OCCASIONAL PAPERS OF THE California Academy of Sciences No. 69, 11 pages, 12 figures. September 25, 1968 Balanus hopkinsi. New Species, and B. balanus (Linnaeus, 1758) (Cirripedia, Thoracica) from Plio-Pleistocene Sediments on Tjornes, Northern Iceland By Victor A. ZuUo California Academy of Sciences SAN FRANCISCO PUBLISHED BY THE ACADEMY 1968 OCCASIONAL PAPERS OF THE CALIFORNIA ACADEMY OF SCIENCES No, 69, 11 pages, 12 figures. September 25, H)G8 Balanus hopkinsi. New Species, and B. balanus (Linnaeus, 1758) (Cirripedia, Thoracica) from Plio-Pleistocene Sediments on Tjornes, Northern Iceland By Victor A. Zullo California Academy of Sciences Abstract: Balanus (Balanus) hopkinsi, a new species bearing close resemblance to B. eburneus Gould, 1841, occurs in the Tjornes sediments of late Pliocene or earliest Pleistocene age on Tjornes, northern Iceland, where it is associated with a temperate Atlantic molluscan fauna. The overlying early Pleistocene Breidavik sediments con- tain the boreo-arctic barnacle B. (B.) balanus (Linnaeus, 1758) in association with extant molluscs of a colder water aspect. Introduction A collection of barnacles made in the course of a re-study of the Pliocene and Pleistocene sediments of Tjornes in northern Iceland (fig. 1) by Thorleifur Einarsson, Icelandic University Research Institute and David M. Hopkins, United States Geological Survey, Menlo Park, California, includes a new species of Balanus {Balanus) and B. balanus (Linnaeus, 1758). The species are mutually exclusive in their stratigraphic distribution throughout the sequence (fig. 2). Balanus balanus, an extant boreo-arctic barnacle, occurs in the Breidavik sediments of early Pleistocene age together with a molluscan fauna characterized by species of Pacific ancestry and cold water aspect. The new species occurs in the stratigraphically lower Tjornes sediments of late Pliocene or earliest Pleistocene age. These deposits are below the earliest indication of glaciation in the sequence (2.4-3.0 million years ago) and contain a number of CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers Figure 1. Map of barnacle localities on Tjorncs peninsula, northern Iceland. Inset indicates location of Tjornes (Tj) and Snaefcllsnes (Sn) in Iceland. -> Figure 2. Part of Tjorncs sequence illustrating slratiRraphic distribution of Balanus balanus (Q) and B. hopkinsi (X) (modified after Einarsson ct al., 1967). No. 70] ZULLO: SOME BARNACLES FROM ICELAND r—O o Z3 (D (/) (A — 500 "—900 B r e i d a V I k F u r u V f k beds I ava f I ows T j 6 r n e s beds )-o First indication of glaciation Appearance of Pacific boreal molluscs X X X X :alifornia academy of sciences [Occ. Papers molluscs whose northern limits are now to the south (Hopkins et al., 1965; Einarsson et al., 1967). This new species is described as follows: Balanus (Balanus) hopkinsi Zullo, new species. (Figures 3-10.) Diagnosis. Smooth walled, conic Balanus strict sense, with broad radii, transversely septate parietal and basal tubes, strongly arched scutum with external longitudinal striae, and trident shaped tergum with long, narrow, pointed spur. Description. Shell (figs. 9-10) high conic to tulipiform, strongly bent towards short, acutely concave carina; orifice diamond shaped, toothed, as broad or broader than base; parietes smooth, with numerous ovate longi- tudinal tubes crossed throughout by closely spaced transverse septa; radii broad with denticulate sutural edges and oblique summits that make about a 45° angle with direction of growth; alae broad with less oblique summits; interior sharply ribbed below sheath; basis calcareous, with transversely septate tubes. Scutum (figs. 5, 7, 8) strongly warped between base and apex; exterior with conspicuous growth ridges crossed by fine, but obvious longitudinal striae; striae best developed over narrow, pigmented longitudinal bands sometimes present on lower two-thirds of scuta (fig. 8); adductor ridge short, straight, erect, placed about midway between articular ridge and occludent margin; upper end of adductor ridge higher than and not confluent with or approaching articular ridge; articular ridge broad, one-half to two-thirds length of tergal margin, reflexed; no depres.sor muscle pit observed. Tergum (figs. 3, 4, 6) trident shaped, flat; carinal side of basal margin with deep, V-shaped notch; scutal side similarly, but less deeply notched; tergal spur long, narrow, about one-fifth width of basal margin, and terminating in acute point on scutal side; depressor muscle crests well developed on carinal lobe. Measurements ParatypeUSNM 161401 Paratype USNM 161403 (conic) ParatypeUSNM 161402 (tulipiform) about Occurrence. Specimens of B. hopkinsi were collected at the following six localities in the Tjornes sediments (after Hopkins, personal communication, 1964): 475B Bed A of Bardarson (1925). Landslide block on south bank (Type Locality) of the mouth of Kaldakvisl, representing the lowest bed in lateral carinorostral rostral diameter diameter height 17 mm. 19.4 mm. 18.7 mm 14 mm. 15 mm. 21.1 mm 10 mm. 13 mm. 31 mm. No. 70] ZULLO: SOME BARNACLES FROM ICELAND 6 7 8 Figures 3-8. Balaniis (Balanus) hopkinsi Zullo, new species. (3) Tergal interior, (4)' tergal exterior, (5) scutal interior, Holotype (USNM cat. no. 161398; loc. 475B), height of tergum 8.5 mm; (6) tergal exterior, (8) scutal exterior, Paratype (USNM cat. no. 161399; loc. 475B), height of tergum 8.2 mm; (7) scutal exterior, Paratype (USNM cat. no. 161400; loc. 48SB), height of scutum 9.5 mm. 6 CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers the Tjornes sediments, resting unconformably on Tertiary basalts, 66° 86.3' N, 17° 17.5' W. 438E Balanus horizon supposedly at top of Bed 7, but because of landsliding possibly part of Bed 8, Lindarlaekjarfoss, 66° 07.1' N, 17° 15.9' W. 437 Base of Bed 8, just above coal bed D, swale halfway between Lindarlaekur and mouth of Reka. 488B Bed 9, west end of cutbank on north side of Skeifa, just upstream from road, 66° 07.7' N, 17° 14.0' W. 440B Bed 9, between Skeifarfoss and Brunngil, 66° 07.5' N, 17° 16.0' W. 441B Middle and upper part of Bed 10, Stollen, 66° 07.9' N, 17° 15.9' W to 66° 08.25' N, 17° 15.8' W. Disposition of type material. Holotype and paratypes deposited in the U. S. National Museum, Washington, D. C. Holotype USNM cat. no. 161398 and paratypes USNM cat. nos. 161399, 161402, 161403 from locaUty 475B. Paratype USNM cat. no. 161401 from locality 440 B. Paratype USNM cat. no. 161400 from locality 488B. Remarks: Balanus hopkinsi is similar and no doubt closely related to the extant western North Atlantic species B. eburncus Gould, 1841 that ranges from Rio de Janeiro north into Massachusetts. The new species can, however, be readily distinguished through comparison of the opercular valves. The scutum of B. eburncus is nearly flat and strongly striate longitudinally, whereas that of B. hopkinsi is markedly arched and the striae, although distinct, are less deeply incised in all specimens examined. The adductor ridge of the scutum is also differently placed in the two species. In B. eburncus the apical end nears or is confluent with the basal end of the articular ridge, but in B. hopkinsi the adductor ridge is removed from the articular ridge and apically terminates higher on the scutum. The tergal spurs are quite different. That of B. eburncus is relatively short, broad, and is basally truncate, whereas the new species has a longer, narrower spur that is pointed basally. The shell and terga of the West African species B. pallidus Darwin, 1854 (including B. pallidus stutsburi Darwin, 1854) are somewhat similar to those of B. hopkinsi, but the scuta of the former lack longitudinal striae. Balanus (Balanus) balanus (Linnaeus). (Figures 11, 12.) Balanus balanus occurs in glacial deposits of the upper part of the Breidavik sediment sequence on Tjornes and the lower part of the Bulandshofdi sediment sequence of Snaefellsnes, western Iceland (fig. 1). These deposits are strati- graphically higher than the rocks containing B. hopkinsi and succeed an No. 70J ZULLO: SOME BARNACLES FROM ICELAND j ^^s^^^-^i^ps 1 ^^^^^B 1 ^^^^■^B^^F^ « ^^^HKi^ Mjl^ii^^^^^H KJ l^^HHi ^I^^^^H 12 Figures 9-10. Balanus (Balanus) hopkinsi Zullo, new species. (9) Hiph conic shell, Paratype (USNM cat. no. 161401; loc. 440B), height 17.5 mm; (10) tulipiform shell, Para- type (USNM cat. no. 161402; loc. 475B), height 31.4 mm. Figures 11-12. Balanus (Balanus) balanus (Linnaeus). (11) Shell, Hypotype (USNM cat. no. 161405; loc. 426B), carinorostral diameter 15.2 mm; (12) basis on rock, Hypotype (USNM cat. no. 161404; loc. 43SB), greatest diameter 29.3 mm. influx of boreal molluscs of Pacific origin. Remains of this barnacle were obtained from the following eight localities in Iceland: Breidavik sediments, Tjornes 43 2 B From scree blocks on beach derived from Beds 12 and 14 near Torfholl, 66° 12.0' N, 17° 09.0' W. 430B Scree block probably derived from base of Bed 14, but pos- sibly from Bed 12. On beach at Torfholl, 66° 12.0' N, 17° 09.0' W. 8 CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers 432F From 1 m of Bed 14, Torfholl, 66° 12.0' N, 17° 09.0' W. 426B Conglomerate bed at base of Bed 12 just north of Svarthamar, 66° 11.7' N, 17° 08.7' W. 435B Same locality as 426 B. 422C Bed 9 in shore cliffs between Trollagil and Svarthamar, 66° 11.3' N, 17° 09.5' W. 425B Bed 8b at Svarthamar, 66° 11.5' N, 17° 09.0' W. Bulandshojdi sediments, Snaejellsnes 53 6B Bulandsgil sediments exposed in dry waterfall back of small electric power plant at Olafsvik. Specimens are from upper and lower claystone, in iceberg sediment formed near icefront, 64° 53.3' N, 23° 42.0' W. Extant B. balanus is a boreo-arctic species ranging from 80° North latitude to Long Island Sound and the English Channel in the Atlantic, and Puget Sound and the Kurile Islands in the Pacific, from the lower intertidal (in northern waters) to about 300 m depth (Broch, 1924; Pilsbry, 1916). This species {= B. porcatus of authors) has been reported from several Pleistocene localities in northern Europe and North America, including the Red and Mammaliferous Crags of England, the glacial deposits of Udevalla, Sweden, Skien, Norway, Island of Bute, Scotland, and eastern Canada (Darwin, 1854), Spitzbergen and Greenland (vide Feyling-Hanssen, 1953), and late Pleistocene terrace deposits in Oregon and glacio-marine sediments in southeastern Alaska (Zullo, 1966). Balanus balanus was previously reported from the Pleistocene of western Iceland by Bardarson (1921) together with B. crenatus Bruguiere, 1789 and Balanus species. The numerous Tertiary reports of B. balanus from Europe are open to question. Kolosvary (1955, p. 184) listed it from the Miocene of Italy, England, France, Germany, the USSR, Belgium, and Sweden, and Davadie (1963, p. 69), in repeating these localities, stated that this species is common in the Pliocene of Italy and Sicily and abundant in the lower Helvetian of France. Kolosvary's list of Miocene localities must in part be a typographical error, for there are no known marine deposits of definite Miocene age in England. This record, together with that from Sweden, probably was meant to refer to Darwin's (1854) Pleistocene localities. Few of the Tertiary specimens referred to B. balanus have been illustrated, and the only ones to come to my attention (those of Alessandri, 1906, pi. 17, figs. 16-17, and Menesini, 1966, pi. 26, figs. 3-7) from the Miocene and Pliocene of Italy are definitely not of that species. It is quite possible that most, if not all of the Tertiary identifications of B. balanus are incorrect. Certainly Miocene hydroclimates of Europe were quite warmer than the boreo-arctic waters to which extant B. balanus is re- stricted. Hence, if the Miocene records were assumed to be correct, it would No. 70] ZVLLO: SOME BARNACLES FROM ICELAND 9 force the conclusion that this species had lived first under one, then another set of climatic conditions, had markedly altered its physiological tolerances to meet these climatic changes, but had maintained its morphological identity. In view of this seemingly untenable set of circumstances, it is suggested that a more critical examination be made of the Tertiary barnacles assigned to B. balarms. ZOOGEOGRAPHIC IMPLICATIONS The distribution of barnacles in the sequence on Tjornes follows the paleo- climatic and zoogeographic conclusions presented by Einarsson et al. (1967). Balanus hopkinsi occurs exclusively in the lowest "Tapes" zone and the middle "Mactra" zone which are typified by shallow water and littoral sediments intercalated with thin lignite seams and lacustrine beds. The molluscs of these zones are primarily Atlantic in character, but include a few warm water species of Pacific origin that are postulated to have taken advantage of a Miocene opening of the Bering land bridge to migrate via the northern Arctic route. This molluscan fauna and the pollen flora of the lignites suggest a milder temperate climate than is present in Iceland today. The upper "Cardium" zone of the Tjornes sediments is characterized by an influx of boreal molluscs of Pacific origin and a corresponding elimination of the species typical of the lower zones. The first indications of glaciation in the Tjornes sequence (2.4-3.0 million years ago) are found in the Furuvik beds which consist of a sequence of marine and glacio-marine sediments inter- bedded in the lavas separating the Tjornes and Breidavik sediments. No barnacles were collected either from the "Cardium" zone or the Furuvik beds, but the modern boreo-arctic species B. balanus was obtained from the strati- graphically higher Breidavik sediments. These sediments are composed of interbedded lavas and glacial deposits that contain a modern boreo-arctic mol- luscan fauna. It is impossible at present to determine whether B. hopkinsi is part of the ancestral stock group of extent B. eburneus or a diversification from B. eburneus itself. Fossils ascribed to B. eburneus are few {e.g., Pilsbry, 1918, 1924) and being based on shells alone, are not conclusive. It is possible to hypothesize that B. hopkinsi was of Atlantic origin and was eliminated from northern Iceland by the cooling of marine hydroclimates preceding glaciation. If the Tertiary European records of B. balanus can be ignored, it is tempting to suggest that this species was part of the major invasion of Pacific marine invertebrates into the boreal Atlantic during the periodic Pleistocene inundations of Bering land bridge. However, the Pacific fossil record of B. balanus is scanty and undiagnostic, and although it has a potential ancestor in the Pacific B. rostratus Hoek, 1883 stock, much more information is needed before any conclusion can be made concerning the origin of B. balanus. 10 CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers Acknowledgments I wish to thank Drs. David M. Hopkins and Thorleifur Einarsson for providing the specimens used in this study, and for their advice during the preparation of the manuscript. REFERENCES CITED Alessandri, G. de 1906. Studi monographici sui Cirripedi fossili d'ltalia. Palaeontographia Italica, vol. 12, pp. 207-324, figs. 1-9, pis. 13-18. B.^RDARSON, G. 1921. Fossile Skalaflejringer ved Breidifjordur i Vest-Island. Geologiska Foreningens i Stockholm, Forhandlingar, Bd. 43, Haft 5, no. 346, pp. 323-380, figs. 1-S. 1925. A stratigraphical survey of the Pliocene deposits at Tjornes, in northern Iceland. Danske Videnskabernes Selskab, Biologiske Meddelelser, Bd. 4, no. 5, pp. 1-118, figs. 1-14, pis. 1-2. Broch, H. 1924. Cirripedia Thoracica von Norwegen und dem Norwegischen Nordmeere. Viden- skapsselskapets Skrifter, 1. Klasse 1924, no. 17, pp. 1-121, figs. 1-35. Darwin, C. 1854. A monograph on the sub-class Cirripedia: Balanidae, Verrucidae. Ray Society, London, 684 pp., 11 figs., 30 pis. Davadie, C. 1963. Etude des balanes d'Europe et d'Afrique. Editions du Centre National de la Recherche Scientifique, Paris, 146 pp., 57 figs., 55 pis. EiN.'\RSSON, Th., D. M. Hopkins, and R. R. Doell 1967. The stratigraphy of Tjornes, northern Iceland, and the history of the Bering Land Bridge, in The Bering Land Bridge (edited by D. M. Hopkins). Stanford University Press, Stanford, California, pp. 312-325, figs. 1-2. Feyling-Hanssen, R. W. 1953. The barnacle Balanus balanoides (Linnc, 1766) in Spitzbergen. Norsk Polarin- stitutt Skrifter, nr. 98, pp. 1-64, figs. 1-13, pis. 1-9. Hopkins, D. M., Th. Einarsson, and R. R. Doell 1965. The stratigraphy of Tjornes, northeastern Iceland: its significance for the history of the Bering Land Bridge. International Association for Quaternary Research, 7th International Congress, Abstracts, p. 223. Kolosvary, G. 1955. tjber stratigraphischer rolle der fossilen Balaniden. Acta Biologica, Acta Uni- versitatis Szegediensis, nova series, vol. 1, fasc. 1-4, pp. 183-188. Menesini, E. 1966. I balani Miocenici delle "Arcnarie di Ponsano" (Volterra, Provincia di Pisa). Palaeontographia Italica, vol. 60, pp. 99-129, fig. 1, pis. 25-31. PiLSBRY, H. A. 1916. The sessile barnacles (Cirripedia) contained in the collections of the U. S. Na- tional Museum; including a monograph of the American species. United States National Museum, Bulletin 93, pp. i-xi, 1-366, figs. 1-99, pis. 1-76. 1919. Cirripedia from the Panama Canal Zone. United States National Museum, Bulletin 103, pp. 185-188, pi. 67. No. 70] ZULLO: SOME BARNACLES FROM ICELAND 11 1924. Miocene and Pleistocene Cirripedia from Haiti. Proceedings of the United States National Museum, vol. 65, no. 2S15, pp. 1-3, pi. 1. ZULLO, V. 1966. Zoogeographic affinities of the Balanomorpha (Cirripedia: Thoracica) of the Eastern Pacific in The Galapagos (edited by R. I. Bowman). University of California Press, Berkeley & Los Angeles, California, pp. 139-144, fig. 1. til iimiifiKiiiiMiiii mill III iiKi nil I