A taxonomic review of the Amazonian rheophyte Schusterolejeunea Grolle (Lejeuneaceae: Cololejeuneinae), with two new combinations Author Sierra, Adriel M. Instituto Nacional de Pesquisas da Amazônia, Departamento de Biodiversidade, Avenida André Araújo, 2936, Aleixo, CEP 69060 - 001, Manaus, AM (Brazil) and Département de Biologie, Université Laval, Québec (QC), G 1 V 0 A 6 (Canada) and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec (QC), G 1 V 0 A (Canada) adsierra 26 @ gmail. com (corresponding author) adsierra26@gmail.com Author Zartman, Charles E. Instituto Nacional de Pesquisas da Amazônia, Departamento de Biodiversidade, Avenida André Araújo, 2936, Aleixo, CEP 69060 - 001, Manaus, AM (Brazil) text Cryptogamie, Bryologie 2023 2023-04-12 20 4 107 122 http://dx.doi.org/10.11646/zootaxa.4878.3.2 journal article 250381 10.5252/cryptogamie-bryologie2023v44a4 23c643b8-8759-4bec-8e12-b8ac658108d9 1776-0992 7841602 Schusterolejeunea saxorum (Spruce) A.M.Sierra & C.E.Zartman, stat. nov., comb. nov. ( Fig. 5 ) Lejeunea inundata var. saxorum Spruce, Transactions and Proceedings of the Botanical Society of Edinburgh 15: 278 ( Spruce 1884 ) . LECTOTYPE . — Brazil . Est. Amazonas , San Carlos , in saxis fl. Negro inundatis, leg. Spruce L331/c (lecto-, designated here, MANCH !). SPECIMENS EXAMINED. — Brazil . Amazonas, São Gabriel da Cachoeira, Rio Marié, Marauna, 0°40’00”S , 66°45’00”W , 5.VII.1979 , Schuster R . M . 79-13-381 ( INPA !); Rio Uaupés, próximo a comunidade de São Pedro, 0°06’43.9”N , 67°39’19.1”W , 19.XII.2017 , Sierra A . M . 4760 ( INPA !, PMA !); Rio Uaupés, sitio São Paulo , 0°02’50.3”N , 68°29’05.7”W , epífita sobre ramas ao margem do rio, 21.XII.2017 , Sierra A . M . 5057 ( INPA !, PMA !), 5062 ( INPA !, SP !, PMA !); São Gabriel da Cachoeira, 0°40’00”N , 66°40’00”W , sobre galhos submersas na água, 5.VII.1979 , Yano O . 1734 ( INPA !, SP ); Rio Negro, igarapé Foibara, 0°16’18”S , 66°35’00”W , sobre pedras na cachoeira, 22.VII.1979 , Yano O . 2150 ( INPA !, SP ); Amazonas, Novo Airão, Parque Nacional Jaú, Carabinani river, 2°02’38”S , 61°33’28”W , X.2007 , Zartman C . E . 7542 ( INPA !); Roraima , Caracaraí, Parque Nacional Serra da Mocidade, Rio branco, 1°23’26.2”N , 61°40’19.2”W , 4.III.2017 , Zartman C . E . 9790 , 9888 , 9889 , 9892 , 9787 ( INPA !, PMA !), 9890 , 9794 ( INPA !, SP !), 9891 ( INPA !, SP !, PMA !), 9832 ( INPA !). See Appendix 1. DISTRIBUTION. — Schusterolejeunea saxorum (Spruce) A.M.Sierra & C.E.Zartman , stat. nov., comb. nov. is distributed in Amazonas and Roraima states. It is restricted to northern Amazonian tributaries of the Rio Negro: Rio Uaupés, Rio Jaú, Rio Marie ( Amazonas state ), and Rio Branco ( Roraima state ) ( Appendix 1 ). HABITAT. — This species is restricted to larger tributaries of the Rio Negro where it grows attached to rocks, branches, and tree trunks subject to seasonally flooding in igapó forests. FIG. 5. — Schusterolejeunea saxorum (Spruce) A.M.Sierra & C.E.Zartman , stat. nov., comb. nov. : A -C , gametophyte in ventral view, showing androecia and gynoecia branches; D , lobule close-up; E , F , single leaf detail,showing lobule shape variation; G , underleaf at apices; H , underleaf in mid portion of branches; I , leaf insertion showing basal leaf cells; J , mid leaf cells; K , rhizoids buds on basal portion of branches. Micrography from Zartman C.E. 9890 . Scale bars: A, 400 μm; B, C, E, F, 200 μm; D, 100 μm; G-J, 50 μm; K, 40 μm. DESCRIPTION Habit Plants small to medium in size, shoots up to 2 cm long and 0.2-1.5 mm wide, dark yellow to greenish-yellow when fresh, light brown when dry, pendent from leafless stoloniferous branches, shoots attenuate to the apices. Shoots highly branched, with numerous gametangia, usually with fertile innovations. Branches Lejeunea - type . Stems Primary stems 60-75 µm in diameter, in cross-section with 6-7 cortical and three medullary cells, cortical cells 22 µm in diameter, medullary cells 18 µm in diameter; thick-walled cells, epidermis slightly enlarged, hyalodermis lacking; ventral merophytes two cells wide. Leaves Distant, obliquely spreading to slightly erect, insertions short composed of two ventral and 3-4 dorsal cells, lobes (200) 600- 790 (870) µm long, (150) 370-455 µm wide, oblong, 2-3 as long as wide, apices widely rounded to truncate, plane, margins entire. Ventral margins slightly arched. Cells with numerous chloroplasts, oil bodies finely granular, 2-4 per cell; leaf lobe cells rectangular, subquadrate to irregularly polygonal, irregular in shape and size, thin walls, trigones small, intermediate thickenings scarce, cuticles smooth. Apical marginal leaf cells (sub)quadrate (15-25 ×14-25µ m), dorsal marginal cells rectangular to sigmoid-quadrate (13-29 ×9-15 µm), ventral marginal cells irregularly hexagonal (21-35×18-25µm), mid laminal cells hexagonal (18-30 ×15-20µm), with scarce intermediate thickenings, basal cells long rectangular to hexagonal (26-53 ×14-27 µ m), with scarce intermediate thickenings. Stylus unicellular. Lobules Large, well developed, forming a flat fold against the leaf lobe, rectangular to oblong (150) 400-560 µm long, (90) 260-340µm wide, covering 1/3-2/3 of leaf lobes, free margin plane, slightly inflated along the keel, slightly crenate by bulging cells, apices rounded-truncate. Teeth inconspicuous, formed by two cells with a marginal hyaline papillae terminal at the lobule apex. Underleaves Small and narrower than the stem, composed of 14-27 cells, (115) 275-450 ×(62) 95-125 µ m, 3× longer than wide, narrowly bifid with erect lanceolate lobes 8-11 cells long, and 3-5 at lobe base, ending in a 3-5 uniseriate cell, sinus deeply V-shape, rarely asymmetrical with one lobe reduced, forming a triangular fold of nine cells; underleaves usually absent along the basal portion of the stem. Rhizoids hyaline, up to 13 µm wide, and thick walls 4 µm wide. Autoicous Androecia usually on short lateral branches originating at the base of vegetative leaves, or on long terminal branches.Short spikes 590-640×465-520 µ m with 4-5 imbricate pairs of perigonial bracts, 320-360×170-195µ m, bracts emarginated at the apex. Gynoecia on short lateral branches originating at the base of vegetative leaves, in a monochasial row with 1-3 innovations. Female bracts short 330-400 × 295-330 µm, obovate, bilobed, margins entire, with emarginated or obtuse apices. Bracteoles like the underleaves.Perianths obovate 630×460µm, inflated with indistinct keels, at the apex with five indistinct low keels, at the apex slightly swollen forming short auricles, beak short 2-celled. COMMENTS It is readily recognized by its large rectangular to oblong lobules covering greater than half of the leaf lobe length, and its obovate perianth with indistinct keels. Lobule size varies within and between samples. Along a single shoot, the lobule may only cover 1/3 of the leaf surface in some instances and up to 2/3 of the leaf surface in other cases. However, lobules are always rectangular to oblong in S. saxorum (Spruce) A.M.Sierra & C.E.Zartman , stat. nov., comb. nov. , contrary to S. inundata var. fontinaloides (Spruce) A.M.Sierra & C.E.Zartman , comb. nov. in which its lobules are triangularly shaped covering less than 1/4 of the leaf surface.