Tryonia Schuettp., J.Prado & A.T.Cochran, 2014

Cochran, Alyssa T., Prado, Jefferson & Schuettpelz, Eric, 2014, Tryonia, a new taenitidoid fern genus segregated from Jamesonia and Eriosorus (Pteridaceae), PhytoKeys 35, pp. 23-43 : 29-30

Tryonia Schuettp., J.Prado & A.T.Cochran gen. nov. Figs 4 , 6 -9

Diagnosis

Similar to some species of Jamesonia , but with stramineous rather than castaneous rachises.

Type.

Tryonia myriophylla (Sw.) Schuettp., J.Prado & A.T.Cochran, comb. nov., Gymnogramma myriophylla Sw., Kongl. Vetensk. Acad. Handl. 1817(1): 58. 1817.

Description.

Plants terrestrial, rupicolous, or saxicolous. Rhizomes creeping to erect at apex, compact, with appressed hairs or crispate bristles, sometimes rigid, ruddy brown, darker at the base. Fronds erect, 6-100 cm long; petioles terete or sulcate adaxially, brown at base and stramineous distally, from 1/8 as long to equal the length of the lamina, densely to sparsely pubescent, the hairs short and erect or long and crispate, hyaline or reddish brown at the cell junctions, glandular or non-glandular; laminae linear to elongate-triangular, 1 or 2-pinnate-pinnatissect to 1-3-pinnate-pinnatifid, 4.0-48 cm long, 1.0-14 cm wide, determinate; rachises straight, sometimes slightly flexuous, terete or sulcate adaxially, stramineous, pubescent, the hairs like those of the petioles; pinnae ascending to patent to the rachis, oblong to deltate, 0.5-10 cm long, 0.5-5 cm wide, membranaceous to herbaceous, densely to sparsely pubescent on both surfaces, the hairs glandular, hyaline or with the terminal cell light to dark red dish brown, 2-5-celled, or hairs non-glandular, hyaline or reddish brown at the cell junctions, 2-5(-7)-celled; ultimate segments entire and round or emarginate; veins free. Sporangia borne along the veins, short-stalked, stalks 1-2-celled, stomia with 2-4 indurated cells; spores trilete, tetrahedral-globose, with an equatorial flange, distal face coarsely tuberculate, proximal face with prominent ridges, brown, 40-60 µm ( Fig. 9 ).

Etymology.

The generic name honors Dr. Alice Faber Tryon, who made extraordinary contributions to fern systematics and published taxonomic revisions of both Jamesonia sensu stricto and Eriosorus (from which Tryonia is segregated herein).

Distribution.

Tryonia occurs primarily in southeastern Brazil. However, one species ( Tryonia myriophylla ) can also be found in Uruguay (Cerro Largo: Sierra Souza), near the Brazilian border. The genus is mostly restricted to the Atlantic Forest, along shaded streams, on damp shaded sandstone, or in more open places (but here shaded by shrubs); 600-2300 m.

Discussion.

Tryonia can be distinguished most readily from Jamesonia by its stramineous rachises, but its gross morphology is also reasonably distinct. Tryon (1970) referred to the leaves of Tryonia myriophylla as “generalized” (i.e., elongate-triangular and well developed). She drew a distinction between them and the “specialized” (i.e., either complex and scandent or compact and linear) leaves of Jamesonia sensu stricto and many other species at the time placed in Eriosorus , as well as between them and the “intermediate” (i.e., falling between the two extremes) leaves of other species she treated in Eriosorus . Although the Andean Jamesonia congesta also has “generalized” leaves, it is readily distinguished from Tryonia by its rachis color. The only species of Jamesonia with occasionally stramineous rachises ( Jamesonia flexuosa ) has “specialized” (complex and scandent) leaves. Spores of Tryonia ( Fig. 9 ) and Jamesonia are basically indistinguishable.

Tryonia comprises the following species.

Figures

Figure 4. Tryonia myriophylla (Sw.) Schuettp., J. Prado & A. T. Cochran, the type species of Tryonia. Smith 1795 (US), inset detail of (stramineous) rachis magnified 4 x.

Figure 6. Tryonia areniticola (Schwartsb. & Labiak) Schuettp., J. Prado & A. T. Cochran. Schwartsburd 487 (SP), inset detail of (stramineous) rachis magnified 4 x.

Figure 9. Spores of Tryonia. A. Tryonia myriophylla proximal view, Wacket s. n. (US) B Tryonia myriophylla distal view, Wacket s. n. (US) C Tryonia areniticola proximal view, Kummrow 2773 (US) D Tryonia areniticola distal view, Kummrow 2773 (US). All scale bars are 20 µm.