3 urn:lsid:arphahub.com:pub:F7FCE910-8E78-573F-9C77-7788555F8AAD PhytoKeys PK 1314-2011 1314-2003 Pensoft Publishers 10.3897/phytokeys.186.75412 75412 Research Article Lamiaceae Floristics & Distribution Nomenclature Taxonomy Balkans Europe Iberian Peninsula Italy Southern Europe and Mediterranean On the identity of Thymus humifusus var. aureopunctatus (Lamiaceae) and taxonomic notes on the Th. richardii complex Sáez Llorenç https://orcid.org/0000-0003-4551-2432 1 Bogunić Faruk 2 Cambria Salvatore 3 Riera Jesús 4 Bogdanović Sandro sbogdanovic@agr.hr https://orcid.org/0000-0002-1952-6059 5 6 Systematics and Evolution of Vascular Plants (UAB) – Associated Unit to CSIC, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain Universitat Autònoma de Barcelona Barcelona Spain University of Sarajevo, Faculty of Forestry, Zagrebačka 20, 71 000 Sarajevo, Bosnia and Herzegovina University of Sarajevo Sarajevo Bosnia and Herzegovina Department of Biological, Geological and Environmental Sciences, University of Catania, Via A. Longo 19, 95125 Catania, Italy University of Catania Catania Italy Jardín Botánico. Universidad de Valencia. C/ Quart, 80. 46008 Valencia, Spain Universidad de Valencia Valencia Spain University of Zagreb, Faculty of Agriculture, Department of Agricultural Botany, Svetošimunska 25, 10000 Zagreb, Croatia University of Zagreb Zagreb Croatia Centre of Excellence for Biodiversity and Molecular Plant Breeding, Svetošimunska 25, 10000 Zagreb, Croatia Centre of Excellence for Biodiversity and Molecular Plant Breeding Zagreb Croatia

Corresponding author: Sandro Bogdanović (sbogdanovic@agr.hr)

Academic editor: Alan Paton

 2021 09 12 2021 186 139 158 70DC0EB0-3FF3-548A-BBF5-113F5E1EB62B 5787820 17 09 2021 20 11 2021 Llorenç Sáez, Faruk Bogunić, Salvatore Cambria, Jesús Riera, Sandro Bogdanović This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

The name Thymus humifusus var. aureopunctatus, described from Bosnia and Herzegovina, is lectotypified, and its taxonomic value is discussed. Thymus richardii subsp. richardii is currently considered an endemic subspecies common to Mallorca (Balearic Islands) and Bosnia and Herzegovina from the Balkan Peninsula. Specimens identified as Th. richardii from both Balearic Islands and Bosnia and Herzegovina were studied to determine if they are indeed the same taxonomic entity. Detailed micromorphological observations and morphometric analysis, suggest that the Balkan plants (Th. humifusus var. aureopunctatus) and the Majorcan populations (Th. richardii subsp. richardii) are clearly separate entities. For the former name, based on morphological, phytochemical, biogeographical and present results, we propose the subspecific rank, as Th. richardii subsp. aureopunctatuscomb. & stat. nov. Full descriptions of all five subspecies currently accepted within Th. richardii are provided.

 Balkan Peninsula Mediterranean nomenclature original material taxonomy typification Citation

Sáez L, Bogunić F, Cambria S, Riera J, Bogdanović S (2021) On the identity of Thymus humifusus var. aureopunctatus (Lamiaceae) and taxonomic notes on the Th. richardii complex. PhytoKeys 186: 139–158. https://doi.org/10.3897/phytokeys.186.75412

 Introduction

The western Mediterranean Basin is one of the most important regions where the genus Thymus L. has diversified (Morales 1997). Thymus sect. Serpyllum (Mill.) Benth. is a difficult group taxonomically that includes the largest number of species of the genus (Morales 1997). One of the species included in this section is Thymus richardii Pers. a diploid (2n = 28, 30) Mediterranean species with a strongly fragmented distribution (Morales 1997, 2010; Bartolucci 2018; Bartolucci et al. 2018). This species represents an aggregate of allopatric subspecies: Th. richardii subsp. richardii (2n = 28, 30), occurring in Mallorca and Bosnia and Herzegovina (Balkans), Th. richardii subsp. ebusitanus (Font Quer) Jalas, endemic to Ibiza (2n = 30), Th. richardii subsp. vigoi Riera, Güemes & Rosselló, endemic to eastern Spain (Valencia and Alicante provinces) and Th. richardii subsp. nitidus (Guss.) Jalas, endemic of Marettimo Island (Sicily; 2n = 28) (Riera et al. 2007; Morales 2010; Bartolucci et al. 2013; Brullo and Brullo 2020).

As currently circumscribed, Th. richardii subsp. richardii presents a striking distribution pattern, since the isolation between both areas (Mallorca and the Bosnia) is remarkable, and there are no other cases of shared endemism between these areas. Furthermore, i) the differences between the habitat occupied by Th. richardii subsp. richardii in both areas, ii) the differences in the composition of essential oils (Llorens et al. 2014), and iii) the fact that the Bosnian and Herzegovinian population was initially recognised as a separate taxon (Th. humifusus var. aureopunctatus Beck) by several authors (Malý 1908, 1923; Ronniger 1930a, b) invites a re-evaluation of the inclusion of the latter taxon within the synonymy of Th. richardii subsp. richardii as originally proposed by Jalas (1971).

In order to elucidate the taxonomic identity of Th. humifusus var. aureopunctatus, we have sampled specimens from the Bosnian and Herzegovinian and Balearic populations of Th. richardii in the field for a detailed comparison. On the other hand, the morphological characters used to separate the rest of the subspecies recognised in Th. richardii have also been analysed in detail. Finally, a multivariate morphometric analysis based on quantitative traits was carried out to clarify the relationships among taxa within the Th. richardii complex.

 Material and methods Plant material

This study is based on analysis of relevant literature, field surveys and examination of herbarium specimens kept in BC, BCN, COI, HBJS, MA, P, PAL, SARA, VAL, ZA, ZAGR (herbarium codes according to Thiers 2021) and the Herbarium of the Balearic Islands University. For the typification purposes, herbarium specimens deposited at BC, BM, L, P, and PRC were studied using the online herbarium databases or images were requested.

Furthermore, the plant material of recently collected samples of Th. humifusus var. aureopunctatus and Th. richardii subsp. richardii from Bosnia and Herzegovina and Mallorca was analysed, too (Fig. 1A). In total, 61 individuals from seven populations (see Appendix 1) were surveyed for micromorphology and quantitative morphometry.

10.3897/phytokeys.186.75412.figure1 5787822 7A2120C9-AF39-5531-BF9D-CC183D1B35FA

Principal Component Analysis (PCA) of 61 individuals of the Thymus richardii complex A distribution of the studied samples B plot of analysed samples by first and second principal components. C plot of analysed samples by first and third principal components.

https://binary.pensoft.net/fig/620978

Morphological characters recognised as taxonomically discriminant within the Th. richardii complex (Jalas 1972; Morales 2010; and our own observations) were scored either in the field or in the herbarium specimens (Table 1, 3). Morphological observations of materials were carried out under a Zeiss Stemi DV4 binocular stereoscopic microscope. We scored both qualitative and quantitative traits in evaluation of taxa, the latter ones were used to describe the pattern of morphological variation and relationships among taxa.

Descriptive parameters of the analysed traits of the Thymus richardii complex: minimum and maximum values in brackets, mean value with standard deviations and coefficients of variation (%) in brackets.

Trait subsp. richardii subsp. aureopunctatus subsp. ebusitanus subsp. nitidus subsp. vigoi
leaf base cuneate cuneate cuneate cuneate cordate
leaf margin entire entire entire entire denticulate
leaf (blade) length (mm) (7.0–2.03) 9.45 ± 1.40 (14.81) (4.83–7.4) 6.22 ± 0.72 (13.74) (7.0–12.03) 8.62 ± 1.40 (14.80) (6.43–9) 7.66 ±1.05 (13.74) (7.4–9.738.62 ± 1.17 (13.57)
leaf width (mm) (4.3–7.07) 5.52 ± 0.93 (16.85) (3.06–4.93) 3.67 ± 0.59 (15.40) (4.53–6.23) 5.64 ± 0.46 (8.18) (3.1–4.1) 3.67 ±0.43 (11.83) (5.76–7.96) 6.53 ± 1.24 (19.01)
ratio LL/LW (1.21–2.14) 1.73 ± 0.22 (12.96) (1.34–2.01) 1.62 ± 0.17 (10.55) (1.23–1.87) 1.53 ± 0.21 (13.84) (1.98–2.26) 2.11 ± 0.12 (6.13) (1.22–1.51) 1.37 ± 015 (11.72)
longer inflorescence length (mm) (15.0–30.0) 20.71 ± 3.81 (18.39) (8.0–16.0) 11.25 ± 2.35 (20.97) (19–62) 33.66 ± 1.50 (31.20) (22–25.33) 23.33 ± 1.41 (6.06) (15.0–34.0) 23 ± 9.84 (42.82)
pedicel length (mm) (2.97–4.50) 3.58 ± 0.43 (11.95) (1.23–2.1) 1.60 ± 0.23 (14.83) (2.0–3.5) 2.73 ± 0.55 (20.12) (2.23–2.66) 2.40 ± 0.20 (8.37) (3.7–4.66) 4.05 ± 0.53 (13.10)
bract length of larger bracts (mm) (6.40–10.50) 7.80 ± 0.97 (12.44) (3.73–5.83) 4.77 ± 0.45 (9.53) (5.85–9.73) 7.02 ± 0.86 (12.30) (5.73–6.76) 6.23 ± 0.45 (7.30) (6.0–7.33) 6.78 ± 0.69 (10.30)
bracts width of larger bracts (mm) (3.57–7.40) 4.70 ± 0.78 (16.66) (2.2–4.66) 2.97 ± 0.49 (16.64) (3.43–6.93) 4.79 ±0.70 (14.65) (2.76–3.33) 3.03 ± 0.25 (8.26) (2.9–6.5) 5.12 ± 1.94 (37.93)
calyx: stipitate glandular hairs usually absent absent usually abundant abundant few or absent
calyx tube hairiness (eglandular hairs) glabrescent (sometimes glabrous) glabrescent to sparsely hairy densely hairy sparsely hairy sparsely hairy
calyx length (mm) (6.30–7.66) 6.85 ± 0.33 (4.83) (3.5–4.442) 3.99 ± 0.20 (5.03) (4.82–6.36) 5.49 ± 0.40 (7.32) (5.06–5.44) 5.25 ± 0.21 (4.17) (6.5–6.74) 6.58 ± 0.13 (2.02)
upper (middle) calyx teeth length (mm) (1.44–1.98) 1.70 ± 0.19 (10.99) (0.84–1.26) 1.0 ± 0.10 (10.76) (1.04–1.54) 1.21 ± 0.13 (10.76) (1.06–1.12) 1.09 ± 0.02 (2.29) (2.26–2.36) 2.30 ± 0.05 (2.18)
lower calyx teeth length (mm) (2.92–3.58) 3.13 ± 0.15 (4.65) (1.84–2.26) 2.00 ± 0.11 (5.88) (2.26–2.82) 2.59 ± 0.16 (6.28) (2.02–2.54) 2.33 ±0.23 (10.23) (3.24–3.34) 3.29 ± 0.05 (1.52)
length of longer cilia of upper calyx teeth (mm) (0.02–0.14) 0.08 ± 0.04 (45.74) (0.02–0.22) 0.12 ± 0.06 (55.23) (0.52–1.72) 0.68 ± 0.29 (42.65) (0.04–0.28) 0.21 ± 0.11 (54.11) (0.2–0.24) 0.22 ± 0.02 (9.09)
length of longer cilia of lower calyx teeth at middle length (mm) (0.16–0.26) 0.22 ± 0.03 (13.88) (0.34–0.46) 0.39 ± 0.04 (9.74) (0.62–0.84) 0.75 ± 0.05 (7.87) (0.38–0.4) 0.39 ± 0.01 (2.96) (0.38–0.5) 0.46 ± 0.06 (15.06)
calyx tube length (mm) (2.34–3.00) 2.61 ± 0.17 (6.48) (1.42–2.0) 1.61 ± 0.15 (9.88) (2.04–2.5) 2.32 ± 0.12 (5.28) (2.1–2.2) 2.16 ± 0.04 (2.04) (2.5–2.7) 2.59 ± 0.10 (3.88)
length of longer eglandular hair of calyx tube (mm) (0.16–0.26) 0.22 ± 0.03 (13.11) (0.28–0.4) 0.34 ± 0.03 (9.95) (0.6–0.88) 0.74 ± 0.007 (9.90) (0.3–0.38) 0.33 ± 0.03 (10.19) (0.24–0.4) 0.30 ± 0.08 (29.05)

Micromorphology was observed on calyces, which were glued directly to aluminium stubs, coated with 40–50 nm gold, and examined with a scanning electron microscopy (SEM) (Zeiss Merlin FE-SEM) at 5 kV.

 Data analysis

Descriptive statistics (mean, minimum and maximum value, standard deviation and coefficient of variation for each of the studied characters at the taxon level) and univariate statistics (one-way ANOVA followed by Tukey’s test) were calculated to test the significance of differences between taxa within the complex. Overall morphological variation of quantitative traits and relationships of the sampled taxa was evaluated using Principal Component Analysis (PCA). Thymus richardii subsp. vigoi was excluded from analysis due to distinct characters in relation to the other taxa (see Identification key). Means of averaged and standardised values of individuals were used as a matrix data in PCA. PCA was computed on the correlation matrix data of all scored traits. The axes with Eigen values > 1 were used in analysis. PCA computation, descriptive and univariate statistics were run in PAST ver. 3.14 (Hammer 2016).

 Results and discussion

The variation based on SEM micromorphology, univariate and multivariate morphometrics (PCA) of taxa included within Th. richardii complex is described and their taxonomic value of the characters is here discussed.

Variation of individual quantitative morphological traits within the <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Thymus">Th.</tp:taxon-name-part> <tp:taxon-name-part taxon-name-part-type="species" reg="richardii">richardii</tp:taxon-name-part></tp:taxon-name></italic> complex

Mean values of the analysed traits go in favour of morphological differentiation among taxa (Table 1). In general, coefficients of variation (CV) did not exceed 20% (Table 1). The values in Th. richardii subsp. vigoi should be treated with caution because their calculations were based on three individuals. In most cases the coefficients of variation had low (CVs ≤ 10%, 29 cases) and moderate values (CVs from 10 to 20%, 36 cases) (Table 1). High values of coefficients of variation were observed for the trait length of longer cilia of upper calyx teeth (LCU) in each taxon and for the trait longer inflorescence length (IL). The traits calyx length (CL) and calyx tube length (CTL) showed the lowest values of coefficients of variation (Table 1).

One-way ANOVA displayed significant differences between mean values of quantitative traits for all subspecies (p ≤ 0.01). The Tukey’s test revealed significant differences among subspecies for the most of the studied traits (Table 2). The highest number of observed differences was 13 (Th. richardii subsp. ebusitanus vs. Th. humifusus var. aureopunctatus) and 12 (Th. richardii subsp. richardii vs. Th. humifusus var. aureopunctatus and Th. richardii subsp. richardii vs. Th. richardii subsp. nitidus). A considerable level of significant differences (10) was observed between Th. richardii subsp. richardii vs. Th. richardii subsp. ebusitanus and Th. richardii subsp. ebusitanus vs. Th. richardii subsp. nitidus (9). The smallest number of significant differences (7) was evidenced between Sicilian population of Th. richardii subsp. nitidus and the Balkan Th. humifusus var. aureopunctatus (Table 2).

The studied traits differentiating between taxa based on result of the Tukey’s t tests (p = 0.01) (abbreviations are as in Table 3).

Taxon richardii ebusitanus aureopunctatus
ebusitanus LL/LW, IL, PL, BL, CL, UTL, LTL, LCU, LCL, CTL, LEH
aureopunctatus LL, LW, IL, PL, BL, BW, CL, UTL, LTL, LCU, LCL, CTL, LEH LL, LW, IL, PL, BL, BW, CL, UTL, LTL, LCU, LCL, CTL, LEH
nitidus LL, LW, LL/LW, PL BL, BW, CL, UTL, LTL, LCL, CTL, LEH LW, LL/LW, BW, CL, LTL, LCU, LCL, CTL, LEH LL/LW, IL, PL, BL, CL, LTL, CTL
Morphometric relationships among taxa within the <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Thymus">Th.</tp:taxon-name-part> <tp:taxon-name-part taxon-name-part-type="species" reg="richardii">richardii</tp:taxon-name-part></tp:taxon-name></italic> complex

Morphological variation was explained by three principal components with Eigen values > 1 which clearly separated four morphological clusters corresponding to Th. richardii subsp. richardii, Th. humifusus var. aureopunctatus, Th. richardii subsp. ebusitanus and Th. richardii subsp. nitidus (Table 3, Fig. 1B, C). The first three components accounted for 90.3% of the total variance (PC1 = 57.6%, PC2 = 23.9% and PC3 = 8.8%). The taxa were separated mostly along the first and second axis (Fig. 1B). Thymus richardii subsp. nitidus was a neighbouring group to Th. humifusus var. aureopunctatus. A plot onto PC 1 and PC 3 revealed that Th. richardii subsp. nitidus also represented a distinct cluster within the complex (Fig. 1C). Following characters (CL, LTL, CTL, and BL) with moderate coefficients of correlations were associated with PC1 (Table 3). The characters LEH, LCL and LCU contributed to the PC2. The highest correlations with the PC3 showed derived trait L/W and leaf width (LW) which contributed to the separation of Th. richardii subsp. nitidus (Table 3). Principal component analysis of quantitative morphological data demonstrates that allopatric populations of the Th. richardii complex are clearly distinguishable according to their taxonomic affiliation.

Principal components revealed by the PCA for the Thymus richardii complex.

Trait Component
PC 1 PC 2 PC 3
LL leaf (blade) length 0.307 0.032 0.143
LW leaf (blade) width 0.275 0.181 -0.372
L/W ratio L/W 0.032 -0.241 0.818
IL longer inflorescence length 0.246 0.311 0.157
PL pedicel length 0.321 -0.023 0.088
BL bract length of larger bracts 0.332 0.036 0.059
BW bracts width of larger bracts 0.296 0.163 -0.178
CL calyx length 0.347 -0.062 0.043
UTL upper (middle) calyx teeth length 0.316 -0.167 -0.094
LTL lower calyx teeth length 0.339 -0.067 0.033
LCU length of longer cilia of upper calyx teeth 0.002 0.472 0.250
LCL length of longer cilia of lower calyx teeth at middle length -0.108 0.502 0.117
CTL calyx tube length 0.338 -0.029 0.064
LEH length of longer eglandular hair of calyx tube -0.072 0.519 0.098
Eigenvalue 7.990 3.353 1.132
Contribution 0.576 0.239 0.088
Cumulative (%) 0.576 0.815 0.903

Variation in particular morphological traits indicated a similar pattern observed in PCA, confirming a high level of morphological differentiation between the studied taxa. High levels of both morphological and genetic differentiation within plant complexes are not surprising in the Mediterranean. This pattern of variation, which often results in endemism, is particularly pronounced for populations inhabiting the Mediterranean islands (Thompson 2020). Due to different geological and biogeographical processes, long-term isolation, adaptation and specialization to contrasting habitats, the ancestral populations of Th. richardii diverged into distinct entities across the Mediterranean and the Balkans.

 General habit

All the taxa included within the Thymus richardii complex are woody perennials with young or flowering stems with hairs on all faces, more or less evenly distributed. These hairs are eglandular, usually retrorse, up to 0.2 mm long (0.4 mm long in Th. richardii subsp. ebusitanus), intermixed with sessile glands. According to Morales (2010), the plant length separates the populations from Mallorca from those of Ibiza (7–13 cm vs. 10–24 cm, respectively), but in our opinion this character is rather variable and has no taxonomic significance. We have collected Majorcan plants of Th. richardii subsp. richardii that measure up to 40 cm in length.

 Leaves

All the studied taxa have flat leaves, not ciliate at base, with entire margins, except in Th. richardii subsp. vigoi, which has denticulate leaves. On the basis of leaf morphology (Riera et al. 2007) Th. richardii subsp. vigoi is easily separable from the rest of the members of the Th. richardii complex. Leaves shape varies from ovate to elliptical. Jalas (1972) attributed to Th. richardii subsp. nitidus leaves more than twice as long as wide. Certainly Th. richardii subsp. nitidus usually has leaves with a higher length / width ratio than the rest of the taxa (Table 1), but we have studied plants of the island of Marettimo with leaves less than twice as long as wide. On the other hand, some Majorcan specimens of Th. richardii subsp. richardii have leaves more than twice as long as wide.

The leaves have spheroidal yellowish-reddish glands, and sometimes scattered hairs exist in several taxa of this complex. Some specimens of Th. richardii subsp. ebusitanus, Th. richardii subsp. vigoi and Th. richardii subsp. nitidus have a hairy main midrib in its basal half; this hairiness sometimes extending towards adjacent areas of the blade. Nevertheless, this character seems not to be sufficiently constant for taxonomic purposes.

 Inflorescence

Flowers are arranged in distinct inflorescences, usually capitate to more or less elongate (up to 62 mm long in Th. richardii subsp. ebusitanus, Table 1). Bracts are similar to leaves, but smaller, and the bracteoles linear to linear-lanceolate. Pedicels are somewhat longer than documented for the species (Morales 2010), since in Majorcan plants of Th. richardii subsp. richardii can reach up to 5 mm long.

 Calyx

Upper calyx-teeth are conspicuously different from lower. The upper lip teeth are usually narrower in Th. richardii subsp. vigoi. The calyx is green to purplish-green or to purple-violet. This colour variation can be observed within the same population, and the purplish coloration usually occurs in specimens that grow in more exposed places.

Regarding the calyx length, Th. humifusus var. aureopunctatus shows the lowest values, whereas the longest are those of the Majorcan populations of Th. richardii subsp. richardii (Table 1; Fig. 2). On the other hand, the length of the lower teeth of the calyx also allows separating the previous taxa (Table 1, 2). The presence of shorter calyces in Th. humifusus var. aureopunctatus was documented by Morales (2010), but so far this variation had not been quantified. From our point of view, the calyx length is a diagnostic character to separate the Balkan and the Balearic populations, together with other morphological characters (Table 1, 2).

10.3897/phytokeys.186.75412.figure2 5787824 FA26498B-8DD9-5DE1-811C-9BE0BE709F16

Calyx morphology for Thymus richardii and Th. humifusus var. aureopunctatus. For each taxon lateral (left) and ventral (right) views are shown. Thymus richardii subsp. richardii (A, B Spain, Mallorca); Th. humifusus var. aureopunctatus (C, D Bosnia and Herzegovina, Dužani); Th. richardii subsp. ebusitanus (E, F Eivissa, Ses Balandres); Th. richardii subsp. nitidus (G, H Sicily, Marettimo); Th. richardii subsp. vigoi (I, J Spain, Valencia, La Safor). Scale: 200 micrometres.

https://binary.pensoft.net/fig/620979

The calyces are more or less hairy, with spheroidal yellowish-reddish glands. Our results show that the characters related to the hairiness of the calyx have taxonomic relevance in the Th. richardii complex. Calyx indumentum in Th. richardii subsp. ebusitanus is dense, with long eglandular hairs (up to 1 mm long), mainly on the margins of the lower teeth of the calyx and the ventral part of the calyx tube (Figs 2, 3). On the contrary, the calyx in the Majorcan populations of Th. richardii subsp. richardii is glabrescent (the upper lip and the dorsal surface of the calyx tube are glabrous or glabrescent) and the hairs are much shorter (Table 1). Thymus humifusus var. aureopunctatus has glabrescent to sparsely hairy calyces, but the eglandular hairs are usually more abundant and longer than in the Majorcan plants of Th. richardii subsp. richardii.

10.3897/phytokeys.186.75412.figure3 5787826 659B07CD-2B56-56E4-AE04-E2C7281BCF2D

Detail of lower teeth and tube of the calyx and detail of glandular hairs of calyx tube in Thymus richardii subsp. richardii (A, F Spain, Mallorca, Puig Major, Es Bufador); Th. humifusus var. aureopunctatus (B, G Bosnia and Herzegovina, Dužani); Th. richardii subsp. ebusitanus (C, H, L Balearic Island, Eivissa); Th. richardii subsp. nitidus (D, J, K Italy, Sicily, Marettimo); Th. richardii subsp. vigoi (E, I Spain, Valencia, La Safor). Scales: 200 micrometers (A–J); 20 micrometers (K–L).

https://binary.pensoft.net/fig/620980

Stipitate glandular hairs are found in calyces (tube, teeth and even on the adaxial surface of upper teeth) of several taxa (Table 1). As noted by Jalas (1972) these glandular hairs are particularly abundant in Th. richardii subsp. nitidus (Figs 2, 3). However, stipitate glandular hairs are also usually found (in variable density) in Th. richardii subsp. ebusitanus, while in Majorca the specimens having these glandular hairs are rather rare but are observed on specimens from Coma de n’Arbona (BC 651145). These glandular hairs were not documented for Balearic plants of Th. richardii by Morales (2010). This character seems to be variable in the Balearic populations, since in the same locality there are plants without these glandular hairs.

 Corolla

The upper lip is emarginate and the lower has 3 subequal lobes (middle lobe somewhat longer). The corolla is more or less hairy on the outer surface, with spheroidal yellowish-reddish glands. Its colour varies from pale rose (sometimes whitish or cream in Th. richardii subsp. vigoi) to pinkish-purple. The coloration is somewhat variable within the different taxa and in our opinion has no taxonomic significance.

 Taxonomic treatment

The Majorcan and the Balkan populations, which were included within typical T. richardii (Jalas 1971, 1972; Morales 2010) are morphologically distinct; they differ in several characters including calyx size, lower calyx teeth length, length of hairs on the calyx tube, length of pectinate hairs of lower calyx teeth and indumentum density on the calyx (Figs 1–3; Table 1, 3). The Majorcan plants have, compared to those from Bosnia and Herzegovina, longer and less hairy calyces, with shorter hairs and longer lower calyx teeth with shorter (and less dense) pectinate hairs. Examination of herbarium specimens from five populations (16 specimens from Mallorca, 21 from Bosnia and Herzegovina) plus other specimens (see additional specimens examined) revealed that the diagnostic characters are constant within each geographic group. The morphological and biochemical (Llorens et al. 2014) differentiation between the Majorcan and the Balkan populations and their allopatric distribution (they are separated by a gap of ca. 1.300 km) firmly support the recognition of two subspecies, since the level of morphological differentiation between the two taxa does not meet the criteria commonly used to delimit species in Thymus. Certainly, further research using molecular markers is needed to reveal genetic relationships and biogeographic history of the Th. richardii complex.

Plantae Lamiales Lamiaceae 8DECCD33-118D-5BEB-9A36-0BC03E884E09 Thymus richardii subsp. richardii Pers., Syn. Pl. 2: 130. 1806 ≡ Thymus serpyllum var. richardii (Pers.) Knoche, Fl. Balear. 2: 354. 1922. ≡ Th. serpyllum subsp. richardii (Pers.) Malag., H. Bianor, Educador Botánico Baleares: 150. 1971. Type.

Holotype (see Rosselló and Sáez 2001: 109): P-Lamarck.

 Description.

Stems up to 47 cm long, procumbent to reptant. Leaf blade up to 13 × 7.7 mm, broadly ovate to elliptical, entire. Inflorescence 15–30 mm long, capitate to oblong; bracts up to 11 × 7.8 mm, similar to leaves, entire, glabrous. Calyx 6–8 mm long, glabrescent (sometimes glabrous), with eglandular hairs up to 0.3 mm long, occasionally with scattered stipitate glandular hairs; calyx tube 2.2–3.2 mm long, glabrescent (sometimes glabrous on the dorsal surface), with eglandular hairs up to 0.3 mm long on the ventral surface; central tooth of upper lip 1.3–2.2 mm long, lower teeth 2.8–3.8 mm long, with pectinate hairs up to 0.3 mm long. Corolla 7–11 mm long, rose to pinkish-purple (Fig. 4, C, E).

10.3897/phytokeys.186.75412.figure4 5787828 FA676E50-1AC7-507C-B4F9-7C27977B68C0

Habit and detail of the inflorescence of Thymus humifusus var. aureopunctatusA, D from Bosnia and Herzegovina, Dužani, 3 July 2020; B from Bosnia and Herzegovina Džepi, 10 July 2020 (photo F. Bogunić), and of Th. richardii subsp. richardiiC, E from Spain, Balearic Islands, Mallorca, Coma de N’Arbona, 17 June 2021 (photo L. Sáez).

https://binary.pensoft.net/fig/620981 Chromosome number.

2n = 30 (Morales 1995).

 Distribution.

Endemic to Mallorca, Eastern Balearic Islands (Spain).

 Habitat.

Cliffs, on humid and north-facing limestone rocks, 250–1430 m a.s.l.

 Remarks.

This is a rare plant, documented from three localities in the north of Mallorca (Ternelles mountain, Formentor peninsula and Puig Major) of which we have only been able to verify its presence in the last locality, growing on cliffs with very difficult access. This taxon could be facing a population decline. Bianor (1917) at the beginning of the 20th century, considered it as abundant in the Puig Major [“Abondant dans les endroits peu accessibles”]. In fact, there are dozens of specimens from this mountain and which are preserved in various herbaria; mostly collected in the late 19th and early 20th centuries. Currently, Th. richardii subsp. richardii is very scarce at the same locality where it was reported by Bianor (1917) and the plants are practically inaccessible if climbing techniques are not used. Another population located on a different slope of the same massif is also scarce and very difficult to access. This possible population decline could be due to a loss of potential habitat and intense predation by feral goats (Capra hircus).

 Specimens examined.

Spain. Balearic Islands, Mallorca: Comma de n’Arbona, Puig Major, 12 June 1852, G. Vigineix (P 04436032, P 04436034); Majorque, 19 June 1869, Bourgeau (P 04436046); rochers des Arbonas [n’Arbona], 17 Apr 1870, F. Barceló (COI 00045051, P 03389631); Coma de n’Arbona et Puig Major de Son Torrella, 1000–1300 m, 24 June 1885 and 29 July 1885, Porta & Rigo (P 04436045); Mallorca: Coma de n’Arbona, Sóller, 30 June 1879, A. Crespí (BC 651145, P 04407218); Puig Major, 1000–1400 m, 12 July 1917, F. Bianor (BC 50119); Féntes des rochers, Puig Major, 1000–1450 m, 12 July 1918, F. Bianor (BC 50118); Puig Major, Féntes des rochers, 1000–1500 m, 7 July 1919, F. Bianor, Pl. Espagne F. Sennen 3768 (BC 50123); Coma de n’Arbona, 18 June 1920, Gros (BC 859198, P 04407218); Coma de n’Arbona, 4 July, 1936, Kennedy 48 (BC 103732); Sóller, escletxes dels espadats de la Coma de n’Arbona, July, 1958, L. Garcías Font (BC 145169); Puig Major, Coma de n’Arbona, 27 June 1985, T. Rabassa (HBJS 5700); Puig Major, Escorca, 10 July 1986, L. Sáez (MA 592837); Puig Major de Son Torrella, c. via des Bufador, Escorca, 31SDE8207, 1200 m, 14 June 2006, L.G. Valle & L. Sáez LS-6445 (L. Sáez, herb. pers.); Escorca, Puig Major, Penyal des Bufador, 31DE8206, 1340 m, 30 June 2020, L. Sáez (L. Sáez, herb. pers.); Fornalutx, Coma N’Arbona, 31SDE8105, 1100 m, 17 June 2021, L. Sáez (L. Sáez, herb. pers.).

 Plantae Lamiales Lamiaceae 489497C3-18E2-5994-AEC9-8FDF11379162 Thymus richardii subsp. aureopunctatus urn:lsid:ipni.org:names:77234197-1 (Beck) L.Sáez, Bogunić & Bogdanović, comb. & stat. nov. ≡ Thymus humifusus var. aureopunctatus Beck, Ann. Naturhist. Mus. Wien 2: 142. 1887, basionym. ≡ Th. aureopunctatus (Beck) K. Malý, Prilozi za floru Bosne i Herzegovine: 557. 1908. Type.

Herc. [Herzegovina], Nächst Konjica, 8 July 1885, G. Beck (lectotype: PRC 455886! designated here, Fig. 5).

 Description.

Stems up to 45 cm long, procumbent to reptant. Leaf blade up to 7.7 × 5.3 mm, suborbicular to elliptical, entire. Inflorescence 8–21 mm long, capitate; bracts up to 6.5 × 5 mm, similar to leaves, entire, usually hairy at margin (eglandular hairs up to 1 mm long). Calyx 3–5 mm long, glabrescent to sparsely hairy, with eglandular hairs up to 0.5 mm long, without stipitate glandular hairs; calyx tube 1.3–2.2 mm long, sparsely hairy, with eglandular hairs up to 0.5 mm long on the ventral surface; central tooth of upper lip 0.7–1.6 mm long, lower teeth 2–3 mm long, with hairs pectinate up to 0.5 mm long. Corolla 6–9 mm long, rose (Fig. 4, A, B, D).

 Chromosome number.

2n = 28 (Kaleva 1969).

 Distribution.

Endemic to surroundings of Konjic (Podorašac, Koznik, Dužani, Dudle, Džepi, Zlatar, Borci, Spiljani, Glavatičevo, Pribilja, Repovica), northern Herzegovina. The taxon covers an area of c. 280 km2.

 Habitat.

Sandy dolomites and dolomitic rocky places, 400–1040 m a.s.l.

 Remarks.

Beck (1887) described Th. humifusus var. aureopunctatus from “In saxosis prope Konjicam” [Bosnia and Herzegovina] and related this new variety to Thymus humifusus Bernh. ex Link, which is currently regarded a synonym of the tetraploid Th. praecox Opiz (Jalas 1971; Euro+Med 2006; Plant List 2021; WFO 2021). Günther Beck (1856–1931) was a Bohemian botanist, and his herbarium is currently kept at PRC and W (Stafleu and Cowan 1976). We have been able to locate original material of Th. humifusus var. aureopunctatus at PRC. This is a well-prepared specimen; it matches the description and the provenance indicated in the protologue. Therefore, we designate the specimen with barcode PRC 455886 as the lectotype of the name Th. humifusus var. aureopunctatus (Fig. 5). The taxon occurs in fragmented subpopulations in Bosnia and Herzegovina. Their habitats are threatened by forest succession and canopy closure, but frequent fire incidences represent the most serious threat to its subpopulations. However, the overall population trend of Th. richardii subsp. aureopunctatus is inferred to be generally stable (F. Bogunić, pers. observ.).

10.3897/phytokeys.186.75412.figure5 5787830 3F82635D-422E-58D3-B3EA-90C7C71C9ED6

Lectotype of Thymus humifusus var. aureopunctatus (PRC 455886).

https://binary.pensoft.net/fig/620982 Specimens examined.

Bosnia and Herzegovina. Konjic, 8 July 1885, G. Beck (PRC 455886!, lectoptype); Konjic, Dužani, 43.509894N 18.152114E, 830 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.); Konjic, Džepi, 43.675506N 18.011992E 757 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.); Bosnia and Herzegovina, Dudle, 43.540567N 18.121261E, 1034 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.); Flora Herzegovinae. In pineti (Pinus nigra) inter Pričepa-Bigolje; solo dolomitico, 720 m, 9 August 1908, K. Maly (ZA); Flora Hercegovinae. In saxosis dolomiticis ad Repovica prope Konjic, 12 July 1931, V. Loschingg (ZA).

 Plantae Lamiales Lamiaceae 2A0D0D53-1113-5CC8-A0B3-1705A7C52B0C Thymus richardii subsp. ebusitanus (Font Quer) Jalas, Bot. J. Linn. Soc. 64(3): 264. 1971 ≡ Thymus richardii var. ebusitanus Font Quer, Cavanillesia 7: 77. 1935; ≡ Th. ebusitanus (Font Quer) Romo, Fl. Silvestres Baleares: 266. 1994. Type.

Eivissa, cala de les Torretes, 29 May 1918, Font Quer & Gros (lectotype: BC 50117! designated by Jalas 1971: 264).

 Description.

Stems up to 54 cm long, more or less reptant to suberect. Leaf blade up to 11 × 8 mm, suborbicular to elliptical, entire. Inflorescence 19–62 mm long, oblong; bracts up to 8.3 × 7.3 mm, similar to leaves, entire; glabrous to hairy at margin and midrib (eglandular hairs up to 1 mm long). Calyx 4.5–6.9 mm long, densely hairy, sometimes hirsute, with eglandular hairs up to 1 mm long, usually with stipitate glandular hairs; calyx tube 1.8–2.7 mm long, densely hairy, with eglandular hairs up to 1 mm long on the ventral surface; central tooth of upper lip 0.9–1.9 mm long, lower teeth 1.9–3.1 mm long, with pectinate hairs up to 1 mm long. Corolla 6–8.5 mm long, pale rose.

 Chromosome number.

2n = 30 (Morales 1990).

 Distribution.

Endemic to northern Eivissa, Western Balearic Islands (Spain).

 Habitat.

Limestone rocky places, 5–370 m a.s.l.

 Specimens examined.

Spain. Balearic Islands, Eivissa: cala de les Torretes, 29 May 1918, Font Quer & Gros (BC 50117, lectotype); Santa Agnès, a la Cala de les Torretes, 15 June 1918, Gros (BC 50116); Cala de’n Damià, 10 July 1920, Gros (BC 858975, P 04438273); cala de les Torretes, 8 July 1920, Gros (BC 859210, P 04438274); cala de Santa Agnès, 5 m, July 1935, Gros (BC 87078, BC87079); Cala Aubarca, 1 Aug 1974, J.Y. Lesouëf (MA 620032); vicum Sant Mateu, cala d’Aubarca, 31SCD52, 50 m, 23 June 1979, Fernández Casas 2883 (BC 633215); Cala den Sardina, 2 June 1981, Cardona & al. (BC 644574); Cala den Sardina, 20 June 1983, L. Llorens (Herb. Univ. Illes Balears); cingles d’en Recó, 8 June 1997, N. Torres, M. Mayol & L. Sáez (MA 592780); Ses Balandres, 31SCD5523, 131 m, 3 June 2010, C. Benedí & L. Sáez (L. Sáez, herb. pers.).

 Plantae Lamiales Lamiaceae 8108DAB1-BEB2-5D36-B6F7-2521E8F08340 Thymus richardii subsp. nitidus (Guss.) Jalas, Bot. J. Linn. Soc. 64: 264. 1971 ≡ Thymus nitidus Guss., Fl. Sicul. Syn. 2(1): 97. 1844; ≡ Th. serpyllum var. nitidus (Guss.) Bég. in Fiori & Béguinot, Fl. Italia 3: 66. 1903. - Th. sensu lucidus Guss., Fl. Sicul. Prodr., Suppl.: 198. 1843 Type.

Marettimo, 10 May 1829, Herb. Gussone Sicilia s.c., bottom-right specimen (Lectotype: NAP-Gussone!, designated by Bartolucci et al. 2013: 1310).

 Description.

Stems up to 25 cm long, procumbent or suberect. Leaf blade up to 10 × 4.5 mm, elliptical, entire. Inflorescence 8–30 mm long, subcapitate to oblong; bracts up to 7 × 4 mm, similar to leaves, entire, glabrous to hairy at margin and midrib (eglandular hairs up to 0.4 mm long, mixed with stipitate glandular hairs). Calyx 4.5–6.3 mm long, densely covered by stipitate glandular hairs and sparse eglandular hairs up to 0.5 mm long; calyx tube 1.9–2.5 mm long, with eglandular hairs up to 0.5 mm long on the ventral surface; central tooth of upper lip 0.8–1.5 mm long, lower teeth 2–3 mm long, with pectinate hairs up to 0.5 mm long. Corolla 6.5–9.5 mm long, pale rose.

 Chromosome number.

2n = 28 (Morales 1997)

 Distribution.

Endemic to Island of Marettimo, Sicily (Italy).

 Habitat.

Limestone rocky places, 10–600 m a.s.l.

 Specimens examined.

Italy. Sicily, Marettimo, sine leg. (PAL); Isola di Marettimo, rupi di P. Anzine, 21 July 2007, Scuderi (VAL 184304).

 Plantae Lamiales Lamiaceae 0D988EF0-69CF-5B18-96B2-A0B427C1A8C1 Thymus richardii subsp. vigoi Riera, Güemes & Rosselló, Fl. Montiber. 37: 78. 2007 Type. Spain, Valencia, Villalonga, La Safor, ad l’Orxa, 30SYJ3706, 600 m, 4 July 2000, J. Riera & J. Güemes (holotype: VAL 185406!; isotype: MA 757804!; Riera et al. 2007). = Thymus richardii var. valentinus O. Bolòs & Vigo, Collect. Bot. (Barcelona) 14: 95. 1983 Type.

Spain, Valencia province, Valentia, c. Gandia, 15 Sept 1950, P. Cañigueral (holotype: BC 119858!; Bolòs and Vigo 1983).

 Description.

Stems up to 16 cm long, suberect to erect. Leaf blade up to 11 × 8.1 mm, ovate-triangular, denticulate. Inflorescence 15–34 mm long, usually oblong; bracts up to 8 × 7 mm, similar to leaves, denticulate, usually glabrous. Calyx 5.8–7 mm long, sparsely hairy, with eglandular hairs up to 0.7 mm long, sometimes with sparse stipitate glandular hairs; calyx tube 2.1–2.9 mm long, with eglandular hairs up to 0.5 mm long on the ventral surface; central tooth of upper lip 1.8–2.6 mm long, lower teeth 3–3.5 mm long, with pectinate hairs up to 0.7 mm long. Corolla 7–10 mm long, whitish to pale rose, sometimes cream.

 Chromosome number.

Unknown.

 Distribution.

Endemic to Alicante and Valencia provinces (Spain).

 Habitat.

Open scrub, on limestone soil, 130–600 m a.s.l.

 Remarks.

Plants which were considered to be hybrids between Th. richardii subsp. vigoi and T. piperella L. have been called T. × bolosii. The hybrid has been reported from a small area of Serra de la Safor, eastern Spain (Riera et al. 2020).

 Specimens examined.

Spain. Alicante province: La Vilallonga, La Safor, 136 m, 22 June 1984, J.B. Peris & G. Stübing (BC 674556); Valencia province, Valentia, c. Gandia, 15 Sept 1950, P. Cañigueral (BC 119858); Villalonga, La Safor, ad l’Orxa, 30SYJ3706, 600 m, 4 July 2000, J. Riera & J. Güemes (VAL 185406!).

 Identification key for <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Thymus">Thymus</tp:taxon-name-part> <tp:taxon-name-part taxon-name-part-type="species" reg="richardii">richardii</tp:taxon-name-part></tp:taxon-name></italic> complex

We propose the following key for the subspecies of the Thymus richardii complex in order to include the new proposed subspecies.

1 Leaves denticulate, cordate at base subsp. vigoi
– Leaves entire (rarely slightly denticulate) cuneate at base 2
2 Calyx glabrescent (sometimes glabrous) to sparsely hairy; glandular hairs usually scarce or absent 3
– Calyx hairy to densely hairy; glandular hairs usually present 4
3 Calyx 3–5 mm long subsp. aureopunctatus
– Calyx 6–8 mm long subsp. richardii
4 Calyx with abundant eglandular hairs, usually with sparse to dense glandular stipitate hairs; lower calyx teeth with pectinate pluricellular eglandular hairs up to 1 mm long subsp. ebusitanus
– Calyx densely covered by glandular hairs, mixed with sparse eglandular hairs; calyx teeth with pectinate eglandular pluricellular hairs up to 0.5 mm long subsp. nitidus
Acknowledgements

We thank Patrik Mráz (Herbarium PRC, Charles University) for his valuable help in the study of the herbarium material of Thymus humifusus var. aureopunctatus. Faruk Bogunić was supported by the Environmental Fund of the Federation Bosnia and Herzegovina (grant no. 01-09-1581/2017) and Sandro Bogdanović was supported by the grant of the University of Zagreb.

 References BartolucciF (2018) Thymus L. In: PignattiSGuarinoRLa RosaM (Eds) Flora d’Italia.Ed. 2, Vol. 3. Edagricole, Bologna, 278–290. BartolucciFPeruzziLPassalacquaN (2013) Typification of names and taxonomic notes within the genus Thymus L. (Lamiaceae).Taxon62(6): 1308–1314. https://doi.org/10.12705/626.1 BartolucciFPeruzziLGalassoGAlbanoAAlessandriniAArdenghiNMGAstutiGBacchettaGBallelliSBanfiEBarberisGBernardoLBouvetDBovioMCecchiLDi PietroRDominaGFascettiSFenuGFestiFFoggiBGalloLGottschlichGGubelliniLIamonicoDIberiteMJiménez-MejíasPLattanziEMarchettiDMartinettoEMasinRRMedagliPPassalacquaNGPecceniniSPennesiRPieriniBPoldiniLProsserFRaimondoFMRoma-MarzioFRosatiLSantangeloAScoppolaAScortegagnaSSelvaggiASelviFSoldanoAStincaAWagensommerRPWilhalmTContiF (2018) An updated checklist of the vascular flora native to Italy.Plant Biosystems152(2): 179–303. https://doi.org/10.1080/11263504.2017.1419996 BeckG (1887) Flora von SüdBosnien un der angrenzenden Hercegovina.Annalen des Naturhistorischen Museums in Wien2: 81–184. BianorF (1917) Plantes de Mallorca.Butlletí de la Institució Catalana d’Història Natural17: 133–152. BolòsOVigoJ (1983) Notes sobre taxonomia i nomenclatura de les plantes, II.Collectanea Botanica (Barcelona)14: 89–103. BrulloCBrulloS (2020) Flora endemica illustrata della Sicilia. Laruffa Editore, 1–441. https://doi.org/10.1007/978-3-030-34525-9_1 Euro+Med (2006) Euro+Med PlantBase - the information resource for Euro-Mediterranean plant diversity. Published on the Internet http://ww2.bgbm.org/EuroPlusMed/ [accessed 10 July 2021] HammerØ (2016) PAST:3.12. Natural History Museum, University of Oslo. Available at: http://folk.uio.no/ohammer/past/ [accessed 2 February 2020] JalasJ (1971) Notes on Thymus L. (Labiatae) in Europe. 11. Comments on species and subspecies. In: HeywoodVH (Ed.) Flora Europaea Notulae Systematicae ad Floram Europaeam spectantes No. 10.Botanical Journal of the Linnean Society64: 247–271. https://doi.org/10.1111/j.1095-8339.1971.tb02147.x JalasJ (1972) Thymus L. In: TutinTGHeywoodVHBurgesNAMooreDMValentineDHWaltersSMWebbDA (Eds) Flora Europaea 3.Cambridge University Press, Cambridge, 172–182. KalevaK (1969) Chromosome counts on Thymus L. (Labiatae).Annales Botanici Fennici6: 344–347. LlorensLLlorens-MolinaJAAgnelloSBoiraH (2014) Geographical and environment-related variations of essential oils in isolated populations of Thymus richardii Pers. in the Mediterranean basin.Biochemical Systematics and Ecology56: 246–254. https://doi.org/10.1016/j.bse.2014.05.007 MalýK (1908) Prilozi za floru Bosne i Hercegovine 1.Glasnik Zemaljskog muzeja u Bosni i Hercegovini20(4): 557–567. MalýK (1923) Prilozi za floru Bosne i Hercegovine 9.Glasnik Zemaljskog muzeja u Bosni i Hercegovini35: 141–149. MoralesR (1990) Números cromosomáticos de plantas occidentales, 582–590.Anales del Jardin Botanico de Madrid47(1): 193–198. MoralesR (1995) Números cromosómicos para la flora española, 764–768.Lagascalia17(2): 388–391. MoralesR (1997) Synopsis of the genus Thymus L. in the Mediterranean area.Lagascalia19(1–2): 249–262. MoralesR (2010) Thymus L. In: MoralesRQuintanarACabezasFPujadasAJCirujanoS (Eds) Flora Iberica vol.XII. Verbenaceae-Labiatae-Callitrichaceae. Real Jardín Botánico de Madrid, Madrid, 349–409. Plant List (2021) The Plant List. http://www.theplantlist.org/ [accessed 10 July 2021] RieraJGuemesJRossellóJA (2007) Thymus richardii (Lamiaceae) in the Iberian Peninsula.Flora Montibérica37: 77–80. RieraJGuemesJRossellóJA (2020) Thymus × bolosii (Lamiaceae) a new wild hybrid from the eastern Iberian Peninsula.Flora Montibérica78: 77–80. RonnigerK (1930a) Thymus L. In: HayekA (Ed.) Prodromus Florae Peninsulae Balcanicae 2.Feddes Reppertorium, Beih, 337–382. RonnigerK (1930b) Zwei neue Pflanzenformen aus Siideuropa. Feddes Repertorium 28(S1): 67–69. https://doi.org/10.1002/fedr.4870282108 RossellóJASáezL (2001) Index Balearicum. An annotated check-list of the vascular plants described from the Balearic Islands.Collectanea Botanica (Barcelona)25(1): 1–192. https://doi.org/10.3989/collectbot.2000.V25.42 StafleuFACowanRS (1976) Taxonomic literature: a selective guide to botanical publications and collections with dates, commentaries and types 1. Ed. 2. Bohn, Scheltema & Holkema, Utrecht, 1–1136. https://doi.org/10.5962/bhl.title.48631 ThiersB (2021) Index Herbariorum: a global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. http://sweetgum.nybg.org/science/ih/ [accessed on 10 July 2021] ThompsonJD (2020) Plant evolution in the Mediterranean – insights for conservation. 2nd edition, Oxford University Press, 1–352. https://doi.org/10.1093/oso/9780198835141.001.0001 WFO (2021) World Flora Online. Published on the Internet. http://www.worldfloraonline.org. [accessed on 10 July 2021] Appendix I. List of specimens included in morphometric analyses.

Thymus richardii subsp. richardii. Spain. Mallorca: Coma de n’Arbona, Sóller, 30 June 1879, A. Crespí (BC 651145) [1 specimen]; Fentes des rochers, 1000–1150 m, 12 July 1918, Bianor (BC 50118) [1 specimen]; Ibidem 7 July, 1919, Bianor (BC 50123) [1 specimen]; Ibidem 12 July, 1917, Bianor (BC 50119) [1 specimen]; Coma de n’Arbona, 18 June 1920, Gros (BC 859198) [1 specimen]; Col de n’Arbona, 4 July, 1936, Kennedy 48 (BC 103732) [1 specimen]; Espadats de la coma de n’Arbona, July, 1958, Garcias Font (BC 145169) [1 specimen]; Coma de n’Arbona, 27 June 1985, T. Rabassa (HBJS 5700) [1 specimen]; Coma N’Arbona, 31SDE8105, 1100 m, 17 June 2021, L. Sáez (L. Sáez, herb. pers.) [4 specimens]. Puig Major, via des Bufador, Escorca, 31SDE8207, 1200 m, 14 June 2006, L.G. Valle & L. Sáez LS-6445 (L. Sáez, herb. pers.) [1 specimen]; Puig Major, Penyal des Bufador, 31DE8206, 1330–1350 m, 30 June 2020, L. Sáez (L. Sáez, herb. pers.) [8 specimens].

Thymus richardii subsp. ebusitanus. Spain. Balearic Islands, Eivissa: cala de les Torretes, 29 May 1918, Font Quer & Gros (BC 50117, lectotype) [2 specimens]; Santa Agnès, a la Cala de les Torretes, 15 June 1918, Gros (BC 50116) [1 specimen]; cala de les Torretes, 8 July 1920, Gros (BC 859210) [1 specimen]; Cala de’n Damià, 10 July 1920, Gros (BC 858975) [1 specimen]; cala de Santa Agnès, 5 m, July 1935, Gros (BC 87078, 87079) [2 specimens]; vicum Sant Mateu, cala d’Aubarca, 31SCD52, 50 m, 23 June 1979, Fernández Casas 2883 (BC 633215) [1 specimen]; Cala den Sardina, 2 June 1981, Cardona & al. (BC 644574) [1 specimen]; Cala den Sardina, 20 June 1983, L. Llorens (Herb. Univ. Illes Balears) [1 specimen]; Ses Balandres, 31SCD5523, 131 m, 3 June 2010, C. Benedí & L. Sáez (L. Sáez, herb. pers.) [5 specimens].

Thymus richardii subsp. aureopunctatus. Bosnia and Herzegovina. Konjic, Dužani, 43.509894N 18.152114E, 830 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.) [7 specimens]; Konjic, Džepi, 43.675506N 18.011992E 757 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.); [7 specimens]; Dudle, 43.540567N 18.121261E, 1034 m, 10 July 2020, F. Bogunić (SARA, ZAGR, L. Sáez herb. pers.) [7 specimens].

Thymus richardii subsp. nitidus. ITALY. Sicily, Marettimo s.d., s.r. (PAL) [3 specimens]; Isola di Marettimo, rupi di P. Anzine, 21 July 2007, Scuderi (VAL 184304) [1 specimen].