Senecio reitzianus Cabrera 1957
Creators: name: Funez, Luís Adriano
name: Hassemer, Gustavo
name: Ferreira, João Paulo Ramos
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Senecio
Senecio reitzianus

description: Senecio reitzianus Cabrera (1957: 241)   
 Type: — BRAZIL. SANTA CATARINA: Florianópolis, dunas da Lagoa, 6 November 1946, J.A. Rohr 609 (holotype LIL 203929, barcode LIL001606!). Figs. 1–2.   
 Additional material examined: — BRAZIL. SANTA CATARINA: Florianópolis: Costão do Santinho, 27°28’16.11” S, 48°22’30.24” W, 28 November 2015, L.A. Funez 4611 (FURB 50034).   
 Description: —Perennial herbs 15–35 cm tall. Stems prostrate, radicant, ascending toward apex, glabrous or with a very scarsely arachnoid indument on axils of apical leaves, densely foliose apically. Leaves gradually decrease apically, sessile, blades oblong-spathulate, 23–53 × 2–13 mm, apex acute or obtuse, attenuate toward base, slightly auriculate, penninervate, secondary veins abaxially reticulate, coriaceous to slightly succulent, glabrous on both sides, except for few arachnoid trichomes in axils of apical leaves, margin slightly revolute, entire or with (2)–3–5 teeth apically. Capitulescence terminal with 2–12 capitula disposed in a lax corymb with glabrous axes. Capitula heterogamous, radiate, pedunculate; peduncles 1.3–4 cm long, bracteolate, glabrous; bracteoles 1–5, lanceolate to linear-lanceolate, 1.5–7 mm long, glabrous or with very sparse arachnoid trichomes. Involucre cupuliform, 7–11 × 8–10 mm, calyculate; bracts of calycule ca. 10, lanceolate, 3–4 mm long; involucral bracts ca. 20, lanceolate, 6.1–10.0 × 1.0– 1.2 mm wide, with apex acute and margin entire, glabrescent abaxially with arachnoid trichomes between involucre and calycule; receptacle plane and glabrous. Ligules 5–13, pistillate, yellow, tube 3.0– 3.5 mm long, limb 2–5-dentate, 6–8 mm long; disk florets ca. 60–80, perfect, corolla yellow, tubulose, tube 4.0– 5.5 mm long, limb 3.1–4.0 mm long. with five triangular lobes up to 0.5 mm long; anthers 1.5–1.7 mm long, connectival appendage oblong, 0.5–0.6 mm long; style 3.0– 3.5 mm long, style branches 1.2–1.3 mm long. Cypselae cylindrical, 3.0–3.2 × 1.0 mm, 10-costate, glabrous, carpopodium symmetrical, setose; pappus 7–9 mm long, uniseriate, bristles white, filiform, deciduous.   
 Distribution: —Endemic to a very narrow area of ca. 0.5 km ². Currently it survived in the only locality known as “Costão do Santinho”, in Santa Catarina Island, southern Brazil, ca. 20 km from the type locality (Fig. 3).   
 Habitat: —Humid rocky shores, from the sea spray zone to the herbaceous vegetation less than 1 m tall (Fig. 4). Conservation status: —Critically Endangered (CR–B2a,b[iii]). This species has an area of occupancy (AoO) of only 0.5 km ². Senecio reitzianus was preliminarily assessed as Endangered (EN) in Hassemer et al. (2015) based on the known distribution, but no information on its population was available then.   
 Comments and discussion: —Although the population occupies a very restricted area, there are more than a hundred of mature individuals in the contour of ca. 500 m ², forming small clusters along seaside rocks. We were unable to find any other population, despite thorough search in nearby areas and in ecologically similar areas on Santa Catarina Island. This population is located within a protected area, the Reserva Particular de Patrimônio Natural Morro das Aranhas, which offers a certain degree of protection to this species.   
 Senecio reitzianus was described from the sand dunes of Lagoa da Conceição. This area, as the entire Santa Catarina Island, can be considered well-sampled and botanically well-known (Falkenberg 1999, Hassemer et al. 2015). The sand dunes of Lagoa da Conceição are particularly well sampled and studied, with at least three works treating its flora and vegetation, i.e. Bresolin (1979), Falkenberg (1999) and Guimarães (2006). Therefore, we presume that the type population of this species is no longer extant.   
 There are other species of Senecio that may occur sympatrically with S. reitzianus, e.g. S. crassiflorus (Poiret 1811: 267) Candolle (1838: 412), which inhabits similar litoral environments and can be confused with S. reitzianus due to its ascendant stem, radicant in the lower nodes, oblanceolate-spatulate leaves that are entire or somewhat crenate, and capitulum with yellow ligulate flowers. However, both species can be readily differentiated. While S. reitzianus is characterised by glabrous stems, with glabrous involucre bracts 8–10 mm long (Cabrera 1957, Cabrera & Klein 1975), S. crassiflorus has albo-tomentose stems, with densely tomentose involucre bracts 14–17 mm long (Cabrera 1957, 1974, Cabrera & Klein 1975, Matzenbacher 1998). Further characters to differentiate these species can be found in the identification key provided here.   
 Senecio reitzianus is quite similar to S. oligophyllus Baker (1884: 317), from which it differs by ascending stems 20–30 cm in S. reitzianus vs. erect stems up to 100 cm in S. oligophyllus. The leaves in S. reitzianus are coriaceous to succulent, oblong-spathulate with the apex obtuse vs. leaves papyraceous, lanceolate with the apex acute in S. oligophyllus.   
 Senecio reitzianus was previously only collected by Rohr, who assigned “dunas da Lagoa ” as the collection site, an area which comprises a total of 500 ha (Guimarães 2006). Without a clear description of the collection site, Cabrera (1957) and Cabrera & Klein (1975) believed that the species occurred in sand soils (dunes) since they used terms like “possible” and “probable” when attributing a site description to S. reitzianus in both works.   
 It is intriguing how the type of S. reitzianus was kept at LIL herbarium (which is located in Tucumán, northwestern Argentina) since there was no real connection between the collector (J.A. Rohr) and the species authority (Á.L. Cabrera). It is also interesting why Cabrera named the new species in honour of Brazilian botanist (and also priest) Raulino Reitz (1919–1990) instead of the collector (Rohr). A feasible explanation is that Rohr and Reitz were aware of each other’s works through mutual correspondence letters, as shown by Pabst (1951), since both lived in Santa Catarina during the 1950’s and worked on the conservation of orchids. Both priests were naturalists, highly concerned about the future of the institutions and preservation of the natural resources in SC, as evidenced by their creation of museums, herbaria and biological reserves (Guerra 2010). Since Rohr started to dedicate most of his time on archaeological excavations during the 1950’s (Schmitz 2009, Reis & Fossari 2009, Comerlato 2014), we consider it probable that the type of S. reitzianus was sent to Reitz by Rohr. Afterwards, Reitz, knowing that Cabrera was already a reputed specialist in Asteraceae in austral South America (Crisci 1998), decided to send him the type of S. reitzianus. This is probably the reason why Reitz and not the collector of the type (Rohr) was honoured with the specific epithet of the species.
description: Published as part of Funez, Luís Adriano, Hassemer, Gustavo & Ferreira, João Paulo Ramos, 2017, Rediscovery of Senecio reitzianus (Asteraceae), a species believed to be possibly extinct, on Santa Catarina Island, southern Brazil, pp. 183-191 in Phytotaxa 291 (3) on pages 184-188, DOI: 10.11646/phytotaxa.291.3.2, http://zenodo.org/record/13699456