Eriocaulon parvicephalum A.M.Darshetkar, R.K.Choudhary, M.N.Datar & S.A.Tamhankar, 2017

Darshetkar, Ashwini M., Datar, Mandar N., Tamhankar, Shubhada & Choudhary, Ritesh Kumar, 2017, Eriocaulon parvicephalum (Eriocaulaceae), a new species from Western Ghats, India, Phytotaxa 303 (3), pp. 233-242 : 235-241

Eriocaulon parvicephalum A.M.Darshetkar, R.K.Choudhary, M.N.Datar & S.A.Tamhankar , sp. nov. ( Figs. 1 , 3 )

Type:— INDIA. Maharashtra: Sindhudurg District, Malvan Taluka, Achre Plateau near Gad River, 9 September 2014, R. K. Choudhary & M. N. Datar 29530 (holotype AHMA, isotype BSI).

Similar to Eriocaulon palghatense but differs by acuminate spathe apex (vs. obtuse spathe apex), eglandular petals of male flower (vs. glandular petals of male flower), and two rectangular seed coat appendages per cell (vs. appendages in the form of split ribbon-like bands).

Acaulescent herbs. Rootstock absent. Leaves 4–6 mm × 0.5–1 mm, rosulate, linear–lanceolate, acuminate, glabrous. Peduncles few, up to 2 cm long, sparsely hairy, rarely glabrous, sparsely hoary towards the apex. Sheaths up to 6 mm long, glabrous; limb lanceolate with acute apex, entire. Heads obovoid, ca. 1 mm across, grey; receptacles convex, glabrous; involucral bracts ca. 1 × 1 mm, obovate, obtuse, chartaceous, glabrous, black; floral bracts ca. 1 × 0.5 mm, oblanceolate, subacute, chartaceous, hoary towards apex, black. Male flowers: Pedicels very small. Sepals connate, ca. 0.5 × 0.25 mm, 3-lobed with acute lobes, sparsely hoary towards apex. Petals 3, hyaline, eglandular. Anthers 6, globose, black. Female flowers shortly pedicellate. Sepals 3, free, ca. 0.75 × 0.1 mm, linear, chartaceous, hoary towards apex, black. Petals 3, free, ca. 0.75 × 0.2 mm, spathulate, hyaline, with a black gland. Ovary sessile, ellipsoid, style trifid. Seeds: Length: 0.3 ± 0.1 mm, Width: 0.1 ± 0.1 mm, oblong–ellipsoid, acute, seed surface granulate, reticulate cells, transversely elongated, appendages 2, rarely three from transverse radial walls, rectangular or in the form of ribbon-like bands.

Etymology: —The specific epithet refers to the small size of the inflorescence of the new species.

Morphological comments: —The new species ( Fig. 1 ) is morphologically similar to Eriocaulon palghatense but differs from that species in having an acuminate spathe apex, eglandular petals of male flower, and two rectangular seed coat appendages per cell ( Fig. 4 , Table 2). The new species belongs to Section VII as per the sectional treatment of Ansari & Balakrishnan (2009). As such we tried to include the species from Section VII that are morphologically similar to the new species. Eriocaulon palghatense ( Fig. 2 ) also shows some morphological similarity with E. conicum (Fyson 1921: 260) Fischer (1931: 1620) , an endemic and rare species that grows in western peninsular India (Karnataka, Kerala and Tamil Nadu) at an elevation of about 1000 m. The new species, by contrast, grows at low elevations. Despite extensive searching, we were not able to locate and make new collections of E. conicum for inclusion in our phylogenetic analyses. The new species also shows some morphological similarities with E. quinquangulare , as both species have two to four seed coat appendages in the form of ribbon-like or rectangular bands (a synapomorphic feature of Section VII). However, E. quinquangulare differs from the new species in having glabrous peduncles up to 40 cm long, straw colored involucral bracts and obtuse lobes of male sepals.

Phenology: —August–October. The plant is an annual that germinates after the monsoon (August). Leaves appear in the same season and the flowers remain until September. Seeds are set and dispersed in October. As per Raunkiaer’s life form ( Cain 1950) this species can be categorised as a therophyte.

Distribution & Habitat: — Eriocaulon parvicephalum grows as a part of the ephemeral flush vegetation on lowlevel soil-covered ferricretes in association with E. eurypeplon , Rotala sp. , Eleocharis sp. and Ischaemum sp. The species is known only from the type locality, where apparently it is endemic ( Fig. 3 ). Efforts to find the new species in surrounding areas were unsuccessful.

Conservation Status: —Data Deficient (DD) following IUCN (2001) criteria. The single known locality of this species comprises a small population with about 100 individuals. The single population is not in a protected area, hence its survival is threatened. However, quantitative demographic data is needed to better assess its threat status, including detailed investigation of the effects of anthropogenic factors on the habitat.

Phylogenetic relationships: —This is the first attempt to carry out phylogenetic study of Indian species of Eriocaulon . We included representatives from all closely allied sections as per the sectional treatment of Ansari & Balakrishnan (2009).

Summary statistics from the molecular analyses are summarized in Table 3. The three species of Sect. VII, including E. parvicephalum , form a strongly supported clade (BP = 100, PP = 1), and E. palghatense and E. parvicephalum are moderately or strongly supported sister taxa (BP = 92, PP = 0.71). Species of Sect. III and Sect. VI are intermixed and form a strongly supported clade (BP = 100, PP = 0.98), thus these sections are not monophyletic in their current circumscriptions. The ITS sequence of the new species differs from that of E. palghatense by nucleotide substitutions at the 60 th (transversion) and 542 nd (transition) positions, whereas the psbA–trnH sequence differs by nucleotide substitutions at the 186 th and 239 th positions, both transitions. The trnL–F region of E. palghatense is shorter (957 bp) than the rest of the sampled species (1092 bp). There are 20 substitutions in the trnL–F region between E. palghatense and the new species. Deletions were observed at four places in E. palghatense . We also collected E. truncatum Buchnan –Hamilton ex Martius in Wallich (1832: 29), another member of Section VII, but the species could not be included in the combined analysis due to problems in amplifying ITS and trnL-F regions. However, psbA-trnH amplified well, and in an independent analysis, E. truncatum nested within the Section VII clade (data not shown).

Total nucleotide sites after alignment 2571

Constant sites 596

Variable but parsimony uninformative sites 401

Parsimony informative sites 1574

Length of majority consensus tree 2845

Consistency Index 0.912

Retention Index 0.931

Homoplasy Index 0.088

Length of entire ITS region 560–760 bp

Length of psbA–trnH region 555–636 bp

Length of trnL–F region 956–1090 bp

SEM information: —Applicability of seed coat morphology for identification of Indian Eriocaulon species was highlighted by Nair (1987). Variation in the shape of seed, orientation of seed coat cells and structure and number of seed coat appendages are useful for delimiting Eriocaulon species. Our SEM studies support the recognition of the new species. Eriocaulon parvicephalum can be differentiated from E. palghatense in having two rectangular seed coat appendages per cell (vs. appendages in form of split ribbon like bands in E. palghatense ). A photo plate showing seed photomicrographs of the whole seed and seed coat appendages of E. parvicephalum and closely allied species is presented ( Fig. 4 ). All the species included in the study have transversely elongated seed coat cells ornamented by seed coat appendages ( Fig. 4 , Table 4). The phylogenetic analysis also revealed significance of seed coat morphology in classifying Indian Eriocaulon species. Species with ribbon shaped or rectangular seed appendages (Sect. VII) clustered together (BP = 100, PP = 1) whereas species with setiform seed coat appendages (Sect. III and VI) formed a monophyletic group (BP = 100, PP = 0.98).

Though useful to study inter- and infrageneric phylogeny of Eriocaulaceae, ITS was difficult to amplify and sequence in the present study. Amplified products often showed double or multiple bands and in some cases fungal sequences were amplified instead of Eriocaulon sequences. Unwin (2004), while reviewing the potentially useful markers for Eriocaulaceae , encountered the same problem. He obtained multiple bands of various sizes while amplifying ITS region of all Eriocaulaceae taxa.

Figures

FIGURE 1. Eriocaulon parvicephalum. a. Habitat. b. Habit. c. Peduncle. d. Involucral bract. e. Floral bract. f. Female flower. g. Male flower. h & i. SEM images of seed. (All images from AHMA 29530)

FIGURE 2. Eriocaulon palghatense. a. Habitat. b. Habit. c. Involucral bract. d. Floral bract. f. Male flower. g. Female flower. e & h. SEM images of seed. (All images from AHMA 29538)

FIGURE 3. Location of the type locality of E. parvicephalum with state and Western Ghats boundary. Inset: Location of E. parvicephalum in India

FIGURE 4. Scanning Electron photomicrographs of seed and seed coat appendages. a & b. E. parvicephalum (AHMA 29530). c & d. E. palghatense (AHMA 29538). e & f. E. truncatum (AHMA 29550). g & h. E. cuspidatum (AHMA 29553). i & j. E. eurypeplon (AHMA 29549). k & l. E. sedgwickii (AHMA 29534). m & n. E. fysonii (AHMA 29531). o & p. E. robustobrownianum (AHMA 29537). q & r. E. parviflorum (AHMA 29546). s & t. E. richardianum (AHMA 29545). u & v. E. lanceolatum (AHMA 29535). w & x. E. xeranthemum (AHMA 29542). Scale bars = 100 μm (Figs. a, c, e, g, i, k, m, o, q, s, u, w), 20 μm (Figs. b, d, f, h, j, l, n, p, r, t, v, x).