Procamallanus (Spirocamallanus) dispar 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 : 2-5

Procamallanus (Spirocamallanus) dispar n. sp.

Figures 1 , 2

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Type host: Common ponyfish Leiognathus equulus (Forsskål) ( Leiognathidae , Perciformes ).

Other host: Striped ponyfish Aurigequula fasciata (Lacepède) ( Leiognathidae , Perciformes ).

Site of infection: Intestine.

Type locality: Fishmarket , Nouméa, New Caledonia (collected 1 October 2008) .

Prevalence, intensity and details about fish: L. equulus : 3 fish infected/4 fish examined; 2 nematodes per fish (Fish numbers: JNC 2644, JNC 2645, JNC 2647, 1 October 2008). A. fasciata : 1 fish infected/4 fish examined; 1 nematode (Fish number: JNC 2923, 29 April 2009). The infected fish were 129–137 mm in fork length and 62–68 g in weight ( L. equulus ), and 132 mm in length and 63 g in weight ( A. fasciata ).

Deposition of type specimens: Muséum National d’ Histoire Naturelle, Paris, France (male holotype, female allotype and 1 paratype, MNHN JNC 2644 and JNC2647 ); Helminthological Collection, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic (four male paratypes [three mounted on SEM stub], N–1200) .

Etymology: The specific name of this nematode dispar (= different) is the Latin adjective relating to the fact that this species differs from related congeners.

Description

General: Medium-sized nematodes 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 external circle distinctly larger; all papillae accompanied by distinct proximal pore; additional pair of pores situated laterally near edge of oral aperture; pair of small lateral amphids present ( Figs. 1D , 2A and 2B ). Buccal capsule orange, thick-walled, longer than wide, with simple, well-developed basal ring. Maximum width/length ratio of buccal capsule 1:1.12–1.39. Inner surface of capsule provided with 12–14 spiral ridges in lateral view, 4–6 of them being incomplete ( Figs. 1B and 1C ). Muscular oesophagus shorter than glandular oesophagus; both parts of oesophagus slightly expanded near their posterior ends ( Figs. 1A and 1B ). Intestine brown, narrow. Deirids small, simple, with rounded end situated approximately at mid-way between base of buccal capsule and nerve ring ( Figs. 1A, 1B, 1E and 2D ). Excretory pore located short distance anterior to posterior end of muscular oesophagus ( Fig. 1B ).

Male (four specimens, including holotype, from L. equulus ; measurements of one juvenile specimen from L. equulus in parentheses. Measurements of one specimen from A. fasciata in brackets): Length of body 17.95–20.13 (10.47) [16.32] mm, maximum width 258–326 (218) [272]. Buccal capsule including basal ring 81–90 (84) [87] long, its width 66–75 (69) [72]; basal ring 9–12 (9) [ 9] long and 48–54 (45) [54] wide. Maximum width/length ratio of buccal capsule 1:1.12– 1.36 (1:1.22) [1:1.21]. Spiral ridges 12–14 (16) [ 14], 6 (5) [ 5] of which incomplete. Length of muscular oesophagus 462– 503 (435) [490], maximum width 69–87 (69) [87]; length of glandular oesophagus 734–884 (503) [653], maximum width 108–126 (84) [126]; length ratio of muscular and glandular oesophagus 1:1.59–1.85 (1:1.16) [1:1.33]. Length of entire oesophagus and buccal capsule representing 6–7 (10) [ 8]% of body length. Deirids, nerve ring and excretory pore 279–357 (297) [309], 358–326 (272) [299] and 394–462 (490) [–] from anterior extremity, respectively. 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. 1F, 1H–1J , 2C and 2E–2H ). 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 transversely-elongate sessile ventral papillae surrounding cloacal opening ( Figs. 1F, 1H, 1J , 2E and 2G ). Spicules unequal, with sharply pointed distal ends; large (right) spicule 426–449 (195) [408] long; small (left) spicule less sclerotized, 180–250 (90) [204] long. Length ratio of spicules 1:1.70–2.42 (1:2.17) [1:2.00]. Gubernaculum absent. Tail conical, 135–195 (138) [135] long, with two (dorsal and ventral) small terminal cuticular spines 3–6 (6) [ 6] long ( Figs. 1F, 1H, 1I , 2G and 2H ).

Female (one ovigerous specimen from L. equulus , allotype): Length of body 19.07 mm, maximum width 313. Buccal capsule including basal ring 96 long and 69 wide; basal ring 9 long and 57 wide. Maximum width/length ratio of buccal capsule 1:1.39. Number of spiral ridges 12, of which 4 incomplete. Length of muscular oesophagus 462, maximum width 87; length of glandular oesophagus 558, maximum width 114; length ratio of muscular and glandular oesophagus 1:1.21. Length of entire oesophagus and buccal capsule representing 6% of body length. Deirids, nerve ring and excretory pore 345, 272 and 452, respectively, from anterior extremity. Vulva postequatorial, 9.86 mm from anterior extremity, at 52% of body length. Vulval lips not elevated. Uterus filled with numerous eggs. Tail broad, rounded, its posterior end abruptly narrowed to form terminal digit-like protrusion with smooth, rounded tip; length of entire tail 162; digit-like protrusion 36 long, 18 wide ( Fig. 1G ).

Remarks

The present specimens from L. equulus and A. fasciata are considered to be conspecific because of their morphological and biometrical similarity and the fact that both of their host species belong to the same fish family. These nematodes belong to the subgenus Spirocamallanus of the genus Procamallanus in the conception of Moravec and Thatcher [ 32], namely to the group of Spirocamallanus species characterized by the presence of wide caudal alae, three pairs of pedunculate preanal papillae and two unequal spicules, that are mostly parasites of marine fishes [ 37]. Most species of this group are characterized by the presence of two caudal spikes, one dorsal and one ventral, on a digital projection in the female [ 9, 46], whereas these are lacking only in a few species. According to Petter et al. [ 38], Rigby and Adamson [ 39] and Moravec et al. [ 27], the shape and structure of the female tail appears to be constant within a species of Procamallanus (Spirocamallanus) .

By the shape of the female tail and the absence of any terminal spikes, P. (S.) dispar n. sp. resembles only P. (S.) mexicanus Moravec, Salgado-Maldonado et Caspeta-Mandujano, 2000 from the freshwater cichlid Cichlasoma geddesi (Regan) ( Cichlidae ) in Mexico [ 29], P. (S.) murrayensis Johnston et Mawson, 1940 from freshwater perciform fishes Pseudaphritis urvillii (Valenciennes) (Pseudophritidae), Macquaria colonorum (Günther) and M. ambigua (Richardson) (both Percichthyidae ) in Australia [ 11] and P. (S.) sinespinis from the marine fish Pomadasys argenteus (Forsskål) ( Haemulidae ) off New Caledonia [ 26]. Vicente and Santos [ 45] did not report the presence of two terminal caudal spines in females of the inadequately described P. (S.) macaensis Vicente et Santos, 1972 , a parasite of several species of marine fishes in Brazil [ 16], but these are present according to the later redescription of this species [ 42].

However, in contrast to the new species, the right spicule of P. murrayensis is distinctly shorter (290 µm vs 408–449 µm). The right spicules of P. mexicanus and P. sinespinis are only slightly longer (456–480 µm and 465–525 µm, respectively vs 408–449 µm) than those of P. dispar , but the number of spiral ridges in their buccal capsules is 10–12 (vs 12–14); in addition, the male tail tip of these two species bears either a single conical cuticular spike ( P. mexicanus ) or a knob-like structure ( P. sinespinis ) (vs two, dorsal and ventral, terminal spikes are present); the female tail of P. mexicanus has a different shape, its anterior portion being narrow and conical (vs broad and posteriorly rounded). Moreover, P. mexicanus and P. murrayensis are parasites of freshwater fishes, whereas the hosts of P. dispar are marine fishes.

Moravec et al. [ 27] reported a nematode subgravid female, designated as Procamallanus (Spirocamallanus) sp. 3, from the marine fish Scolopsis bilineata (Bloch) ( Nemipteridae ) from off New Caledonia. The shape of its tail is similar to that of P. dispar and also the number (13) of spiral ridges in the buccal capsule corresponds to this species. However, the location of deirids is different (at the level of the nerve ring vs at the mid-way between the buccal capsule and the nerve ring), so that this specimen probably represents another species.

Figures

Figure 1. Procamallanus (Spirocamallanus) dispar n. sp. from Leiognathus equulus. (A) Anterior end of male, lateral view; (B) same, enlarged; (C, D) cephalic end of male, lateral and apical views, respectively; (E) deirid; (F) tail of male, ventral view; (G) tail of subgravid female, lateral view; (H) posterior end of male, lateral view; (I) tail tip of juvenile male, lateral view; (J) posterior end of juvenile male, ventral view.

Figure 2. Procamallanus (Spirocamallanus) dispar n. sp., scanning electron micrographs of male. (A, B) Cephalic end, lateral and apical views, respectively; (C) posterior end of juvenile specimen, lateral view (arrows indicate subventral preanal papillae); (D) deirid; (E) tail, ventrolateral view (arrows indicate elongate papillae surrounding cloaca); (F) posterior end, ventral view; (G) tail of juvenile specimen, ventral view; (H) distal part of tail, lateral view. (a) amphid; (b) cephalic papilla of external circle; (c) cephalic papilla of middle circle; (d) cephalic papilla of internal circle; (e) cloacal aperture; (f) lateral postanal papilla; (g) phasmid; (s) spicule.