Entogoniopsis novazealandica (Grove & Sturt) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams, 2015

Witkowski, Jakub, Sims, Patricia A., Strelnikova, Nina I. & Williams, David M., 2015, Entogoniopsis gen. nov. and Trilamina gen. nov. (Bacillariophyta): a survey of multipolar pseudocellate diatoms with internal costae, including comments on the genus Sheshukovia Gleser, Phytotaxa 209 (1), pp. 448-450 : 448-450

5. Entogoniopsis novazealandica (Grove & Sturt) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams ,

comb. nov. et stat. nov.

(SEM: Figs 69–75 ; LM: Figs 76–81 , see also Figs 85–86 )

ENTOGONIOPSIS GEN. NOV. AND TRILAMINA GEN. NOV. (BACILLARIOPHYTA)

Phytotaxa 209 (1) © 2015 Magnolia Press • 15

BASIONYM: Triceratium (‘Dobreèanum’) dobreeanum var. (‘ nova Zealandica ’) novazealandica Grove & Sturt (1886 , Journal of the Quekett Microscopical Club Series 2(2): 328, pl. XIX, figs 17–18).

TYPE (here designated):—‘ Oamaru , Otago, New Zealand’ (BM71533, lectotype! = Fig. 77 ) .

Triceratium Novae Seelandiae (Grove & Sturt) A.W.F. Schmidt (1888 : taf. 127, figs 5–8).

‘ Biddulphia dobreana var. novae-seelandiae (Grove & Sturt)’ [sic] sensu Hanna & Grant (1926: 133), nom. invalid.

Trigonium dobreeanum var. novaeseelandiae (Grove & Sturt) Hustedt (1959a : taf. 470, figs 2, 4–6).

Frustules subrectangular in girdle view ( Fig. 77 ), valves tripolar with straight or slightly concave sides and acute to slightly rounded poles ( Figs 76, 78–81 ). A distinct, circular depressed area is located in the valve face centre ( Figs 69, 72 ). Otherwise, the pattern of valve face undulations is variable, with the area adjacent to the central depression either approximately flat ( Fig. 69 ) or raised ( Fig. 72 ). Stout elevations bearing pseudocelli at the summits are located at the poles ( Figs 69–70, 72–73 ). The polar elevations are sometimes slightly offset from the valve face margin toward the centre ( Figs 69 versus 73). Within the central depression, there are large, scattered poroid areolae in the central part, and few irregular rows of areolae closer to the margin ( Figs 76, 78–81 ). Outside the central depression, areolae are aligned in radial rows ( Figs 76, 78–81 ). Mantle is shallow, steeply downturned ( Fig. 73 ), with a smooth, hyaline margin, slightly expanded inward ( Fig. 71 ). Mantle areolation is highly variable, with some specimens having regular rows of poroid areolae parallel to the pervalvar axis ( Figs 69, 71 ), whereas others have sparse poroid areolae arranged in rows or scattered at various levels on the mantle ( Fig. 73 ). Prominent internal costae form a variable pattern on the valve interior ( Figs 71 , 76, 78–81 ): a transverse costa extending between two adjacent sides next to each pole is usually present ( Fig. 71 ), and series of shorter, radially oriented costae that reach to the margin of the central depression are distributed along each side, between the transverse costae ( Figs 76, 78–81 ). All costae continue down the mantle and merge with the expanded hyaline mantle margin ( Fig. 71 ). Valvocopula attaches to the internal costae by means of small clasping devices ( Figs 74–75 ), and to the expanded mantle margin, by means of a fossa ( Fig. 75 ). Valvocopula is closed, deeper than the mantle, and perforated by alternating rows of poroid areolae parallel to the pervalvar axis ( Figs 74, 75 , 77 ). Measurements (n =17): average side length: 123.7–334.5 µm; 2–3 areolae in 10 µm in the marginal zone and 2–2.5 areolae in 10 µm within the central depression; 1–2 costae in 10 µm, measured along the valve face margin; central depression diameter: 32% of average side length (±15.5%).

Typification: A strewn slide in the Saxton collection (BM71533), prepared by Grove and annotated with MF coordinates (31|14), includes a specimen of E. novazealandica in girdle view ( Fig. 77 ). The slide label reads ‘ T. dobr . F.V.’ (i.e., girdle view). Based on the high overall resemblance of this specimen to the one illustrated in Grove & Sturt (1886: pl. XIX, fig. 18) and reproduced here ( Fig. 86 ), we designate slide BM71533 as the lectotype of E. novazealandica .

Geographic and stratigraphic distribution ( Fig. 10, sites 18–19):

(a) specimens:

Late Eocene: South Tasman Rise, Southwestern Pacific Ocean: DSDP Site 281, core-section 281-15: SZCZ 15073, 22056–22057.

Late Eocene-earliest Oligocene: Oamaru , Otago, New Zealand: BM stubs P.1274 ( Figs 70, 72–75 ) and P.1277 ( Figs 69, 71 ), BM46550, BM46561, BM46575 ( Fig. 81 ), BM46607 ( Fig. 78 ), BM61050, BM63524 ( Fig. 76 ), BM71533 ( Fig. 77 , lectotype), BM coll. Adams: F1295, G93, G659 ( Fig. 80 ). Oamaru Diatomite outcrop at Jackson’s Paddock: BM coll. Adams G116 ( Fig. 79 ).

(b) records:

Late Eocene-earliest Oligocene: Oamaru , Otago, New Zealand: Schmidt (1888: taf. 127, figs 5–8, 1891: taf. 168, fig. 2); Laporte & Lefébure (1929: pl. XIV, fig. 99); Hustedt (1959a: taf. 470, figs 2, 4–6); Oamaru Diatomite outcrops at Cormack’s Siding: Grove & Sturt (1886: 328, pl. XIX, figs 17–18), De Lautour (1888: 310, pl. XXI, fig. 4), Desikachary & Sreelatha (1989: 274); Bain’s Farm, Bain’s Lower, Cormack’s Top, Division Hill, Forrester’s Hill, Jackson’s Paddock, Mavor’s, William’s Bluff: Desikachary & Sreelatha (1989: 274–275).

Observations: — Entogoniopsis novazealandica has a complicated nomenclatural history including many orthographic variations as well as an evolving taxonomic concept with respect to biddulphioid diatoms. Grove & Sturt tentatively proposed their specimens to be a variety of Triceratium dobreeanum Norman ex Greville (1865a: 6 , pl. II, figs 23–24, reproduced here in Figs. 82–83 ; Grove & Sturt 1886: 328, pl. XIX, figs 17–18, reproduced here in Figs 85–86 ). Grove & Sturt (1886) remarked that their specimens were more densely areolated and had lower polar elevations than Greville’s T. dobreeanum . The line drawing in Greville (1865a), however, reveals another significant difference: the presence of broken linking spines at the summits of the polar elevations in T. dobreeanum . Examination of the holotype specimen of T. dobreeanum (BM3340; Fig. 84 ) reveals a fractured valve with an attached valvocopula, mounted in girdle view. Both the structure of the valvocopula and the valve resemble

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E. novazealandica . However, the holotype confirms the presence of damaged linking spines at the summits of the slender polar elevations, alongside the pseudocelli. Species in Entogoniopsis generally lack linking spines, except for one unnamed species (reported here as Entogoniopsis ? sp. 1, below). The considerable variability in valve face undulations observed in E. novazealandica suggests that this species may have been heterovalvar. Based on the currently available evidence, however, the heterovalvy with respect to the presence or absence of linking spines cannot be verified. Finally, Greville (1865a) reported T. dobreeanum from dredged material of unknown age, and therefore we cannot base the separation between the two taxa in question based on age difference. Thus Triceratium dobreeanum var. novazealandica is recognised as the species E. novazealandica , although future studies may demonstrate that both taxa are synonymous.

Figures

FIGURES 69–75. Scanning electron micrographs of Entogoniopsis novazealandica from Oamaru, New Zealand. Fig. 69: Oblique external view, showing the depressed valve face centre. Fig. 70: Detail of a hemispherical pseudocellus. Fig. 71: Oblique internal view of the specimen in Fig. 69. Note the absence of rimoportulae within the central depression. Arrow indicates a transverse costa next to the proximal side of a polar elevation. Fig. 72: Oblique external view of a specimen with a circumferential raised sector adjacent to the central depression. Fig. 73: Girdle view of a specimen with highly elevated polar pseudocelli. Note the offset of the polar elevations from the valve margin. Fig. 74: Oblique view of a specimen with attached valvocopula. Note clasping devices indicated by arrows. Fig. 75: Detail of the valvocopula attachment, with two clasping devices embracing internal costae visible. Arrow indicates the fossa, attached to the inwardly expanded hyaline margin of the mantle.

FIGURES 76–81. Light micrographs showing the range of morphological variation in Entogoniopsis novazealandica. Fig. 76: BM63524, Oamaru, New Zealand. Fig. 77: BM71533, Oamaru, New Zealand, lectotype; Fig. 78: BM46607, Oamaru, New Zealand. Fig. 79: BM coll. Adams G116, Jackson’s Paddock, Oamaru, New Zealand. Fig. 80: BM coll. Adams G659, labelled ‘(J.G.) Oamaru, New Zealand’. Fig. 81: BM46575, Oamaru, New Zealand.

FIGURES 82–86. Triceratium dobreeanum Norman ex Greville versus Triceratium dobreeanum var. novazealandica Grove & Sturt. Figs 82–83: Line drawings of Triceratium dobreeanum Norman ex Greville, reproduced from Greville (1865a: pl. II, Figs 23–24). Fig. 84: Light micrograph of T. dobreeanum holotype, BM3340, dredging off Sydney, Australia. Figs 85–86: Line drawings of Triceratium dobreeanum var. novazealandica, reproduced from Grove & Sturt (1886: pl. XIX, Figs 17–18); note the lack of linking spines at the summits of the polar elevations. Reproductions are not to scale.