Hypodematium confertivillosum J.X.Li, F.Q.Zhou & X.J.Li, 2018

Li, Xiaojuan, Li, Jianxiu & Meng, Fanyun, 2018, A new species of Hypodematium (Hypodematiaceae) from China, PhytoKeys 92, pp. 37-44 : 38-39

Hypodematium confertivillosum J.X.Li, F.Q.Zhou & X.J.Li sp. nov.

Diagnosis.

Hypodematium confertivillosum J. X. Li, F. Q. Zhou & X. J. Li is similar to H. crenatum (Forssk.) Kuhn & Decken and H. glanduloso-pilosum (Tagawa) Ohwi, from which it differs greatly by its abaxial fronds sparsely covered with rod-shaped glandular hairs, its adaxial fronds without rod-shaped glandular hairs and spore reniform, with verrucate processes, surface with distinct finely lamellar rugae ornamentation.

Type.

China. Shandong Province: Linyi City, Fei County, Tashan Mountain , limestone rocks, 35°33'59.76"N, 117°51'29.51"E, 500-700 m a.s.l., 15 September 1982, J. X. Li 02025 (Holotype: PE, Isotype: SDCM). Figure 1 .

Description.

Plants 21-32 cm tall. Rhizomes creeping; densely scaly together with stipe base, scales reddish-brown, lustrous, linear-lanceolate, 10-12 × 1-2 mm, membranaceous, margin subentire, apex acuminate. Fronds approximate; stipe stramineous, 7-17 cm × 1-1.2 mm, nearly glabrous upward; laminae pentagonal, 12-17 × 12-14 cm, 3-pinnate-pinnatifid, base round-cordate, apex acuminate and pinnatifid; pinnae 10-12 pairs, slightly oblique, lower 2 pairs sub-opposite, 3-4 cm apart, upper pairs alternate; basal pinnae largest, deltoid-oblong, 10-11 × 8-8.5 cm, 2-pinnate-pinnatifid, base cordate, pinnae tapered; pinnules 6-8 pairs, anadromous, alternate, slightly oblique, acroscopic ones smaller, proximal basiscopic pair largest, ovate-triangular, 5 × 2-3 cm, shortly stalked, base cuneate, pinnae tapered, pinnate-pinnatifid; ultimate pinnules oblong, 8-10 × 4-6 mm, apex obtuse, pinnatifid; lobe oblong, apex obtuse, margins obtuse-serrate; second and upper pairs of pinnae gradually shorter, lanceolate or oblong-lanceolate, 2-pinnate-pinnatifid, base rounded-cuneate or shal lowly cordate, with a short stalk, apex shortly acute. Veins obvious on both surfaces, pinnate, simple, ending at margin. Laminas chartaceous, fronds densely covered with long grey hairs adaxially, fronds abaxial surface, rachis and costae densely covered with long grey hairs and sparsely mixed with rod-shaped glandular hairs. Sori round, dorsal, 1-4 per segment; indusia reniform, pale grey, membranaceous, densely covered with grey hairs. Spores reniform, with verrucate processes, surface with distinct finely lamellar rugae ornamentation.

Distribution.

This species is known only from the area around the type locality in Tashan, Shandong.

Ecology.

Usually growing in limestone crevices of xeric areas.

Discussion.

The perispore is an important trait for identifying species under the scanning electron microscopy ( Liu and Li 1999) and it contributes to the discovery of some new species, for example Dryopteris guanchica ( Jermy 1980). There are significant differences between the perispore of H. confertivillosum that has verrucate processes, surface with distinct finely lamellar rugae ornamentation, H. crenatum having curved long ridges, surface with fine striae ornamentation and H. glanduloso-pilosum having tuberculate-massive ornamentation, providing an important micromorphological basis for establishment of the new species H. confertivillosum . A comparison of H. confertivillosum , H. crenatum , and H. glanduloso-pilosum is given in Table 1 and Figure 2 .

It is commonly believed that Hypodematium , a very special group, has different types of glandular hairs and non-glandular hairs, which is an important basis for the identification and classification of species of Hypodematium ( Zhang and Iwatsuki 2013). Hypodematium confertivillosum fronds are sparsely covered with rod-shaped glandular hairs abaxially, but its adaxial fronds without rod-shaped glandular hairs; H. crenatum fronds are sparsely covered with acicular hairs adaxially, densely covered with long hairs abaxially and without rod-shaped glandular hairs on both surfaces. Hypodematium glanduloso-pilosum fronds are mixed, densely covered with acicular and rod-shaped glandular hairs adaxially and long hairs and rod-shaped glandular hairs abaxially. Therefore, the types of hair and the degree of density of different types of hair support the establishment of the new species of H. confertivillosum . A comparison of H. confertivillosum , H. crenatum , and H. glanduloso-pilosum is given in Table 2 and the taxonomic key below (adapted from Zhang and Iwatsuki 2013), and Figure 3 .

Figures

Figure 1. Hypodematium confertivillosum J. X. Li, F. Q. Zhou & X. J. Li, sp. nov. A Habit B Sori on the abaxial surface of pinnules C Indusium with long hairs D Rhizome and stipe base scales E Long hairs from the abaxial surface of fronds F Rod-shaped glandular hairs from the abaxial surface of fronds G Hairs from the adaxial surface of fronds (Drawn by Y. B. Sun & J. X. Li).

Figure 2. Spore morphologies of three Hypodematium species (SEM). A Spore in equatorial view of H. confertivillosum (1500 x) B Detail of spore in equatorial view of H. confertivillosum (5000 x) C Spore in polar view of H. confertivillosum (1500 x) D Detail of spore in polar view of H. confertivillosum (5000 x) E Spore in equatorial view of H. crenatum (1500 x) F Detail of spore in equatorial view of H. crenatum (5000 x) G Spore in equatorial view of H. glanduloso-pilosum (1500 x) H Detail of spore in equatorial view of H. glanduloso-pilosum (5000 x).

Figure 3. The fronds and rachis of H. confertivillosum, H. crenatum and H. glanduloso-pilosum (SEM). A H. confertivillosum fronds densely covered with long hairs adaxially (30 x) B H. confertivillosum fronds and indusia densely covered with long hairs and sparsely rod-shaped glandular hairs abaxially (30 x) C H. confertivillosum fronds and costae densely covered with long hairs and sparsely rod-shaped glandular hairs abaxially (30 x) D H. confertivillosum costae densely covered with long hairs and sparsely rod-shaped glandular hairs abaxially (160 x) E H. crenatum fronds sparsely covered with acicular hairs adaxially (60 x) F Close-up view of H. crenatum fronds covered with acicular hairs adaxially (140 x) G H. crenatum fronds and indusia densely covered with long hairs abaxially (30 x) H Close-up view of H. crenatum indusia covered with long hairs abaxially (60 x) I H. glanduloso-pilosum fronds densely covered with acicular hairs and rod-shaped glandular hairs adaxially (30 x) J Close-up view of H. glanduloso-pilosum fronds covered with acicular hairs and rod-shaped glandular hairs adaxially (140 x) K H. glanduloso-pilosum fronds and indusia densely covered with long hairs and rod-shaped glandular hairs abaxially (30 x) L Close-up view of H. glanduloso-pilosum fronds covered with long hairs and rod-shaped glandular hairs abaxially (140 x)