Gleichenia ×punctulata Colenso

Morphologically intermediate between Gleichenia dicarpa and G. microphylla, combining character states found in the putative parents and/or with intermediate character states: e.g., plants with ± complanate ultimate segments that are glaucous on their abaxial surface, or plants with pouched ultimate segments but indumentum on the costae dominated by stellate scales with stiffly patent branches. The name G. ×punctulata applies to this hybrid combination.

The putative hybrids are found in the same habitats as G. dicarpa and G. microphylla, and usually grow with one or both of the parental species.

Morphological intermediates between Gleichenia dicarpa and G. microphylla are common. These are potentially hybrids and, while substantiating evidence is lacking (e.g., from spore morphology or genetics), that is how they are treated here. Their spores appear to be normally formed. While abnormally-formed spores provide strong evidence of hybridity in ferns, spores that appear normal do not rule out the plants being hybrids.

Most putative hybrids with Gleichenia microphylla involve the G. dicarpa morphological variant lacking both percurrent scales on the abaxial surface of the α costae and scales on the abaxial surface of the ultimate segments (group B; see Notes under G. dicarpa). But plants of G. dicarpa with percurrent scales on the abaxial surface of the α costae and scales on the abaxial surface of the ultimate segments from the northern North Island (group D; see Notes under G. dicarpa) also putatively hybridise with G. microphylla (e.g., Kawerua, A.E. Wright s.n., 13 May 1974, AK 223063; Opua, L.R. Perrie 4814, WELT P022337), although these are not included in the Gleichenia key.

Perrie & Brownsey (2015) noted that most of the syntype material of Gleichenia punctulata appears to be the hybrid between G. dicarpa and G. microphylla. The single exception is the piece at lower-left of WELT P003355/B, which belongs to group D of G. dicarpa (see Notes under G. dicarpa). Furthermore, Colenso’s protologue relates to both taxa (Perrie & Brownsey 2015). The lectotype was therefore selected to attach Colenso’s name to the bulk of the syntype material.

It is not clear which group of Gleichenia dicarpa is involved in the hybrid combination represented by the lectotype. While it was evidently collected with a specimen of group D, the lectotype lacks both percurrent scales on the abaxial surface of the α costae and scales on the abaxial surface of the ultimate segments, consistent with group B rather than group D. However, it is uncertain how these characters are expressed in hybrids of group D with G. microphylla, although at least some such putative hybrids have scales on the abaxial surface of the ultimate segments (see above).

Given the taxonomy adopted here, the binomial Gleichenia ×punctulata can be used for hybrids between G. dicarpa and G. microphylla. We note, however, that if segregates are formally recognised within what we here treat as G. dicarpa, the name G. ×punctulata may be difficult to apply. This is because of the uncertain parentage of the lectotype, discussed above.