Tropical Natural History 14(2): 45-74, October 2014 2014 by Chulalongkorn University The Genera Microsorum and Phymatosorus (Polypodiaceae) in Thailand SAHANAT PETCHSRI1 AND THAWEESAKDI BOONKERD2* 1 Division of Botany, Department of Biological Science, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, THAILAND 2 Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, THAILAND * Corresponding Author: Thaweesakdi Boonkerd ([email protected]) Received: 30 July 2014; Accepted: 5 September 2014 Abstract.– Based on the examination of herbarium specimens and on observations of most Thai species in their natural habitat, an updated account and status of the Microsorum sensu lato (Polypodiaceae) is presented. This includes 11 species of Microsorum Link and four species of Phymatosorus Pic. Serm. The descriptions, distributional and ecological information of all previously recognized taxa have been completed and corrected where necessary. The nomenclatural status and synonyms were thoroughly reviewed with typifications of all names. Determination keys to the species of both genera in Thailand are provided. KEY WORDS: microsoroid ferns, Microsorum, Phymatosorus, revision pinnatly compound lamina and one row INTRODUCTION sunken sori), were excluded from Microsorum in that classification. in her The polypodiaceous fern genus work. Although the generic name Microsorum was established by Link in 1833 Phymatosorus, a genus having sori located based on the type species, M. irregular. This in distinct cavities and appear as small is an old world genus which has a wide tubercles on the upper surface of the lamina distribution in tropical parts of the Old (Pichi Sermoli, 1973), has been quite widely World, extending from the Pacific Islands to adopted by modern pteridologists, such as northeast Australia, Malaysia, Southeast Bosman (1991), some authors still prefer to Asia and southern China, and from the place all species into the more broadly Indian subcontinent to Madagascar and circumscribed genus, Microsorum tropical Africa (Kramer and Green, 1990). (McCarthy, 1998; Nooteboom, 1997; However, the generic delimitation and the Tagawa and Iwatsuki, 1989). Nooteboom taxonomic position of Microsorum is (1997) has confirmed that some of the equivocal and covers unsolved. According diagnostic characters of Phymatosorus, as to Bosman’s monograph (1991), Microsorum interpreted by Bosman, are not as consistent is unique in that the sori are exclusively as Bosman (1981) implied, or were irregularly scattered on simple or pinnatifid interpreted incorrectly. In addition, the lamina or sometimes arranged in two-more application of the terms anadromous and rows, parallel to each secondary vein, or on catadromous is of doubtful value when smaller veins and tertiary veins are applied to areolate venation. Recent studies catadromous. Accordingly, many species, suggested that Microsorum are polyphyletic such as Phymatosorus (epiphytic or and required more investigate to delimit the lithophytic ferns with variously lobed or 1- 46 TROPICAL NATURAL HISTORY 14(2), OCTOBER 2014 boundary of the genus (Schneider et al., – Sori sunk in cavities, forming 1(-2) 2004; Kreier et al., 2008), where some rows per large areole on a soral vein. cryptic genera should be recognized from Frond pinnatifid to pinnately Microsorum membranaceum clade (Kreier et compound………..…2. Phymatosorus al., 2008). In Thailand, most of the 10 currently Genus Microsorum Link species of Thai Microsorum were Microsorum Link, Hort. Berol. 2: 110. established based mainly on material 1833; Bosman, Leiden Bot. Ser. 14: 69. deposited in two major Thai herbaria: BK 1991; Noot., Blumea 42: 294. 1997. and BKF (Tagawa and Iwasuki, 1989). Type: Microsorum irregulare Link (= Since then, large numbers of new Microsorum punctatum). collections from across the country have Dendroconche Copel., Phillipp. J. Sc., Bot. been made, with two new species and two 6: 91. 1911. Type: Dendroconche new records been added to the Thai account annabellae H.O. Forbes (= Microsorum (Boonkerd and Nooteboom, 2001; linguiforme). Boonkerd et al., 2004; Boonkerd, 2006, Myuroteris C. Chr., Dansk Bot. Ark. 6 no. Petchsri et al., 2009) bringing the total 3: 73, t. 9, f. 1-2, t. 10, f. 3. 1929. Type: number of Thai Microsorum up to 14 Myuroteris cordata C. Chr. (= species. In this paper we follow the Leptochilus cordatus (H. Christ) Ching). classification system proposed by Smith et Rhizome: creeping, white waxy or not, al. (2006) who recognized Microsorum and bearing fronds rather closely (or rather Phymatosorus as separated genera. remotely in M. sarawakense), roots sparsely Likewise, Christenhusz et al. (2011) placed to densely set; phyllopodia more or less Microsorum and Phymatosorus in the distinct. Rhizome scales: peltate or subfamily Microsoroideae of Polypodiaceae. pseudopeltate, slightly sparsely to densely covered, appressed to spreading, at least brown to opaque on centre, clathrate MATERIALS AND METHODS throughout or clathrate with hyaline margin, margin entire or dentate to denticulate, This revision is based on the study of ca. central region glabrous or bearing 350 herbarium sheets from BCU, BKF, K, multiseptate hairs. Stipe: sessile or very L, and QBG (abbreviations according to short to long, indistinct from the midrib, Thiers, 2014). Measurements were made on slightly raised to raise on both surfaces or the herbarium materials. In addition, field raise on lower surface and grooved on upper work was performed in some areas of N, surface, green to stramineous or brown; NE, C, W and S Thailand. glabrous to scaly at base. Fronds: simple or pinnatifid to trifoliate, monomorphous or SYSTEMATICS slightly dimorphous, membranaceous to Identification Key thinly herbaceous to papyraceous or subcoriaceous to coriaceous, iridescent blue 1. Sori superficial, not sunk in cavities. or light to dark green or blackish; margin Frond simple to pinnatifid………….1. subentire to entire or undulate, decurrent Microsorum downwards to long wings of stipe or not, covered with glandular hairs, acicular hair PETCHSRI AND BOONKERD — THAI MICROSORUM AND PHYMATOSORUS 47 and/or scale absent. Sori: separate or 5. Rhizome slender, scandent, with sometimes in part confluent, round to fronds far apart………………..…….6 oblong, superficial or slightly immersed, – Rhizome thick, creeping, never forming two irregular rows between scandent………………...…………...7 adjacent veins or irregularly scattered on 6. Rhizome scale round or elliptic, junction of veinlets or simple free included centrally dark, margin hyaline, cells veins, spreading throughout or ½–⅔ of the small, more or less isodiametric........7. lamina surface, existing in all areoles or M. sarawakense absent in the costal and marginal areoles; – Rhizome scale not as above, cells paraphyses absent or uniseriate. longitudinally rectangular towards the The Plant List (2013) includes 36 apex……………………………..9. M. accepted species names and 82 unassessed superficiale species names for the genus Microsorum. Of 7. Lateral main veins distinctly raised at these, 11 are found in Thailand. least on lower surface……..………..8 – Lateral main veins hardly Key to the species visible…………...….6. M. punctatum 8. Sori irregularly scattered, 1. Fronds simple, trifoliate or pinnatifid abundant………..……...……………9 near base, tertiary veins between each – Sori in two regular rows between pair of adjacent veins at most 3……2 adjacent main veins……………11. M. – Fronds exclusively simple, tertiary zippelii veins between each pair of adjacent 9. Stipe distinct, winged to the base. veins at least 3………………...…….3 Lamina thinly herbaceous to 2. Rhizome not waxy. Rhizome scale paperaceous, light to dark green pseudopeltate, central region glabrous. ………...……………...……………10 Frond simple to pinnatifid. Stipe and – Stipe indistinct or absent. Lamina midribs not scaly…………….…2. M. subcoriaceous, light green when insigne living…………...….4. M. musifolium – Rhizome at least sometimes waxy 10 Rhizome scales up to 8 mm long, under the scales or often waxy. clathrate except the hyaline marginal Rhizome scale peltate, central region region, margin entire, central region bearing long hairs. Frond simple to bearing multiseptate hairs at least trifoliate. Stipe and midribs when young. Stipe less than 4.5 mm scaly………..…………5. M. pteropus long, stramineous or greenish, few 3. Living frond iridescent blue- scales at base …….................…..3. M. green………..………...……….…….4 membranaceum – Living frond light green……………..5 – Rhizome scales 1–4.5 mm long, 4. Costa grooved on upper surface; clathrate, margin dentate, central hydathode absent………………10. M. region glabrous. Stipe up to 35 cm thailandicum long, winged nearly to the base, – Costa slightly raised on upper surface; indistinct from the midrib, hydathode distinct on upper stramineous; scaly at base…...….1. M. surface………………..8. M. siamense heterocarpum 48 TROPICAL NATURAL HISTORY 14(2), OCTOBER 2014 1. Microsorum heterocarpum (Blume) Ching Ser. II. 3: 109. 1998. — Polypodium (Fig. 1) heterocarpum Blume, Fl. Jav. Fil.: 167. Microsorum heterocarpum (Blume) Ching, t. 75. 1829. Type: Philippines, Elmer Bull. Fan Mem. Inst. Biol. Bot. 4: 295. 9868 (BM!). 1933; Holttum, Rev. Fl. Malaya 2: 178, Pleopeltis heterocarpa T. Moore, Index f. 87. 1954; Tagawa & Iwatsuki, Filic.: 78. 1857. Type: Java, Blume s.n. Southeast As. St. 3(3): 77. 1965; 5: 52. (holotype L!, photo C). 1967; Fl. Thailand 3(4): 526. 1989; Polypodium zollingerianum Kunze, Bot. Bosman,