Spirinia verecunda, Leduc & Verschelde, 2015

Leduc, Daniel & Verschelde, Dominick, 2015, New Spirinia and Stygodesmodora species (Nematoda, Spiriniinae) from the Southwest Pacific, and a revision of the related genera Spirinia, Chromaspirina and Perspiria, European Journal of Taxonomy 118, pp. 1-25 : 10-14

Spirinia verecunda sp. nov.

urn:lsid:zoobank.org:act:83F4CF38-29CF-4540-B05D-2245120A489B

Figs 1–3 ; Table 1

Diagnosis

Spirinia verecunda sp. nov. is characterised by a short, stout body, cuticle covered in minute hair-like structures, unispiral amphideal aperture and cryptospiral amphideal fovea, buccal cavity with a small dorsal tooth and minute subventral teeth, eight elongated glands surrounding the anterior portion of the pharynx, large sperm cells, spicules with weak capitulum, and absence of precloacal supplements.

Type material

Holotype

NEW ZEALAND: ♂, NIWA 88379 , 20 Feb. 2011, NIWA cruise TAN1103, station 69, central Chatham Rise , 43.331° S, 178.288° E, 350 m.

Paratypes

NEW ZEALAND: 2 ♀♀, NIWA 88380, same data as holotype.

Etymology

The species name is derived from the Latin word verecundus (bashful, shy, coy), in reference to the anterior part of the head region deeply folded inwards.

Description

Male

Body stout, cylindrical, pale orange colour, tapering slightly towards both ends. Annulated cuticle, no lateral differentiation; annulations 0.6–0.8 µm apart; cuticle slightly thicker in pharyngeal region than elsewhere (2.2–2.5 vs 1.6–2.0 µm). Cuticle covered with dense layer of minute hair-like structures from posterior to amphid to near tail tip (barely visible under light microscope; Fig. 3 A–B); larger, 1 × 5 µm bacteria-like structures with narrow base also attached in pharyngeal region ( Fig. 1D ). A single protist, 74 µm long and 18 µm wide attached subdorsally near cloaca ( Fig. 3E ). Short somatic setae arranged in eight longitudinal rows along entire body length.

Blunt, slightly rounded annulated head region with annulations completely surrounding amphid ( Fig. 1 A–B). Four cephalic setae near anterior edge of amphid; inner and outer labial sensillae not observed because labial region is folded inwards from level of cephalic setae. Cryptospiral amphideal fovea with slightly cuticularised outline and unispiral amphideal aperture ( Fig. 3 A–B).

Buccal cavity with slightly cuticularised dorsal tooth and minute subventral teeth. Eight elongated glands, 12–17 µm in length, distributed around anterior portion of pharynx just posterior to buccal cavity ( Figs 1 C–D, 3C). Pharynx muscular, oval-shaped posterior pharyngeal bulb, lumen not cuticularised. Nerve ring at 40–50% of pharynx length. Secretory-excretory system not observed. Cardia 10–12 µm long.

Reproductive system monorchic, with relatively large, outstretched testis situated to the left of intestine. Mature sperm large, globular to elongated in shape, up to 16 µm in length. Short, arcuate spicules with weak capitulum and tapering distally; velum present ( Fig. 1G ). Gubernaculum with cuneus broadest in middle portion and tapering proximally and distally; poorly developed lateral crurae ( Fig. 1H ). Precloacal supplements not observed. Tail conical, with two pairs of short subventral setae and one pair of subdorsal setae; three caudal glands restricted to tail region and spinneret present.

Female

Similar to male, but with wider body. One specimen bears a single protist (suctorian) on tail. Reproductive system didelphic, amphidelphic with reflected ovaries situated either both on the right or both on the left of intestine. Vulva located slightly post median. Cuticular pars distalis vaginae and pars proximalis vaginae surrounded by constrictor muscle.

Remarks

Spirinia verecunda sp. nov. shows similarities with several Spirinia and Chromaspirina species, i.e., Spirinia guanabarensis comb. nov., S. inaurita comb. nov., S. okemwai comb. nov., S. parma comb. nov., Chromaspirina chabaudi , and C. multipapillata . Of these, S. verecunda sp. nov. resembles S. okemwai comb. nov. the most in cuticle ornamentation (annulated head region, cuticle with minute hairlike structures), size and shape of the amphids, presence of large sperm cells, and absence of precloacal supplements. S. verecunda sp. nov. differs from the latter in having shorter body length (667–757 vs 966–1425 µm), lower values of a (17–22 vs 22–27), shorter cephalic setae (2 vs 3–6 µm), shorter spicules (38 vs 41–50), and shorter gubernaculum (13 vs 19–25). S. verecunda sp. nov. also differs from S. okemwai comb. nov. in the presence of elongated glands in the anterior region of the pharynx (absent in S. okemwai comb. nov.) and the structure of the gubernaculum (hook absent vs dorsally directed proximal hook). S. verecunda sp. nov. can most readily be distinguished from S. inaurita comb. nov. and S. parma comb. nov. by the size of the amphids (in males: 35% cbd in S. vercunda sp. nov. vs> 60% cbd in S. inaurita comb. nov. and S. parma comb. nov.), from Chromaspirina chabaudi by the structure of the gubernaculum (not surrounding spicules in S. verecunda sp. nov. vs surrounding spicules distally in C. chabaudi ), from C. multipapillata by the absence of precloacal supplements (present in C. multipapillata ), and from S. guanabarensis comb. nov. by its small body size (<800 µm in S. verecunda sp. nov. vs> 1800 µm in S. guanabarensis comb. nov.) and low values of a (17–22 vs 30–48).

Figures

Fig. 1. Spirinia verecunda sp. nov. A. Surface view of male head. B–C. Male head, showing buccal cavity. D. Female head, showing bacteria attached to cuticle. E. Anterior body region of male. F. Anterior body region of female. G. Posterior body region of male. H. Gubernaculum, with details of crurae (left) and cuneus (right). I. Posterior body region of female. J. Posterior body region of female, showing attached protist. Scale bar: A–D, I = 20 µm, E–F = 30 µm, G = 16 µm, H = 12 µm, J = 35 µm.

Fig. 2. Spirinia verecunda sp. nov. A. Entire male. B. Female reproductive system. Scale bar: A = 50 µm, B = 30 µm.

Fig. 3. Spirinia verecunda sp. nov., light micrographs. A. Male head, showing amphideal aperture and and cuticular hair-like structures. B. Male head, showing amphideal fovea. C. Male anterior body region showing buccal cavity and elongated glands. D. Mature sperm cells. E. Posterior body region of male, showing copulatory apparatus and attached protist. Scale bar: A–B, D–E = 10 µm, C = 8 µm.

Tables

Table 1. Morphometrics (µm) of Spirinia verecunda sp. nov. and Stygodesmodora confusa sp. nov. — 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.

	Spirinia verecunda sp. nov.		Stygodesmodora confusa sp. nov.
	♂	♀♀	♂♂		♀♀
	Holotype	Paratypes	Holotype	Paratype	Paratypes
n	-	2	-	1	5
L	757	667, 675	1241	795	778–1029
a	22	17	35	28	22–34
b	8	6,7	11	8	8–10
c	15	13	13	14	12–15
Head diameter	17	17, 18	18	14	14–16
Length of cephalic setae	2	2	7–8	6–9	5–9
Amphid height	6	6, 7	11	6	5–6
Amphid width	6	6, 7	11	6	6–7
Amphid width/cbd (%)	35	33, 41	61	43	40–47
Amphid from anterior end	2	3	4	5	3–7
Nerve ring from ant. end	49	45, 53	68	59	57–62
Nerve ring cbd	32	32, 33	29	25	24–25
Pharynx length	100	100, 107	109	95	92–105
Pharyngeal bulb diameter	26	27	22	20	20–22
Pharyngeal bulb cbd	31	33, 34	29	25	25–28
Max. body diameter	35	39, 40	35	42	30–37
Spicule length	38	-	39	42	-
Gubernaculum length	13	-	10	12	-
Anal body diameter	24	21, 22	28	21	17–20
Tail length	49	51, 52	93	57	62–85
Tail length/abd	2.0	2.4	3.3	2.7	3.5–4.5
V	-	347, 361	-	-	428–558
%V	-	51,54	-	-	53–55
Vulval body diameter	-	39, 40	-	-	30–37