18S rRNA variability maps reveal three highly divergent, conserved motifs within Rotifera

Proalesamplus sp. nov., a new monogonont rotifer with a large epipharynx from Korea (Rotifera, Proalidae)

Background

The family Proalidae Harring & Myers, 1924, includes four genera and 53 species, distributed across all eight biogeographic realms and inhabiting various environments, including freshwater, saltwater and terrestrial environments. The genus Proales, the largest within Proalidae, encompasses 41 species characterised by diverse morphological traits. In Korea, the presence of Proalidae has been documented with five known species: Bryceellaperpusilla Wilts, Martínez Arbizu & Ahlrichs, 2010, B.stylata (Milne, 1886), B.tenella (Bryce, 1897), Proalesfallaciosa Wulfert, 1937 and Proalinopsiscaudatus (Collins, 1872).

New information

A new species, Proalesamplus sp. nov., is the 42nd species within the genus Proales. This species exhibits unique morphological characteristics in the trophi, particularly in the epipharynx, which are distinctive enough to prevent misidentification with other Proales species. The habitus of the new species bears some resemblance to P.phaeopis Myers, 1933, sharing features, such as an elongated and fusiform body, two eyespots, a single foot pseudosegment, two short toes and the absence of a dorsal papilla between the toes. However, the epipharynx of the two species is markedly different. The unique epipharynx characteristic of this new species is unparalleled within the genus Proales.

Diversification of the shell shape and size in Baikal Candonidae ostracods inferred from molecular phylogeny

Ostracod shells are used extensively in paleontology, but we know little about their evolution, especially in ancient lakes. Lake Baikal (LB) is the world's most important stronghold of Candonidae diversity. These crustaceans radiated here rapidly (12-5 Ma) and with an unprecedented morphological diversity. We reconstruct their molecular phylogeny with 46 species and two markers (18S and 16S rRNA), and use it to estimate the evolution of the shell shape and size with landmark-based geometric morphometrics (LBGM). High posterior probabilities support four major clades, which differ in node depth and morphospace clustering. After removing a significant allometry, the first three principal components (PCs) describe about 88% of total variability, suggesting a strong integration. Reconstructed ancestral shapes are similar for all four clades, indicating that diversification happened after colonization. Major evolutionary changes occurred from trapezoidal to elongated shapes. Sister species are separated in morphospace, by centroid size, or both, as well as by vertical and horizontal distributions in LB. Ostracod shell is a strongly integrated structure that exhibits high evolvability, with some extreme shapes, although mostly along the first PC. This is the first study that combines molecular phylogeny and LBGM for ostracods and for any LB group.

About the Analysis of 18S rDNA Sequence Data from Trypanosomes in Barcoding and Phylogenetics: Tracing a Continuation Error Occurring in the Literature

The variable regions (V1–V9) of the 18S rDNA are routinely used in barcoding and phylogenetics. In handling these data for trypanosomes, we have noticed a misunderstanding that has apparently taken a life of its own in the literature over the years. In particular, in recent years, when studying the phylogenetic relationship of trypanosomes, the use of V7/V8 was systematically established. However, considering the current numbering system for all other organisms (including other Euglenozoa), V7/V8 was never used. In Maia da Silva et al. [Parasitology 2004, 129, 549–561], V7/V8 was promoted for the first time for trypanosome phylogenetics, and since then, more than 70 publications have replicated this nomenclature and even discussed the benefits of the use of this region in comparison to V4. However, the primers used to amplify the variable region of trypanosomes have actually amplified V4 (concerning the current 18S rDNA numbering system).