Pterocladia. capillacea in New Zealand.
The New Zealand specimens examined can be divided without difficulty into two groups known commercially as P. lucida and P. capillacea.
The P. capillacea group is distinguished by small size (maximum about 30 cm. × 12 cm.), the cross section of the axis being oval in all parts except where it is occasionally almost circular, with the rhizines in young parts confined to the medullary region in the middle line (often forming a dumb-bell-shaped group in the whole T.S.), and, in the cystocarpic plant, by the usually single, strongly prominent, heavily rimmed carpostome.
To this group belong also P. nana, P. tenuis, and P. densa of Okamura, who gives no very convincing character separating these from P. capillacea. P. capillacea is stated to be (p. 63) “less broader, often more irregularly branched than P. tennis, and not constricted always to have pyramidal outline.” Setchell and Gardner (1937) compare their very similar G. (P.) okamuri with P. nana, but not with P. capillacea. Taylor's P. americana and P. bartlettii, which might otherwise be included in this group, are apparently distinct in that their tetrasporangial sori display clear V-shaped series.
In New Zealand material rather few plants are cystocarpic and this makes it difficult to eliminate the possibility that some might belong to species of Gelidium similar in form to P. capillacea. Among Okamura's illustrations, Pl. 16, Figs. 4 and 5 of G. pacificum, Pl. 19, Fig. 1 of G. amansii f. typica, Pl. 24, upper specimen of G; subfastigiatum, Pl. 28, Fig. 2 of G. clavatum, none of which represents a cystocarpic specimen, could all be fairly well matched among New Zealand P. capillacea. All New Zealand specimens sectioned, however, show in young parts rhizines more abundant in the medulla, with only an occasional one in the cortex, and therefore would be placed by Okamura in Pterocladia. It is perhaps worth noting that the rhizines are often very few; older parts of the axes are distinguished sometimes by the thickness of the cell walls, sometimes by an increase in number of rhizines, which in the main axes of the biggest plants may be evenly distributed throughout the whole cross section. The cells of the inner cortex are sometimes noticeably large and filled with floridean starch.
Gelidium corneum (Huds.) Lmx. has been recorded for New Zealand (see Laing, 1939, p. 141), and a number of specimens in the herbaria examined bear this name. None of the local specimens shows any good character to differentiate it from P. capillacea. Setchell (1931) published a photograph of what he considered to be the type specimen of Fucus corneus Huds., and concluded that G. corneum (Huds.) Lmx. in a strict sense was what Thuret later called G. sesquipedale.
P. capillacea. Figs. 1–3 from Waiotemarama. June, 1944, No. 44818. Fig. 1.—Twig with cystocarps showing 1, 2 and 5 ostioles. Fig. 2.—Profile of pinnule with two eystocarps. one with one ostiole, one with three Fig. 3.—L.S. of cystocarp with 4 ostioles opening from one loculus. Fig. 4.—From Opape, Buy of Plenty, February, 1941, No. 34054. Twig with tetrasporic Sori. P. [ unclear: ] ucidu.—Figs. 5 and 6 from Aohanga, April, 1943. Fig. 5, twig with tetrasporic sori. Fig. 6.—Twig with cystocarps; profile of one cystocarp. Fig. 7.—Camera lucida outlines showing positions of ostioles on cystocarps: a and [ unclear: ] from same plant, No. 28562, from O'Neill's Pt. Auck. W. coast, c from. Geraldton, W. Australia. Fig. 8.—Carpospore “chaplet” from 7c. Fig. 9 and 10.—T. S. pinnule, camera lucida outline and detail of median part. Fig-9 from No. 38505. Fig. 10 from No. 42986.
Specimens of P. capillacca.
No. 24632.—Waima Flat Reef. Tokomaru Bay. March, 1943. leg. Mrs. Tamati ♀.
No. 28481—Takapuna. October, 1940, leg. L. B. Moore. “Pool form” sterile.
No. 28540.—The Mount, Tauranga (west end), October, 1940. leg. L. B. Moore. Deep high-level pool sterile
No. 28672.—Ohariu Buy, Wellington, November, 1940. leg. R Mason, sterile.
No. 34088.—Te Kaha. Bay of Plenty, March, 1941, leg. L. B. Moore, ⊕
No. 42803.—Campbell's Beach, Pihama, Taranaki, January, 1944, leg. L. B. Moore, sterile.
No. 42928.—Oeo Beach, Taranaki, January, 1944, leg. L. B. Moore, ♀.
No. 4298.—Ohiro Bay, Wellington, March, 1940, leg. L. B. Moore, ⊕.
Feldmann and Hamel say (p. 127) “le G. sesquipedale ne contient de rhizines que dans la partie externe de la région médullaire; elles font totalement défaut au centre.” No Gelidium corneum-like plant with that axis structure has been seen here, and it seems safe to conclude that G. corneum in that restricted sense at least is absent.
A small Gelidium from Bay of Islands has recently been distributed from the Herbarium of Victor W. Lindauer as No. 137 Algae Nova-Zelandicae Exsiccatae under the name G. setchellii Lindauer sp. nov., accompanied by a description. This seems to be quite distinct from the Californian G. setchellii Gardner published in 1927. It is of the same order of size as the local P. capillacea, but even without cystocarps it has clear differences in habit, in the vertically elongated holdfast with numerous irregularly-produced stolons, and in the cross section showing rhizines scattered through the medulla and densely crowded in a conspicuous cortical region.
Within a wide range of frond form, the axis structure of local P. capillacea is fairly uniform, and the cystocarps, wherever they turn up, are typically Pterocladia. Cystocarps have not been noticed strictly basal on a pinnule, but on some specimens an occasional one is terminal. Tetrasporic sori are usually much longer than wide (Pl. 45, Fig. 4) with young and old sporangia mixed; even in the young apical part there is no clear V-shaped series; dehiscence is acropetal, but not at all regular.
Though the forms of P. capillacea, here as elsewhere, are legion, it has proved beyond the powers of the present writer to sort them into definable groups. In fact, it seems unlikely that any two people (or even the same person at two different times) would make the same dispositions if asked to separate the several hundred specimens in the Botany Division Herbarium into matching lots, without leaving any over. The range of form and size is illustrated (Pl. 46) and the figures show also the typical, rather wide-angle branching, often regular and strictly pinnate to tri-pinnate, with well-defined smooth primary and secondary axes, the former often devoid of branches basally, and with pinnae and pinnules constricted near the point of insertion. Our specimens seem to have much in common with those examined from England, France (Bairnitz, 9 Juillet, 1868, Bornet, ex Farlow Herbarium), Australia, Sandwich Is., Lord Howe Is., Norfolk Is., and Kermadec Is., and show no striking difference from a Japanese specimen ex Herb. Michitaro Higashi, Inatori, Izu, May, 1928, labelled P. capillacea, presumably the P. tenuis of Okamura. As Nos. 28540 and 42803* (Pl. 46) show, even parts of a single frond can exhibit contrasting shape, size, and habit of branching, demonstrating how unreliable these features are for systematic purposes. No more trustworthy basis for splitting has been found, and all the small Pterocladia of New Zealand with oval transverse section and predominantly medullary rhizines is regarded as belonging to one entity, presumably P. capillacea (Gmel.) Bornet et Thuret.
[Footnote] * Unless otherwise stated numbers are those assigned to specimens in the herbarium of the Botany Division, Plant Research Bureau, Wellington.