Bothriochloa catharinensis E. Dalmolim & A. Zanin, 2014

Dalmolim, Emilaine Biava & Zanin, Ana, 2014, A new species of Bothriochloa (Poaceae, Andropogoneae) endemic to montane grasslands of Santa Catarina, Brazil, Phytotaxa 183 (1), pp. 44-50 : 45-49

Bothriochloa catharinensis E. Dalmolim & A. Zanin , sp. nov. ( Figs. 2–3 )

It differs from the other species of the genus, with which it shares an elongated central axis of the inflorescence, nodes of the culm glabrous and sessile spikelet awnless and without foveola, mainly by the combination of panicle rhombic to oval, open, with branches divergent from the rachis, axils of the branches pilose, branches moderately pilose, with trichomes not hiding the sessile and pedicellate spikelets and internodes of the rachis and pedicels with a markedly purplish to black groove.

Type:— BRAZIL. Santa Catarina: Bom Jardim da Serra, Parque Nacional de São Joaquim , 1282 m, 28º13’05.9”S, 49º35’38.7”W, 23 March 2012, E. Dalmolim & A. Zanin 182 (holotype FLOR!, isotypes FLOR!, ICN!, K!) .

Perennial plants, 0.6–0.7 m tall, herbaceous, caespitose, semi-decumbent; culms glabrous, nodes brown to dark brown glabrous; sheaths glabrous; ligule 1–1.3 mm long, membranous, sometimes membranous-ciliolate, slightly obtuse, dorsum glabrous; ligular region with sparse trichomes 3–5 mm long, occasionally glabrous; blades 2.5–13 × 0.2–0.6 cm, flat, green, becoming purplish when old. Panicle 5–9.5 cm long, open, rhombic to ovate, white-silky, main rachis longer than the branches, branches diverging from the rachis, primary branches alternate, sometimes subopposite to opposite at the base, with dense to subdense trichomes in the axils eventually extending along the margins, flowering branches moderately pilose, not hiding the spikelets sessile and pedicellate. Rachis internode 2.5–3 mm long, enlarged towards the apex, with purplish to black groove, rarely light brown in the same plant, wider than the margins, sometimes without distinction between the groove and margins, these with subdense trichomes, 0.5–6.5 mm long, longer towards the apex. Pedicels 2.5–3 mm long, similar to the internodes in groove, color and vestidure. Pedicellate spikelet 2.5–3.3 mm long, sterile, scabrous, callus glabrous. Sessile spikelets 3.5–3.8 mm long, bisexual, not pitted; callus pilose; lower glume 3.5–3.8 mm long, 4–6–nerved, with sparse trichomes on the lower 2/3, scabrous on keels toward the apex, apex bifid; upper glume 2.8–3 mm long, 3–nerved, scabrous on main keel towards the apex, ciliated margins in the upper half, apex mucronate; lower lemma 1.5–2 mm long, sterile, hyaline, apex obtuse to subacute; lower palea absent; upper lemma 1.5–2 mm long, hyaline, awn (11–) 12–14 mm long, geniculate, column twisted, scabrous, brown; upper palea usually absent, if present vestigial, hyaline, glabrous. Lodicules 0.4–0.6 mm long, hyaline, truncate to lobed. Stamens 3, anthers 0.5–0.8 mm long, brown. Caryopsis 2–2.2 mm long, elliptic, brown.

Etymology:— the epithet catharinensis refers to the state of Santa Catarina, Brazil, where the type collection was collected and the single known geographical area for the species until this moment.

Similarities to other species of Bothriochloa : — based on morphological and cytological characters the American species of Bothriochloa are usually allied to two complexes ( Scrivanti et al. 2009): the Bothriochloa barbinodis complex, with sessile spikelets longer than 5 mm, long awns and lower glume with glandular pits (foveola) present, and the Bothriochloa saccharoides complex, with sessile spikelets shorter than 5 mm, short awns and foveola absent ( De Wet 1968; Allred & Gould 1983). Bothriochloa catharinensis presents morphological characteristics that place it in the B. saccharoides complex. Amongst species in the complex, Botrhiochloa catharinensis resembles most significantly B. laguroides , B. longipaniculata ( Gould 1955: 18) Allred & Gould (1983: 180) and B. torreyana ( Steudel 1840: 93) Scrivanti & Anton (2011: 156) . Attributes that distinguish the new species comprise a combination associated in particular with the structures of the panicle; however, some vegetative differences are also observed. Bothriochloa longipaniculata includes larger plants with longer panicle than in B. catharinensis (panicle: (9–) 13.5–20 cm and 5–9.5 cm, respectively; plant height: (60–) 80–175 cm and 60–70 cm, respectively). In B. laguroides the ligule is longer, often more than 2 mm long, reaching 6.2 mm ( Marchi & Longhi-Wagner 1998), while in B. catharinensis it reaches 1–1.3(–1.5) mm. Differences in the length of the anthers are observed between B. catharinensis and B. torreyana , being 0.5–0.8 mm and 0.8–1.2(–1.4) mm long, respectively. Bothriochloa catharinensis differs markedly from the two species by its panicle rhombic to ovate, open, with branches divergent from the rachis, with a tuft of trichomes in the axils of the branches, characters very evident in the field. In addition to these characters the flowering branches also stand out, with less dense pubescence that does not hide the sessile and pedicellate spikelets and the internodes of the rachis and pedicels with markedly purplish to black grooves. The dark coloration of the internodes and pedicels stands out in the field and dehydrated material, visible to the naked eye; it was observed in both sites in different years.

Micromorphology of the surface of the fruit:— Besides Bothriochloa catharinensis , the genus is represented in PARNA SJ by B. laguroides . The macro-morphological similarities and differences between these two species have already been discussed above. However, the micromorphology of the surface of the caryopsis of these species was also observed by SEM and some other differences, especially in the thickness and sinuosity of the longitudinal walls of the cells, became evident. In B. laguroides the longitudinal walls are slender (2.9–3 µm), showing a pattern of gentle swelling, rarely with verrucose projections ( Fig. 3G ). In B. catharinensis , on the other hand, the longitudinal walls are thicker (3.6–4.7 µm) and have more significant sinuosities in a zigzag pattern, often with verrucose projections at angles ( Fig. 3F ). This variation has also been reported in the micromorphology of the fruit surface of species of Andropogon Linnaeus (1753: 1045) occurring in Brazil ( Zanin & Longhi-Wagner 2001).

Distribution, habit, phenology:— Bothriochloa catharinensis is known so far only from two sites occurring in PARNA SJ in the southern plateau of the state of Santa Catarina, which is in the Atlantic Forest Biome IBGE (2004). The PARNA SJ is located in a large area developed on the continental crust filled with sedimentary and volcanic rocks between 350 and 1822 m elevation ( Souza 2004). The specimens are located at 1282–1288 m elevation, characterized by a mosaic of Floresta Ombrófila Mista, known as araucaria forest, due to the presence of Brazilian pine Araucaria angustifolia ( Bertoloni 1819: 411) (Kuntze 1898: 375) associated with extensions of montane grasslands and nebular forest. The two sites were found in Bom Jardim da Serra, on road margins and also advancing into the road that cuts through the park connecting this municipality to the municipality of Urubici near the Pelotas River, one of the sites situated about 25 m from the river bank. The plants occur on dry soil. Both populations were found in flower and fruit only in March, and the first one, found in 2012, had disappeared the following year, probably due to being in an unprotected place, subject to trampling.

Conservation:— Bothriochloa catharinensis is known from only two sites occurring in a limited area of PARNA SJ. Although the populations are located in a government protected area, its habitat, on the roadside, is very vulnerable since there is regular movement of vehicles and road maintenance crews. According to IUCN (2013) criteria the species is classified as Critically Endangered (CR), based on the criteria B2b(i,ii,iii)+D.

Additional material examined (paratype):— BRAZIL. Santa Catarina: Bom Jardim da Serra, Parque Nacional de São Joaquim, estrada dentro do Parque Bom Jardim da Serra-Urubici , 1288 m, 28º13’45.7”S, 49º36’05.8”W, 23 March 2013, E. Dalmolim & A. Zanin 208 ( FLOR!, RB!) .

Figures

FIGURE 2. Bothriochloa catharinensis (E. Dalmolim & A. Zanin 182—FLOR). A. habit; B. detail of the central axis of the inflorescence showing a tuft of trichomes in the axil of the branch; C. rachis internode; D. grooved pedicel and pedicellate spikelet; E. diaspore; F. upper lemma of sessile spikelet; G. caryopsis, dorsal view; H. pedicel and pedicellate spikelet; I. rachis internode; J. diaspore. Illustrations by Leandro Lopes.

FIGURE. 3. A–F. Bothriochloa catharinensis (E. Dalmolim & A. Zanin 182). A, E. panicle; B. basal floriferous branch of the panicle; C. base of the plants; D. habit; F. B. catharinensis, SEM photomicrograph of the surface of the fruit - arrows showing verrucose projections; G. B laguroides (E. Silva e Silva & A. Zanin 97—FLOR) - SEM photomicrograph of the surface of the fruit. Photos by A. Zanin and E. B. Dalmolim.