Sticherus albus J.Gonzales, 2011

Gonzales, Jasivia & Kessler, Michael, 2011, A synopsis of the Neotropical species of Sticherus (Gleicheniaceae), with descriptions of nine new species, Phytotaxa 31, pp. 1-54 : 14-16

Sticherus albus J.Gonzales , sp. nov. ( Fig. 7 )

Rhachis crassa , squamis persistentibus, aphlebiis trimeris provisa, perfecte pectinata. Gemma apicalis magna, perspicue squamata. Indumentum segmentorum paginae abaxialis densum (praecipue ad costam, sparse ad venulas), squamae longe lanceolatae, concolores pallide aurantiacae, hyalinae, membranaceae, cellulis rectangularibus ad linearibus, apice fimbriata, marginibus ciliatis.

Type: — ST. VINCENT. Richmond Peak , Morne Garou Mountains, 900–1050 m, 15 April 1947, C. V. Morton 4946 (holotype US!).

Rhizomes unknown. Petioles 3–5 mm thick, castaneous. Rachises ca. 15 cm long between pinnae, the scales large, pale orange; aphlebiae trifoliate. Fiddleheads l.5–2.0 cm in diameter, covered with large and usually concolorous pale orange scales. Buds large, ascending and opening rapidly, the scales narrowly-long lanceolate, basally rounded, apically fringed, 2.5–4.0 × 0.5–0.8 mm, gradually bicolorous, brown to matte with whitish margins, usually the darkened cells are restricted to the bases but sometimes found in the scale center, the margins translucent with numerous, delicate cilia 1/8 of the scale length, rigid, translucent, basally usually darkened, the cells hexagonal to linear, forming a linear to ill-defined texture; the shape and size of the bud scales are quite consistent in a given plant. Pinnae 35–40 cm long, 2–3-forked, 1 st branch 3.5–6.0 cm long and 2–3 mm thick, usually shorter than the 3 rd, not pectinate, 2 nd branch 5–6 cm long and 2.0– 2.5 mm thick, pectinate, usually with short aphlebiae, 3 rd and distal branch (10–) 25–30 cm long and 1.0– 1.5 mm thick, pinnatisect, 4–7 cm wide with segments, lanceolate, with 2.5–3.0 segments per cm, proximal internal segments gradually reduced and overlapping; scales adaxially mixed, one type stellate, 0.1 mm in diameter, lax, the margins with a few cilia 1–2 times the scale length, the second type linear, ca. 2.0 × 0.1 mm, the margins with few, short cilia; abaxially and laterally densely scaly, the scales lanceolate, basally shortened, apically fringed, 1.5–3.0 × 0.2–0.6(–1.0) mm, the shorter ones usually on the abaxial surfaces and the larger and narrower ones lateral, pale orange, the margins with unequal and thin cilia 1/10 of scale length, cell texture matte-translucent, the cells narrowly hexagonal to linear, sometimes ill-defined, forming vermiculate surfaces. Segments 2.5–4.5 cm × 2.0– 2.5 mm, linear, semi-chartaceous with margins narrowly revolute; adaxially glabrous; abaxially with slightly raised veinlets, glabrous or sparsely scaly, the scales spreading, lax, stellate, whitish, translucent; midveins densely scaly, the scales proximally linear-lanceolate and distally round-lanceolate, apices long-fringed, 0.8–1.5 × 0.2–0.5 mm, pale orange, the margins with straight, thin cilia 1/4 of length of scale, cell texture translucent with rectangular to irregular cells. Sori medial, not reaching the segment apices, not nested within scales, 10–15 pairs per segment, 3–5(–6) sporangia per sorus.

Distribution and ecology:— Mountains of Honduras (900–2000 m) and the Caribbean islands of St. Kitts, Nevis, Guadeloupe, Dominica, Martinique, St. Vincent, and Grenada (600–1100 m). Locally common in humid montane forests, often found in mossy ridge forests and along banks.

Specimens examined (paratypes): — HONDURAS. Morazán: Cerro de Uyaca, 900–1100 m, 31 March 1951, Morton 1556 ( US); La Tigra, 20 km NE of Tegucigalpa, 2000 m, 13 May 1984, López 183 (NY). ST. KITTS AND NEVIS. Mount Misery , 8 September–5 October 1901, Britton 526 ( NY, US) ; Nevis Peak, 900– 1095 m, 11 April 1956, Proctor 10548 ( BM, US). GUADELOUPE. 1862, L'Herminier 222 ( B, G, GH); 1100 m, 2 November 1937, Stehlé 2415 ( US) . DOMINICA. Morne Micotrin, 600 m, 17 February 1966, Chambers 2746 ( BM, GH, MO, US). MARTINIQUE. L'Aileron, Mt. Pelée , 850–950 m, 8 December 1960, Proctor 21742 ( GH) . ST. VINCENT. Charlotte, Soufriere Mt., above Rabacca , 650–950 m, 21 January 1962, Cooley 8212 pp ( NY, S, US) . GRENADA. October 1890 – May 1891, Sherring s.n. ( BM) .

Notes:— This species is characterized by a combination of thick branches, fully pectinate, broadly lanceolate distal branches, dense, persistent scales on the rachises, large, trifid aphlebiae, large fiddleheads with conspicuous scales, dense indument abaxially on the segments, densely scaly midveins, and sparse scales on the veinlets. The scales are mostly elongate-lanceolate with fringed apices, concolorous, pale dull orange, translucent with rectangular to linear cells, and densely ciliate margins. Some bud scales have darkened bases. Sticherus albus is most similar to S. pallescens in general aspect and scale pattern, but the latter has glabrous ultimate and penultimate branches, relatively broader scales, and narrower midvein scales. Sticherus albus also resembles S. tomentosus because of its large size, scales, aphlebiae, and scale texture, but S. tomentosus has a much denser indument abaxially, more prominent veinlets, larger, darker midvein scales, and mostly bicolorous scales.

In herbaria, specimens of S. albus have usually been identified as Sticherus furcatus . However, we here apply that name to another species, leaving the present taxon without a name.

The disjunct geographical distribution of S. albus is striking and has caused us to question our species delimitations. However, morphologically the Antillean and Honduran specimens are essentially identical, and long-distance spore dispersal from the Caribbean islands to the adjacent mainland, or vice versa, is not out of question.

Figures

FIGURE 7. Sticherus albus. A. abaxial branch scales; B. bud scales; C1. midvein scales; C2. linear midvein scales; D. veinlet scales. Morton 4946. Scale bars in A–C2 are all 0.5 mm long.