Redescription of Echinoderes levanderi Karling, 1954 (Kinorhyncha: Cyclorhagida) – a kinorhynch tolerant to very low salinities

Abstract

Abstract. 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.

Hadal Mud Dragons: First Insight Into the Diversity of Kinorhyncha From the Atacama Trench

“…nov., with middorsal spines on segments 4 to 8, and tubes/spines in lateroventral positions of segments 5 to 9 is the most common pattern observed among species of Echinoderes and is shared by 44 congeners (Yamasaki et al, 2020). However, when we combine these characters with the presence of subdorsal and ventrolateral tubes on segment 2 we shorten the list to only 3 species, i.e., E. adrianovi Herranz et al (2014), E. levanderi Karling (1954), E. kanni Thormar and Sørensen (2010) (Karling, 1954;Thormar and Sørensen, 2010;Herranz et al, 2014;Sørensen, 2018). Despite the coincidence of spine/tube formula E. mamaqucha sp.…”

“…nov. (63.5%). Most importantly, however, E. levanderi possesses sublateral tubes on segments 5 and 8, very characteristic large sieve plates, pointed tergal extension and extremely well-developed pectinate fringes with very long tips throughout the body (Sørensen, 2018). Echinoderes mamaqucha sp.…”

Echinoderes (Kinorhyncha: Cyclorhagida) from the Hikurangi Margin, New Zealand

“…Variation in tube patterns, regarding their presence or absence, has been documented, e.g., in E. daenerysae Grzelak & Sørensen, 2017in Grzelak & Sørensen (2018 for ventrolateral tubes on segment 2, in E. eximus Higgins & Kristensen, 1988 for sublateral tubes on segment 9, in E. levanderi for subdorsal tubes on segment 2, and in E. frodoi sp. nov. (present study) for midlateral tubes on segment 1 (Grzelak & Sørensen 2018;Sørensen 2018). Among specimens of E. landersi, however, one specimen lacks the subdorsal tube on the right side on segment 2 (Fig.…”

“…In our case, all examined females (4 out of 9 specimens in total) had markedly shorter lateral terminal spines than males, which suggests that we might have the same kind of female dimorphism in E. blazeji. Sexual dimorphism expressed in spine lengths has also been reported for E. levanderi Karling, 1954 and the Arctic population of E. pterus Yamasaki et al, 2018, but in these cases it was related to the length of lateroventral spines (Karling 1954;Sørensen 2018;Yamasaki et al 2018a).…”

“…We did not find European Journal of Taxonomy 844: 1-108 (2022) any clear explanation for this intraspecific dimorphism, since the variation in tube pattern was not related to the sexual or developmental stage, neither to intraspecific variation between populations: the presence or absence of tubes were noted for specimens from the same locality. Nevertheless, a variation in spine/ tube pattern in Echinoderidae has recently been documented for several species (e.g., E. arlis Higgins, 1966, E. eximus, E. levanderi and E. rhaegali Grzelak & Sørensen, 2017in Grzelak & Sørensen 2018 and it seems that such morphological variation might be more frequent among Echinoderes species than previously thought (Grzelak & Sørensen 2018Sørensen, 2018).…”