Oscilla virginiae Penas , Rolan & Sabelli, 2020

Albano, Paolo G., Steger, Jan, Bakker, Piet A. J., Bogi, Cesare, Bosnjak, Marija, Guy-Haim, Tamar, Huseyinoglu, Mehmet Fatih, LaFollette, Patrick I., Lubinevsky, Hadas, Mulas, Martina, Stockinger, Martina, Azzarone, Michele & Sabelli, Bruno, 2021, Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification, ZooKeys 1010, pp. 1-95 : 1

Oscilla virginiae Penas, Rolan & Sabelli, 2020 Figure 25A, B

New records.

Israel • 1 spcm; west of Rosh HaNikra Islands; 33.0704°N, 35.0926°E; depth 12 m; 29 Oct. 2018; rocky substrate; suction sampler; HELM project (sample S52_1F) • 1 spcm; west of Rosh HaNikra Islands; 33.0725°N, 35.0923°E; depth 19 m; 29 Oct. 2018; rocky substrate; suction sampler; HELM project (sample S53_1F); size: H 1.6 mm, W 0.9 mm (illustrated specimen).

Additional material examined.

Oscilla appeliusi (Hornung & Mermod, 1925): EGYPT • 1 sh; Sinai (Red Sea), south of Sharm-el-Sheik, Na’ama Bay; 27.8500°N, 34.2833°E; depth 0-6 m; 28 Sep. -4 Oct. 1978; rocky substrate; A.J. Ferreira leg.; LACM 1978-79.4 • 1 sh; Sinai (Red Sea), Gulf of Aqaba, Strait of Tiran, Jackson Reef; 28.0167°N, 34.4667°E; depth 2-3 m; 31 Oct. 1985; sand and coral substrate; T. Bratcher leg.; LACM 1985-111.5 • 2 shs; Sinai (Red Sea), Gulf of Aqaba, Strait of Tiran, east side Jackson Reef; 28.000°N, 34.4667°E; depth 10 m; 9 Jul. 1988; coral rubble; J. H. Golden leg.; LACM 1988-118.1 • 4 shs; Sinai (Red Sea), off Ras Umm Sid, “Amphoras” dive site; 27.8667°N, 34.333°E; depth 18 m; 24 Jul. 1988; coral rubble; J.H. Golden leg.; LACM 1988-119.2.

Indonesia • 7 shs; Papua Province, south-east of Biak Island, east side of Auki Islet; 1.2300° S, 136.3367°E; depth 0 m; 5 Apr. 1988; rock; J.H. McLean & E. Abbott leg.; LACM 1988-48.12.

Taiwan • 7 shs; Tai-Pei County, east of Chi-lung (= Keelung), south-east side of Pitou Chiao (= Pitou Nonkow); 25.1333°N, 121.9167°E; depth 0-3 m; 10 May 1988; rocky tide pool; C.C. Coney & P.F. Liu leg.; LACM 1988-80.13.

Miralda sp. ( Oscilla jocosa sensu van Aartsen et al. (1989)): Israel • 1 spcm; west of Rosh HaNikra Islands; 33.0704°N, 35.0926°E; depth 12 m; 29 Oct. 2018; rocky substrate; suction sampler; HELM project (sample S52_1F); size: H 2.0 mm, W 1.0 mm (illustrated specimen).

Remarks.

Oscilla virginiae is characterized by a small-sized, white, conical shell with a type A protoconch. The sculpture consists of thick, smooth spiral cords: the first and second whorl bear two cords; the upper cord is broadest and bifurcates on the third whorl, forming three cords on the last whorl, with the newly formed pair remaining positioned very close one to each other (Figure 25A, B ; Peñas et al., 2020).

This species has just been described from the infralittoral of Jordan and also occurs in the Egyptian Red Sea ( Peñas et al. 2020). It superficially resembles the Indo-Pacific O. appeliusi (Hornung & Mermod, 1925), and indeed, a juvenile shell from Dahab (Egypt) was recently figured by Blatterer (2019: plate 212, fig. 17c, d) under this name. In contrast to O. virginiae , however, O. appeliusi bears spiral cords more similar in thickness which are spaced more equidistantly and closer to each other. Already on the second whorl, three cords are present, and the uppermost cord does not evidently bifurcate ( Peñas et al. 2020). Lastly, the illustration of Hornung and Mermod (1925) suggests a greater number of spiral cords on the last whorl. To date, O. appeliusi has not been recorded from the Mediterranean Sea.

Within the Mediterranean, O. virginiae is superficially similar only to two other non-indigenous pyramidellids, Cingulina isseli (Tryon, 1886) and Miralda sp. (Figure 25C, D ). The latter taxon has previously been reported under the name Oscilla jocosa Melvill, 1904, despite recent evidence by Peñas & Rolán (2017) that it is not conspecific with Melvill’s (1904) type material. Oscilla virginiae differs from C. isseli by its broader, more conical shell, fewer whorls, smaller size ( C. isseli reaches a height of ~ 3 mm), and the much less pronounced axial sculpture between the spiral cords. Compared to Miralda sp., O. virginiae differs by its smaller size (up to ~ 3 mm in Miralda sp.), the absence of beads on the two upper spiral cords (Figure 25C, D ), and stronger spiral cords on the base of the shell. Another Oscilla present in the Mediterranean Sea is O. galilae Bogi, Kharan & Yokes, 2012, which can be easily distinguished from O. virginiae by the smaller size, the oval profile, the oblique spiral sculpture, the more prominent axial sculpture and a type C protoconch. Peñas et al. (2020) illustrated O. galilae (their Fig. 38A-E ) under the name O. cylindrica (de Folin, 1879) suggesting synonymy between the two names. However, O. cylindrica can be easily distinguished from O. galilae because it bears spiral cords without interspaces, because it does not bear the fine axial lamellae typical of O. galilae and because of its more cylindrical profile. The Red Sea records of O. virginiae and O. galilae by Peñas et al. enable to assess that both species are non-indigenous in the Mediterranean Sea.

Figures

Figure 25. Comparison between Oscilla virginiae Penas, Rolan & Sabelli, 2020 and Miralda sp. A, B Oscilla virginiae, west of Rosh HaNikra Islands, Israel, HELM project (sample S 53 _ 1 F): front (A) and back (B) views C, D Miralda sp. (Oscilla jocosa sensu van Aartsen et al. (1989)), west of Rosh HaNikra Islands, Israel, HELM project (sample S 52 _ 1 F): front (C) and back (D) views. Scale bars: 0.5 mm.

Figure 38. Pegophysema cf. philippiana (Reeve, 1850), Palmachim, Israel, Shafdan project (sample 24 (B )): right valve outer (A) and dorsal (B) views. The pink hue is due to staining with eosin solution. Photograph courtesy S. Bartolini. Scale bar: 5 mm.