Castanoclobos julaceus
Leiomitra julacea Hatcher ex J.J.Engel, Novon 9: 26. f. 1. 1999.
Castanoclobos julaceus (Hatcher ex J.J.Engel) J.J.Engel & Glenny, Novon 17: 425. 2007.
Holotype: New Zealand, Stewart Is., Port Pegasus, Sawmiller’s Arm, 1949, Martin 621 (F); isotypes: (CHR, UWM).
Distribution and Ecology : Endemic to New Zealand. Known only from the type collection, two specimens from South Cape on Stewart Island, from the Cascade ultramafic moraine in southern Westland and on the nearby Teer Plateau. At the Cascade, the species occurs at ca. 135 m in an area of ultramafic rocks and outcrops with rather open vegetation consisting of mainly of Gleichenia, Lycopodium, Juncus, the lichen Cladonia and scattered Leptospermum scoparium. The species forms thick, nearly pure mats on well-drained soil of slopes and vertical banks of drainage channels. On the Teer Plateau, it was found under short Leptospermum scoparium, Halocarpus biformis and Lepidothamnus intermedius forest at 340 m, with Acromastigum anisostomum and Geocalyx caledonicus. One of the South Cape sites is at 200 m, in wind-swept prostrate Leptospermum scoparium shrubland up to 80 cm high, with Gahnia procera and Dracophyllum longifolium, on peat, with Acromastigum anisostomum, Adelanthus occlusus, Anastrophyllum schismoides and Campylopus clavatus. A second, nearby site had Dracophyllum longifolium, Lepidothamnus intermedius, Leptospermum scoparium and Olearia colensoi scrub 1.5–2.5 m high, and the plants were on peat with Adelanthus occlusus, Lepidozia ulothrix, Leptoscyphus australis and Marsupidium surculosum. At the type locality, the vegetation included Nothofagus solandri, and perhaps Lepidothamnus intermedius. Accompanying species were Cladia aggregata, Cladina confusa, Jamesoniella colorata, Plagiochila baileyana, Radula dentifolia and Telaranea herzogii. Hatcher (1958) mentions that the type was “epiphytic; on forest trees” but the presence in the type collection of leaf litter and Plagiochila baileyana makes this doubtful.
The generic description serves to characterize the single species.
Comments : The species, known for many years only sterile, initially was described as a Trichocolea by Hatcher (1958) and transferred to Leiomitra by Engel (1999b). Engel and Glenny (2007) demonstrated that the gynoecium of Castanoclobos julaceus is quite different from that of Leiomitra. In Leiomitra the bracts and bracteole of the innermost series are well developed and either free and then a perianth entirely lacking, or fused to form a low, vestigial perianth (e.g., L. lanata, Fig. 23: 2). Castanoclobos, on the other hand, has a well-developed perianth that is rather sharply trigonous distally (Fig. 22A: 5, cross section) and has a ciliate mouth (Fig. 22A: 6). The perianth is subtended by a stem perigynium with three cycles of bracts and bracteoles inserted on it (Fig. 22A: 1). In Castanoclobos the surface of the entire sporophyte protective device (stem perigynium + perianth) is densely covered with short, simple or branched hairs (Fig. 22A: 1, 7–10) vs. a smooth coelocaule surface in Leiomitra.
Engel and Glenny (2007) retained Castanoclobos in the Trichocoleaceae because of the distinct presence of a trichocoleoid gametophyte architecture, especially the form of the leaf lobes with branched cilia, and the complete lack of ventral-intercalary branching; both of these characters are absent from the Pseudolepicoleaceae, where some might argue that it may belong. Molecular studies perhaps may prove useful in establishing the systematic affinities of Castanoclobos.
The leaves of this species are remarkable for their development of a densely interwoven “basket-work” of cilia (Fig. 22: 4–6), which causes the axis and branches to appear spongy and julaceous (Fig. 22: 2); the cilia are repeatedly dichotomously branched and widely divergent, the ultimate divisions of each leaf forming a densely interwoven dendroid “crown.” Branching is irregularly sympodial to pseudodichotomous, as in Leiomitra lanata (see Figs. 22: 2; 23: 1), but the form of the leaves is very different in the two species. In L. lanata leaf lobes are equally 3-fid, consisting of an adaxially divergent segment and a pair of abaxially divergent segments, each segment usually 1(2) times again 3-fid, ending in a pair of ± equally divergent, uniseriate cilia. In C. julaceus, on the other hand, leaf lobes are not 3-fid, but rather simply caudate, with margins armed with pairs of opposing cilia (Fig. 22: 1). The cilia are repeatedly dichotomously branched and form a densely interwoven dendroid crown (Fig. 22: 1, 4, 5).
The species is readily distinguished in the field by the julaceous, wiry aspect of the plants coupled with the brownish color.
