Taxonomy and distribution of Paralemanea (Lemaneaceae, Rhodophyta) in Central Mexico

Three collections of Paralemanea from Central Mexico included two species. Paralemanea mexicana is large (length ≥ 4.0 cm; diameter > 400 μm) and generally branched (≥ 40 % of plants branched), with whorled branches, of first to second order. Paralemanea annulata is small (length < 5.0 cm ; diameter < 500 μm), generally unbranched (≤ 5 % of plants branched), with branches of first order. Spermatangial sori contained obovoid spermatangia, formed from cells of the outer cortical layers, extending above the thallus surface. Carpogonial branches are described for the first time in P. mexicana. They develop on lateral filaments at nodes or internodes and have ovoid to globular cells, abundantly branched at the basal portion, penetrating the cortex towards the thallus surface. Carposporophytes are sessile on the inner portion of the cortex and produce carpospores in chains of up to twelve. The 'Chantransia' stage was observed in P. mexicana. Paralemanea annulata is described for the first time from Mexico and P. mexicana is endemic from this country. Both species were collected in cold (temperature 12-16°C), acidic (pH 5.5-6.0), shallow (depth 1-60 cm) and moderate to fast flowing waters (> 35 cm s-1), in shaded or partly shaded river segments, on rocky substrata (mostly bedrock).

Taxonomy of the Lemaneaceae (Batrachospermales, Rhodophyta) in China

Six species, belonging to two genera of Lemaneaceae in China are described. They are Lemanea Bory (including L. sinica Jao, L. crassa S. L. Xie et Z. X. Shi, L. ramosa S. L. Xie et Z. X. Shi and L. simplex Jao) and Paralemanea (Silva) Vis et Sheath (including P catenata (Kutzing) Vis et Sheath and P. parvula (Sirodot) S. L. Xie et Z. X. Shi). Among them L. crassa S. L. Xie et Z. X. Shi and L. ramosa S. L. Xie et Z. X. Shi are new species. Moreover, Paralemanea (Silva) Vis et Sheath and P. catenata (Kutzing) Vis et Sheath, P. parvula (Sirodot) S. L. Xie et Z. X. Shi are newly recorded in China.

Somatic meiosis and development of the juvenile gametophyte in members of the Batrachospermales sensu lato (Rhodophyta)

Seven populations (six in culture and one sampled directly from nature) of the freshwater red algal families Batrachospermaceae, Lemaneaceae and Thoreaceae were examined, involving three species of Batrachospermum, two of Paralemanea and one of Thorea. All 'Chantransia' stages ultimately produced juvenile gametophytes. The production of juvenile gametophytes in the three populations of Batrachospermum was generally most abundant at 15°C and low irradiances (47-68 μmol photons m-2 s-1). The most abundant gametophyte development in the Paralemanea species was observed at 10°C and low or high irradiances (47-142 μmol photons m-2 s-1). Gametophyte production in Thoreaceae occurred at higher temperatures (20°C) and also at low irradiances. In species of the Batrachospermaceae and Lemaneaceae, the 'elimination cells' can be situated on the basal or suprabasal cell of the juvenile gametophyte, but the position is usually fixed in individual species. The presence and position of the elimination cells remain to be established in Thoreaceae. Our results corroborate a previous study suggesting that the position of elimination cells is such a constant feature that it is of potential diagnostic value at the generic or infrageneric (sectional or specific) level. The characteristics observed in the development of the juvenile gametophytes in species of Batrachospermaceae and Lemaneaceae essentially agreed with general descriptions in the previous studies. The characteristics of the Thoreaceae, with a distinctive developmental pattern of the juvenile gametophyte and the occurrence of two morphological types in the 'Chantransia' stage, support the proposal to elevate it to the ordinal level. Two remarkable observations in Batrachospermum species were the production of numerous juvenile gametophytes from filaments of the same plant of the 'Chantransia' stage and the formation of a system of rhizoidal filaments or cell agglomeration of the juvenile gametophytes, which produced new gametophytes. These two characteristics potentially increase the formation of additional gametophytes under favourable conditions.