New findings of deep-sea nematodes of genus Benthimermis Petter, 1980 (Nematoda, Benthimermithidae) with description of seven new species Author Miljutin, Dmitrij M. Russian Federal Research Institute of Fisheries and Oceanography, V. Krasnoselskaja 17, Moscow 107140 (Russia) dmilutin @ mtu-net. ru. text Zoosystema 2004 26 1 21 48 journal article 10.5281/zenodo.5393181 1638-9387 5393181 Benthimermis filiformis Petter, 1987 ( Figs 1-3 ; Tables 1 ; 2 ) Benthimermis filiformis Petter, 1987: 571 , 572, fig. 4. TYPE MATERIAL . — Holotype : Norway Sea , 64°24.3’N , 1°43.9’E , 2615 m , 19.VII.1975 , mature ( MNHN 37 BC); paratypes : Norway Sea , 69°29.2’N , 10°11.6’E , 2957 m , 27.VII.1975 , 1 juvenile ( MNHN 38 BC); Norway Sea , 73°28.2’N , 10°06.6’W , 2973 m , 7.VIII.1975 , 1 mature ( MNHN 54 BC). MATERIAL EXAMINED. — 7 fertile (see Tables 1 and 2 for details). DESCRIPTION Measurements are presented in Table 2 . Only females were found. Body cylindrical, long. Anterior end in shape of rounded cone. Posterior end conical, possessing a terminal spine from 60 to 110 µm long. For most of the specimens, terminal caudal spine completely cuticular with a longitudinally or obliquely striated core, but terminal spine of the specimen No. 6 having a cytoplasmic core with some vesicle-like includings. Cuticle about 2.5 µm thick at anterior and posterior body part, and about 1.5 µm thick at midbody. Cuticle of apical cephalic part thinner (about 1 µm) in some specimens. Stratification of cuticle usually visible at anterior part of caudal spine. Mouth opening absent. Four mediolateral papilloid cephalic setae (1.5-2.0 µm long) insert- ed in tiny pits. Amphids non-spiral. Amphidial aperture looking like a transversally oriented ovals of about 2.0 µm width. Amphidial fovea tubiform. Somatic sensilla appearing as pores connected with hypodermal glands in lateral chords. Such sensilla only found in several specimens. Pharynx looking like a non-muscular string devoid of internal lumen. Midgut a multicellular trophosome devoid internal lumen and consisting of four cells at cross-section ( Fig. 3 ). Cell borders of trophosome clearly visible. Rectum looking like a tube with thin walls. Anus appearing as narrow channel inside cuticle or absent. Female reproductive system didelphic, amphidelphic, occupying about one quarter of all body length. TABLE 1. — Coordinates, depth and dates of collecting of the samples where females of Benthimermis filiformis Petter,1987 were found.

No. of specimen 1		2	3	4	5	6	7
Collection No. MNHN		MNHN	MNHN	MNHN	MNHN	MNHN	MNHN
314 BF	326 BF	359 BF	360 BF	364 BF	377 BF	379 BF
Cruise	MD 32	DEMERABY	WALVIS	WALVIS	WALVIS	BIOVEMA	BIOVEMA
Station	DS 151	KG 10	KG 06	KG 10	CP 06	KG 15	KG 16
Date of collecting	5.IX.1982	16.IX.1980	26.XII.1978	27.XII.1978	30.XII.1978	20.XI.1977	25.XI.1977
Region	Western part of the Indian Ocean	Western Altantic	Southeastern Atlantic	Southeastern Southeastern Atlantic Atlantic		Western Atlantic	Western Atlantic
Coordinates	20°51.0’S 56°03.3’E	8°10.31’N 49°02.98’W	33°54.2’S 05°09.2’E	33°54.7’S 05°09.2’E	33°22.5’S 02°35.9’E	10°47.6’N 42°40.88’W	11°35.8’N 32°51.4’W
Depth	3240- 3300 m	4440 m	5210 m	5210 m	4550 m	5100 m	5880 m

TABLE 2. — Measurements (in µm) of females of Benthimermis filiformis Petter, 1987 .

No. of specimen	1	2	3	4	5	6	7
Body length	4094.0	5516.0	4094.0	4000.0	5375.0	4828.0	4922.0
Maximal body diameter	106.0	111.0	88.0	75.0	136.0	91.0	111.0
Diameter at the level of cephalic sensilla	21.0	17.0	18.0	15.0	22.0	21.0	18.0
Diameter at the level of amphids	60.0	68.0	46.0	44.0	70.0	60.0	59.0
Diameter at the middle of the body	106.0	111.0	83.0	75.0	136.0	88.0	110.0
Diameter at the level of the anus	40.0	43.0	36.0	41.0	64.0	55.0	56.0
Distance from the cephalic end to the amphids	42.0	80.0	56.0	121.0	63.0	83.0	83.0
“a”	38.6	49.7	46.8	53.3	39.5	53.1	44.3
“c”	42.2	43.0	53.9	50.6	37.3	41.6	36.2
“V”, %	55.3	51.8	53.1	52.7	52.6	53.7	55.5

FIG. 1. — Benthimermis filiformis Petter, 1987 , (see Tables 1 and 2 for locations and measurements of specimens); A , reproductive system of specimen No. 3; B , total view of specimen No. 3; C -E , cephalic end of specimen No. 4; F , cephalic end of specimen No. 3; G , tail of specimen No. 4; H , tail of specimen No. 3. Abbreviations: a , amphid; m , somatic musculature; o , oocytes or eggs; ov , ovary; t , trophosome. Scale bars: A, 100 µm; B, 500 µm; C-H, 50 µm. FIG. 2. — Benthimermis filiformis Petter, 1987 , (see Tables 1 and 2 for locations and measurements of specimens); A , cephalic end of specimen No. 1; B , tail of specimen No. 1; C , cephalic end of specimen No. 6; D , tail of specimen No. 6; E , F , cephalic end of specimen No. 2; G , tail of specimen No. 7. Abbreviations: a , amphid; l.ch , lateral hypodermal chord; m , somatic musculature; ph , vestigial pharynx; s.s , hypodermal gland connected with somatic sensillum; t , trophosome. Scale bars: 50 µm. TABLE 3. — Coordinates, depth and dates of collecting of the samples where females of B. hureaui Petter, 1983 were found.

No. of specimen	1	2
Collection No.	MNHN 320 BF	MNHN 325 BF
Cruise	MD 32	DEMERABY
Station	DC 18	KG 08
Date of collecting	14.VIII.1982	15.IX.1980
Region	Western part of the Indian Ocean	Western Atlantic
Coordinates	21°19.0’S 55°15.6’E	8°09.2’N 49°02.6’W
Depth	3150-3225 m	4434 m

TABLE 4. — Measurements (in µm) of females of B. hureaui Petter, 1983 .

Specimen No.	1	2
Body length	3078.0	3172.0
Maximal body diameter	100.0	98.0
Diameter at the level of cephalic sensilla	25.0	20.0
Diameter at the level of amphids	46.0	45.0
Diameter at the middle of the body	100.0	98.0
Diameter at the level of the anus	–	41.0
Distance from the cephalic end to the amphids	29.0	31.0
“a”	30.8	32.4
“c”	–	62.2
“V”, %	56.3	52.2

FIG. 3. — Benthimermis filiformis Petter, 1987 , (see Tables 1 and 2 for locations and measurements), cross-section at level of trophosome of specimen No. 4 (reconstruction based on TEMphotos). Abbreviations: c , cuticle; l.ch , lateral hypodermal chord; l.-m.ch , lateromedian hypodermal chord; m , somatic musculature; m.ch , median hypodermal chord; t , trophosome. Scale bar: 10 mm. Ovaries reflected. Egg diameter about 10.0 mm. Neither morphologically differentiated spermatheca nor spermatozoa nor vulvar glands observed. REMARKS B. filiformis was described on three specimens (two mature and one juvenile females) from the Norwegian Sea (64°- 73°N , 10°W- 10°E , depth 2615-2957 m ). The present new specimens were found in very distant regions, but they agree with the original description of B. filiformis in shape of the tail, construction of the gonad and the trophosome, in the body length and “V” index ( 3700-4700 mm and 46.8-56.8% respectively in the original description). But the new nematodes do not correspond with the original description for “a” and “c” (38.6-53.3 and 36.2-53.9 respectively vs 46.3-58.8 and 49.5-74.0 respectively). Besides, the distance from the anterior end to the amphids varies, and is less then in original description (42-121 vs 100-110 µm). The body length is greater than in the original description in most new specimens (4000-5516 vs 3700- 4700 µm). It seems to the author, in spite of these distinctions, that establishment of a new species is not rational, because there are no gaps between ranges of character measurements of new and earlier described specimens. Benthimermis hureaui Petter, 1983 ( Fig. 4 ; Tables 3 ; 4 ) Benthimermis hureaui Petter, 1983a: 7 , 8, fig. 4. FIG. 4. — Benthimermis hureaui Petter, 1983 , (see Tables 3 and 4 for locations and measurements of specimens); A , total view of specimen No. 2; B , cephalic end of specimen No. 2; C , cephalic end of specimen No. 1; D , reproductive system of specimen No. 2; E , tail of specimen No. 2; F , tail of specimen No. 1; G , region of the vulva of specimen No. 1. Abbreviations: a , amphid; h.c , hypodermal cells; l.ch , lateral hypodermal chord; m , somatic musculature; ov , ovary; ph , vestigial pharynx; t , trophosome; v.g , vulvar glands. Scale bars: A, 500 µm; B-G, 50 µm. TYPE MATERIAL .— Holotype : S Indian Ocean , 46°02.0’S , 49°08.5’E , 980 m , 28.IV.1976 , ( MNHN 153 BB ); paratypes : same locality, 5 ( MNHN 154 BB ). MATERIAL EXAMINED. — 2 immature (see Tables 3 and 4 for details). DESCRIPTION Measurements are presented in Table 4 . Body cylindrical, slightly narrower at anterior and posterior ends. Posterior end in shape of a truncated cone. Amphids non-spiral. Amphidial apertures pore-like, about 2 µm in diameter. Four mediolateral papilloid cephalic setae 3-4 µm long inserted in tiny pits. Pharynx looking like a non-muscular string devoid of an internal lumen. Specimen No. 2 possessing slight channel in cuticle instead of mouth, as well as vestigial rectum and anus. Cuticle of this specimen thicker at cephalic apex; borders between trophosomal cells distinct. Borders between trophosomal cells of specimen No. 1 indistinct, rectum and anus absent. Cuticle gradually thickened from 2-3 µm at anterior part of body to 4-5 µm at posterior part. Female reproductive system didelphic, amphidelphic, occupying about one quarter of total body length. Ovaries reflected. Neither morphologically differentiated spermatheca nor spermatozoa nor vulvar glands discovered. REMARKS B. hureaui was originally described from six specimens collected in the more western French Southern and Antarctic Islands (southern part of the Indian Ocean, 46°2’S , 49°8.5’E , 980 m depth). The new specimens were found in other regions remote from one another. Nevertheless, there is an evident close similarity between them and type specimens, except an absence of sclerotic ring around the vagina, which is mentioned in the original description. Besides, there are no rectum and anus in one specimen , whereas all specimens described by Petter (1983a) possess it. However, basing on these distinctions, an establishment of a new species is not rational.