Water bear with barbels of a catfish : a new Asian Cornechiniscus (Heterotardigrada: Echiniscidae) illuminates evolution of the genus

Cornechiniscus Maucci & Ramazzotti, 1981 is a species-poor heterotardigrade genus with peculiar, horn-shaped appendages A. It can be found in mosses and lichens growing on dusty soils on all continents except for Australasia and Antarctica, with presumably Central Asia as the main place of species radiation. A recent, COI and ITS-1-based phylogeny elucidated phylogenetic relationships between 5 out of 10 Cornechiniscus species, and aided the integrative description of C. imperfectus Gąsiorek & Michalczyk, 2020 from mountains of Northern Kyrgyzstan. However, the other 5 species remained unplaced on the generic evolutionary tree. Using new samples from Northern Kyrgyzstan, Italy and Argentina, I extracted new representatives of the genus and updated the genus phylogeny in the frame of integrated taxonomic approach (light and scanning microscopy, DNA sequencing of four markers: 18S rRNA, 28S rRNA, ITS-1, and COI). A new Kyrgyz species is dioecious and necessitates modifying the genus diagnosis to accommodate its cirri prolongation that contrasts with bulbous peribuccal cirri typical for Cornechiniscus. Furthermore, it enhances the hypothesis on the Central Asian origin of the genus. Morphologically, C. mystacinus sp. nov. most closely resembles C. tibetanus (Maucci, 1979) by its large body size (adult females ~500 μm on average), strongly heteronych and smooth claws, and by the development of spines in the lateral positions C–E and at the posterior margin of the pseudosegmental plate IV’. I demonstrated the sister relationship between C. holmeni (Petersen, 1951) and C. imperfectus, previously hypothesised based on their morphological similarity. Cornechiniscus lobatus (Ramazzotti, 1943) can be considered a subcosmopolitan taxon since it certainly occurs in the Holarctic and Neotropics

Feeding strategies and competition between terrestrial Haemadipsa leeches (Euhirudinea : Arhynchobdellida) in Danum Valley rainforest (Borneo, Sabah)

Haemadipsid leeches are among the most successful terrestrial invertebrates in Bornean rainforests. They are very common ectoparasites of vertebrates, and their abundance has facilitated the conduction of numerous projects in the fields of ecology, zoogeography and taxonomy. We undertook research on two species inhabiting lowland dipterocarp forest, Haemadipsa picta Moore, 1929 and Haemadipsa subagilis (Moore, 1929), in order to address the following questions: (a) is there a difference in leech abundance between trails and off-trails?; (b) is ambush location dependent on specimen size or is species-specific?; (c) is intra- and interspecific competition limited by differences in foraging behaviours or vertical niche partitioning? Our results clearly show that H. picta is more abundant on trails than on off-trails and is vertically dispersed within the understory; the size of a specimen is strongly correlated with plant height. Haemadipsa subagilis was found not to exhibit such patterns. We suggest a possible lowering of interspecific competition between these species as a result of: (i) size-dependent dispersion of H. picta (together with reduction of intraspecific competition); and (ii) habitat specialisation of H. subagilis. Moreover, we provide new observations on their foraging behaviour

New Echiniscidae (Heterotardigrada) from Amber Mountain (Northern Madagascar)

A moss sample from the local biodiversity hotspot in lowland rainforest in the vicinity of Amber Mountain, Madagascar, yielded the discovery of two Echiniscus C.A.S. Schultze, 1840 species, of which one is new to science. Echiniscus succineus sp. nov. is related to other members of the spinulosus group, but differs from them by the highly complicated structure of the dorsal plates, with intricately thickened parts of the armour forming ornamented pattern. The validity of the intraporal dark rings as a taxonomic trait is discussed in the context of the recovered intraspecific variability for the new taxon. Besides, rare Echiniscus africanus Murray, 1907 is reported for the first time from the island

New Echiniscidae (Heterotardigrada) from Amber Mountain (Northern Madagascar)

A moss sample from the local biodiversity hotspot in lowland rainforest in the vicinity of Amber Mountain, Madagascar, yielded the discovery of two Echiniscus C.A.S. Schultze, 1840 species, of which one is new to science. Echiniscus succineus sp. nov. is related to other members of the spinulosus group, but differs from them by the highly complicated structure of the dorsal plates, with intricately thickened parts of the armour forming ornamented pattern. The validity of the intraporal dark rings as a taxonomic trait is discussed in the context of the recovered intraspecific variability for the new taxon. Besides, rare Echiniscus africanus Murray, 1907 is reported for the first time from the island

New marine heterotardigrade lineages (Echiniscoididae) from the tropics

Echiniscoididae are the only family of the clade Echiniscoidea residing in marine habitats. Their characteristic feature is the multiplication of claws on legs, commonly regarded as an adaptation to unstable tidal environment. Although DNA barcoding data indicated the presence of numerous unnamed candidate species within Echiniscoides about a decade ago, only recently have new species been formally described. In this paper, we present new genetic, morphological and morphometric data and establish five Echiniscoides species found in samples acquired from various tropical regions: Echiniscoides basalticus sp. nov. (Mauritius, Indian Ocean), Echiniscoides bufocephalus sp. nov. (Qatar, Indian Ocean), Echiniscoides lichenophilus sp. nov. (Dominican Republic, Atlantic Ocean), Echiniscoides musa sp. nov. (Brazil, Atlantic Ocean), and Echiniscoides trichosus sp. nov. (Rapa Nui, Pacific Ocean). We discuss the taxonomic importance of cuticular sculpturing in Echiniscoididae. Finally, we elevate all subspecies of Echiniscoides sigismundi to species level. The key to all echiniscoidids is provided

Pseudechiniscus in Japan : re-description of "Pseudechiniscus asper" Abe et al., 1998 and description of Pseudechiniscus shintai sp. nov.

The classification and identification of species within the genus Pseudechiniscus Thulin, 1911 has been considered almost a Sisyphean work due to an extremely high homogeneity of its members. Only recently have several contributions made progress in the taxonomy feasible through their detailed analyses of morphology and, crucially, by the re-description of the ancient, nominal species P. suillus (Ehrenberg, 1853). Herein, we focus on the Japanese representatives of this genus: P. asper, a rare species originally described from Hokkaido, and a new species P. shintai. Both taxa belong to the widespread suillus-facettalis complex. Detailed descriptions entailing DNA barcoding of four markers and illustrations of the ventral pillar patterns are indispensable for an accurate delineation of species within this genus

Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada: Halechiniscidae)

Secondary sexual dimorphism in florarctin tardigrades is a well-known phenomenon. Males are usually smaller than females, and primary clavae are relatively longer in the former. A new species Florarctus bellahelenae, collected from subtidal coralline sand just behind the reef fringe of Long Island, Chesterfield Reefs (Pacific Ocean), exhibits extreme secondary dimorphism. Males have developed primary clavae that are much thicker and three times longer than those present in females. Furthermore, the male primary clavae have an accordion-like outer structure, whereas primary clavae are smooth in females. Other species of Florarctus Delamare-Deboutteville & Renaud-Mornant, 1965 inhabiting the Pacific Ocean were investigated. Males are typically smaller than females, but males of Florarctus heimi Delamare-Deboutteville & Renaud-Mornant, 1965 and females of Florarctus cervinus Renaud-Mornant, 1987 have never been recorded. The Renaud-Mornant collection was re-examined, and type series were analysed. Florarctus heimi and F. cervinus were always found together in the coralline sand of Heron Island (Great Barrier Reef). The animals were kept alive and surveyed in the laboratory of the Queensland Museum. All studied individuals of the larger F. heimi (up to ca. 400 μm) were females, and all adults of the smaller F. cervinus (about 170 μm) were males. Males of F. cervinus were observed mating with females of F. heimi. Following those morphological and behavioural lines of evidence, we propose that F. cervinus is a junior synonym of F. heimi. Based on the discovery of dimorphism in F. bellahelenae sp. nov. and the strong sex-related morphological disparities in F. heimi, we suggest that extreme secondary dimorphism may be present in other florarctin arthrotardigrades

Phylogeography and morphological evolution of Pseudechiniscus (Heterotardigrada: Echiniscidae)

Tardigrades 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. In order to test these hypotheses, we sequenced 65 Pseudechiniscus populations extracted from samples collected in 19 countries distributed on 5 continents, representing the Neotropical, Afrotropical, Holarctic, and Oriental realms. The deep subdivision of the genus into the cosmopolitan suillus-facettalis clade and the mostly tropical-Gondwanan novaezeelandiae clade is demonstrated. Meridioniscus subgen. nov. is erected to accommodate the species belonging to the novaezeelandiae lineage characterised by dactyloid cephalic papillae that are typical for the great majority of echiniscids (in contrast to pseudohemispherical papillae in the suillus-facettalis clade, corresponding to the subgenus Pseudechiniscus). Moreover, the evolution of morphological traits (striae between dorsal pillars, projections on the pseudosegmental plate IV’, ventral sculpturing pattern) crucial in the Pseudechiniscus taxonomy is reconstructed. Furthermore, broad distributions are emphasised as characteristic of some taxa. Finally, the Malay Archipelago and Indochina are argued to be the place of origin and extensive radiation of Pseudechiniscus

Deceptive conservatism of claws : distinct phyletic lineages concealed within Isohypsibioidea (Eutardigrada) revealed by molecular and morphological evidence

Isohypsibioidea are most likely the most basally branching evolutionary lineage of eutardigrades. Despite being second largest eutardigrade order, phylogenetic relationships and systematics within this group remain largely unresolved. Broad taxon sampling, especially within one of the most speciose tardigrade genera, Isohypsibius Thulin, 1928, and application of both comparative morphological methods (light contrast and scanning electron microscopy imaging of external morphology and buccal apparatuses) and phylogenetic framework (18S + 28S rRNA sequences) resulted in the most comprehensive study devoted to this order so far. Two new families are erected from the currently recognised family Isohypsibiidae: Doryphoribiidae fam. nov., comprising all aquatic isohypsibioids and some terrestrial isohypsibioid taxa equipped with the ventral lamina; and Halobiotidae fam. nov., secondarily marine eutardigrades with unique adaptations to sea environment. We also split Isohypsibius into four genera to accommodate phylogenetic, morphological and ecological variation within the genus: terrestrial Isohypsibius s.s. (Isohypsibiidae), with smooth or sculptured cuticle but without gibbosities; terrestrial Dianea gen. nov. (Isohypsibiidae), with small and pointy gibbosities; terrestrial Ursulinius gen. nov. (Isohypsibiidae), with large and rounded gibbosities; and aquatic Grevenius gen. nov. (Doryphoribiidae fam. nov.), typically with rough cuticle and claws with branches of very similar heigths. Claw morphology is reviewed and, for the first time, shown to encompass a number of morphotypes that correlate with clades recovered in the molecular analysis. The anatomy of pharynx and cuticle are also shown to be of high value in distinguishing supraspecific taxa in Isohypsibioidea. Taxonomy of all isohypsibioid families and genera is discussed, with special emphasis on the newly erected entities. Finally, a dychotomous diagnostic key to all currently recognised isohypsibioid families and genera is provided

Small is beautiful : the first phylogenetic analysis of Bryodelphax Thulin, 1928 (Heterotardigrada, Echiniscidae)

The phyletic relationships both between and within many of tardigrade genera have been barely studied and they remain obscure. Amongst them is the cosmopolitan Bryodelphax, one of the smallest in terms of body size echiniscid genera. The analysis of newly-found populations and species from the Mediterranean region and from South-East Asia gave us an opportunity to present the first phylogeny of this genus, which showed that phenotypic traits used in classical Bryodelphax taxonomy do not correlate with their phyletic relationships. In contrast, geographic distribution of the analysed species suggests their limited dispersal abilities and seems to be a reliable predictor of phylogenetic affinities within the genus. Moreover, we describe three new species of the genus. Bryodelphax australasiaticus sp. nov., by having the ventral plate configuration VII:4-4-2-4-2-2-1, is a new member of the weglarskae group with a wide geographic range extending from the Malay Peninsula through the Malay Archipelago to Australia. Bryodelphax decoratus sp. nov. from Central Sulawesi (Celebes) also belongs to the weglarskae group (poorly visible ventral plates VII:4-2-2-4-2-2-1) and is closely related to the recently described Bryodelphax arenosus Gąsiorek, 2018, but is differentiated from the latter by well-developed epicuticular granules on the dorsum. Finally, a new dioecious species, Bryodelphax nigripunctatus sp. nov., is described from Mallorca and, by the reduced ventral armature (II/III:2-2-(1)), it resembles Bryodelphax maculatus Gąsiorek et al., 2017. The latter species, known so far only from northern Africa, is recorded from Europe for the first time. A taxonomic key to the genus members is also presented