Laevilitorina caliginosa (A. Gould, 1849 )

Rosenfeld, Sebastián, Segovia, Nicolás I, Maturana, Claudia S, Aldea, Cristián, Saucède, Thomas, Brickle, Paul, Spencer, Hamish G, Poulin, Elie & González-Wevar, Claudio A, 2023, A revision of the higher latitude periwinkle species Laevilitorina caliginosa sensu lato, Zoological Journal of the Linnean Society 202 (1), pp. 1-18 : 10-13

Laevilitorina caliginosa (A. Gould, 1849)

( Fig. 6 )

Litorina caliginosa – A. Gould, 1849: 83; A. Gould 1852: 198; A. Gould 1856: pl. 14 [sic.], fig. 240.

Laevilitorina caliginosa – von Martens and Pfeffer 1886: 81, pl. 1, fig. 8a–d; Tryon 1887: 254, pl. 46, fig. 29; Melvill and Standen 1907: 130; Strebel 1908: 50; Melvill and Standen 1912: 348; Melvill and Standen 1914: 118; Powell 1951: 107, pl. 1, fig. 26; Guzmán and Ríos 1981: 262; Ríos and Guzmán 1982: 215; Adami and Gordillo 1999: 186; Zelaya 2005: 118, fig. 21; Ojeda et al. 2014: 499; González-Wevar et al. 2022: 7; Rosenfeld et al. 2022: 66, fig. 1a.

Litorina (Laevilitorina) caliginosa – Melvill and Standen 1907: 130; Melvill and Standen 1912: 348.

Paludestrina caliginosa – Rochebrune and Mabille 1889: 42.

Laevilitorina caliginosa – Pelseneer, 1903: 8.

Laevilitorina cf. caliginosa – Dell, 1971: 204.

Laevilitorina caliginosa L5 – González-Wevar et al. 2022: 1527.

Material studied: Puerto Williams, Beagle Channel (− 54.932414°S, − 67.603289°W), n = 50; Lapataia Bay , Beagle Channel (− 54.849706°S, − 68.478319°W), n = 25; Hornos Island, Cape Horn (− 55.967394°S, − 67.218736°W), n = 50; Hookers Point, Falkland/ Malvinas Islands (− 51.700953°S, −57.780369°W), n = 50; Cumberland Bay, South Georgia (−54.283364°S, −36.486956°W), n> 30.

Description

Shell: Small (maximum length 6.48 mm), typical Laevilitorina morphology: fusiform, with rounded to almost convex whorls, suture impressed, concave spire profile, apex blunt. Aperture varies from rounded to ovoid, between 47% and 51% of total H ( Fig. 6A–F ). Macroscopic spiral and axial sculpture absent, but multiple fine growth lines cover the surface of the shell. Columella smooth, inner lip barely reflected over narrow and shallow umbilicus, outer lip thin, simple, and no evidence of thickening. Teleoconch opaque, but last whorl slightly translucent. Significant colour variability among different sites: creamy-white ( Fig. 6C ), brown ( Fig. 6B ), dark brown, or black ( Fig. 6A, D–F ). Small and irregular white spots visible in all analysed specimens. Operculum corneous. Mature H 3.5–6.49 mm. (H/B = 1.25– 1.65, SH = 1.92–2.14) (Supporting Information, Table S5).

Radula: Rachidian: five to seven cusps, central cusp long, rectangular, pointed; first pair of flanking cusps pointed; outer cusps may be present as low, pointed cusps ( Fig. 6G, H ). Lateral: five or six cusps, main cusp being the largest, broadest and rounded, accompanied by two smaller pointed outer cusps and two or three continuously smaller inner cusps ( Fig. 6I ). Inner marginal: seven cusps, main cusp pointed and rectangular, accompanied by one smaller pointed outer cusp and five pointed inner cusps of similar size. Outer marginal: 12–16 thin and short cusps.

Habitat: Rocky intertidal to subtidal shores across the southern tip of South America in the Cape Horn region, including the Beagle Channel, Hornos Islands, Falkland/ Malvinas Islands, and South Georgia, also associated with kelps.

Remarks: Shell shape and coloration are variable among the specimens collected from different localities in southern South America, the Falkland/ Malvinas Islands, and South Georgia. For instance, individuals from Hornos Island collected from crustose algae exhibited creamy-white and brownish green coloration with white spots, mimicking their habitat. In contrast, specimens collected from bare boulders at Puerto Williams and Ushuaia (Beagle Channel) were dark green, brown, grey, and black with white spots. In the original description of the species (A. Gould 1849; see also A. Gould 1852), the specimens presented a shell with a green-brown coloration and an aperture almost 50% of the total height of the shell (A. Gould 1856). This original description is consistent with specimens collected in the area of Cape Horn and the Beagle Channel, near the type locality of Terra del Fuego (A. Gould 1849, 1852; not Kerguelen Island, as reported by Suter 1913, Powell 1951, 1955a, b; 1979). Individuals from these localities were the only ones that exhibited an average LA/H of <50% (0.49 ± 0.01) (Supporting Information, Table S5). Together, the morphological characteristics and the location of collection sites allow us to identify the molecular Laevilitorina L5 lineage as L. caliginosa s.s.

Interestingly, Powell (1951) provided one of the first descriptions of the radular morphology of L. caliginosa , using specimens from South Georgia, and the radula configuration coincides with our observations, especially in the shape of the central rachidian tooth, which is long, rectangular, but with a sharp termination ( Fig. 6H ). In contrast, the central tooth of L. venusta individuals from Kerguelen is rectangular but rounded ( Arnaud and Bandel 1976; this study).

Figures

Figure 6. Laevilitorina caliginosa, Southern South America, South Georgia, and Falkland/Malvinas Islands. Scale bars: 1 mm unless specified otherwise.A–F, specimens of L. caliginosa from: Caleta Paula, Beagle Channel (A); Robalo Bay, Beagle Channel (B); Hornos Island (C); Puerto Williams, Beagle Channel (D); Ushuaia, Beagle Channel (E); and Falkland/Malvinas Islands (F). G–I, radular morphology (SEM), showing a general view (G), rachidian (H), and lateral view (I). J, distribution of L.caliginosa in the southern tip of South America, the Falkland/Malvinas Islands, and South Georgia.