Dactylogyrus yassensis, Musilová, Na Ď A, Ehulková, Eva Ř & Gelnar, Milan, 2009

Musilová, Na Ď A, Ehulková, Eva Ř & Gelnar, Milan, 2009, Dactylogyrids (Platyhelminthes: Monogenea) from the gills of the African carp, Labeo coubie Rüppell (Cyprinidae), from Senegal, with descriptions of three new species of Dactylogyrus and the redescription of Dactylogyrus cyclocirrus Paperna, 1973, Zootaxa 2241, pp. 47-68 : 55-57

Dactylogyrus yassensis n. sp.

( Figure 7 , Table 1 )

Synonym: Dactylogyrus cyclocirrus Paperna, 1973 of Guégan et al. (1988).

Type host and locality: Labeo coubie , Gambia River near the Campement du Lion (13º 01.493’N; 13º 14.491’W), Niokolo-Koba National Park, Senegal.

Other records: Labeo senegalensis , Niger River (Bamako), Baoulé River (Missira), Mali; Guiers Lake, Senegal, ( Guégan et. al. 1988); Labeo coubie , Gambia River near the hotel Simenti (sand beach 13° 01.543’N; 13º 17.471’W, gravel beach 13º 01.395’N; 13º 17.350’W), Niokolo-Koba National Park, Senegal.

Site: Gill lamellae.

Type specimens: Holotype RMCA 37646; 2 paratypes RMCA 37647, 37648.

Material examined: 1 unflattened and 3 flattened specimens in GAP.

Comparative material examined: Dactylogyrus cyclocirrus Paperna, 1973: 12 syntypes RMCA M.T. 35.699 from Labeo cylindricus , 3 paratypes RMCA M.T. 35.700 from L. victorianus (see Paperna 1979); D. omega Guégan & Lambert, 1991 : paratype MNHN HC 452 (Tj 239) from L. rouaneti .

Etymology: The species name refers to the yassa, a very popular dish in Senegal.

Description: Body length 571; greatest width 117. Haptor 95 long, 127 wide. Single pair of anchors (dorsal): inner length 38 (38–39; n = 3); outer length 36 (35–38; n = 3); inner root truncate, 13 (12–14; n = 3) long; outer root blunt, 6 (5–7; n = 3) long; curved shaft slightly swollen at level of filament hitch; point not reaching level of tip of inner root, 11 (9–12; n = 3) long. Anchor filaments well-developed. Two bars: dorsal bar bone like, with short truncate posteromedial process, 26 (26–27; n = 3) long, 5 (5–7; n = 3) wide; ventral bar reduced in size, vestigial, 7 (6–7; n = 3) long, 1 (1–2; n = 3) wide. Hooks 7 pairs, dissimilar in size; hook lengths (n = 2): pair I = 20; pair V = 22; pairs II, III, IV, VI and VII = 17 (16–18). Needles (1 pair) located near hooks of pair V. No sclerotized vagina observed. Copulatory organ a coiled wide tube of about 1.5 rings, with large base lacking flange; total length 38 (35–43; n = 3); tube trace-length 76 (74–79; n = 3). Accessory piece slightly sclerotized, articulated to base.

Remarks: Based on the drawings of the sclerotized structures, this species markedly resembles D. cyclocirrus Paperna, 1973 from Labeo victorianus ( Paperna 1979) and from L. senegalensis ( Guégan et al. 1988) , and D. omega Guégan & Lambert, 1991 from L. rouaneti ( Guégan & Lambert 1991) . The former species was described briefly and incompletely (i.e. without drawings of sclerotized structures) by Paperna (1973) on the gills of L. cylindricus (type host) from Ruaha River ( Tanzania), L. victorianus from Nzoia River ( Kenya), L. senegalensis and L. coubie from Volta Lake ( Ghana). Six years later, this author supplemented the original description with drawings of the sclerotized structures of D. cyclocirrus collected from L. cylindricus and L. victorianus , and pointed out considerable morphometric variations in sclerotized structures depending on host species and locality (see Paperna 1979). Indeed, Paperna’s (1979) drawings of the sclerotized structures and our examination of the type specimens of D. cyclocirrus revealed that the description of this parasite was obtained from two morphologically different species. Although the type specimens available to us were in poor condition, features of visible sclerotized structures clearly show the non-conspecificity of the specimens from L. cylindricus (syntypes RMCA M.T. 35.699) and specimens from L. victorianus (paratypes RMCA M.T. 35.700), based on the size and morphology of the anchors, dorsal bars, and hooks (compare Fig. 8 II with Fig. 8I ). Furthermore, Paperna (1979) did not depict the vestigial ventral bar, which we observed only in the specimens from L. victorianus and whose presence distinguishes these specimens from the specimens collected from L. cylindricus . On top of that, the parallel designation of syntypes and paratypes within the same type series is wrong, based on the “name-bearing types fixed in the original publication (holotypes and syntypes)” (Article 73, 1999 ICZN). In view of our findings above and the fact that Paperna (1979) designated L. cylindricus as the type host of D. cyclocirrus , we designate the lectotype for this species of Dactylogyrus from the syntypes collected from this host only (see Fig. 8 II).

Overlooking Paperna’s (1979) mistake, Guégan et al. (1988) identified their Dactylogyrus specimens from L. senegalensis as D. cyclocirrus , probably based on the morphological similarity between their specimens and the specimens from L. victorianus ( Paperna 1979) . Further, our comparison of their drawings of the sclerotized structures with Paperna’s (1979) “ paratypes ” of D. cyclocirrus revealed small differences in the morphology of the anchors and dorsal bars. Anchors of D. cyclocirrus reported by Guégan et al. (1988) are larger and with a shorter point than those in Paperna’s (1979) “ paratypes ”. On the other hand the dorsal bar described by the former authors is smaller in relation to anchor size than that in the “ paratypes ” of D. cyclocirrus (compare Fig. 3 of Guégan et. al (1988) with Fig. 8I presented herein). Based on the abovementioned differences we believe that the specimens from these two host species belong to two different Dactylogyrus species. However, the morphology of all sclerotized structures (i.e. haptoral sclerites and copulatory organ) in specimens collected by us from L. coubie is in agreement with that reported by Guégan et al. (1988) in the record of D. cyclocirrus . Therefore, we consider D. cyclocirrus of Guégan et al. (1988) from L. senegalensis to be an older subjective synonym of D. yassensis n. sp.

This new species is confused easily with D. omega described by Guégan and Lambert (1991) on L. rouaneti (see Fig. 9 ) from Guinea and on L. parvus from Sierra Leone and Ivory Coast. However, these species are distinguished by the fact that D. yassensis n. sp. possesses: (1) a larger anchors; (2) a shorter point not reaching the level of the tip of inner anchor root (extending past level of tip of inner anchor root in D. omega ); (3) a dorsal bar smaller in relation to anchors size; and (4) a copulatory tube with noticeably larger diameter (see Tab. 1 , Figs. 7 and 9 ). Although the comparative morphology of corresponding structures does not differ markedly, the designation of D. yassensis n. sp. is supported also by Guégan and Lambert (1991) who distinguished their D. omega from D. cyclocirrus of Guégan et al. (1988) by the different tube diameter of their copulatory organs.

D. yassensis n. D. cyclocirrus D. omega Character sp.

Host and locality: Labeo victorianus, Nzoia River, Kenya, ( Paperna 1973).

Site: Gill lamellae.

Material examined: Dactylogyrus cyclocirrus Paperna, 1973: 3 syntypes (originally erroneously designated as paratypes) RMCA M.T. 35.700 from L. victorianus (see Paperna 1979).

Remarks: As a result of our examination of the type specimens of D. cyclocirrus , it was found that Paperna’s (1979) type series contains two distinct species (see Remarks on D. yassensis n. sp.). Based on the morphology of the sclerotized structures, the specimens from L. victorianus (syntypes RMCA M.T. 35.700) is intermediate between D. omega and D. yassensis n. sp. by having an anchor point extending past level of tip of inner root, similar to that of D. omega , and a wide copulatory tube diameter (i.e. 4–5; n = 2) like that of D. yassensis n. sp. (see Tab. 1 ). However, the available specimens are insufficient for description and therefore we believe they only reflect undescribed species.

Figures

FIGURE 3. Dactylogyrus titus Guégan, Lambert & Euzet 1988. A. anchor; B. dorsal bar; C. hook; D. needle; E. copulatory organ.

FIGURE 7. Dactylogyrus yassensis n. sp. A. anchor; B. ventral bar; C. dorsal bar; D. hooks (pairs I – V = ventral, pairs VI, VII = dorsal); E. needle; F. copulatory organ.

FIGURE 9. Dactylogyrus omega Guégan & Lambert, 1991 from Labeo rouaneti (paratype MNHN HC 452 (Tj 239 )). A. anchor; B. ventral bar; C. dorsal bar; D. hooks; E. copulatory organ. Needles indistinct.

FIGURE 8. I. Dactylogyrus sp. from Labeo victorianus originally described by Paperna (1973) as D. cyclocirrus (one of the specimens on the slide RMCA M. T. 35.700). A. anchor; B. ventral bar; C. dorsal bar; D. hooks; E. copulatory organ. II. Dactylogyrus cyclocirrus Paperna, 1973 from Labeo cylindricus (lectotype circled on the slide RMCA M. T. 35.699). A. anchor; B. dorsal bar; C. hooks; D. copulatory organ. Needles not observed.

Tables

TABLE 1. Comparative morphometric measurements (in μm) for Dactylogyrus yassensis n. sp., Dactylogyrus cyclocirrus Paperna, 1973, Dactylogyrus cyclocirrus of Guégan et al. (1988), and Dactylogyrus omega Guégan & Lambert, 1991.

	Present study	Paperna (1979)	Guégan et al. (1988)	Guégan & Lambert (1991)
	Mean (Range)	Mean (Range)	Mean (Range)	Mean (Range)
Body total length	571 (540–638)	420	580 (430–700)	530 (360–830)
Anchor inner length	38 (38–39)	30–33	39 (36–42)	35 (32–36)
outer length	36 (35–38)	–	37 (34–42)	28 (26–30)
inner root length	13 (12–14)	–	13 (11–16)	12 (10–14)
outer root length	6 (5–7)	3–4	7 (4–10)	5 (3–6)
point length	11 (9–12)	9–14	14 (12–16)	14 (13–15)
Dorsal bar total length	26 (26–27)	24–30	27–35	24–28
median width	5 (5–7)	–	5–8	4–6
Ventral bar total length	7 (6–7)	–	6–7	4–6
median width	1 (1–2)	–	–	–
Hooks total length	16–22	8	14–30	15–22
Copulatory organ total length	38 (35–43)	–	33–46	35–42
tube trace-length	76 (74–79)	60	55–60	–
tube diameter	4–5	–	–	2–3
Host	L. coubie	L. victorianus	L. senegalensis	L. rouaneti , L. parvus
Locality	Senegal	Kenya	Mali	Guinea, Sierra Leone, Ivory Coast
Dactylogyrus sp. (Figure 8I, Table 1)