Taxonomic and Photographic Guide to the Acanthaceae of Tamaulipas, Mexico Author Daniel, Thomas F. Department of Botany, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, California 94118, U. S. A. tdaniel@calacademy.org Author García-Morales, Leccinum J. Herbario, Departamento de Posgrado e Investigación, Instituto Tecnológico de Ciudad Victoria, Blvd. Emilio Portes Gil 1301, Cd. Victoria, Tamaulipas, México; Author Mora-Olivo, Arturo Instituto de Ecología Aplicada, Universidad Autónoma de Tamaulipas, División del Golfo 356, Cd. Victoria 87019, Tamaulipas, México; text Proceedings of the California Academy of Sciences 2021 2021-09-30 67 6 185 228 journal article 10.5281/zenodo.11513051 0068-547X 11513051 Louteridium tamaulipense A. Richardson PHENOLOGY .— Flowering: January–June, September, December; fruiting: March–April, September. DISTRIBUTION .— Mexico (Tamps.). HABITAT .— Tropical deciduous forest, tropical evergreen forest, cloud forest, on limestone. ELEVATION .— 340–560 (–1400) meters. NOTES .— Daniel and Tripp (2018) provided a description of Louteridium tamaulipense ( Fig 3D ), which is endemic to Tamaulipas . Its occurrences in the state represent, by ca. 500 kilometers, the northernmost extent of the genus. With an EOO of 23 km 2 and an AOO of 24 km 2 this species could potentially be assessed as either critically endangered (CR) or endangered (EN) if threats were to be identified ( IUCN 2019 ). REPRESENTATIVE SPECIMENS .— Mpio. Gómez Farías , 1 km SW de la Estación Canindo (sitio Cedros II ), [23.050000°, -99.150000°], L. Hernández 3022 ( BRIT , QMEX , UAT ) ; cultivated from plants collected above Encino , on rd. to lumber camp Julillo [ca. 23.127069°, -99.162620°], P. Hutchison 60-889-1 ( UC ) ; 8 km por la brecha W de Gómez Farías [ca. 23.045419°, -99.169347°], E. Martínez S. et al. 3854 ( ENCB , MEXU ) ; ca. 5 km NW of Gómez Farías toward Aguacates [ca. 23.063313°, -99.168914°], A. Richardson 1388 ( holotype : TEX !, mounted on 4 sheets; isotypes : ENCB-image !, F !, GH , K !, MEXU !, MICH !, NY !, OS-image , UC !, US !, WIS-images ) ; ca. 5 km NW of Gómez Farías , [ca. 23.083517°, -99.184750°], A. Richardson 1398 ( K ) ; Mpio Gómez Farías , 2 km W de Gómez Farías, postrimerias de la Sierra Madre Oriental , [23.048044°, - 99.174054°], A. Valiente B. et al. 285 ( ARIZ , MEXU , RSA ) ; Mpio. Gómez Farías , 1.5 km E de Gómez Farías, ladera de orientación W sobre la “ Sierra Chiquita ,” [23.047383°, -99.140541°], A. Valiente B. et al. 443 ( MEXU ) ; Mpio. Gómez Farías , 1.5 km E de Gómez Farías, laderas de orientación WSW sobre la Sierra Chiquita [ca. 23.046731°, -99.140653°], A. Valiente B. et al. 490 ( MEXU ) .