Chusquea gouveiensis K.V.A. Vidal & L.G. Clark, 2018

Vidal, Kaio Vinicius De A., Dorneles Welker, Cassiano A., Oliveira, Iasmin Laiane C., Mota, Aline Costa Da, Oliveira, Reyjane P. & Clark, Lynn G., 2018, A new species of Chusquea subg. Chusquea (Poaceae-Bambusoideae- Bambuseae) from Minas Gerais, Brazil: morphological evidence and phylogenetic placement within the Euchusquea clade, Phytotaxa 365 (1), pp. 73-88 : 78-85

Chusquea gouveiensis K.V.A. Vidal & L.G. Clark , sp. nov.

TYPE:— BRAZIL. Minas Gerais: Gouveia, próximo ao entroncamento rodoviário Datas/Gouveia/Diamantina, fragmento de Mata Atlântica à direita da rodovia, ca. 500 m da rotatória (sentido Gouveia-entroncamento), BR-367 , 18º25’13.5’’S, 43º41’38.7’’W, 1322 m, 21 April 2016 (fl), K.V.A. Vidal, C.A.D. Welker, L. Rocha & C.C.S. Bittencourt 213 (holotype HUEFS! , isotypes CEPEC! , NY! , SPF! ). Figs. 1 , 2 .

Diagnosis:— Chusquea gouveiensis differs from C. gracilis mainly by branch complements of 40‒90 usually ascending subsidiary branches (vs. 70‒195 mostly horizontally oriented subsidiary branches), synflorescences weakly paniculate to racemose (vs. paniculate), glumes I and II collectively 0.3‒0.7 mm long (vs. 0.1‒0.2 mm long), and glumes III and IV awned and abaxially pilose to pubescent at the apex (vs. mucronate and glabrous).

Description:—Culms 2‒5 m long, 0.3‒1 cm in diameter, erect at the base to scandent toward the apex; internodes (10‒) 13‒21.7 cm long, terete, vinaceous mottled, with a densely pilose band of trichomes 1.2‒2.2 cm wide present below the nodal line, with recurving trichomes ca. 1 mm long covering the upper 1/4‒1/3 of the internode, otherwise glabrous. Culm leaves 16.2‒20.2 cm long, 2.6‒5.1 cm wide at the base, non-pseudopetiolate, with no differentiation between blade and sheath, inner ligule absent, belatedly deciduous to persistent, adaxially glabrous and shiny, abaxially with a band of trichomes at the base, above this on the lower half sparsely hispid with appressed trichomes, the upper half scabrid, apex acute, mucronate, becoming folded or twisted and sometimes recurved upon drying; girdle ca. 1.5 mm wide, hispid with retrorse trichomes 2‒3 mm long. Nodes at mid-culm with a triangular central bud subtended by 40–90 smaller subsidiary buds in 4‒5 rows, in a constellate arrangement; nodal line dipping slightly below the bud/branch complement, with dense band of pilose trichomes encircling the node and forming a fringe; supranodal ridge visible but not prominent. Branching infra-and extravaginal; subsidiary branches 40‒90 per node, 6‒20 cm long, geniculate at the base to the second or third node, then mostly ascending; floral branches (2.2‒) 2.7‒7.2 cm long, arched or rarely slightly geniculate only in the first node and becoming arched. Foliage leaves (4‒) 6‒15 per complement; sheaths 1‒1.4 cm long, stramineous to faintly purple-spotted, overlapping margin ciliate, with cilia elongated at the apex (1 mm long), the overlapping side of the sheath pubescent between the margin and the keel, keeled toward the apex; outer ligules 0.2‒0.3 mm long, ciliolate, with cilia ca. 0.5 mm long; inner ligules 0.3‒0.5 mm long, membranaceous, truncate, rarely asymmetric, pubescent; pseudopetioles 0.8‒1.1 mm long, hispid-pilose on both sides, pulvinus stramineous to darker brown; blades 2.2‒4.7 cm long, 0.3‒0.45 cm wide, L:W = 7.7‒12 (‒13.3), linearlanceolate, green, not tessellate, adaxially glabrous, the veins forming ridges and those closest to the midrib bearing prickles, abaxially pubescent, trichomes often antrorse, veins not prominent, midrib slightly excentric, more prominent toward the base but visible for almost the entire length, base attenuate, apex acute, margins glabrous basally, usually serrulate on the upper half to the apex. Synflorescences 2‒2.3 cm long, 1.5‒2 cm wide, weakly paniculate to racemose, congested, non-interrupted, subtending spatheate bract absent. Spikelets 6.7‒8.9 mm long, 1.4‒1.7 mm wide, terete; glume I 0.3‒0.5 mm long, ca. 1/20 of the spikelet length, pilose, acuminate, apex mucronate; glume II 0.5‒0.7 mm long, ca. 1/12 of the spikelet length, glabrous with tuft of trichomes at the base, acute, apex mucronate; glumes III and IV membranaceous, 3-nerved; glume III 3.7‒4.3 mm long, ca. 1/2 of the spikelet length, scabrous to pubescent at the base, ciliate toward the apex, apex acute with awn 0.5‒0.8 mm long; glume IV 4‒5 mm long, ca. 3/5 of the spikelet length, scabrous with appressed trichomes at the base, apex long ciliate (cilia ca. 1.5 mm long) with an awn 0.5‒1 mm long; lemma 6.4‒8 mm long, ciliate on the apical 1/3, apiculate, adaxially glabrous with a tuft of trichomes at the apex, abaxially pubescent with appressed trichomes, 5-nerved; palea (5‒) 6‒7.8 mm long, 2-keeled, sulcate from the middle to the apex, mucronate, apex acuminate (more rounded than the lemma) and margins slightly ciliate, abaxially glabrous at the base to scabrous-pubescent to the apex with appressed trichomes. Caryopsis rounded, pericarp bright golden-colored, apex elongated and truncate, forming a slit.

Etymology: —The specific epithet refers to the type locality of this species, the municipality of Gouveia, in Minas Gerais, Brazil.

Taxonomic notes: — Chusquea gouveiensis is similar to C. gracilis in having culm leaves with undifferentiated sheaths and blades with a folded or twisted apex, and foliage leaves and spikelets of similar length. However, C. gouveiensis differs from C. gracilis vegetatively in having culms scandent above the mid-portion and supported on the vegetation (vs. culms erect at the base and apically arched to less frequently scandent) and branch complements of 40‒90 usually ascending subsidiary branches (vs. 70‒195 mostly horizontally oriented subsidiary branches, appearing verticillate). With respect to reproductive characters, the new species has synflorescences weakly paniculate to racemose (vs. paniculate), glumes I and II collectively 0.3‒0.7 mm long (vs. 0.1‒0.2 mm), glumes III and IV awned and abaxially pilose to pubescent at apex (vs. mucronate and glabrous), and lemma longer than the palea (vs. subequal or shorter than the palea) (see Table 4 ).

Distribution, habitat, and conservation: — Chusquea gouveiensis is currently known from only two populations in the municipalities of Gouveia and Diamantina, in the southern part of the Espinhaço Range, in the state of Minas Gerais, Brazil ( Fig. 3 ). The few specimens known were collected in forest fragments near the road, at 1,200 ‒1,300 m.a.s.l. The local flora is rich in trees, with an open canopy and herbaceous substrate, with a number of representatives of Cyperaceae , Fabaceae , and ferns.

Chusquea gracilis is restricted to southern Brazil, occurring in the states of Paraná, Rio Grande do Sul, and Santa Catarina ( Shirasuna et al. 2015) in mixed ombrophilous forest, 550‒ 880 m.a.s.l. ( Schmidt & Longhi-Wagner 2009) ( Fig. 3 ). Mota et al. (2013, 2014a, b) and Ferreira et al. (2009) stressed that factors such as latitudinal distribution, elevation range and habitat often support species delimitation in Chusquea , with which the data herein presented agree.

The forest fragments where Chusquea gouveiensis was collected are suffering anthropic influence. According to the IUCN Red List criteria for species conservation ( IUCN 2016), this species may be considered Critically Endangered (CR) (B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); C2a(i); D), as a result of being known only from two nearby localities, with an EOO (extent of occurrence) estimated to be less than 50 km ², an AOO (area of occupancy) estimated to be less than 10 km ², and a low number of individuals in each population (<50).

Phenology: —During the field trip to the Gouveia region in October, 2011, we did not find flowering individuals. The only flowering event registered for this species occurred in April, 2016. At that time, most individuals were in a mature vegetative stage, but a few culms were flowering, some of them with young or old spikelets and beginning the process of culm death. These data indicate a probable asynchronous flowering in this population.

Additional specimens examined (paratypes): — BRAZIL. Minas Gerais: Gouveia, Serra do Espinhaço, about 8 km N of Gouveia on road to Diamantina , 1220 m, 7 February 1972, Anderson et al. 35659 ( ISC, MO, NY, US) ; Gouveia, BR-259, ca. Km 471‒472, 6.3 km N of Gouveia , 18º25’S, 43º42’W, 1350 m, 27 February 1990, Clark & Morel 713 ( BHCB, ISC, K, MO, NY, SP, US) ; Gouveia, rodovia BR-259 para Gouveia, a 300 m S do trevo de Datas, Planalto de Diamantina , 18º25’04”S, 43º41’30”W, 1266 m, 28 February 1998, Pirani et al. 4054 ( ISC, SPF) ; Gouveia, BR-367 Diamantina-Gouveia, Mata de Capão à direita da rodovia, logo após o entroncamento para Datas , 18º25’13.5’’S, 43º41’38.7’’W, 1322 m, 12 October 2011, Silva et al. 528 ( HUEFS) ; Diamantina, BR-367, de Gouveia a Diamantina , 18º18’S, 43º40’W, 1200 m, 28 March 2008, Viana et al. 3494 ( BHCB, ISC) .

Phylogenetic analyses: —Our combined trees of nuclear (ITS) and plastid (ndhF and trnD-trnT) DNA sequences were congruent in the MP, ML, and BI analyses. The two representatives of subgenera Magnifoliae and Platonia formed an unsupported clade sister to the remaining species of Chusquea (1.0 PP) ( Fig. 4 ). The clade formed by the two species of subgenus Rettbergia (1.0 PP, 100% MLBS, 100% MPBS) emerged as sister to the Euchusquea clade, as previously reported (see Kelchner & Clark 1997, Clark et al. 2007, Fisher et al. 2009, 2014). The Euchusquea clade was well supported (1.0 PP, 97% MLBS, 85% MPBS) and composed of the heterogeneous subgenera Chusquea and Swallenochloa, in accordance with Fisher et al. (2014).

In a tree based on five plastid DNA regions (ndhA, ndhF, rpl16, trnD-trnT, trnT-trnL) and one nuclear region (ITS), Fisher et al. (2014) recovered five moderately to well supported lineages within the Euchusquea clade: I- C. culeou clade (Austral Andes), II- C. ramosissima clade ( Paraguay, Uruguay, Brazil, and Argentina), III- C. uniflora clade (Northern and Central Andes), IV- C. serpens clade (Northern and Central Andes, and Central America), and V- C. scandens clade (Northern and Central Andes, and Central America). In our analysis, however, those clades were not recovered, nor did we find any strongly supported clade that conflicted with them. The use of fewer DNA regions here, as well as somewhat reduced sampling of the extra-Brazilian species of Euchusquea, compared to Fisher et al. (2014), may explain why we did not recover these same clades.

Chusquea ramosissima , for which we sampled only plastid data, emerged as sister to the remaining species of the Euchusquea clade, with weak to moderate support (66% MLBS, 85% MPBS). This relationship contrasts with Fisher et al. (2014), who in their plastid tree recovered C. ramosissima in a clade with C. tenella and C. longispiculata , which they referred to as the C. ramosissima clade. Only C. longispiculata was sampled in their ITS tree ( Fisher et al. 2009, 2014).

Within the Euchusquea clade, we detected a polytomy including the following clades: 1) Chusquea perotensis Clark, Cortés & Cházaro (1997: 225) + C. glauca Clark (1989: 95) (54% MLBS); 2) [ C. gigantea Demoly (1999: 8) + C. uliginosa Philippi (1859: 207) ] + C. quila Kunth (1830: 329) (0.96 PP, 76% MPBS); 3) [ C. coronalis Soderstrom & Calderón (1978a: 158) + C. pittieri Hackel (1903: 153) ] + C. virgata Hackel (1903: 156) (1.0 PP, 75% MLBS, 67% MPBS); 4) C. andina Philippi (1858: 103) + C. culeou Desvaux (1854: 450) (1.0 PP, 100% MLB, 100% MPB) and 5) a large clade with no support including the remaining sampled species of the Euchusquea clade ( Fig. 4 ).

Within this last clade, a large clade (0.95 PP, 73% MLBS, 76% MPBS) is sister to the poorly supported clade composed of Chusquea tenella + C. longispiculata (54% MLBS) and includes two main lineages. One of them (not supported) includes most members of clades III, IV and V of Fisher et al. (2014). Within this large unsupported lineage, however, several relationships emerged with high support, including the following clades: 1) C. foliosa Clark (1986: 115) + C. longifolia Swallen (1940: 210) (1.0 PP, 91% MLBS, 92% MPBS); 2) [ C. costaricensis Clark & March (2000: 6) + C. paludicola Clark (1986: 101) + C. tonduzii Hackel (1903: 155) + C. vulcanalis ( Soderstrom & Calderón 1978b: 309) Clark (1987: 428) (1.0 PP, 86% MLBS, 85% MPBS)] + C. talamancensis Widmer & Clark (1991: 169) (1.0 PP, 99% MLBS, 95% MPBS); and 3) C. antioquensis Clark & Londoño (1998: 423) + C. lehmannii Pilger (1899: 35) (0.99 PP).

The other main lineage is supported in the BI analysis (0.95 PP, 55% MLBS) and encompasses the remaining Brazilian species of Chusquea sampled ( Fig. 4 ). Relationships among some of these species were highly supported in the BI analysis by Fisher et al. (2014), but based on only eight samples. We have increased the number of Brazilian species sampled, which are all part of this clade, and designate this lineage as clade VI- C. meyeriana Ruprecht ex. Döll (1880: 203) clade. Within this clade, C. windischii Clark (1992: 405) , C. leptophylla and a clade comprising the rest of the species (0.95 PP, 60% MLBS) formed a polytomy. Within the latter clade, the following four lineages also formed a polytomy: C. pinifolia ( Nees 1829: 525) Nees (1835: 490) ; a clade including most of the Brazilian species of C. subg. Swallenochloa sampled (three species); C. gracilis ; and a clade (named lineage A) (0.94 PP, MLBS 74%) comprising Brazilian representatives of C. subg. Chusquea , mainly including members of the previously designated C. meyeriana informal group (0.94 PP; MLBS: 74%) ( Fig. 4 ) ( Fisher et al. 2014).

The poorly supported clade (MPBS 77%) formed by Chusquea nudiramea Clark (1992: 415) + one accession of C. mimosa subsp. australis Clark (1992: 414) (sample Mota 343) was recovered as sister to another accession of C. mimosa subsp. australis (0.99 PP, 76% MLBS) ( Fig. 4 ). In Fisher et al. (2014) these relationships were not recovered; rather, C. nudiramea was strongly supported as sister to C. windischii , while C. mimosa subsp. australis formed a polytomy with C. gracilis + C. juergensii Hackel (1909: 325) and C. leptophylla . The present results are consistent with morphological expectations, since C. mimosa subsp. australis and C. nudiramea are part of the C. nudiramea informal group ( Clark 1992).

The Chusquea nudiramea informal group is characterized morphologically by deciduous sheaths of the foliage leaves at the lower nodes, leaving those branches naked (an exclusive character of this group), in addition to the erect habit with the apex slightly arched and subsidiary buds dimorphic or trimorphic and culm leaves also deciduous ( Clark 1989, Clark 1992, Fisher et al. 2009). Another species belonging to this informal group is C. juergensii , which also appears as sister to C. mimosa subsp. australis + C. nudiramea , but with no support. This evidence suggests that the informal group C. nudiramea may be monophyletic, although it is necessary to analyze the species of this group with more markers and including more samples of Brazilian species of Chusquea .

The Chusquea meyeriana informal group comprises five species: C. anelythra Nees (1835: 491) , C. anelytroides Ruprecht ex Döll (1880: 206) , C. attenuata ( Döll 1880: 170) Clark (1993: 237) , C. longispiculata , and C. meyeriana . It is characterized by infravaginal branching, extremely reduced glumes I and II and reflexed lower inflorescence branches, with one or more spatheate bracts subtending the inflorescence ( Fisher et al. 2009, 2014). All taxa sampled of this informal group, except C. longispiculata , were recovered in clade VI, lineage A ( Fig. 4 ), which also includes several individuals that were morphologically similar to these species but were difficult to accurately identify because some species concepts in this group remain to be clarified. The new species here described as C. gouveiensis also emerged within this clade, even though it does not share all of the morphological characters listed above. It differs from these species in having both infra-and extravaginal branching and in lacking subtending spatheate bracts and reflexed inflorescence branches.

The position of Chusquea gracilis within clade VI is uncertain. However, this species is clearly phylogenetically divergent from C. gouveiensis ( Fig. 4 ), despite their strong morphological similarities. Sequence data for all three markers were obtained for both species, so their differing positions are not due to missing data, confirming the recognition of C. gouveiensis as a new species from Brazil. Therefore, additional studies are needed to resolve the polytomies within this clade and to understand the phylogenetic relationships among C. gouveiensis , C. gracilis , and the other species of clade VI, as well as in other lineages of Chusquea which remain doubtful.

Figures

FIGURE 1. Chusquea gouveiensis. A. Culm leaf, showing the band of trichomes at the base. B. Node and central bud, highlighting the pilose band below the nodal line. C. Bud complement. D. Branching and foliage leaves. E. Flowering branches, showing synflorescence branching. F. Detail of the synflorescence, showing the weakly paniculate pattern of ramification. G. Spikelet. H. Glume III. I. Glume IV. J. Anthecium, palea view. K. Anthecium, lemma view (based on Vidal et al. 213).

FIGURE 2. Chusquea gouveiensis. A–B. Scandent habit. C. Infravaginal branching. D. Extravaginal branching. E. Fertile branches, synflorescences. F. Vegetative branches, ascending, and pilose band below the nodal line (Photos by K.V.A Vidal).

FIGURE 3. Geographic distributions of Chusquea gouveiensis and C. gracilis in Brazil.

FIGURE 4. Bayesian phylogeny of Chusquea based on combined nuclear (ITS) and plastid (3’ portion of ndhF and trnD-trnT) DNA sequences. BI PP ≥ 0.90 / ML bootstrap support ≥ 50% are shown above branches, and MP bootstrap support ≥ 50% is shown below branches. Symbols before the species names indicate the distribution of the taxa, according to the map presented. Symbols after the names indicate the subgenera to which the species belong. Clade VI, including C. gouveiensis (in bold), is highlighted in blue. Map from Fisher et al. (2014, Fig. 3).