Ophryocotyloides dasi Tandan & Singh, 1964

Mariaux, Jean & Georgiev, Boyko B., 2020, Cestode parasites (Neodermata, Platyhelminthes) from Malaysian birds, with description of five new species, European Journal of Taxonomy 616, pp. 1-35 : 25-27

Ophryocotyloides dasi Tandan & Singh, 1964

Figs 31–32

Material examined

MALAYSIA • 1 spec.; Selangor, University of Malaya’s Gombak Field Station ; 3.32° N, 101.77° E; 280–350 m a.s.l.; 4 Aug. 2010; partial COI sequence, Genbank MN 590292 ; MHNG-PLAT-121155 .

Host

Psilopogon henricii (Temminck, 1831) ( Piciformes , Ramphastidae ; also placed in Megalaimidae ).

Description

Strong worm with body of medium size, 74 mm long; maximum width 2.9 mm at level of gravid proglottides; strobila consisting of 302 proglottides. Proglottides weakly craspedote, always wider than long. Scolex 375 in diameter, separated from strobila by a well-marked constriction. Suckers round to oval, 180–190 (184, n = 4) in diameter; muscular, armed with about 10 dense rows of hooklets, approximately 11–13 in length. Rostellar sac absent, rostellum discoid, 175 in diameter, 90 long, glandular, with weak surrounding muscular layers, armed with two rows of hooks. Hooks 230 in number, with typical davaineid shape, 15.5–16.5 long in both rows. Apical extremity of scolex (pseudoproboscis) tegument covered by distinct minute spines ( Fig. 32 ). Neck 175 in diameter; first proglottides distinct at 1 mm behind posterior margin of suckers. Genital pores unilateral, situated at 20–25% of lateral proglottis margin. Ventral osmoregulatory canals up to 45 wide, connected posteriorly in each proglottis by transverse anastomosis. Dorsal osmoregulatory canals 5–12 wide, connected posteriorly by transverse anastomosis in some proglottides. Genital ducts passing between osmoregulatory canals. Genital atrium regular, inconspicuous, 18–25 deep and 12–20 in diameter.

Testes 30–40 in number (34, n = 17); in 2 unequal fields, one poral consisting of 5–9 testes and one larger antiporal, consisting of 22–31 units (7 and 26, respectively, n = 17); testes rounded, in 2 layers, sometimes in 3 layers antiporally; a few of them may overlap some ovarian lobes. External vas deferens well-marked and oriented transversely, making many loops around a straight line, becoming wider centrally, up to 40 in diameter. Cirrus-sac pear-shaped, thick-walled, with short narrower distal part, almost globular, 120–135 × 68–78 (125 × 72, n = 18), not reaching osmoregulatory canals ( Fig. 33 ). Internal vas deferens 17–25 in diameter, forming a few large coils. Cirrus unarmed.

Vitellarium posterior, central, transversely elongate, compact, with irregular shape, 85–120 × 140–220 (103 × 189, n = 12). Ovary antero-central, fan-shaped, deeply lobated, becoming more massive in advanced mature proglottides. Mehlis’ gland anterior to vitellarium. Seminal receptacle poorly marked, elongate, poral. Vagina opened posteriorly to male pore, straight, surrounded in its distal part by a welldeveloped sheath of large cells, forming small dilation behind cirrus-sac.

Egg developing in entire proglottis, including external to osmoregulatory canals. Uterus apparently saccular although barely visible, no egg capsules. Oncospheres small but no fully-developed eggs observed, as last proglottides in our specimen are filled with calcareous corpuscles.

Remarks

With numerous typical davaineid hooks in 2 rows, armed suckers, unilateral genital pores and an absence of egg capsules, our material belongs to the genus Ophryocotyloides Fuhrmann, 1920 . According to Movsessian (2003b), 6 species of this genus parasitize Piciformes and 3 are found in the genus Psilopogon . All of them have been described from India and show very similar characters. Ophryocotyloides barbeti Singh, 1959 was described from the Brown-headed Barbet, P. zeylanicus (Gmelin, 1788) and O. haemacephala Singh, 1959 from the Coppersmith Barbet, P. haemacephalus (Muller, 1776) . The former taxon can easily be differentiated from our material by its smaller number (150) of longer (22–27) hooks and higher number (10–15) of poral testes. The latter resembles our specimen but has a smaller rostellum (110–160); although the total numbers of testes are comparable, it has a larger poral number of testes according to Singh’s (1959) drawing.

The third species, O. dasi Tandan & Singh, 1964 described from P. haemacephalus , is the most similar to our material on the basis of the description by Tandan & Singh (1964). It only differs in minor details like smaller suckers, which are reported to only bear 6–7 rows of hooklets. Ophryocotyloides dasi is also described with slightly fewer aporal testes (17–21), although the total number just overlaps our own observations. This is not sufficient to differentiate this species from our material with any certainty, as superimposed aporal testes are difficult to differentiate. Finally, Tandan & Singh (1964) reported a vaginal sphincter that is not present in our material (unless they refer to the cellular sheath we have observed). All other characters closely match our measurements. Without access to the type specimens of O. dasi , we consider that the minor differences noted above are not sufficient to distinguish our specimen from this species. In addition, it should be noted that the host of O. dasi and the Yellowcrowned Barbet (in which we found our material) have overlapping geographical ranges. This is the first report of this taxon since its original description. P. henricii is a new host for this species, and this is the first record of O. dasi in SE Asia.

Figures

Figs 31–35. — 31–32. Ophryocotlyoides dasi Tandan & Singh, 1964. 31. Scolex with double crown of hooks, spinuous pseudoproboscis and armed suckers margins. 32. Mature proglottis, ventral view. — 33–35. Variolepis cf. bilharzii (Krabbe, 1869). 33. Scolex. 34. Rostellar hooks. 35. Mature proglottis. Scale bars: 31, 33 = 50 µm; 32 = 250 µm; 34 = 20 µm; 35 = 100 µm.