Justicia mexiae T.F. Daniel, 2019

Daniel, Thomas F., 2019, New and Reconsidered Mexican Acanthaceae XIII. Justicia, Proceedings of the California Academy of Sciences 66 (3), pp. 61-85 : 71-73

Justicia mexiae T.F. Daniel , sp. nov.

TYPE.— MEXICO. Guerrero: Distr. Aldama, Sierra Madre del Sur, N of Río Balsas, Temisco , Barranca El Salto , [ca. 18° 8′17.20′′N, 100°13′34.94′′W], 350 m, 3-XI-1937 (flr), Y. Mexia 8732 (holotype: MO!; isotypes: CAS!, F!, GH!, LL!, NY!, US!) . Figures 5-7 .

Shrubs of unknown height. Young stems 2-fariously pubescent with mostly antrorse to antrorsely appressed eglandular trichomes 0.2–0.7 mm long, trichomes mostly restricted to the 2 bands but soon becoming sparse and/or intermixed with retrorse to retrorsely appressed eglandular trichomes. Leaves petiolate, petioles 5–18 mm long, blades ovate-elliptic to elliptic, 60–121 mm long, 20–52 mm wide, (1.8–) 2.2–3.3 × longer than wide, not or only slightly reduced in size distally, acuminate at apex, (acute to) subattenuate to attenuate at base, adaxial surface sparsely pubescent with flexuose to antrorse eglandular trichomes to 1 mm long, abaxial surface sparsely pubescent along veins with similar trichomes, junctions of midvein with second-order lateral veins ± densely pubescent with a cluster of trichomes (i.e., with domatia), margin ± entire, sparsely ciliate only proximally or ± throughout. Inflorescence of axillary and terminal (i.e., in axils of distalmost pair of leaves) dense headlike dichasiate clusters (± appearing as verticels, especially at apex of shoot); clusters opposite at nodes, apparently 1 per axil, multi-flowered, sessile. Bracts dark colored (when dry), obovate to subcircular to oblate, 7–11 mm long, 3.9–9 mm wide, round- ed to acute at apex, abaxially and marginally pubescent with mostly antrorse to antrorsely appressed eglandular trichomes 0.05–0.4 mm long, distal portion of bracts erect. Bracteoles oblong to obovate to obovate-spatulate to narrowly oblanceolate, 7–10 mm long, 0.6–8 mm wide, becoming progressively narrower from primary to tertiary pairs, abaxially and marginally pubescent like bracts, distal portion of bracteoles erect. Flowers sessile. Calyx 5-lobed, 5.5–6.5 mm long, lobes homomorphic, ovate to lance-linear to linear, 4.5–5.5 mm long, 1–2 mm wide, apically attenuate to aristate (arista to 0.5 mm long), abaxially pubescent like bracts, margin distally ciliate with flexuose to crinkly eglandular trichomes to 0.4 mm long. Corolla red, 26–30 mm long, externally pubescent with erect to flexuose eglandular trichomes to 0.7 mm long, tube gradually expanded distally, 16–20 mm long, 3.8–4 mm in diameter (measured flat) at mouth, upper lip 9–13 mm long, entire at apex, lower lip 9–12 mm long, 3-lobed, lobes 0.5–3 mm long, 1–2.5 mm wide, central lobe largest. Stamens 11–15 mm long, filaments distally glabrous, proximally pubescent with eglandular trichomes, thecae of a pair subparallel to subsagittate, unequally inserted (overlapping by 1.5–1.7 mm), 1.8–2.3 mm long, subequal in length, glabrous, lacking basal appendages. Pollen 2-aperturate, apertures consisting of a narrow colpus with a prominent central os, flanked on each side by 2–3 rows of insulae (farthest rows from aperture sometimes partially or entirely consisting of peninsulae). Style 25–28 mm long, distally glabrous, proximally pubescent with eglandular trichomes; stigma asymmetrically subcapitate, 0.2 mm long. Capsule and seeds not seen.

PHENOLOGY.— Flowering: November; fruiting: unknown.

DISTRIBUTION AND HABITAT.— Mexico (north-central Guerrero; Fig. 5 ); plants were noted to be common in undergrowth on a wooded slope at an elevation of 350 m.

LOCAL NAME.— “Chilillo” ( Mexia 8732).

CONSERVATION.— This species is known only from the type collection made in 1937. Without additional information or known threats, following IUCN (2017) guidelines, it is provisionally assessed as data deficient ( DD) .

DISCUSSION.— It is not without hesitation that Justicia mexiae ( Fig. 7 ) is described as distinct from J. matudae (see above); additional collections may reveal them to be a geographic variants of a single species or entirely conspecific. However, at this time, the distinctions noted in the key below appear to warrant their recognition at specific rank. Although the pollen of both species is very similar, among grains studied to date, those of J. mexiae ( Fig. 6 ) often have fewer rows of insulae flanking the aperture than those of J. matudae . As in J. matudae it is not entirely clear whether the dense axillary clusters are expanded dichasia lacking peduncles/pedicels (therefore with only bracteoles of several orders present) or, as treated here, a reduced dichasiate spike (lacking a rachis) with bracts and bracteoles present. The bracts and bracteoles of J. mexiae are apparently tinged reddish, and are usually darker than the leaves on drying.

1a. Leaves subsessile or with petioles 2–7 mm long, blades subcordate to rounded to acute at base, abaxial surface pubescent throughout and lacking dense clusters of trichomes (domatia) at junctions of midvein and secondary lateral veins (if possibly present, then inconspicuous); bracts and bracteoles often distally recurved; calyx 6–8 mm long with lobes 2–4 mm long; style glabrous throughout; México and Michoacán ................................................................. J. matudae

1b. Leaves petiolate with petioles 5–18 mm long, blades (acute to) subattenuate to attenuate at base, abaxial surface sparsely pubescent with trichomes restricted to veins, and with dense clusters of trichomes at junctions of midvein with second-order lateral veins (domatia); bracts and bracteoles erect; calyx 5.5–6.5 mm long with lobes 4.5–5.5 mm long; style distally glabrous and proximally pubescent; Guerrero ............................................................................... J. mexiae

Figures

FIGURE 5. Map of part of southern Mexico showing distributions of Justicia amplifolia, J. matudae, J. mexiae, and J. olmeca.

FIGURE 6. Scanning electron micrographs of Justicia pollen II. A–B. Justicia totonaca (Ventura 15945). A. Apertural view. B. Interapertural view. C. Justicia mexiae, apertural view (Mexia 8732). D–F. Justicia matudae. D. Apertural view (Steinmann 4528). E. Interapertural view (Matuda et al. 31440). F. Polar view (Matuda et al. 31440). Scales = 10 µm.

FIGURE 7. Justicia mexiae (Mexia 8732). A. Habit (MO). B. Domatia on abaxial surface of leaf (US). C. Close-up of domatia in axil of midvein and secondary vein (US). D. Inflorescence (MO). E. Close-up of bracts, bracteoles, and base of flowers (CAS)