Absence Of Chaetae Research Articles

Two new species of Achaeta (Enchytraeidae, Oligochaeta) from afforested post-mining and post-fire sites in Poland

Achaeta (Enchytraeidae, Oligochaeta, Clitellata) is a genus of small, soil-dwelling annelids, peculiar by the absence of chaetae in all species. Here two new species of this genus are described from afforestation sites in southern Poland. Descriptions are based on the investigation of living and preserved material. The species are also characterized at the DNA level, using fragments of the COI and ITS genes, sequenced from the holotypes and paratypes. The worms are not longer than 4–6 mm, with about 30 to 35 segments, and with medium-large male and female reproductive organs. Achaeta florens sp. nov., discovered at a post-mining site, has four segmental pyriform glands, an oesophageal appendage restricted to segment V, a clitellum with distinct transverse rows and dorsal and ventral interruption, and spermathecae with blossom-like fields of vesicular gland cell apices around the ventrally located ectal pores. The species is without peculiar characters but the combination of characters is diagnostic. Its morphological distinction from A. nurmineni, described from the Indian subcontinent, is difficult due to the poor description of that species; A. nurmineni is therefore considered a species inquirenda. Achaeta gemmata sp. nov., discovered in high abundance at a post-fire site, is without pyriform glands but with conspicuous, gem-like lateral papillae in all preclitellar segments. The papillae are modified and enlarged epidermal gland cells that protrude into the body cavity. The species is without oesophageal appendage and has a dorsally closed clitellum and lateral spermathecal pores. It is superficially similar to Achaeta camerani, found at the same site, but can be distinguished based on sexual and non-sexual characters. A comparison of COI sequences showed 100% identity with a specimen from Sweden, erroneously identified as A. cf. brevivasa. Genetic distance between the two new species based on COI differences is 20%, distances to other species of Achaeta with publicly available COI sequences range from 16% to 26%.

Paravietnura gen. n., a new intriguing genus of Neanurini from the Caucasus (Collembola, Neanuridae, Neanurinae).

Paravietnura gen. n. is described and established for two new species of Neanurini from the Caucasus. The new genus is characterized by an unusual combination of features: the fusion of all lateral tubercles on the head into a single mass, the strong reduction of chaetae on the head, the fusion of cephalic tubercles Af and Oc into a transverse band, the absence of labial chaetae f, the presence of microchaetae on furca rudimentary, and the penultimate abdominal tergum with two tubercles separated along the midline. Paravietnura gen. n. strongly resembles Vietnura Deharveng & Bedos, 2000, a monotypic genus up to date known only from Vietnam. The main characteristics of Paravietnura notabilis sp. n. include an ogival labrum, the absence of chaetae A on the head, relatively thick and widely sheathed long macrochaetae, and minute microchaetae without chaetopores on furca rudimentary. Paravietnura insolita sp. n. differs from the previous species in chaetotaxic details, the size of furcal microchaetae, and the shape of the labrum. Short comments on the generic diversity of the tribe in the Western Palaearctic are also provided.

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 & Kováč 2016 are considered here as incertae sedis because of insufficient descriptions: Thalassaphorura boskovae (Lučić, Dimitrijević & Mihajlova, 2003), and T. tamdaona (Nguyen, 1995).

Remarkable diversity of the genus Endonura Cassagnau, 1979 (Collembola: Neanuridae: Neanurinae) in the Caucasus.

Endonura alticola (Stach, 1951) comb. nov. is redescribed based on the type material and seven new species of the genus Endonura are described from the various parts of the Caucasus. E. paracantabrica sp. nov. can be recognized by the number of chaetae (L+So) on head and a fusion of tubercles Di and De on the first thoracic segment. Specific traits of E. aibgai sp. nov. include small body size, low number of chaetae (L+So) on head, nonogival labrum, dentate claws, and long tibiotarsal chaetae B4 and B5. E. diminutichaeta sp. nov. is characterized by an unusually short chaeta Di1on abdomen IV. E. dobrolyubovae sp. nov. can be distinguished from its congeners by notably long chaeta Ocp on head and the presence of male ventral organ. The absence of chaetae E and O on head, ogival labrum, cryptopygy and dentate claws are typical of E. cryptopyga sp. nov. E. ossetica sp. nov. is most easily recognized by an unusual shape of tubercle Af on head connected with chaetae D and E. Main characteristics of E. kremenitsai sp. nov. include the presence of chaeta E and five chaetae Dl on head. A key to all known species of the genus including the above outlined taxa is given. General remarks on distribution and possible historical biogeography of the genus are also provided.

New species of Ampharetidae (Annelida: Polychaeta) from the Arctic Loki Castle vent field

Ampharetid polychaetes adapted to live in chemosynthetic environments are well known from the deep Pacific and Atlantic Oceans, but to date no such species have been reported from the Arctic Ocean. Here, we describe two new species, Paramytha schanderi gen. et sp. nov. and Pavelius smileyi sp. nov., from the Arctic Loki’s Castle vent field on the Knipovich Ridge north–east of the island of Jan Mayen. The new species are both tube-builders, and are found in a sedimentary area at the NE flank of the vent field, characterized by low-temperature venting and barite chimneys. The new genus, Paramytha, is characterized by a prostomium without lobes or glandular ridges, smooth buccal tentacles, four pairs of cirriform branchiae arranged as 2+1+1 without median gap dorsally on segments II–IV, absence of chaetae (paleae) on segment II, and absence of modified segments. P. smileyi sp. nov. is placed in the previously monotypic genus Pavelius, primarily based on the presence of a rounded prostomium without lobes and four pairs of branchiae arranged in a single transverse row without median gap dorsally on segment III. Pavelius smileyi sp. nov. differs from the type species, Pavelius uschakovi, in the number of thoracic and abdominal chaetigers, and the absence of chaetae (paleae) on segment II. The phylogenetic position of the two new species from Loki’s Castle is further explored by use of molecular data. New sequences of mitochondrial (16S rDNA and cytochrome c oxidase subunit 1, COI) and nuclear (18S rDNA) markers have been produced for both species from Loki’s Castle, as well as for specimens identified as Paramytha sp. from Setùbal Canyon off Portugal, and for the following species: Pavelius uschakovi, Grassleia cf. hydrothermalis, Sosane wireni, Amphicteis ninonae and Samythella neglecta. Results from phylogenetic analysis, including 22 species and 12 genera of Ampharetidae, recovered Paramytha gen. nov. as monophyletic with maximum support, and a close relationship between the genera Pavelius and Grassleia which together form a well supported monophyletic clade.

New species of Monodontocerus (Collembola: Tomoceridae) from southern China with diagnostic notes on the genus and introduction of new taxonomic characters.

Three new species of Monodontocerus are described from caves in southern China: M. absens sp. nov. is characterized by its cephalic chaetotaxy and the absence of chaetae from the tenaculum; M. mulunensis sp. nov. is characterized by a combination of characters including chaetotaxy, foot complex and furca; M. trigrandis sp. nov. is different from other species in the formula of dental spines and the reduction of the ungual teeth. A key to the species of Monodontocerus is provided. Potential diagnostic characters for this genus are proposed. Troglomorphy and interspecific variability are discussed. Pseudopores and the dorsal disto-lateral chaeta on the manubrium are introduced as new taxonomic characters for Tomocerinae.

Review of Chinese littoral Thalassaphorura (Collembola: Onychiuridae), with the description of two new species

The present paper is the third contribution to the knowledge of littoral Collembola of China. Species of the genus Thalassaphorura occurring in sandy and shingly beaches in China are reviewed. Descriptions of two new species, Thalassaphorura brevisetosa sp. nov. and Thalassaphorura hainanica sp. nov. are provided. Thalassaphorura duplopunctata and Thalassaphorura lifouensis are recorded for the first time from China, and T. duplopunctata is re-described mainly based on Chinese specimens. Thalassaphorura brevisetosa sp. nov. is characterized by having strongly reduced unguiculus and very short body chaetae. Thalassaphorura hainanica sp. nov. resembles Thalassaphorura pomorskii from which it differs by 2 + 2 pso on Abd. IV, absence of chaetae on Th. I sternum and four chaetae on subcoxa 1 of leg I, among other characters.http://www.zoobank.org/urn:lsid:zoobank.org:pub:B8AC3DB3-DF12-47E2-ACEE-969D72C594C8