Chitons possess the most elaborate system of shell pores found in any hard-shelled invertebrate. Although chitons possess some anteriorly located sense organs, they lack true cephalization, as their major sensory systems are not concentrated in a distinct head region. Instead, the aesthete system within their shells forms a dense sensory network that overcomes the barrier of their hard dorsal armour.
View Article and Find Full Text PDFBackground: Discoveries of new species often depend on one or a few specimens, leading to delays as researchers wait for additional context, sometimes for decades. There is currently little professional incentive for a single expert to publish a stand-alone species description. Additionally, while many journals accept taxonomic descriptions, even specialist journals expect insights beyond the descriptive work itself.
View Article and Find Full Text PDFBackground: The genus can be easily distinguished from other chitons by having eighteen tufts of bristles on the dorsal side of the densely spiculose girdle. In the North-East Atlantic, five species of this genus have been recognised so far: (Pennant, 1777), (Brown, 1827), (Linnaeus, 1767), Leloup, 1968 and Schmidt-Petersen, Schwabe et Haszprunar, 2015. The nomenclature of , and was confused for a very long time until Kaas (1985) designated type specimens for them and provided a brief key.
View Article and Find Full Text PDFTaiwan lies at the transitional zone between the East Palaearctic and Oriental regions, which translates into both Palaearctic and Indomalayan taxa being present on the island. Furthermore, large habitat heterogeneity and high mountains contributed to the rise of conditions favouring allopatric speciation and the emergence of endemic species. The tardigrade fauna of Taiwan is poorly studied, and the aim of this contribution is to provide new data on the members of the family Echiniscidae, the largest limno-terrestrial group of the class Heterotardigrada, found at high elevations in central Taiwan.
View Article and Find Full Text PDFThere are two predominant sources of taxonomically useful morphological variability in the diverse tardigrade family Echiniscidae: the internal structure and surface sculpture of the cuticular plates covering the dorsum (sculpturing) and the arrangement and morphology of the trunk appendages (chaetotaxy). However, since the appendages often exhibit intraspecific variation (they can be reduced or can develop asymmetrically), sculpturing has been considered more stable at the species level and descriptions of new echiniscid species based solely on morphology are still being published. Here, we present a case study in which a detailed analysis of the morphology and multiple genetic markers of several species of the genus Viridiscus shows that cuticular sculpture may also exhibit considerable intraspecific variation and lead to false taxonomic conclusions.
View Article and Find Full Text PDFRecent years have brought undeniable progress in tardigrade taxonomy, and speciose complexes were detected in a number of phylogenetic lineages. The family Echiniscidae is one such lineage; it is one of the most diverse groups of limno-terrestrial tardigrades and can be characterized as having achieved great evolutionary success. In this contribution, using populations representing several species that originated from the Indomalayan region, we reconstructed phylogenetic affinities within Nebularmis, a recently erected genus within the Echiniscus lineage.
View Article and Find Full Text PDFTardigrades constitute a micrometazoan phylum usually considered as taxonomically challenging and therefore difficult for biogeographic analyses. The genus Pseudechiniscus, the second most speciose member of the family Echiniscidae, is commonly regarded as a particularly difficult taxon for studying due to its rarity and homogenous sculpturing of the dorsal plates. Recently, wide geographic ranges for some representatives of this genus and a new hypothesis on the subgeneric classification have been suggested.
View Article and Find Full Text PDFThe Afrotropical tardigrade fauna is insufficiently studied, and consequently its diversity in this region is severely underestimated. Ongoing sampling in the Udzungwa Mountains, Morogoro Region of Tanzania has revealed a new representative of the genus C.A.
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