its more numerous axial ribs, and the lack of a white cordlet above the aperture. R. laviae with white blotches is similar, differs being more pupoid, smaller and with different knobs.

Ajaccio (Corsica)(type-location). Other finding places: Sicily - Termini Imerese (Palermo), 1 sh (PUS); S. Elia -Porticello (Palermo), 3 sh (GIR); Palermo, 2 sh (PUS); Isola delle Femmine (Palermo), 1 sh (SER); Golfo di Ca-rini 1 sh (PUS). Italy - Isola d'Elba, 1 sh (BAR); Napoli, 1 sh (PUS); Scilla (Reggio Calabria), 1 sh (VAZ); Brindisi 22 m, 1 sh (SMR); Torre Ovo (Taranto), 1 sh (REN). Greece - Saronikos Gulf, 2 sh fide Manousis et al., 2017. Cyprus - Ayia Napa, 1 sh (GIR). Turkey - Bozcaada Is., 2 sh (PUS).