OCCASIONAL PAPERS OF THE California Academy of Sciences No. 72, 6 pages, 4 figures. June 6, 1969 Pyrgupyxis, a New Genus of Diatoms from a South Atlantic Eocene Core By N. Ingram Hendey St. Agnes, Cornwall, England SAN FRANCISCO PUBLISHED BY THE ACADEMY 1969 L I B R A R OCCASIONAL PAPERS OF THE CALIFORNIA ACADEMY OF SCIENCES No. 72, 6 pages, 4 figures. June 6, 1969 Pyrgupyxis, a New Genus of Diatoms from a South Atlantic Eocene Core By N. Ingram Hendey St. Agnes, Cornwall, England In a recent study of some material from a core taken in the South Atlantic Ocean, many siliceous organisms usually referred to the genus Pyxilla were found. The age of the material is Eocene. The core is one of a series taken by personnel of the R. V. Vema on a survey organized and directed by Dr. Maurice Ewing, Director, Lamont Geological Observatory of Columbia University. The pertinent locality information follows: Cruise Core Depth Meters Latitude Longitude Length of Core CAS Number V 18 112 2429 51°40'S. 48°29'W. 260 cm. 41054 The lower portion of the core, 96-260 cm. was described as follows: "Yel- lowish-gray (5Y7/2) moderately sorted, diatomaceous, slightly silty lutite mixed with about 5-7 percent minerals and rock fragments. The lutite contains diatoms and sponge spicules, as the major constituents and a minor amount of Radio- laria." The genus Pyxilla was established by Greville (1865) with the following de- scription: " Pyxilla, n. gen. Grev. Frustules free, oblong, transversely bivalved, box-like, minutely cellulate; each valve terminating in a short, thick apiculus." Two species were described, Pyxilla johnsoniana and Pyxilla barbadensis Greville (1865, p. 2), and illustrated on plate 1, figures 6 and 5. Greville's type specimens are now in the British Museum, P. johnsoniana B.M. 2771 and P. barbadensis B.M. 3037 and an examination of them showed that they are complete cells exactly as illustrated by Greville and that his com- ment that "the globose valve with it's contracted base and terminal apiculus re- sembles the bulbous dome which crowns the minaret of an eastern mosque" is a reasonably accurate description. Pyxilla Greville is therefore seen to be sym- 2 CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers metrical upon the apical axis consisting of two parts each furnished with a cen- tral projection. In the following remarks the two elements of which the cell is composed will be referred to as "parts" not valves, as the latter term has a spe- cific meaning with reference to diatoms. Greville's material came from the Cam- bridge estate Barbados. The type slide B.M. 2771 has only one specimen of P. johnsoniana; fortunately it is a whole cell and no other fragments of Pyxilla are present, though the preparation is a "strewn" slide and contains a large number of other species. The same remarks apply also to slide B.M. 3037. The specimens found in core VIS— 1 12 are of a totally different structure. The South Atlantic core contains a large number of specimens like those re- ferred to Pyxilla by Forti (1909) as P. johnsoniana and P. gracilis. Forti's in- terpretation of Pyxilla has been followed by all authors who have described simi- lar specimens. For convenience the bipartite specimens from core V18-112 are considered to consist of a short cylindrical cuplike element that will be referred to as the lower part and a funnel or trumpet-shaped component that will be referred to as the upper part. The upper part serves as a lid to the cuplike lower element, it is circular in the transapical plane with a convex surface and has its center drawn out to form the hornlike projection that resembles the stem of the funnel. This hornlike projection, usually curved, often increases in width shortly after leaving the surface of the upper part, but narrows again towards the top which is furnished with one or two small apiculi. On the side of the hornlike extension of the upper part is a notch or spur which is the point of attachment of the adjacent cell. The whole cell is punctate-areolate; the upper part being more coarsely marked. The circular face of the lower part is often slightly re- cessed around the margin and the areolae are larger towards the margin decreas- ing in size as they reach the center. In the center the areolae may cover the entire area or may break down to form a few scattered puncta, one or two of which might appear to be more prominent than the others. The puncta are ar- ranged in radiating lines, though in some cells the lower face may show two cen- ters which tend to complicate the radial arrangement. There is no structure pres- ent that corresponds to a girdle in the normal diatom, but often there is a slight constriction showing a hyaline line where the two parts join. Often the cells are found joined together in pairs and from the mode of attachment of similar ends, that is, funnel end to funnel end, it is usually ac- cepted that the cell is a resting spore of a diatom. It is not known for certain which species of diatom produces a particular type of bipartite cell, but fre- quently cells are seen with "fragments" of a thin tubular investment attached which is finely punctate and probably belongs to a Rhizosolenia species. It is not known whether Pyxilla Greville formed pairs as the type slide shows only a solitary specimen, but it is likely that it did not, as no notch or scar of attachment is visible on the short extension of the upper part of the type speci- No. 72] HENDEY: A NEW GENUS OF EOCENE DIATOMS 3 men. In the South Atlantic material many whole cells were found though most occurred as separated parts. It is clear that as the lower part of the South Atlantic specimen does not possess an apiculus or extension, and the upper part with its long hornlike ex- tension, usually curved, and bearing a marginal spur (attachment scar), is so unlike Greville's species, the V18-112 cells cannot be referred to Pyxilla, as Greville's description excludes them. It is proposed therefore that the new genus Pyrgupyxis be established to accommodate the specimens from the core together with similar species which, until now, have been erroneously placed in Pyxilla. Pyrgupyxis Hendey, new genus Cellula cylindrical, parte supera infundibuliformis et apiculis terminalibus instructa. Pars infera, brevis cylindrical, cupulata. Superficies valvarum areolata. Cellulae in paribus extremis similibus conjunctae. Cell cylindrical, with the upper part shaped like a funnel and furnished with terminal spines. Lower part short, cylindrical, cuplike. Surface of the parts areolate. Cells united in pairs by similar ends. Pyrgus — a tower, pyxis — a box. Pyrgupyxis eocena Hendey, new species. (Figures 1-4) Cellula cylindrical, in daubus partibus formata. Pars supera ad instar infundibuli et apiculis terminalibus instructa. Pars infera brevis cylindrical, cupulata. Superfies partium areolata, areolae in parte infera in striis radiantibus dispositae. Mensura cellularum: Long. 70-80 microns; lat. 35-40 microns. Hab. In medio ex solo maris in Oceano Atlantico. Cell cylindrical. Formed in two parts. Upper part in the form of a funnel and furnished with terminal spines. Lower part short cylindrical, cuplike. Sur- face of the parts areolate, areolae on the lower part arranged in radiating striae. Dimensions of the cells length 70-80 microns, breadth 35-40 microns. Habitat. In a core from the sea floor in the Atlantic Ocean. Holotype no. 3959 (CAS) from Locality 41054, lat. 51°40'S.; long. 48° 29'W.; Lamont Geological Observatory no. R. V. Vema Cruise 18, core 112, depth 2429 M. Eocene. The Eocene age has been readily determined by com- parison of other species of diatoms and Silicoflagellata associated with this Pyrgupyxis at such well known localities as Barbados, West Indies, Oamaru, New Zealand, Mors Denmark, and Kreyenhagen Shale of California. The lower cuplike portion of the diatom has a deep mantle with straight sides and the areolae are in quinquux. CALIFORNIA ACADEMY OF SCIENCES [Occ. Papers C-^ii.0 ---T^-c^-'-1-' ~-,c c^¥n? - c- ?c -„ ■ - I — —-a.^^'^, ■-—urn -• • •■.••■ ~^a L ? . ■-. ' , „ W V - ' - Vi -\ r fX'?rf.o - : C - ■ -ir ' - ■ - Figures 1-4. Pyrgupyxis eocena Hendey, new pjenus, new species. Approximate magnifi- cation, X 1000. The lower surface is convex and slightly invaginated at the margin. The sur- face is punctate-areolate, with the areolae larger at the margin than at the cen- ter which may be entirely areolate or the areolae may be reduced to a few scat- tered puncta. The upper part is convex, with no definite mantle at the margin, and the center is drawn out or produced to form a hornlike structure, usually slightly curved, and bearing a notch or spur on one side which is the point of attachment of the contiguous cell. The upper part is like a funnel where the stem of the funnel is about the same length as the diameter of the wider cuplike end. The distal end of the upper part usually carries two small terminal apiculi. The surface of the upper part is areolate with the areolae larger at the broader end and reduced in size as they proceed up the produced or stemlike No. 72] HENDEY: A NEW GENUS OF EOCENE DIATOMS 5 portion, at the distal end of which the puncta are few and small. The diameter of the lower cuplike end is greater than the depth of the cup. Pyrgu pyxis coccna was common in the VI 8 112 material. Other described species of Pyrgu pyxis include the following: Pyrgupyxis johnsoniana — Pyxilla johnsoniana in Forti (1909), non Pyxilla johnsoniana Greville (1865). Pyrgupyxis johnsoniana var. intermedia = Pyxilla johnsoniana var. intermedia Tempere et Forti in Forti (1909). Pyrgupyxis gracilis = Pyxilla gracilis Tempere et Forti in Forti (1909). Pyrgupyxis gracilis var. buccinalis — Pyxilla gracilis var. buccinalis Forti in Forti (1909). Pyrgupyxis gracilis var. saratoviana — Pyxilla gracilis var. saratoviana Tempere et Forti in Forti (1909). Pyrgupyxis caput— avis — Pyxilla C a put-Avis J. Brun in Forti (1909). Pyrgupyxis caput-avis var. gracilis — Pyxilla Caput-Avis var. gracilis Tempere in Forti (1909). Pyrgupyxis prolongata (J. Brun) = Pyxilla prolongate J. Brun in Forti (1909). Other species of Pyrgupyxis from the V18-112 and other cores are being studied. REFERENCES Forti, A. 1908. Studi per una monografia del genere Pyxilla (Diatomee) e dei generi affini. La Nuova Notarisia, series 20, fasc. 1, pp. 19-38, 2 pis. Tissued January, 1909]. Greville, R. K. 1865. Descriptions of new and rare diatoms. Series XIV. Transactions of the Micro- scopical Society of London, vol. 13, pp. 1-10, pis. 1, 2. '.""I I IHHAHV WH ITFIiJ K