ABSTRACT Background: Gracilaria parvispora is an invasive red seaweed located in coastal lagoons along the Tropical Mexican Pacific. Gracilaria species are the main source of agar around the world. Goals: Spatial and seasonal trends of the properties of native agar from the invasive seaweed G. parvispora were determined in three localities in the states of Oaxaca and Chiapas belonging to coastal lagoons along the Tropical Mexican Pacific: Ballenato, Paredón, and San Vicente. Methods: Native agar was obtained from dry samples of seaweed and the agar yield, gel strength, melting and gelling temperatures, hysteresis, and sulfate and 3,6-anhydrogalactose content were determined for each sample. Moreover, the polysaccharide structures and the location of sulfate groups in agar samples were identified. Results: The phycocolloid is a polysaccharide agar type. The agar yield was significantly different between seasons and localities, with the highest values during the dry season (19.9 ± 0.004%) at Paredón (20.6 ± 0.01 %). Gel strength, melting temperature and gel hysteresis showed significant spatial differences; the highest values were obtained in Ballenato (367.3 ± 14.2 g cm−2, 80.2 ± 1.4 °C, 44.3 ± 2.2 °C, respectively); gelling temperature did not show significant differences between localities or seasons. Chemical properties were significantly different between seasons: 3,6-anhydrogalactose content was higher during the dry season (36.2 ± 0.2 %), and sulfate content was higher during the rainy season (12.69 ± 0.21 %). Salinity was significantly different between seasons, and the highest was obtained during the dry season (38.7 ± 0.1). Surface water temperature varied between localities, and the highest mean value was recorded at Paredón (32.5 ± 0.2 °C.( Conclusions: The chemical properties of the G. parvispora native agar were lower than the standards for food and industrial use.

RESUMEN Antecedentes: Gracilaria parvispora es un alga roja invasora que se encuentra en lagunas costeras del Pacífico Mexicano Tropical. A nivel mundial, las especies de Gracilaria son la fuente principal de agar. Objetivos: Se determinaron las tendencias espaciales y temporales de las propiedades del agar nativo de G. parvispora en tres localidades de los estados de Oaxaca y Chiapas, pertenecientes a lagunas costeras del Pacífico Mexicano Tropical: Ballenato, Paredón y San Vicente. Métodos: Se determinó el rendimiento del agar, la fuerza de gel, la temperatura de fusión y gelificación, la histéresis, y el contenido de sulfatos y 3,6-anhidrogalactosa del agar nativo obtenido de muestras secas de macroalga. Además, se identificaron las estructuras de los polisacáridos y la posición de los grupos sulfato en las muestras. Resultados: El ficocoloide es un polisacárido tipo agar. El rendimiento mostró diferencias significativas entre localidades y temporadas, con valores mayores durante la temporada de secas (19.9 ± 0.004%) y en Paredón (20.6 ± 0.01 %). La fuerza de gel, la temperatura de fusión y la histéresis mostraron diferencias espaciales significativas; con valores más altos para las muestras de Ballenato (367.3 ± 14.2 g cm−2, 80.2 ± 1.4 °C, 44.3 ± 2.2 °C, respectivamente); la temperatura de gelificación no mostró diferencias significativas entre localidades o temporadas. Las propiedades químicas mostraron diferencias significativas entre temporadas: el contenido de 3,6-anhidrogalactosa fue mayor durante la temporada de secas (36.2 ± 0.2 %), y el contenido de sulfato fue mayor durante la temporada de lluvias (12.69 ± 0.21 %). La salinidad fue significativamente diferente entre temporadas, con mayor valor para la temporada de secas (38.7 ± 0.1). La temperatura superficial del agua varió entre localidades, la más alta se registró en Paredón (32.5 ± 0.2 °C.) Conclusiones: Las propiedades químicas de G. parvispora fueron menores a los estándares para su uso industrial y alimenticio.

Here, we describe the development of sporangial and gametangial conceptacles for Amphiroa beauvoisii and A. vanbosseae; sporangial conceptacles only for A. misakiensis; and gametangial conceptacles only for A. cryptarthrodia and A. rigida. The descriptions are based on the observation of histological preparations obtained from 112 specimens collected from the Gulf of California, in Mexico, and the Azores archipelago of Portugal. Information on the development of the sporangial conceptacle pore and conceptacle senescence is here described and illustrated for the first time. Four development patterns were observed: two for sporangial conceptacles; one for spermatangial conceptacles; and one for carposporangial conceptacles. The phases of development of the sporangial conceptacle were found to be useful in delimiting species within the genus. Based on the sporangium location on the cavity floor and the pore canal anatomy, the species A. beauvoisii, A. misakiensis and A. vanbosseae can be distinguished from each other.