New and Already Known Acanthocephalans from Amphibians and Reptiles in Vietnam, with Keys to Species of Pseudoacanthocephalus Petrochenko, 1956 (Echinorhynchidae) and Sphaerechinorhynchus Johnston and Deland, 1929 (Plagiorhynchidae)

Abstract

Adults of 2 new species in 2 orders of acanthocephalans obtained from the intestines of terrestrial amphibians and reptiles collected between 1998 and 2004 in Vietnam are described here. Pseudoacanthocephalus nguyenthileae n. sp. (Palaeacnthocephala: Echinorhynchidae) was collected from 5 species of terrestrial amphibians: (1) the common Sunda toad Bufo melanostictus Schneider (Bufonidae); (2) Paa verucospinosa (Bourret); (3) Gunther's Amoy frog Rana guentheri Boulenger; (4) Taipei frog R. taipehensis Denburgh (Ranidae), and (5) the Burmese whipping frog Polypedates mutus (Smith) (Racophoridae); as well as from the Chinese cobra Naja atra Cantor (Reptilia: Elapidae) and house gecko Hemidactylus frenatus Dumeril and Bibron (Reptilia: Gekkonidae). Sphaerechinorhynchus maximesospinus n. sp. (Plagiorhynchidae: Sphaerechinorhynchinae) was isolated from a king cobra Ophiophagus hannah (cantor) (Reptilia: Elapidae). Cystacanths of Porrorchis houdemeri (Joyeux and Baer, 1935) Schmidt and Kuntz, 1967 (Plagiorhynchidae: Porrorchinae) obtained from the mesenteries of banded krait Bungarus fasciatus (Schneider) (Reptilia: Elapidae), a paratenic host, are reported for the first time. Keys to the species of Pseudoacanthocephalus and Sphaerechinorhynchus are included. Characteristic features distinguishing the new species from related taxa include: P. nguyenthileae has 15-19 (usually 16-18) proboscis hook rows, each with 5-6 hooks that progressively increase in length and size posteriorly. The largest, intermediate, and smallest proboscis hooks of S. maximesospinus are the middle, anterior, and posterior hooks, respectively; the proboscis and neck are enclosed in a membrane. Morphometric characteristics of P. nguyenthileae show host-related variability.

Acanthocephala from Amphibians in China with the Description of a New Species of Pseudoacanthocephalus (Echinorhynchida)

“…Southwell and Macfie (1925) reported 4 specimens from the intestine of a single toad captured in Hong Kong without indicating the host species. Van Cleave (1937) described Acanthocephocephalus sinensis, now widely regarded as a synonym (Amin, 1985;Golvan, 1994) of P. bufonis, based on specimens collected by E. C. Faust in central China during the period from 1920 to 1925. Otherwise there is little previous information published regarding this species in China.…”

“…As Petrochenko (1956) was referencing these specimens when he assigned P. bufonis as the type species, Pseudoacanthocephalus breviprostatus Kennedy, 1982, should replace P. bufonis as the type species of Pseudoacanthocephalus for systematists who concur that P. bufonis and P. breviprostatus constitute distinct species. Because Petrochenko's transfer of Shipley's E. bufonis was an explicit nomenclatural act, even if fortuitous, Amin (1985) properly listed the name as Pseudoacanthocephalus bufonis (Shipley, 1903) Petrochenko, 1956, regardless of its status as type species of the genus. .0/1 -Fejervarya limnocharis (Gravenhorst, 1829) .1/6 (17) 3.0 Hoplobatrachus rugulosus (Wiegmann, 1834) .0/1 -Limnonectes kuhlii (Tschudi, 1838) .1/6 (17) 20.0 Odorrana chloronata (Gü nther, 1876) .0/1 -Odorrana versabilis (Liu and Hu, 1962) .0/6 -Ophryophryne microstoma Boulenger, 1903 .0/2 -Philautus odontotarsus Ye and Fei in Ye et al, 1993 .1/1 (100) .1/3 (33) 3.0 Rana margaretae Liu, 1950 .0/7 -Rana wuchuanensis Xu in Wu et al, 1983 .0/1 -Subtotal .9/28 (32) .…”

“…The hooks of P. reesei, however, are much longer than has been reported for these other 3 species and apparently for any other species of the genus. Additionally, P. reesei is distinguished because it and Pseudoacanthocephalus nguyenthileae Amin, Ha, and Heckmann, 2008, are the only species of the genus in which proboscis hooks increase progressively in length from anterior to posterior positions. Besides having fewer longitudinal rows of fewer, but longer, hooks than P. nguyenthileae, males of P. reesei possess the typical 6 cement glands rather than 8 as reported (Amin et al, 2008) for P. nguyenthileae.…”

“…Although Golvan (1969) stated that the 2 genera could be differentiated clearly, Schmidt (1971) questioned the validity of these generic characters, and the issue was readdressed by Smales (2005). Golvan (1994) continued to recognize Pseudoacanthocephalus as did Amin et al (2008), who gave rationale for its validity. In addition to the characters defined by Petrochenko (1956) and Golvan (1969), and the more elongated tightly clustered cement glands (compacted so tightly as to be uncountable in the absence of dissection or cross sections) noted by Amin et al (2008), the 2 species collected in China appear to differ from Acanthocephalus by possession of a very thick body wall and in having the musculature of the outer wall of the proboscis receptacle arranged in irregular bands rather than the smooth sheath of Acanthocephalus.…”

“…Golvan (1994) continued to recognize Pseudoacanthocephalus as did Amin et al (2008), who gave rationale for its validity. In addition to the characters defined by Petrochenko (1956) and Golvan (1969), and the more elongated tightly clustered cement glands (compacted so tightly as to be uncountable in the absence of dissection or cross sections) noted by Amin et al (2008), the 2 species collected in China appear to differ from Acanthocephalus by possession of a very thick body wall and in having the musculature of the outer wall of the proboscis receptacle arranged in irregular bands rather than the smooth sheath of Acanthocephalus. Species previously assigned (Golvan, 1994;Amin et al, 2008) to Pseudoacanthocephalus and P. reesei, described here, constitute a readily recognized group of distinctive species.…”