New Record of Rhizomatophora aegopodioides Discovered in Southern Italy

A significant botanical discovery has expanded the known range of *Rhizomatophora aegopodioides*, a species belonging to the Apiaceae family, with its first confirmed record in Italy. This species, which is currently documented across the Balkan Peninsula, Greece, southern Caucasus, Turkey, and southern Russia, was identified during field surveys conducted in Calabria, southern Italy, in September 2016. The discovery was made in two distinct locations: the Argentino River Valley, specifically in Orsomarso, and along the Abatemarco River near Santa Maria del Cedro, both within the Cosenza area. These sites are geographically significant as they are located within or adjacent to the Pollino National Park, specifically within the Site of Community Importance known as the “Valle del Fiume Argentino.” The identification of this plant was made after careful surveys of relevant literature, including floristic and phytosociological studies of Southern Italy and Calabria, as well as detailed morphological comparisons against established descriptions and analytical keys from various historical and modern botanists.

The purpose of this research was multifaceted: to verify the correct identification of this disjunct population appearing in southern Italy and to differentiate it from related genera that are already documented in the Italian vascular flora. Furthermore, the study aimed to increase the overall knowledge base concerning the Italian vascular flora by providing comprehensive taxonomic, phytosociological, and distribution data relating to this newly recorded finding. The genus *Rhizomatophora*, which is monotypic and characterized by perennial plants, is noted for its preference for hygrophilous forests, alder forests, riverbanks, wetlands, and freshwater habitats. This specific species, *R. aegopodioides*, is distributed in a wide range of regions, and its presence in Calabria marks the westernmost stand of its known distribution range within the Italian peninsula, while also representing the lowest altitude recorded for the species in this country.

Field investigations were meticulously carried out in September 2016 in Calabria, focusing on the Argentino River Valley and the Abatemarco River. Ten samples were collected during these excursions. For conservation purposes, one individual specimen was transplanted to the “Carmela Cortini” Botanical Garden of the University of Camerino for ex situ preservation. The Argentino River Valley locality, for instance, falls within the Site of Community Importance “Valle del Fiume Argentino,” and the collection sites were characterized by calcareous substrata and surrounding wetlands. The species exhibits a specific distribution pattern in Calabria, being widespread along the banks of both the Abatemarco and Argentino rivers, highlighting its preference for riparian and wetland environments.

Morphological analysis of the Calabrian material provided detailed characteristics distinguishing *Rhizomatophora aegopodioides* from closely related genera such as *Peucedanum* and *Cervaria* within the Italian flora. The plants are described as erect perennials, reaching heights of 70 to 120 centimeters, and they possess long horizontal rhizomes. The stems are solitary, glabrous, and fistulous, while the leaves are large, typically 2–3 ternatisect, and feature broadly triangular laminae with oblong lobes. The petioles are striated when viewed in cross-section and are hollow. The umbels are notable for having 20 to 35 unequal, slender, minutely scabrous rays, which are predominantly located on one side of the structure. The flowers feature white petals that are largely ovate, with an erect apex that is slightly emarginated, and the lobes are swollen. The mericarps are described as glabrous, measuring 5 by 6.5–7 millimeters, and are broadly elliptical or almost round, dorsally compressed, and possess broad wings measuring 1.5 to 2 millimeters.

The taxonomic classification of *Rhizomatophora aegopodioides* places it within the order Apiales and the family Apiaceae. The species has been cited under several synonyms throughout its history, including *Physospermum aegopodioides* Boiss., *Peucedanum aegopodioides* (Boiss.) Vandas, and *Cervaria aegopodioides* (Boiss.) Pimenov. The genus *Rhizomatophora* itself is characterized by several unique morphological traits that differentiate it from related taxa. These include the presence of long horizontal rhizomes, fistulous petioles and stems, leaves that are 2–3 ternatisect, and the presence of largely triangular teeth on the calyx. Furthermore, the genus is distinguished by its widely winged mericarps with light striations and continuous secretory canals, features that are not present in *Cervaria* s.str. or *Peucedanum* s.str. The detailed morphological comparison, as summarized in Table 2, confirms the distinct characteristics of the Calabrian population.

Ecologically, *Rhizomatophora aegopodioides* is associated with specific forest types and habitats. In the Italian context, it is found growing in hygrophilous forests, alder forests, riverbanks, and freshwater habitats, generally at altitudes ranging from approximately 100 to 200 meters above sea level. A relevé conducted at the Santa Maria Del Cedro locality on September 25, 2016, at an altitude of 127 meters, documented the presence of *R. aegopodioides* alongside several other species, including *Alnus glutinosa*, *Populus nigra* subsp. *nigra*, *Carex pendula*, *Solanum dulcamara*, and various other associated flora. This detailed relevé provides insight into the community structure of the habitat where the species thrives.

The phenological cycle of *Rhizomatophora aegopodioides* is well-documented, with the species typically flowering during the months of August and September, and subsequently fruiting between September and October. The chromosome number for this species has been determined to be 2n = 22, based on material examined from Bulgaria and Greece, suggesting a consistent genetic profile across its known range. The study of this species contributes to the understanding of the distribution of plants with an eastern range within the Italian flora, which is considered one of the richest in Europe. The discovery of *R. aegopodioides* further underscores the importance of floristic and taxonomic research for conservation efforts, especially given the species’ presence in sensitive areas like the Pollino National Park.

Given that this is a new record for Italy, further field surveys are considered indispensable. These future surveys are necessary to accurately define the effective distribution area and to fully understand the ecological requirements and the origin of these disjointed populations of *R. aegopodioides* within the Italian peninsula. Additionally, monitoring the species is deemed crucial to assess the conservation status of the population found in Calabria. The current finding represents a vital addition to the knowledge of the Italian vascular flora, highlighting the need for continued research into the distribution of species with eastern origins in this region.

Subject of Research: Discovery and taxonomic description of Rhizomatophora aegopodioides in Southern Italy

Article Title: First record of Rhizomatophora aegopodioides ( Apiaceae ) in Italy

Article References: Pennesi, R., Cunto, E., & Ballelli, S. (2023). First record of Rhizomatophora aegopodioides (Apiaceae) in Italy. Italian Botanist, 15, 65-76. https://doi.org/10.3897/italianbotanist.15.98538

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.15.98538

Keywords: Apiaceae, Rhizomatophora aegopodioides, Calabria, Botanical Discovery, Vascular Flora, Taxonomy, Ecology, Pollino National Park, First, record, Rhizomatophora, aegopodioides