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Symphylella minutasp. nov. and Symphylella communasp. nov. from China are described and illustrated. Symphylella minutasp. nov. is characterized by the delicate and minute body, a well-developed and thin central rod with a vestige of a transverse suture in the middle, eight setae on the first tergite, pointed processes on the tergites, and short cerci with sparse setae. Symphylella communasp. nov. is characterized by the chaetotaxy of the first tergite with 4+4 setae, processes of the tergites somewhat longer or the same length with broad, most of lateromaginal setae long, anterolateral setae of tergites 2–4, 6, 7, 9, and 10 distinctly longer than other lateromarginal setae, approximately as long as the process of the same tergite, and cerci with numerous subequal and slightly curved setae. In addition, the chaetotaxic variation on the tergites, the distribution, the habitat, and the feeding habit of the genus Symphylella are discussed.

From a biodiversity survey of a subterranean habitat near Sinan County, Guizhou Province, southwestern China, a new atyid shrimp of the genus Caridina H. Milne Edwards, 1837, C. sinanensissp. nov. was discovered. The new species can be separated from other congeners based on a combination of characters including depigmentation in body and reduction of eyes, small pigment spot at the centre of the cornea, the shape of rostrum and the endopod of the 1st male pleopod, and the relatively longer appendix interna on the appendix masculina of the 2nd pleopod. Mitochondrial COI and 16S rRNA gene sequences also support the establishment of the new species. Information on the habitat, and the levels of threat are discussed to guide the conservation of C. sinanensissp. nov.

The genus Notomastus is frequently encountered in Chinese waters. However, its species richness is poorly understood. In this study, a Notomastus species obtained from Xiamen Bay, southern China, was described and illustrated as a new species (N. sunaesp. nov.), based on morphological and molecular analyses. The new species is characterized by having uniramous chaetiger 1, the presence of palpode and eyespots on prostomium, chaetiger 11 with notopodial capillaries and neuropodial hooded hooks, and notopodial lobes with simple epithelial extensions on far posterior abdomen. With additional specimens collected from several localities along the southern coasts of China, the morphology and geographical distribution of the new species are discussed. A key is also provided for Notomastus species with neuropodial hooks in thoracic chaetiger 11.

We describe a new species of polyclad flatworm, Enchiridium daidaisp. nov., from the rocky subtidal zone in the East China Sea along the coasts of the Kyushu and Okinawa Islands, Japan. Enchiridium daidaisp. nov. is characterized by i) the entire periphery of the dorsal surface narrowly fringed with orange, ii) a marginal-eyespot band extending to the position of the mouth (about anterior one-eighth of body), and iii) two prostatic vesicles covered by a common muscle sheath, which is penetrated by the ejaculatory duct. We performed a molecular phylogenetic analysis based on 945-bp 28S rDNA sequences of 16 species of Prosthiostomidae currently available in public databases in addition to those of E. daidaisp. nov. and Prosthiostomum torquatumTsuyuki et al., 2019. In the resulting tree, our new species was nested in a clade composed of Enchiridium species. The tree topology was in favor of a taxonomic view that Enchiridium should be defined by having i) a common muscle sheath that encloses two prostatic vesicles and ii) marginal eyespots that may or may not surround the periphery of the dorsal surface.

A new species of temnocephalan is described from the branchial chambers ofValdivia serratain Colombia asTemnocephala ivandarioisp. nov.The most distinctive characters of the new species are in the cirrus and the epidermal ‘excretory’ syncytial plates. In the present study, the terminology to describe the cirrus of species ofTemnocephalais updated. Comparison between the shape of the cirrus of the temnocephalans associated with trichodactylid crabs is also provided.

We identified Basidiobolus fungi on geophilomorphan centipedes (Chilopoda) from caves of Southeast Brazil. Twelve specimens of centipedes of the family Geophilidae were examined, and two of them carried the secondary capilliconidia of Basidiobolus on their exoskeleton. The fungus uses the surface of the exoskeleton as a support for the asexual reproductive structure. In this manner, the host is used for the purpose of dispersing its spores. This study expands current knowledge of the diversity of arthropods used as host for the fungus, and in particular for Basidiobolus, living in cave habitats.

Three undescribed species of Heteromastus Eisig, 1887 were collected from intertidal to sublittoral habitats in western and southern waters of Korea. Heteromastus namhaensis sp. nov. is distinguishable from other congeners by the presence of hemispheric notopodial lobes in the posterior abdomen. Heteromastus gusipoensis sp. nov. closely resembles H. tohbaiensis Yabe & Mawatari, 1998 in the absence of posteriorly extended abdominal notopodial lobes, but differs in the absence of eyespots on the prostomium and distinct node on the shaft of thoracic hooks in H. gusipoensis. Heteromastus koreanus sp. nov. is similar to H. filiformis sensu Hutchings & Rainer, 1982 in the shape of abdominal notopodia, but clearly differs in dentition of the abdominal hooks and methylene green staining pattern (MGSP). DNA sequences (mtCOI and histone H3) of these new Korean species were compared with all sequences of Heteromastus species available in the public database. Molecular results showed distinct genetic differences among these three new Korean species at species level. Comparison of mtCOI gene revealed significant genetic difference between H. filiformis and these Korean species. A comprehensive comparison between three Heteromastus species of present study and their closely related congeners is conducted based on morphological and genetic results.

This nomenclator provides bibliographic details on all names in the family-, genus-, and species-group of the the family Paludomidae. All nomenclaturally available names are discussed including junior homonyms and objective junior synonyms as well as unavailable names such as nomina nuda, infrasubspecific names and, to some extent, also incorrect subsequent spellings. In the family-group a total of 28 names are included in the nomenclator, of which 21 are available and seven unavailable names. Of the available names in the family-group, six are invalid for nomenclatural reasons. In the genus-group a total of 57 names are included in the catalogue. Of the available names in the genus-group, 11 are invalid for nomenclatural reasons. In the species-group a total of 499 names are included, of which 463 are available, but 21 are invalid for nomenclatural reasons. All names are given in their original combination and spelling (mandatory changes are discussed and corrected spellings are provided), along with the reference to the original publication. For each family- and genus-group name, the original classification and the type genus or type species, respectively, are given. For species-group taxa the type locality and type horizon (for fossil taxa) are provided, usually as given in the original publication. A new name,Cleopatraadaminom. nov., is proposed for the fossilCleopatracylindrica(Adam, 1957), which is a homonym ofCleopatracridlandicylindricaMandahl-Barth, 1954, and a lectotype forCleopatradubiaAdam, 1959 is designated. A new replacement nameLeloupiellanom. nov. is proposed forStormsiaLeloup, 1953 which is a homonym ofStormsiaBourguignat, 1891.

Two new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Hainan Island of China are described on the basis of morphological, karyological and molecular data. Dugesia semiglobosa Chen & Dong, sp. nov. is mainly characterized by a hemispherical, asymmetrical penis papilla with ventrally displaced ejaculatory duct opening terminally at tip of penis papilla; vasa deferentia separately opening into mid-dorsal portion of intrabulbar seminal vesicle; two diaphragms in the ejaculatory duct; copulatory bursa formed by expansion of bursal canal, lined with complex stratified epithelium, which projects through opening in bursa towards intestine, without having open communication with the gut; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24), with metacentric chromosomes. Dugesia majuscula Chen & Dong, sp. nov. is mainly characterized by oviducts opening asymmetrically into female reproductive system; hyperplasic ovaries; expanded posterior section of bursal canal; vasa deferentia separately opening into mid-dorsal portion of seminal vesicle; asymmetrical penis papilla due to ventral course of ejaculatory duct, which has subterminal and dorsal opening at tip papilla; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24); chromosomes metacentric. Apart from their anatomy, separate species status of the two new species is supported also by their genetic distances and by their positions in the phylogenetic tree. The sexualization process may have been induced by the lower temperatures, in comparison with their natural habitat, under which the worms were cultured in the laboratory.

Ornamentula Kisielewski, 1991 is a monospecific genus in Order Chaetonotida. The sole species, O. paraensis Kisielewsk, 1991, is a semiplanktonic gastrotrich found in a single pond in the Amazon region of Brazil. Herein we describe a new species of the genus Ornamentula, collected in a small urban lagoon in the Atlantic Forest of southeast Brazil. Ornamentula miyazakiisp. nov. resembles O. paraensis, but it shows differences in the ornamented trunk scales and spinal spines distribution, sufficient to proposte it as it’s a new species.

Living representatives of the Neotropical genus Choeradoplana Graff, 1896 ( Geoplaninae , Tricladida , Platyhelminthes ) are easily recognized by the typical shape of the head which is laterally expanded, rolled-up, and ventrally provided with two glandular cushions. In this study, the morphology and phylogeny (cytochrome C oxidase subunit I gene) of several species of land planarians are taxonomically investigated. Four of the six species studied are new to science, namely: Ch. eudoxiae Silva & Carbayo, sp. nov., Ch. claudioi Lago-Barcia & Carbayo, sp. nov., Ch. onae Lago-Barcia & Carbayo, sp. nov., and Ch. riutortae Lago-Barcia & Carbayo, sp. nov. The species Choeradoplana albonigra and Ch. eudoxiae deviate from the usual body shape pattern in that the head does not present lateral expansions nor glandular cushions, becoming indistinguishable from its sister genus Cephaloflexa . Pseudogeoplana tristriata (Schultze & Muller, 1857) is also redescribed from a newly collected specimen and was discovered to be a member of Choeradoplana . Graff (1899) also studied another specimen that was considered to be conspecific with P. tristriata ; however, in this new it is concluded that it is not conspecific but rather a new species. The name Pseudogeoplana aevipandemiae Lago-Barcia & Carbayo, sp. nov. is suggested for Graff’s specimen.

The cerithioidSupplanaxis nucleus(Bruguière, 1789) is widespread in the Caribbean, where it lives in often dense aggregates on hard surfaces in the middle-high intertidal. Molecular evidence shows that it comprises two species that are in fact morphologically diagnosable. We fix the nomenclature ofSupplanaxis nucleusby designating a sequenced neotype from Bruguière’s historical locality of Barbados, and identify the second, cryptic species asS. nancyae(Petuch, 2013). The two live syntopically across the Caribbean and form a closely related species group with the PanamicS. planicostatus(G.B. Sowerby I, 1825).Planaxis nucleolaMörch, 1876, described from St Croix, in the Virgin Islands, never again recorded in the literature but listed as a synonym ofS. nucleusin taxonomic authority lists, is recognized as a valid species ofHineaGray, 1847.ProplanaxisThiele, 1929 andSupplanaxisThiele, 1929, are synonyms and the latter is given precedence over the former.

Two new species of Aricidea Webster, 1879 (Paraonidae), Aricidea (Acmira) anusakdiisp. nov. and Aricidea (Aricidea) thammapinanaesp. nov. were collected from 10–26.5 m depth, in soft bottoms with mud mixed with sand and shells at Songkhla Sea, the Gulf of Thailand between 2011–2018. Aricidea (Acmira) anusakdiisp. nov. is clearly distinguished from other species of the subgenus Acmira by having a rounded bilobed prostomium divided by a slight notch on the anterior margin; red pigments on the subdistal to the tip of each branchia (new character); two prebranchial chaetigers; 48–68 pairs of branchiae; and modified neurochaetae as strong curved spines with blunt shafts surrounded by pubescence from chaetigers 19–44. On the other hand, Aricidea (Aricidea) thammapinanaesp. nov. can be separated from other members of the subgenus Aricidea by the presence of a biarticulated median antenna; distinctive notopodial lobes as broad triangular with short distal protuberances on chaetiger 3, 4–8 pairs of branchiae; and modified neurochaetae as bidentate neurochaetae with a long pubescent subterminal arista on the concave side. All data have been archived and are freely available from the Dryad Digital Repository (https://doi.org/10.5061/dryad.hqbzkh1cn).

Research in recent years have provided rapid advances in biogeographic and taxonomic documentation of sea slugs around the world. However, efforts are lacking in surveying most coastlines and habitats in South-East Asia. Recent studies from the Gulf of Thailand have indicated that a wealth of unexplored sea slug diversity and ecology may be gained from an investigation of soft sediment habitats beyond the reef slopes. Additionally, the waters of Koh Tao have been found to host regionally high levels of sea slug diversity with several species awaiting taxonomic clarification. In this work the initial findings of an expanded survey effort from the waters around Koh Tao are provided, with the identity of two soft sediment-associated sacoglossan species in the family Plakobranchidae being investigated. By integrating morphological and molecular analyses, the species Plakobranchus noctisstellatus sp. nov. and Elysia aowthai sp. nov. are described and species complexes surrounding Plakobranchus ocellatus van Hasselt, 1824 and Elysia japonica Eliot, 1913 are discussed. The topics of morphological variability and the cryptic species problem are also discussed.

The genusScolopendrellopsisBagnall, 1913 is recorded from China for the first time andScolopendrellopsisglabrussp. n.is described and illustrated. The new species is characterized by the short central rod on head, third tergite complete, four kinds of sensory organs present on antenna, and the cerci rather short and covered with a low number of straight setae.

Tintinnids are an essential link between nano- and macro- planktons in the food webs of the marine environment. It is also known that tintinnids are one of themajor components of marine planktonic ciliates and has a cosmopolitan character. In the Philippine archipelago, which is recognized as a center of marine biodiversity, tintinnids checklist has not been done or published. Therefore, a checklist is presented in this study based on a compilation of previous tintinnids studies conducted at the Philippines waters. As a result of the studies done since 1941 up to present, a total of 114 taxa belonging to 14 families and 37 genera were listed. The Philippines coastal waters record a total of 50 species while the open seas document 72 species to date.

A new genus, Limatium gen. n., and two new species, L.pagodula sp. n. and L.aureum sp. n. are described, found on outer slopes of barrier reefs and fringing reefs in the South Pacific. They are rare for cerithiids, which typically occur in large populations. The two new species are represented by 108 specimens sampled over a period of 30 years, only 16 of which were collected alive. Three subadults from the Philippines and Vanuatu likely represent a third species. In addition to their rarity, Limatium species are atypical for cerithiids in their smooth, polished, honey to golden brown shells with distinctive white fascioles extending suture to suture. The radula presents a unique morphology that does not readily suggest an affinity to any of the cerithiid subfamilies. Two live-collected specimens, one of each species and designated as holotypes, were preserved in 95% ethanol and sequenced. Bayesian analysis of partial COI and 16S rDNA sequences demonstrates a placement in the Bittiinae, further extending our morphological concept of the subfamily.

Notomastuskoreanussp. n., collected from the sublittoral muddy bottom of Korean waters, is described as a new species. The Korean new species closely resembles N.torquatus Hutchings & Rainer, 1979 in the chaetal arrangement and the details of abdominal segments, but differs in the position of genital pores and the absence of eyes. DNA sequences (mtCOI, 16S rRNA, and histone H3) of the new species were compared with all the available sequences of Notomastus species in the GenBank database. Three genes showed significant genetic differences between the new species and its congeners (COI: 51.2%, 16S: 38.1–47.3%, H3: 3.7–9.3%). This study also includes a comprehensive comparison of the new Korean Notomastus species with its most closely similar species, based on the morphological and genetic results.

Two mealybug species (Hemiptera: Coccomorpha: Pseudococcidae), Pelionella osakaensis sp. n. and P. manifecta (Borchsenius, 1949), are described and illustrated based on adult female specimens collected in Japan, on the Japanese mugwort Artemisia indica Willd. var. maximowiczii (Nakai) H. Hara (Asteraceae). These are the first records of the occurrence of Pelionella species in East Asia. The new species is similar to P. grassiana (Goux, 1989) and P. proeminens (Goux, 1990), but differs in lacking multilocular pores with double loculi rings on the venter and in possessing dorsal cerarii and a circulus. The Japanese population of P. manifecta is morphologically slightly different from the Azerbaijani and French populations in lacking large-type oral-collar tubular ducts associated with clusters formed by multilocular pores and oral-collar ducts on ventral abdominal segments III and IV. A modified key to species of the genus Pelionella Kaydan, 2015, is provided.

The polychaete fauna from the mangroves of the Amazon Coast in Maranhão state, Brazil, is reported in this study. Fourteen species are listed, namely Alittasuccinea (Leuckart, 1847); Arabella (Arabella) iricolor Montagu, 1804; Capitellacapitata (Fabricius, 1780) complex; Exogone (Exogone) breviantennata Hartmann-Schröder, 1959; Heteromastusfiliformis (Claparède, 1864); Isoldapulchella Müller, 1858; Mediomastuscaliforniensis Hartman, 1944; Namalycastisfauveli Nageswara Rao, 1981; Namalycastisgeayi (Gravier, 1901); Namalycastissenegalensis (Saint-Joseph, 1901); Nephtyssimoni Perkins, 1980; Paraonisamazonica sp. n.; Sigambrabassi (Hartman, 1945); and Sigambragrubii Müller, 1858. Among them, Namalycastisfauveli and Namalycastisgeayi are recorded for the first time in Brazil. Paraonisamazonica sp. n. is a new species for science, characterized by a rounded prostomium, 4–8 pairs of foliaceous branchiae, absent eyes, and two types of modified neurochaetae, acicular and hook-shaped.

Two new species of the genus Mesopsyllus Por, 1960 (Canthocamptidae) are described from the Bohai Sea, eastern China. Mesopsyllus dimorphus sp. n. and M. spiniferus sp. n. differ from their congeners by the presence of two instead of three outer spines on P2–P3 exp-3. They can be differentiated from each other by (1) number of inner setae on P3–P4 enp-2; (2) anterior margin of antennulary segment 7 of male; (3) ornamentation of male abdomen; (4) sexual dimorphism on P2 endopod and P3–P4 exp-3; and (5) differences in length of setae on male P5. Some observations in the original description of M. atargatis Por, 1960 are reinterpreted and the type material of M. secundus (Wells, 1965) is re-examined. Comparison between the type species of Vibriopsyllus Kornev & Chertoprud, 2008 and the four known species of Mesopsyllus shows the former as a junior subjective synonym of the latter. Consequently, Vibriopsyllus curviseta Kornev & Chertoprud, 2008 is formally transferred to Mesopsyllus as M. curvisetus (Kornev & Chertoprud, 2008), comb. n. A key to species and an updated generic diagnosis of Mesopsyllus are presented. The taxonomic status of the genus Carolinicola Huys & Thistle, 1989 is re-evaluated. The characters of its type species, C. trisetosa (Coull, 1973), indicate that the latter (and – by inference – the genus Carolinicola) should remain in the Danielsseniinae. Carolinicola galapagoensis Mielke, 1997 is fixed as the type species of a new genus Sympodella gen. n. and placed in the Hemimesochrinae (Canthocamptidae) as the putative sistertaxon of Pusillargillus Huys & Thistle, 1989. The relationships and potential synonymy of the genera Pyrocletodes Coull, 1973, Perucamptus Huys & Thistle, 1989 and Isthmiocaris George & Schminke, 2003 are briefly discussed.

A new species of coral associated barnacle (Balanomorpha: Pyrgomatidae) sharing morphological features of Darwiniella (Anderson, 1992) and Galkinius Perreault, 2014 is described. It has a fused shell and opercular plates, characteristic of Darwiniella. However, the morphology of the tergum and somatic body are closer to Galkinius. Sequence divergence of mitochondrial DNA 12S rDNA and COI reveals this new species clusters with the Galkinius clade. Therefore this new form is assigned to the genus Galkinius, as G. maculosus sp. n. Concomitantly the diagnosis of Galkinius is emended to include species with fused or four- plated shells and fused opercular plates. The new species is distinct from all Galkinius species in having a fused shell. It inhabits the corals Lobophyllia spp. and is distributed from the Dongsha Atoll in the South China Sea, Orchid Island of Taiwan in the Pacific Ocean, to Madang in Papua New Guinea waters.

Two new species of Drawida Michaelsen, 1900, namely Drawida polydiverticulata Narayanan & Julka, sp. n. and Drawida thomasi Narayanan & Julka, sp. n., are described from material collected from the Indian state of Kerala, which lies in the Western Ghats biodiversity hotspot. Drawida elegans Rao, 1921, Drawida kanarensis Stephenson, 1917, Drawida modesta Rao, 1921, Drawida somavarpatana Rao, 1921, and Drawida thurstoni Gates, 1945 are recorded for the first time from the state.

We describe two new species of pebblesnails (Lithoglyphidae: Fluminicola) from southwest Oregon based on morphologic and mitochondrial DNA (COI, cytB) evidence. Fluminicola umpquaensis sp. n., which had been traditionally identified as F. virens prior to the recent restriction of the latter to the lower Columbia River drainage, lives in lotic habitats in the Umpqua River basin. This species is readily distinguished from closely related F. gustafsoni and F. virens by shell and anatomical characters, and by its mtDNA sequences (divergence >3.6% for both genes). Fluminicola fresti sp. n. ranges among lotic habitats in the North Umpqua River basin, and in the upper Rogue River drainage north of Little Butte Creek. This species differs from other congeners by >9.1% for both genes and is distinguished from closely similar and geographically proximal F. multifarius by several anatomical characters. Additionally, new records are provided for F. multifarius from the upper Rogue River basin south of Little Butte Creek, which extend the geographic range of this species about 80 km northward from the Sacramento River headwater region. This continues a recent series of taxonomic papers on the poorly known and little studied pebblesnail fauna of the vast Pacific watershed from northern California to southern British Columbia.

Hirudinaria manillensis (Lesson, 1842), commonly known as the buffalo leech, shows a polymorphism of two ventral colorations. The green color morph has a plain green ventral surface and the red color morph has a brick-red ventral surface with two black submarginal stripes. Based on molecular and morphological evidence in the present study, these two color morphs were revealed as two different species. The red color morph fits well with the description of H. manillensis, while the green color morph showed some distinctions, and therefore is described herein as Hirudinaria thailandica Jeratthitikul & Panha, sp. nov. The new species can be distinguished from its congeners by the dark greenish or dark olive ventral surface and a round atrium with ventral insertion of ejaculatory ducts in the male reproductive organ. A phylogenetic tree based on concatenated data of COI and 28S genes supported the new species and further indicated it as a sister species to H. bpling Phillips, 2012.

Freshwater hairworms (class Gordiida) are members of the phylum Nematomorpha that use terrestrial arthropods as definitive hosts but reside as free-living adult worms in rivers, lakes, or streams. The genus Gordius consists of 90 described species, of which three species were described from freshwater habitats in North America. In this paper we describe a new species of Gordius from terrestrial habitats in Oklahoma, Texas, and Louisiana, United States. Oddly, each year hundreds of adult free-living worms appear after bouts of heavy rain on streets, sidewalks, and lawns during the winter season, when terrestrial arthropod hosts are not active. The new species is described based on morphological characters of adults and non-adult stages including the egg strings, eggs, larvae, and cysts. Adult males have a unique row of bristles on the ventral inner side of each tail lobe and a circular pattern of bristles on the terminal end of each lobe, which distinguishes them from all other described North American species of Gordius. The egg string, larval, and cyst morphology of this new species conform to previous descriptions of non-adult hairworm stages for the genus Gordius. However, the eggs of this new species of hairworm are unique, as they contain an outer shell separated by distinct space from a thick inner membrane. The consistent occurrence of this gordiid in terrestrial habitats, along with its distinct egg morphology, suggests that this new species of hairworm has a terrestrial life cycle.

In 2016, the type-material of ten of the 15 Brazilian land planarians (Platyhelminthes, Tricladida, Geoplanidae) described by Schirch (1929) was discovered deposited in the Museu Nacional do Rio de Janeiro (MNRJ). Schirch only described the external morphology of these species, all originally placed in the genus Geoplana. By the 1930s and 1950s Geoplana itatiayana, G. plana, and G. rezendei underwent taxonomic revision based on the study of non-type specimens. The remaining 12 species also underwent a taxonomic revision but only based on the literature. Current names of these species are Geoplana goettei, Pseudogeoplana arpi, Ps. blaseri, Ps. bonita, Ps. bresslaui, Ps. cardosi, Ps. doederleini, Ps. lumbricoides, Ps. obscura, Ps. riedeli, Ps. theresopolitana, and Ps. wetzeli. The species Geoplana maximiliani sensu Schirch (1929) was renamed as Ps. schirchi Ogren & Kawakatsu, 1990. The present study reports a taxonomic revision of seven of Schirch’s species using type material, namely Obama itatiayana, Pasipha plana, Pseudogeoplana arpi, Ps. bresslaui, Ps. doederleini, Ps. schirchi and Ps. wetzeli. Additional specimens of some of these species were also examined. Morphological data from histological preparations and from virtual sections were obtained through a non-destructive technique of X-ray computed microtomography (µCT). This approach resulted in the preservation of the entire body of at least one type-specimen of each species, and the holotype of Ps. bresslaui. Conspecificity of O. itatiayana and P. plana was confirmed, as previously reported in the literature. It is also proposed that Ps. bresslaui belongs to the genus Paraba, while the other species should remain in Pseudogeoplana, since type-specimens are either immature, poorly preserved or simply lost.

The Symphyla of Tibet are studied for the first time. Symphylellamacroporasp. n. and Symphylellazhongisp. n. from southeastern Tibet are described and illustrated. Symphylellamacroporasp. n. is characterized by large, elongated oval openings of the Tömösváry organ with its inner margins covered by minute irregular teeth, rudimentary spined sensory organs present on the dorsal side of most antennal segments, and cerci with numerous long and slightly curved setae. Symphylellazhongisp. n. is characterized by a globular Tömösváry organ with a small and roundish opening, mushroom-shaped sensory organs present on apical antennal segments, and by having tergal processes longer than their basal width with ovoid swollen ends. The newly described species are compared to the morphologically closest congeners: S.javanensis, S.asiatica, S.multisetosa, and S.simplex. A key for 43 species of the genus is also provided.

The first record of the amphioxusBranchiostoma californienseon seagrass patches ofHalodule wrightiiin the Gulf of California is reported. Sixty individuals (19 males, 18 females, and 23 undifferentiated) were collected in May 2017 at Bahía Balandra, Gulf of California, from subtidal seagrass patches at a depth of 0.5 m at low tide. The length and weight ranged from 15.88–28.44 mm and from 0.01–0.11 g for females and 11.7–27.9 mm and 0.01–0.09 g for males, respectively. The minimum size of sexually mature individuals was 11.70 mm for males and 15.88 mm for females; 62% of the specimens were sexually mature. Analysis of the total length-weight relationship suggested an allometric growth pattern among females, males and undifferentiated individuals, whereas an analysis of the entire sample suggested an isometric growth pattern. Typical and additional morphological characters were used to identify the amphioxi. High morphological variability between individuals was found, suggesting the presence of several morphotypes.Branchiostoma californiensehad been previously reported as exclusively associated with bare sandy areas, but our study shows that this species can also be found in seagrass patches, using them as breeding and feeding grounds. Thus, seagrass patches are evidenced as suitable habitats for amphioxus.

Outbreaks of ribbon worms observed in 2013, 2015, and 2017–2019 in the Han River Estuary, South Korea, have caused damage to local glass-eel fisheries. The Han River ribbon worms have been identified asYininemertespratensis(Sun & Lu, 1998) based on not only morphological characteristics compared with the holotype and paratype specimens, but also DNA sequence comparison with topotypes freshly collected near the Yangtze River mouth, China. Using sequences of six gene markers (18S rRNA, 28S rRNA, histone H3, histone H4, 16S rRNA, and COI), the phylogenetic position ofY.pratensiswas inferred among other heteronemerteans based on their sequences obtained from public databases. This analysis firmly placedY.pratensisas a close relative toApatronemertesalbimaculosaWilfert & Gibson, 1974, which has been reported from aquarium tanks containing tropical freshwater plants in various parts of the world as well as a wild environment in Panama.

Traumatophoratriscalpta(Martens, 1875) is reported for the first time from the Tianmushan Mountains, Zhejiang Province, and its morpho-anatomy is described based on this new material. The genusTraumatophorais redefined on the basis of both shell and genital anatomy of its type species. The presence of the dart apparatus suggests this genus belongs to the subfamily Bradybaeninae rather than to the Camaeninae. This genus is distinguished from all other Chinese bradybaenine genera by the combination of the following key morphological characteristics: embryonic shell smooth, palatal teeth present, dart sac tiny with rounded proximal accessory sac that opens into a dart sac chamber, mucous glands well developed, entering an accessory sac through a papilla, epiphallic papilla absent, flagellum present. A comparison is also presented of Chinese bradybaenine genera with known terminal genitalia.

Zospeumpercostulatumsp. n. from Cueva de La Herrería (Llanes, Asturias) is described. It is characterized by a relatively large shell (1.4–1.8 mm height), conical, with ovate aperture, continuous peristome and thickened parietal callus; shell costulate except two first whorls; without any sort of inner formations. It is the first clearly costulate Iberian species, filling a morphological gap in the Iberian clade, and the largest species from the Cantabrian region, being the first species described from Asturias.

The oegopsid squids Abraliopsis and Pterygioteuthis are abundant and diverse genera with taxonomic and distributional problems. Identification and distribution of species in the Mexican Pacific has been somewhat controversial. Here are provided a large series of new records for Abraliopsis affinis, Abraliopsis falco, Pterygioteuthis gemmata, Pterygioteuthis giardi and Pterygioteuthis hoylei from the Gulf of California and off the SW coast of Mexico. All five species were collected in the central or the southern Gulf of California, or in both. Abraliopsis affinis was found in seven samples with a total of 48 specimens, from 21°59' to 24°53'12"N. Abraliopsis falco was much less represented in the samples (14 specimens) but it was found in 10 localities, four of which correspond to the central-southern Gulf of California (north to 27°44'53"N) and six to SW Mexico (south to 16°49'18"N). In the case of Pterygioteuthis gemmata, only two records (three specimens) were obtained, both in the SW Gulf of California, while Pterygioteuthis giardi (nine specimens) records were all from the central Gulf of California (27°44'53” to 25°39'59"N). In the case of Pterygioteuthis hoylei (nine specimens), material was obtained in six localities, also in a restricted latitudinal range (24°23'48” to 25°56'56"N).

Interactions between algae and herbivores can be affected by various factors, such as seasonality and habitat structure. Among herbivores inhabiting marine systems, species of the order Patellogastropoda are considered key organisms in many rocky coasts of the world. Nacella species are one of the most dominant macro-herbivores on the rocky shores of the sub-Antarctic ecoregion of Magellan. However, the importance of its key role must be associated with its trophic ecology. The objective of this work was to evaluate spatial and temporal variabilities in the dietary composition of two intertidal Nacella species, considering grazing on macro- (macroalgae) and microscopic (periphyton) food. The composition of periphyton and the availability of macroalgae in the winter and summer seasons were examined at two localities of the Magellanic province, alongside the gut contents of N. magellanica and N. deaurata. The dietary composition differed between the two Nacella species, as well as between seasons and locations. The differences observed in the diet of the two species of Nacella may be mainly due to their respective distributions in the intertidal zone. Both species presented a generalist strategy of grazing, which is relationed to the seasonality of micro- and macroalgae availability and to the variability of the assemblages between the localities. This research was the first to perform a detailed study of the diet of intertidal Nacella species.

The study falls within the framework of a wider research programme aimed at investigating the gastrotrich diversity of the Tropical North-Western Atlantic (TNWA). A new macrodasyidan gastrotrich is described from fine-medium sand collected at Duncans Bay, Jamaica. The description is based on observations carried out on living specimens using differential interference contrast microscopy. Paraturbanella xaymacana sp. n., the third gastrotrich taxon reported from Jamaica, is a mid-sized species, up to 564 μm long, with a feeble peribuccal swelling. The most obvious autapomorphic traits pertain to the testes and the male pore, both of which are located approximately at mid body, rather than at- or near the pharyngo-intestinal junction as occur in the other species of the genus. Additional differences with congeners are discussed and a key to the Paraturbanella species is provided, in the hope it will be useful to both gastrotrich experts and marine ecologists who discover these microscopic metazoans during their research.

A new population of velvet worms (Onychophora) inhabiting a lava tube cave in the island of Santa Cruz, Galapagos, is reported here. The population size is large, suggesting that they may be troglophilic. Its members are darkly pigmented, with no obvious troglomorphic features. Their 16S rRNA sequence showed no differences when compared to an unidentified species of surface velvet worm from the same island, thus supporting cave and surface populations belong to the same species. Based on the 16S rRNA data, the Galapagos velvet worms derived from an Ecuadorian/Colombian clade, as would be expected of ease of dispersal from the nearest mainland to the Galapagos Islands.

The Painted Rocksnail, currently known as Leptoxis taeniata, is a federally threatened species native to the Mobile River basin in Alabama, USA. Presently restricted to four disjunct populations, the species is at considerable risk of extinction after a range decline of over 95% in the 20th century because of habitat alteration following impoundment of the Coosa River. Here, we reassess the identity and historical range of the Painted Rocksnail to improve communication and conservation efforts for the species. We determined that L. taeniata is a synonym of L. picta and that the name L. taeniata has been misapplied to the current concept of the Painted Rocksnail for which L. coosaensis is the oldest available name. Leptoxis coosaensis and L. picta are herein redescribed. After examination of historical material, we determined that records of the Painted Rocksnail outside the Coosa River drainage were misidentifications. Thus, we redefine the historical range of the Painted Rocksnail as restricted to the Coosa River and select tributaries above the Fall Line at Wetumpka, Alabama, rather than extending into the Alabama River as previously thought. Leptoxis coosaensis is in dire need of conservation, and management plans should take into consideration the revised historical range of the species.

Three new species of the genus Carychium O.F. Müller, 1773, Carychium hardiei Jochum & Weigand, sp. n., Carychium belizeense Jochum & Weigand, sp. n. and Carychium zarzaae Jochum & Weigand, sp. n. are described from the Southeastern United States, Belize and Panama, respectively. In two consecutive molecular phylogenetic studies of worldwide members of Carychiidae, the North and Central American morphospecies Carychium mexicanum Pilsbry, 1891 and Carychium costaricanum E. von Martens, 1898 were found to consist of several evolutionary lineages. Although the related lineages were found to be molecularly distinct from the two nominal species, the consequential morphological and taxonomic assessment of these lineages is still lacking. In the present paper, the shells of these uncovered Carychium lineages are assessed by comparing them with those of related species, using computer tomography for the first time for this genus. The interior diagnostic characters are emphasized, such as columellar configuration in conjunction with the columellar lamella and their relationship in context of the entire shell. These taxa are morphologically described and formally assigned their own names.

In total, 435 specimens of the Southeast Asian freshwater leech species within the Hirudinidae family were collected from 17 locations of various types of aquatic habitats in northeastern Thailand. They were all morphologically placed within the genus Hirudinaria Whitman, 1886 and there were three distinct species: the common Hirudinaria manillensis, 78.2% of all collected specimens and at all 17 locations, Hirudinaria javanica at 20.3% of collected samples and from five locations and a rarer unidentified morphospecies (Hirudinaria sp.) with six samples from only two locations. The karyotypes of these three species were examined across their range in this study area for 38, 11 and 6 adult specimens of Hirudinaria manillensis, Hirudinaria javanica and Hirudinaria sp., respectively. This revealed different chromosome numbers among all three species, with Hirudinaria javanica having n = 13, 2n = 26, Hirudinaria manillensis lacked one small chromosome pair with n = 12, 2n = 24, and the unknown Hirudinaria sp. differed from any known Hirudinaria karyotypes in exhibiting a higher chromosome number (n = 14, 2n = 28) and a gradual change in size from large to small chromosomes. This suggests that the unknown Hirudinaria sp. is a new biological species. However, phylogenetic analysis based upon a 658 bp fragment of the cytochrome oxidase subunit I gene placed this unknown morphospecies within the Hirudinaria manillensis clade, perhaps then suggesting a recent sympatric speciation, although this requires further confirmation. Regardless, the chromosomes of all three species were asymmetric, most with telocentric elements. A distinct bi-armed chromosome marker was present on the first chromosome pair in Hirudinaria javanica, whilst it was on pairs 1, 2, 3 and 5 in Hirudinaria manillensis, and on pairs 3 and 5 for the unknown Hirudinaria sp.

Leiochrides yokjidoensis sp. n., collected from the sublittoral muddy bottom in southern Korea, is described as a new species. The taxonomic status of the monospecific genus Pseudomastus has been a subject of controversy for many years, as its characteristics overlap those given in recent generic definitions of Leiochrides. The results of a comprehensive review and comparison regarding the two genera, based on previous records showed minor differences. In this study, a detailed description of L. yokjidoensis sp. n. is given and a comparison with closely related species is tabulated and discussed.The taxonomic status of Pseudomastus is discussed and the genus placed in synonymy with Leiochrides.

A new diplommatinid genus, Luzonocoptis Páll-Gergely & Hunyadi, gen. n. is erected for two new species, Luzonocoptis antenna Páll-Gergely & Hunyadi, sp. n. and L. angulata Páll-Gergely & Hunyadi, sp. n. Both species inhabit the northeastern part of Luzon Island, Philippines. The genus Luzonocoptis gen. n. is mostly characterized by a very slender shell with 14–18 whorls, a strongly expanded peristome, an interrupted, weak columellar lamella, the absence of any additional plicae or lamellae, and a rachidian tooth having five cusps.

Magnospina gen. n. was created to relocate species of the dentifera-group from Alona sensu lato (Crustacea: Cladocera) and include Magnospina dentifera comb. n. and Magnospina siamensis comb. n. The synapomorphies of the Magnospina gen. n. are (1) basal spines longer than 2/3 of the postabdominal claw, (2) presence of 1–4 large denticles, broad at their bases, protruding downwards, without setules between them. Morphological traits such as habitus, rostrum and postabdomen shape, armature of IDL setae, number of setae on the exopod of limb III are also important in the distinction between Magnospina gen. n. and other genera from the Coronatella-branch. The morphology of Magnospina dentifera comb. n. male confirms the closer relationship with the clade composed by the elgans-group from Alona sensu lato, Ovalona and Leberis, but the external morphology, morphology of the postabdominal claw, basal spine and setae 2–3 of IDL support their separation from any of the group cited. It is concluded that the Coronatella-lineage of Aloninae is composed of the genera Coronatella, Anthalona, Karualona, Bergamina, Extremalona, Ovalona, Celsinotum, Leberis and Magnospina gen. n. The elegans-group from Alona sensu lato also belongs to Coronatella-lineage, but still need formal allocation.

A new genus of troglobitic Carychiidae Jeffreys, 1830 is designated from Nodong Cave, North Chungcheong Province, Danyang, South Korea. This remarkable find represents a great range extension and thus, a highly distant distribution of troglobitic Carychiidae in Asia. The Zospeum-like, carychiid snails were recently included, without a formal description, in records documenting Korean malacofauna. The present paper describes Koreozospeum Jochum & Prozorova, gen. n. and illustrates the type species, Koreozospeum nodongense Lee, Prozorova & Jochum, sp. n. using novel Nano-CT images, including a video, internal shell morphology, SEM and SEM-EDX elemental compositional analysis of the shell.

The minute (adult size 1.3–4.8 mm) land snail species of the family Diplommatinidae in the Fiji archipelago are revised based on historical material and modern (1998–99) collections targeting limestone outcrops on the largest island, Viti Levu, and several smaller islands in the Lau group. The forty-two species (including 30 new species) belong to the genera Moussonia Semper, 1865, Palaina Semper, 1865 and Diancta Martens, 1867, which are briefly characterized and keyed. The diagnostic structure of the inner lamellar system of each species is illustrated. All species except one are endemic to Fiji. In Viti Levu, the 12 localities surveyed each had 1–13 (average 5) species of Diplommatinidae; ten species were each found at a single site only. In the Lau islands, five islands were visited, with 1–4 species per island; four species are known from single islands. The number of historically known species not recollected in 1998–99 (7 species), the number of single-site occurrences (14 species), and the numerous islands — including limestone islands — that have not been surveyed at all, indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna. Such numbers approach the diplommatinid diversity of Palau (39 described and more than 60 undescribed species), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area (New Caledonia, Vanuatu, Samoa). Nomenclatural acts: Lectotypes designated: Diplommatina fuscula, Diplommatina fuscula var. vitiana, Diplommatina godeffroyana, Diplommatina godeffroyana var. latecostata, Diplommatina tuberosa, Diplommatina martensi var. macrostoma, all Mousson, 1870. Neotypes designated: Diplommatina subregularis, Diplommatina ascendens, Diplommatina quadrata, all Mousson, 1870. New species: Diancta aurea sp. n., Diancta aurita sp. n., Diancta basiplana sp. n., Diancta controversa sp. n., Diancta densecostulata sp. n., Diancta dextra sp. n., Diancta dilatata sp. n., Diancta distorta sp. n., Diancta pulchella sp. n., Diancta rotunda sp. n., Diancta subquadrata sp. n., Diancta trilamellata sp. n., Moussonia acuta sp. n., Moussonia barkeri sp. n., Moussonia brodieae sp. n., Moussonia longipalatalis sp. n., Moussonia minutissima sp. n., Moussonia obesa sp. n., Moussonia polita sp. n., Moussonia uncinata sp. n., Moussonia vitianoides sp. n., Palaina alberti sp. n., Palaina flammulata sp. n., Palaina glabella sp. n., Palaina kitteli sp. n., Palaina labeosa sp. n., Palaina parietalis sp. n., Palaina sulcata sp. n., Palaina truncata sp. n., Palaina tuberosissima sp. n.

The minute troglobitic species, Zospeum isselianum Pollonera, 1887 (Eupulmonata: Ellobioidea, Carychiidae) is widely distributed within its Southern Alpine-Dinaric range. Its broad distribution and highly variable shell has caused this species to be historically lumped into its current taxonomic state of ambiguity. In an integrative taxonomic approach, phenotypic and genotypic data are synthesized to assess the intraspecific variability recently inferred for this taxon. We collected 16 Zospeum specimens in the Slovenian Alpine Arc encompassing the type locality for Z. isselianum. The material comprises five morphologically recognized (sub)species. The species are re-evaluated using SEM, X-ray nanotomography (nano-CT), conchological, histological and molecular data. Four well-defined lineages are present, which can be attributed to i) Z. isselianum s.str. from its new type locality (Turjeva jama), ii) a highly morphologically variable lineage that so far cannot be attributed to a single morphospecies, iii) Z. kupitzense A. Stummer, 1984 (raised to species rank) and iv) a lineage comprising the two subspecies Z. alpestre alpestre (Freyer, 1855) and Z. alpestre bolei Slapnik, 1991 plus Z. isselianum individuals. The latter is treated as a single taxon Z. alpestre. After considering the severely degraded syntype material of Zospeum isselianum, we provide a taxonomic re-description and propose aneotype for this species. Furthermore, new diagnostic information is revealed regarding the columella of Zospeum isselianum and allied species. Detailed anatomical study reveals new structural aspects of Zospeum morphology and provides groundwork for future investigations.

Knowledge about the marine malacofauna in the Magellan Region has been gained from many scientific expeditions that were carried out during the 19th century. However, despite the information that exists about molluscs in the Magellan Region, there is a lack of studies about assemblages of molluscs co-occurring with macroalgae, especially commercially exploitable algae such as Gigartina skottsbergii, a species that currently represents the largest portion of carrageenans within the Chilean industry. The objective of this study is to inform about the richness, systematics, and distribution of the species of molluscs associated with natural beds in the Strait of Magellan. A total of 120 samples from quadrates of 0.25 m2 were obtained by SCUBA diving at two sites within the Strait of Magellan. Sampling occurred seasonally between autumn 2010 and summer 2011: 15 quadrates were collected at each site and season. A total of 852 individuals, corresponding to 42 species of molluscs belonging to Polyplacophora (9 species), Gastropoda (24), and Bivalvia (9), were identified. The species richness recorded represents a value above the average richness of those reported in studies carried out in the last 40 years in sublittoral bottoms of the Strait of Magellan. The biogeographic affinity indicates that the majority of those species (38%) present an endemic Magellanic distribution, while the rest have a wide distribution in the Magellanic-Pacific, Magellanic-Atlantic, and Magellanic-Southern Ocean. The molluscs from the Magellan Region serve as study models for biogeographic relationships that can explain long-reaching patterns and are meaningful in evaluating possible ecosystemic changes generated by natural causes or related to human activities.

A new species of pycnogonid collected by the Chinese research vessel, R/V HY IV, during deep sea cruises to the South China Sea in 2013, is described. The new species, Hemichela nanhaiensis, obtained from more than 1300 m depth, is distinguished from the other two species in the genus by the characters of the chela dactylus with 12 denticulations on the inner margin and by the presence of taller tubercles on the lateral processes.

It has come to our attention that in the work referenced above Figure 7A, B is INCORRECT: The CORRECT one is as follows