Dichoropetalum andacii Akpulat, G.E. Genç & Akalın, 2024

Akpulat, H. Aşkin, Ecevit-Genç, Gülay, Akalin, Emine & Özcan, Taner, 2024, Dichoropetalum andacii (Apiaceae), a new species from Türkiye, Phytotaxa 660 (2), pp. 123-136 : 125-130

Dichoropetalum andacii Akpulat, G.E. Genç & Akalın sp. nov. ( Fig. 1 )

Type: — TÜRKİYE. Antalya, Alanya-Mahmutlar district, forest area, 1100 m, 16 July 2008, Akpulat 4351 (holotype: ISTE 118641!).

Diagnosis: — Dichoropetalum andacii is related to D. chryseum ( Fig. 2 ), differing by having 20–30 (vs. 10–20) rayed umbels, 8–9 (vs. 6–7) lanceolate bracteoles, 4–6 × 2–2.8 (vs. 6–8 × 3–4) mm fruits.

Description: —Perennial with a thick rootstock. Stems 40–120 cm tall, striate to grooved. Leaves mostly basal leaves 2-pinnate, ultimate segments simple to lobed. Synflorescence a junciform panicle bearing compound umbels. Umbels 20–30 rayed, rays unequal, glabrous, 2–3.5 mm, Bracts 0–1, linear-lanceolate 5–6 × 2–3 mm. Bracteoles 8–9, lanceolate, 2–5 × 0.5–1 mm. Flowers small, c. 2 mm in diam., 6–8 per umbellule. Pedicels 6–8 mm. Sepals obsolete. Petals yellow, 0.7–1 mm glabrous. Stamens c. 0.8 mm. Stylopodium broadly conical, styles c. 0.6 mm, slender, deflexed. Fruit oblong to oblong-elliptic, brown when ripe, 4–6 × 2–2.8 mm, with lateral wings 0.6–0.7 mm, compressed dorsally, dorsal ribs are prominent. Chromosome number: 2n = 22.

FIGURE 3. Distribution of D. andacii () and D. chryseum (°) in Turkey

Phenology: —The flowering time of D. andacii is from June to August, its fruiting time from July to September.

Etymology: —The name Dichoropetalum andacii was given in dedication to Andaç, son of the first author.

Ecology, distribution and proposed conservation status: — The new species grows in Pinus forest area, between 1100 and 1150 m a.s.l. Endemic to Antalya (Fig. 3), the species is known only from one population in the type locality and the estimated area of occupancy is less than 10 km 2. Additionally , the type locality is near a picnic area ; therefore, the area is under pressure due to human impact. Thus, it is suggested that this new species should be placed under the IUCN threat category ‘Critically Endangered’ (CR) [criterion B2 ab (ii)] ( IUCN 2022).

Pollen and mericarp surface morphology: —Mericarp surface cells are arranged at random, cell borders are raised, cuticle striate, anticlinal walls wavy, periclinal walls concave, epicuticular wax tuberculate ( Fig 4 ).

The pollen grains are monad, small, tricolporate, and isopolar. While the shape of the pollen grains in the equatorial view is elliptical, their shape in the polar view is lobate. Monads are prolate, polar axis (P) = 22.4 ± 0.5 μm, equatorial axis (E) 12.5± 0.8 μm, P/E = 1.8. Exine sculpturing is rugulate ( Fig 5 ).

Carpological characters: —Mericarps 4–6 × 2–2.8 mm, compressed dorsally, dorsal ribs are prominent. Vittae prominent, 4 dorsal (1 vitta in each vallecula), 2 commissural; vittae width (parallel to commissure) are 0.40–0.69 mm, vittae length are 0.157 –0.220 mm. Vascular bundles are located in each rib, all vittae are situated between the vascular bundles. Mesocarps are 0.125 –0.157 mm in thickness. Parenchyma cells of mesocarp with lignified pitted walls in marginal ribs. The ratio of endosperm thickness to its width is 3.4 ( Fig 6 ).

Karyology: —The chromosome number of the new taxon is 2n =22 ( Fig 7a ). The shortest chromosome length is 1.84 μm, the longest is 2.55 μm, and the total haploid chromosome length (THL) is 23.88 μm. The karyotype formula of this taxon consists of 16 median pairs and 6 submedian pairs. Intrachromosomal asymmetry (MCA) is 18.37 and the interchromosomal asymmetry index (CVCL) is 10.09. The ideogram was drawn based on the centromeric index in Figure 7c .

Phylogenetic analyses:— Based on similar studies, members of the Conium genus were chosen as the most distant outgroup in our study. 536 DNA sequence characters were analyzed using 37 taxa in total with the outgroups. The consistency index (CI) and homoplasy index (HI) of the phylgenetic tree was 0.786 and 0.214, respectively. 392 characters of 536 sequences were constant for all taxa, and a number of parsimony-informative characters was 105 ( Fig. 8 ).

Phylogenetic analysis results also support the separation of the new species. Molecular data have shown that D. chryseum and D. palimbioides species analyzed in this study that are growing in Turkey are different from some Dichoropetalum species obtained from N.C.B.I. (National Center of Biotechnology Information). When the newly described species, Dichoropetalum andacii , was analyzed it was observed that its closest relative is D. chryseum . The differentiation of D. andacii from D. chryseum individuals is well supported by high values (PP: 0.9 and BS: 82). Furthermore, it is observed that three individuals of D. chryseum and two individuals of D. andacii (examined in this study) are most closely related to individuals of D. chryseum obtained from the N.C.B.I. (PP: 1, BS: 95) but the samples obtained from the GenBank do not share the same clade with the samples analyzed in this study. This indicates that there are genetic differences between individuals of D. andacii and D. chryseum examined in this study and D. chryseum individuals obtained from the GenBank.

Additionally, it was observed that D. palimbioides , which is morphologically similar to D. andacii , is placed in a different clade. Similarly, two individuals obtained from the GenBank and four individuals of D. palimbioides used in this study are also more distinct from one of the individuals of D. palimbioides obtained from the GenBank (MK328074).

The new species examined in this study, D. andacii , was clearly located together with the members of Dichoropetalum clade. As seen in the region indicated with the arrow symbol, Dichoropetalum members analyzed in the study are distinguished from members of other genera with values of 0.9/98 (PP/BS). In addition, D. andacii and D. chryseum are the closest species, while D. palimbioides is the closest sister group to these two species members ( Fig. 8 ).

Figures

FIGURE 1. Holotype of Dichoropetalum andacii Akpulat, G. E. Genç & Akalın

FIGURE 2. Dichoropetalum chryseum (Boiss. & Heldr. ex Boiss.) Pimenov & Kljuykov (ISTE 118642).

FIGURE 4. SEM micrographs of mericarp surface of Dichoropetalum andacii (a, c) and D. chryseum (b, d).

FIGURE 5. SEM micrographs of pollen grains of Dichoropetalum andacii (a, c) and D. chryseum (b, d).

FIGURE 6. Fruits of Dichoropetalum andacii (a, b) and D. chryseum (c, d). Mericarp cross-section of Dichoropetalum andacii (e) and D. chryseum (f).

FIGURE 7. Somatic chromosomes, and idiogram of Dichoropetalum andacii (a, c) and D. chryseum (b, d) Scale bars = 2 μm.

FIGURE 8. Phylogenetic tree based on nrITS sequences (PP values is shown in left side and BS values is shown in right side in the branches, GenBank accession numbers are given in front of the sequences obtained from GenBank and backside of examined specimens marked with star symbols)