A colonial ascidian of the genus Distaplia caused a mass mortality of the pen shell Atrina maura (Sowerby, 1835) during June 2016 in the southwest of the Gulf of California (Mexico), with a significant socio-economic cost. Tentatively identified in previous works as Distaplia cf. stylifera, a precise taxonomic determination was still lacking. In the present work, based on a detailed morphological study, it is confirmed that this aggressive species is Distaplia stylifera (Kowalevsky, 1874). Originally described from the Red Sea, the species currently has a wide circumtropical distribution (with the exception of the Eastern Pacific to date) and is reported as introduced in parts of its range. The present account thus represents an important range extension of this species. However, when revising the original description and later observations, the reported variability of several characters makes it likely that the binomen is in fact a complex of species, as is common in other ascidians with wide distributions. A complete morphological and genetic study including populations from the entire range of distribution would be necessary to settle the status of D. stylifera. Taxonomic uncertainties hinder a correct interpretation of biogeographical patterns and inference on the origin of the studied population. Nevertheless, the known introduction potential of the species, coupled with an explosive growth in an anthropized environment, and the lack of any previous reports in the Eastern Pacific, strongly suggest that the investigated population represents yet another instance of ascidian introduction. From the point of view of management, its invasive behavior is cause for great concern and warrants mitigation measures.

The sablefish Anoplopoma fimbria is distributed on the continental shelf of the North Pacific, has a high commercial value for both fisheries and aquaculture, and represents a shared resource between countries in the North Pacific basin. In the present study, we extend the geographic range surveyed in previous studies and reexamine the population’s genetic structure by integrating phylogeographic patterns of mitochondrial DNA and microsatellite DNA markers. Our results contradict the proposal that sablefish constitute a single population throughout their distributional range. We observed a signal of ancient divergence in mtDNA that differentiates the North Pacific West Coast from the rest of the sample sites, and microsatellite markers reveal a contemporary isolation of Mexican sablefish. Our findings show genetic differences between localities that should be explored in more detail to fully understand the interconnectedness that appears to exist between populations.

Twenty-one nominal species of Muricea have been reported in the Eastern Pacific with nine of them reported in the Mexican Pacific. We describe three new species of Muricea: Muricea ambarae sp. nov. and Muricea cacao sp. nov., from rocky reefs on the central and the northern Gulf of California and the Pacific coast of Baja California Sur, and Muricea molinai sp. nov., from the Pacific coast of Baja California Sur. Muricea ambarae sp. nov. and M. cacao sp. nov. are taxonomically allied to the nominal species Muricea fruticosa Verrill, 1869 due to the morphological similarity of colony growth patterns and the phylogenetic closeness based on the mitochondrial MutS gene (mtMutS); but differ mainly in the calyx form and composition of sclerites. The main morphological differences between the new Muricea species are in their sclerite forms and color; M. ambarae sp. nov. has orange-colored colonies, thin leaf spindles and tuberculated blunt spindles, while M. cacao sp. nov. has dark brown colored colonies, strong spinous spindles and an absence of tuberculated blunt spindles. Muricea molinai sp. nov. is phylogenetically close and morphologically similar to Muricea squarrosa Verrill, 1869 in the growth form of the colony and tubular calyces; but has dark brown colored colonies and has calyces from the base to the branch tips. With these three new species, the total number of Muricea species reported in the Mexican northwest region increases to twelve and a total of 24 nominal species in the Eastern Pacific.

Basil downy mildew, caused by the oomycete Peronospora belbahrii, can decrease whole basil crops in days, making it a top concern for basil growers. In this study, a Loop-Mediated Isothermal Amplification (LAMP)-based biosensor was developed for the rapid detection of P. belbahrii in Ocimum basilicum L. A fragment of a gene with unknown function was used as the target sequence to design primers for LAMP reactions. The optimal incubation temperature and time for the most efficient primer set were determined. Under standardized conditions, the LAMP assay exhibited at least 1000-fold higher sensitivity than conventional PCR, detecting attogram levels (1 copy) of synthetic DNA. Detection of the pathogen from genomic DNA (gDNA) of P. belbahrii spores confirmed the sensitivity of the assay. In terms of specificity, the LAMP assay showed negative results for gDNA from pathogenic fungi affecting basil and positive results for gDNA from diseased basil leaves. Finally, the LAMP assay could facilitate the rapid detection and diagnosis of basil downy mildew in infected tissues, providing information on basil health and, consequently, informing decisions regarding control management in O. basilicum fields.