Hilda León-Tejera

Some little known Hydrococcaceae (Cyanoprokaryota) from Central Mexico

The little known genera of Hydrococcaceae Cyanodermatium, Placoma and Hydrococcus are well represented in the epilithic and epiphytic flora of central Mexico. A new marine species of Cyanodermatium, C. gonzaliensis, is established and three freshwater populations of the genera Hydrococcus, Cyanodermatium and Placoma, that represent new records for Mexico are studied. The morphological characteristics of the development of the thalli in several species of the three genera from populations from both marine and continental habitats are described. These genera differ among each other, in the pattern of cell division and growth that result in a characteristic organization of the pseudofilaments and therefore in the shape of the colonies. The proposal made by KOMAREK & ANAGNOSTIDIS (1998) to separate these genera that do not produce baeocytes from those included in the family Hyellaceae to which they are similar in their pseudofilamentous organisation is supported.

Cyanobacteria and macroalgae from an arid environment mangrove on the east coast of the Baja California Peninsula

Abstract We describe the assemblage of cyanobacteria and macroalgae on Avicennia germinans pneumatophores, Rhizophora mangle aerial roots, and within the tidal channel of a mangrove located in a lagoon bordering the east coast of the Baja California Peninsula, from samples collected every 2 months from May 2005 to May 2006. A total of 68 species were found: 21 cyanobacteria, 1 Xanthophyta, 25 Chlorophyta, 1 Ochrophyta-Phaeophyceae, 19 Rhodophyta, and 1 Anthophyta. Species richness varied between habitats; pneumatophores supported 29 species of algae, aerial roots supported 20 species of algae, and the channel bottom supported 46 species. Taxa common to the three habitats were Lyngbya sp., Vaucheria sp., Boodleopsis pusilla, Rhizoclonium riparium, and Bostrychia radicans. Mean wet weight algal biomasses on aerial roots and in the channel were 494 g root-1and 12,924 g m-2, respectively. The dominant species on aerial roots and on the channel bottom were Caulerpa sertularioides, Gracilariopsis lemaneiformis, and Spyridia filamentosa. The channel bottom also had Vaucheria sp. and two cyanobacteria (Oscillatoria sp. and Lyngbya sp.). Morphotypes of two cyanobacteria (Heteroleibleinia sp. and Johanesbaptistia sp.) are recorded in this habitat for the first time.

Dermocarpella (Cyanoprokaryota / Cyanophyceae / Cyanobacteria) from the Pacific coast of Mexico

Abstract An account of the intricate history of the taxonomy and nomenclature of the genus Dermocarpella (Cyanobacteria / Cyanophyceae / Cyanoprokaryota) is provided. Detailed observations at the population level have allowed the detection of different stages of the life cycle of two species of this genus and have helped to solve some of the uncertainties in the validation of this genus. The species described are D. gardneri as a new name for Dermocarpa hemisphaerica Setchell et Gardner and Dermocarpella stellata sp. nov. An identification key and a comparative table of the diagnostic features of the species of the genus are included.

Tepoztequiella rhizoidea gen. et sp. nov. (Solieriaceae, Rhodophyta) from the Yucatan Peninsula, Mexico

Abstract: Molecular methods have greatly aided in discovering new diversity in many cryptic algal groups. Molecular-assisted species discovery has focused morphological analyses on previously overlooked taxa, leading to a better understanding of diversity and evolutionary patterns. The Yucatan Peninsula, as a junction of North and South American Atlantic floras, is very diverse and, while a well-explored area, continues to reveal new species. Our studies in this area have revealed a new cylindrical member of the Solieriaceae. Based on COI-5P, rbcL and RuBisCo spacer sequences, we show that this entity is phylogenetically unique. Its position in phylogenetic analyses, combined with morphological characters and the genetic divergence from other species and genera within the family, strongly supports the establishment of Tepoztequiella rhizoidea gen. & sp. nov. The diagnostic character of T. rhizoidea is the presence of many rhizoids arising from medullary filaments and from the cells of the inner cortex.

Taxonomy and life cycle of epiphytic Dermocarpellaceae and Xenococcaceae from central Mexico

In this paper we present a synthesis of several studies on the reproduction, life cyles and taxonomy of epiphytic baeocyte producing cyanoprokaryotes from central Mexico. We have found that thallus structure is closely related with the mechanism of reproduction (binary fission and/or multiple fission), planes of cell division during development and sheath consistency. We propose characteristics for distinguishing among species belonging to the genera. Xenococcus, Xenotholos, (Xenococcaceae), Cyanocystis, and Dermocarpella (Dermocarpellaceae).

Reproduction and baeocyte formation in two species of Dermocarpella (Cyanophyceae)

The reproductive stages of Dermocarpella gardneri and D. stellata, which have been reported only once, are described. Formation of baeocytes occurs by cellular divisions that are parallel to the substratum, followed by a series of anticlinal radial divisions. In some cases in D. gardneri, the superior cell, resulting from the first division parallel to the substratum, is liberated prior to radial divisions, and these probably represent the ‘macrogonidia’ originally described by Lemmermann for D. hemisphaerica. The baeocytes are released through a circular apical pore, which develops after the formation of a papilla that eventually dissolves to form a pore.

Two new species of Phyllonema (Rivulariaceae, Cyanobacteria) with an emendation of the genus

Two untapered, heterocytous species were observed and collected from the intertidal and supratidal zones of the Mexican coastline of the Pacific Ocean near Oaxaca and from the Gulf of Mexico. These populations were highly similar in morphology to the freshwater taxon Petalonema incrustans in the Scytonemataceae. However, 16S rRNA sequence data and phylogenetic analysis indicated that they were sister taxa to the epiphyllic, Brazilian species Phyllonema aveceniicola in the Rivulariaceae, described from culture material. While genetic identity between the two new species was high, they differed significantly in morphology, 16S rRNA gene sequence identity, and sequence and structure of the 16S–23S ITS region. Their morphology differed markedly from the generitype of the previously monotypic Phyllonema, which has tapered, heteropolar, single‐false branched trichomes with very thin or absent sheath. The two new species, Phyllonema ansata and Phyllonema tangolundensis, described from both culture and environmental material, have untapered, isopolar, geminately false branched trichomes with thick, lamellated sheaths, differences so significant that the species would not be placed in Phyllonema without molecular corroboration. The morphological differences are so significant that a formal emendation of the genus is required. These taxa provide a challenge to algal taxonomy because the morphological differences are such that one would logically conclude that they represent different genera, but the phylogenetic evidence for including them all in the same genus is conclusive. This conclusion is counter to the current trend in algal taxonomy in which taxa with minor morphological differences have been repeatedly placed in separate genera based primarily upon DNA sequence evidence.

Solieria incurvata (Solieriaceae, Rhodophyta), a new species from Venezuela based on morpho-anatomical and molecular evidence

Abstract Solieria incurvata from Puerto Escondido, Estado Falcon, Venezuela, is described as a new species based on morpho-anatomical and molecular data. Morphologically S. incurvata differs from other Solieria species, with which it shares its distributional range, by its narrow branches that become gradually constricted toward their bases, by possessing acute and incurved apices, and by its branching pattern and anatomical morphometrics. On the basis of COI-5P and rbcL sequences, the new species forms an independent lineage that clearly belongs in the Solieria clade of the Solieriaceae.