Senecio littoralis, , Scopoli, 1771

Calvo, Joel & Sennikov, Alexander N., 2018, On the neglected Scopoli’s name Senecio littoralis (Compositae) and its nomenclatural implications, Phytotaxa 357 (3), pp. 207-218 : 207-218

Senecio littoralis , a heterotypic synonym of Dittrichia viscosa

Scopoli characterized S. littoralis as a plant 2 feet (ca. 0.6 m) tall with sessile, lanceolate, dentate, viscid leaves, a racemose synflorescence composed of pedicels with a single capitulum arising from the leaf axils, glabrous involucres, and achenes bearing a pappus. The involucral bracts were described as fleshy and purple-coloured at the apex, and each capitulum as displaying 15–20 short ligulate florets (“diametro disci breviores”) and ca. four disc florets, both yellow. After the description, Scopoli compared the new species with S. viscosus Linnaeus (1753: 868) , assuming their similarity. He stressed the racemose synflorescence, the non-pinnatifid leaves, and the non-malodorous fragance of S. littoralis as the most important characters to separate the latter from S. viscosus .

Among the Mediterranean Senecio species and similar taxa with viscid indumentum, there are no species displaying a racemose synflorescence composed of single capitula on pedicels arising from the leaf axils. This character is very characteristic of the most common Dittrichia species thriving along the northern Adriatic coast, i.e., D. viscosa . Dittrichia is currently treated within Inuleae ( Anderberg 2009), far from the current concept of Senecio s.l., but on the next page of the same book Scopoli introduced another member of Inuleae as a species of Senecio , S. crithmifolius Scopoli (1771: 163) , nom. illeg. superfl. based on Inula crithmifolia Linnaeus (1759: 1219) , nom. illeg. superfl. ≡ Limbarda crithmoides ( Linnaeus 1753: 883) Dumortier (1827: 68) . This inclusion indicates that Scopoli’s generic concept was very broad.

Comparing the original concepts of Senecio littoralis and Erigeron viscosus (basionym of D. viscosa ), we noted that the two first polynomial names included by Linnaeus in the protologue of Erigeron viscosus stressed as a diagnostic character the single capitula on lateral pedicels(“pedunculis unifloris lateralibus”and “pedunculis simplicibus lateralibus unifloris longitudine folii, foliosis”), likewise Scopoli highlighted in the diagnosis of S. littoralis (“pedunculi uniflori, foliosi, ex alis foliorum”). At the same time it is odd that Scopoli, who was aware of Linnaeus’s work, did not adopt the name E. viscosus (or the respective polynomial name), a species that is quite common along the Istrian sea shore. In this line, it can be interpreted that Scopoli overlooked the Linnaeus species (perhaps because originally it was grossly misclassified in Erigeron , now Astereae ) and, for this reason, described it as new under the name S. littoralis .

At the end of the protologue of S. littoralis, Scopoli stressed the lack of malodorousness (“foetore nullo”) as a character to separate it from S. viscosus . It is important to note that this feature should be interpreted as a lack of bad smell instead of a lack of odor; the odorlessness in such viscid Mediterranean plants is not common. The species D. viscosa is indeed characterized to have a strong smell ( Bertoloni 1853 –1854, Font i Quer 1961, Santos et al. 2016), which is not unpleasant. In contrast, the whole plant of S. viscosus emits a disagreeable smell ( Wilkes 1828).

There are however some details in the description of S. littoralis that do not perfectly match the characters of D. viscosa . The involucre was described as glabrous with fleshy involucral bracts, which differs from the rather viscid and herbaceous involucre of D. viscosa . Scopoli also emphasized that the ray florets were short but those of D. viscosa are actually quite long, at least longer than the diameter of the involucre. This dissimilarity may be explained if the dried specimen used by Scopoli had faded ligules. Finally, he stated a striking low number of disc florets per capitulum (“ad 4”), which is unlikely among Mediterranean Compositae species with yellow radiate capitula. Senecio sylvaticus Linnaeus (1753: 868) , a somewhat viscid species with relatively small capitula thriving in Istria ( Kadereit 2014) has 18–55 disc florets, whereas S. viscosus has 45–70 disc florets. Despite these minor disagreements, the major characters provided by Scopoli lead us to follow Beck’s interpretation and to retain the name S. littoralis in the synonymy of D. viscosa .

Since the original material of S. littoralis is apparently lost, we designate herein a neotype in order to remove any uncertainty surrounding the application of this name. It is a collection from Portorož, a coastal village of northwestern Istria that currently belongs to Slovenia. At the time when Scopoli published his Flora Carniolica this village was still part of the Republic of Venice, but it was situated only ca. 20 km away from Trieste in the Austrian Empire and eventually became part of the Austrian Littoral in the 19 th century. The selected specimen (GZU 000235952, Fig. 1 ) contains two organisms displaying clearly dentate leaves and racemiform synflorescences, which match the information provided in the protologue of S. littoralis . A duplicate is kept at LJU.

Dittrichia viscosa (Linnaeus) Greuter in Greuter & Charpin (1973: 71). Erigeron viscosus Linnaeus (1753: 863) [ “viscosum ”]. Solidago viscosa (Linnaeus) Lamarck (1779: 144) . Inula viscosa (Linnaeus) Aiton (1789: 223) . Pulicaria viscosa (Linnaeus) Koch (1837: 361) . Cupularia viscosa (Linnaeus) Godron & Grenier (1850: 181) . Jacobaea viscosa (Linnaeus) Merino (1906: 336) . Type:—[Cultivated material from the garden of George Clifford III, Netherlands] Herb. Clifford 409 (lectotype, designated by Turland in Jarvis & Turland (1998: 360): BM 000647101, digital image!).

Senecio littoralis Scopoli (1771: 162) . Type :— SLOVENIA. Coastal-Karst : Istra , promontorii Seča prope oppidulum Portorož , 2 Oct 1981, M. Lovka & T. Wraber s.n. (neotype, designated here: GZU 000235952 , digital image!; isoneotype: LJU).

Figures

FIGURE 1. Neotype of the name Senecio littoralis (GZU 000235952). Copyright of the Herbarium GZU of the Karl-Franzens-University Graz.