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Light micrographs showing details of trunk morphology in Centroderes impurus sp. nov. A, C, E: holotype, ZRC.MIS.0001, male stage-2; B, D, F: paratype, KIN-846, putative J6 or adult stage-1 of unknown gender. A, Segments 3-6, lateral view, with dashed circles indicating laterodorsal and lateral accessory sensory spots. B, Segments 1-3, lateral view, showing ventrolateral tube on segment 2, which is found only in this stage and not in male stage-2. C, Segments 10 and 11, lateral view, showing crenulated spines in middorsal position on segment 10. D, Segments 5-6, lateral view, showing indications of lateroventral tube on segment 5, which is found only in this stage and not in male stage-2. E, Segment 8-11, lateral view, showing crenulated spines in midlateral positions on segment 10; note the conspicuous difference between the lateroventral spines on segment 8 and segment 9; dashed circles indicate laterodorsal and lateral accessory sensory spots. F, Segment 8-11, lateral view, showing acicular spines in middorsal and midlateral positions on segment 10. Abbreviations: lass, lateral accessory sensory spot; ldss, laterodorsal sensory spot; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvs, lateroventral spine; lvt, lateroventral tube; mdac, middorsal acicular spine; mdcr, middorsal crenulated spine; mlac, midlateral acicular spine; mlcr, midlateral crenulated spine; vlt, ventrolateral tube; vms, ventromedial spine.
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The kinorhynch fauna of Singapore, or from any locality close by, has never been explored. For the
present study, samples of Kinorhyncha were collected at seven localities around Singapore. This revealed the presence of at least nine different species distributed across four genera. Two species, Echinoderes tchefouensis and Condyloderes paradoxus,...
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Context 1
... the cuticle surface (Fig. 4D). Minute, densely distributed cuticular hairs are present on the posterior half of the segment. Segment 2 and all remaining segments consist of one tergal and two sternal plates. A middorsal spine is present in all specimens. Furthermore, minute ventrolateral tubes were observed in the putative J6 or stage-1 specimens (Fig. 5B). In male stage-2 no such structure was observed neither in LM nor in SEM; in the single specimen examined with SEM it was evident that the position where the tube would attach was filled with densely arranged prominent hairs. Similar hairs were spotted on other segments as well ( (Figs. 2, 5A). Cuticular hairs as on preceding segment. ...
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... were observed in the putative J6 or stage-1 specimens (Fig. 5B). In male stage-2 no such structure was observed neither in LM nor in SEM; in the single specimen examined with SEM it was evident that the position where the tube would attach was filled with densely arranged prominent hairs. Similar hairs were spotted on other segments as well ( (Figs. 2, 5A). Cuticular hairs as on preceding segment. Fig. 2. Line art illustration of Centroderes impurus sp. nov. male stage-2, lateral view. Abbreviations: ij, intersegmentary joint line; lass, lateral accessory sensory spot; ldss, laterodorsal sensory spot; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lv, lateroventral ...
Context 3
... 5 with middorsal acicular spine. Minute lateroventral tubes are present in putative J6 or stage-1 specimens (Figs. 4E, 5D). Stage-2 specimens without such tubes, and instead with densely arranged prominent hairs in the areas where the tubes would attach (Fig. 4F). Sensory spots are present in paradorsal and laterodorsal positions (Figs. 2, 5A). Cuticular hairs as on preceding segment. The midterminal spine is considerably longer than the other spines on this segment (Table 2). Two pairs of subdorsal sensory spots, one pair being more anterior than the other, are present. The whole cuticular surface is covered with minute cuticular hairs which turn slightly longer and denser ...
Citations
... Nevertheless, it should be stressed that these spines are extremely minute and might easily be overlooked due to the dense cuticular hair covering, especially during LM examination. But even if the presence of lateral spines on segment 7 had gone unnoticed among the nine species of the E. coulli group with a middorsal spine on segment 4 (i.e., E. annae Sørensen et al., 2016, E. cyaneafictus Cepeda et al., 2022, E. maxwelli (Omer-Cooper, 1957, E. ohtsukai Yamasaki & Kajihara, 2012, E. parthenope Cepeda et al., 2022, E. regina Yamasaki, 2016, E. rex Lundbye et al., 2011, E. serratulus Yamasaki, 2016and E. teretis Brown, 1999in Adrianov & Malakhov 1999, only E. annae shows the absence of lateral spines (Omer-Cooper 1957;Adrianov & Malakhov 1999;Lundbye et al. 2011;Yamasaki & Kajihara 2012;Sørensen et al. 2016a;Yamasaki 2016;Cepeda et al. 2022). However, other conditions in E. annae make this species easily distinguishable from E. blazeji. ...
... There are several species with two pairs of tubes, in laterodorsal and lateral accessory positions as observed in, e.g., E. abbreviatus Higgins, 1983, E. belenae Pardos et al., 2016or E. intermedius Sørensen, 2006 or in subdorsal and lateral accessory positions as found in E. capitatus (Zelinka, 1928) and E. isabelae G a Ordóñez et al., 2008al., (Zelinka 1928Higgins 1983;G a Ordóñez et al. 2008;Sørensen 2006;Pardos et al. 2016b); nevertheless, the most common tube pattern is the presence of only one pair of tubes on segment 8, typically in a sublateral or lateral accessory position. Furthermore, E. landersi possesses midlateral tubes on segment 9, which is another relatively rare trait, shared with only four species, i.e., E. andamanensis Higgins & Rao, 1979, E. annae, E. newcaledoniensis Higgins, 1967and E. serratulus (Higgins 1967Higgins & Rao 1979;Sørensen et al. 2016a;Yamasaki 2016). ...
Limited data are available for the kinorhynch fauna from the Southern Hemisphere, with little or no data from New Zealand. Here, we provide a first comprehensive overview of the diversity of mud dragons, with an emphasis on species of Echinoderes from the continental slope of New Zealand, from a variety of habitats such as slopes, canyons and seamounts located in the Hikurangi Margin region. The study revealed fifteen species of Echinoderes. Of these, ten are described as new to science: E. aragorni sp. nov., E. blazeji sp. nov., E. dalzottoi sp. nov., E. frodoi sp. nov., E. galadrielae sp. nov., E. gandalfi sp. nov., E. landersi sp. nov., E. leduci sp. nov., E. legolasi sp. nov. and E. samwisei sp. nov. Moreover, Echinoderes juliae Sørensen et al., 2018, Echinoderes sp. aff. E. balerioni, Echinoderes sp. aff. E. galadrielae/beringiensis, Echinoderes sp. aff. E. lupherorum and Echinoderes sp. aff. E. unispinosus are reported in the investigated region. The most abundant among all was E. gandalfi sp. nov., but it was found only in canyons. Interestingly, the second most common species was E. juliae that was found at several stations in canyons, seamount and on the slope. This species is one of the deep-sea species originally found on the abyssal plain off Oregon and along the continental rise off California, Northeast Pacific, recorded in polymetallic nodules in the tropical eastern Pacific, and recently found on the abyssal plains off Chile, east of the Atacama Trench. These findings, together with records of Echinoderes sp. aff. E. lupherorum and Echinoderes sp. aff. E. unispinosus indicate that, despite their low dispersal abilities, kinorhynchs, similar to other meiofaunal species, may exhibit a wider distribution pattern than previously assumed. The number of recorded species and numerous new species show that New Zealand sediments not only are inhabited by a diverse kinorhynch fauna, but Echinoderes, the most speciose genus, still holds much to discover.
... 160 species, representing the most species-rich taxon in Kinorhyncha (Adrianov and Maiorova, 2020;Cepeda et al., 2020;Grzelak et al., 2021;Rucci et al., 2022;Sørensen et al., 2015Sørensen et al., , 2020Sørensen et al., , 2021Yamasaki et al., 2020a, b). Echinoderid species have been recorded worldwide, from tropical to polar areas and from various environments such as intertidal flats, sandy beaches, sandy/muddy shallow bottoms, deep-sea floors, seamounts, and submarine caves (e.g., Grzelak et al., 2021;Neuhaus, 2013;Sørensen et al., 2016;Yamasaki, 2016;Yamasaki et al., 2019;Yıldız et al., 2017). The recent phylogenetic, total-evidence, and phylogenomic analyses supported the family to solely represent the order Echinorhagata; Echinoderidae/Echinorhagata, Kentrorhagata, and Xenosomata comprise one of the two kinorhynch classes, Cyclorhagida, and within this class Echinoderidae/Echinorhagata is a sister taxon of Kentrorhagata; together these clades represent the sister group of Xenosomata (Dal Zotto et al., 2013;Herranz et al., 2022;Sørensen et al., 2015;Yamasaki et al., 2013). ...
A new species Polacanthoderes shiraseae sp. nov. from three Antarctic regions (off Cape Darnley, off Totten Glacier, and in Lützow-Holm Bay) is described. In addition, type species of Polacanthoderes, Polacanthoderes martinezi, is redescribed. The new species is distinguished from P. martinezi by the presence of conspicuously thick lateroventral acicular spines on segments 8 and 9 and the presence of sublateral small acicular spines on segment 7. Both P. martinezi and P. shiraseae sp. nov. occasionally show intraspecific morphological variations in the position of some small acicular spines. The K2P genetic distances based on the mitochondrial cytochrome c oxidase subunit 1 gene sequences in P. shiraseae sp. nov. are 0–1.5%, equivalent to those in other echinoderid species. Phylogenetic analyses of Polacanthoderes based on the nuclear 18S rRNA and 28S rRNA gene sequences support the inclusion of the genus in Echinorhagata/Echinoderidae and suggest that the genus represents the most basal group of this order/family.
... Mangrove mud dragons from Mayotte 2 species adapted to highly fluctuating estuarine habitats with an enlarged nephridiopore (Otsmann et al., 2012;Yamasaki & Fujimoto, 2014). The group currently comprises 13 species: E. annae Sørensen et al., 2016;E. applicitus Otsmann et al., 2012;E. ...
... All the members from the Echinoderes coulli-group share the following characters (which are considered as synapomorphies) (Yamasaki & Fujimoto, 2014;Sørensen et al., 2014Sørensen et al., , 2016Randsø et al., 2019): ...
... This feature is shared by E. ajax Sørensen, 2014, E. annae Sørensen et al., 2016, E. ohtsukai Yamasaki & Kajihara, 2012, E. regina Yamasaki, 2016, E. rex Lundbye et al., 2011and E. serratulus Yamasaki, 2016 Regarding the lateral series of appendages throughout segments 5-8, Echinoderes sp. 1 possesses lateroventral tubes on segments 5 and 8 and sublateral spines on segments 6-7. This fact allows its differentiation from E. annae and E. ohtsukai, which lack spines on segments 6-7 (Yamasaki & Kajihara, 2012;Sørensen et al. 2016). Additionally, E. annae has midlateral tubes on segment 9 and several type 2 glandular cell outlets throughout segments 2-8, which are absent in (Lundbye et al. 2011;Yamasaki, 2016). ...
Mangroves are a challenging and extreme habitat. Since they are relevant for humans, different anthropogenic pressures affect them. In this study, the Kinorhyncha populations inhabiting a moderately impacted mangrove in Mayotte Archipelago (south-western Indian Ocean) are studied. Two species of the genus Echinoderes were found in the studied area, and their unique combination of morphological characters seems to indicate they are undescribed species. These species are characterized by having an enlarged sieve-plate (nephridiopore) consisting of an anterior, convex area with numerous pores and a posterior, concave region with a single pore. This feature, together with the fact of living in an intertidal environment affected by strong salinity fluctuations, suggest their affiliation to the so-called Echinoderes coulli-group. The studied Kinorhyncha populations seem not to be particularly affected by the sewage emissions from nearby towns. Evidence for significant differences in density or richness between the areas more impacted by this pollution and the less impacted areas was not found, but differences in the community species composition seem to be present. However, further analysis including more samples and quantitative ecological data are needed in order to confirm this assumption.
... nov. in having the middorsal acicular spines on segments 4 and 6: Echinoderes aff. bispinosus reported from the coast of Turkey by Sönmez et al. (2016) and Echinoderes sp. 1 from Singapore by Sørensen et al. (2016). Although the former was identified as 'E. ...
... aff. bispinosus' in the original record by Sönmez et al. (2016), Sørensen et al. (2016) suggested 'E. aff. ...
... nov. differs from the two at least in the presence of the type-2 gland cell outlets in subdorsal and lateral accessory positions on segment 2 (Sönmez et al., 2016;Sørensen et al., 2016). In addition, E. uozumii sp. ...
Three new species of echinoderid kinorhynchs are described from Daidokutsu, a submarine cave in Ryukyu Islands, Japan. Echinoderes gama sp. nov. is characterized by the presence of middorsal acicular spines on segments 4–8; lateroventral acicular spines on segments 7–9; lateroventral tubes on segment 5; sublateral tubes on segment 8; laterodorsal tubes on segment 10; and type-2 gland cell outlets in subdorsal and lateroventral position on segment 2. Echinoderes kajiharai sp. nov. is defined by the presence of middorsal acicular spines on segments 4, 6, 8; lateral accessory acicular spines on segment 9; lateroventral acicular spines on segments 6–8; lateroventral tubes on segments 2 and 5; midlateral tubes on segment 10; and type-2 gland cell outlets in laterodorsal position on segments 2 and 5, and subdorsal position on segments 8 and 9. Echinoderes uozumii sp. nov. is characterized by the presence of middorsal acicular spines on segments 4 and 6; lateroventral acicular spines on segments 6–9; lateroventral tubes on segments 2 and 5; sublateral tubes on segment 8; laterodorsal tubes on segment 10; type-2 gland cell outlets in subdorsal and lateral accessory position on segment 2; and blunt, short pectinate fringe teeth of primary pectinate fringe on segment 1. In addition, the Echinoderes multiporus species group including E. kajiharai sp. nov., and the Echinoderes bispinosus species group including E. uozumii sp. nov. are established. Furthermore, the distribution of the two species groups and the origin of Echinoderes species in Daidokutsu are discussed
... The sex of species of Condyloderes has been misidentified in at least some specimens of almost all described species except C. kurilensis and C. storchi (for which only a single male is known; Table 1). The key characters to distinguish the female from the male, viz, the ventromedial appendage at least on segments 7 and 8 as well as the ventromedial area of micropapillae on segment 9, were not recognized in several studies (McIntyre 1962;Higgins 1969;Adrianov et al. 2002;Sørensen et al. 2016). Sørensen et al. (2010b) recognized and described these characters for the first time for a species of Condyloderes and regarded them as species-specific characters, also because they mistook several females as males (see also chapter Comments about selected morphological characters). ...
The description of a new representative of the species-poor genus Condyloderes Higgins, 1969 from the Northeast Pacific (Alaska) is reported. The analyzed specimens of Condyloderes shirleyi sp. nov. showed a significant variation of numerous morphological characters, along with female-specific traits known also from other congeneric species. These findings stimulated the re-investigation of the type material of the six species of Condyloderes described so far, i.e., C. kurilensis Adrianov & Maiorova, 2016, C. megastigma Sørensen, Rho & Kim, 2010b, C. multispinosus (McIntyre, 1962) Higgins, 1969, C. paradoxus Higgins, 1969, C. setoensis Adrianov, Murakami & Shirayama, 2002, and C. storchi Higgins, 2004 in Martorelli & Higgins, 2004. Our study allowed to reveal various morphological novelties and to emend the diagnosis of these species and of the genus Condyloderes. Furthermore, our analysis led to synonymize C. megastigma with C. setoensis. The results of our investigation about the significant variation in C. shirleyi sp. nov. raise a wider question on species identity within Kinorhyncha, underscoring the necessity, if possible, to describe new species from a higher number of specimens and to concentrate on the morphological variation of the going-to-be-described species.
... Nordhaus Echinoderes coulli Higgins, 1977; Echinoderes hwiizaa Yamasaki & Fujimoto, 2014; Echinoderes komatsui Yamasaki & Fujimoto, 2014; Echinoderes marthae Sørensen, 2014;Echinoderes maxwelli Omer-Cooper, 1957; Echinoderes ohtsukai Yamasaki & Kajihara, 2012;Echinoderes regina Yamasaki, 2016; Echinoderes rex Lundbye, Rho & Sørensen, 2011; Echinoderes serratulus Yamasaki, 2016; Echinoderes strii Pardos, Herranz & Sánchez, 2016; Echinoderes teretis Brown, 1985 in Adrianov andMalakhov (1999). All species are found in intertidal marine or brackish water mud flats, except E. regina, E. rex and E. serratulus, which are strictly marine and found only in the near-shore subtidal zone at depths of 10-13 m (Lundbye et al. 2011;Yamasaki 2016b).The monophyly of the species group can hardly be doubted, and is supported by several characters potentially synapomorphic for the group, or clades within the group: (1) middorsal spines absent or, if present, reduced to a short spine on Segment 4 only; (2) lateroventral spines either absent, or present simultaneously on Segments 6 and 7; (3) lateral tubes present on Segments 5 and 8; (4) lateral terminal accessory spines either absent or strongly reduced; (5) sieve plate enlarged with a large posterior pore, present laterally on Segment 9 (Sørensen 2014;Sørensen et al. 2016a;Yamasaki and Fujimoto 2014). Furthermore, three species (Echinoderes aspinosus Sørensen, Rho, Min, Kim & Chang, 2012; Echinoderes bengalensis (Timm, 1958) and Echinoderes caribiensis Kirsteuer, 1964) may very well be considered part of the group, because of their complete lack of middorsal spines, intertidal habitat and the large sieve plate found in E. aspinosus (an examination would be needed to determine whether the two others have large sieve plates as well, but type material no longer exists). ...
Kinorhyncha is a phylum of microscopic, benthic marine invertebrates found throughout the world, from the Arctic to Antarctica and from the intertidal zone to the deep sea. Within the most species-rich genus, Echinoderes, we find a putatively monophyletic species group, the so-called Echinoderes coulli-group. The remarkable morphological similarities of the E. coulli-group species and the fact that the group has a global distribution even though most of the species are restricted to intertidal habitats, has led to the hypothesis that dispersal and speciation within the group has been driven by the process of continental drift. However, this has never been confirmed empirically. With morphology and two molecular loci, COI and 18S, we calculated phylogenetic trees by analysing datasets separately and in combination using Maximum Parsimony, Maximum Likelihood and Bayesian Inference. Using different models of evolution in combination with different statistical approaches, we show that two major clade divergences were consistent with historic drifting of continents, suggesting that vicariance has played an important role for the speciation within the E. coulli-group. Furthermore, we found that reconstructions of past tectonic drifting since the Devonian (416–359 million years ago) were able to explain present species distributions, and suggest that the group originated in a supposedly vast shallow marine environment in north-eastern Gondwana by the mid-late Silurian, 426–416 million years ago.
... We were intrigued to find 2 kinorhynch (mud dragon) OTUs in every core examined, as they are typically thought of as common, but not dominant or highly abundant, meiofauna constituents. However, a kinorhynch species belonging to Echinoderes has been found in both the eastern and western portions of the Gulf of Mexico (Sørensen & Landers 2014) and E. tchefouensis has been reported in geographic regions from Singapore to the Korean Peninsula to Saipan Islands (Sørensen et al. 2012(Sørensen et al. , 2016. Given this, kinorhynchs appear to have the potential to be found over a broad range, and these taxa are clearly relatively abundant if they are being recovered from every core over a geographic range of 5500 km. ...
Meiobenthic organisms, consisting of meiofauna and benthic microeukaryotes, are key components of marine ecosystems and facilitate bentho-pelagic coupling. However, their bio-geographic ranges and dispersal abilities are poorly known, especially in Antarctic waters where knowledge is extremely limited. Many Antarctic marine invertebrates are reported to have circumpolar distributions despite lecithotrophy and brooding development being common. Similarly, most meiofauna have developmental stages that are often assumed to have limited dispersal capabilities. To assess Antarctic meiobenthic community distribution patterns and diversity, the hypervariable V9 region of the 18S small subunit ribosomal RNA (SSU rRNA) gene was used to metabarcode shelf sediment samples (water depth 223 to 820 m) across a 5500 km region of the Western Antarctic. We found that some taxa had broad geographic distributions given that 28 operational taxonomic units (OTUs) were present in every core processed, 74 OTUs were found at every sampling event, and 722 OTUs were present in all of the major water basins sampled. Among these broadly distributed OTUs, metazoan taxa from 4 phyla (annelids, arthropods, kinorhynchs, and nematodes) were dominant members. As many of these OTUs relate to taxa expected to have limited dispersal capabilities based on current life history information, these results highlight our limited understanding of how small organisms move around in the sea. We also noted that the Antarctic Peninsula hosts a strikingly different and less diverse community than higher latitude regions, in contrast to benthic macrofauna.
... On the other hand, no other species of Echinoderes shows a distribution as wide as this. Even though a species like Echinoderes tchefouensis Lou, 1934 is known to have a considerable distribution, and can be found throughout East Asia and Indonesia (Sørensen et al. 2016b), its distribution still covers a smaller geographic area than the one suggested for E. unispinosus, and the distribution of Dorsolateral overview. C. Segments 1 to 2, laterodorsal view. ...
The bathyal kinorhynch fauna along the Northwest American continental rise is explored, with emphasis on species of Echinoderidae Zelinka, 1894. Seven species of Echinoderes Claparède, 1863 are described as new to science: E. anniae sp. nov., E. dubiosus sp. nov., E. hamiltonorum sp. nov., E. hviidarum sp. nov., E. juliae sp. nov., E. lupherorum sp. nov. and E. yamasakii sp. nov. Three known species, Echinoderes hakaiensis Herranz, Yangel & Leander, 2017, E. cf. unispinosus Yamasaki, Neuhaus & George, 2018 and Fissuroderes higginsi Neuhaus & Blasche, 2006, are reported. The numerous new species indicate that the deep-sea still holds a great, undiscovered diversity of kinorhynchs, and that Echinoderes, as is also the case in more shallow, coastal waters, represents an important component of the deep-sea kinorhynch fauna. The presence of E. hakaiensis in the deep-sea sediments demonstrates that the species may occur at a great depth range, and suggests that depth may play a less important role for the distribution of some kinorhynch species. The finding of the Northeast Atlantic species E. cf. unispinosus and the Southwest Pacific species Fissuroderes higginsi could indicate that kinorhynch species in the deep-sea may cover considerably larger distributional ranges than is assumed for coastal species of Echinoderidae.
... There are few other kinorhynchs which have been reported to show either a geographically or a bathymetrically wide distribution. Species with a geographically wide distribution are e.g., Ce. barbanigra found in the Gulf of Mexico, the Caribbean Sea, Bermuda, and the Dominican Republic at a depth ranging from 2 m to 57.5 m, E. ohtsukai found on both the eastern and western coasts of the Pacific Ocean in the intertidal zone, and E. tchefouensis found in the East China Sea, South China Sea, Celebes Sea, Singapore Strait, and Mariana Islands at a depth ranging from 0 m to 140 m (Sørensen et al. 2012b(Sørensen et al. , 2016Yamasaki and Kajihara 2012;Neuhaus et al. 2014;Herranz and Leander 2016). Species from a bathymetrically wide range are e.g., Echinoderes arlis Higgins, 1966, Echinoderes drogoni Grzelak & Sørensen, 2018, Echinoderes eximus Higgins & Kristensen, 1988, Echinoderes peterseni Higgins & Kristensen, 1988, and Echinoderes rhaegali Grzelak & Sørensen, 2018, all ...
Kinorhynchs rarely show a wide distribution pattern, due to their putatively low dispersal capabilities and/or limited sampling efforts. In this study, a new kinorhynch species is described, Echinoderespterussp. n. , which shows a geographically and bathymetrically wide distribution, occurring on the Karasik Seamount and off the Svalbard Islands (Arctic Ocean), on the Sedlo Seamount (northeast Atlantic Ocean), and on the deep-sea floor off Crete and on the Anaximenes Seamount (Mediterranean Sea), at a depth range of 675–4,403 m. The new species is characterized by a combination of middorsal acicular spines on segments 4–8, laterodorsal tubes on segment 10, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6–9, tufts of long hairs rising from slits in a laterodorsal position on segment 9, truncated tergal extensions on segment 11, and the absence of any type-2 gland cell outlet. The specimens belonging to the populations from the Arctic Ocean, the Sedlo Seamount, and the Mediterranean Sea show morphological variation in the thickness and length of the spines as well as in the presence/absence of ventromedial sensory spots on segment 7. The different populations are regarded as belonging to a single species because of their overlapping variable characters.
... The Echinoderes coulli-group is a putatively monophyletic clade of species within Echinoderes (see, e.g., Sørensen 2014; Sørensen et al. 2016;Herranz & Leander 2016;Pardos et al. 2016;Yamasaki 2016). The species group currently accommodates 14 species, which share the common characters of an enlarged sieve plate and a reduced number of spines which, when present, are very short. ...
... caribiensis Kirsteuer, 1964), the sieve plates consist of a large elongate or triangular pore field anterior to a diskshaped depressed area with a central pore (Lundbye et al. 2011;Ostmann et al. 2012;Yamasaki & Kajihara 2012;Sørensen 2014, unpubl. obs.;Yamasaki & Fujimoto 2014;Sørensen et al. 2016;Yamasaki 2016). However, the sieve plates of E. levanderi consist exclusively of the porous areas, whereas the depressed areas with the central pore are missing. ...
The kinorhynch species Echinoderes levanderi Karling, 1954 is redescribed. The species can now be recognized by the presence of spines in middorsal positions on segments 4–8, and in lateroventral positions on segments 6–9, with lateroventral spines on segment 9 showing sexual dimorphism; tubes in subdorsal and ventrolateral positions on segment 2, in sublateral positions on segments 4 and 8, in lateroventral positions on segment 5, and in laterodorsal positions on segment 10. Furthermore, the enlarged sieve plates on segment 9 make the species highly characteristic. New records of the species extend its distributional range into the Bothnian Bay where the bottom water salinity drops below 5 ppt, which is the lowest salinity recorded for a habitat with kinorhynchs.
