Cerastium cylindricum Poursakhi & Assadi, 2017

Poursakhi, Katayoun & Assadi, Mostafa, 2017, A new endemic species of Cerastium (Caryophyllaceae) from Iran, Phytotaxa 312 (2), pp. 287-292 : 288-289

Cerastium cylindricum Poursakhi & Assadi , sp. nov. ( Fig. 1 ).

Type:— IRAN. Tehran: S of Plour, Bazm mountains, 2400 m, 12 May 1973, Arazm & Bazargan 2545 (holotype TARI!).

Diagnosis:—Species nova a Cerastium dichotomum similis sed foliar pilis eglandulosis, pedicellus calyce brevioribus, sepalis extremum brevioribus, apice acuminatibus, styllis brevioribus, Capsulis brevioribus.

Description:—Annual, caespitose, 7.5–15.0 cm high, with glandular and eglandular hairs. Stems numerous. Middle leaves oblong-lanceolate or oblanceolate (10–26 × 1.7–3.0 mm), obtuse or rounded; upper leaves lanceolate or oblong-lanceolate (10.0–14.5 × 2.5–3.0 mm), obtuse. Bracts herbaceous; lower bracts lanceolate or lanceolate-ovate (7–13 × 2.0– 2.5 mm), obtuse; upper bracts, lanceolate (4.5–8.0 × 1–2 mm), obtuse. Pedicels equal or shorter than sepals, patent or erect in fruiting stage. Sepals lanceolate, acuminate; outer sepals (7–8 × 2.0– 2.2 mm) very narrowly scarious at tips and at margins. Petals 5, obovate (4–6 × 2.5–3.5 mm), bilobed, with a sinus 1.0– 1.2 mm long, glabrous, equal or shorter than sepals. Stamens 10; filaments 2–3 mm long, glabrous; anthers 0.2–0.4 mm long. Styles 5, 0.4–0.6 mm long. Capsules (8–13 × 1.5–2.5 mm) straight or curved; teeth 10, 0.5–1.0 mm long, flat. Seeds 0.8–0.9 mm long, 0.7–0.8 mm wide, ± circular, dull brown, with obtuse or rounded dome shaped tubercles.

Etymology:—The specific epithet refers to cylindrical and rough stem.

Phenology: —Flowering time late May − early June; fruiting time July − August.

Distribution and Habitat:—This new species has been known only from the type locality, Tehran Province, South of Plour, Bazm mountains, at 2400 m a.s.l. The new species can be considered endemic to N-Iran, representing an Irano-Turanian element. The closest relative C. dichotomum Linnaeus (1753: 438) occurs in Spain, Greece, N- Africa, SW- and C-Asia and in other countries ( Möschl 1988).

Taxonomic notes:—The new species belongs to subg. Cerastium sect. Schizodon . In subgen. Cerastium styles are 5, and teeth of capsules are with 10 dehiscent and in sect. Schizodon petals are shorter than calyx, lobed, capsules are cylindric-conical, many times as long as calyx, with erect teeth ( Möschl 1988).

Cerastium cylindricum differs from C. dichotomum in having shorter stem (6–15 vs. 6.5–28.0 cm), shorter upper leaves) 10.0–14.5 vs. 12–42 mm) and narrower upper leaves (2.5–3.0 vs. 3–9 mm), shorter outer sepals (7–8 vs. 8.5–13.0 mm) and narrower (1.8–2.2 vs. 2–3 mm), shorter styles (0.4–0.6 vs. 0.6–0.8 mm long) and shorter capsule (8–13 vs. 15–23 mm long) (see Table 1).

In the family Caryophyllaceae , the seeds characters have high taxonomic value (see e.g., Kanwal et al. 2012). The ornamentation features of the seed surface and its relief are different from one species to another ( Yildiz 2002).

As regards the micromorphological characters of seed of Cerastium cylindricum , some important features can be highlighted ( Table 2). The morphological characteristics of seeds were studied according to different characters used by Yildiz (2002) and Fawzi et al. (2010). The most important differences between seeds of C. cylindricum and C. dichotomum are shape of testa cell (octapus vs. stellate), number of suture point per plate (6–9 vs. 8–10), suture outline (± oblong vs. V- shaped), seed verrucae shape (dome shaped vs. convex and short conical) and seed verrucae tip (obtuse vs. ± acute) ( Figs. 2–3 ).

Figures

FIGURE 1. Cerastium cylindricum.

FIGURE 2. SEM seed photographs of Cerastium cylindricum. A) General appearance, B) Lateral surface, C) Lateral surface (marginal part).

FIGURE 3. SEM seed photographs of Cerastium dichotomum. A) General appearance, B) Lateral surface, C) Lateral surface (marginal part).