Calea spiralis V.R.Bueno, Gostel & G.Heiden, 2023

Bueno, Vinicius R., Gostel, Morgan R. & Heiden, Gustavo, 2023, The spiraling story of Tyleropappus and a new name for Calea (Asteraceae: Neurolaeneae) from Venezuela, Phytotaxa 622 (1), pp. 75-84 : 77-80

Calea spiralis V.R.Bueno, Gostel & G.Heiden , nom. nov.

≡ Tyleropappus dichotomus Greenman in Gleason (1931: 386–387). Type:— VENEZUELA. Amazonas: Atabapo, Parque Nacional Duida-Marahuaka , Cerro Duida , [“Summit of Peak 7, 7100 ft., 605 ”], summit of peak 2,164 m, August 1928 to April 1929, G.H.H. Tate 605 (NY [NY274310]!, lectotype designated here; isolectotype US [ US 00124570]!). ( Fig.1 )

Shrubs, 0.4–1 m tall; stems cylindrical, smooth, strigose to pubescent, castaneous, internodes 0.13–0.45 mm long. Leaf arrangement spiral, alternate, sessile or petiolate, 0.6–1 mm long; blades 0.5–2 × 0.1–0.25 cm, linear to narrow elliptic, base attenuate, apex acute, venation hiphodromous, margins entire, revolute, abaxial surface glandular-punctate to sparsely glandular-punctate, adaxial surface glabrous; chartaceous, discolorous, dark green in abaxial side, olivaceous in adaxial side. Capitula solitary or arranged in lax dichasial cymes, secondary capitulescence axes 2 (when present), terminal; sessile or with short peduncle 0.2–1.5 mm long, strigose to puberulous, eglandular. Capitulum homogamous, discoid; involucre 5.5–7.5 × 5–6.85 mm, longer than wide, cylindrical. Phyllaries 3–4-seriate, conspicuously striate, margins entire; first series of phyllaries 5.7–9.5 × 0.9–2 mm, narrow elliptic, apex acute, margins revolute, sparsely glandular-punctate, 1–3-striate; innermost series margins flat, glabrous, pale yellow, scarious; second series 5.3–6.3 × 1.3–3.4 mm, oblong, obtuse or rounded, 8–10-striate; third series 6.4–8 × 2.7–3 mm, oblong, obtuse or rounded, 6–10 striate; fourth series 6.8 × 1.8 mm, oblong, rounded, 6–10 striate; receptacle conical, epaleaceous. Ray florets absent. Disc florets 8–12, bisexual, corolla 4–7.2 mm long, tubular, tube 1.35–3 mm long, lobes 1–1.5 mm long, densely glandular-punctate to sparsely glandular-punctate, yellow; anthers 1.8–2 mm long, light yellow, apical anther appendages ovate; style arms 0.5–1 mm long, yellow, linear. Cypselae 2.25–3 mm long, prismatic or obconic, 4- angled, sparsely hirsute to hirsute, ribs densely hirsute, black; pappus bitypic, bilength, scales 13–20 (7–8 distinctly longer) or polylength, free, uniseriate, shorter scales 1.3–4 mm long, medium scales 3–3.7 mm long (only present when polylength), longer scales 3.4–4.7 mm long, linear, apex acute or long acuminate, margins entire, erose.

Distribution and Habitat:— Calea spiralis is a stenoendemic occurring exclusively in Cerro Duida, a tepui in the Amazonas Department, Venezuela ( Fig. 2 ). It grows in savannas on hilly areas at the table mountain summit of the Cerro Duida, which has a summit area of 1,089 km ² ( Huber 1997). Gleason (1931) indicated that C. spiralis is found at elevations around 2,164 m ( Gleason 1931). However, Rull & Vegas-Villarrúbia (2006) suggested that the elevation range of this species is between 2,200 and 2,358 m above sea level, based on the lowest and highest tepui summit area.

Informal Conservation Assessment:— Calea spiralis was only found in Cerro Duida, which is inserted in DuidaMarahuaca National Park. Despite this protection, the species is threatened with habitat loss by upward displacement, because of the projected global warming (Vegas-Vilarrubia et al. 2012) for the end of this century. Calea spiralis was collected only once, even though other field work have been later realized to Cerro Duida by Julian A. Steyermark in 1944 and by Bassett Maguire in 1949 and 1950 ( Huber 1997). This is an indication that possibly this species does not have significant populations in the locality or has few populations in general. So, in order to follow the IUCN Guidelines (2022), we consider that the total Extent of Occurrence of this species is the summit area of the Cerro Duida: 1,089 km ². As a result, criterion B1 ( IUCN 2022) is the only one that can be rigorously applied, since unfortunately the species was collected only once. Therefore, condition A of criterion B could be applied, but more expeditions to Cerro Duida are needed to corroborate this assumption. Considering all the information presented here, we conclude that C. spiralis is Endangered (B1).

Etymology:—Direct transfer for T. dichotomus with the same epithet in Calea is not possible, since the name C. dichotoma , a synonym of C. ternifolia , has already been occupied. Therefore, the new epithet “ spiralis ” is provided to refer to the spiral, alternate arrangement of leaves in Calea spiralis , a distinctive and unique morphological trait in the genus.

Phenology:—The specimens were collected with florets and fruits between August of 1928 and April of 1929, when the collector G.H.H. Tate was in the Cerro Duida ( Tate & Hitchcock 1930). According to Aristeguieta (1964), the correct date is April 1929, therefore this date is adopted here.

Taxonomic comments:—As two syntypes of Tyleropappus dichotomus were cited in the protologue and have fertile material, the specimen from NY is selected as the lectotype because G.H.H. Tate worked there during his lifetime in New York ( Smith 2005). Greenman, the author of Tyleropappus , worked at the Missouri Botanical Garden for a long time, but no syntypes were found there during a visit by the lead author of this work in 2022.

The striate phyllaries, disc florets, cypselae, and arrangement of pappus scales in C. spiralis are distinctive morphological characteristics that support the placement of Tyleropappus in Calea . The first series of phyllaries longer than both involucre and the second series of phyllaries, combined with the presence of (often) solitary capitula, are unusual features in Calea found in the Nana clade ( Fig. 3 ) according to Bueno (2023). This clade contains four other species, including C. coridifolia Pruski (2011: 1–3) , C. linearifolia Maguire & Wurdack (1957: 371) , C. nana Maguire ( Maguire et al. 1953: 147) , and C. saxatilis Cuatrecasas (1954: 236) . These species share herbaceous to shrubby habit, narrow leaves (up to 1.6 mm wide), absence of eglandular trichomes on vegetative organs, short peduncles, 3–4 seriate involucre, outermost phyllaries larger than or equal to the second series of phyllaries and involucre, and pappus scales longer than the cypselae. Species in the Nana clade occur predominantly in the Venezuelan Guayana region ( Huber 1997), with one disjunct species ( C. saxatilis ) in northern Colombia along the eastern Andean Mountains.

Calea spiralis is morphologically similar to C. linearifolia , which also has leaves up to 0.25 mm wide, a glandular-punctate abaxial surface, discoid capitula, cylindrical involucre, and fewer than 10 disc florets. Calea spiralis can be distinguished from the latter by the arrangement of leaves spiral, alternate (vs. decussate in C. linearifolia ), involucres 5–6.7 mm wide (vs. 2.5–3 mm), the second series of phyllaries scarious (vs. foliaceous), receptacle epaleaceous (vs. oligopaleaceous), corollas of disc florets glandular-punctate (vs. glabrous), cypselae with hirsute ribs and intercostal surfaces (vs. glabrous).

Calea spiralis and C. hymenolepis are the only two alternate leaves species of Calea . They can be distinguished by the spiral, alternate arrangement of leaves (vs. distichous alternate in C. hymenolepis ), involucre 3–4-seriate (vs. 5-seriate), phyllaries greenish yellow to yellow (vs. reddish yellow), second series of phyllaries 5.35–6.3 mm long (vs. 1.8–2.1 mm long), disc floret corolla lobes 1–1.5 mm long (vs. 1.7–2.6 mm long), cypselae 2.25–3 mm long (vs. 4.7–4.9 mm long) with hirsute (vs. glabrous) ribs and intercostal surface, and pappus scales 1.3–4.7 mm long (vs. 0.1–0.2 mm long).

Calea abelioides Blake in Gleason (1931: 488–489) was found in the ridge crests of the Monte Duida ( Gleason 1931), these two species are the only two species of Calea collected in this area. Calea spiralis and C. abelioides can be distinguished by the spirally alternate leaves in C. spiralis (vs. decussate in C. abelioides ), leaf blade 0.1–0.25 mm long (vs. 0.5–1.7 mm long), linear to narrow elliptic (vs. ovate), base attenuate (vs. rounded); capitulescence lax dichasiform cymose or capitula solitary (vs. umbelliform cymose), peduncle 0.1–0.2 cm long (vs. 2–7.6 cm long), involucre 3–4-seriate (vs. 5-seriate), epaleaceous receptacle (vs. hemipaleaceous) and pappus scales 13–20 (vs. 22– 25).

Additional Material Examined:— Calea abelioides : VENEZUELA. Amazonas : Atabapo, Parque Nacional Duida-Marahuaka, Cerro Duida , August 1928 to April 1929, G.H.H. Tate 768 ( US). Calea hymenolepis : BRAZIL. Goiás: Mineiros , 08 February 2021, J.M. Mendoza 4711 (ICN). Calea linearifolia : VENEZUELA. Amazonas : Serrania Paru, Caño Asisa , 2 February 1951, R.S. Cowan & J.J. Wurdack 31178 ( US). Calea saxatilis : COLOMBIA. Norte de Santander : Del Sarare , 23 November 1941, J. Cuatrecasas 13429 ( US) .

Figures

FIGURE 1. Calea spiralis nom. nov.(Neurolaeneae,Asteraceae).A. Flowering branch. B. Leaf abaxial surface. C. Indumentum of abaxial leaf surface. D. Capitulum. E. First series of phyllaries. F. Second series of phyllaries. G. Third series of phyllaries. H. Fourth series of phyllaries. I. Disc floret with bilength pappus scales. J. Cypsela with polylength pappus scales. A–J drawn from the lectotype H.H. Tate 605 (NY); A–J: millimeter scale. Illustration by Débora Dalzotto.

FIGURE 2. Distribution of Calea spiralis nom. nov. (Neurolaeneae, Asteraceae) in Venezuela. VE – Venezuela, BR – Brazil, CO – Colombia.

FIGURE 3. Schematic phylogeny of Calea (Neurolaeneae, Asteraceae) by Bueno (2023). The bold clade within the dashed box indicates the phylogenetic position of the Nana clade.