Study on the Genus Drymaria (Caryophyllaceae)—A New Species from North-East India

3.1. Morphometric Data

The analyses of the characters allow the recognition of three distinct groups.

Concerning the hierarchical clustering (Figure 1), the cutoff dissimilarity point (1.35) defines three clusters, with each one comprising specimens referring to single species, i.e., Drymaria diandra, D. villosa, and Drymaria sp.

The PCA analysis shows that the cumulative percentage of eigenvalues for the first two axes is 78.76%, with the contribution given by the first component being 58.06% and that by the second component being 20.70%. The component1 vs. component2 graphs show three well-separated groups along the first component, whereas, along component2, two groups are partially overlapped (Figure 2). These three groups correspond to the populations of Drymaria diandra, D. villosa, and Drymaria sp., as displayed by the clustering. The highest contribution to the first component is given by the following characters: length and width of fruits, length and width of sepals, and length of stamens. The second component is mainly related to the length and width of gynoecium, length of petiole, seed diameter, width of petals, and length of bracts.

The DA, carried out using the names of the species (three groups: Drymaria diandra, D. villosa, and Drymaria sp.), predicted three clearly separated groups (Figure 3) based on the first two discriminant functions, which explain 100.0% of the total variation [eigenvalues: 79.7% (first function) and 20.3% (second function)]. These groups correspond to D. diandra, D. villosa, and Drymaria sp.

The results of the MANOVA show significant differences at both species and population levels. The probability level is less than 0.000001 for all the statistical tests considered (Wilks’ lambda, Hotelling–Lawley trace, Pillai’s trace, and Roy’s largest root). F-ratios are high, ranging from F = 27.03 to 2020.7 (populations as groups; Table 4) and F = 1639.56 to 4011.09 (species as groups; Table 5).

3.3. Taxonomic Treatment

Both the morphological and molecular results obtained in the present research demonstrated that the Drymaria populations growing in Kohima District (Nagaland region, NE India) are different to the other Indian Drymaria species. Consequently, here, we propose describing the population of Drymaria as a new species for science. A complete taxonomic treatment of Drymaria taxa occurring in India follows.

1.

Drymaria anilii S. Arya, Suresh & Iamonico, sp. nov. (Figure 5).

Holotype: INDIA. Nagaland: Kohima District, Kisama Village, 1800 m a.s.l., 25°37′35″ N 94°60′48.9″ E, 20 October 2021, Arya 730 (DMP!; isotypes: DMP!, RO!).

Diagnosis. Drymaria anilii resembles D. diandra, from which it differs in terms of inflorescence (sessile in a single terminal flower vs. cymose with 10–15 flowers), bracts (foliaceous, glabrous, 2 cm long vs. non-foliaceous, pubescent, less than 5 mm long) pedicel (glabrous vs. glandular), sepal (obtuse or rounded at the apex, incurved at the margin vs. acute at the apex, not incurved at the margin), petal (obtuse or rounded at the apex and linear vs. acute at the apex and ovate), fruit (ellipsoidal, 6 mm long vs. ovate, 3 mm), pollen (spherical with depressed non-prominent pores vs. ellipsoid with prominent pores), and seed surface architecture (small mamillated spots which form a star-like radiating pattern vs. large spinulate spots that cross each other).

Description (macromorphology). An annual herb (therophyte) which is slender, branching from the base, and 10–12 cm long. The root is thin, producing many short horizontal spreading branches, sometimes originating from the lower stem nodes. The stem is prostrate or ascending and erect pubescent with glandular multiseriate trichomes. The leaves are opposite, orbicular to cordate (1.3–2.1 cm × 1.2–1.5 cm), glabrous in the adaxial side, and sparsely pubescent on the abaxial surface; the apex is rounded or acute, and the base is cordate; the petioles are 1–5 mm long, hairy; and the stipules are minute, at 0.1 mm long. There are inflorescences in the reduced cyme (up to three-flowered); the peduncles are 1.5–2.5 mm long and hairy; the bracts are linear to lanceolate and 2 mm long; the pedicels of the flowers are 1–2 mm long and sparsely pubescent; the five sepals are, 1.2–1.4 × 0.6–0.7 mm long, lanceolate, and the apex is acute or obtuse and hairy; the five petals are 1.2–1.3 mm long and bifid (rounded lobes); the stamens are five fewer in number than the sepals with a 0.5 mm long filament and oblong, yellow-brown anthers; the staminode is absent; the ovary is ovoid or globose and 0.7–0.8 mm, and the style is 0.4–0.6 mm long and parted into four at the apex with glands. The capsules are ovoid, 1.7–1.9 mm long, equaling or slightly exceeding the sepals, and opening by four valves to the base. The seeds are brown and reniform.

Description (micromorphology; Figure 6). The pollen grains are spheroidal, poly-pantoporate, and 8.16–10.64 µm in diameter, with 5–6 visible pores. The pore margin or aperture is well demarcated, at about 2 µm. The pores are 3.2–3.3 µm in size. The surface is micro-echinate; the echinates are blunt or appear like dots which are fused. Ektexinous bodies are present inside the pore, minute, and number 4–8 fused, but the apex is sharp and free.

The seeds are reniform with a circular base (0.548–0.765 × 0.614–0.761 mm). The margin is wavy, and the tubercles are short and prominent; small mamillated spots which form a star-like radiating pattern are visible on the surface. The dots form a “V” shape that do not cross each other.

Etymology. The species is named in honor of Dr. V.S. Anil Kumar, Principal of Government College Kasargode, Kerala, India, in recognition of his outstanding contributions to the field of plant taxonomy of the Western Ghats. Dr. Anil Kumar is acknowledged as a great teacher and motivator in the field.

Habitat distribution (Figure 7) and phenology. Drymaria anilii is known from only the locus classicus (Nelliyampathy hills of Palakkad District at an elevation of 1250–1400 m a.s.l.), where it grows along the grasslands. Each population spreads over an area of less than 5 km. Flowering and fruiting times are June to November.

Conservation status. Even though the plant propagates through vegetative propagation (rooting at the nodes), the number of individuals is very small and they are vulnerable to the severe grazing and stamping of elephants. There are possibilities of the species occurring in other parts of the Western Ghats. More extensive studies on the species are required to reach a conclusion on its conservation status. Therefore, by following the IUCN Red List criteria [29], Drymaria anilii is assessed as Data Deficient (DD).

Taxonomic notes. The three Drymaria species occurring in India (D. cordata, D. diandra, and D. villosa) usually have a restricted distribution area and can be found across the Himalayan belts and the hilltops of the Western and Eastern Ghats. Based on the morphology of D. anilii, especially its stipulate leaves, terminal solitary cyme, bifid petals, 2–5 stamens, usual three styles, and one or many seeds, it would belong to the series Cordatae [9] (p. 245). The series is represented by five species, four subspecies, and two varieties in Duke’s monograph (Drymaria gracilis Schltdl. & Cham., D. gracilis subsp. carinata (Brandegee) A.J.Duke, D. glandulosa C.Presl var. glandulosa, D. glanduosa var. galeottiana (Briq.) A.J.Duke, D. xerophylla A.Gray, D. ladewih Rusby, D. cordata (L.) Willd. ex Roem. & Schult. and D. diandra Blume). All these mentioned species, except for D. cordata and D. diandra, have a distribution in the Americas (the USA, Argentina, and Mexico [8]). Note, however, that a comprehensive molecular study to demonstrate that Duke’s classification is natural is lacking. Consequently, the inclusion of D. anilli in the Ser. Cordatae is preliminary and deserves further investigations.

2.: Drymaria cordata (L.) Willd. ex Schult., in J.J.Roemer & J.A.Schultes, Syst. Veg., ed. 15[bis]. 5: 406 (1819) ≡ Holosteum cordatum L., Sp. Pl. 1: 88 (1753) ≡ Cerastium cordatum (L.) Crantz in Inst. Rei Herb. 2: 400 (1766).

3.: Drymaria diandra Blume, Bijdr. Fl. Ned. Ind.: 62 (1825) ≡ Drymaria cordata subsp. diandra (Blume) J.A.Duke in Ann. Missouri Bot. Gard. 48: 253 (1961).

Note. The isotypes listed above (BM000946422 and MO216778) were not reported by neither Mizushima [32] (p. 81) nor Duke [5] (p. 253).

4.: Drymaria villosa Cham. & Schltdl., Linnaea 5(2): 232–233 (1830) subsp. villosa ≡ Drymaria cordata var. villosa (Cham. & Schltdl.) Rohrb. in C.F.P.von Martius & auct. suc. (eds.), Fl. Bras. 14(2): 260 (1872).

Note. Duke [9] (p. 226) stated “Drymaria villosa Cham. & Schlecht. in Linnaea 5:232. 1830. (HOLOTYPE: Schiede & Deppe 505; in aquosis prope Jalapam, B, probably destroyed; isotype at LE!”. Collections at B were mostly destroyed during World War II, as highlighted by many authors (e.g., [33,34,35,36,37]). According to Art. 9.10 of the Shenzhen Code [13], the term “isotype” used by Duke [9] (p. 226) is to be corrected to lectotype.

3.4. A Diagnostic Key of the Members of Drymaria Series Cordatae (Sensu Duke 1961)

1a. Petals equal the sepals; seeds numerous, less than 1 mm, broad………………………………………..2

1b. Petals shorter than sepals; seeds one to many, 0.5–2.0 mm broad………………………………………4

2a. Leaves ovate–reinform; stipules longer than the petiole; petals divided by about half

the length; lobes 2–4, nerved………………………………………………………D. glandulosa var. galeottiva

2b. Leaves deltoid; long petiole; stipules shorter than the petiole; petals divided by more

than half its length; 1 lobe, nerved…………………………………………………………………D. gracilis s.l.

3a. Stipules lacerate; seeds coarsely tuberculate; tubercles prominent………………………subsp. gracilis

3b. Stipules entire; seed merely verucate with remote protuberance………………………..subsp. carinata

4a. Sepals slightly longer than petals; seeds 0.5–0.8 mm; stipules lacerate…………………………………5

4b. Sepals twice the length of petals; seeds 0.7–2.0 mm; stipules entire…………………………………….6

5a. Flowers in terminal cymes; leaves petiolate; petals bifid;

stamens 3–5…………………………………………………………………………D. glandulosa var glandulosa

5b. Flowers clustered in the axil of the leaves; petals bifid or ligulate;

stamens 2–3……………………………………………………………………………………………D. xerophylla

6a. Leaves deltoid–ovate; stipules entire; seeds 3–5, styles united for half the length…………..D. ladewii

6b. Leaves reniform, stipules lacerate, seeds 1–12, style free…………………………………………………7

7a. Flowers campanulate; pedicels glandular; seeds 1–12, broad……………………………………………8

7b. Flowers pyriform; pedicles eglandular; seeds 1–2, broad……………………………………..D. diandra

8a. Seeds have small mamillated spots with a star-like radiating pattern; pollen spherical,

depressed with non-prominent pores……………………………………………………………………D.anilii

8b. Seeds have large spinulate spots that cross each other; pollen oblong with prominent

pores………………………………………………………………………………………………………D. cordata

3.5. Conclusions

Drymaria, a genus belonging to the large tribe Polycarpaeae of the Caryophyllacecae family, is poorly known from a taxonomical point of view. In fact, a recent comprehensive study is lacking, and the last one was published about 70 years ago by Duke [9]. Also, molecular data are few, and those available are included in a wider paper on the whole family [2]. Among the important gaps in morphological and molecular studies of Drymaria, there are, e.g., the Andean species [12], but also Asian species (three—D. cordata, D. diandra, and D.villosa—according to the Plants of the World Online database [8]) which were not investigated in detail. So, our study, which deals with these three species, represents the first one for the continent. Furthermore, the combined use of both morphometric and molecular techniques appears to have never been considered before us for Drymaria and proved to be very useful for analyzing taxonomically critical plant taxa, as highlighted by other authors regarding Caryophyllales groups, e.g., Allmania R.Br. ex Wight [38], Dianthus L. [39], Limonium Mill. [40], or Salicornia L. [41].

Source link

Sindhu Arya www.mdpi.com

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Study on the Genus Drymaria (Caryophyllaceae)—A New Species from North-East India

3.1. Morphometric Data

3.3. Taxonomic Treatment

3.4. A Diagnostic Key of the Members of Drymaria Series Cordatae (Sensu Duke 1961)

3.5. Conclusions

Greenberg

3.1. Morphometric Data

3.3. Taxonomic Treatment

3.4. A Diagnostic Key of the Members of Drymaria Series Cordatae (Sensu Duke 1961)

3.5. Conclusions

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