Louteridium rzedowskianum T.F. Daniel, Proc. Calif. Acad. Sci.

Daniel, Thomas F. & Tripp, Erin A., 2018, Louteridium (Acanthaceae: Acanthoideae: Ruellieae: Trichantherinae): Taxonomy, Phylogeny, Reproductive Biology, and Conservation, Proceedings of the California Academy of Sciences 65 (2), pp. 41-106 : 98-99

10. Louteridium rzedowskianum T.F. Daniel, Proc. Calif. Acad. Sci. 64:144. 2017 . Louteridium brevicalyx Rzed., Ciencia (México) 28:53. 1973, nom. inval., non Louteridium brevicalyx A. Richardson (1972) . Louteridium rzedowskii T.F. Daniel, Madroño 31:91. 1984, nom. inval. TYPE.— MEXICO. Guerrero: Mpio. Chilpancingo, Rincón de la Vía, cerca de Agua de Obispo

[ ca. 17°17’45.05”N, 099°28’17.54”W], 750 m, 19-I-1964 (flr), H. Kruse 1380 (holotype: ENCB-002790-shoots bearing flowers only-image seen; isotypes (shoots bearing flowers only): EAP!, ENCB-002789!, FCME!, MEXU!, MICH!, MO!, US!) .

Shrubs to trees to 4 m tall. Older (woody) stems irregularly fissured-striate, lenticellate, lacking trichomes; younger (herbaceous) stems quadrate-sulcate, glabrous (or with the surface roughened but lacking trichomes). Leaves seasonally deciduous, clustered at branch apices (and appearing quadrate at some nodes), petiolate, petioles 20–90 mm long, blades apparently subsucculent, lanceolate to ovate to elliptic, 82–260 mm long, 35–110 mm wide, 2–2.6 × longer than wide, (rounded to) acuminate at apex, cuneate to subattenuate at base, abaxial surface minutely glandular-punctate (sometimes not evident) and sparsely pubescent (especially near base) with flexuose eglandular trichomes 0.2– 0.7 mm long or trichomes absent on mature leaves, adaxial surface very sparsely pubescent (if at all) with similar trichomes, margin entire to subsinuate, sparsely ciliate with trichomes like those of abaxial surface. Inflorescence a terminal sessile or pedunculate thyrse to 303 mm long (including peduncle, if present, and excluding corollas), peduncle (if present) to 52 (or more?) mm long, glandular-puberulent with glandular trichomes to 0.1 mm long, rachis pubescent with erect glandular trichomes 0.05– 0.2 mm long; dichasia opposite, pedunculate, mostly 1–3-flowered, to 50 (– 70 in fruit) mm long (excluding corollas), dichasial peduncles 6–14 (– 29 in fruit) mm long, pubescent like rachis. Bracts caducous (not seen). Bracteoles caducous (not seen). Flowers pedicellate, pedicels 23–30 (– 48 in fruit) mm long, pubescent like rachis. Calyx 5–9 mm long, lobes fused for 1–3. 5 mm at base, subheteromorphic, apparently subsucculent, abaxially pubescent with erect to flexuose glandular trichomes 0.05– 0.2 mm long, posterior lobe subconduplicate, broadly ovate to subtriangular, 3.5– 4.5 mm long, 3–4. 3 mm wide, sometimes smaller than lateral lobes, subacute to acute at apex, lateral lobes ovate to subtriangular, 4– 4.8 mm long, 3–4 mm wide, acute at apex. Corolla green and maroon-purple, 35–39 mm long, externally puberulent with erect glandular trichomes to 0.1 mm long, tube 17–30 mm long, narrow proximal portion 4. 5–9 mm long, 6–11 mm in diameter near midpoint, throat 11–20 mm long, 20–25 mm in diameter at mouth, lobes spreading to recurved, subtriangular to ovate, 10–13 mm long, 9–12 mm wide, rounded at apex. Stamens 4, 55–75 mm long, filaments glabrous (at least distally, proximal portion not seen), thecae 7. 5–8 mm long; staminode (if present) not seen. Style 80–82 mm long, glabrous, stigma 2-lobed, lobes ± funnelform, 1.5 mm long, shape and width not determined. Capsule 38–47 mm long, 4.7– 6 mm in diameter, pubescent throughout with erect glandular trichomes to 0.1 mm long, stipe 4 mm long. Seeds up to 24 per capsule, 4– 4.5 mm long, 3–4 mm wide, surfaces minutely granulate to ± scurfy.

PHENOLOGY.— Flowering: January; fruiting: January–March. Kruse 1380 noted that the flowers were “pronto caedizas,” possibly referring to their being soon deciduous during the day, and thus likely largely nocturnal.

DISTRIBUTION AND HABITAT.— Western Mexico (central Guerrero; Fig. 8 ); plants occur on limestone slopes in tropical subdeciduous forests (selva mediana subcaducifolia) at elevations near 750 m.

CONSERVATION.— Daniel (2017) discussed the rationale for and provided a preliminary conservation assessment of Data Deficient (DD) for L. rzedowskianum , which is known only from a single site.

ILLUSTRATIONS.— Rzedowski (1973:53, fig. 4).

DISCUSSION.— Daniel (2017) discussed the necessity for validating this name, its typification, and the sole collection locality.

ADDITIONAL SPECIMENS EXAMINED.— MEXICO. Guerrero: Mpio. Chilpancingo, Rincón de la Vía, cerca de Agua de Obispo , 9-VIII-1964 (vegetative) and 23-III-1963 (fruiting), H . Kruse 1380 ( EAP, ENCB, FCME, MEXU, MICH, MO, US) ; Mpio. Chilpancingo , Rincón de la Via, 27-I-1970, H . Kruse 2701 [catalog # 4755] ( MEXU); same locale, 14-VII-1970, H . Kruse 2701-b [catalog #5033] ( B, FCME, MEXU) .

Figures

FIGURE 8. Map of Mexico (showing states) and northern Central America with distributions of species of Louteridium endemic to Mexico: L. brevicalyx, L. dendropilosum, L. koelzii, L. parayi, L. rzedowskianum, and L. tamaulipense. Sym- bols may pertain to multiple collections.