Sida gathwalarum Sumit Malik, Inam Malik & Vijai Malik sp. nov.

Fig. 1

Type.

India • Uttar Pradesh: Meerut Cantonment, 29.007637, 77.714272, 16 November 2025, Sumit Malik & Vijai Malik 1706 (Holotype BSD 137791!; Isotypes BSD 137790!; DD S-1012!, S-1013! & S-1014!).

Diagnosis.

This species closely resembles Sida angustifolia Mill. in having, erect branched subshrubs, with branches alternate and spiral terete, pubescent with stellate hairs, calyx similar in shape with similar type of simple and stellate hairs in both species. Filaments and staminal tube also bearing similar type of simple and transparent glandular hairs but differing conspicuously in several vegetative and reproductive characters. Erect, up to 2 m tall (vs. 1 m tall). Leaves alternate and spiral, variable from narrowly lanceolate to ovate (vs. linear spear-shaped), base cuneate to rounded (vs. truncate or cordate at base), 3 (- 5) nerved at base (vs. only three nerves at base). Petioles 2.0–5.0 mm (vs. 5.0– 45 mm) without spiny emergence (spur) at base (vs. three spiny emergences spur present at base of leaf). Stipules are linear lanceolate in shape, 1.5–3.0 × 0.5–1.0 mm, subequal (vs. 5.0–7.0 × 1.0 mm, falcate, equal in shape) furnished with both simple and stellate hairs along the margins and on both surfaces. Peduncle 1.0–2.0 mm; pedicel 1.5–2.5 mm, articulation usually present below the middle (vs. peduncles 2.5–3.0 mm; pedicels 1.0–2.0 mm in flowers, articulation above the middle), Petals retuse to nearly entire at apex (vs. deeply emarginate notch at apex). Styles dissimilar in size (vs. similar in size), yellow in color. Esquizocarp indehiscence (vs. dehiscence), fruiting calyx soft and compressible. Mericarps 5–6, heteromorphic (vs. mericarps five, not as in Sida gathwalarum), mature mericarps trigonous – globose, 3.0–3.5 × 1.0–2.0 mm (vs. 4.0–4.2 × 2.0– 2.2 mm), their surfaces coarsely rugose to tuberculate, accrescent calyx hardly becomes empty, the mericarps remain enclosed and are not shed easily. Each mature mericarp possesses a shallow, broad, U-shaped apical notch. Seeds subtrigonous (vs. trigonous), slightly asymmetrical with unequal sides, one angle broader and more obtuse, dorsal ridge less sharp and more rounded, glabrous but shortly hairy at the hilum (vs. dorsal ridge very sharp, pointed, glabrous, granular at hilum), and uniformly dull brown to grey-brown (vs. variable in color brownish to black) (Table 1).

Description.

Erect, highly branched, suffrutex up to 2 m tall. Generally, stem green rarely bicolorous with one face green and the opposite brownish. Branches alternate and spiral, terete, pubescent with stellate hairs. Leaves 5.0–45 × 1.0– 17 mm, alternate and spiral (Fig. 1 B, C), variable from narrowly lanceolate to ovate, apex acute to acuminate, base cuneate to rounded, pulvinus, whole margin serrulate (Fig. 1 F, G), adaxial surface sparsely to coarsely pubescent with minute stellate and simple hairs, abaxial surface densely covered with minute stellate hairs (Fig. 1 E); venation pinnate, midrib prominent on lower surface, 3 (- 5) - nerved at base, lateral nerves 4–7 pairs. Petiole 2.0–5.0 mm with simple and stellate hairs without spiny emergence (spur) at base. Stipules narrowly lanceolate to linear lanceolate, 1.5–3.0 × 0.5–1.0 mm, subequal, 3–5 nerved, deciduous with simple and stellate hairs on margins and both surfaces (Fig. 1 D). Flowers axillary, usually two or more, pale yellow, bisexual. Peduncle 1.0–2.0 mm; pedicel 1.5–2.5 mm, articulation usually present below the middle, longer or shorter than stipules. Calyx five-lobed divided in middle, lobes 5.0–6.0 × 2.0–3.0 mm, accrescent with fruits, campanulate, venation 10 nerved, margin ciliate, outer surface pubescent with simple and stellate hairs, inner surface glabrous (Fig. 1 H – J). Corolla pale yellow, petals 5, 7.0–9.0 × 4.0– 4.5 mm, retuse to nearly entire, twisted aestivation, minute simple and glandular hairs on outer surface and margin, 9–10 nerves from base, branched (Fig. 1 K – M). Stamens numerous (27–30 in five bundles), monadelphous, staminal tube ca. 3.5 mm, pubescent with transparent simple and glandular hairs (vs. 2.0– 2.5 mm long, stellate-pubescent), anthers yellow, reniform, filaments 1–1.5 mm, pubescent (same as on stamina tube). Carpels 5–6, ovary hairy, styles 3.8–4.5 mm, unequal in length, divided almost from the base, yellow, appressed hairs on style, stigma capitates, and yellow (Fig. 1 N, O); axile placentation and ovules do not appear exactly equal in size (Fig. 1 P). Esquizocarp indehiscence, mericarps 5 (- 6), heteromorphic (Fig. 1 R), unequally filling accrescent calyx, fruiting calyx soft and compressible, accrescent calyx hardly becomes empty, the mericarps remain enclosed and are not shed easily (Fig. 1 Q), mature mericarp trigonous – globose, 3.0–3.5 × 1.0–2.0 mm, upper side brown and lower side light brown, surface coarsely rugose – tuberculate with irregular lumps and wrinkles, not arranged in regular folds, one mericarp comes out and rest mericarps remain embedded within accrescent calyx, apically two awns, 1.0– 1.5 mm, simple and stellate hairy, divergent or parallel, notch shallow, broad, U-shaped. Seed 2 mm long, subtrigonous, slightly asymmetrical, with unequal side, one angle is broader and more obtuse producing a less regular triangular form, dorsal ridge less sharp, more rounded, glabrous but shortly hairy at the hilum, apex broadly rounded, seed width broader, color uniformly dull brown to grey-brown (Fig. 1 S).

Phylogenetic position.

Morphological analysis shows that the new species is superficially similar to Sida angustifolia. Molecular phylogenetic analyses based on Bayesian inference and maximum likelihood recovered Sida gathwalarum as a distinct and well-resolved lineage within the genus Sida. This new species forms a closely allied clade with Sida acuta, indicating a recent common ancestry; however, it is clearly separated from S. acuta by a distinct branch, reflecting measurable genetic divergence. The clade comprising S. gathwalarum is supported by high posterior probability (100) and bootstrap value (100), reinforcing the robustness of its phylogenetic placement. Importantly, S. gathwalarum does not collapse into S. acuta or any other congeneric species but instead maintains an independent evolutionary lineage within the inferred topology. This molecular distinction is congruent with the observed morphological differences, thereby providing integrative evidence for its recognition as a separate species. Consequently, both molecular and morphological evidence strongly support the taxonomic delimitation of Sida gathwalarum as a new and independent species within Sida sect. Sidae (Fig. 3).

Phenology.

Flowering and fruiting occur almost throughout the year. The flowers open at 11: 00 a. m. during summer and after 12: 00 noon during winter.

Etymology.

The specific epithet gathwalarum honors the Gathwala (Gathwal) Khap, a traditional North Indian community to which the discoverers of this species belong.

Distribution and habitat.

Sida gathwalarum is currently known from several locations in Meerut and Saharanpur, Uttar Pradesh, and Roorkee, Haridwar (Uttarakhand), India (Fig. 3). It grows along open roadsides and wastelands, occurring sympatrically with Sida acuta Burm. f. and Sida rhombifolia subsp. retusa (L.) Borss. Waalk. Other associates of this species are Achyranthes aspera L., Triumfetta rhomboidea Jacq., Urena lobata L., Setaria verticillata (L.) P. Beauv., Cynodon dactylon (L.) Pers., Digitaria ciliaris (Retz.) Koeler, and Oplismenus burmannii (Retz.) P. Beauv.

Systematic position.

Based on molecular phylogenetic analyses, the new species is inferred to be closely allied to Sida acuta, which is a member of Sida sect. Sidae (Sivarajan and Pradeep 1996). Accordingly, the new species is also placed within Sida sect. Sidae.

Additional specimens examined (paratypes).

India • Uttar Pradesh: Saharanpur, Shahpur, 29.758 ° N, 77.657 ° E, 10 December 2025, Inam Malik & Vijai Malik 1707 (WII!); • Uttar Pradesh, Saharanpur, Badoli, 29.917 ° N, 77.656 ° E, 12 December 2025, Inam Malik & Vijai Malik 1708 (WII!).

Conservation status.

Sida gathwalarum is currently documented from a few scattered localities in the Meerut and Saharanpur districts of Uttar Pradesh and Roorkee in the Haridwar district of Uttarakhand, India. The habitats of this species are highly susceptible to anthropogenic disturbances, particularly due to urbanization and developmental works. The species appears to be underreported rather than genuinely rare. It commonly occurs along open roadsides and in wastelands. Based on its apparent distribution and habitat preference, the species is recommended for assignment to the IUCN Red List category Least Concern (LC) (IUCN Standards and Petitions Committee 2024).