Halichoanolaimus brandtae Julia, Yulia & Olga, 2015, sp. n.

Halichoanolaimus brandtae sp. n.

(Figs 5–7)

Measurements. Table 1.

Material examined. Holotype male: deep-sea (the Sea of Japan), 3358 m with box-corer, found in silt-clay, 0–5 cm profile, collected by Trebukhova Yu. A. on August, 17th 2010. Slide is kept in Museum of A.V. Zhirmunsky Institute of Marine Biology, Vladivostok, Russia (N MIMB 28868).

Paratypes two females and four males (MIMB 28869 and MIMB 28870): same collection data.

Description. Adult males. Body relatively short and stout, anterior end blunt. Cuticle with transverse rows of lateral dots. Amphid spiral, 20 Μm diameter or 35% of head diameter, situated near mid-length of buccal cavity, with 6.5 turns. Inner labial sensillae 6, papilliform and hard to observe. Six outer labial sensillae and four cephalic setae situated in one circle, short. Outer labial sensillae twice length of cephalic setae. Body covered with sparse somatic setae. Buccal cavity typical for genus, consisting of two parts: a wide anterior and a narrowed posterior part. Length of buccal cavity 30–40 µm or 15% of pharynx length. About ten denticles in a set at the border of anterior and posterior parts of the buccal cavity; each set subdivided into two parts by a tooth like structure. Pharynx cylindrical. Cardia not found. Distance from the anterior end to the nerve ring 44% of pharynx length. Distance from the anterior end to the excretory pore 51% of pharynx length. Intestine blind, spicules of swallowed nematodes sometimes found in posterior part of the intestine (Fig. 5 D). Two lateral rows of cuticular pores, 13–15 in a row around the posterior part of intestine (Fig. 6 C). Testes paired, anterior to right of intestine, posterior to left of intestine. Five precloacal supplements, anterior-most 47–55 Μm from cloacal opening. Spicules paired, arcuate, 1.9 cloacal diameters long. Gubernaculum without apophyses, 47–53 Μm long or 1.1 c.b.d. Tail consisting of anterior conoid (25%) and posterior cylindrical (75%) parts. Tail length 181–224 Μm or 4.7 cloacal diameters. A few somatic setae on the cylindrical part of the tail.

Adult female. In general, females similar to males. Reproductive system didelphic with reflexed ovaries. Anterior gonad 123–142 Μm long, posterior 107–140 Μm long. Uterus with two fertilized eggs each 85 Μm in diam.

Diagnosis and relationships. Halichoanolaimus brandtae sp. n. is characterized by the number of amphideal turns, long spicules, five pre-cloacal supplements and long cylindrical part of the tail.

Halichoanolaimus brandtae sp. n. is close to H. minor Saweljev, 1912 and H. quattourdecimpapillatus Chitwood, 1951 but differs from both in morphometrics (Table 3). In addition, the new species differs from H. minor by the number of amphideal turns (6.5 vs 5), length of spicules (81–94 Μm vs 65–70 Μm) and number of precolacal supplements (5 vs 2). Halichoanolaimus brandtae sp. n. differs from H. quattuordecimpapillatus by the number of amphideal turns (6.5 vs 5), length of spicules (81–94 Μm vs 75 Μm) and number of precloacal supplements (5 vs 15).

Etymology. The species name is in honor of Angelica Brandt, organizer of the scientific cruise “SoJaBio” in course of which new species was found.

Remarks. After critical evaluation of the relevant descriptions, we accept 22 valid species (including the new one) in the Halichoanolaimus.

Halichoanolaimus macramphis Gourbault & Vinx, 1985, Halichoanolaimus hinemoae Ditlevsen, 1930, Halichoanolaimus conicaudatus Allgen, 1959, and Halichoanolaimus filipjevi Allgen, 1953 known from females and Halichoanolaimus australis Cobb, 1898 known from juveniles we consider species inquirenda. Halichoanolaimus nemurus Allgen, 1959 and Halichoanolaimus striatilaimus Allgen, 1959 was badly damaged and its description is incomplete (Gerlach, 1964).

Daschenko and Belogurov (1991) described cuticular pores on the body surface of H. bispirae for the first time. The pores were situated on the lateral side of the body, with two rows of 4 pores just behind the nerve ring and two rows of 3–5 pores in the trophico-genital region (i.e. the part of the nematode body containing intestine and reproductive system). In H. brandtae sp. n., we found two lateral rows of 13–15 cuticular pores in the trophico-genital region. The position and external morphology of these pores resembles those described for representatives of the closely related family Cyatholaimidae (Wright & Hope, 1968; Malakhov & Yushin, 1984). It is possible that the number of cuticular pores in the posterior part of the body is diagnostic for species and could be used as an additional feature for species identification. However, due to their small size the pores are hard to see using light microscopy only.