Free-living nematodes from the deep-sea Håkon Mosby Mud Volcano, including the description of two new and three known species * Author Portnova, Daria text Zootaxa 2009 2009-05-11 2096 1 197 213 https://biotaxa.org/Zootaxa/article/view/zootaxa.2096.1.13 journal article 10.11646/zootaxa.2096.1.13 1175-5326 5321670 Terschellingia distalamphida Juario, 1974 Figure 1 , Table 2 Material studied: Three males, five females . Glycerine slides. Males in glycerine slides from Nos. M-1/39 to 1/40; females Nos. M-1/41 to M-1/ 43 in glycerine slides. Locality: Norwegian Sea, Håkon Mosby Mud Volcano, station 283B. Sediment from the pogonophoran fields. Description: Body elongate, slender and fusiform. The anterior end oblique and slightly narrowed. Cuticle optically not striated and smooth. Inner papillae very short, 2 µm in length. Outer labial sensilla invisible. Four cephalic setae, 3–4 µm in length. Amphidial fovea circular and distinctly sclerotized. Diameter of amphids 6 µm, i.e. about 43–50 % of c.b.d. Distance from cephalic end to anterior border of amphidial fovea 13–14 µm (2.8–3.4 of the head diameter), identical for males and females. No cervical setae. Buccal cavity small, narrow, triangular, weakly sclerotized. The width of stoma 3–4 µm in width and 10 µm in length. No teeth in stoma. TABLE 2. Morphometrics of Terschellingia distalamphida Juario, 1974 (all measurements are in µm unless otherwise stated, except ratios a, b, c and c’).

male 1	males (n=2)	females (n=5)
L	1010	872.1–1063	750–937.5
a	32.5	29.1–37.9	22.7–29.3
в	13.2	11.4–13.9	12.3–15.3
с	7.3	2.7–2.8	2.5
V %	32.6–40.8
l.ce.cp.	562.5	500–625	500–566
l.c.s.	3	3	3
diam.c.s.	9	7–8	7–8
st.w.	3	3–4	3–4
amph.w.	6	6	6
diam.amph.	12	13	12–13
dis.amph.	14	13–14	13
diam.n.r.	20	20–21	20–22
diam.bulb.	21	20	20
diam. ca.	27	24–26	24–25
ant. ren.	54.9	54–54.9
diam.midb.	31	28–30	32–33
a.b.d.	24	22–23	20–21
con.t.l.	61.2	61.2	43–55
l.tail	137.7	321.3–382.5	375
c'	5.7	14–17.4	18.8
gub.ap.	9.2	9.2
spic.chord	15.2	12.2–18.3
spic.arch	24.4	24.4
eggs	21–22

Oesophagus narrow, cylindrical and muscular along its entire length, posteriorly forming a pronounced spherical bulb. Intestine gleam well visible. Hypodermal cells of intestine with green granular content. Cardia small, slightly extended. Length of cardia 10–11 µm. Glandular body of the renetta cell porrect, settles down below the cardia, well seen in the light microscope. Excretory pore situated beneath to the nerve ring, 30–35 µm from the posterior end of the bulb. Male reproductive system diorchic, with oustreched anterior testis and reflexed posterior one. Both of them located to the left of the intestine. Unripe spermatozoa are large, oval or triangular–shaped. Spermatozoa in the anterior testis slightly bigger than in the posterior one. Vas deferens long and thin. Spicules paired, equal, arcuate, with cuticle crest, proximally cephalated and tapered distally. Gubernaculum short, with awide caudal apophysis. Precloacal supplements absent. Female reproductive system didelphic, with outstretched ovaries, identical in length, located to the left of intestine. Oviduct contains 3 eggs , the biggest 20–25 µm in size. Tail elongate, with three caudal glands, basal part conical, measuring 61.2 µm in males and 42.7–54.9 µm in females, with threadlike distal part. Conical part of the tail scattered with few somatic setae, 2 µm. No terminal setae at the tip of the tail. Tail length exceeds a.b.d. 17.8 times in both male and female. FIGURE 1. Terschellingia distalamphida Juario, 1974 , details. A: male 1, total view; B: tail region; C: female, cephalic end; D: female, total view. Scale bars: 100 µm. Remarks The Håkon Mosby specimens in general fit the original description of Juario (1974) , except in the case of value “a” which was several times lower in type specimens (a=29.1–37.1 vs. 48.4–64.6) and slight difference in the body length: 872.1–1063 µm vs. 1162–1343 µm.