Monopylidium comoensis, Mariaux, 2021

Mariaux, Jean, 2021, Two new species of Cestoda (Cyclophyllidea: Dilepididae) from Ploceidae and Passeridae (Aves: Passeriformes) in Côte d’Ivoire, Revue suisse de Zoologie 128 (2), pp. 469-475 : 472-474

Monopylidium comoensis sp. nov.

Figs 6-9

Holotype: MHNG-PLAT-0016113 (formerly MHNG 987.276); Côte d’Ivoire, Zanzan, Ouango Fitini, Northern edge of Comoé National Park, surroundings of former airfield; WGS84 9.58, -4.01; 300 m; 22.01.1987. From Gymnoris dentata (Sundevall, 1850) ( Passeriformes , Passeridae ).

Paratype: MHNG-PLAT-0016112 (formerly MHNG 987.275); MHNG-PLAT-0137403 (formerly MHNG 987.276). Same data as holotype. MHNG- OIS-1773.015 .

Comparison material studied: MHNG- PLAT-0044433, 1 slide. Monopylidium barbara ( Meggitt, 1926) , “cotype”.

Prevalences: 2/17 (12%).

Intensity: 2.

Etymology: The species is named after the National Park of the Comoé, and the eponym river flowing through it, in the North Eastern corner of the Côte d’Ivoire.

Description: Worm with body of medium size, up to 33 mm in length and with maximum width of 1000 at level of early gravid proglottides. Longest specimen with 139 proglottides, but fully gravid specimens must be longer. Proglottides craspedote, wider than long, progressively becoming square then longer than wide when pregravid (up to 1.6x longer than wide in our material). Scolex elongated, quite narrow and pointed, well delineated from neck, 138 in diameter (n = 2). Suckers small, rounded, muscular, unarmed, 60-68 (64, n = 8) [62-68] in diameter. Rostellar sac very large, cylindrical, very glandular, extending past level of posterior margin of suckers, 162 x 68 (n = 1). Rostellum elongated, with well-developed glandular tissue, 105 x 30 (n = 1) ( Fig. 6 ). Hooks very short, on two poorly demarcated rows, 20-22 in number [20]; similar in shape in both rows, with short blades, strong handles and long, very slightly curved handles. Hooks from first row marginally shorter than those from second row. Hooks length 13.5-15.5 on first row (14.5, n = 9) and 14.5-16.5 on second row (15.5, n = 9) ( Fig. 7 ). Neck well-marked; proglottization distinct at about 220-270 from posterior margin of suckers. Genital pores lateral, opening at about 25-30% of lateral proglottis margin length, irregularly alternating in very short series, with some zones of regular alternations. e.g. …, 2, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 2, 1, …; no more than 5 consecutive pores observed on a single side. Ventral osmoregulatory canals generally 25-35 (but up to 50) wide, connected posteriorly in each proglottis by transverse anastomosis. Dorsal osmoregulatory canals narrow 3-5 wide. Genital ducts passing between osmoregulatory canals. Genital atrium small, sinkshaped, up to about 25 deep and 30-40 in diameter.

Testes numerous, 14-25 (19, n = 34) [16-22] in number; in a single layer, in one continuous, posterior field, extending anteriorly to posterior level of ovary ( Fig. 8 ). External vas deferens convoluted antero-porally. Cirrussac weakly muscular, straight, long, 172-212 x 38-60 (195 x 44, n = 22); always crossing osmoregulatory canals. Internal vas deferens forming several coils. Cirrus armed, lined with very small spines ( Fig. 9 ).

Vitellarium central, compact, subglobular, usually somewhat transversely elongated, but variable in shape; 85-125 x 55-95 (102 x 73, n = 12). Ovary, antero-central, clearly bi-winged and multilobulated, with about 5-6 deep main lobules on each side. Mehlis’ gland globular, anterior to vitellarium, in between ovary wings. Seminal receptacle elongated to oval; discrete; reaching up to 112 x 73; dorsal and slightly anterior to ovary wings. Vagina opened posteriorly to male pore, straight and transverse, long, possibly reaching up to seminal vesicle, parallel and ventral to cirrus-sac; particularly thick walled, surrounded by a compact sheath of large cells; its poral opening often enlarging in a well marked V-shaped, funnel like structure ( Figs 8, 9 ).

Eggs appearing progressively, alone or in small groups in the whole parenchyma, with uterus border not clearly visible. Uterus becoming densely reticulate/multilocular, but its final stage of development, as well as fully developed eggs not available in our material.

Remarks: This material belongs to the genus Monopylidium Fuhrmann, 1899 as defined by Spasskii (1993) and accepted by Mariaux & Georgiev (2018). A list of species in this genus, together with a summary of their main characters was provided by Mariaux & Georgiev (2018, see their table 3), and most of them can easily be distinguished from the present material on the basis of their different rostellar hooks size and number; testes number or cirrus sac dimensions.

Two species are however similar to our specimens: M. passerinum Fuhrmann, 1907 was found in Passeriformes , including various Passeridae ( Matevosyan, 1963) and has a large distribution (Palaearctic, Australia). It was initially described by Fuhrmann (1907) and a detailed description was provided by Johnston (1909). Despite their close resemblance, especially in rostellar structures, our material definitely differs from M. passerinum by a lower number of testes (14-25 vs 25-30), and accessorily, by slightly smaller suckers and larger vitelline glands. Additionally, M. barbara (Meggit, 1926) and M. innominata (Meggit, 1926) , both from Yangon, Myanmar (ex Rangoon, Burma) were also described from Passeridae ( Meggitt, 1926) , the latter taxon being subsequently synonymized with the former ( Southwell, 1930). Monopylidium barbara is only succinctly described but essentially differs from the new species in having 23 rostellar hooks. A small fragment of this species cotype, from Passer montanus (Linnaeus, 1758) in Rangoon, was also examined. Only a few male proglottides allow for meaningful observations and they show a shorter cirrus sac (133-150) and a higher number of testes (24-31) than in the original description.Although limited, these observations also allow differentiating M. barbara from the present material.

The Sahel bush sparrow, or bush petronia, Gymnoris dentata , is presently placed within the family Passeridae , but was previously considered a Ploceidae (in the genus Petronia ). Monopylidium comoensis has not been found in any other member of these families during our surveys. In the same locality, bush petronias are also hosts of a Biuterina species that we described previously ( Georgiev & Mariaux, 2007), but are not known to harbor any other cestode throughout their range.

Figures

Figs 6-9. Monopylidium comoensis sp. nov. (6) Scolex. (7) Rostellar hook. (8) Mature proglottis, dorsal view (9) Terminal genitalia. Scale bars: 6, 9: 50 µm; 7: 10 µm; 8: 100 µm.