Indopolystoma elongatum, Chaabane & Verneau & Preez, 2019

Chaabane, Amira, Verneau, Olivier & Preez, Louis Du, 2019, Indopolystoma n. gen. (Monogenea, Polystomatidae) with the description of three new species and reassignment of eight known Polystoma species from Asian frogs (Anura, Rhacophoridae), Parasite (Paris, France) 26 (67), pp. 1-18 : 6-9

Indopolystoma elongatum n. gen. n. sp.

( Figs. 5 and 6 ; Table 4)

urn:lsid:zoobank.org:act:EDFE29A4-9B26-4A25-A92A-BB3CF106D4EC

Synonym: Polystoma sp. of Badets et al. [ 2] and Héritier et al. [ 22].

Type-host: Rhacophorus arboreus (Okada & Kawano) . Now Zhangixalus arboreus (Okada and Kawano) [ 21, 27].

Site: Bladder.

Type-locality: Upstream of Kunigami-gun, city of Nago, Okinawa prefecture, Japan.

Other localities: Sado Island, Niigata prefecture, Japan.

Collector: Professor Hideo Hasegawa, Department of Biology , Oita Medical University, Hasama, Oita 879-5593, Japan .

Type-specimens: Holotype ( MNHN HEL1184 ) and 2 paratypes ( MNHN HEL1185 – HEL1186 ) deposited in the A. Chaabane et al.: Parasite 2019, 26, 67

7

Parasite Collection, National Museum of Natural History, Paris, France.

Etymology: The species name elongatum refers to its general body shape, which is elongate.

Description

Description based on three flattened specimens stained in carmine and mounted in Canada balsam. Body elongate, tapered anteriorly, total length 14,791 (12,847 –14,878), including haptor; greatest width 3182 (3170–3270); width at vagina 1967 (1902–2031). Tegument smooth. Haptor sub-rectangular, 916 (734–1098) long, 1661 (1512–1810) wide. Haptor/total body length ratio 0.06 (0.05–0.07). Suckers 420 (380–459) in diameter. Hamuli 407 (303–419) long; with hook 78.5 (72–85) long ( Fig. 6A–A ’’’). Marginal hooklet C1 36 long; C2–C8 23 (18–32) long ( Fig. 6B–B ’’). Mouth ventral, sub-terminal and surrounded by false oral sucker; false oral sucker 551 (528–573) wide. Pharynx pyriform, 237 (227–247) long, 259 (256–268) wide. Oesophagus not visible. Intestine bifurcate with medial diverticula highly branched giving rise

A. Chaabane et al.: Parasite 2019, 26, 67 9 to prehaptoral anastomoses (up to two). Testis not visible hidden by the digestive tract and vitellaria. Seminal vesicle prominent and packed with sperm. Genital bulb slightly sclerotized, medio-ventral, 139 (129–211) in diameter, with eight sclerotized genital spines; genital spines 41 (38–44) long. Ovary prominent, submedian and packed with oocytes; ovary 1072 (1062–1108) long, 520 (514–563) wide. Ootype well developed. Genito-intestinal canal present on same side of body as ovary, joining intestinal caecum posterior to ovary. Uterus confined to area anterior to ovary holding one egg; egg 240 (224–256) long, 118 (106–130) wide. No intrauterine development of eggs observed ( Fig. 5 ).

Differential diagnosis

Indopolystoma elongatum is well characterized by its body size and shape. This species is much bigger and more elongated (body length 14,791 µm) than any other species of Indopolystoma , though there is an overlap of size values with I. indicum . Indopolystoma elongatum can be easily distinguished from the later by the number of intrauterine eggs. None of the specimens of I. elongatum have more than a single egg in utero while I. indicum has as many as 40.

Remarks: Zhangixalus arboreus hosts two polystomes, namely I. elongatum and I. rhacophori (see below), which is uncommon within anuran polystomes. However, Z. arboreus and Z. schlegelii occur sympatrically in Japan [ 1]. The possibility of a misidentification can thus not be excluded especially since molecular evidence on host identity is currently not available. We consider for now that both I. elongatum and I. rhacophori are separate species primarily on the basis of body length and haptor/total body length ratio (0.06 for I. elongatum vs. 0.18 for I. rhacophori ).

Figures

Figure 5. Indopolystoma elongatum n. gen. n. sp. from Zhangixalus arboreus. Ventral view of holotype. (A) A drawing; (B) A photograph. Scale bar: 1 mm.

Figure 6. Indopolystoma elongatum n. gen. n. sp. from Zhangixalus arboreus. Hamuli and marginal hooklets from holotype and paratypes. (A–A’) Holotype; (A’’–A’’’) Paratypes; (B) Marginal hooklet C1; (B’) Marginal hooklet C3; (B’’) Marginal hooklet C8. Scale bar: 100 µm (A–A’’’), 20 µm (B–B’’).