Carlowrightia yucatanensis T.F. Daniel, 2017

Daniel, Thomas F., 2017, New and Reconsidered Mexican Acanthaceae XII, Proceedings of the California Academy of Sciences 64 (7), pp. 131-154 : 131-135

Carlowrightia yucatanensis T.F. Daniel , sp. nov.

Carlowrightia yucatanensis differs from its congeners by the combination of being perennial herbs or shrubs to 1.5 m tall; having corollas entirely white, pseudopapilionaceous, and 8‒12 mm long; having capsules pubescent with eglandular trichomes only; and having seeds with the margin ± swollen and pectinate.

TYPE.— MEXICO. Yucatán: Mpio. Panabá, ca. 10 km N of Panabá toward San Felipe , 21°23.3ʹN, 088°14.9ʹW, 3 m elev., subdeciduous forest, 26-II-2003 (flr, frt), T. Daniel, G. Carnevali & J. Tapia 10320 (holotype: MEXU!; isotypes: CAS!, CICY!, COLO!, F!, K!, MICH!, MO!, NY!, RSA!, US!).

Perennial herbs or shrubs to 1.5 m tall. Young stems subterete to subquadrate, pubescent with flexuose to antrorse to retrorse eglandular trichomes to 0.8 mm long and distally sometimes with erect subglandular and/or glandular trichomes to 0.3 mm long as well, trichomes ± concentrated in 2 lines. Leaves (sometimes absent or nearly so during anthesis) petiolate, petioles to 20 mm long, blades ovate to elliptic to narrowly elliptic, (10–) 22‒69 mm long, (4.5–) 6. 5‒32 mm wide, 1.6‒4.8 times longer than wide, subacuminate to acuminate at apex, acute to rounded to subcordate at base, surfaces pubescent with mostly antrorse eglandular trichomes, margin flat, ciliate with antrorse trichomes. Inflorescence of axillary and terminal dichasiate spikes, these often branched and forming panicles of spikes, rachis evenly pubescent with erect to flexuose glandular and eglandular trichomes 0.05‒ 0.3 mm long, branches of panicles (when present) subtended by subulate to linear, sterile inflorescence bracts up to 9 mm long; dichasia (opposite, subopposite or) alternate, sessile, 1‒many-flowered. Bracts subtending dichasia opposite to subopposite, subulate to lanceolate, 1‒2 mm long, 0.4‒ 0.5 mm wide, abaxial surface pubescent like rachis. Bracteoles triangular-subulate to lance-subulate, 0.9‒ 1.5 mm long, 0.4‒ 0.6 mm wide, abaxial surface pubescent like rachis. Flowers sessile to subsessile (i.e, borne on pedicels to 0.5 mm long). Calyx 2.2‒4. 5 mm long, abaxially pubescent like rachis, lobes subulate to triangular-subulate, 1.1‒2. 9 mm long. Corolla entirely white, 8‒12 mm long, externally glabrous except lower-central lobe (and extending to tube) externally pubescent with erect to flexuose eglandular trichomes 0.2 mm long, tube 2‒ 2.8 mm long, upper lip 8‒9. 5 mm long, 1.5‒ 3 mm wide, apically 2-fid with lobes to 0.1 mm long, lower lip 6‒10 mm long, lobes 5. 3‒8 mm long, 2. 2‒4 mm wide, lower-central lobe conduplicate and partially enclosing stamens. Stamens 5.5‒8. 5 mm long, filaments glabrous, thecae 1.3‒ 1.8 mm long; pollen euprolate to perprolate, 3-colporate, 6-pseudocolpate, polar diameter 48–50 μm, equatorial diameter 24–26 μm, colpi flanked on each side by a pseudocolpus, colpi 6.7 μm wide at equator, colpal surface microechinate, intercolpal surface bireticulate. Style 8‒10 mm long, glabrous, stigma lobes 0.1– 0.15 mm long. Capsule 9. 5‒14 mm long, pubescent with erect to flexuose eglandular trichomes 0.05‒ 0.2 mm long, stipe 4‒7 mm long, head 6‒7 mm long. Seeds up to 4, 4‒ 4.1 mm long, 4‒ 4.2 mm wide, surfaces papillate, margin ± swollen and pectinate with subconic tubercles (these sometimes united with one another and appearing as an irregularly pectinate wing).

PHENOLOGY.— Flowering: February–March, July; fruiting: February–March.

DISTRIBUTION AND HABITAT.— Southern Mexico (Yucatán; Fig. 1 ); plants occur on limestone in thornscrub, tropical deciduous forest, and tropical subdeciduous forest at elevations from near sea level to 17 m. Plants were observed in forest understory, forest edges, cut-over forest, successional fields, and disturbed areas .

ILLUSTRATIONS.— Figures 2 , 3. CONSERVATION .— The species has been recorded from at least six sites in the dry, northern portion of the Yucatan Peninsula, where it has an EOO of 1904 km 2. At two sites plants were observed to be locally frequent to common (e.g., ca. 50 individuals within 50 m 2). Like many of its congeners, C. yucatanensis often occurs in disturbed habitats (e.g., along roadsides). There appears to be considerable habitat for this species in this portion of the peninsula, and it occurs in at least one protected landscape (Reserva Río Lagartos). Although human population pressures and climatic changes will impact (either negatively or positively?) the distribution and numbers of individuals of this species, there are currently no immediate threats that have been identified. Thus, given its apparently restricted distribution, a preliminary assessment of Near Threatened (NT) is proposed for this species using IUCN criteria ( IUCN 2017).

PARATYPES.— MEXICO. Yucatán: alrededores de la zona arqueológica de Mayapan, 1 km S de Telchaquillo , carr. Tecoh – Oxkutzcab, [ca. 20.628200, -89.460844] E . Cabrera & H . de Cabrera 9120 ( MO); 4–6 km W de Las Coloradas, camino al crucero San Felipe–Río Lagartos , [ca. 21.609482, -88.048721], E . Cabrera & H . de Cabrera 15739 ( CICY, CIQR, MEXU, MO); Mpio. Izamal, 10–12 km W Tunkas de Izamal, carr. a Tunkas , ca. 20°54ʹN, 88°50.5ʹW, G . Carnevali et al. 4381 ( CICY); Mpio. Río Lagartos, entre el camino Río Lagartos rumbo a Las Coloradas , 21°34ʹN, 88°10ʹW, C . Chan 4796 ( CICY); Mpio. Río Lagartos, camino de Río Lagartos rumbo a Las Coloradas , 21°36.5ʹN, 88°03ʹW, C . Chan 4809 ( CICY); Mpio. Sucila, along hwy. 176 between Buctzotz and Sucila (27 km W of Sucila), 21°10.5ʹN, 088°28.8ʹW, T . Daniel, G . Carnevali, & J . Tapia 10312 ( CAS, BR, CICY, DUKE, F, K, MEXU, MO, NY, US).

DISCUSSION.— Based on several morphological similarities (e.g., pubescent capsules, swollen and irregularly pectinate margin of the seed), Carnevali et al. (2005) treated plants of Carlowrightia yucatanensis from the Yucatán Peninsula as a third distinctive population of C. hintonii T.F. Daniel. Since then, reexamination of materials from these populations reveals that the morphological distinctions of plants from the Yucatán Peninsula are more reflective of a distinct species than a variant of C. hintonii . The following key summarizes distinctions between them.

1a. Corollas white with a papillate (yellow?) eye on upper lip, 15–18. 5 mm long, tube 7–8. 5 mm long, lobes of lower lip widely spreading (i.e., at angles ≥ 45°) from lower-central lobe; bracteoles (at fertile nodes of inflorescences) 1.5– 2.5 mm long; filaments pubescent with trichomes to 0.1 mm long; pubescence of capsule all or chiefly glandular (in some plants from El Salvador, capsules all or chiefly eglandular); Pacific versant with plants occurring at elevations at or above 380 m. .................................................... C. hintonii

1b. Corollas entirely white (lacking a papillate eye of any color on upper lip), 8–12 mm long, tube 2– 2.8 mm long, lobes of lower lip spreading from lower-central lobe at angles ˂ 45°; bracteoles (at fertile nodes of inflorescences) 0.9– 1.5 mm long; filaments glabrous; pubescence of capsule entirely eglandular; Caribbean versant with plants occurring at elevations from sea level to 20 m. .................................................. C. yucatanensis

Plants observed in late February (Daniel et al. 10312, 10320) showed massive flowering over several days with plants covered in flowers. These were visited by two kinds of small to mediumsized butterflies, honey bees, and smaller bees or flies. Corollas began dehiscing and falling in light winds at 13:45, which conforms to observations made on other species of the genus elsewhere in the United States and Mexico ( Daniel 1983).

Based on morphological characters, Carlowrightia yucatanensis would pertain to section Papilionaceae of Daniel (1983). However, molecular phylogenetic data ( Daniel et al. 2008; McDade et al. in press) reveal that neither the genus nor this section is monophyletic. Indeed, the results of McDade et al. (in press; as C. hintonii ) reveal that the placement of C. yucatanensis relative to its congeners is ambiguous, depending on analytical method. Pollen of C. yucatanensis ( Fig. 4A, B ) conforms to that otherwise known for the genus ( Daniel 1983, 1998). Macromorphological differences between C. yucatanensis and C. myriantha (Standl.) Standl. , the only other species of the genus to occur in the Yucatán Peninsula, were summarized by Daniel (1993) and Carnevali F. et al. (2005).

Figures

FIGURE 1. Map of southern Mexico (and northern Central America, shaded) with distributions of Carlowrightia yucatanensis (Yucatán), Justicia zapoteca (Oaxaca), Poikilacanthus foliosepalus (Oaxaca), and P. pochutlensis (Oaxaca).

FIGURE 2. Carlowrightia yucatanensis. A. Shoot with inflorescence. B. Leaf. C. Inflorescence nodes with corolla dehisced (bottom) and corolla present (top) in side-view. D. Magnification of inflorescence rachis. E. Corolla in front-view. F. Distal portion of stamen with bithecous anther, side-view (left) and front-view (right). G. Distal portion of style and stigma. H. Capsule with one seed. I. Magnification showing pubescence on surface of capsule. J. Seed. K. Magnification of seed margin. (A, B from Daniel et al. 10312; C–K from Daniel et al. 10320). Drawn by Amy Whitesides

FIGURE 3. Photographs of Acanthaceae. Carlowrightia yucatanensis (Carnevali et al. 4381), habit (top left) and flower (top middle); Poikilacanthus pochutlensis (Daniel & de Avila 12204), apex of shoot with mature flower bud (top right) and Cerro Espino, locale of only known collections (middle right); Justicia zapoteca (Daniel et al. 11898cv), apex of shoot with inflorescence and flowers (bottom left), seed (middle center), and flower (bottom right). Photos by the author, except C. yucatanensis photos by G. Carnevali F. (used with permission).

FIGURE 4. Pollen of Acanthaceae. A, B. Carlowrightia yucatanensis (Daniel et al. 10320), apertural view (A) and interapertural view (B). C. Justicia zapoteca (Saynes V. & Elorsa 2741), apertural view. D, E. Poikilacanthus foliosepalus (Hernández O. 326), apertural view (D) and interapertural view (E). F. Louteridium dendropilosum (Fernández N. 4189). G, H. Poikilacanthus pochutlensis (Torres & Martínez 4907), subpolar view (G) and polar view (H). I. Louteridium dendropilosum (Daniel et al. 11784), with internal contents extruding via pores.