Campylaimus minutus, Fadeeva, Natalia, Mordukhovich, Vladimir & Zograf, Julia, 2016

Fadeeva, Natalia, Mordukhovich, Vladimir & Zograf, Julia, 2016, RevIsIon of the genus Campylaimus (DIplopeltIdae, Nematoda) wIth descrIptIon of four new specIes from the Sea of Japan, Zootaxa 4107 (2), pp. 222-238 : 229-231

Campylaimus minutus sp. nov.

( Fig. 5 )

Locality: Table 1 .

Measurements. Table 3 .

Material examined. Holotype. Adult male, formalin-fixed, mounted on slide (MN A756 1–2), in glycerin. Allotype. Adult female, formalin-fixed, mounted on slide (MN A256-2), in glycerin. Paratypes. Nine males, slides (A254-3, A262-3, A373-2, A373-1), the Sea of Japan, depth 515–1530 m; ten females, slides (A253-3, A251-2, A265-2, A372-3, A373-1), 10 juveniles, same data as paratypes (table 1).

Etymology. The species name is derived from the Latin “ minutus ”, meaning “small or diminutive”.

Description. Small thread-like worms, body cylindrical over the most of its length, with very weak annulations. Anterior-most annuli posterior to oral opening and cephalic sensilla bases. Anterior end broad, with a clear terminal cap. Oral opening located sub-terminally, on dorsal side of body. Narrow, small buccal cavity. Labial papillae not seen. Four setiform cephalic setae 1.5 µm long; two cephalic setae located at level of the oral opening, others posterior to level of oral opening.

Amphids well developed, comprising 2 parallel limbs connected behind the oral opening; dorsal limb somewhat shorter (25–35µm or 25–44% of pharynx length). Ventral amphidial limb (3–4 µm wide) completely fused with lateral field (4 µm wide). Lateral field comprises two very close lines extending from base of amphid to tail tip. No visible boundary between ventral amphid limb and lateral field.

Pharynx muscular, cylindrical; without bulb. Nerve ring surrounds posterior part of pharynx. Cardia welldeveloped, short, embedded in intestine. Pharyngeal glands indistinct.

Tail similar in shape in both sexes, short, conoid, terminus ventrally curved. Male tail 4.1–5.3 a.b.d., female tail 2.1–5.7 a.b.d. Tail setae not seen.

Male reproductive system diorchic, both testes short, outstretched, opposed. Spicules paired, symmetrical, slender, weakly arcuate, with proximally developed capitulum. Gubernaculum present, plate-like, with paired dorsal arcuate apophysis (2–4 µm).

Females similar to male. Gonads paired, opposed; ovaries outstretched, not reflexed. Anterior and posterior ovaries located on left and right side of intestine, respectively. Vulva a transverse slit, post equatorial (V 54 –60%). Vagina short, not thickened. Two glands surround the vulva.

Diagnosis. Campylaimus minutus sp. nov. is characterized by having a uniformly cylindrical body with weak cuticular annulations, amphids well developed with 2 parallel limbs connected posterior to the oral opening, dorsal limb short (25–44% of pharynx length), ventral limb fully fused with lateral alae of equal width, extending from the base of the amphid to the tail tip. Spicules slender, with proximal capitulums. Gubernaculum plate-like, with dorsal arcuate apophysis.

Differential diagnosis. Campylaimus minutus sp. nov. from the Sea of Japan has the typical form of the amphid, as described in diagnoses of the genus Campylaimus , the ventral limb being fused with a broad lateral field, extending from the base of the amphid to the tail tip.

In the width of the lateral alae (3–4 µm), C. minutus sp. nov. resembles C. gerlachi and C. ponticus . It differs from C. gerlachi in the relative length of the cephalic setae (20 % h. b. d. vs 50%, respectively) and the tail (<5 vs> 5 anal body diameters); it differs from C. ponticus in the length of the spicules (10–21 µm vs 28 µm, respectively) and longer dorsal limb of amphids (22–32 µm vs 11 µm).

Figures

FIGURE 5. Campylaimus minutus sp. nov. A: Anterior end of the male, dorsal view; B: Entire body, male holotype; C: Spicule and gubernaculum, male holotype; D: Posterior end, male holotype; E: Anterior end of the body, female allotype; F: Entire body, female allotype; G: Posterior body region of female. Scale bar: A, C = 10 µm; B, F = 100 µm; D = 20 µm; E, G = 50 µm.

Tables

TABLE 3. Measurements (Μm) of Campylaimus minutus sp. nov. (range, mean value in parentheses).

	HOLOTYPE Male	ALLOTYPE Female	PARATYPES Males N= 9 PARATYPES Females N=10	PARATYPES Females N=10
L	522.8	558.3	323.9–544.4	378.3–558.0
Maximum body diameter	27,61	29.0	17.0–27.0 (21.7)	19.0–30.0 (22.0)
Buccal cavity, length	3.0	3.0	3.00	3.0
Head diameter	8.0	7.0	8.0	7.0–9.0 (8.5)
Cephalic setae, length	1.5	1.5	1.5	1.5
Dorsal limb of amph. fovea	22.0	28.0	25.0–35.0 (23.6)	20.0–32.0 (24.2)
Ventral limb of amph. fovea length
Amphidial fovea width	3	3.0	3.0–4.0	3.0–4.0
Lateral alae	2.5	2.0	2.0–3.0 (2.5)	2.0–4.0
Pharynx, length	81.0	92.0	39.0–103.0 (79.6)	69.0–110.0 (85.2)
Tail, length	78	85.0	61.0–132.0 (78.5)	58.3–94.0 (73.2)
Spicular, length	21.0	-	10.0–21.0 (15.3)
Anal body diameter	18.9	15	13.0–24.0 (16.5)	14.0–28.0 (16.9)
Gubernaculum, length	4.0	-	4.0
		-
a	18.9	19.2	17.0–26.0 (25)	17.1–25.4 (20.2)
b c V, %	6.4 6.7	6.1 5.6 54	4.0–12.0 (6.4) 5.0–7.0 (6.0)	4.7–6.1 (5.3) 4.8–7.9 (6.1) 50–60 (54)