Echinoderes remanei (Blake, 1930)

Grzelak, Katarzyna, Yamasaki, Hiroshi, Mincks, Sarah, Phillips, Anna J. & Sørensen, Martin V., 2023, Revision of an Arctic kinorhynch species: Echinoderes svetlanae and E. tubilak are junior synonyms of E. remanei, Zoologischer Anzeiger 302, pp. 75-89 : 86-88

publication ID

https://doi.org/ 10.1016/j.jcz.2022.11.001

persistent identifier

https://treatment.plazi.org/id/03EB87BD-8510-FFE8-8B69-D84197F46EAF

treatment provided by

Felipe

scientific name

Echinoderes remanei
status

 

4.2. Diagnostic features of E. remanei View in CoL

Echinoderes remanei View in CoL belongs to the most common group of Echinoderes View in CoL regarding its spine pattern. Five middorsal spines and lateroventral tubes/spines on segments 5 to 9 are shared with 46 congeners ( Yamasaki et al., 2020). However, when we combine these characters with the presence of glandular cell outlets type 2 in subdorsal, laterodorsal, midlateral/sublateral and ventrolateral positions on segment 2, we shorten the possibilities to 10 species, i.e., Echinoderes angustus Higgins & Kristensen, 1988 View in CoL , Echinoderes aquilonius Higgins & Kristensen, 1988 View in CoL , Echinoderes beringiensis Adrianov & Maiorova, 2022 View in CoL , Echinoderes cernunnos Sørensen et al., 2012 View in CoL , Echinoderes galadrielae Grzelak and Sørensen, 2022 View in CoL , Echinoderes juliae Sørensen et al., 2018 View in CoL , Echinoderes obtuspinosus Sørensen et al., 2012 View in CoL , Echinoderes pennaki Higgins, 1960 View in CoL , Echinoderes romanoi Landers & Sørensen, 2016 View in CoL , and Echinoderes xalkutaat Cepeda et al., 2019 View in CoL ( Higgins 1960; Sørensen et al., 2012; Landers & Sørensen 2016; Grzelak & Sørensen 2018; Herranz et al., 2018; Sørensen et al., 2018; Cepeda et al., 2019; Adrianov & Maiorova 2022; Grzelak & Sørensen 2022). Nevertheless, E. beringiensis View in CoL , E. cernunnos View in CoL , E. galadrielae View in CoL , E. romanoi View in CoL and E. xalkutaat View in CoL can immediately be distinguished from E. remanei View in CoL by the absence of glandular cell outlets type 2 on segment 4. Instead, E. cernunnos View in CoL shows a pair of glands on segment 7 and very characteristic long and spiniform tergal extensions, while E. romanoi View in CoL and E. xalkutaat View in CoL are (in addition to their lack of gco2 on segment 4) much smaller and show different shapes of tergal extensions ( Sørensen et al., 2012; Landers & Sørensen 2016; Cepeda et al., 2019). E. juliae View in CoL and E. obtuspinosus View in CoL , although possessing a subdorsal pair of glandular cell outlets type 2 on segment 4, have an extra pair of glands on segment 3 ( E. juliae View in CoL ) or can be easily differentiated from E. remanei View in CoL by the presence of very short and stout lateral terminal spines ( E. obtuspinosus View in CoL ) ( Sørensen et al., 2012; 2018).

Of the abovementioned species, E. remanei View in CoL shows a much closer general resemblance with E. aquilonius View in CoL , E. angustus View in CoL and E. pennaki View in CoL . Interestingly, the first two have been described from Disko Island, western Greenland, along with E. tubilak ( Higgins & Kristensen 1988) View in CoL . The latter one, on the other hand, has been described from the San Juan Archipelago in northwest Washington, USA, and belongs to one of the first Echinoderes species described by Higgins (1960). Several years later, the species was redescribed by Higgins (1977) and recently by Herranz et al. (2018). Echinoderes remanei View in CoL share identical spine patterns, distribution of glandular cell outlets type 2, and even midventral partial articulation of segment 2 ( Grzelak & Sørensen 2018; Herranz et al., 2018) with E. aquilonius View in CoL , E. angustus View in CoL and E. pennaki View in CoL ; the only exception is the absence of laterodorsal glandular cell outlets type 2 on segment 10 in E. pennaki View in CoL ; the lack of this trait has been confirmed using SEM by Herranz et al. (2018). Therefore, the easiest and most reliable way to Abbreviation s: LA lateral accessory; LD laterodorsal; LV lateroventral; MD middorsal; ML midlateral; PD paradorsal; PV paraventral; SD subdorsal; SL sublateral; VL ventrolateral; VM ventromedial; ac acicular spine; gco1/2 glandular cell outlet type 1/2; ltas lateral terminal accessory spine; lts lateral terminal spine; pe penile spine; pr protuberance; si, sieve plate; ss sensory spot; tu tube; ♀ female condition of sexually dimorphic characters; 6 male condition of sexually dimorphic characters.

distinguish E. remanei View in CoL from its three congeners is by using morphometric differences in combination with a comparison of the pectinate fringe on segments 1 and 2. Unlike E. remanei View in CoL , none of these species is characterized by the middorsal spine on segment 8 being significantly shorter than the one on segment 7 ( Table 2; Fig. 8 View Fig ) ( Higgins & Kristensen 1988; Herranz et al., 2018). This feature, which is unusual among Echinoderes View in CoL , is consistently found in all individuals in E. remanei View in CoL , irrespective of sampling location. Moreover, E. angustus View in CoL and E. pennaki View in CoL , in contrast to E. remanei View in CoL , do not show significant differences in lateral terminal spine lengths between males and females ( Higgins & Kristensen 1988; Herranz et al., 2018). Even if only the length of spines for males would be compared, both species have longer spines in comparison to those of E. remanei View in CoL (avg. LTSm:> 170 μm vs 149 μm, respectively). Echinoderes aquilonius View in CoL is, however, similar to E. remanei View in CoL in sexual dimorphism expressed in longer lateral terminal spines in males than in females ( Higgins & Kristensen, 1988; own data), but still both species can be distinguished from one another since the lateral terminal spines in E. aquilonius View in CoL are shorter than those in E. remanei View in CoL (avg. LTS ♀: 70 μm vs 90 μm, respectively; avg. LTS 6: 135 μm vs. 149 μm, respectively). In addition, all three species differ from E. remanei View in CoL by being larger (avg.TL: 405–460 μm vs. 369 μm), and having markedly less conspicuous and more uniform midventral pectinate fringe on segment 1 and 2.

It seems that the morphometric pattern for middorsal and terminal spines itself represents a rather unique feature for E. remanei View in CoL . In species of Echinoderes View in CoL segment 8 usually has the longest middorsal spine, or is at least similar in length to the spine on segment 7. Therefore, a significantly shorter spine on segment 8 certainly stands out and distinguishes E. remanei View in CoL among other Echinoderes species. Also, the sexual dimorphism expressed in lateral terminal spine lengths is not a very common trait. According to our knowledge, this trait has only been observed for five other species so far, i.e., E. aquilonius View in CoL , Echinoderes bengalensis ( Timm, 1958) View in CoL , Echinoderes blazeji Grzelak & Sørensen, 2022 View in CoL , Echinoderes coulli Higgins, 1977 View in CoL , and Echinoderes lusitanicus Neves et al., 2016 View in CoL ( Higgins 1977; Higgins & Kristensen 1988; Neves et al., 2016; Grzelak & Sørensen 2022; Sørensen, unpubl. obs). The difference in length due to sexual dimorphism observed in E. remanei View in CoL is very conspicuous ( Table 2; Figs. 2 View Fig and 9 View Fig ) and the size ranges between the sexes never overlapped ( Fig. 9 View Fig ); males were characterized by considerably longer lateral terminal spines than those in females, and this pattern was very consistent for all localities. Consequently, when all morphometric data were taken into account, regardless of sampling location males were plotted closer together and form a distinct group ( Fig. 10 View Fig , left side of the plot) in comparison to females ( Fig. 10 View Fig , right side of the plot). This result only emphasizes that the specimens, despite the large geographic distance between their locations, are indeed morphologically highly similar, and that differences between the sexes are consistent and driven by the length of lateral terminal spines.

Kingdom

Animalia

Phylum

Kinorhyncha

Class

Cyclorhagida

Order

Echinorhagata

Family

Echinoderidae

Genus

Echinoderes

Loc

Echinoderes remanei

Grzelak, Katarzyna, Yamasaki, Hiroshi, Mincks, Sarah, Phillips, Anna J. & Sørensen, Martin V. 2023
2023
Loc

Echinoderes beringiensis

Adrianov & Maiorova 2022
2022
Loc

Echinoderes galadrielae Grzelak and Sørensen, 2022

Grzelak and Sorensen 2022
2022
Loc

E. beringiensis

Adrianov & Maiorova 2022
2022
Loc

E. galadrielae

Grzelak and Sorensen 2022
2022
Loc

Echinoderes blazeji Grzelak & Sørensen, 2022

Grzelak & Sorensen 2022
2022
Loc

Echinoderes xalkutaat

Cepeda 2019
2019
Loc

Echinoderes juliae Sørensen et al., 2018

Sorensen 2018
2018
Loc

Echinoderes romanoi Landers & Sørensen, 2016

Landers & Sorensen 2016
2016
Loc

E. romanoi

Landers & Sorensen 2016
2016
Loc

E. romanoi

Landers & Sorensen 2016
2016
Loc

Echinoderes lusitanicus

Neves 2016
2016
Loc

Echinoderes cernunnos Sørensen et al., 2012

Sorensen 2012
2012
Loc

Echinoderes obtuspinosus Sørensen et al., 2012

Sorensen 2012
2012
Loc

Echinoderes angustus

Higgins & Kristensen 1988
1988
Loc

Echinoderes aquilonius

Higgins & Kristensen 1988
1988
Loc

E. aquilonius

Higgins & Kristensen 1988
1988
Loc

E. angustus

Higgins & Kristensen 1988
1988
Loc

E. aquilonius

Higgins & Kristensen 1988
1988
Loc

E. angustus

Higgins & Kristensen 1988
1988
Loc

E. angustus

Higgins & Kristensen 1988
1988
Loc

Echinoderes aquilonius

Higgins & Kristensen 1988
1988
Loc

E. aquilonius

Higgins & Kristensen 1988
1988
Loc

E. aquilonius

Higgins & Kristensen 1988
1988
Loc

Echinoderes coulli

Higgins 1977
1977
Loc

Echinoderes pennaki

Higgins 1960
1960
Loc

E. pennaki

Higgins 1960
1960
Loc

E. pennaki

Higgins 1960
1960
Loc

E. pennaki

Higgins 1960
1960
Loc

E. pennaki

Higgins 1960
1960
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