Spruceanthus theobromae (Spruce) Gradst.

  • Authority

    Gradstein, S. Robbert. 1994. Lejeuneaceae: Ptychantheae, Brachiolejeuneae. Fl. Neotrop. Monogr. 62: 216. (Published by NYBG Press)

  • Family

    Lejeuneaceae

  • Scientific Name

    Spruceanthus theobromae (Spruce) Gradst.

  • Type

    Type. Ecuador. Los Rios: "Río Ventana propre Guayaquil, in Theobromae cortice" Spruce s.n. (G, MANCH 17343, 17344, W).

  • Synonyms

    Lejeunea theobromae Spruce, Ptychanthus theobromae (Spruce) Schiffn.

  • Description

    Species Description - Autoicous or paroicous, usually fertile. Plants robust, 3-3.5 mm wide, brown green when dry, loosely ascending to pendent (?) from bark. Branching Lejeunea-type, fertile plants becoming dichotomous by forked innovations, recurved flagelliform branchlets present on lower portions of stem. Stems robust, in cross section ca. 12-13 cells across, composed of ca. 35 epidermal cells surrounding numerous (over 100) medullary cells, outer medullary cells differentiated into a 1-2 layered subepidermis, epidermal and subepidermal cells smaller and more strongly thickened than inner medullary cells, wall of epidermis and subepidermis brownish pigmented, inner walls colorless; ventral merophyte ca. 16 cells wide. Leaves widely spreading when dry, contiguous to subimbricate, dorsal lobe ± oblong, 1.8-2.2 × 1.2-1.4 mm, apex rounded to apiculate, plane, margins entire, dorsal margin plane, ventral margin plane or slightly upcurved, forming a straight line with the keel; leaf cells distinctly elongate, in mid-leaf 35-40 × 15-20 µm trigones very small, irregularly radiate, tending to become coalesced, intermediate thickenings inconspicuous, 0-several per wall, the cell walls mostly thin, towards leaf margin conspicuously thickened; oil bodies not observed (homogeneous, Massula-type in Asiatic species); ocelli lacking. Lobules very small, all reduced to a small fold, apical tooth one-celled; hyaline papilla not observed. Underleaves rather small, distant, transversally ovate to suborbicular, 2-2.5 × stem width, ca. 0.6 × 0.5 mm, apex rounded, margins plane, the basal portions somewhat wrapped around the stem and concave in the comers, the bases and the insertion line straight. Androecia on short lateral branches or on main stem below the gynoecium, bracts smaller than leaves, in 3-7 series, lobule large, inflated, hypostatic, underleaves present throughout; antheridia not observed. Gynoecia with 1-2 lejeuneoid subfloral innovations, usually one pair of innovations below and repeatedly fertile single innovations above, the innovations often very short with perianths arranged in a series, bracts in one series, smaller than leaves, up to 1.5 mm long, lobe broadly lanceolate, acute, margins entire or with a few blunt teeth, lobule up to 1/2-2/3× lobe length, with 1-2 teeth near apex, keel short 0.1-0.2× lobe length, without wing, inner bract slightly different from outer bract, more flattened, narrower and with shorter keel; bracteole squarrose-canaliculate, narrow oblong, ca. 1.2 mm long, margins irregularly erose-dentate above, apex short bifid. Perianths long exserted, with 5-8 keels above: 2 lateral keels, 1-2 weak dorsal keels and 3-4 ventral keels (3 of them inserted on swollen main keel). Sporophyte (immature; seta non-articulate in Asiatic species): spores isodiametrical, with rosettes; elaters 72(?) per capsule, each with one spiral. Vegetative reproduction not observed.

  • Discussion

    Conservation. Spruceanthus theobromae has only been collected in the mid 19th century and in 1947. Since the 1960s most of the region where it occurs has been deforested, but the forest in the area of the Hacienda Clementina, where Harling collected the species in 1947, may still be intact (Prof. Gunnar Harling, pers. comm., Feb 1991). It is unknown whether S. theobromae continues to exists in the area; the species has been classified as "endangered" by Gradstein (1992c) and has been included in the IUCN World Red List. Its conservation is of considerable importance as the species is the only representative of Spruceanthus in the New World.

    Spruceanthus theobromae is a very distinct species, easily recognized by relatively large size (3-3.5 mm wide), its dichotomous habit, and its numerous, 5-8-plicate perianths which are often arranged in a series. By its gynoecia S. theobromae somewhat resembles Archilejeunea subgen. Dibrachiella (A. auberiana, A. parviflora), but differs by it much larger size and pendent (?) growth, robust stems with a clearly differentiated epidermis and subepidermis, flagelliform branches at the stem bases, elongated leaf cells, and by the pluriplicate perianths. All of these are diagnostic characters of the genus Spruceanthus, except for the elongated leaf cells which are a unique feature of S. theobromae. All other species of Spruceanthus have isodiametric leaf cells.

    Spruceanthus and Archilejeunea also differ by the occurence of homogeneneous oil bodies in the former and segmented oil bodies in the latter (Thiers & Gradstein, 1989). In S. theobromae oil bodies have not yet been observed, however.

  • Distribution

    A rare species known only from coastal Ecuador where it has been collected three times in the Province Los Rios, between Quevedo and Guayaquil. The species has been found growing on bark of a tree along a rivulet in virgin semi-deciduous rain forest at the foot of the Andes, and on cocoa trees, ca. 150-300 m.

    Ecuador South America| Los Ríos Ecuador South America|