Geranium lucarinii Venanzoni & Wagens., 2021

Wagensommer, Robert Philipp & Venanzoni, Roberto, 2021, Geranium lucarinii sp. nov. and re-evaluation of G. kikianum (Geraniaceae), Phytotaxa 489 (3), pp. 252-262 : 253-258

Geranium lucarinii Venanzoni & Wagens. , sp. nov. Figs. 2–3 .

Species Geranio macrorrhizo similis sed dentibus calycinis 3.0– 4.2 mm longis et foliis semper perpetuo virentibus, in segmentorum margine saepe imbricatis.

Types: — ITALY. Umbria: Terni, nei pressi della Cascata delle Marmore, parete di roccia calcarea, 42°33’N, 12°42’E, 200 m, 07 June 2019, R . Venanzoni et R.P. Wagensommer s.n. (holotype CAME!, isotypes: FI! and BI!) .

Paratypes: — ITALY. Umbria: Ad rupes secus La Caduta delle Marmore , June 1832, E . Fiorini-Mazzanti s.n. (sub G. macrorrhizum L.) ( RO [digital image!]); Alle rupi della Caduta delle Marmore , June 1834, P . Sanguinetti s.n. (sub G. macrorrhizum L.) ( RO [digital image!]); Terni sopra Papigno, June 1834, P . Sanguinetti s.n. (sub G. macrorrhizum L.) ( RO [digital image!]); Terni, nei pressi della Cascata delle Marmore , parete di roccia calcarea, 42°33’N, 12°42’E, 200 m, 18 May 2016, R . Venanzoni s.n. (sub G. macrorrhizum L.) ( PERU!).

Herb perennial. Rootstock 6.2–11.8 mm in diameter. Stem 21–35 cm tall, erect, with abundant eglandular hairs 0.1–0.3 mm long, rare eglandular hairs 1.5 mm long and patent, glandular hairs 0.2–1.2 mm long. Basal leaves in persistent rosette, polygonal in outline, palmatifid, (5.1–)6.2–12 × 4.3–7.5 cm, velvety, with eglandular hairs and glandular hairs on adaxial and abaxial surface; segments 5, often overlapping on the margin; middle segment rhombic, 9.6–16.3(–19.2) mm wide at base, 13–27-lobed in distal half. Petiole up to 23 cm long, with eglandular hairs 0.1–0.2 mm long, very rare eglandular hairs 1.5 mm long and patent, glandular hairs 0.2–1.2 mm long. Cauline leaves 2, opposite, smaller than basal leaves. Inflorescence a dichasial cyme; peduncles (20–)40–75(–90) mm long, with eglandular hairs 0.2–0.3 mm long and glandular hairs 0.3–1.3 mm long; pedicels 7–18 mm long, with eglandular hairs 0.1–0.3 mm long and glandular hairs 0.3–0.8 mm long. Sepals 5, 11– 12.5 mm long (8–9 mm plus a mucro 3–4.2 mm long), with eglandular hairs 0.1–0.3 mm long, rare eglandular hairs 1.5 mm long, and patent, glandular hairs 0.2–1.2 mm long. Petals 5, free, entire, pink, whitish veined, with limb patent-spreading, 7.2–10.2 mm wide, and claw 2.3–3 × 5.5–7.2 mm. Stamens 10, long-exserted, with filaments 19–22 mm long, reddish-pink, and anther ca 2 mm long, purple. Gynoecium 20–35 mm long; ovary 5-locular; style 17–32 mm, pink, exceeding stamens; stigmas 5. Fruit splitting into 5 one-seeded mericarps.

Distribution and Habitat:— Geranium lucarinii is a very rare and localized species collected in central Italy, where a small population was observed near Marmore waterfalls, in Umbria Region. Currently it is known only from the locus classicus. It grows on a near vertical calcareous rocky wall (“Calcare massiccio” of the Umbria-Marche geological sequence) with north-west exposure, at an elevation range of 190–250 m a.s.l. The bioclimate is Temperate var. submediterranean ( Venanzoni et al. 1998) . The vegetation context is a termo-xerophilous/mesomediterranean sclerophyllous rocky open wood of Quercus ilex L., attributed to the association Cyclamino hederifolii-Quercetum ilicis Biondi et al. ex Biondi, Casavecchia & Gigante in Biondi et al. 2013 ( Biondi et al. 2003). Most common species observed are Arabis alpina L. subsp. caucasica (Willd.) Briq. , Asplenium trichomanes L., Cephalaria leucantha (L.) Roem. & Schult., Cymbalaria muralis G.Gaertn., B.Mey. & Scherb. , Euphorbia characias L., Fraxinus ornus L., Galium corrudifolium Vill. , Hedera helix L., Helichrysum italicum (Roth) G.Don , Hieracium racemosum Waldst. & Kit. ex Willd. subsp. crinitum (Sm.) Rouy , Micromeria graeca (L.) Benth. ex Rchb., Oloptum thomasii (Duby) Banfi & Galasso , Osyris alba L., Parietaria judaica L., Phillyrea media L., Pistacia terebinthus L., Quercus ilex , Rhamnus alaternus L., Smilax aspera L., Teucrium flavum L., Vincetoxicum hirundinaria Medik. , etc. This floristic context, together with the fact that the Marmore station is heavily de-alpinized, is to be reported as characteristic habitat of G. lucarinii ; in fact, in Italy, almost all the Apennine and Peninsular stations of the similar species G. macrorrhizum are located in a mountain/high mountain context range over 1000 m a.s.l. with vegetation referable to beech woods.

Eponymy:— The specific epithet refers to Domenico Lucarini (Camerino 1954-2017), Curator of the Herbarium CAME at the University of Camerino and responsible for the taxonomic checklist within the project www.anArchive. it ( Lucarini et al. 2015).

Phenology: —Flowering (March–)April to May(–June), rarely fruiting.

Conservation status: —According to the field investigation, the new species has a very restricted almost punctiform distribution. In addition, the only known population is represented by a limited number of individuals. The growing site of this plant is currently threatened by quarry work, a free climbing training polygon, and wall cleaning, which could lead to a significant decrease of the population size and of the habitat quality. Therefore, according to the IUCN (2019) criteria, the species must be included in the following category: Critically Endangered CR B1ab(i,ii,iii, iv,v)+2ab(i,ii,iii,iv,v).

As for other endemic taxa with a puntiform or very limited distribution reported in the Italian peninsula (e.g. Brullo et al. 2015, Perrino et al. 2018, Bernardo et al. 2020, Conti et al. 2020, Wagensommer et al. 2020), it will be necessary in the next future to define the appropriate strategies for the long-term conservation of the species.

Taxonomic remarks: —Morphologically, Geranium lucarinii is closely related to G. macrorrhizum in having in common a trait combination quite significant from the taxonomical point of view. In particular, both species are perennial, characterized by a thick rootstock, basal leaves in rosette, palmatifid, with 5 segments, middle segment rhombic, cauline leaves opposite, inflorescence a dichasial cyme, cymules usually 2-flowered, flowers slightly zygomorphic, petal claws and rostrum hairy, style glabrous or slightly hairy, stamens exserted, more than twice as long as sepals, etc.

Our investigation on dried and living material allowed to put in evidence some remarkable diacritic features ( Table 1). In fact, G. macrorrhizum is characterized by basal leaves persistent or deciduous, with segments rarely overlapping on the margin, peduncles (2.5–)13–32(–61) mm long, pedicels (2.5–)6.5–11.2(–15.4) mm long, sepal mucro (1.4–) 2–3.2 mm long, ratio of sepal mucro length to sepal length (0.22–)0.29–0.34(–0.40), whereas G. lucarinii shows always persistent basal leaves, with segments often overlapping on the margin, peduncles (20–)40–75(–90) mm long, pedicels 7–18 mm long, sepal mucro 3–4.2 mm long, ratio of sepal mucro length to sepal length 0.37–0.46.

The ecological behaviour and the flowering period of the new species also clearly differ from those of the other known taxa of Geranium sect. Unguiculata . In fact, G. lucarinii grows on calcareous rocky slopes, at 190–250 m a.s.l., in a Mediterranean vegetation context, as highlighted by the presence of Helichrysum italicum , Micromeria graeca , Oloptum thomasii , Pistacia terebinthus , Quercus ilex , Rhamnus alaternus , Smilax aspera , Teucrium flavum , etc, flowering from (March-)April to May (rarely June). On the contrary, G. dalmaticum grows in fissures, crevices and screes of limestone rocks, at 300–900 m a.s.l., and is at its best in the Pinus nigra J.F.Arnold zone, flowering from June to August ( Beck 1896, Rechinger 1934, Yeo 2004, Aedo 2017a), whereas G. macrorrhizum occurs in rocky places including loose material, open forests and meadows, on limestones, serpentines, or siliceous soils, at 50–2800 m a.s.l., flowering from April to September ( Aedo 2017a), behaving as an orophilous species in the Mediterranean area ( Pignatti 1982, Tan et al. 2011). In central Italy, in particular, G. macrorrhizum usually grows in orophilic screes ( Conti & Manzi 1993), sometimes in the mountain belt on calcareous rocks and also in beech forests. In southern Italy, G. macrorrhizum is reported from Campania at very low altitudes ( Del Guacchio 2002, Salerno 2004). Those last populations are under investigation to verify their correct attribution to G. macrorrhizum or to G. lucarinii (Ceccarelli et al., in prep.).

Inside Geranium sect. Unguiculata, Tan et al. (2011) described G. kikianum from Peloponnese, Greece, distinguished by its smaller and narrower (5.5–7.0 mm broad) deflexed petal limb, slender claw (less than 1 mm wide at the broadest part near the limb) and occurrence in wet habitats. Aedo (2017a) considered G. kikianum as a synonym of G. macrorrhizum . Nevertheless, for the comparison of the two taxa, he erroneously refers to the petal length (that does not show significant differences between the two species), while Tan et al. (2011) referred to the width of petal limb and claw. In our opinion, Tan et al. (2011) highlighted relevant morphological differences to distinguish the population from Mt Taigetos, that was correctly considered as a different species. As a consequence, G. macrorrhizum does not occur in Peloponnese.

Also the ecology and phenology of G. kikianum clearly differ from those of G. lucarinii , as G. kikianum occurs at 1400–1450 m a.s.l. in wet places, together with Aremonia agrimonoides (L.) DC., Geranium asphodeloides Burm. f., G. versicolor L., Primula vulgaris Huds. , Veronica anagallis-aquatica L., etc., flowering from late May to June ( Tan et al. 2011).

Figures

FIGURE 2. Geranium lucarinii in the locus classicus (Photo by R. Venanzoni).

FIGURE 3. Holotype of Geranium lucarinii (preserved at CAME).