Bagrobdella vansteenbergei Mushagalusa Mulega & Pariselle, 2022

Mulega, Archimède Mushagalusa, Bukinga, Fidel Muterezi, Akoumba, John Francis, Mulungula, Pascal Masilya & Pariselle, Antoine, 2022, Monogeneans from Catfishes in Lake Tanganyika. I: Two new species of Bagrobdella (Dactylogyridae) from Auchenoglanis occidentalis (Siluriformes: Claroteidae), Zoologia (e 22016) 39, pp. 1-13 : 5-7

Bagrobdella vansteenbergei Mushagalusa Mulega & Pariselle , sp. nov.

Fig. 27

https://zoobank.org/ 47A4EA89-ED69-4878-BFD7-A3F8FC11CA6E

Type-host. Auchenoglanis occidentalis (Valenciennes, 1840) .

Site of infection. gills.

Type locality. Mouth of Mutambala River ( DRC) 29°04.4042’E, 04°16.4598’S .

Studied materiel. 15 specimens mounted in Hoyer’s medium.

Number of hosts examined. 11.

Prevalence. 1/11 = 9%.

Mean intensity. 17/1 = 17.

Abundance. 17/11 = 1.5.

Type-material. Holotype deposited at the Royal Museum for Central Africa, Tervuren , Belgium ( RMCA _VERMES_43658), paratypes deposited at the MRAC (number RMCA _VERMES_43659), the MnHn , Paris , France ( MNHN HEL1825 ) and the Iziko South African Museum , Cape Town , Republic of South Africa ( SAMC) ( SAMC-A094636 and SAMC-A094637 ).

Description. The anatomy is that of Bagrobdella . Total length 621 (543–749, 12), greatest width 182 (113–262; 13); pharynx 64 (42–79; 10). Dorsal anchor a = 71 (67–77; 13), b = 64 (59–70; 13), c = 1 (0–5; 13), d = 10 (7–13; 13), e = 23 (21–26; 13). Dorsal bar x = 88 (77–100; 10), w = 14 (10–18; 10), median projection posteriorly oriented: Y = 55 (51–70; 6). Ventral anchor slightly drilled at the blade proximal extremity: a = 63 (61–67; 13), b = 62 (60–64; 12), c = 6 (4–8; 12), d = 12 (9–17; 12), e = 26 (22–28; 13). Ventral bar: 92 (78–103; 10), w = 14 (11–18; 8), extends in the form of an outgrowth: BL = 7 (5–11; 7), Bl = 5 (5–6; 8). This bar has a median projection posteriorly cross-chapped cx = 77 (69–85; 12), cy = 25 (21–31; 12), absence of sclerotized trapeze-shaped. Hook pairs of similar size: I = 26 (23–31; 11), II = 17 (14–19; 10), III and IV = 22 (19–27; 10), and V up to VII = 19 (18–22; 12). MCO 66 (58–71; 11), asymmetrical bulb AL = 16 (11–20; 9), Al = 9 (5–12; 9), is a curved tube with thick wall and constant diameter; a part of the wall extend the penis extremity of about 25%.

Etymology. The species is named after Dr. Maarten Van Steenberge, a researcher at Royal Belgian Institute of Natural Sciences, who is a specialist in African freshwater fish.

Note: The authors of the new taxa are different from the authors of this paper: Article 50.1 and Recommendation 50A of the International Code of Zoological Nomenclature.

Remarks. The new species was placed in Bagrobdella due to the presence of haptor with dorsal, ventral anchor/bar complexes, 7 pairs of hooks, pairs 1, 3–7 with shanks comprised of 2 subunits, proximal subunit expended, pair 2 with shank of 1 subunit. Ventral bar straight, with long anterior projection, dorsal bar straight, with posterior shield-like projection, which are characteristics of the genus ( Kritsky and Kulo 1999). Bagrobdella vansteenbergei sp. nov. differs from all other species already described by the size of its hooks, which are all of almost the same length (pair I being only slightly longer than the others), whereas they are of different size in all the previously described species (including B. vanhovei sp. nov.) ( Figs 9–14 ). Moreover, the trapezoidal piece was not observed in the 17 individuals (15 Hoyer’s mounted and 2 preserved in ethanol), and the ventral anchors are slightly holed. Its male copulating organ is unique and different from the MCO of B. auchenoglanii , B. fraudulenta , B. anthopenis and B. parauchenoglanii by a shape which is not spirally coiled. As B. vanhovei , the MCO of B. vansteenbergei has a sub-terminal opening at three quarter of the total length. As Bagrobdella vanhovei sp. nov, Bagrobdella vansteenbergei sp. nov, has two small hard parts that have never been reported before in the description of Bagrobdella species. These are: 1) a structure in the shape of a button between the bar and ventral anchors ( Fig. 26 ), 2) a semi-circular structure toping the extremity of the ventral bar median projection ( Fig. 25 ).

Multivariate analyses

Our dataset contained 68 individuals with 21 quantitative variables ( Figs 2–7 ). Among the 68 individuals, three were considered as illustrative ( B. auchenoglanii , B. fraudulenta and B. anthopenis ). The first two dimensions of the PCA represent 71.8% of the total dataset inertia. Individuals are clustered into three groups which correspond to the three species included in the analysis ( Bagrobdella vanhovei sp. nov., B. vansteenbergei sp. nov., and Bagrobdella pauchenoglanii ). Only parameters contributing to more than 95 percent for group separation were displayed on the graph ( Fig. 28 ). The dimension 1 opposes most individuals belonging to the group B. vanhovei sp. nov. (to the right of the graph, characterized by a positive coordinate on the axis) to individuals belonging to the groups B. vansteenbergi and B. parauchenoglanii (from Cameroon), to the left of the graph, characterized by a strongly negative coordinate on the axis).

The individuals belonging to the group B. vanhovei sp. nov. (characterized by a positive coordinate on the axis) are sharing:

1) high values for III_IV, DA_d, DB_w, I, VA_b, DA_a, VB_x, VA_a, VA_d and DA_b (variables are sorted from the strongest); 2) low values for VA_e and Pe (variables are sorted from the weakest).

The individuals belonging to B. parauchenoglanii (characterized by a negative coordinate on the axis) are sharing: 1) high values for the variables Pe, VA_c, DA_c and VB_w (variables are sorted from the strongest); 2) low values for the variables DA_b, DB_.x, VB_x, cx, VA_a, DA_a, VA_b, DA_e, III_IV and DA_d (variables are sorted from the weakest).

In the group of B. vansteenbergei sp. nov. (characterized by a negative coordinate on the axis) individuals share: 1) high values for the variables VA_e and DA_e (variables are sorted from the strongest); 2) low values for the variables V_à_VII, DA_c, VA_c, IDB_w, DA_d, DV_d, VB_w and III_IV (variables are sorted from the weakest).

The dimension 2 opposes individuals belonging to B. parauchenoglanii (to the top of the graph, characterized by a strongly positive coordinate on the axis) to individuals belonging to B. vansteenbergei sp. nov.

On the graph, B. auchenoglanii and B. anthopenis are isolated from the other species, while B. fraudulenta grouped with B. parauchenoglanii , even so these two latter species being easily distinguishable (at least by their penis morphology) ( Figs 15–20 ).

Figures

Figure 27. Bagrobdella vansteenbergei sp. nov., haptoral structure and MCO. Scale bar: 20 µm.

Figure 28. PCA-Biplot of species belonging to Bagrobdella.

Figures 9–14. Haptors of the six species belonging to Bagrobdella: (9) Bagrobdella vanhovei sp. nov.; (10) Bagrobdella vansteenbergei sp. nov.; (11) Bagrobdella auchenoglanii; (12) Bagrobdella fraudulenta; (13) Bagrobdella anthopenis; (14)Bagrobdella parauchenoglanii (Akoumba et al 2017, Euzet and Le Brun 1990). Scale bars: 20 µm.

Figures 21–26. (21) Bagrobdella vanhovei sp. nov. microphotograph in toto; (22) Bagrobdella vansteenbergei sp. nov. microphotograph in toto; (23) Microphotograph of the trapezoidal plate in the haptor of Bagrobdella vanhovei; (24) Button like structure; (25) Semi-circular structure; (26) Egg (B. vanhovei sp. nov). Scale bars: 21 = 100 µm, 22 = 200 µm, 23, 24, 26 = 20 µm, 25 = 50 µm.

Figures 2–7. Measurement scheme of the sclerotized structures of Bagrobdella spp.: (2) anchor, a: total length; b: blade length; c: shaft length; d: guard length; e: point length. (3) Dorsal bar, x: horizontal length; y: vertical length; w: width. (4) Ventral bar, x: horizontal length; cx: length of median projection; cy: width of median projection; BL: length of outgrowth; Bl: width of outgrowth. (5) Trapezoidal piece, L: length; l: width. (6) Male copulatory complex, Pe: length of penis, AL: length of bulb; Al: width of bulb. (7) Length of hook.

Figures 15–20. MCO of the six species belonging to Bagrobdella: (15) Bagrobdella vanhovei sp. nov.; (16) Bagrobdella vansteenbergei sp. nov.; (17) Bagrobdella auchenoglanii; (18) Bagrobdella fraudulenta; (19) Bagrobdella anthopenis; (20) Bagrobdella parauchenoglanii (Akoumba et al. 2017, Euzet and Le Brun 1990). Scale bar: 20 µm.