Paspalum repandum ( Nees 1829: 98 ) G. H. Rua & Valls, 2012

Rua, Gabriel H. & Valls, José Francisco M., 2012, On the taxonomic status of the genus Thrasyopsis (Poaceae, Panicoideae, Paspaleae): new combinations in Paspalum, Phytotaxa 73 (1), pp. 60-66 : 64-65

Paspalum repandum ( Nees 1829: 98) G. H. Rua & Valls , comb. nov.

Basionym:— Panicum repandum Nees (1829: 98) . Thrasyopsis repanda (Nees) Parodi (1946: 297) . TYPE:— BRAZIL. “Brasilia australiore”, Barra do Pará (as “Bra. do Paxa”), date unknown, Sellow B.1246. C.194 (Holotype: B [barcode] B 10 0249432 digital image!; isotypes: BAA [barcode BAA00000622] fragment ex B!, US [barcode US 00139930 p.p.] fragment ex B, digital image!; probable isotypes: G [barcodes G00168437, G00168438 and G00168439] digital images!, K [barcodes K000643320 and K000643322] digital images!, LE, P [P02328829 and P02328833] digital images!, US [barcode US 00139930 p.p.] fragment ex LE, digital image!, W [W0030638] digital image!).

Cespitose perennials with erect culms. Leaf sheaths hirsute, fibrous and persistent after senescence, leaf blades flat, flexuous, pale, silvery-hirsute. Racemes paired or solitary, 1.5–4 cm long, with rachis narrowly winged, not covering the spikelets. Spikelets paired, subglabrous, lower glumes 5–7-nerved, up to ¾ the length of the spikelets; upper glumes obovate, cucullate, 11-nerved; lower floret usually male, the lower lemma 9-nerved, glume-like; upper floret bisexual.

Distribution, habitat, and conservation status: ―Endemic from the Brazilian states of Minas Gerais, São Paulo (most ancient collections known from both states), and Paraná. This species has been consistently collected near Ponta Grossa (state of Paraná) in the vicinity of Vila Velha ( Burman 1983). Nevertheless, we have recently conducted intensive field collections in this area and only found a single tuft. Although the current conservation status of this species has not yet been established, it is very likely to be a threatened species, because of its extreme rarity. Flowering of Paspalum repandum seems to be fire-dependent, since all known herbarium specimens are burned plants.

Additional specimens examined: ― Paspalum repandum . BRAZIL. Paraná: Ponta Grossa , Faz. Vila Velha, BR-367, km 520, borda de barranco com arenito, elev. 915 m, 25º15’56”S, 49º58’50”W, 12 February 2006, Rua s.n. ( CEN) ; id., 13 November 2010, Carmo et al. 22 ( HUPG) ; Vila Velha , 26 November 1952, Araujo 174 ( BAA) .

Nomenclatural notes: ―There are two descriptions for this species published in 1829: Panicum repandum Nees in Martius, Flora Brasiliensis seu Enumeratio Plantarum 2(1): 98–99, and Panicum repandum Nees ex Trin. , Species Graminum 2(13): t. 150. The first work was published between March and June 1829, whereas the exact date of publication of the part 13 of Species Graminum is still unknown ( Stafleu & Cowan 1986), so that it is impossible to know which of both publications is earlier. The original material on which the species was described was collected by Sellow in southern Brazil and originally deposited at B, where it was studied by Nees [“Habitat in Brasilia australiori. (Sellow. Vidi in Herb. Reg. Berol.)”, cf. Nees 1829: 99]. The specimen still conserved at B [barcode B 10 0249432] has a label in Sellow’s handwriting with the inscription “Bra. do Paxa, B 1246, c.194”, without indication of date. There is no place in Brazil with the name “Paxa”, and probably there is a handwriting mistake in Sellow´s label. Between 1814 and 1831, Sellow made six collection trips in Brazil. In the third trip across Minas Gerais, São Paulo and Rio de Janeiro, he double-numbered the specimens from about 2,500 locations under the letters B and c ( Urban 1893), thus the type material of P. repandum belongs to this collection. The itinerary of Sellow’s trips detailed by Urban (1906: 105-112) casts light on the actual locality and date of collection: Sellow was in December 1818 in a place named “Barra do Pará ”, i.e. the mouth of the Pará river in the São Francisco river, near the present town of Pompeu, in the state of Minas Gerais, and this is probably the locality where the plant was collected.

Trinius, who explicitly attributed the species to Nees, based his description and illustration on a sheet deposited at LE (LE-TRIN-0922.01), and labelled “ Panicum repandum Nees ab Ess., Sellow, Brasilia, de Schlechtendal 27” (R. Soreng, pers. comm.). This specimen (not seen) is presumably a duplicate of the original Sellow’s material sent to Trinius by Schlechtendal. The hypothesis of Soreng that this specimen belongs to a collection of cultivated material from seeds of the Sellow plant (pers. comm., see also the entry for P. repandum in Tropicos.org ( Missouri Botanical Garden 2012): “ F. Sellow; cult. coll. de Schlechtendal 27; Brasilia, cult. in Germany ”) seems improbable, because it is a plant difficult to bring into flower under cultivation since flowering seems to be fire-dependent (see above).

As exact publication dates of Trinius work are uncertain ( Stafleu & Cowan 1986: 495), we prefer, in agreement with Soreng (comm. pers.) to take the Nees description (and the corresponding holotype at B) as the valid one, and consider Panicum repandum Nees ex Trin. as an isonym.

Further duplicates of the Sellow’s collection were apparently distributed to several herbaria (G, K, P, W) by Schlechtendal, each specimen identified as Panicum repandum Nees in Schlechtendal handwriting on a label printed with the inscription “ Herb. Reg. Berolinense. Brasilia. Sellow legit.”, with no reference to numbering nor locality. On the other hand, fragments at BAA and US were taken directly from B by Lorenzo R. Parodi and M. Agnes Chase respectively, who transcribed the original Sellow’s label. Further, a specimen at HAL that was indicated erroneously as the type of Panicum repandum (barcode HAL0063595, digital image!) corresponds to the species Paspalum erianthum Nees ex Trinius (1826: 121) . This specimen has two labels in Schlechtendal handwriting, probably dated after Schlechtendal moved to Halle in 1833: one of the labels includes the proper identification followed by a latin description beginning with the expression Panicum repandum spicam …, the other label reads “ Panicum repandum N. ab E. Sellow. Brasilia…”