Philobrya olstadi

• Main Authors: Urcola, Matias Ricardo, Zelaya, Diego Gabriel
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2024
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Bivalvia; Arcida; Philobryidae; Philobrya; Philobrya olstadi; Antarc*; Antarctic; Antarctic Peninsula; Deception Island
• Online Access: https://doi.org/10.5281/zenodo.10984661; http://treatment.plazi.org/id/A279878B741ED21BF5EAE3B9FEACFD96

Philobrya olstadi (Soot-Ryen, 1951) (Figure 14) Philippiella olstadi Soot-Ryen, 1951: 12, 13, pl. 1, figs. 9, 10; Ageitos de Castellanos 1960: fig. 5. Philobrya quadrata. Melvill & Standen 1907: 124, 145. (Not Philobrya quadrata (Pfeffer, 1886: 119, 120, pl. 4, figs. 6a, b)). Philobrya olstadi. Engl 2012: 47, figs. 5a, b. Type locality: Deception Island, [62°57’S 60°39’W], South Shetland, 75 m. Material examined: Photographs of the holotype (NHM.UIO D 28607). South Orkney: [60°44.3’S 44°44.1’W], intertidal (MACN-In 44469: 16 spec, 1 v); Scotia Bay, [60°46’S 44°40’W], intertidal (NMS Z 1921.143.699: photographs of 1 spec). Antarctic Peninsula: Puerto Melchior, [64°19’S 62°58’W], intertidal (MACN-In 44470: 1 spec, 1 v). Distribution: South Orkney (Engl 2012; this study), South Shetland (Soot-Ryen 1951; Engl 2012; this study), Antarctic Peninsula (Castellanos 1960; this study), and Gough Island? (Dell 1964); intertidal to 75 m. Description: Shell medium-sized (maximum L = 6.2 mm), mytiliform, relatively high ( H/L = 0.82 ± 0.04, n = 16), somewhat inflated ( W/H = 0.74 ± 0, 05, n = 16), moderately solid; with a narrow, ill-defined dorsal slope. Umbos broad, located at anterior end, ventrally directed, slightly (in smaller specimens) to markedly (in larger specimens) projected, bluntly pointed. Umbonal angle: 85‒90° (n = 10). Dorsal margin with the anterior portion long, straight to slightly convex, markedly oblique backwards, and the posterior portion arched to flattened, forming a continuous curve with the posterior margin. Posterior margin evenly arched in smaller specimens, bluntly pointed in larger specimen. Ventral margin nearly straight in small-sized specimens, becoming increasingly concave with growth due to the enlargement of byssal gap. Prodissoconch D-shaped, with posterior end higher than anterior end, widely projected ventrally, of 500‒550 µm Lp (n = 12), separated from the dissoconch by a prominent rim. Postero-dorsal areas poorly defined. Central area smooth in appearance. Dissoconch whitish, ...