DANIEL: NEW AND RECONSIDERED MEXICAN ACANTHACEAE XII 
135 
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 Rio Lagartos). Although human population pressures and 
climatic changes will impact (either negatively or positively?) the distribution and numbers of indi¬ 
viduals 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. Yucatan: alrededores de la zona arqueologica de Mayapan, 1 km S 
de Telchaquillo, earn 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-Rio 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, earn a Tunkas, ca. 20°54 f N, 88°50.5'W, G. Carnevali et 
al. 4381 (CICY); Mpio. Rio Lagartos, entre el camino Rio Lagartos rumbo a Las Coloradas, 
21°34'N, 88°10'W, C. Chan 4796 (CICY); Mpio. Rio Lagartos, camino de Rio Lagartos rumbo a 
Las Coloradas, 21°36.5'N, 88°03'W, C. Chan 4809 (CICY); Mpio. Sucila, along hwy. 176 between 
Buctzotz and Sucila (27 km W of Sucila), 21°10.5'N, 088°28.8'W, 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 Carlowrigh- 
tia yucatanensis from the Yucatan Peninsula as a third distinctive population of C. hintonii T.F. 
Daniel. Since then, reexamination of materials from these populations reveals that the morpholog¬ 
ical distinctions of plants from the Yucatan Peninsula are more reflective of a distinct species than 
a variant of C. hintonii. The following key summarizes distinctions between them. 
la. 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; bracte- 
oles (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 Sal¬ 
vador, capsules all or chiefly eglandular); Pacific versant with plants occurring at elevations at 
or above 380 m.C. hintonii 
lb. 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°; bracte- 
oles (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 medium¬ 
sized butterflies, honey bees, and smaller bees or flies. Corollas began dehiscing and falling in light 
winds at 13:45, which confor m s 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 rel- 
