Mitogenome selection in the evolution of key ecological strategies in the ancient hexapod class Collembola.

A longstanding question in evolutionary biology is how natural selection and environmental pressures shape the mitochondrial genomic architectures of organisms. Mitochondria play a pivotal role in cellular respiration and aerobic metabolism, making their genomes functionally highly constrained. Evaluating selective pressures on mitochondrial genes can provide functional and ecological insights into the evolution of organisms. Collembola (springtails) are an ancient hexapod group that includes the oldest terrestrial arthropods in the fossil record, and that are closely associated with soil environments. Of interest is the diversity of habitat stratification preferences (life forms) exhibited by different species within the group. To understand whether signals of positive selection are linked to the evolution of life forms, we analysed 32 published Collembola mitogenomes in a phylomitogenomic framework. We found no evidence that signatures of selection are correlated with the evolution of novel life forms, but rather that mutations have accumulated as a function of time. Our results highlight the importance of nuclear-mitochondrial interactions in the evolution of collembolan life forms and that mitochondrial genomic data should be interpreted with caution, as complex selection signals may complicate evolutionary inferences.

Checklist of the springtails (Hexapoda: Collembola) of the Edough massif, northeastern Algeria.

Based on 225 samples taken from different biotopes in the Edough Massif (northeastern Algeria) from 1998 to 2018, we compiled a list of 91 collembolan species names from the literature, of which 72 can be considered valid records. Fourteen of them are only known from this massif in Algeria, and eight are endemic of northeastern Algeria. These 72 species are spread over 14 families and 49 genera. The family Neanuridae is the most diverse with 18 species, including six species of the genus Friesea. The monotypic genus Edoughnura (Neanurinae) is endemic to the Edough and Collo massifs. Several of the listed species do not fully match the diagnosis of the species to which they have been assigned and may represent undescribed taxa. Entomobryidae as well as several habitats (epigean, deep soil, littoral) remain unsampled or undersampled in Edough, and are likely to host many more species than those listed in this paper.

Unusually low genetic divergence at COI barcode locus between two species of intertidal Thalassaphorura (Collembola: Onychiuridae).

Species classification is challenging when taxa display limited morphological differences. In this paper, we combined morphology and DNA barcode data to investigate the complicated taxonomy of two Onychiurid Collembolan species. Thalassaphorura thalassophila and Thalassaphorura debilis are among the most common arthropod species in intertidal ecosystems and are often considered to be synonymous. Based on morphological and barcode analyses of fresh material collected in their type localities, we redescribed and compared the two species. However, their morphological distinctiveness was supported by a molecular divergence much smaller than previously reported at the interspecific level among Collembola. This divergence was even smaller than inter-population divergences recognized in the related edaphic species T. zschokkei, as well as those known between MOTUs within many Collembolan species. Our results may indicate a link between low genetic interspecific divergence and intertidal habitat, as the only biological peculiarity of the two species of interest compared to other Collembolan species analyzed to date is their strict intertidal life.

Two new species of the genus Thalassaphorura Bagnall, 1949 (Collembola: Onychiuridae) from south China, with an updated key to world species of the genus.

Two new onychiurid species, Thalassaphorura microspinata sp. nov. and T. guangxiensis sp. nov., are reported from the karsts of south China (Guangxi). T. microspinata sp. nov. is similar to T. grandis Sun, Chen & Deharveng, 2010 in having the same dorsal and ventral pso formula, number of pseudocelli on subcoxae 1, number of chaetae in the distal whorl of tibiotarsi and number of p-chaetae between inner posterior pso on head; but it can be recognized by the smaller body size, shorter AS, 5 chaetae on baso-lateral part of labium, distinguishable S-chaetae and absence of chaetae on Th. I sternum. T. guangxiensis sp. nov. possesses the same dorsal pso formula as Chinese species T. reducta Sun, Chen & Deharveng, 2010, T. bapen Sun, Chen & Deharveng, 2010 and T. guangdongensis Sun & Li, 2015a, but they could be separated easily by ventral pso formula, number of pseudocelli on subcoxae 1 and other combined characters. An updated key of world species of the genus Thalassaphorura is provided. The species Thalassaphorura saccardyi (Denis, 1935) is transferred to the genus Protaphorura Absolon, 1901 on examination of the type material. In addition to those listed in Sun et al. (2010), two additional species placed in Thalassaphorura by Parimuchová & Kovác 2016 are considered here as incertae sedis because of insufficient descriptions: Thalassaphorura boskovae (Lucic, Dimitrijevic & Mihajlova, 2003), and T. tamdaona (Nguyen, 1995).

An annotated checklist of the Collembolan fauna of Thailand.

The current knowledge of the Collembolan fauna of Thailand is reported here, based on the checklist of Bedos (1994) completed by data on several taxa described since this date, with an update of the taxonomic status of the species. A total of 194 species from 53 genera and 14 families are listed, that were mostly discovered and described during the last three decades. The updated checklist illustrates a strong unevenness in sampling efforts across space and habitats, and in the degree of taxonomic coverage of the different families of the group. Geographically, only the Doi Inthanon massif can be considered as relatively well known, but even there the species in several major habitats and microhabitats have not been sampled. Data are lacking or much more limited for all other regions of the country. The species richness of Thailand is undoubtedly much more than observed number.

A new species of Deutonura (Collembola: Neanuridae: Neanurinae) from Algeria, with revised diagnosis of the genus and key to western Palaearctic species.

Deutonura adriani sp. nov. is described from the region of Tizi-Ouzou (Algeria). The species is morphologically similar to D. deficiens deficiens Deharveng, 1979 from southwestern France, differing by not having De3 chaetae integrated into the dorso-external tubercle on abdominal tergites I and II. The genus Deutonura is re-diagnosed and a key to its Western Palaearctic species is provided.

The puzzling distribution of Heteromurus (Verhoeffiella) absoloni Kseneman, 1938 (Collembola: Entomobryidae: Heteromurinae) resolved: detailed redescription of the nominal species and description of a new species from Catalonia (Spain).

The species Heteromurus (Verhoeffiella) absoloni Kseneman, 1938 is redescribed in detail and characterized by its barcode, based on specimens from its type locality in Montenegro. A neotype is designated. Dorsal S-chaetotaxy is given for the first time in the subgenus Verhoeffiella. Chaeta morphology and distribution are thoroughly analyzed, in particular on antennae where 12 chaetal types are recognized. Several morphological features are newly described for the genus and for Heteromurinae. The widely disjunct distribution of the species is approached through morphological and molecular comparison of specimens from the type locality in Montenegro and from the Catalan population. We established that this last record is a new species described here as  Heteromurus (Verhoeffiella) gamae sp. nov. New combination is proposed Heteromurus (Verhoeffiella) constantinellus (Curcic & Lucic in Lucic, Curcic & Mitic 2007) comb. nov. A table of all species of the subgenus is provided. The taxonomic status of Verhoeffiella and the problems of species discriminations in the subgenus are discussed.

Phylogeny of the genus Willemia (Collembola: Hypogastruridae) and biogeography of the W. buddenbrocki-group with description of a new species from Ivory Coast (western Africa).

Willemia tondoh sp. nov. from the Ivory Coast (western Africa) is described and illustrated. The new species is the 14th in the buddenbrocki-group and is defined with two large globular sensilla placed in a cavity and covered in part by tegumental fold on antennal segment IV, 7 chaetae on antennal segment I, postantennal organ with 9 vesicles, s-chaetae subcylindrical and acuminate on abdominal terga and chaetae a1 absent on abdominal sternum IV. A phylogeny for all the 46 species of the genus Willemia is proposed. Based on the phylogentic framework, the biogeography of the buddenbrocki-group is discussed. An identification key for all 46 known species of the genus is provided.

Collembolan species diversity of calcareous canyons in the Republic of Moldova.

The study of collembolan communities from the Vîscauți canyon in Moldova revealed 63 species belonging to 41 genera and 12 families, including four species new for the fauna of the Republic of Moldova. A checklist of collembolan species identified in the five calcareous canyons sampled so far in Moldova is included, with data on habitats, life form, occurrence and comments of distribution of most remarkable species. Of the 98 recognized species of these calcareous canyons, only 38 were shared by Vîscauți and the other canyons. The richness of calcareous habitats together with the high heterogeneity in faunal composition suggests that further significant increase in the species richness of the region may be expected.

Updated list of Collembola species currently recorded from South Africa.

Understanding the abundance and richness of species is one of the most fundamental steps in effecting their conservation. Despite global recognition of the significance of the below-ground component of diversity for ecosystem functioning, the soil remains a poorly studied terrestrial ecosystem. In South Africa, knowledge is increasing for a variety of soil faunal groups, but many still remain poorly understood. We have started to address this gap in the knowledge of South African soil biodiversity by focusing on the Collembola in an integrated project that encompasses systematics, barcoding and ecological assessments. Here we provide an updated list of the Collembola species from South Africa. A total of 124 species from 61 genera and 17 families has been recorded, of which 75 are considered endemic, 24 widespread, and 25 introduced. This total number of species excludes the 36 species we consider to be dubious. From the published data, Collembola species richness is high compared to other African countries, but low compared to European countries. This is largely a consequence of poor sampling in the African region, as our discovery of many new species in South Africa demonstrates. Our analyses also show that much ongoing work will be required before a reasonably comprehensive and spatially explicit picture of South Africa's springtail fauna can be provided, which may well exceed 1000 species. Such work will be necessary to help South Africa meet its commitments to biodiversity conservation, especially in the context of the 2020 Aichi targets of the Convention on Biological Diversity.

Two new species of Willowsia from New Caledonia (Collembola: Entomobryidae).

The genus Willowsia is reported for the first time from New Caledonia. Two new species, W. neocaledonica sp. nov. and W. nigra sp. nov., are described based on material deposited at the Muséum National d'Histoire Naturelle, Paris. The new species can be distinguished from other members of the genus by coloration and characters of the dorsal chaetotaxy of the head and terga. 

New species of Sinella and Coecobrya (Collembola: Entomobryidae) from New Caledonia.

The genera Sinella and Coecobrya are reported from New Caledonia for the first time, with four new species: Sinella quadriseta sp. nov., S. claviseta sp. nov., S. copiosa sp. nov., and Coecobrya neocaledonica sp. nov. Sinella species studied here exhibit several morphological features that are not found in other non-cave species of the genus: paired teeth on inner edge of unguis closer to the base and distal unpaired tooth very tiny or absent, 2 medio-medial and 1 medio-lateral macrochaetae on Th. II, 2+2 lateral macrochaetae on Abd. III, and abundant short S-chaetae on Abd. IV. The four S-chaetae present on Abd. V are also different from the common pattern in Entomobryidae. C. neocaledonica sp. nov. does not exhibit unique features different from Coecobrya species of other areas.

Cryptic diversity in the ubiquist species Parisotoma notabilis (Collembola, Isotomidae): a long-used chimeric species?

Parisotoma notabilis is the most common species of Collembola in Europe and is currently designated as ubiquist. This species has been extensively used in numerous studies and is considered as well characterized on a morphological ground. Despite the homogeneity of its morphology, the sequencing of the barcoding fragment (5' end of COI) for several populations throughout Europe and North America revealed four distinct genetic lineages. The divergence found between these lineages was similar to the genetic distance among other species of the genus Parisotoma included in the analysis. All four lineages have been confirmed by the nuclear gene 28S. This congruence between mitochondrial and nuclear signals, as well as the geographical distribution pattern of lineages observed in Europe, supports the potential specific status of these lineages. Based on specimens from the type locality (Hamburg), the species name was successfully assigned to one of these lineages. This finding raises several problems as Parisotoma notabilis has been widely used in many ecological studies. Accumulation of new data for the different lineages detected, especially ecological information and life history traits, is needed to help resolve this situation.

The genus Ectonura Cassagnau, 1980in South Africa (Collembola, Neanuridae, Neanurinae), with a key to South African Neanurinae.

Two new species of Neanurinae (Collembola) are described from the Western Cape, South Africa: Ectonura monochaetasp. n. and Ectonura barraisp. n.Ectonura monochaetasp. n. differs from other species in the genus by its strongly reduced chaetotaxy, and the lateral shift of dorso-internal chaetae on Abd. V and their integration in the tubercles (De+DL). Ectonura barraisp. n. is similar to Ectonura natalensis (Womersley, 1934), but differs in chaetotaxic details and chaetal group arrangement. A key to the seven species of Neanurinae recorded from South Africa is given.

Two new species of the genus Leenurina Najt & Weiner, 1992 (Collembola, Neanuridae, Caputanurininae) from Primorskij Kraj (Russia).

Leenurina khualazasp. n. and Leenurina pomorskiisp. n., two new species from East Russia (Primorskij Kraj) are described. They are closely related to Leenurina jasii Najt & Weiner, 1992 from North Korea, from which they differ mainly in the number of tibiotarsal chaetae (19, 19, 18 in the new species versus 18, 18, 17 in Leenurina jasii), several chaetotaxic features and organization of dorsal granulation. The two new species may be separated by tertiary granulation (large areas fringed with large secondary granules in Leenurina pomorskii, small rounded or hexagonal areas with smaller secondary granules in Leenurina khualaza), coloration (light blue in Leenurina khualaza versus white in Leenurina pomorskii) and number of eyes (2+2 eyes in Leenurina khualaza versus 3+3 eyes in Leenurina pomorskii). An updated diagnosis of the genus Leenurina Najt & Weiner, 1992 and a key to species of Caputanurininae are given.

Cuticular compounds bring new insight in the post-glacial recolonization of a Pyrenean area: Deutonura deficiens Deharveng, 1979 complex, a case study.

BACKGROUND: In most Arthropod groups, the study of systematics and evolution rely mostly on neutral characters, in this context cuticular compounds, as non-neutral characters, represent an underexplored but potentially informative type of characters at the infraspecific level as they have been routinely proven to be involved in sexual attraction. METHODS AND FINDINGS: The collembolan species complex Deutonura deficiens was chosen as a model in order to test the utility of these characters for delineating four infraspecific entities of this group. Specimens were collected for three subspecies (D. d. deficiens, D. d. meridionalis, D. d. sylvatica) and two morphotypes (D. d. sylvatica morphoype A and B) of the complex; an additional species D. monticola was added. Cuticular compounds were extracted and separated by gas chromatography for each individual. Our results demonstrate that cuticular compounds succeeded in separating the different elements of this complex. Those data allowed also the reconstruction of the phylogenetic relationships among them. CONCLUSIONS: The discriminating power of cuticular compounds is directly related to their involvement in sexual attraction and mate recognition. These findings allowed a discussion on the potential involvement of intrinsic and paleoclimatic factors in the origin and the diversification of this complex in the Pyrenean zone. This character type brings the first advance from pattern to process concerning the origin of this species complex.