Echinoderes arlis, a New Kinorhynch from the Arctic Ocean 
Robert P. Higgins 1 
The first kinorhynch to be reported from 
within the Arctic Circle was Centroderes arcticus 
(Steiner, 1919) new combination. This species 
was originally described in one of several in- 
valid "larval genera," the genus Centropsis 
Zelinka, 1907. Steiner’s description is such that 
if a closer study were possible his species might 
be better assigned to the genus Campyloderes 
Zelinka, 1907, the only other genus in the 
family Centroderidae Zelinka, 1907. 
The family Echinoderidae Biitschli, 1876 has 
been reported from as far north as Bergen, 
Norway (Schepotieff, 1907:134) and the 
northern Baltic Sea (Levander, 1900:19; 
Karling, 1954:189). The southernmost limit 
of this family’s distribution is South Georgia 
Island in the southern Atlantic (Lang, 1949: 
17). Members of the single genus within this 
family, Echinoderes Claparede, 1863, are widely 
distributed and are very common representatives 
of the phylum Kinorhyncha. 
The species described in this paper is the first 
member of the genus Echinoderes reported 
from within the Arctic Circle and is from the 
greatest recorded depth for the phylum. 
Genus Echinoderes Claparede, 1863 
Echinoderes arlis n. sp. 
Figs. 1 and 2 
description: Holotypic female, 420p trunk 
length (trunk length measured between anterior 
margin of segment 3 and posterior margin of 
segment 13) ; msw-10, 85 p (maximum sternal 
width at segment 10 — a measurement across the 
anterior margin of widest sternal plates) ; sw- 
12, 70p (sternal width at segment 12 — a sim- 
ilar measurement) ; trunk length-msw ratio 
4.9:1, trunk length-sw-12 ratio 6.0:1. 
Second segment with 16 anteriorly rounded 
1 Department of Biology, Wake Forest College, 
Winston-Salem, North Carolina. Manuscript received 
July 26, 1965. 
placids, midventral placid truncate, distinctly 
larger than others; trichoscalid plates not ob- 
served. 
Trunk segments (segments 3-13) with 
numerous hairs, often very long, up to 17p, 
pattern distinctive (Figs. 1 and 2). 
Posterior border of each trunk segment with 
pectinate fringe except for terminal tergal plate. 
Middorsal spines long, on segments 6, 8, and 
10, 73p, 92p, and 125p; lateral spines on 
segments 8-11, all approximately 42p in length; 
accessory lateral spines of segment 13, 67 p in 
length, 0.32 X the lateral terminal spines; 
lateral terminal spines 21 Op in length, 0.50 X 
the trunk length. 
Posterior margin of terminal tergal plate 
deeply incised, forming broadly rounded mar- 
gins which abruptly form elongate spinous pro- 
jections (Figs. 1 and 2) ; sternal plates of 
terminal segment with broadly rounded margins 
positioned anterior to the limits of the tergal 
margin. 
Pachycycli (thickened anterior margins of the 
trunk segments) well developed; muscle scars 
prominent only on medial portion of twelth 
sternal plates. 
Pigmented eye-spots not noted due to pres- 
ervation; adhesive tubes 20p in length, on 
ventral surface of segment four, directly anterior 
to tergal-sternal junction of fifth segment. 
Allotypic male, 382p trunk length; msw-10, 
73p; sw-12, 65p; trunk length-msw ratio 
5.2:1, trunk length-sw-12 ratio 5-9:1; flexible 
penis spines 20p in length, originating from 
anterolateral margin of terminal sternal plates; 
accessory lateral spines 40p in length, shorter 
than those of female; lateral terminal spines 
longer than in female, 238p in length, 0.62 X 
trunk length. 
The range in trunk length for all females 
examined was 380-420p; all but the holotype 
were mounted laterally, preventing further 
range measurements concerning width. Lateral 
terminal spines measured 210-224p in length, 
518 
