A new species of Senecio (Asteraceae, Senecioneae), Senecio anjanericus is described and illustrated from the Anjaneri Hills of Nashik district, Maharashtra, India, based on morphological and cytogenetical studies. The species resembles Senecio bombayensis, but differs from it in small size of the ligules, presence of conspicuous foliose supplementary bracts and dense indumentum on stem. The somatic chromosome number was observed to be 2n = 2x = 20, with all the chromosomes exhibiting median region centromeres. A detailed morphological description, illustration and karyotypic features of the new species are provided.

Taxonomy

The morphological analysis and description of the newly discovered species were made through examination of live specimens in the field as well as in the laboratory. Herbarium specimens housed at BLAT, BSI, CAL, DD and MH were studied. Also, the specimens were compared with the type specimens of closely related species in the virtual herbaria BM, K and E. The acronyms of the herbaria consulted are as per Index Herbariorum (http://sweetgum.nybg.org/science/ih/). Descriptions were made following the terminology of Hickey and King (2001).

Cytogenetics

Mitotic studies on the new species and S. bombayensis were conducted on the root tips obtained from germinating cypselae. Root tips were pre-treated with a saturated solution of para-Dichlorobenzene (pDB) for 4–5 h at 7±2℃. The roots tips were then hydrolysed in 1N HCl and squashed in 2% propionic orcein. Suitable plates from freshly prepared slides were photographed with a Leica DM 750 microscope with attached camera at 1000X magnification. Five cells with well-spread metaphase chromosomes were selected for karyotype analysis by using KaryoMeasure software (Mahmoudi and Mirzaghaderi 2021). Karyological parameters, viz. 2n, mean chromosome length (MCL), total haploid chromosome length (THL), mean centromeric asymmetry (M_CA), coefficient of variation of chromosome length (CV_CL) and coefficient of variation of centromeric index (CV_CI) were used for karyotype analysis. To generate an ideogram with chromosomes with secondary constrictions, a single image was selected for measurement in the idiogram generation option of the software. Voucher specimens were deposited in the Herbarium of Shivaji University, Kolhapur (SUK).