Clinopodium eplingianum J.G.González, Martorell & D.García, 2024

González-Gallegos, Jesús Guadalupe, Martorell, Carlos & García-Meza, Diego, 2024, Clinopodium eplingianum (Lamiaceae), a new species from Oaxaca, Mexico, Phytotaxa 653 (3), pp. 197-207 : 200-204

Clinopodium eplingianum J.G.González, Martorell & D.García , sp. nov. ( Figure 1 & 2 ).

Type:— MEXICO. Oaxaca, Mpio. San Francisco Teopan: paraje Hoya del Malacate , 17º51’7” N, 97º30’44” W, 2640 m, 2 October 2023, D. García-Meza X1131 (holotype CIIDIR, isotypes FCME, HUAP, IBUG, IEB, MEXU, OAX).

Diagnosis:— Clinopodio hintoniorum maxime similis, praecipue in habitu et ramificatione, sed laminae basi rotundata (vs. in petiolum abrupte decrescens), margine minute sparsimque serratis (vs. integris), foliorum lamina comparate latiore (6–17 vs. 6–8 mm), calyce dentibus subulatis et nudis inter se (vs. triangularis et pubescentibus inter se) et dentibus superis longioribus (3–3.8 vs. 1–1.6 mm longis), et corollae tubo calycem aequantes (vs. plus quam duplo longiore) differt.

Shrub, erect, up to 1 m tall; profusely branching, stems of the branchlets hispidulous with the hairs slightly retrorse, older branches glabrescent to glabrous. Leaves with a strong minty scent; petioles 2–4.2 mm long, articulated into a thicker and more lignified base (especially those from older branches), hispidulous with slightly retrorse hairs, and with translucent golden glandular dots; blade elliptic, ovate to ovate-deltoid, 1.2–2.6 × 0.6–1.7 cm, apex acute, base rounded, margin minutely and sparsely serrulate, both surfaces with hispidulous hairs along the veins and puberulent, beneath with profuse translucent golden glandular dots. Inflorescences in cymes in the axils of progressively reduced leaves to the terminal portion of the branches, regularly 2–8 floral nodes, compact or with internodes up to 4 cm long, cymes with peduncles 1.9–3.5 mm long, 3–5 flowered; floral bracts linear, 1.6–2.1 mm long, bracteoles linear, 1–1.4 mm long; floral axes, bracts and bracteoles pubescent as the stems and with some translucent golden glandular dots. Flowers with pedicels 0.7–1.9 mm long, puberulent, hispidulous and with translucent glandular hairs. Calyx tubular and slightly arcuate upwards, tube 4.9–6.2 × 1.3–1.8 mm, plicate by the elevated veins, hispidulous, puberulent and covered with translucent golden glandular dots, internally glabrous to sparsely puberulent, no inner tube hairs projected between the calyx teeth; lips scarcely differentiated, lobes linear, similar in shape and partially in size, ciliated along the margin; three upper lobes basally fused by 0.5–0.8 mm, 3–3.8 mm long, two lower ones free and 2–2.9 mm long. Corolla violet to light purple, with irregular white marks on the lower lip an close to the throat, tubular, gradually ampliated from the middle to the throat, slightly arcuate upwards as the calyx, externally short pilose with the hairs concentrated to the lips, glabrous inside except by the bifurcation line between the throat and the lower lip and the attachment line of the lower filaments, being short pilose, tube 8.6–13.5 × 1.9–3.8 mm; upper lip emarginate, slightly galeate, (1.4–) 2.8–4.1 mm long; lower lip trilobate, patent to deflexed, 3.9–5 × (4.4–) 6–7.8 mm, extended. Stamens 4, included below upper corolla lip, didynamous, the lower (anterior) pair with filaments 3.3–5.6 mm long and thecae 0.4–0.8 mm long, the upper (posterior) pair with filaments 1.9–2.9 mm long and thecae 0.4–0.6 mm long, filaments glabrous except by the base of the lower ones, being hispidulous, thecae sparsely hispidulous, basally divergent by a gap due to the thickened connective, this 0.3–0.4 × 0.2–0.3 mm. Gynobase 1–1.3 mm long; style 12.3–15.3 mm long, glabrous, stigmatic branches minute and usually appressed, the upper 0.1–0.5 mm long, the lower 0.8–1 mm long. Mature mericarps not seen, the immature ovoid, glabrous and concolorous.

Distribution, habitat and ecology:— Clinopodium eplingianum is currently considered endemic to northwestern Oaxaca, in the Mixteca region and Coixtlahuaca district, nestled in Sierra Madre del Sur biogeographic province; since it has been recorded just at about 12 km (air distance) to the border with Puebla state, it is also probable that it would eventually be found there ( Figure 3 ). It grows in semiarid oak-savanna vegetation at an elevation between 2600–2700 m. The highly diverse continuous herbaceous layer is dominated by Bouteloua chondrosioides (Kunth 1816: 173) Benth. ex Watson (1883: 179) , Microchloa kunthii Desvaux (1831: 179) , Cyperus seslerioides Kunth (1815: 209) , Thymophylla aurantiaca ( Brandegee 1908: 258) Rydberg (1915: 175) , and Tridax coronopifolia ( Kunth 1820: 200) Hemsley (1881: 207) , with scattered Quercus deserticola Trelease (1924: 79) trees. Even though these areas are not flooded, large sections are covered by Isoëtes mexicana Underwood (1888: 93) . Clinopodium eplingianum shares its habitat with several threatened or rare species, such as Echeveria longissima Walther (1938: 147) , Calochortus nigrescens Ownbey (1940: 530) , Lobelia oaxacana Rzedowski (2016: 14) and Salvia tetramerioides Martínez-Gordillo et al. (2016: 217) . The latter is also probably microendemic to these savannas.

Phenology:— It probably flowers from late autumn through the winter, fruiting at the end of winter and through the spring, deduced from the type specimens collected with flowers and immature fruits at the beginning of October. The specimens collected in March had few flowers and reduced leaves, hence most likely being late flowering individuals.

Etymology:— This new Clinopodium is named in honor to Carl Epling (1894–1968), a very prolific researcher who is still the main reference for the understanding of the New World labiates. He produced more than 100 publications from 1925–1968, the largest portion dealing with taxonomic revisions of Lamiaceae genera and contributions by treatments of this family to floras at country or regional scale ( Mathias 1970). Seven species have already been dedicated on his name ( Tropicos 2024).

Conservation status:— Clinopodium eplingianum is currently known from two very close localities, with a straight distance no more than 1.4 km. There are not specific threats identified for the species. Therefore, applying criterion B of IUCN (2024), the new species is not threatened. However, it is desirable to increase botanical exploration in the region to better document its distribution and conservation status. It would be also possible that the species could be found within the polygon of the Tehuacán-Cuicatlán Biosphere Reserve, being that it is located at about 15.5 km from the closest boundary of the reserve. Therefore, we previously assess C. eplingianum as Data Deficient ( IUCN 2024).

Uses:— This species is locally known as chipito morado, “purple chipito”, and used as an infusion for treating intestinal disorders. “Chipito” is an ethnotaxon that comprises a few aromatic Lamiaceae with medicinal uses, such as Salvia regla Cavanilles (1799: 33) . Despite the apparent geographic rarity of C. eplingianum , the plant is locally abundant in one of its known sites and it is likely to occur in small patches in the vicinity of the collection sites where it can be easily accessible to the many pastoralists that constantly comb these oak savannas. The exhaustive checklist of medicinal flora of Oaxaca ( Cruz-Pérez et al. 2021) mentions three other useful Clinopodium species ( C. brownei , C. macrostemum , and C. mexicanum ), none of which can be mistaken for this new species. It thus seems unlikely that it has been previously reported under any other name.

Additional specimen examined:— MEXICO. Oaxaca, Mpio. San Pedro Teopan: Cuseya, 17º51’39” N, 97º30’22” W, 2600 m, 14 March 2022, C. Martorell & D. García-Meza X852 (CIIDIR).

Notes:— Following the recently published identification key to Mexican Clinopodium species ( González-Gallegos et al. 2023), Clinopodium eplingianum is most similar to a set of three shrubby species from northern Mexico. Two of the species come from the California Floristic Province, C. chandleri and C. ganderi , and the other from Nuevo León, C. hintoniorum ( Turner 1993: 411) Govaerts (1999: 17) . These species are similar to C. eplingianum , additionally to the shrubby habit, in having petioles longer than 1 mm, leaves wider than 5 mm, cymes up to 6-flowered, included stamens, and bluish to pale violet or purple corollas. There is no clear morphological close affinity to either of them, since some characters are akin to the Californian species and others to C. hintoniorum , though it resembles the latter species the most in general habit and architecture. The new species can be distinguished from C. hintoniorum by the rounded leaf blades at the base (vs. abruptly tapering upon the petiole), minutely and sparsely serrate margins (vs. entire), relatively wider leaves (6–17 vs. 6–8 mm), subulate calyx teeth without protruded hairs between them (vs. triangular with hair tufts between them), the upper teeth also longer (3–3.8 vs. 1–1.6 mm long), and the corolla tube as long as the calyx with only the lips surpassing the calyx teeth (vs. corolla tube more than twice the total length of the calyx, then with a large portion of the tube surpassing calyx teeth). Clinopodium chandleri differs in the obtuse apex of the leaves (vs. acute), truncate and abruptly cuneate bases (vs. rounded), relatively longer petioles (4.4–6.6 vs. 2–4.2 mm), the absence of a thicker basal articulation in the petiole, wider calyx tube (2–3.4 vs. 1.3–1.8 mm), shorter upper calyx lip (1–2.4 vs. 3–3.8 mm), triangular calyx lobes (vs. long subulate) and reflexed in fruit resembling a star in frontal view (vs. straight), presence of protruding hairs between calyx lobes, and corolla color (cream white vs. violet to light purple). Clinopodium ganderi sets apart also by different shape in the apex and base of the leaves (apex obtuse, base rounded and then attenuate or subcuneate vs. acute and rounded, respectively), usually longer petioles (3–10 vs. 2–4.2 mm) and often shorter leaf blades (6.5–13.5 vs. 12–26 mm), wider calyx tube (2–3 vs. 1.3–1.8 mm), and shorter upper calyx lip (2–2.5 vs. 3–3.8 mm) and different in shape (triangular vs. long subulate), and in corolla color variation (lavender, lavender pink, light violet or white vs. violet to light purple; according to specimens’ labels, corolla color varies markedly depending on the degree of corolla maturation in C. ganderi ).

Clinopodium eplingianum also differs in biogeography an ecological affinity, being a plant restricted to the biogeographic province of Sierra Madre del Sur, according to the delimitation of Morrone et al. (2017), inhabiting semiarid oak-savanna. In contrast, both Californian species grow in the California province mainly in coastal sage scrub, and in chaparral under a Mediterranean climatic regime ( Wiggins 1980, Rebman & Roberts 2012). Clinopodium hintoniorum is also the most similar in habitat to the new species, it also grows mainly in semiarid vegetation with scattered low oaks and ample areas with grasses (oak chaparral); however, it is nested into the northern portion of Sierra Madre Oriental Province with an air-line distance of about 720 km.

Figures

FIGURE 1. Clinopodium eplingianum A. Portion of a plant with flowering branches, B. Flower, C. Lateral view of the corolla, D. Upper and lower stamens, E. Apical portion of the style showing the stigmatic branches, F. Gynobase and carpels (Drawn from the type specimens by J.G. González-Gallegos).

FIGURE 2. Holotype specimen of Clinopodium eplingianum.

FIGURE 3. Distribution map of Clinopodium eplingianum. Color shades representing the biogeographic provinces according to Morrone et al. (2017): Balsas Basin (white), Chiapas Highlands (violet), Pacific Lowlands (yellow), Sierra Madre del Sur (green emerald), TransMexican Volcanic Belt (brown), and Veracruzan (yellow-green). Tehuacán-Cuicatlán Biosphere Reserve boundaries with red dashed line as reference.