Procamallanus (Spirocamallanus) thalassomatis n. sp., 2019

Moravec, František & Justine, Jean-Lou, 2019, New species and new records of camallanid nematodes (Nematoda, Camallanidae) from marine fishes and sea snakes in New Caledonia, Parasite (Paris, France) 26 (66), pp. 1-25 : 15-18

Procamallanus (Spirocamallanus) thalassomatis n. sp.

Figures 9–11

urn:lsid:zoobank.org:act:1B89617C-7328-471A-9A60B25190D68E0E

Type host: Yellow-brown wrasse Thalassoma lutescens (Lay et Bennett) ( Labridae , Perciformes ).

Site of infection: Intestine.

Type locality: Reef near Passe de Dumbéa, New Caledonia, 22°21 0 189 S, 166°15 0 158 E (collected 16 October 2009).

Prevalence, intensity and details about fish: 1 fish infected/8 fish examined; 3 nematodes. The infected fish (Fish number: JNC 3074) was 173 mm in fork length and 63 g in weight.

Deposition of type specimens: Helminthological Collection , Institute of Parasitology , Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic (male holotype and female allotype, both mounted on SEM stub, N–1204); Muséum National d’ Histoire Naturelle, Paris, France (female paratype, MNHN JNC 3074 ) .

Etymology: The specific name of this nematode relates to the genitive form of the generic name of the host.

Description

General: Medium-sized nematode with finely transversely striated cuticle. Mouth aperture oval, surrounded by 12 submedian cephalic papillae arranged in three circles, each formed by four papillae; papillae of outer circle larger; each of four small inner papillae present near margin of oral aperture accompanied by distinct proximal pore; pair of small lateral amphids present ( Figs. 9D , 10A, 10B and 10C ). Buccal capsule orange, thick-walled, longer than wide, with simple, well-developed basal ring. Maximum width/length ratio of buccal capsule 1:1.07–1.21. Inner surface of capsule provided with 11–12 spiral ridges in lateral view, 4–5 of them being incomplete ( Figs. 9B, 9C and 10C ). Muscular oesophagus shorter than glandular oesophagus; both parts of oesophagus slightly expanded near their posterior ends ( Fig. 9A ). Intestine brown, narrow. Deirids small, simple, with rounded end situated slightly anterior to level of nerve ring ( Figs. 9B, 9G and 10D ). Excretory pore located somewhat posterior to anterior end of glandular oesophagus ( Fig. 9A ).

Male (one specimen, holotype): Length of body 12.53 mm, maximum width 313. Buccal capsule including basal ring 87 long, its width 72; basal ring 12 long and 57 wide. Maximum width/length ratio of buccal capsule 1:1.21. Spiral ridges 12, 5 of which incomplete. Length of muscular oesophagus 435, maximum width 93; length of glandular oesophagus 748, maximum width 126; length ratio of muscular and glandular oesophagus 1:1.72. Length of entire oesophagus and buccal capsule representing 10% of body length. Deirids, nerve ring and excretory pore 279, 299 and 558, respectively, from anterior extremity. Posterior end of body ventrally bent, provided with wide, vesiculated caudal alae supported by pedunculate papillae; anteriorly alae interconnected by mound, forming a kind of pseudosucker, and posteriorly reaching to caudal terminal spines ( Figs. 9E, 9F , 11A, 11B, 11C and 11D ). Preanal papillae: three pairs of subventral pedunculate papillae, of which second and third pairs closer to each other than first and second pairs; postanal papillae: six pairs of pedunculate papillae, four subventral and two lateral (last pair representing phasmids); additional two pairs of small, transversely-elongate sessile ventral papillae surrounding cloacal opening ( Figs. 9E, 9F , 10E , 11A, 11B and 11D ). Spicules unequal, with sharply pointed distal ends ( Fig. 9F ); large (right) spicule 330 long; small (left) spicule less sclerotized, 144 long. Length ratio of spicules 1:1.48 (1:2.29). Gubernaculum absent. Tail conical, 141 long, with two (dorsal and ventral) small terminal cuticular spines four long ( Figs. 9F and 11A ).

Female (two larvigerous specimens; allotype; measurements of paratype in parentheses): Length of body 25.55 (25.66) mm, maximum width 639 (598). Buccal capsule including basal ring 96 (99) long and 90 (90) wide; basal ring 12 (12) long and 63 (63) wide. Maximum width/length ratio of buccal capsule 1:1.07 (1:1.10). Number of spiral ridges 11 (12), of which 4 (5) incomplete. Length of muscular oesophagus 625 (666), maximum width 136 (122); length of glandular oesophagus 1088 (1170), maximum width 177 (177); length ratio of muscular and glandular oesophagus 1:1.74 (1:1.76). Length of entire oesophagus and buccal capsule representing 7 (8)% of body length. Deirids, nerve ring and excretory pore 313 (326), 381 (367) and 762 (768), respectively, from anterior extremity. Vulva slightly pre-equatorial (equatorial), 12.65 (12.92) mm from anterior extremity, at 49 (50)% of body length. Vulval lips not elevated ( Fig. 9I ). Vagina directed posteriorly from vulva. Uterus filled with numerous larvae 381–396 long, with slender tail. Female tail broad, rounded, its posterior end abruptly narrowed to form digit-like protrusion provided with 2 (2), dorsal and ventral, small terminal cuticular spikes; length of entire tail 195 (201); digit-like protrusion 30 (42) long, 15 (15) wide, length of spines 3 (3) ( Figs. 9H, 9J , 10F and 10G ).

Remarks

The nematodes from T. lutescens belong to the same morphological group of Procamallanus (Spirocamallanus) as the species P. bothi n. sp., P. hexophtalmatis n. sp. and P. synodi n. sp. (see above). From the Indo-Pacific species of this group, P. pereirai and P. similis can be differentiated from P. thalassomatis n. sp. by possessing a distinctly longer right spicule (430 µm and 435–492 µm, respectively vs 330 µm) and P. bothi in having a shorter right spicule (267–270 µm), whereas the length of this spicule in the remaining species ( P. anguillae , P. gobiomori , P. guttatusi , P. istioblenni , P. monotaxis , P. rigbyi and P. variolae ) is rather similar. However, in having deirids located near the level of the nerve ring, they resemble only P. hexophtalmatis , P. synodi and P. variolae , whereas deirids in other species are situated approximately in the mid-way between the buccal capsule and the nerve ring (in P. istiblenni in 2/3 of this distance).

On the basis of the location of deirids somewhat anterior to the level of the nerve ring, P. thalassomatis n. sp. resembles P. hexophtalmatis n. sp., whereas deirids in P. variolae and P. synodi n. sp. are located at the level of the nerve ring or just posterior to this level. However, P. thalassomatis differs from P. hexophtalmatis in the vagina directed anteriorly (vs posteriorly) from the vulva; although the male body of the former species is shorter than that of the latter species (12.5 mm vs 15.5 mm), its buccal capsule is distinctly larger (87 × 72 µm vs 75–84 × 60 µm). The new species can be differentiated from P. variolae mainly by the length ratio of the muscular and glandular parts of the oesophagus (1:1.7–1.8 vs 1:1.1–1.3) and by the percentage of the length of the oesophagus and buccal capsule of the entire body length of gravid females (7–8% vs 5%), whereas from P. synodi mainly by the shape of the female tail (broadly rounded vs conical) and the larger buccal capsule (87 × 72 µm in male and 96–99 × 90 µm in gravid female vs 66–81 × 60–66 µm in male and 66–75 × 66–72 µm in subgravid female). Moreover, the hosts of P. hexophtalmatis , P. synodi and P. variolae belong to other fish families than that of the new species ( Pinguipedidae , Synodontidae and Serranidae , respectively vs Labridae ).

Procamallanus (S.) thalassomatis n. sp. is the first species of this genus reported from a fish of the family Labridae .

Figures

Figure 9. Procamallanus (Spirocamallanus) thalassomatis n. sp. from Thalassoma lutescens. (A, B) Anterior end of male, lateral and dorsoventral views, respectively; (C) buccal capsule of male, lateral view; (D) cephalic end, apical view; (E) tail of male, ventral view; (F) posterior end of male, lateral view; (G) deirid; (H) tail of female, lateral view; (I) vulva and distal end of vagina, lateral view; (J) tail tip of female, lateral view.

Figure 10. Procamallanus (Spirocamallanus) thalassomatis n. sp., scanning electron micrographs. (A, B) Cephalic end, sublateral and apical views, respectively (arrows indicate circumoral pores); (C) region of oral aperture, subapical view (arrows indicate circumoral pores); (D) deirid; (E) region of cloaca, sublateral view (arrows indicate pores of flat papillae around cloaca); (F) tail of gravid female, ventral view; (G) caudal projection of gravid female, sublateral view. (a) amphid; (b) cephalic papilla of external circle; (c) cephalic papilla of middle circle; (d) cephalic papilla of internal circle; (i) anus; (s) spicule.

Figure 11. Procamallanus (Spirocamallanus) thalassomatis n. sp., scanning electron micrographs of male. (A) Posterior end of body, lateral view; (B) tail, lateral view; (C) posterior end of body, ventral view; (D) tail, ventral view. (d) caudal ala; (e) cloaca; (s) spicule.