Trichosteleum glaucinum (Besch.) A.Jaeger

Gradstein, S. Robbert & Bernard, Elisabeth Lavocat, 2020, An evaluation of the endemic bryophyte flora of Guadeloupe, Cryptogamie, Bryologie 20 (15), pp. 205-214 : 207-209

Trichosteleum glaucinum (Besch.) A.Jaeger

( Fig. 5 )

Berichte über die Thätigkeit der St. Gallischen Naturwissenschaftlichen Gesellschaft 1876-1877: 416 (1878). — Basionym: Rhaphidostegium glaucinum Besch., Annales des Sciences naturelles, Botanique, sér. 4, 3: 253 (1876). — Type: Guadeloupe, without locality, l‘Herminier s.n., “in herb. Schimp., no 28” (lecto-, designated here, PC[PC0121060!]; isolecto-, PC[PC0733118!], NY n.v.).

Remarks

According to Buck (1998) T. glaucinum is characterized by oblong-triangular, shortly acuminate leaves with plane to

slightly twisted apices, obscurely serrulate margins, cells with a conspicuous papilla in the upper ⅓, and leaf bases rather abruptly constricted to a narrow insertion. Buck considered T. glaucinum probably most closely related to T. vincentinum (Mitt.) A.Jaeger , a species widely distributed in the West Indies, but the leaves in the latter species are narrower and more longly acuminate, with subulate and more conspicuously twisted apices. Moreover, the leaves are presumably more gradually narrowed to the base.

We have examined the two isotype specimens of Trichosteleum glaucinum in Bescherelle’s “Antillean Bryophytes” herbarium in PC. Both have leaves with shortly acuminate tips and fit the prologue very well. The specimen PC0121060 in this herbarium is chosen as the lectotype as it refers to the Schimper herbarium. A portion of the type kept in the general bryophyte herbarium of Paris (PC0099421!), however, has longly acuminate leaves with twisted, piliferous tips and does not belong to T. glaucinum ; instead it represents typical T. vincentinum . This suggests that the original collection of T. glaucinum may have been a mixture of T. glaucinum and T. vincentinum . A close examination of leaves of the two species showed that the piliferous, twisted tips measured about ¼-⅓ of total leaf length in T. vincentinum and ¹⁄₁₀-¹∕₅(-¼) in T. glaucinum . Moreover, the upper part of the leaf (beyond the widest portion of the lamina) was about twice longer than the lower part in T. vincentinum and only about 1.5× longer in T. glaucinum . We could not confirm the difference in leaf base constriction mentioned by Buck. In both species the leaves seemed to be gradually narrowed to the base. Since the two species essentially differ only in the length of the piliferous tips, T. glaucinum should probably be treated as a variety of T. vincentinum .

According to Buck (1998) Trichosteleum glaucinum is only known from the type from Guadeloupe. Recently, however, the species has been reported from three different states of Brazil: Bahia ( Evangelista et al. 2018), Maranhão (Silva 2018) and Mato Grosso (www.splink.croia.org.br). However, all three Brazilian records appear to be erroneous. According to Dr Denilson Peralta (pers. com.) the material from Maranhão belongs to T. subdemissum (Besch.) A.Jaeger. and that from Mato Grosso to an undescribed species (det. A. Leal & P. Camara). Furthermore, based on images sent by Dr Cid J. P. Bastos we found that the material from Bahia belongs to T. intricatum (Thér.) J.Florsch. It thus appears that T. glaucinum does not occur in Brazil and is endemic to Guadeloupe.

Figures

FIG. 5.— Lectotype ofTrichosteleum glaucinum (Besch.) A.Jaeger (PC-hb.Bescherelle “Antillean Bryophytes”).