Cephaloziellaceae Douin
Cephaloziellaceae Douin, Bull. Soc. Bot. France 29: 1, 5, 13. 1920.
Type: Cephaloziella (Spruce) Schiffn.
Plants typically strongly anisophyllous, exceptionally (Amphicephalozia) wiry, tending to be long and stringy, usually creeping (except Allisoniella), green but becoming brown, red-brown, fuscous or vinaceous in exposed sites, small to minute, to 350 µm wide, exceptionally to 500 µm wide. Branching often sparing and irregular, remote, the branches typically all or mostly of ventral-intercalary type; lateral-intercalary branches in some taxa; Frullania -type and/or Acromastigum -type branches present in a few species; stoloniform geotropic axes sometimes present. Stems usually wiry and firm, with cortical cells similar in size and form to medullary cells, or sometimes smaller, thick-walled and in 1–2 layers, a hyaloderm never present; medullary cell walls thin to firm. Rhizoids usually freely developed, never in dense fascicles, scattered (in Allisoniella mostly on flagelliform axes). Leaves usually small (except Allisoniella), usually transverse and vertically oriented (in ours), in some weakly to clearly succubous (incubous in Cephalojonesia), inserted dorsally to stem midline (except Cylindrocolea and Cephaloziopsis); leaves distant to contiguous, rarely imbricate, the stem usually extensively exposed, nearly always deeply bifid, unlobed (in some Kymatocalyx spp.) or retuse (Cylindrocolea), the lobes (when present) mostly narrowly acute, often divergent (when leaves flattened), the leaf margins entire or dentate. Cells usually very small, mostly only 7–15 µm wide in leaf middle, short-oblong and under 1.5:1, the walls thin to more often weakly to strongly, evenly thickened, without trigones; surface smooth or with low to coarse papillae. Oil-bodies small, usually 2–12 per cell, finely granular to subhomogeneous. Underleaves usually unlobed and range from small and lanceolate or ovate-lanceolate, to only 1–6-celled and vestigial, or reduced to ephemeral slime papillae visible only near shoot tips, exceptionally to 0.45 the area of leaves (often subequal to leaves in Amphicephalozia). Asexual reproduction by 2-celled gemmae produced in branched chains from uppermost leaf lobes on modified or unmodified leafy shoots.
Dioecious, autoecious or paroecious. Androecia nearly always on leafy axes or, at times, on abbreviated, leafless, ventral-intercalary branches, the androecia becoming intercalary, spicate, at times diffusely so; bracts bilobed like leaves (rarely obscurely so), pouched at base; antheridia nearly always 1 per bract, the stalk short, usually uniseriate. Gynoecia on leading leafy axes, occasionally on short ventral-intercalary branches lacking normal leaves; perigynium completely absent; bracts larger than and clearly differentiated from leaves, bilobed, often toothed even when leaves are entire; bracteole somewhat smaller than to subequal or equal to bracts (in Cephaloziopsis) reduced or vestigial, usually connate with one or both bracts. Perianth emergent to long-exserted, deeply 3–5-plicate, weakly to at most moderately narrowed to the usually wide, truncate, crenulate to ciliolate mouth, the cells at mouth usually thick- or thin-walled and strongly elongated.
Seta with 4 large outer + 4 much smaller inner rows or, occasionally, 8 large outer + 4–14 much smaller internal cells. Capsule ellipsoidal, the wall bistratose, or (Allisoniella) 3–4- layered; outer layer of cells with one-phase development, usually with discrete nodular thickenings on almost all longitudinal and many transverse walls; innermost layer of cells similar in size and shape, with weaker nodular thickenings sometimes extended as tangential spurs but rarely extending across the tangential wall.
Spores finely papillose to verruculose, very small, 6–13 µm in diam., subequal to elaters in diam., rarely 1.5–2× as large. Elaters rather stiff, at most feebly tortuous, little tapered toward the ends, bispiral.
The Cephaloziellaceae consist of eight genera, mostly very poorly understood. Allisoniella E.A.Hodgs. has five species, all south temperate. Amphicephalozia R.M.Schust. has two species, one, A. amplexicaulis R.M.Schust., from southern Chile, the other is A. geisslerae Pócs & Váňa from Madagascar (Pócs and Váňa, 2001). Cephalojonesia Grolle & Vanden Berghen is monotypic and occurs in Central Africa and Mexico (Burghardt et al., 2006). Cephalomitrion R.M.Schust. is monotypic and occurs in Australasia. Cephaloziella (Spruce) Schiffn. is worldwide. Cephaloziopsis (Spruce) Schiffn. has two species in the Neotropics and one in eastern Asia. Cylindrocolea R.M.Schust. has ca. 12 species, among them C. atroviridis (Sim.) Váňa of South Africa, C. novae-caledoniae (Grolle) R.M.Schust. of New Caledonia and C. tagawae (N.Kitag.) R.M.Schust., also of New Caledonia. Kymatocalyx Herzog (=Stenorrhipis Herzog) has four species and is pantropical. One, K. africanus Váňa & Wigginton, occurs in Africa (Tanzania [1600–2350 m] and Malawi [1200–2220 m]), one on the East African Islands (Madagascar, Mauritius, Réunion and Comoro Archipelago), one Neotropical and the last occurs in Malaysia, Sarawak, Sumatra and several stations in the Neotropics (see also comments in Schuster, 2002a).
Except for Allisoniella the species are so small that manipulation and study of material are very difficult and casual identification of material is almost prohibitively difficult. Vegetative differences often are not wholly reliable to distinguish between the genera, and, for generic determination, mature sporophytes should be carefully searched for, notably for seta cross sections. For species determination it is necessary to carefully dissect out whole plants in order to determine the sexuality.
The family includes three genera that are relatively primitive in having a more massive seta of the 8+4 or 8+4–12 type. These are Allisoniella and Cephalomitrion of our area and Amphicephalozia. The remaining genera all have a reduced, 4+4-type seta, which is very unusual in hepatics. For example, this seta type is also found in the unrelated Neotropical familyPhycolepidoziaceae R.M.Schust. of the Lepidoziineae.
