Castanoclobos
Castanoclobos J.J.Engel & Glenny, Novon 17: 424. 2007.
Type: Castanoclobos julaceus (Hatcherex J.J.Engel) J.J.Engel & Glenny (≡Leiomitra julacea Hatcherex J.J.Engel)
Plants spongy, distinctly julaceous, with all sides appearing as a mass of interwoven cilia, loosely creeping, chocolate-brown (the shoot tips light green), the shoots to 2 mm wide. Branching irregularly sympodial to pseudodichotomous, the leading axis soon losing its dominance, the main shoot and branches alike in vigor. Stem lacking paraphyllia, hidden on all sides by interwoven leaf cilia. Rhizoids occasional, in tight bundles, from stem at immediate base of underleaves, the tips often branched. Leaves widely spreading but with lobes arching toward shoot apex, rather closely imbricate, distinctly succubously (almost longitudinally) inserted, the lamina twisted: ventral sector of leaf oriented parallel with substrate, the dorsal sector of leaf antically assurgent and the dorsal margin seen on edge, the leaves obtrapezoidal to subreniform, 1250–1650 µm wide × 880–1130 µm long, asymmetrically 4–6-lobed, the ventral pair of lobes largest, the dorsal lobe smallest. Lobes caudate, not 3-fid, the ventral pair of lobes 4–5 cells wide at base (tier immediately above sinus base), then 2–3 tiers of laterally juxtaposed cells basal to the uniseriate row of 6–10 cells; cells of uniseriate row ± cylindrical, with dilated septa, 13–25 µm wide, 62–98 µm long, the cells toward base of uniseriate row rather thick-walled, the cells becoming progressively smaller and less thick-walled toward lobe apices, the surface of penultimate and terminal cells striolate-papillose, that of the remaining cells finely striolate; terminal cell of uniseriate row somewhat tapered, 10–12 µm wide, 68–90 µm long, slightly thick-walled in the tip; margins of lobes copiously armed with pairs of opposing cilia, the cilia of lobes and sinus bases repeatedly dichotomously branched, the branches of each dichotomy stiffly diverging, but the armature primarily directed adaxially and oriented at right angles to the leaf plane, the leaf thus appearing to have a stiffly ciliate adaxial leaf surface, the cilia ultimately forming a densely interwoven dendroid crown to the leaf; marginal cilia of lobe uniformly uniseriate throughout, the cells elongate, rather thick-walled, the surface of cells toward base of cilium striolate, the surface of cells toward and including terminal cell striolate-papillose; sinus bases plane and not reflexed. Disc slightly convex, asymmetric, 3–4 cells high at dorsal sinus, 5–6 cells high at ventral sinus (from base to sinuses); margins of disc with dichotomously branched cilia similar to those of lobes, the cilia often adaxially displaced and lying at right angles to the disc plane. Cells of disc thin-walled, strongly elongated, aligned in somewhat irregular tiers, in lamina middle 22–26 µm wide, 84–108 µm long; surface markedly long-striolate, with only a few papillae. Underleaves somewhat smaller than leaves, narrowly connate on both sides, cuneate, quadrifid, the marginal armature similar to leaves and likewise forming a mass of interwoven cilia; disc 3–4 cells high. Asexual reproduction lacking.
Dioecious. Androecia intercalary on main shoot, notably inconspicuous, the bracts in ca. 3 pairs, of similar size to leaves, transversely inserted at dorsal end, moderately ventricose in basal sector, the dorsal margin somewhat dilated and inflexed, the disc a little higher than leaves (6 cells high at dorsal sinus), the bracts otherwise as in leaves; antheridia large for bract size, 1 per bract, the stalk biseriate. Gynoecia isophyllous, terminal on main shoot, sporadically on long Frullania -type branches, subfloral innovations lacking; stem perigynium present, 2(3)-stratose, obscurely and bluntly trigonous, with 3 series of bracts and bracteoles inserted on it, the bracts and bracteoles with their laminae erect, clasping the perianth and closely adhering to its contours but with the lobes moderately spreading, each series ensheathing the perianth, the lateral margins mutually connivent but free from one another; bracts and bracteoles similar in size and form, deeply convex (dorsal view), those of first and second series subequal in size, those of innermost series similar to bracts and bracteoles of series immediately below (second series) except for the slightly smaller size, the less armed lobe bases and the greater number of simple cilia of the lamina margins, the bracts and bracteoles of innermost series symmetrically narrowly ovate, 3–4-lobed to 0.35–0.45, the lobes long-ciliiform, terminating in a uniseriate row of 7–11 elongated, thick-walled cells with slightly swollen septa, the lobe bases entire or with 1–2 pairs of opposing simple or branched cilia, the lamina distinctly inflated at base, the margins with simple (or somewhat less common) once-forked cilia, the 2 cilia of “fork” subequal. Perianth present and well developed, the transition from stem perigynium to perianth not evident in either external or internal aspect, the outer surface of the entire sporophyte protective device (stem perigynium + perianth) densely invested with short, simple or branched hairs (the inner face of the perianth with a few hairs distally, smooth in median and basal sectors), the perianth rather sharply trigonous distally (the third keel ventral), the intervening sulci deep, the perianth tapered toward mouth, the mouth not or at most feebly contracted, fringed with stiff cilia, the cilia comprised of 2–4 elongated (to 9:1) thick-walled cells with a distinctly papillose surface, the tip cell tapering to a rather sharp summit; perianth unistratose (or locally bistratose) in distal and median sectors. Shoot calyptra apparently lacking, the unfertilized archegonia at or near calyptra base (gynoecia seen only in a state soon after fertilization).
Sporophyte unknown.
A monotypic genus with only C. julaceus, endemic to New Zealand. Engel and Glenny (2007) removed the species from Leiomitra and established a new genus for it based upon presence of a well-developed perianth, trigonous and ciliate at the mouth, and brown pigmentation.
References: Engel (1999b); Engel and Glenny (2007).
