Limonium ophioides Apostolopoulos & Constantinidis

Apostolopoulos, Efstathios & Constantinidis, Theophanis, 2024, Limonium ophioides and L. nichoriense (Plumbaginaceae), two new diploid species from Peloponnisos, Greece, Phytotaxa 655 (2), pp. 159-172 : 160-163

Limonium ophioides Apostolopoulos & Constantinidis sp. nov. ( Figs. 1 , 2 )

Type:― GREECE. Peloponnisos: Nomos Lakonias, Eparchia Epidavrou Limiras. The coastal area between Paleokastro and Tsoumala, south of Agios Prokopios church and c. 6 km linear distance south of Neapolis Voion town. The rocky parts of the coastline along a hiking trail and close to a dirt road. Alt. 2–5 m, 36°27′52′′N, 23°04′11′′E, 27 August 2023, E. Apostolopoulos & Th. Constantinidis no 669 (holotype ATHU!, isotypes B!, M!).

Description: —Plant perennial, glabrous, forming a sub-shrub 20–50 cm tall, with many erect, green stems and a robust taproot. Caudices robust, 2–5 cm long, branched, and covered by rosette leaves at apices. Leaves fleshy, green, glabrous, rugose, usually withered at anthesis, 20–50 mm long and 3–7.5 mm broad, narrowly spathulate, revolute at margin, retuse or rounded at apex, with one central nerve, lamina gradually tapering into petiole. Stems numerous, glabrous, robust, jointed, with many nodes of articulation, very flexuous, constricted and fragile at the nodes, smooth to rugose, very branched, with the first branching point at 1.5–5 cm above leaf rosette. Stem internodes thickened, 1–2 cm long. Sterile branches 8–12 per stem, curved, articulate, unbranched, 0.5–4 cm long, forming branching angles of 40°–60°. Fertile branches 2–4 per stem, confined to the upper third of the stem, articulate, usually unbranched, 2–7 cm long, slightly curved to straight, erect, forming branching angles of 30°–40°. Inflorescence narrowly obtrullate in outline. Spikes 20–40 mm long, straight to curved, mostly serpentine in shape. Spikelets fine, laterally slightly curved, 5–6 mm long, composed of 1–2 flowers, remotely arranged at 3 per cm. Outer bract 0.8–1.2 mm long and 1–1.2 mm broad, glabrous, triangular-ovate; bract margin narrowly membranous; central part fleshy, acuminate. Middle bract membranous, glabrous, 1.5–1.7 mm long and 1–1.1 mm broad, elliptic, obtuse. Inner bract 3–3.6 mm long and 2.1–2.3 mm broad, glabrous, rugose, elliptic, rounded, with a narrow membranous margin 0.2–0.4 mm wide; central part fleshy, forming a triangular tip 0.3–0.4 mm long, nearly reaching the upper margin. Calyx 4–4.5 mm long, exceeding the inner bract by 2.2–2.8 mm. Calyx tube densely hairy with short hairs at the base, glabrous beyond. Calyx ribs ending shortly above the base of lobes; calyx lobes ca. 0.5–0.7 mm long, semi-elliptic to acute. Corolla pale violet. Seeds 1.4–1.9 mm long and 0.4–0.6 mm wide.

Etymology: —The specific epithet “ ophioides ” originates from the ancient Greek word ὄφις (ophis), meaning snake or serpent, in reference to the conspicuously serpentine morphology of the spikes.

Habitat and distribution: — Limonium ophioides is exclusively found at the Maleas Peninsula of southeast Peloponnisos, localized along the rocky coastal area stretching between the settlements of Paleokastro and Tsoumala. It is found south of Agios Prokopios chapel and approximately 6 km linear distance south of Neapolis Voion town. Its habitat encompasses the rocky, calcareous segments of the coastline, and it is observed along a hiking trail and in proximity to a small dirt road. This species coexists with other halophytic plants such as Crithmum maritimum Linnaeus (1753: 246) , Lotus cytisoides Linnaeus (1753: 776) , Cichorium spinosum Linnaeus (1753: 813) , Frankenia hirsuta Linnaeus (1753: 331) , and Silene sedoides Poiret (1789: 164) . It thrives at 2 to 5 meters above sea level. It is worth noting that this particular coastline of the Maleas Peninsula poses significant accessibility challenges across extensive sections. While the species is considered as very local at present, the existence of additional populations in new locations difficult to access cannot be ruled out.

Phenology: —Flowering from June to October, fruiting from August to December.

Conservation status: —According to current knowledge, Limonium ophioides has a small and restricted population, with the total number of mature individuals estimated between 300 and 400, i.e., below the threshold for the Vulnerable category under Criterion D, as per IUCN (2022). Although it has an area of occupancy and an extent of occurrence of less than 10 km 2 and it is found at just one location, no imminent threats are identified to justify a higher risk classification. Hence, the species is categorized as Vulnerable D1, due to the low number of its mature individuals.

Reproductive pattern: —The investigation of the breeding systems in Limonium ophioides revealed a consistent pattern within its solitary population. Individuals exhibit Type A pollen, characterized by cob-like stigmas, or Type B pollen, with papillate stigmas. These morphological variations occur with similar frequencies throughout the population. Pollen viability ranges from relatively high (77%) to exceptionally robust (95%) across all individuals, indicating a strong reproductive capacity with a significant proportion of viable pollen grains capable of successful germination. Furthermore, viable pollen grains are tricolpate and exhibit consistent size, while non-viable ones are noticeably smaller, suggesting potential morphological differences associated with reproductive functionality. The combination of dimorphic pollen and stigmas that occur at about the same ratio, along with high pollen viability and consistent pollen characteristics, collectively support the conclusion that Limonium ophioides reproduces sexually.

Cytology: — Limonium ophioides is diploid with 2 n =2x=18 ( Fig. 3 ). Most chromosomes are submetacentric to acrocentric, and unequal in size. Three chromosome pairs are considerably longer, approximately two to three times the size of the remaining chromosomes. A small, satellited chromosome was also identified in the complement.

Taxonomic remarks:— Limonium ophioides is classified within the L. subgenus Limonium , specifically within the taxonomically complex “Mediterranean lineage” as defined by Koutroumpa et al. (2018). This clade comprises a diverse array of Mediterranean endemics, many of which have not been assigned to any specific section within the genus (Koutroumpa et al. 2018). Concerning morphology, L. ophioides is included within the informal “ L. cancellatum-dictyophorum ” group according to the classification of Brullo & Erben (2016). This group consists of sexual, diploid species with a chromosome number of 2 n =18 and shared morphological traits, like the green stems, the smooth to rugose leaves, the flexuous and reticulate inflorescences, and the small inner bracts. They are found along the Adriatic and Ionian coasts ( Bogdanović & Brullo 2015). In Greece, 13 species of this group are known, namely Limonium arcuatum Artelari (1984: 20) , L. cephalonicum Artelari (1984: 28) , L. antipaxorum Artelari (1984: 22) , L. ithacense Artelari (1984: 26) , L. saracinatum Artelari (1984: 25) , L. zacynthium Artelari (1984: 29) , L. phitosianum Artelari (1984: 30) , L. damboldtianum Phitos & Artelari (1981: 18) , all distributed on the Ionian Islands, and L. coronense Artelari (1984: 31) , L. pylium Artelari (1984: 23) , L. kardamylii Artelari & Kamari (1995: 131) , and L. messeniacum Artelari & Kamari (2000: 45) occurring along the western and eastern coasts of Peloponnisos ( Artelari & Kamari 1986, 1995, 2000). L. epiroticum Brullo ( Brullo et al. 2017) from the area of Parga, Epirus, is presumably diploid too. Limonium ophioides is morphologically most closely related to L. coronense , distributed along the coastline between Koroni town and Finikounda village at the southwestern tip of Peloponnisos, but differs primarily in the smaller size of spikes, spikelets, inner bracts, and calyces ( Fig. 7A,7C ), as well as in the curvature of spikes—serpentine to straight in L. ophioides compared to straight in L. coronense ( Fig. 8 )—and stem morphology—stems articulated and thickened, robust in L. ophioides compared to very flexuous and slender to slightly robust in L. coronense . The geographically nearest species within the same group of L. ophioides are L. messeniacum and L. kardamylii , located at the central peninsula of south Peloponnisos. However, the new species can be readily differentiated from both of them by its distinct habit and abundance of sterile branches. Finally, it can be distinguished from L. pylium and L. nichoriense (see below) by its glabrous stems and its laterally curved spikelets. The main morphological diagnostic characters between L. ophioides , L. nichoriense , L. coronense , and L. pylium are provided in Table 1 . No intermediates among L. ophioides and its closest relatives have been observed in the field.

Figures

FIGURE 1. Morphological features of Limonium ophioides. A. Habit. B. Leaf. C. Spike. D. Spikelet. E. Calyx. F. Seeds. Illustration by Lydia A. Papadopoulou based on herbarium material from the type locality.

FIGURE 2. Limonium ophioides A. Habitat. B. Habit. C. Leaves and stems. D. Detail of the inflorescence.

FIGURE 3. Mitotic metaphase plate of Limonium ophioides with 2n=2x=18. Scale bar = 10 μm.

FIGURE 7. A. Inner bracts of Limonium coronense, L. pylium, L. nichoriense, and L. ophioides, arranged from left to right. B. Base of stems, with L. coronense on top and L. nichoriense on the bottom. C. Calyces of L. coronense, L. pylium, L. nichoriense, and L. ophioides, displayed from left to right. D. Leaf apex comparison, with L. coronense on the left and L. nichoriense on the right.

FIGURE 8. Spikes of Limonium coronense, L. nichoriense, and L. ophioides, arranged from left to right.