taxonID	type	description	language	source
FF513D428D13FF9DFF4FFDCBFAE5A855.taxon	materials_examined	Type: — Georgia, Kvirike (distr. Kobuleti): western slope of ravine forest ca. 3.5 km ENE of the village centre, elev. 180 m, 41 ° 46 ‘ 42.8 “ N, 41 ° 51 ‘ 50.1 “ E (WGS- 84), 22. 7. 2023, Pavel Novák & Vojtěch Taraška (holotype CBFS 10624). Isotype: — BRNM 848227 Paratype: — Georgia, Atabe (distr. Dusheti): ca. 100 m SE of the settlement, elev. 1925 m, 42 ° 33 ‘ 56.6 “ N, 44 ° 58 ‘ 25.4 “ E, 14. 9. 2022, leg. V. Kalníková (BRNU, field no. 22 - 31). — Georgia, Atabe (distr. Dusheti): ca. 600 m WWS of the settlement, elev. 1725 m, 42 ° 33 ‘ 53.960 “ N, 44 ° 57 ‘ 55.400 “ E, 14. 9. 2022, leg. V. Kalníková (BRNU, field no. 22 - 33). — Georgia, Khizabavra (distr. Lagodekhi): a forest above the left bank of the Ninoskhevi brook, 2.7 km SW from Ninoskhevi waterfall, elev. 645 m, 41 ° 52 ‘ 50.0 “ N, 46 ° 14 ‘ 41.0 “ E, 3. 8. 2018, leg. P. Novák (CBFS). — Georgia, Apsho (distr. Dusheti): ca. 3.96 km WSW of the Mt. Ubistavi (2329 m) ca. 2.57 km NNE of the Khomi hotel, elev. 1110 m, 42 ° 23 ‘ 17.4 “ N, 44 ° 55 ‘ 12.3 “ E, 30. 9. 2022, leg. P. Lustyk (BRNU). — Georgia, Tkhiliana (distr. Dusheti): ca. 480 m SW of the junction Pshavis Aragvi river and Kevshuretis Aragvi river, ca. 3.98 NW of the Mt. Ubistavi (2329 m), elev. 1200 m, 42 ° 25 ‘ 23.4 “ N, 44 ° 56 ‘ 19.4 “ E, 30. 9. 2022, leg. P. Lustyk (BRNU). — Georgia, Uravi (distr. Ambrolauri): Alnus incana forest 7.2 km NNW from church in the village, elev. 1285 m, 42 ° 42 ‘ 36.5 “ N, 43 ° 16 ‘ 39.2 “ E, 15. 7. 2024, leg. P. Novák (TBI). — Armenia, Tavush Province, Ijevan: Fagus forest, valley 6.4 km SW from the city center, elev. 1310 m, 40 ° 51 ‘ 1.200 “ N, 45 ° 4 ‘ 41.200 “ E, 10. 5. 2025, leg. Novák, P. & Dřevojan, P. (BRNU). — Armenia, Lori Province, Haghpat: ravine ca 3.3 km SSE of the town centrum, elev. 1210 m, 41 ° 3 ‘ 58.589 “ N, 44 ° 43 ‘ 35.860 “ E, 16. 5. 2025, leg. P. Novák (BRNU). — Turkey, Karagöz: above road D 855 ca 1.6 km SW of the village centrum, elev. 980 m, 40 ° 39 ‘ 41,472 “ N, 37 ° 36 ‘ 10,536 “ E, 5. 9. 2025, leg. L. Ekrt & K. Vejvodová (CBFS, PRC). — Turkey, Ikizdere, Ilicaköy: valley of Cimil Deresi below Ilicaköy village ca 2.8 km ENE of the Ikizdere centrum, elev. 775 m, 40 ° 47 ‘ 14,718 “ N, 40 ° 35 ‘ 27,360 “ E, 7. 9. 2025, leg. leg. L. Ekrt & K. Vejvodová (CBFS). — Russia, Flora caucasica, Ordschonikidse, bewaldete Hügel östl. der Stadt, Buchenwald, Kalk, 800 – 1000 m, 11. 7. 1966, leg. F. K. Meyer et J. Meyer, as Polystichum braunii (Spennner) Fée (JE 7903, rev. S. Jessen, see Supplement 3). — Russia, Flora caucasica, Teberda, Dombai, Amanaus-Tal, 2000 – 2200 m, 9. 8. 1989, leg. F. K. Meyer et J. Meyer (JE 16472, rev. S. Jessen). — Russia, Flora caucasica, Teberda, Tal des Ullu-Murudshu, Schluchtwald, ca. 1400 m, 15. 8. 1957, leg. F. K. Meyer, H. Lippold, E. Köhler, as Polystichum braunii (Spennner) Fée (JE 632, rev. S. Jessen). — Russia, Flora caucasica, Kluchorpass, Klytschtal, 1800 m, 20. 7. 1964, leg. F. K. Meyer et J. Meyer, as Polystichum braunii (Spennner) Fée (JE 7375, rev. S. Jessen).	en	Ekrt, Libor, Jessen, Stefan, Novák, Pavel, Vejvodová, Kateřina, Kalníková, Veronika, Lustyk, Pavel, Fraser-Jenkins, Christopher R. (2025): Polystichum caucasicum sp. nov. (Dryopteridaceae), a new, surprisingly hexaploid fern species from the Caucasus. Phytotaxa 736 (3): 275-287, DOI: 10.11646/phytotaxa.736.3.4, URL: https://doi.org/10.11646/phytotaxa.736.3.4
FF513D428D13FF9DFF4FFDCBFAE5A855.taxon	diagnosis	Diagnosis: — Polystichum caucasicum is morphologically very similar to P. braunii (Spenn.) Fée (1852: 278) in having densely scaly lanceolate-ovate lamina and sharing same plant size, but the former has mean guard cells size 54 – 64 µm (vs. 44 – 50 µm, in the latter), with 1.5 - 2 mm long terminal awn, longer-pointed pinnae (vs. bluntly pointed in the latter), enlarged basal acroscopic pinnula, the pinnae slightly looser, usually with an elongated and narrowly pointed end (vs. with an abruptly and bluntly pointed end), pinna width (central part of the frond) in the terminal 1 / 3 is 1.1 – 1.4 cm (vs. 1.5 – 1.9 cm in the latter). Plants perennial, evergreen, coriaceous, 50 – 90 cm tall. Rhizomes ascending, single-headed or multi-headed in older plants with remnant bases of old petioles. Leaves in rosette-shaped tufts; petioles (8 –) 10 – 15 (– 20) cm long, ca. 3 – 8 mm diam., petiole scales of two types, the first ovate to ovate-lanceolate, 10 – 15 × 2 – 6 mm, transparent, papery, dull light brown, margins slightly toothet to fimbriate, apex acuminate; the second usually linear to narrowly-lanceolate, 6 – 10 × 0.5 mm, membranous, light brown, apex long-acuminate or caudate. Laminae lanceolate, 2 – pinnate, 35 – 70 cm, apex acuminate; rachises ca. 3 – 6 mm diam., brown; rachis scales of two types, the first scatteredly only on proximal part ovate-lanceolate or lanceolate, light brown, up to 0.8 mm long, long acuminate, entire margins with irregularly fimbriate, apex long-caudate; the second densely covered with bristle-like, up to 5 mm long, margins entire. Pinnae 25 – 35 pairs, usually alternate, separate from each other 15 – 30 cm apart, lanceolate, largest pairs (5 –) 7 – 9 (– 11) × 1.5 – 2.5 cm, usually in the center of lamina, basiscopic and acroscopic sides relatively symmetrical, apex acute; pinna petioles 1 – 2 mm long. Pinnulae in 10 – 17 pairs, alternate or opposite, unilaterally auriculate, acroscopically auriculate, largest pairs in central part of pinna 7 – 15 mm, basal acroscopic pinnules slightly enlarged 9 – 20 mm; pinule-margins with distinctive bristles (0.5 –) 1 – 2 mm, terminal awn strikingly long, 1.5 – 2 mm; abaxially with dense microscales, adaxially with scattered microscales; microscales fibrillose, whitish brown. Fertile pinnae in upper 1 / 2 or 1 / 3 part of the frond; sori borne on the lower parts of hte pinnae, 0.8 – 1.2 mm diam., (4 –) 8 – 10 (– 12) per pinnula; indusia present. Spores well-developed, (45 –) 50 – 57 (– 60) μm. Guard cells (47 –) 56 – 64 (– 73) µm. Mean genome size 2 C = 44.7 pg, hexaploid, 2 n = probably 246. Geographical distribution: — Polystichum caucasicum is currently known from, Armenia, Georgia, Russia, and Turkey, but is probably present in the whole forested area in the Caucasus and adjacent areas.	en	Ekrt, Libor, Jessen, Stefan, Novák, Pavel, Vejvodová, Kateřina, Kalníková, Veronika, Lustyk, Pavel, Fraser-Jenkins, Christopher R. (2025): Polystichum caucasicum sp. nov. (Dryopteridaceae), a new, surprisingly hexaploid fern species from the Caucasus. Phytotaxa 736 (3): 275-287, DOI: 10.11646/phytotaxa.736.3.4, URL: https://doi.org/10.11646/phytotaxa.736.3.4
FF513D428D13FF9DFF4FFDCBFAE5A855.taxon	description	Habitat: — The new species was observed to be terrestrial growing in the undergrowth of beech, maple, ravine or alluvial forests in humid, shady and semi-shady conditions. For details see chapter Vegetation notes.	en	Ekrt, Libor, Jessen, Stefan, Novák, Pavel, Vejvodová, Kateřina, Kalníková, Veronika, Lustyk, Pavel, Fraser-Jenkins, Christopher R. (2025): Polystichum caucasicum sp. nov. (Dryopteridaceae), a new, surprisingly hexaploid fern species from the Caucasus. Phytotaxa 736 (3): 275-287, DOI: 10.11646/phytotaxa.736.3.4, URL: https://doi.org/10.11646/phytotaxa.736.3.4
FF513D428D13FF9DFF4FFDCBFAE5A855.taxon	etymology	Etymology: — From the Latin caucasicus, which refers to the fact that this taxon is distributed prominently in the region around the Caucasus. Notes: — Other ferns from the family Dryopteridaceae that occur commonly with Polystichum caucasicum include Dryopteris affinis agg., D. caucasica, D. dilatata, D. filix-mas, Polystichum aculeatum and P. setiferum.	en	Ekrt, Libor, Jessen, Stefan, Novák, Pavel, Vejvodová, Kateřina, Kalníková, Veronika, Lustyk, Pavel, Fraser-Jenkins, Christopher R. (2025): Polystichum caucasicum sp. nov. (Dryopteridaceae), a new, surprisingly hexaploid fern species from the Caucasus. Phytotaxa 736 (3): 275-287, DOI: 10.11646/phytotaxa.736.3.4, URL: https://doi.org/10.11646/phytotaxa.736.3.4
