Asplenium auritum Sw.

  • Authority

    Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.

  • Family

    Aspleniaceae

  • Scientific Name

    Asplenium auritum Sw.

  • Description

    Species Description - Rhizome suberect; rhizome scales brown, clathrate, 3-4 mm long, 1-1.3 mm wide, often stuck together, entire; fronds clumped; stipe 612 cm long, 1/3-½ the frond length, green to brownish-green, glabrous or with rare to sparse scales, 0.8-1 mm long, channelled in larger specimens, non-alate or very narrowly alate; blade narrowly deltate, 11-40 cm long, 3-12 cm wide, once-pinnate, apex pinnatifid, non-proliferous; rachis similar to stipe, alate with 0.5 mm wing; pinnae 12-20 pairs, narrowly lanceolate, 2-5 (-6) cm long, 0.5-1.2 cm wide, petiolulate (14 mm), long attenuate to obtuse, only slightly auricled on acroscopic side, margin sharply bidentate, texture firm, chartaceous to coriaceous, with rare to scattered, 0.5-1 mm long, hairlike, clathrate scales, especially in pinna axils, scattered clavate hairs on abaxial veins; veins obscure, once-forked, not reaching margin, hydathodes prominent; sori 4-8(-12) pairs; indusium 3-4 mm long, 0.3-0.5 mm wide, whitish, entire; spores reniform, tan, 64 per sporangium.

  • Discussion

    Type. Jamaica. Swartz s.n. (S). The Asplenium auritum complex, which in Oaxaca includes A. auritum, A. lacerum, A. cuspidatum, A. monodon and A. sphaerosporum, is in great need of modem biosystematic study. The treatment here essentially follows that of A. R. Smith (1981). Morton and Lellinger (1966) treat this complex as two species, A. auritum (with six varieties) and A. cuspidatum (with five varieties). Until hybridization studies are made, the division of this complex into somewhat arbitrary groups based mainly on frond dissection and spore type will have to stand. The frond dissection series seen in A. auritum (once-pinnate with superior auricle or not), A. lacerum (deeply pinnate-pinnatifid to bipinnate with dentate segments) to A. cuspidatum (bipinnate-pinnatifid to tripinnate) is roughly paralleled in the dissection series seen in A. monodon (once-pinnate with superior auricle to pinnate-pinnatifid at base) to A. sphaerosporum (bipinnate at base of blade). Asplenium monodon and A. sphaerosporum differ from the first three species in having globose, blackish spores numbering only 32 per sporangium (indicating some sort of apomixis) compared with the tan to brown, reniform spores, numbering 64 per sporangium. A. R. Smith (1981) placed the type of A. lacerum and A. mexicanum Martens & Galeotti in the more highly dissected category with A. cuspidatum (and hence adopts A. pyramidatum as the oldest name for the middle category), whereas in this work they are considered to fall in the pinnate-pinnatifid to bipinnate category and A. lacerum becomes the oldest name for this category. All five of the taxa are basically epiphytic (occasionally epipetric) but occur at somewhat distinct elevations in Oaxaca [as is the case in Chiapas (A. R. Smith, 1981)]. Asplenium auritum was found at elevations of 100-600 m, A. lacerum at 750-1450 m, and A. cuspidatum at 900-2700 m, whereas A. monodon was collected at 100-1550 m and A. sphaerosporum at 650-900 m.

  • Distribution

    Epiphytic or epipetric in wet to dry forests; Ixtlán, Juchitán, Tuxtepec; 100-600 m. Range uncertain: Mexico (at least Oax, Chis); Guat to Pan; Jam, Trin; Col to Guy.

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