Huffmanela balista, Justine, Jean-Lou, 2007

Justine, Jean-Lou, 2007, Huffmanela spp. (Nematoda, Trichosomoididae) parasites in coral reef fishes off New Caledonia, with descriptions of H. balista n. sp. and H. longa n. sp., Zootaxa 1628, pp. 23-41 : 27-31

Huffmanela balista n. sp.

( Figs 1–3 )

Type-host: Abalistes stellatus Anonymous (ex Commerson) ( Balistidae ). Note that A. stellaris (Bloch & Schneider) is a junior synonym (Matsuura & Yoshino, 2004).

Host: single infected fish, JNC2163, 02.v.2007, near Récif Toombo, off Nouméa, New Caledonia, 22°32’S, 166°28’E, FL 430, W 1500.

Type-locality: Lagoon off Nouméa, New Caledonia.

Material examined: One complete male (holotype) and several fragments of immature males (paratypes); one incomplete immature female (allotype); laid eggs.

Deposition of specimens: Holotype, allotype and paratypes, MNHN, JNC 2163; vouchers of eggs, MNHN, JNC 2163; HCIP, N-880; BMNH, 2007.7.12.1; USNPC, 99977; SAMA, AHC 34775.

Site of infection: external mucosa of swimbladder.

Etymology: Latinization of French baliste, common name for the host; used as a name in apposition.

Male [mainly from holotype, the single complete specimen]. Body length, holotype 9870, maximum width 30; width of cephalic end 10, of posterior end 17. Two lateral bacillary bands 8–10 wide. Length of entire oesophagus 3890 (39% of body length), length of muscular oesophagus 366, length of posterior part 5980 (in a paratype 4775). Nerve ring not seen. Length of stichosome 3524; stichocytes approximately 25 in number; length of stichocytes 80–130 in middle region of stichosome; terminal stichocyte 160 in length. Single testis reaching anteriorly nearly to oesophago-intestinal junction. Testis hologonic, spermatids and spermatozoa interspersed; spermatids, oval, 23 × 11, with oblong nucleus; spermatozoa, 21 × 6, more elongate with dense body within cytoplasm, in two parallel lines. Spicule and spicular sheath absent. Caudal end slightly narrowed, rounded; no papillae seen.

Female [from allotype, single female specimen, probably immature, tail lacking]. Body length (incomplete) 4850, maximum width 56, width of cephalic end 16. Length of entire oesophagus 1980, of muscular oesophagus 438, of posterior part (broken) 2870. Muscular oesophagus with anterior cuticularised part, 203 in length with very regular diameter 8–9, and posterior part, not cuticularised, 235 in length. Region of vulva damaged, not illustrated; no vulvar appendage. Immature eggs in uterus, oblong, embryonated with several cells visible, without shell but with regular hyaline peripheral layer, 41–44 × 17–21.

L 1 larvae. Spontaneously hatched larvae, length 260 (245–295, n = 4), maximum width 6.5.

Eggs in tissue. Mature eggs yellow-brown to dark-brown. Eggs elongate, with protruding plugs. Size of eggs including polar plug 70.5 ± 2.9 (63–78) × 34.5 ± 1.5 (32–41) (n = 132); egg wall 5–6. Eggs prepared using various methods, see Table 2 . Fully developed larvae in most eggs, body width 6–8. Superficial envelope of eggs often inconspicuous; when visible, envelope thin and unornamented; no filaments. Surface of eggs ornamented with inconspicuous longitudinal ridges.

Eggs formed thick dark layer within external mucosa of swimbladder ( Figure 1 ). Fibrous mucosa easily removed from rest of swimbladder; no eggs visible in deeper layer of swimbladder wall nor on internal surface of the organ. No other organ infected.

Eggs kept in seawater (ethanol-preserved ‘24h eggs’) showed length measurements ( Table 2 ) different from ‘ethanol-preserved eggs’ (74.7 vs 71.3, difference 3.6 µm, highly statistically different) width not different (34.8 vs 34.9). Difference due to plugs which protruded at each extremity, in contrast to fresh eggs in which plugs were very flat (all length measurements include the plugs). In many ‘24h eggs’, larvae emerging from eggs were observed. Egg shell does not change when eggs mature, but plugs are modified.

Mobility of larvae and hatching. Larvae feebly motile in laid eggs. Hatching occurred in many eggs after 24h at room and refrigerator temperatures; hatched larvae were mobile.

Differential diagnosis of adults. The male is characterised by its oesophagus length (3.9 mm) and its total length (9.8 mm), both of which longer than all other known species (1.4–1.9 and 4.7–5.1 in H. huffmani , 1.3 and 3.4–3.9 in H. canadensis and 1.5–1.6 and 3.8–6.4 in H. moraveci ). Its maximum width (30 µm) is similar to that of H. huffmani (24–27) but smaller than that of H. canadensis (45–63) and H. moraveci (60– 90).

The female is characterised by its cuticularised oesophagus; no similar structure has been described in other species. The measurement of total oesophagus length is within the range of the three other species, but since the specimen was immature it is possible that mature females are longer than in the three other known species.

Differential diagnosis of eggs. Moravec (2001) proposed a key to the species of Huffmanela with two major categories, species with long (>90 µm) eggs and species with shorter eggs. H. balista falls into the latter category.

Three species have egg measurements comparable to that of H. balista ( Table 1): these are H. mexicana , H. schouteni and H. longa .

H. mexicana has eggs 63–69 × 30–33 in the original publication, but measurements taken with the same microscope and methods as for H. balista shows that the eggs of H. balista are longer (66 × 29 vs 57 × 30). In addition, the eggs of H. mexicana have a few superficial filaments ( Figure 6 ), not seen in H. balista .

H. schouteni has eggs of similar size (69–75 vs 27–30) but the eggs have superficial protuberances, compared with longitudinal inconspicuous ridges in H. balista .

It is noteworthy that both these species have been reported from the same organ, the swimbladder, as H. balista . However, in both species ( Moravec & Fajer-Avila 2000; Moravec & Garibaldi 2004), as well as in H. huffmani ( Moravec 2001) the site was the inner layer of the swimbladder, compared with the outer layer in the case of H. balista .

The comparison with H. longa is considered under the differential diagnosis of that species.

Figures

FIGURE 1. Outer surface of the swimbladder of Abalistes stellatus (fish JNC 2163). Dark zones are accumulations of eggs of Huffmanela balista n. sp.

FIGURE 6. A. Egg of Huffmanela mexicana Moravec et Fajer-Avila, 2000, for comparison with other species. B – D. Hatching eggs and larvae of Huffmanela ossicol a Justine, 2004 from the gills of Bodianus perditio.

Tables

TABLE 2. Egg measurements of Huffmanela balista, JNC 2163, from swimbladder.

Methods and characteristics of eggs	Length	Width	n
Dark brown ‘fresh eggs’	70.5 ± 2.9 (63–78)	34.5 ± 1.5 (32–41)	132
Dark brown ‘ethanol-preserved eggs’	71.3 ± 3.2 (64–78)	34.8 ± 1.6 (31–39)	86
Dark brown ‘formalin-preserved eggs’	71.4 ± 2.3 (66–77)	33.7 ± 1.2 (32–37)	76
Yellow ‘fresh eggs’	71.2 ± 4.2 (63–81)	35.0 ± 1.7 (30–39)	48
Dark brown ‘ethanol-preserved 24h eggs’	74.7 ± 2.2 (71–80)	34.9 ± 1.4 (32–38)	79