Heppia trinitatis, a Member of the Peltigeraceae

Abstract

trinitatis Vain. from Trinidad is reinterpreted as belonging to the Peltigeraceae and a member of the previously monotypic genus Hydrotheria. The appropriate new combination is made. Vainio (1923) described trinitatis, a sterile lichen collected by Thaxter in Trinidad on rocks in a stream. The lichen is characterized by bluish-gray, compact lobes with a canaliculate-concave underside and roundish isidia. An examination of the isotype material in the Farlow Herbarium revealed young stages of apothecia of the ontogenetic Peltigeraceae type (Henssen 1963a, p. 1333; 1963b, p. 101). Asci and spores were not seen but the paraphyses were typical, relatively thick, distinctly septate with partly pointed tips and short basal cells, very similar to those of Hydrothyria venosa (compare Fig. 2 and 3). trinitatis has Nostoc as symbiotic alga like Hydrothyria in contrast to species. Finally, the external and internal morphology of trinitatis thallus does not correspond to that of the other species but resembles most closely that of certain Collema species. For the present time, it seems to me best to place trinitatis into the hitherto monotypic genus Hydrothyria. Characters in common with Hydrothyria venosa are the development type of the ascocarp, the phycobiont, and the habitat. Hydrothyria venosa differs by a corticate thallus; in trinitatis no cortex develops. Hydrothyria trinitatis (Vain.) A. Henssen, comb. nov. (Fig. 1, 3, 4, 5A-D). trinitatis Vain., Proc. Amer. Acad. Arts & Sci. 58: 132. 1923. (= Heppia Trinitatis.) Type: Trinidad, St. Ann's Valley, Thaxter 36 (Holotype--Tim; isotype--FH). Thallus foliose, to 2.5 cm broad, leador bluish-gray. Lobes abundantly branched, to 20 mm long and (0.25-)0.4-0.7 mm broad, flat or somewhat convex above, canaliculate-concave below, attached to the substrate by tufts of whitish rhizinae. Lobes with marginal and laminal isidia, isidia at first roundish, later elongate and branched, typically produced along the thallus margin but laminal as well. Thallus in longitudinal section 200-300ku thick. Hyphae 2.5-4.5[k thick, aggregated in the center of the thallus and parallel to the longitudinal axis of the lobes, bending upwards to the outer part of thallus and then oriented at right angles to the thallus surface, the uppermost cells enlarged (Fig. 1). 1 This study was supported by a grant of the Deutsche Forschungsgemeinschaft. I thank the directors and curators of Farlow Herbarium of Harvard University and of the Musea of the Universities of Uppsala and Turku for the loan of material and Miss Ursula Schultz for preparing the drawings. 2 Botanisches Institut der Universitdit Marburg, Germany. This content downloaded from 207.46.13.189 on Thu, 16 Jun 2016 06:40:29 UTC All use subject to http://about.jstor.org/terms 1968] HENSSEN: HEPPIA TRINITATIS 269