Stachytarpheta minasensis (S.Atkins) P.H.Cardoso, 2022

Cardoso, Pedro Henrique, Neto, Luiz Menini, Somavilla, Nádia Silvia & Trovó, Marcelo, 2022, A morphometric approach and recircumscription of the Stachytarpheta longispicata complex (Verbenaceae), European Journal of Taxonomy 833, pp. 12-45 : 36-38

Stachytarpheta minasensis (S.Atkins) P.H.Cardoso comb. and stat. nov.

Figs 6J–L , 7G–H , 8G–H , 12

Stachytarpheta longispicata subsp. minasensis S.Atkins, Kew Bulletin 60: 231 ( Atkins 2005), basionym.

Material examined

Type BRAZIL – Minas Gerais • Serra do Cabral, Joaquim Felício ; 15 Apr. 1996; G. Hatschbach et al. 64789; lectotype: MBM [ MBM409619 ] web!, designated here; isolectotypes: CTES[ CTES0013844 ] web!, K[ K000065239 ] web!, K[ K000065396 ] web!, MBM [ MBM193011 ] web !.

Representative specimens

BRAZIL – Minas Gerais • “ Joaquim Felício, Parque Estadual da Serra do Cabral ”; 14 Sep. 2019; F.R.G. Salimena & P.H. Nobre 4051; CESJ • “ Serra do Cabral , 85 km N de Corinto ”; 13 May 1977; P.E. Gibbs et al. 5059; MBM, UEC • “ Serra do Cabral, Joaquim Felício ”; 15 May 2001; G. Hatschbach et al. 72033; MBM, RB .

Description

Shrubs 0.35–1 m tall, erect, much-branched, stems cylindrical when young, lanate, puberulent when old, xylopodium present. Leaves opposite, patent, flat, sometimes with smaller leaves on the axils, deciduous in maturity, petiolate; petiole 1.93‒4.79 mm long, lanate; blade 8.19–15.88 × 6.32–14.35 cm, ovate or fan-shaped, thickly-chartaceous, slightly discolorous, base attenuate, apex obtuse or rounded, margin entire near the base, serrate towards the apex, revolute, abaxially not foveolate, lanate, veins prominent, adaxially sericeous. Inflorescences 27.04–237(–354.53) × 18.39–23.5 mm, pendulous or not at the apex, rachis visible, lanate; bracts 3.23–6.97 × 0.83–1.59 mm, light green, triangular, apex acuminate or caudate, abaxially sparsely lanate. Flowers pedicellate, pedicel 1.15–2.39 mm long, lanate; calyx tube widened at the apex, 8.21‒14.55 × 3.2–5.29 mm, light green, lanate at base and along nerves, becoming strigose at apex, briefly 5-toothed; corolla salmon, tube 13.36‒16.35 mm long, externally with pedicellate glandular trichomes. Fruits 3.8‒5 mm long, castaneous, external surface reticulate, with thin and flat commissure, apex rounded with short stylopodium, prominent attachment scar, separating into two cluses, covered by the persistent calyx.

Distribution, habitat and phenology

Stachytarpheta minasensis is endemic to the Cerrado domain in the Serra do Cabral region, state of Minas Gerais ( Fig. 5 ). It forms large-sized but restricted populations in campos rupestres. Found fertile in April, May and September.

Proposed conservation status

Stachytarpheta minasensis is known from only two localities in Serra do Cabral, in the municipality of Joaquim Felício, with an AOO smaller than 10 km 2. Despite being found inside a protected area (Parque Estadual da Serra do Cabral), it is threatened by the continuous decline in habitat quality, especially due to livestock stomping and illegal fires, which prevail due to lack of inspection, warning and clarification (IEF 2013). Therefore, S. minasensis should be considered “Critically Endangered” (CR), based on the B2ab(i,ii,iii) criteria of IUCN (2022) due to its restricted AOO, fragmented distributions, number of known populations, and continuous decline in habitat quality.

Notes

Atkins (2005) indicated that the holotype of Stachytarpheta longispicata subsp. minasensis (Hatschbach et al. 64789) was housed at MBM. However, there are two different specimens of Hatschbach et al. 64789 at MBM; in this framework it is not possible to ascertain which one is explicitly the holotype referred to by Atkins (2005) since she did not provide a clear indication of it. Therefore, we designate as the lectotype the specimen in which the inflorescences are complete and still present corollas.

Atkins (2005) characterised Stachytarpheta longispicata subsp. minasensis as a shrub 35 cm tall, with a xylopodium, branched, spathulate or ovate leaves, blades 5–20 × 3–10 mm, inflorescences 40–70 mm long, linear bracts up to 4 mm long, and calyx up to 10 mm long with uniseriate mostly patent hairs. According to Atkins (2005), this taxon has a micro-endemic distribution, being recognised by its very small leaves. When comparing the circumscription proposed by Atkins (2005), it is possible to observe differences regarding plant stature, size of the leaf-blades, and the length of the inflorescences, bracts, calyx and corolla. Regarding the size of the leaves, Atkins (2005) provides greater measurement ranges for length. However, these measurements are most likely associated with the smaller leaves on the axil of larger leaves (for which we only recorded their presence or absence), as well as the combined values for petiole and leaf-blade length (instead of being presented separately). Atkins (2005) described the leaves as spathulate to ovate. Nonetheless, the author sometimes applied the term spathulate to describe leaves that are considered fan-shaped (P.H. Cardoso pers. obs.).

Based on our morphometric analysis, as well as qualitative characters and geographic distribution, Stachytarpheta longispicata subsp. minasensis is elevated to the species rank. Therefore, S. minasensis differs from the remaining species of Stachytarpheta with pedicellate flowers due to its diminutive leaves (8.19–15.88 × 6.32–14.35 cm), ovate or fan-shaped, with attenuate base and conspicuously serrate margin.

Figures

Fig. 6. Comparison between the main characteristics of the species used in the identification key (photos taken under the stereo microscope). A, D, G, J, M. Adaxial indumentum of the leaf-blade. B, E, J, K, N. Abaxial indumentum of the leaf-blade. C, F, I, L, O. Indumentum of the rachis, bracts, pedicel, and calyx. A–C. Stachytarpheta brevibracteata (Moldenke) P.H.Cardoso (P.H. Cardoso & W.P. Leite 66). D–F. S. longipedicellata (Moldenke) P.H.Cardoso (P.H. Cardoso et al. 59); G–I. S. longispicata (Pohl) S.Atkins (P.H. Cardoso et al. 48). J–L. S. minasensis (S.Atkins) P.H.Cardoso (F.R.G. Salimena & P.H. Nobre 459). M–O. S. ratteri (S.Atkins) P.H.Cardoso (P.H. Cardoso et al. 51).

Fig. 7. Comparison between the pubescence of the leaves of the species (photos taken under electron microscope). A, C, G, E, I. Adaxial surface. B, D, F, H, J. Abaxial surface. A–B. Stachytarpheta brevibracteata (Moldenke) P.H.Cardoso (P.H. Cardoso & W.P. Leite 66). C–D. S. longipedicellata (Moldenke) P.H.Cardoso (P.H. Cardoso et al. 59). E–F. S. longispicata (Pohl) S.Atkins (P.H. Cardoso et al. 48). G–H. S. minasensis (S.Atkins) P.H.Cardoso (F.R.G. Salimena & P.H. Nobre 459). I–J. S. ratteri (S.Atkins) P.H.Cardoso (P.H. Cardoso et al. 51).

Fig. 8. Comparison between the pubescence of the calyx of the species (photos taken under electron microscope). A, C, G, E, I. The most basal part. B, D, F, H, J. The most apical part. A–B. Stachytarpheta brevibracteata (Moldenke) P.H.Cardoso (P.H. Cardoso & W.P. Leite 66). C–D. S. longipedicellata (Moldenke) P.H.Cardoso (P.H. Cardoso et al. 59). E–F. S. longispicata (Pohl) S.Atkins (P.H. Cardoso et al. 48). G–H. S. minasensis (S.Atkins) P.H.Cardoso (F.R.G. Salimena & P.H. Nobre 459). I–J. S. ratteri (S.Atkins) P.H.Cardoso (P.H. Cardoso et al. 51).

Fig. 12. Stachytarpheta minasensis (S.Atkins) P.H.Cardoso comb. and stat. nov. A. Habitat. B. Habit. C–D. Individuals showing details of the leaves and inflorescences, highlighting the short pedicels, bracts, calyxes, and corollas. Photos by Pedro Henrique Nobre.

Fig. 5. Distribution map of the five species recognised in the Stachytarpheta longispicata complex in the present study. The triangles represent localities sampled during fieldwork for the morphometric analysis.