Prunum curtum

Prunum curtum is a small marine snail of the family Marginellidae, order Neogastropoda ^[1]. It was described in 1832 from material collected at Iquique, in Chile, and at Paita, in Peru ^[2]. It is one of the few species of its family known with certainty off the west coast of South America, a region whose marginellid fauna is regarded as very poor in known species, probably for lack of sampling ^[3].

The shell is grayish yellow or grayish brown, with lighter flecking whose amount varies from one specimen to another ^[2]. The body whorl is short and broad, with a swollen angulation on its upper part, and seen from the ventral side the anterior end looks cut off square ^[2]. The specimen from Laguna Grande, in Ica, illustrated in that work is 17.8 mm long ^[2].

The outside of the outer-lip callus is a brownish orange, and the same tint often spreads, sometimes widely, along the edge of the parietal callus; the inside of the aperture is frequently brown ^[2]. These features help to separate it from Prunum macleani, whose type specimen is 36.6 mm long, is rose-coloured and has a more elongate body whorl, although small specimens of that species found off La Plata Island (Ecuador) resemble it superficially ^[2].

No verified type material of Prunum curtum is known ^[2]. In addition, lots from the Gulf of Panama differ in several details from the South American specimens and may belong to other, still unrecognised species, so the identity of the records from the northern part of the range needs confirmation ^[2].

Similar species

• Prunum macleani: The type specimen is much larger; rose-coloured, with the outer lip margined in bright orange and a more elongate body whorl ^[2].

The species is cited from Manta, in Ecuador, southward into temperate waters beyond the Panamic province, with Iquique, in Chile, among the localities of the original description ^[2]. Records from the Gulf of Panama need confirmation ^[2]. Roth notes an analogous situation in the Atlantic: Prunum species present in temperate waters of Argentina ^[2].

Among collection specimens with depth data there are two from Peru: one from the area off Trujillo, taken in 1983 at 6.5 m on sand, and another from Lagunillas beach, in the Paracas National Reserve, taken in 1984 at 1.5 m ^[4]. These are few points and do not allow a depth range to be drawn, but both point to shallow bottoms ^[4].

At Laguna Grande, many fresh shells washed up on an intertidal sandbar were found on 31 March 1972 ^[2]. The source describes beach shells and not living animals, so all it supports is that the species lives on some nearby bottom ^[2].

The sources reviewed say nothing about the diet, reproduction or predators of Prunum curtum. Authors who study the region point out that the marginellid fauna of western South America is understudied, above all the millimetric species, owing to a lack of prospecting, and that up to 2023 only 7 species of the family were tentatively reported from those coasts ^[3].

None of the sources reviewed for this account reports an assessment of its conservation status or concrete threats to the species ^[3]. Boyer and Renda note that since Roth's 1978 publication no further marginellid species had been reported from that coast ^[3].

The most concrete reference in the literature is Laguna Grande, in Ica Province (14° 08' S), where fresh shells were collected on an intertidal sandbar in 1972 ^[2]. These are empty beach shells and not living animals observed, and the source says nothing about access to the site ^[2].

Paita is one of the two localities of the original description of 1832, so it was already associated then with the north coast of Peru; the source does not say at which point, nor whether it can be seen there today ^[2].