Coniopteris, A.T.Brongniart, 1849

Pole, Mike, 2019, Middle-Late Jurassic plant assemblages of the Catlins coast, New Zealand, Palaeontologia Electronica (a 51) 23 (3), pp. 1-48 : 10

Coniopteris and Sphenopteris

Remarks. Edwards (1934) maintained that “With the possible exception of Cladophlebis australis [ Coniopteris ] is the most abundant fossil in nearly all the New Zealand Jurassic localities…” However, the boundaries of the genus are vague, particularly with respect to Sphenopteris , from which Brongniart (1849) segregated Coniopteris . Some workers restrict the use of Coniopteris to fertile material and use Sphenopteris for sterile, whereas others have posed various morphological criteria for segregation. For example, Arber (1917) identified both sterile Coniopteris and Sphenopteris from the Catlins coast, although it is unclear what his distinguishing criteria were. He appears to have followed Seward (1904), quoting him that for Coniopteris hymenophylloides , “Venation and form of the frond [is] of the Sphenopteris type ”. Other workers have cited various distinguishing characters, Medwell (1954, p. 86) wrote: “ Coniopteris tends to have more bluntly rounded lobes than Sphenopteris , but the distinction is small.” Douglas (1969, p. 85) considered that “Fertile S. warragulensis and Coniopteris specimens are easy to distinguish. The sori on the tips of the Coniopteris pinnules are much smaller and very rarely aggregated, and average about five per pinnule— S. warragulensis has one?rarely two sori per pinnule or indentation.” Gee (1989, p. 170) regarded Sphenopteris as “a form genus established for pinnules which are constricted at the base, often attached by a short stalk, elliptical in outline, with a margin lobed or toothed, with lateral veins that diverge from the relatively straight or flexuous midvein at low angles singly or in groups.” She used Coniopteris for similar, but fertile material. To McLoughlin and Drinnan (1995, p. 265) Sphenopteris was a “bipinnate frond and dissected pinnules with sinuous veins” and McLoughlin et al. (2002) described fertile Sphenopteris .

In the present work sterile material is regarded as Sphenopteris and fertile as Coniopteris . This follows Gee’s (1989) concept of Sphenopteris as a typical form genus , but Coniopteris as a ‘real’ genus. In reality, the Catlins species are probably forms of the same taxon.

The present material is similar to Arber’s Sphenopteris otagoensis and probably also to his sterile Coniopteris hymenophylloides . The Australian Sphenopteris travisii (Stirling, 1900; Drinnan and Chambers, 1986; McLoughlin et al., 2002) is regarded as identical and has priority. In terms of lobe shape and dissection, Catlins Sphenopteris do not compare well with any of the Hope Bay (Gee, 1989; Rees and Cleal, 2004) species. For instance, the pinnules are not reduced to wings of lamina surrounding the midvein and lateral veins as in S. bagualensis and S. nordenskjoeldii , but the basiscopic margins do taper gradually until they meet the proximal pinnule as per S. anderssonii . However, the pinnule lobes of S. andersonii appear much more rounded and more subdued on the basiscopic margin.

A single Catlins fertile specimen is regarded as Coniopteris . It has slightly narrower pinnules and pinnule lobes than Sphenopteris otagoensis and has a prominent round sorus at the end of each lobe. The form of the pinnules and aspect of the sori agree with C. murrayana as figured by Harris (1961). Furthermore, Gee (1989) identified Arber’s (1917, text fig. 9) similar fertile Curio Bay Coniopteris hymenophylloides as C. murrayana and regarded it as “identical” with material from Hope Bay. Guy-Ohlsen (1979) also reported C. murrayana from Curio Bay, and it is regarded as a cosmopolitan species. Rees and Cleal (2004) dealt differently with the Hope Bay material. They identified a C. cf. murrayana and kept fertile specimens that had been placed into C. hymenophylloides by Halle (1913) and Gee (1989), as informal species of Coniopteris . Specimens identified as C. cf. murrayana by Rees and Cleal shows deeply dissected lobes and fewer lobes per pinnule (5 as compared with c. 7).

The Coniopteris murrayana specimen and Sphenopteris otagoensis documented here occur in the same bed and probably belong to be the same ‘natural’ taxon.