Equisetum laterale Philipps emend. Gould, 1968

Pole, Mike, 2019, Middle-Late Jurassic plant assemblages of the Catlins coast, New Zealand, Palaeontologia Electronica (a 51) 23 (3), pp. 1-48 : 14

Equisetum laterale Philipps emend. Gould, 1968

Figure 8

1829 Equisetum laterale Philipps , figs. 2, 3; pl. 1, figs. 1–22; pl. 2, figs. 1–18.

1917 Equisetites nicoli Arber , p. 26, plate 3, fig. 2.

1934 Equisetites nicoli Arber ; Edwards, p. 90, pl. 4, fig. 3.

1968 Equisetum laterale Gould , p. 157, figs. 2, 3; pl.

1, figs. 1-22; pl. 2, figs. 1–18.

1989 Equisetum laterale Philipps emend. Gould, Gee , p. 157, pl. 1, figs. 3, 4, 5, 6.

Material. Little Beach-04: LX1063–1067, Otara-20: Noted in the field, Otara-32: LX0657, Otara-33: LX0710–0712, Otara-34: LX0714–0716, 1496, 1497, Otara-35: LX2684, Owaka: LX0993–0995, 0999, 1001, 1003–1005, 1007–1010, 1166.

Description. Stems mostly 2.5–17 mm diameter (flattened), some specimens (LX1496) appear to be over 20 mm, c. 14 leaves in a whorl, 6.0 mm long, 1.5 mm wide ( Figure 8.2 ). Nodal diaphragm c. 10 mm in diameter, with 29 ‘spokes’ ( Figure 8.1 ).

Remarks. Two species of Equisetum have been described from the Southland Jurassic (as Equisetites ), both of them falling within the Mesozoic group that has wheel-like nodal diaphragms (Harris, 1961). Arber (1917) described E. nicoli from the inland location of Mokoia. He compared it with the European E. laterale (as E. lateralis ), saying “They may even be identical, though at present I should be inclined to regard them as specifically distinct.” Arber (1917, p. 26) never clearly stated what the differences were with E. laterale , but said “There are, however, several points of agreement with E. laterale . The…nodal diaphrams…are similar…, though probably not identical. There are fewer “spokes in the wheel” of the New Zealand fossil.” Arber did not describe the number of spokes, but his figures show about 18–19.

Subsequently, Edwards (1934) described Equisetum hollowayi from a “roadside cutting about ½ mile inland from Curio Bay.” It differed from E. nicoli in being “smaller in all of its parts” and “fewer and very much shorter leaves in the whorl and fewer “spokes” in the nodal diaphragm. The stems were less than 10 mm in diameter and diaphragms 2–4 mm in diameter with 9–14 spokes. Gould (1968) regarded E nicoli as “closely comparable” to E. laterale , a species that Gee (1989, p. 158) noted is “known from Mesozoic sediments all around the world, particularly in the Australasian area.”

The type horizon of Equisetum hollowayi has not been relocated, but Equisetum is present at other localities. A single diaphragm from the Otara coast has 29 “spokes” in the nodal diaphram which is about 10 mm in diameter. This nodal diaphragm is thus much larger than E. hollowayi and with more than twice the number of nodal spokes. Equisetites nicoli has a comparable nodal diaphragm diameter, although the number of spokes is slightly less. The present fossil is comparable to E. laterale in this respect. Given Arber’s (1917) vague criteria for why E. nicoli was distinct from E. laterale , plus the widespread nature of the latter as currently understood, it seems pragmatic to regard E. nicoli and the new material as E. laterale .

Equisteum fossils from the Miocene of New Zealand (Pole and McLoughlin, 2017) have much broader stems, many more leaves, and no diaphragms.

Figures

FIGURE 8. Equisetum laterale. 1. Diaphragm, LX2684, Otara-35; 2. Leaf sheath, LX1008, Owaka; 3. Possible rhi- zome, LX1066, Little Bay-01. All scale bars equal 10 mm.