(Figs. 1B, 4, 5)
Host: Apus affinis (J.A. Gray) (Apodiformes, Apodidae).
Site: small intestine.
Locality: Nesting colony on the building of the Centre International de Recherches Médicales de Franceville, Republic of Gabon, 01°36’59.8”S, 13°34’55.9”E.
Prevalence: 33%.
Mean intensity: 2.0.
Specimens studied: 8 specimens, including 4 entire specimens, 2 specimens without scoleces and two scoleces in Berlese’s medium.
Voucher specimens: MHNG-PLAT-96109, USNM 1422221–1422222, IBER-BAS CES 20170530.18–20.
Description: Body ribbon-shaped, gradually becoming wider in posterior part (Fig. 1B). Maximum length of gravid specimens 49 mm (n=1), maximum width 1.15–1.38 mm (1.26 mm, n=3). Scolex rounded, apical part gradually narrowing, conical (Fig. 4A); maximum width at level of suckers, 337–381 (363, n=4). Rostellum sucker-like, with diameter 161–208 (182, n=4); longitudinal muscular fibres present within rostellum. Rostellar hooks 56–70 (64, n=5) in number, regularly alternating in two rows; anterior and posterior hooks of different size and shape. Anterior hooks 45–49 (47, n=24) long (Fig. 4B), length of guard 7 (n=2), length of blade 17 (n=2), length of handle 20–22 (n=2). Posterior hooks 25–30 (27, n=17) long (Fig. 4C), length of handle 7–10 (8, n=3), blade 10–11 (n=5), base 18 (18, n=2). Suckers oval, with well-developed musculature; diameter 203–242 (219, n=5). Neck 79–247 (168, n=4) wide, not clearly distinguished from scolex; proglottisation begins at 485–530 (503, n=4) from posterior margin of suckers. Fully-developed strobila consisting of 342 proglottides: 147 juvenile, 42 premature, 55 mature, 70 post-mature, 15 pre-gravid and 13 gravid. Proglottides craspedote.
Mature proglottides wider than long in proportion c.1:4. Gravid proglottides wider than long in proportion c.1:2. Genital pores irregularly alternating in short series, i.e....3, 5, 1, 4, 1, 3, 3, 2, 3, 2, 2, 1, 1, 3, 2, 1, 2,… or…1, 1, 1, 1, 1, 2, 3, 1, 2, 5, 6, 1, 2, situated in middle of lateral margin of proglottis. Genital atrium simple (Fig. 4E), 12– 37 (17, n=28) deep, its orifice 5–30 (14, n=28) in diameter and base 5–22 (10, n=28) wide, surrounded by intensely stained glandular cells. Ventral osmoregulatory canals with diameter 12–47 (25, n=30), with transverse anastomosis along posterior margin of each proglottis. Dorsal osmoregulatory canals with diameter 5–12 (9, n=25), without anastomoses. Genital ducts ventral to osmoregulatory canals.
Testes 12–15 (14, n=17) in number, situated in median field dorsally to female glands and may overlap osmoregulatory canals (Fig. 4D); diameter of testes 45–74 (60, n=6). External vas deferens with diameter 12–17 (13, n=30), coiled, forming compact body situated near anterior margin in poral lateral field and in poral anterior part of median field. Internal vas deferens coiled, with diameter 5–12 (8, n=30). Cirrus sac thick-walled, elongate, 101–161 (126, n=28) long and 25–54 (38, n=30) wide, oblique to lateral margin of proglottis (Fig. 4E). No evaginated cirrus in specimens available.
Vitellarium compact, with irregular shape, 87–121 (102, n=20) wide, dorsal to ovary, adjacent to posterior margin of proglottis (Fig. 4D). Ovary reniform, compact, 208–307 (263, n=10) wide, occupying whole width of median field anteriorly and ventrally to vitellarium. Mehlis’ gland spherical or with irregular shape, with diameter 25–45 (34, n=20), antero-dorsal to vitellarium. Vagina thin-walled, with diameter 7–13 (10, n=29); vaginal lumen surrounded by thin cellular sheath (Fig. 4E); vagina passing posteriorly and opening postero-dorsally to orifice of cirrus sac; conductive part length 20–40 (29, n=4) and width 5–7 (6, n=4), slim, situated at crossing point of osmoregulatory canals and vagina. Seminal receptacle cylindrical, sigmoid, 25–30 (27, n=6) wide.
Uterus starts developing simultaneously with female glands, initially as thin-walled transversely-elongate sac situated antero-dorsally to ovary (Fig. 4D), almost as dorsal as testes in mature proglottides. With increasing size of uterus, testes pushed out laterally and dorsally, and uterus gradually occupying entire medium field (Fig. 5A). Uterine walls forming internal outgrowths in post-mature proglottides; simultaneously, paruterine organ starts developing as a densification of medullar parenchyma situated anteriorly to uterus (Fig. 5B). In pre-gravid and gravid proglottides, lateral and posterior uterine walls become irregular, forming large outgrowths, with eggs situated between them (Fig. 5C). In some specimens, majority of eggs situated in anterior part of uterus embraced by paruterine organ in last gravid proglottides. External shell of eggs (Fig. 4F) thin, with irregular shape, 37–62 (48, n=21) wide. Oncospheres with diameter 25–35 (30, n=22). Embryonic hooks: median pair 20–27 (22, n=22) long, internal lateral pair 15–20 (17, n=22) long and external lateral pair 10–12 (11, n=17) long.
B A C D А B C Remarks. The present material belongs to the second group of species of Notopentorchis (defined above) characterised by a larger body, anterior rostellar hooks with a shape differing from that of the posterior rostellar hooks and considerably longer than them, an elongate cirrus sac and a transversely elongate developing uterus (Table 2). On the basis of their morphology, our specimens belong to N. vesiculigera. This species is a widespread parasite of swifts in temperate latitudes of Eurasia: Denmark (Krabbe 1882), Ukraine (Kornyushin 1989), the European part of Russia (Dogiel & Karolinskaya 1936) and the Russian Far East (Krotov 1952; Oshmarin 1963). There is also a record from Apus caffer from the Democratic Republic of the Congo (Baer 1959), which is accompanied with brief morphological data, i.e. 50 rostellar hooks with length 50 µm and 29 µm. In the same paper, Baer (1959) considered Biuterina dikeniensis Mokhehle, 1951 from A. caffer from the Republic of South Africa, erroneously cited by Baer (1959) and Georgiev & Bray (1991) as Sphaeruterina dikeniensis, as a synonym of N. vesiculigera.
The records of N. vesiculigera from Switzerland (Fuhrmann 1926), France (Joyeux & Baer 1936) and Spain (López-Neyra 1944), accompanied with descriptions, do not fit with the description of N. vesiculigera and should be related to the other widespread Palaearctic species, N. iduncula. The present material fits very well with the descriptions of N. vesiculigera provided by Krabbe (1882) and Kornyushin (1989), both from Apus apus, including relative to the metrical data (Table 2). We report N. vesiculigera from Apus affinis for the first time.