Gyrodactylus jarocho, Rubio-Godoy, Miguel, Paladini, Giuseppe & García-Vásquez, Adriana, 2010

Rubio-Godoy, Miguel, Paladini, Giuseppe & García-Vásquez, Adriana, 2010, Gyrodactylus jarocho sp. nov. and Gyrodactylus xalapensis sp. nov. (Platyhelminthes: Monogenea) from Mexican poeciliids (Teleostei: Cyprinodontiformes), with comments on the known gyrodactylid fauna infecting poeciliid fish, Zootaxa 2509, pp. 1-29 : 7-11

Gyrodactylus jarocho sp. nov.

( Figures 1 , 32–38 ; Table 3 )

Type host: Xiphophorus hellerii Heckel (“green swordtail”, “cola de espada verde”). Site of infection: Fins.

Type locality: Río Mondongo, Los Naranjos, Veracruz, México (18°21'39''N, 96°10'32''W).

Type material: Four specimens were studied for light microscopy. Holotype and a paratype are deposited in the Parasitic Worm collection at The Natural History Museum ( BMNH reg. nos. 2010.3.11.8 and 2010.3.11.9, respectively), London, UK. In addition, two paratypes are lodged in the Colección Nacional de Helmintos ( CNHE reg. no. 7130), Instituto de Biología, Universidad Nacional Autónoma de México, México City.

Etymology: Named after the demonym or gentilic for the people of Veracruz, which is “ jarocho ”.

Description: Body and haptor measured on a single specimen; haptoral armature measured on all four specimens. Body elongate, 323 long; 78 wide at the level of the uterus. Haptor longitudinally-ovate, clearly delineated from the body, 85 long × 60 wide. Male copulatory organ (MCO), observed on a single specimen, 11.0 long × 8.7 wide, spherical, armed with one large spine and a single ring of 8 spines arranged in the following configuration: 2 small, 1 medium, 2 small, 1 medium, 2 small. Medium sized MCO spines 2.3 long, small spines 1.6 long ( Figure 38 ). Hamulus total length 67.1 (66.3–68.6); shaft length 44.0 (43.6–44.6); point 26.6 (25.9–27.1) long with a 46.8° (46.2–47.7°) aperture; root 25.6 (24.9–26.3) long, tapering, root ends slightly outwardly turned ( Figures 32, 36 ). The regions of ventral bar articulation on the hamuli are narrow, approximately oblong. Dorsal bar 28.6 (27.9–29.8) long marked by a 0.7 (0.6–0.9) rectangular notch at its centre. The dorsal bar thickens from the centre towards the hamuli but narrows immediately before its attachment ( Figures 32, 36 ). Dorsal bar attachment points small, anterior edge of which makes a right angle union with the hamulus. Ventral bar 32.3 (29.3–37.7) long; 29.2 (27.9–30.6) wide; ventral bar processes prominent, 9.1 (8.5–9.9) long and attach on the tangential, lateral face of the median portion of the ventral bar proper. Central region of the median ventral bar proper angled slightly towards its centre; lateral extremities are wider, posterior edge stepped, extending around the posterior edge of the central region of the median ventral bar proper. Ventral bar membrane lingulate, posterior edge rounded, 14.7 (11.7–21.7) long. Lateral margins of the membrane not thickened; the median region of the membrane striated (= points of muscle insertion) ( Figures 32, 36 ). Marginal hook 28.8 (27.9–30.3) long; shaft length 22.7 (21.7–24.3); sickle proper length 6.5 (6.4–6.6); sickle base triangular; heel rounded; toe: heel ratio 1:1 (underside of sickle base). Sickle proximal width 4.7. Sickle shaft narrow, slightly forward sloping; sickle point terminates approximately parallel to the base of the sickle and in line with the toe. Distal width 3.5 (3.2–4.0); sickle aperture 6.1 (5.9– 6.5) long. Toe triangular, 2.0 (1.9–2.2) long; toe bridge short and forward sloping ( Figures 33–35, 37 ).

Comments: Gyrodactylus jarocho sp. nov. is the third gyrodactylid described from X. hellerii . Previously, Gyrodactylus rasini Lucký, 1973 was collected from aquarium hosts ( Lucký 1973), and Gyrodactylus turnbulli Harris, 1986 from X. hellerii × X. maculatus Günther hybrids ( Harris 1986) and from feral X. hellerii in Australia ( Dove & Ernst 1998). It would be interesting to determine whether G. j a ro c h o sp. nov. also occurs on aquarium and feral populations of this poeciliid, outside its native distribution range in México, Belize, Guatemala and Honduras ( Froese & Pauly 2009).

Of the known species of Gyrodactylus described from poeciliids, the marginal hook sickles of G. j a ro c h o sp. nov. are most morphologically similar to those of G. bullatarudis . Both species possess sickles with approximate triangular shaped bases and large heels. Differences in the shaft and point regions of the sickle, however, permit their discrimination from one another. The shaft of G. bullatarudis is broad when compared to that of G. j a ro c h o sp. nov. ( Figure 4 ); the shaft is uniform along its length and then abruptly turns to end in a short tip. The shaft of G. jarocho sp. nov., however, curves gently and tapers towards its tip, which is considerably longer than that of G. bullatarudis .

The discrimination of G. j a ro c h o sp. nov. from each of the other known gyrodactylid species infecting poeciliid fish is based on marginal hook sickle morphology and is commented upon under each species rather than here.

Figures

FIGURES 1 – 14. A size invariant comparison of the marginal hook sickles of two new species of Gyrodactylus with the nine species previously recorded infecting poeciliids. 1. Gyrodactylus jarocho sp. nov.; 2. Gyrodactylus xalapensis sp. nov.; 3. Gyrodactylus bullatarudis Turnbull, 1956 (re-examination); 4. Overlay of G. bullatarudis with G. j a ro c h o sp. nov. (broken line); 5. Overlay of G. bullatarudis with G. xalapensis sp. nov. (broken line); 6. Gyrodactylus costaricensis Kritsky & Fritts, 1970 (re – examination); 7. Overlay of G. costaricensis with G. j a ro c h o sp. nov. (broken line); 8. Overlay of G. costaricensis with G. xalapensis sp. nov. (broken line); 9. Gyrodactylus cytophagus Paperna, 1968 (reexamination); 10. Overlay of G. cytophagus with G. ja ro c ho sp. nov. (broken line); 11. Overlay of G. cytophagus with G. xalapensis sp. nov. (broken line); 12. Gyrodactylus gambusiae Rogers & Wellborn, 1965 (re-examination); 13. Overlay of G. gambusiae with G. j a ro c h o sp. nov. (broken line); 14. Overlay of G. gambusiae with G. xalapensis sp. nov. (broken line). Scale bars = 3 µm.

FIGURES 32 – 38. Gyrodactylus jarocho sp. nov. from Xiphophorus hellerii Heckel. 32. Light micrograph of the haptoral central hook complex showing the hamuli, the dorsal and the ventral bar (ventral view); 33. Light micrograph of the marginal hook; 34 – 35. Light micrographs of the marginal hook sickles; 36. Drawing of the central hook complex; 37. Drawing of the marginal hook sickle; 38. Drawing of the male copulatory organ (MCO). Scale bars: Figures 32, 33 and 36 = 5 µm; Figures 34, 35, 37 and 38 = 3 µm.

Tables

TABLE 3. Morphological measurements of Mexican Gyrodactylus spp., including new species, new host and new locality records.

Measurement	G. j a roc ho sp. nov. from Xiphophorus hellerii (n = 4)*	G. x al ap ens is sp. nov. from Heterandria bimaculata (n = 8)*	G. bullatarudis from Poecilia mexicana (n = 8)*	G. bullatarudis from Xiphophorus hellerii (n = 6)*
TBL	323 1	262 (245–275)	418 (370–465)	345 1
TBW	78 1	68 (60–75)	120 (110–130)	112 1
OL×W	85 × 60 1	53 (50–55) × 54 (50–58)	73 (70–75) × 72 (67–76)	64 × 64 1
APL×W	–	13.7 × 30.4 1	13.0 (8.9–17.0) × 39.1 (38.5–39.7)	19.0 × 30.7 1
PPL×W	–	12.9 × 42.7 1	15.9 (11.7–20.0) × 43.2 (41.5–44.8)	13.2 × 39.7 1
MCOL×W (NoS)	11.0 × 8.7 (8 spines: 2 medium (2.3 ± 0.19) interspersed with 6 smaller (1.6 ± 0.32))1	11.9 × 10.4 (4 spines: 2 medium upwardly pointing terminal spines, 2 small central spines)1	15.0 × 16.8 (6 spines)1	10.9 × 11.5 1 (5? spines)
Hamulus
HTL	67.1 ± 1.03 (66.3–68.6)	47.2 ± 1.99 (43.3–49.6)	53.3 ± 1.29 (50.9–54.5)	57.4 ± 3.7 (55.0–64.9)
HA	29.7 ± 0.66 (28.9–30.3)	16.0 ± 1.39 (14.3–18.1)	18.7 ± 0.94 (17.6–20.3)	18.3 ± 0.59 (17.4–18.8)
HPSW	8.6 ± 0.28 (8.3–8.9)	6.8 ± 0.47 (6.0–7.5)	7.7 ± 0.51 (7.2–8.9)	8.6 ± 0.18 (8.5–8.9)
HPL	26.6 ± 0.50 (25.9–27.1)	21.4 ± 1.64 (19.1–23.4)	24.8 ± 0.99 (22.6–25.9)	25.4 ± 0.65 (24.4–26.1)
HDSW	3.9 ± 0.68 (3.6–4.9)	3.9 ± 0.18 (3.6–4.3)	4.2 ± 0.24 (3.8–4.5)	4.8 ± 0.32 (4.3–5.1)
HSL	44.0 ± 0.43 (43.6–44.6)	31.3 ± 1.07 (30.2–32.6)	34.2 ± 0.72 (33.1–35.2)	35.6 ± 0.92 (34.4–37.0)
HICL	1.7 ± 0.46 (1.0–2.1)	1.7 ± 0.35 (1.3–2.4)	1.4 ± 0.18 (1.1–1.7)	1.7 ± 0.50 (0.8–2.4)
HAA°	46.8 ± 0.64 (46.2–47.7)	32.2 ± 2.80 (28.6–36.3)	36.4 ± 1.86 (34.9–39.9)	33.4 ± 1.47 (31.9–35.7)
HPCA°	6.5 ± 0.66 (5.7–7.3)	6.7 ± 1.34 (5.0–8.7)	1.1 ± 0.58 (0.5–2.5)	5.6 ± 1.36 (2.9–6.8)
IHAA°	51.3 ± 0.77 (50.5–52.0)	35.9 ± 4.19 (30.1–41.9)	40.7 ± 2.77 (35.1–44.7)	37.7 ± 1.93 (36.2–41.2)
HRL	25.6 ± 0.57 (24.9–26.3)	11.9 ± 0.93 (10.3–13.7)	17.4 ± 1.11 (16.0–19.2)	17.7 ± 0.67 (16.6–18.3)
Ventral bar
VBL	32.3 ± 3.73 (29.3–37.7)	30.7 ± 2.75 (26.4–34.7)	31.3 ± 1.84 (29.4–35.8)	32.8 ± 0.84 (31.9–34.1)
VBW	29.2 ± 1.23 (27.9–30.6)	30.3 ± 1.26 (27.9–32.1)	28.3 ± 1.95 (25.3–32.3)	29.2 ± 0.61 (28.4–29.7)
VBPML	10.5 ± 0.38 (9.9–10.9)	10.7 ± 1.56 (7.9–12.1)	10.9 ± 1.15 (9.1–13.0)	12.1 ± 0.64 (11.1–13.0)
VBML	6.9 ± 0.48 (6.6–7.7)	5.2 ± 0.37 (4.7–5.6)	5.9 ± 0.24 (5.5–6.2)	5.9 ± 0.44 (5.2–6.4)
VBPL	9.1 ± 0.59 (8.5–9.9)	10.9 ± 1.35 (8.7–12.4)	9.4 ± 0.78 (8.4–10.8)	11.5 ± 1.02 (10.3–12.6)
VBMemL	14.7 ± 4.71 (11.7–21.7)	15.0 ± 1.45 (12.3–16.5)	14.8 ± 1.42 13.5–17.7)	14.8 ± 0.82 (13.6–15.6)
Dorsal bar
DBL	28.6 ± 1.10 (27.6–29.8)	22.2 ± 1.89 (19.4–25.7)	25.1 ± 1.77 (22.7–27.5)	27.3 ± 0.25 (27.0–27.6)
DBW	0.7 ± 0.11 (0.6–0.9)	1.7 ± 0.35 (1.1–2.3)	1.4 ± 0.33 (0.9–1.8)	1.5 ± 0.38 (1.0–1.9)
Marginal hooks
MHTL	28.8 ± 1.17 (27.9–30.3)	25.8 ± 1.05 (24.5–27.2)	25.2 ± 1.33 (23.5–26.9)	26.2 ± 0.65 (25.3–27.0)
MHSL	22.7 ± 1.12 (21.7–24.3)	20.9 ± 0.86 (20.2–22.3)	20.1 ± 1.66 (17.9–23.5)	20.9 ± 0.56 (20.4–21.7)
MHSiL	6.5 ± 0.10 (6.4–6.6)	5.0 ± 0.21 (4.7–5.3)	5.5 ± 0.16 (5.3–5.8)	5.6 ± 0.07 (5.5–5.7)
MHSiPW	4.7 ± 0.00	4.1 ± 0.28 (3.5–4.4)	4.2 ± 0.44 (3.6–4.8)	4.4 ± 0.21 (4.1–4.7)
MHToeL	2.0 ± 0.14 (1.9–2.2)	1.6 ± 0.18 (1.3–1.8)	1.9 ± 0.21 (1.5–2.1)	1.9 ± 0.24 (1.8–2.4)
MHSiDW	3.5 ± 0.37 (3.2–4.0)	3.4 ± 0.26 (3.0–3.8)	1.9 ± 0.28 (1.5–2.3)	2.3 ± 0.30 (1.9–2.6)
MHA	6.1 ± 0.27 (5.9–6.5)	4.3 ± 0.12 (4.0–4.4)	5.1 ± 0.26 (4.7–5.6)	5.0 ± 0.20 (4.8–5.3)
MHI/AH	0.5 ± 0.06 (0.4–0.6)	0.6 ± 0.09 (0.4–0.7)	0.6 ± 0.07 (0.5–0.7)	0.5 ± 0.06 (0.4–0.5)