Dicliptera mercedesiae R.Villanueva, Wassh. & Rob.Fern., 2021

Villanueva-Espinoza, Rosa, Wasshausen, Dieter & Fernandez-Hilario, Robin, 2021, Dicliptera mercedesiae, a new species of the genus Dicliptera (Acanthaceae) from Peru, Phytotaxa 518 (1), pp. 36-44 : 37-42

Dicliptera mercedesiae R.Villanueva, Wassh. & Rob.Fern. , sp. nov. ( Figs.1–3 ).

Diagnosis: — Dicliptera mercedesiae is related to D. purpurascens with regard to the number of verticillate cymes at each axil, unequal purple cymules bracts and a long corolla, but Dicliptera mercedesiae differs from this species in its subsessile flowers (not longpedicellate), elliptic cymules bracts 10–13 × 1–2 mm (not lanceolate 17–25 × 1.6–5 mm) and corolla without resupination (not resupinate).

Type: — PERU. Junín, Prov. Chanchamayo, Dist. San Ramón, Fundo Génova , 1152 m, 11°05’47.81, 75°21’39”W, 29 May 2018 (fl.), R . Villanueva & G . Bravo 72 (holotype: MOL!; isotypes: HOXA!, US!, USM!) .

Herb to 1 m tall, erect or decumbent, much-branched, cystoliths abundant. Stems hexangular, striated, swollen nodes, these with a conspicuous interpetiolar line, covered with some purplish pubescence, simple trichomes. Leaves opposite, isophyllous; petiole 0.7–3 cm long, glabrescent, green; leaf blades membranaceous, 6–18.2 × 1.3–6.2 cm, lanceolate to elliptic, apex attenuate, base attenuate, margins crenulate to entire, slightly discolorous, covered by linear white cystoliths, venation eucamptodromous, lateral veins 6–8 pairs, veins impressed and reticulation barely visible on the adaxial surface, veins prominent and reticulation plane strongly distinct on the abaxial surface, adaxial surface flat, glabrous, abaxial surface with main and lateral veins puberulent, adaxial and abaxial surfaces green with main and lateral veins orange in dried specimens. Inflorescence axillar, consisting of 3 cymes, uppermost fascicules of cymes forming a terminal spike, subtending by leaf like-bracts; cymes 3–5-flowered, 2.5–4.5 cm long (including corolla), erect; peduncle 1.8–5 mm long, terete, thin, purplish pubescence, green; main axis bracts 10–15 × 1–2 mm, equal, narrowly elliptic, apex attenuate, margin entire, submembranaceous, glandular-pilose, green to purple, venation brochidodromous, abaxial surface with midvein prominent; cymules bracts 10–13 mm long, 1–2 mm wide, unequal, elliptic, membranaceous, similar to main axis bracts but smaller; bracteoles in two pairs, unequal, elliptic to ovate, apex attenuate, margin entire, membranaceous, glandular-pilose on abaxial surface, glabrous on adaxial surface, green to purple, outer pair 7.5–9.5 × 1.0– 1.5 mm, inner pair 6–7 × 0.5–1 mm. Flowers zygomorphic, subsessile to pedicellate (up to 1 mm long), pedicel terete, thin, densely pubescent, green. Calyx 5-lobed, triangular lobes joined basally, 3–4 × 0.5–1 mm, equal, apex acute, margin ciliate, membranaceous, glandular, green to purple. Corolla bilabiate, 19–34 cm long, erect, not-resupinate, pubescent with sparse glandular trichomes on external surface, striated, nerved, orange to crimson; tube erect, 4–6.5 mm long, 1–1.5 mm diam, shorter than lips, bulbous yellowish with a white base; throat 10–19.5 mm long, erect to curved; upper lip 5–8 × 3–5 mm, elliptic, concave, antrorse at apex, internally with a stylar furrow, slightly bilobed, lobes ca. 0.4–0.5 mm long, rounded, equal; lower lip 5–8 × 3–5 mm, elliptic, concave, 3- lobed, lobes 0.5–1 mm long, rounded, equal. Stamens 2, 2.8–3.2 cm long, unequal, slightly exserted; filaments erect, light yellow, pubescent, attached to corolla throat; anther 1–1.5 mm long, bithecous, thecae superposed, muticous, glabrous, purple. Ovary 2–3 mm long, pyriform, glabrous, nectary flower disc at base; style 2–3 cm long, filiform, strigose, scattered trichomes toward the base, white; stigma 0.3–0.5 mm long, 2-lobed, glabrous, white. Capsule 5–6 × 4 mm long, orbicular, densely pubescent, retinacula present. Seeds 2, 2–2.5 × 2 mm, orbicular, compressed, yellowishbrown, papillose.

Additional specimens examined (Paratypes): — PERU. Pasco: Prov.Oxapampa, Dist.Villa Rica, Cerro Ascensor , Bosque de Protección San Matías San Carlos , 1355 m, 10°45’28”S, 74°55’92”W, 6 Jul 2003 (sterile), J . Perea & C . Mateo 198 ( HOXA!) . Junín: Prov. Chanchamayo, Dist. San Ramón, Centro Poblado de Nueva Italia , siguiendo la carretera aproximadamente 30 min, caminando rumbo hacia San Ramón , 1200 m, 11°00’44.16”S, 75°24’49.07”W, 15 Jun 2019 (fl.), R . Fernandez-Hilario 1946 ( HOXA!, MOL!, UPCB!) .

Distribution and habitat: — Dicliptera mercedesiae is known only from Central Peruvian region of Pasco and Junín ( Fig. 3 ). It grows in primary and disturbed forests, frequently along streams at elevation of 950–1350 m. In Génova Farm (Junín) (R. Villanueva & G. Bravo 72), this new species is found at undergrowth in association with Ruellia tarapotana Lindau (1904: 318) , Urera caracasana ( Jacquin 1798: 71) Gaudichaud ex Grisebach (1864: 154) , Oxalis ortgiesii Regel (1875: 1) , Thunbergia alata Bojer ex Sims (1825 : t. 2591) and Coffea arabica Linnaeus (1753: 172) .

Phenology: —This new species was observed in flowering from May to August, and fruiting in December.

Etymology: —The specific epithet refers to Mercedes Flores for cheering the first author up to research on Acanthaceae Family and also, for her total support on the undergraduate thesis elaboration process. Furthermore, for her contribution to the knowledge of Fabaceae species in Peru.

Conservation status: — Dicliptera mercedesiae is known from only three localities in the premontane forest of Central Peruvian region of Pasco and Junín. It is noteworthy that the three localities of collection for this plant are currently being seriously affected by road construction and anthropogenic transformation. Therefore, under the guidelines of IUCN (2012, 2019) and based on an estimated extent of occurrence of 330 km 2, we assign this species to the category Endangered [EN (B1a+bii)].

Discussion: — Dicliptera and Justicia Linnaeus (1753: 15) species could be confused by its bilabiate flowers, however, Dicliptera species has a typical fruit which consist of a capsule with a placenta that rises elastically at dehiscence. This distinctive fruit along with the presence of flowers subtended by paired bracts and bracteoles, allows us to determine that this new species, Dicliptera mercedesiae , belongs to the genus Dicliptera ( Balkwill et al. 1996) .

Three conditions of floral orientation are found in Dicliptera species : corolla resupinate 360°, 180° or without twisting ( Daniel 2009). Species without a tube torsion are characterized by having large, brightly colored and red, orange-yellow or purple corollas that appear to be adapted for bird pollination. Additionally, the absence of a twisted corolla is correlated to the presence of rugula ( Kiel et al. 2017). By having not-resupinate and large orange corolla and, a rugula in the upper lip of corolla, D. mercedesiae could be included in the latter group.

Dicliptera mercedesiae is superficially similar to other Neotropical species of the genus such as D. lugoi Wasshausen (2013: 85) , D. palmariensis Wasshausen & Wood (2004b: 23) , D. purpurascens , D. squarrosa and D. scandens Leonard (1958: 364–366) . All species in this group share a tubular corolla and the identical orientation of the corolla lips. However, D. mercedesiae can be distinguished from these five species by having a short-pedicellate cymules, elliptic cymules bracts with an apex attenuate, and corolla lips less than one third as long as the throat and tube. Detailed information about distinguished characters among these species are explained in Table 1.

Within Peruvian species, D. mercedesiae is morphologically related to D. squarrosa and D. purpurascens . Although, D. squarrosa presents sessile cymules, D. mercedesiae differs by its apically attenuate cymule bracts (not acute with a recurved tip) and large corolla 19–34 cm (not 18–25 cm). Regarding the second species, D. mercedesiae and D. purpurascens both share the presence of 3 verticillate cymes at each axil, unequal purple cymules bracts and a long corolla. However, D. mercedesiae has flowers sessile (not long-pedicellate), elliptic cymules bracts 10–13 × 1–2 mm (not lanceolate with a long acumen) and a corolla tube without a torsion (not resupinate).

Figures

FIGURE 1. Dicliptera mercedesiae. A. Terminal spike conforming by uppermost verticillate cymes. B. Detail of the unequal stamens and anthers, frontal view. C. Fascicules of three cymes at leaf axil. D. Detail of the orbicular capsule. E. Detail of the two seeds. From R. Fernandez-Hilario et al. 1835 (A); R. Villanueva & G. Bravo 72 (B-E). Photos by Robin Fernandez-Hilario (A); Rosa Villanueva (B–E).

FIGURE 2. Dicliptera mercedesiae. A. Terminal fertile branch with axillary inflorescences. B. Corolla bilabiate. C. Calyx 5-lobed with pistil. D. Cymule bracts (2) enclosing two pairs of bracteoles.E. Cyme 5-flowered.F. From left to right: main axis bracts, cymule bract and bracteole. G. Detail of dehiscent capsule with placenta attached to the wall capsule. From R. Villanueva & G. Bravo 72 (MOL). Drawing by Mily Valle.

FIGURE 3. Distribution map of D. mercedesiae in Peru.