Schilbetrema ducentesimum Bassock Bayiha, Nack & Pariselle, 2025

Bassock Bayiha, Etienne D., Bahanak, Dieu ne dort, Mbondo, Jonathan A., Nack, Jacques & Pariselle, and Antoine, 2025, Four new species of Schilbetrema (Monogenea: Dactylogyridae) from Schilbe spp. (Siluriformes: Schilbeidae) in the Sanaga River (Sanaga Basin) and Boumba River (Congo Basin) in Cameroon, Zoologia (e 24067) 42, pp. 1-12 : 6

publication ID	https://doi.org/10.1590/S1984-4689.v42.e24067
persistent identifier	https://treatment.plazi.org/id/2425637F-8E7A-FFF0-FF08-FB91873F487C
treatment provided by	Felipe
scientific name	Schilbetrema ducentesimum Bassock Bayiha, Nack & Pariselle
status	sp. nov.

Treatment

Schilbetrema ducentesimum Bassock Bayiha, Nack & Pariselle sp. nov.

Fig. 4 View Figure 4 , Table 2

https://zoobank.org/ E6432CE4-6BD7-47B6-AFD4-245441475749

Type host: Schilbe mystus .

Number of hosts examined: 10.

Site: Gill lamellae.

Prevalence: 40%; mean intensity:10.1 ± 10.

Type locality: Zoulabot ( 03°18.740’ N; 14°04.701’ E, alt. 576 m).

Specimensdeposited:HolotypeRMCA_VERMES_43405; Paratypes RMCA _VERMES_43406–43409 .

Description based on eighth individuals: Dorsal anchors: each with a straight blade, a short outer root, a short and narrow inner root (superficial root, ventral root, guard), and a thick filament, a curved point. Dorsal bar made up of a dumbbell-shaped piece covering a M-shaped structure associated to two light sclerotised parts not yet observable in Schilbetrema and whose origin are unknown. Ventral anchors with a long blade, a small knob at the base of the inner root, a curved point. Ventral bar with elongate bilateral horns, slightly sclerified at their rounded ends, antero-median T-shaped projection, pear-shaped structure associated with tip of antero-median projection. Haptor is armed with seven pairs of hooks, similar in shape (each with truncate thumb, delicate point, slender shank) (even in size) to those of ancyrocephaline oncomiracidia (larval hooks). MCO, tubular, U-shaped and attached to the accessory piece at its proximal part. Accessory piece, straight then digitiform (3 to 4 fingers) at the distal part. Vagina tubular and coiled or sigmoid. The mean and range of measurements of the new species and the sclerotised parts are shown in Table 2.

Etymology: Epithet ducentesimum (Latin for “two hundredth”) refers to the fact that the species represents the two-hundredth taxon described by the senior author (A.P.).

Remarks. By the morphology of the ventral bar (T-shaped, with pear-shaped structure associated with tip of antero-median projection), and the MCO (U-shaped), S. ducentesimum sp. nov. is close to Schilbetrema hexacornis Paperna, 1969 (which has also been described from S. mystus in Ghana). The morphology of the dorsal bar (M-shaped) of S. ducentesimum sp. nov is similar to that of the new species ( S. sanagaensis sp. nov. and S. asambaensis sp. nov.). Schilbetrema ducentesimum sp. nov. differs to S. hexacornis mainly by: (1) the morphology of dorsal bar, which is formed by a single structure in S. hexacornis and other species of Schilbetrema vs two parts (one M-shaped and another part straight and dumbbell shaped) in S. ducentesimum sp. nov.; (2) the length of dorsal anchor (101–108 vs 75–93) and the MCO (148–177 vs 81–92); (3) the presence of two lightly sclerotised parts in S. ducentesimum sp. nov. vs absent or not seen by Paperna (1969) in S. hexacornis . It differs to S. sanagaensis sp. nov. and S. asambaensis sp. nov. mainly by: (1) morphology of MCO (U-shaped in S. ducentesimum sp. nov. and J-shaped in S. sanagaensis sp. nov. and S. asambaensis sp. nov.); (2) MCO length (148–177 vs 66–73 in S. sanagaensis sp.nov., 42–50 in S. asambaensis sp. nov.).