Justicia huallagensis R. Villanueva & J. R. I. Wood, 2025

Villanueva-Espinoza, Rosa, Deng, Yunfei, Scotland, Robert & Wood, John R. I., 2025, Preliminary notes on Justicia (Acanthaceae) in Peru, PhytoKeys 258, pp. 1-123 : 1-123

42. Justicia huallagensis R. Villanueva & J. R. I. Wood sp. nov.

Type.

Peru • San Martin, Prov. San Martin, 15 km E of Shapaja on road to Chazuta, Quebrada Chumia, near Mal Paso, Chumia on Río Huallaga , 6°36'S, 76°10'W, 250–300 m, 4 Aug. 1986, S. Knapp 7879 (holotype MO-3518887 , isotypes F-1992309 , US-3082657 ) .

Diagnosis.

A new species resembling Justicia malacophylla Leonard in having the inflorescence formed of long axillary and terminal spikes, mostly> 8 cm long, and in the persistent linear or lanceolate bracts, but differing in the glabrous leaves (not abaxially pubescent), longer, linear bracts 12–22 mm long with recurved tips (not 5–7 mm long, lanceolate with erect tips) and a white corolla 5–5.5 cm long (not red, 3.5–4 cm long).

Description.

Shrub to 1.5 m high; stems somewhat sulcate, glabrous. Leaves petiolate, equal or unequal in each pair, lamina 6–27 × 2.5–10 cm, broadly oblong-elliptic, apex acuminate, base attenuate, both surfaces glabrous, lateral veins 13–15 pairs, adaxially with abundant small cystoliths, abaxially paler; petioles 0.4–5 cm, glabrous. Inflorescence of terminal and axillary, spikes arising from the upper leaf axils, the terminal spikes up to 14 cm long, the axillary spikes shorter, the lowermost apparently infertile, flowers up to 15 mm apart, mostly in opposite pairs; peduncles 1.5–3.4 cm, glabrous; bracts at base of terminal inflorescence, foliose, petiolate, c. 1.5 × 0.5 cm; rachis glabrous; floral bracts linear, acute, 15–20 × 1 mm, puberulent; bracteoles similar but shorter and narrower, c. 12–14 × 0.5–1 mm; calyx 5 - lobed to near base, lobes 14–16 × 1 mm, linear, acuminate, minutely puberulent; corolla 5–5.5 cm long, white, pubescent on the exterior, 2 - lipped, tube 40 × 3 mm; upper lip c. 15 mm long, notched, lower lip slightly longer, shallowly 3 - lobed, lobes c. 1.5 mm long, the laterals ovate, the central rounded; filaments with a few scattered hairs, anthers included, thecae c. 2.5 × 0.75 mm, oblong, both with a short basal appendage, parallel, superposed, glabrous; pollen prolate, 33–35 × 23–25 μm, 2 - aperturate, colporate, 1–2 rows of indistinct insulae either side of the aperture (Fig. 52 C ); style glabrous. Capsule 17–18 × 2.5 cm, weakly clavate, puberulent, 4 - seeded; seeds rounded, c. 2.25 mm dia., rugose.

Illustration.

Fig. 42 .

Etymology.

The epithet “ huallagensis ” refers to the Río Huallaga, whose valley runs through San Martin and is the site of many endemic species, including several species of Justicia .

Phenology.

Found in flower at the beginning of August.

Habitat.

Humid lowland tropical forest along a stream, 300 m.

Distribution.

Endemic to Peru and only known from the type locality in San Martin. Fig. 68 .

Material examined.

Peru • San Martin: Type collection .

Note.

The bracts are longer than the calyx and bracteoles and often become twisted, giving the inflorescence an untidy, “ whiskery ” appearance. The white corolla is also notably long. The relationships of this species are not obvious.

Figures

Figure 42. Justicia huallagensis A habit B detail of abaxial surface of the leaf C bract D bracteole E calyx F corolla opened out to show stamens G anther H capsule, exterior (left), interior (right), J seed. Drawn from Knapp 7879 by Margaret Tebbs

Figure 52. Pollen images A Justicia bambusiformis (Dudley 10440) B J. valenzuelae (Valenzuela 8722) C J. huallagensis (Knapp 7879) D J. oxapampensis (Villanueva 963) E J. falcifolia (Ortiz 660) F J. hyalina (Scolnik 909). Scale bars: 10 μm.

Figure 68. Distribution of Justicia oxapampensis (yellow triangles), J. lactiflora (red circles) and J. huallagensis (light blue square) in Peru.