Trefusia piperata, Leduc, 2013

Leduc, Daniel, 2013, Two new free-living nematode species (Trefusiina: Trefusiidae) from the Chatham Rise crest, Southwest Pacific Ocean, European Journal of Taxonomy 55, pp. 1-13 : 3-7

Trefusia piperata sp. nov.

Figs 1-2 , Table 1

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Diagnosis and relationships

Trefusia piperata sp. nov. is characterised by six double-jointed outer labial setae with conspicuous clusters of dark granules at their base, four cephalic setae at level of amphid, one seta posterior to each amphid, and long filiform tail. Male is characterised by six cervical papillae, eight papillose pre-cloacal supplements, slightly bent spicules, and gubernaculum with funnel-shaped distal portion and pointed projections.

Trefusia piperata sp. nov. most closely resembles T. helgolandica Riemann, 1966 , described from subtidal sediments in the German Bight. The two species are similar in the shape and position of the outer labial setae and cephalic setae, as well as in the structure of the spicules and gubernaculum. The new species, however, differs from T. helgolandica in head diameter (14-15 vs. 22-25), maximum body width (21-22 vs. ≥ 33), spicule length (24 vs. 38), number of setae posterior to the amphids (one vs. two or three), the number and shape of cervical papillae (six papillae with wide base vs. thirteen papillae without wide base), and number of pre-cloacal supplements (eight vs. fourteen). Trefusia piperata sp. nov. also differs from T. helgolandica in the presence of conspicuous clusters of dark granules at the base of the outer labial setae.

Etymology

The species name is derived from the latin word piperatus (= peppered), and refers to the conspicuous clusters of dark granules at the base of the cephalic setae.

Material examined

Holotype

♂, collected on 20 Feb. 2011 (NIWA cruise TAN1103, station 69), central Chatham Rise (43.331° S, 178.288° E), water depth 350 m, sediment depth 1-5 cm, mean grain size 55-59 µm, %sand 55-57%, particle sorting (geometric) 4.1-4.3 ( NIWA 88347 ).

Paratype

1 ♀, same data as holotype ( NIWA 88348).

Description

Male

Body cylindrical, slender, tapering slightly towards anterior extremity ( Fig. 2C ). Cuticle thin, <1 µm thick, with very fine striations, difficult to observe. Head blunt, slightly rounded, with three lips; six small conical inner labial sensillae, ~ 1 µm long, six double-jointed outer labial setae with blunt ends, ca. 0.7 cbd ( Fig. 1B ). Conspicuous clusters of dark brown granules situated at base of each outer labial seta ( Fig. 2A ). Four cephalic setae at level of amphid, jointed, 5-7 µm long ( Fig. 1B ). Amphid pocket-shaped with oval aperture, ca. 4 µm wide by 2 µm high. One seta situated ca. 25 µm posterior to each amphid, 5 µm long. No other somatic setae observed. Six small cervical papillae with wide base situated ventrally in longitudinal row; row extends from posterior of amphid to about 60% of pharynx length from anterior ( Fig. 1B ). Buccal cavity funnel-shaped, without teeth. Pharynx cylindrical, slightly swollen at anterior and posterior extremities, completely surrounds buccal cavity. Nerve ring situated at ca. 45% of pharynx length from anterior extremity. Secretory-excretory system not observed. Cardia very small.

*at level of cephalic setae

Reproductive system diorchic with outstretched testes. Position of testes relative to intestine difficult to ascertain. Sperm cells drop-shaped with rod-shaped nucleus; vas deferens ca. 445 µm long. Paired, equal spicules, slightly bent near distal one third, without obvious central cuticularised projection (i.e., lamella or median rib). Gubernaculum with narrow proximal region and funnel-shaped distal region with large anterior pointed projection and smaller posterior pointed projection ( Figs 1D , 2B ). Eight small papillose pre-cloacal supplements situated ventrally, 6-15 µm apart except for anterior-most supplement which is situated 40 µm from next supplement. Tail very long, ca. half of total body length, filiform, without setae, tightly coiled.

Female

Similar to male, but with slightly shorter cephalic setae and slightly smaller amphid ( Fig. 1A ). Female reproductive system didelphic, amphidelphic with reflexed ovaries. Position of ovaries relative to the intestine difficult to ascertain. Vulva situated at one third of body length ( Fig. 1C ).

Discussion

Trefusia piperata sp. nov. was rare at the study site, with only four specimens (the two type specimens and two juveniles in poor condition, each from a different subcore) recorded out of the 4412 individuals that were identified by Leduc & Pilditch (2013). Two individuals were found in the 1-3 cm sediment depth layers, and two were found in the 3-5 cm sediment depth layer (D. Leduc, unpublished data).

Figures

Fig. 1. Trefusia piperata sp. nov. A. Anterior body region of female. B. Anterior body region of male. C. Entire female. D. Right spicule and gubernaculum. E. Posterior body region of male. Arrow shows position of vulva. Scale bar: A-B, E = 20 µm; C = 75 µm; D = 8 µm.

Fig. 2. Trefusia piperata sp. nov. Light micrographs. A. Head region of male, showing buccal cavity, cephalic setae, and clusters of dark granules at base of outer labial setae. B. Spicule and gubernaculum. C. Entire male. Scale bar: A-B = 10 µm; C = 100 µm.

Tables

Table 1. Morphometrics (µm) of Trefusia piperata n. sp. and Trefusialaimus idrisi n. sp. (a: body length/ maximum body diameter, abd: anal body diameter, b: body length/pharynx length, c: body length/tail length, cbd: corresponding body diameter, V: vulva distance from anterior end of body, %V: V/total body length).

Species	Trefusia piperata sp. nov.		Trefusialaimus idrisi sp. nov.
	Holotype ♂	Paratype ♀	Holotype ♂	Paratype juv.
n		1		1
L	3663	4492	4539	2826
a	167	214	130	97
b	14	16	13	9
c	2	2	7	5
Head diameter*	14	15	20	17
Mouth diameter	4	3	1	2
Length of sub-cephalic setae	5-7	6-7	-	-
Length of cephalic setae	9	7-8	8-10	6
Amphid height	5	4	2	2
Amphid width	4	3	6	5
Amphid width/cbd (%)	29	20	30	29
Amphid from anterior end	17	19	38	33
Nerve ring from anterior end	119	117	177	152
Nerve ring cbd	22	20	31	27
Pharynx length	260	281	357	314
Pharyngeal bulb diameter	13	19	20	17
Pharyngeal bulb cbd	21	14	34	28
Max. body diameter	22	21	35	29
Spicule length	24	-	39	-
Gubernaculum length	9	-	14	-
Anal body diameter	21	15	17	17
Tail length	1806	2330	650	590
Tail length/abd	86	155	38	35
V	-	1383	-	-
%V	-	31	-	-
Vulval body diameter	-	21	-	-