DANIEL & TRIPP: LOUTERIDIUM : TAXONOMY, BIOLOGY, AND CONSERVATION 101 
rocky limestone slopes in “tropical semi-evergreen and evergreen forest” (Richardson 1972) at 
elevations from 340 to 560 (to 1400) meters. The vegetation at collection sites has been character¬ 
ized on specimen labels as wet forest, cloud forest, and “selva mediana subperennifolia.” 
Conservation. — Louteridium tamaulipense is a local endemic that is known in the vicinity 
of the Sierra de Guatemala (= Sierra de Cucharas) in the northern Sierra Madre Oriental of 
Tamaulipas, where its known distribution (EOO = 43 km 2 ) is confined to the Reserva de la Bios- 
fera El Cielo. Valiente B. et al. 285 noted that the species was locally very abundant. Several threats 
have been noted for the biosphere reserve, including: unplanned agricultural and forestry exploita¬ 
tion still being undertaken, overgrazing by livestock, increases in population density in surround¬ 
ing buffer zones, poorly regulated eco-tourism, and poaching (Anonymous 2007). Most (or all?) of 
the collections have been made in the buffer zones outside of the two core areas (in which most 
human travel and exploitation are prohibited) of the reserve. The buffer zones, including the EOO, 
include roads, villages, and tourist facilities. However, historical landsat images (2005 to 2016) via 
Google Earth Pro (2018) reveal relatively little change in vegetation cover in the EOO. Thus, based 
on current knowledge of the species, it is not known to qualify for a threatened category in spite of 
its very small EOO. Based on the information summarized above, the species is provisionally 
assessed as Near Threatened (NT). 
Discussion. — Richardson’s (1972) observations on floral phenology and visitation are very 
similar to those noted above for L. dendropilosum in Oaxaca. Louteridium tamaulipense shows 
some similarities to L. costaricense, and can be distinguished from that species of southern Central 
America by characters in the following couplet: 
la. Corolla externally pubescent with glandular trichomes 0.1-0.5 mm long and eglandular 
trichomes 0.1-1 mm long, lower lip 13-22 mm long; capsule 27-35 mm long, glabrous, stipe 
7-12 mm long; inflorescence peduncles, rachis, peduncles of dichasia, and abaxial surface of 
bracts and bracteoles glabrous (or the bracts and bracteoles sometimes glandular-punctate but 
lacking elongate trichomes); bracts and bracteoles persistent. L. costaricense 
lb. Corolla externally puberulent with glands to 0.1 mm long, lower lip 27-31 mm long; capsule 
22-25 mm long, pubescent with glandular trichomes 0.05-0.2 mm long, stipe 1—4 mm long; 
inflorescence peduncles, rachis, peduncles of dichasia, and abaxial surface of bracts and bracte¬ 
oles pubescent with glandular trichomes 0.1-0.3 mm long; bracts and bracteoles caducous . .. 
. L. tamaulipense 
Additional specimens examined.— MEXICO. Tamaulipas: Mpio. Gomez Farias, 1 km 
SW de la Estacion Canindo (sitio Cedros II), [ca. 23°02’23.25”N, 099°13’59.36”W], L. Hernan¬ 
dez 3022 (BRIT, QMEX); 8 km por la brecha W de Gomez Farias [ca. 23°02’43.51”N, 
099°10’09.65”W], E. Martinez S. et al. 3854 (ENCB, MEXU); ca. 5 km NW of Gomez Farias, 
A. Richardson 1398 (K); Mpio. Gomez Farias, 1.5 km E de Gomez Farias, laderas de orientacion 
WSW sobre la Sierra Chiquita [ca. 23°02’48.23”N, 099°08’26.35”W], A. Valiente B. 490 (MEXU); 
Mpio Gomez Farias, 2 km W de Gomez Farias, postrimerias de la Sierra Madre Oriental, 
A. Valiente B. et al. 285 (ARIZ, MEXU, RSA); Mpio. Gomez Farias, 1.5 km E de Gomez Farias, 
ladera de orientacion W sobre la “Sierra Chiquita,” A. Valiente B. et al. 443 (MEXU). Cultivated: 
University of California Botanical Garden (acc. no. 60.889-1), grown from plants collected by 
R. Dressier ( s.n .) in Tamaulipas, above Encino, on road to lumber camp Julillo [ca. 23°07’37.45”N, 
099°09’45.46”W], P. Hutchison 60-889-1 (UC). 
