Redescription of Heligmosomoides neopolygyrus,
Asakawa and Ohbayashi, 1986 (Nematoda:
Heligmosomidae) from a Chinese Rodent, Apodemus
peninsulae (Rodentia: Muridae); with comments on
Heligmosomoides polygyrus polygyrus (Dujardin, 1845)
and related species in China and Japan

J. Massoni, M.C. Durette-Desset, J.P. Quéré, F. Audebert

► To cite this version:

J. Massoni, M.C. Durette-Desset, J.P. Quéré, F. Audebert. Redescription of Heligmosomoides neopolygyrus, Asakawa and Ohbayashi, 1986 (Nematoda: Heligmosomidae) from a Chinese Rodent, Apodemus peninsulae (Rodentia: Muridae); with comments on Heligmosomoides polygyrus polygyrus (Dujardin, 1845) and related species in China and Japan. Parasite, 2012, 19 (4), pp.367-374. 10.1051/parasite/2012194367. hal-02891023

HAL Id: hal-02891023

https://hal.sorbonne-universite.fr/hal-02891023

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REDESCRIPTION OF *HELIGMOSOMOIDES NEOPOLYGYRUS*, ASAKAWA AND OHBAYASHI, 1986
(NEMATODA: HELIGMOSOMIDAE) FROM A CHINESE RODENT, APODEMUS PENINSULAE
(RODENTIA: MURIDAE); WITH COMMENTS ON HELIGMOSOMOIDES POLYGYRUS POLYGYRUS
(DUJARDIN, 1845) AND RELATED SPECIES IN CHINA AND JAPAN

MASSONI J.*,**, DURETTE-DESSET M.C.***, QUÉRÉ J.P.**** & AUDEBERT F.*

**Summary:**

Heligmosomoides neopolygyrus, Asakawa and Ohbayashi, 1986 (Nematoda, Heligmosomoidea) is redescribed from *Apodemus peninsulae* from Rangtang, Sichuan, China. A morphological review of the *Heligmosomoides* spp. belonging to the "*polygyrus* line" proposed by Asakawa (1988) is made using new characters. This enabled us to distinguish two subspecies in *Mus musculus* (*Heligmosomoides polygyrus* bakeri from Japan and *H. p. polygyrus* from China) and two valid species in *Apodemus* spp. (*H. neopolygyrus* from Japan [in *A. peninsulae*] and from China [in *A. agrarius*] and *H. asakawae* from China [in *A. uralensis*]). Three parasite species of *A. agrarius* and *A. peninsulae*, previously identified by Asakawa et al. (1993) as *H. neopolygyrus*, are considered to be *Heligmosomoides incertae sedis*. This is the first report of *H. neopolygyrus* in *A. peninsulae* from China.

**KEY WORDS:** Heligmosomoides spp., Nematoda, Trichostrongylina, Heligmosomoidea, Rodent, Muridae, China, Japan, taxonomy.

**Résumé** : REDESCRIPTION D'HELIGMOSOMOIDES NEOPOLYGYRUS, ASAKAWA ET OHBAYASHI, 1986 (NEMATODA : HELIGMOSOMIDAE) CHEZ UN RONGEUR DE CHINE, APODEMUS PENINSULAE (RODENTIA : MURIDAE) ; ET COMMENTAIRES SUR HELIGMOSOMOIDES POLYGYRUS POLYGYRUS (DUJARDIN, 1845) ET LES ESPÈCES SIGNALÉES EN CHINE ET AU JAPON

Heligmosomoides neopolygyrus, Asakawa et Ohbayashi, 1986 (Nematoda: Heligmosomoidea) parasite d'Apodemus agrarius au Japon est redécrit chez un *A. peninsulae* originaire de Chine. Une revue des espèces du genre Heligmosomoides spp. appartenant à la lignée "polygyrus" caractérisée par Asakawa (1988) est faite en utilisant de nouveaux caractères. Ceci nous a permis de confirmer la distinction de deux sous-espèces chez Mus musculus (Heligmosomoides polygyrus bakeri au Japon et *H. p. polygyrus* en Chine) et de deux espèces valides chez *Apodemus* spp. [*H. neopolygyrus* au Japon (chez *A. peninsulae*) et en Chine (chez *A. agrarius*) et *H. asakawae* en Chine (chez *A. uralensis*)]. Trois espèces parasites d'A. agrarius et d'A. peninsulae qui ont été identifiées par Asakawa et al. (1993) comme *H. neopolygyrus* sont considérées comme des Heligmosomoides incertae sedis. C'est la première fois qu'H. neopolygyrus est signalé chez un *A. peninsulae* en Chine.

**MOTS-CLÉS** : Heligmosomoides spp., Nematoda, Trichostrongylina, Heligmosomoidea, Rongeur, Muridae, Chine, Japon, taxinomie.

INTRODUCTION

The genus *Heligmosomoides* Hall, 1916 (Heligmosomidae) is widespread in the Holarctic region and is found mainly in the Arvicolina but also in the Murinae. Asakawa (1988) divided the species of the genus into five categories namely the “travassosi-douglasi line”, the “relic group”, the “laevis-carolinensis line”, the “longicirratum-longispiculatus line” and the “polygyrus line”. The last line parasitizes only *Mus* and *Apodemus*. Until now, three

species belonging to this line have been described or recorded from China: *Heligmosomoides polygyrus* *polygyrus* (Dujardin, 1845); *H. neopolygyrus* Asakawa and Ohbayashi, 1986 and *H. asakawae* Tenora and Barus, 2001, (Asakawa et al., 1990, 1992, 1993). *H. neopolygyrus* and *H. p. bakeri* Durette-Desset et al., 1972 are present in Japan (Asakawa & Ohbayashi, 1986; Hasegawa et al., 1983).

In this study we redescribe *H. neopolygyrus* from Sichuan Province (central China) in *Apodemus peninsulae* (Muridae). The use of new morphological characters on the present and previously published material allows us to examine the validity of some reports of the "*polygyrus* line" described as *H. neopolygyrus*, as well as the distribution of the genus *Heligmosomoides* in Chinese and Japanese Muridae.

MATERIALS AND METHODS

Rodent hosts were collected in June 2004, as part of a French-British-Chinese program, for which the main goals were the screening of human populations for alveolar echinococcosis and the study

<footnote>* Université Pierre et Marie Curie, Paris, UMR 7207 CNRS-MNHN-UPMC "Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements – CR2P". MNHN, 57, rue Cuvier, CC 48, 75231 Paris Cedex 05, France.</footnote>

<footnote>** Université Paris-Sud, UMR 8079 CNRS-UPSUD Écologie Systématique et Évolution, Équipe Biodiversité, Systématique et Évolution, Bâtiment 360, 91405 Orsay Cedex, France.</footnote>

<footnote>*** Département de Systématique et Évolution, Muséum national d'Histoire naturelle, UMR 7138 CNRS-MNHN-UPMC, 57, rue Cuvier, CC 52, 75231 Paris Cedex 05, France.</footnote>

<footnote>**** INRA, UMR 1062 CBGP, Campus international de Baillarguet, CS 30016, 34988 Montferrier-sur-Lez Cedex, France.</footnote>

<footnote>Correspondence: Fabienne Audebert.</footnote>

<footnote>Tel.: 33 (0)1 40 79 80 58.</footnote>

<footnote>E-mail: fabienne.audebert@upmc.fr</footnote>
of its transmission. The study area was located in Rangtang, Sichuan, China. The rodents were weighed and dissected in the field to determine the sex and reproductive status. Heads and tissue samples (or the whole body for a few specimens) were preserved for identification (Courant *et al.*, 1999). The nomenclature of the rodents follows Wilson & Reeder (2005).

The material studied here came from a single specimen of *A. peninsulae* (Thomas, 1907). The small intestine was preserved in 5 % formalin and transported to the Museum national d'Histoire naturelle (MNHN) in Paris, France, one month after collection. It was then transferred to 70 % ethanol. To determine the precise intestinal location of the parasites, the small intestine (SI) was divided longitudinally into four equivalent sections (SI 1 to SI 4) numbered from the pylorus to the caecum. Nematodes were collected from each section and stored in 70 % ethanol. They were examined as temporary mounts in lactophenol. The synlophe was studied following the method of Durette-Desset (1985) and the axis of orientation following that of Durette-Desset & Digiani (2005). The total number of cuticular ridges reported, is followed by the number of dorsal ridges and the number of ventral ridges in parentheses. The ridges were numbered from left to right, from 1 to n on the dorsal side, and from 1' to n' on the ventral side. The nomenclature used for the study of the caudal bursa follows Durette-Desset & Chabaud (1981) and Durette-Desset & Digiani (2012). The nomenclature for the parasites used above the family group follows Durette-Desset & Chabaud (1993). Measurements are given in micrometers, unless otherwise stated. Specimens studied have been deposited in the Helminthological Collection of the MNHN.

## RESULTS

HELIGMOSOMOIDES NEOPOLYGYRUS ASAKAWA AND
OHBAYASHI, 1986

Material: 88 females and 84 males, MNHN 442MQ. Material studied: 13 males and ten females

Host: *Apodemus peninsulae* (Thomas, 1907) (Rodentia: Muridae: Murinae).

Site in host: all specimens were found in SI 1.

Geographic origin: Rangtang, Sichuan, China. J.P. Coll.: Quéré, June 2004.

* Redescription (Figs 1-16)

Small nematode coiled along ventral side having two to four sinistral spirals in males and four to eight in females. Deirids setiform, situated at level of excretory pore (Fig. 4), observed in one male and one female.

Synlophe (studied in seven males and three females): in both sexes the cuticle bears longitudinal, continuous ridges without struts. Five ridges appear posterior to cephalic vesicle (Figs 2, 3, 5, 6), other ridges appear at different levels between cephalic vesicle and excretory pore; roughly equivalent numbers on dorsal and ventral sides (Figs 3, 5). Ridges disappear at about 130 anterior to caudal bursa in male, 110 anterior to caudal extremity in females. Number of ridges: at level of esophago-intestinal junction; 23, 26 (13D/13V see Fig. 7) in two males, 25, 26 (13D/13V, see Fig. 10) in two females; at mid-body, 24-27 (13D/13V, see Fig. 8) in seven males, 24-26 (13D/11V, see Fig. 11) in three females; within distal fifth, 25-27 (12D/14V, see Fig. 9) in three males, 25-31 (13D/14V, see Fig. 12) in three females. Left ventral ridges slightly larger than the other ridges. Axis of orientation sub-frontal directed from right to left (Figs 7-12).

Male: caudal bursa dissymmetrical with right lobe larger than left lobe (Fig. 14). Prebursal papillae well developed (Fig. 14). Caudal bursa pattern of type 2-3, for both lobes. Rays 3 thicker and longer than rays 2. In both lobes, rays 6, arising first from common trunk of rays 4-6. Rays 6 parallel to rays 8 and very close to them (Fig. 14). Rays 8, of similar length, arising at base of common trunk of rays 2-6. Extremities of rays 8 curved dorsally. Dorsal ray very small divided within distal third into two branches, each branch divided into two twigs, rays 9 (external branches) slightly shorter than rays 10 (internal branches) (Fig. 13). Rays 9 and 10 arising at same level as division of dorsal ray. Spicules poorly sclerotised, subequal, ending in sharp tip (Fig. 15). Gubernaculum absent. Genital cone, bearing two long papillae 7 on dorsal lip (Fig. 14). Papilla zero not observed. Measurements of 13 males are listed in Table 1.

Female: monodelphic. Vestibule very long. Tail rounded with caudal spine (Fig. 16). Measurements of ten females are listed in Table I.

* Differential diagnosis

The specimens described above belong to the genus *Heligmosomoides* Hall, 1916 (Heligmosomoidea: Heligmosomidae), as redefined by Durette-Desset (1968), which is characterized mainly by longitudinal cuticular ridges, a poorly developed dorsal ray, a very long vestibule and long deirids. Asakawa (1988) divided the genus into five categories one of which was the "*polygyrus* line". This line was proposed for *Heligmosomoides* parasitic only in Muridae (*Mus* and *Apodemus*) and is made up of *H. neopolygyrus* Asakawa and Ohbayashi, 1986 in *A. peninsulae* from Japan and three subspecies of *Heligmosomoides polygyrus*: *H. p. polygyrus* (Dujardin, 1845) in *Apodemus* spp. and rarely in *Mus musculus* from the Palearctic region (Eurasia,
<figure><img src="image_2.png" /><figcaption>Figs 1-16. – *Heligmosomoides neopolygyrus* Asakawa and Ohbayashi, 1986, in *Apodemus peninsulae*, from China: 1-6, male, anterior extremity, 1, right lateral view, 2-3, origin of cuticular ridges, 2, dorsal view, 3, right lateral view, 4, detail of excretory pore and deirids, ventral view, 5-6, origin of cuticular ridges, 5, left lateral view, 6, sub-ventral view; 7-12, transverse sections of body, 7-9, male, 7, at level of esophago-intestinal junction, 8, at mid-body, 9, within distal fifth, 10-12, female, 10, at level of esophago-intestinal junction, 11, at mid-body, 12, within distal fifth; 13-15, male, 13, dorsal ray with rays 9 and 10, ventral view, 14, caudal bursa, ventral view, 15, spicules, *in situ*, ventral view; 16, female, posterior extremity, right lateral view.</figcaption></figure>

Scale bar: Figs 1-3, 5-6, 14, 16: 100 µm. Figs 4, 7-12, 15: 50 µm. Fig. 13: 20 µm. Abbreviations: de: deirids, r: right side, d: dorsal side, d.r.: dorsal ray, p.7: papillae 7. Transverse sections are oriented and numbered as in Fig. 7.
<table><caption>Table I. – Comparison between measurements (µm) of *Heligmosomoides neopolygyrus* from *Apodemus peninsulae* in Japan (Asakawa & Ohbayashi, 1986) and from China (this article).</caption><thead><tr><th></th><th></th><th>Asakawa and Ohbayashi, 1986<br>Min-Max</th><th>This article<br>Min-Max</th></tr></thead><tbody><tr><td rowspan="15">Male</td><td>Number of specimens observed</td><td>5</td><td>13</td></tr><tr><td>Total length</td><td>7,600-10,000</td><td>4,625-6,400</td></tr><tr><td>Maximum width</td><td>150-200</td><td>80-100</td></tr><tr><td>Length of cephalic vesicle</td><td>54-83</td><td>40-65</td></tr><tr><td>Width of cephalic vesicle</td><td>37-56</td><td>30-40</td></tr><tr><td>Distance from nerve ring to anterior extremity</td><td>188-223</td><td>130-170</td></tr><tr><td>Distance from derids to anterior extremity</td><td>not observed</td><td>210</td></tr><tr><td>Distance from excretory pore to anterior extremity</td><td>254-464</td><td>195-390</td></tr><tr><td>Length of esophagus</td><td>557-636</td><td>465-650</td></tr><tr><td>Ratio esophagus / total length</td><td>6 to 7 %</td><td>7 to 12 %</td></tr><tr><td>Length of right spicule</td><td>510-640</td><td>370-620</td></tr><tr><td>Length of left spicule</td><td>510-640</td><td>370-620</td></tr><tr><td>Ratio spicule length/ Total length</td><td>6 to 7 %</td><td>7 to 12 %</td></tr><tr><td>Gubernaculum</td><td>no data</td><td>absent</td></tr><tr><td>Number of ridges at midbody</td><td>28-35</td><td>24-27</td></tr><tr><td rowspan="15">Female</td><td>Number of specimens observed</td><td>5</td><td>10</td></tr><tr><td>Total length</td><td>17,500-27,300</td><td>9,600-11,500</td></tr><tr><td>Maximum width</td><td>150-320</td><td>70-150</td></tr><tr><td>Length of cephalic vesicle</td><td>51-76</td><td>45-60</td></tr><tr><td>Width of cephalic vesicle</td><td>48-60</td><td>35-40</td></tr><tr><td>Distance from nerve ring to anterior extremity</td><td>127-191</td><td>115-170</td></tr><tr><td>Distance from derids to anterior extremity</td><td>n.o.</td><td>230</td></tr><tr><td>Distance from excretory pore to anterior extremity</td><td>239-347</td><td>210-300</td></tr><tr><td>Length of esophagus</td><td>378-576</td><td>530-685</td></tr><tr><td>Ratio esophagus / Total length</td><td>2 %</td><td>3 to 7 %</td></tr><tr><td>Length of caudal tip</td><td>no data</td><td>3-20</td></tr><tr><td>Length of vagina vera</td><td>no data</td><td>12-25</td></tr><tr><td>Length of tail</td><td>108-118</td><td>70-115</td></tr><tr><td>Distance from vulvar opening to tail</td><td>315-410</td><td>230-330</td></tr><tr><td rowspan="5">Genital branch</td><td>Length of vestibule</td><td>no data</td><td>385-570</td></tr><tr><td>Length of sphincter</td><td>no data</td><td>40-60</td></tr><tr><td>Width of sphincter</td><td>no data</td><td>30-50</td></tr><tr><td>Length of infundibulum</td><td>no data</td><td>130-240</td></tr><tr><td>Length of uterine branch</td><td>no data</td><td>1,170-2,370</td></tr><tr><td rowspan="5">Eggs</td><td>Ratio uterus/ Total length</td><td>no data</td><td>10 to 22 %</td></tr><tr><td>Number of eggs</td><td>no data</td><td>8-45</td></tr><tr><td>Length of eggs</td><td>76-87</td><td>50-75</td></tr><tr><td>Width of eggs</td><td>54-60</td><td>30-50</td></tr><tr><td>Number of ridges at midbody</td><td>29-33</td><td>25-26</td></tr></tbody></table>

<table><caption>Table II. – Morphological characters of which the four in columns 3 (a, b), 4, 5, 6 differentiate the five species of *Heligmosomoides* belonging to the “polygyrus line” defined by Asakawa, 1988.</caption><thead><tr><th rowspan="3">Species</th><th rowspan="3">Asakawa &<br>Ohbayashi<br>(1986)<br>Swelling<br>on 8 rays</th><th colspan="4">This article</th></tr><tr><th colspan="2">Arisal of rays 6 compared to the arisal<br>of rays 4 and 5 on their common trunk</th><th rowspan="2">Rays 6 //<br>to rays 8</th><th rowspan="2">Direction of<br>extremities of<br>rays 6</th><th rowspan="2">Comparative length<br>of rays 9 and 10</th></tr><tr><th>Right lobe</th><th>Left lobe</th></tr></thead><tbody><tr><td>Heligmosomoides<br>p. polygyrus</td><td>present</td><td>proximally</td><td>proximally<br>or at same level</td><td>absent</td><td>curved<br>to dorsal ray</td><td>9 shorter 10</td></tr><tr><td>Heligmosomoides<br>p. bakeri</td><td>present</td><td>proximally</td><td>proximally</td><td>absent</td><td>curved<br>to dorsal ray</td><td>9 shorter 10</td></tr><tr><td>Heligmosomoides<br>p. corsicus</td><td>present</td><td>proximally<br>or at same level</td><td>proximally</td><td>absent</td><td>curved<br>to dorsal ray</td><td>9 shorter 10</td></tr><tr><td>Heligmosomoides<br>asakawae</td><td>present</td><td>distally</td><td>distally</td><td>absent</td><td>curved<br>to rays 5</td><td>left 9 as similar size as 10;<br>right 9 longer than ray 10</td></tr><tr><td>Heligmosomoides<br>neopolygyrus</td><td>absent</td><td>proximally</td><td>proximally</td><td>present</td><td>curved<br>to rays 5</td><td>9 shorter than 10<br>or 9 as similar size as 10</td></tr></tbody></table>
Japan); *H. p. corsicus* Durette-Desset, 1968, in *M. musculus* from Corsica; and *H. p. bakeri* Durette-Desset *et al.*, 1972, in *M. musculus* from North America and from Japan (Hasegawa *et al.*, 1983; Yokoyama *et al.*, 1985). The "polygyrus line" was differentiated from the other lines by very short spicules, small ridges, without a prominent size gradient and very narrow intervals between the ridges (Asakawa, 1988). In this line, *H. neopolygyrus* is distinguished only by the absence of a swelling at the base of the externo-dorsal rays (rays 8) (Asakawa & Ohbayashi, 1986). Tenora & Barus (2001) raised the three subspecies of *H. p. polygyrus*, *H. p. bakeri* and *H. p. corsicus* to the species level. Cable *et al.* (2006) confirmed the specific status of *H. polygyrus* and *H. bakeri* using internal transcribed spacer (ITS) but Maizels *et al.* (2011) contested this result using another gene (CO1). Thus, the taxonomic ranks of *H. polygyrus* and *H. bakeri* are still the focus of discussion and in this article we follow the morphological study of Durette-Desset *et al.* (1972) are performed until further molecular studies on this subject.

Tenora & Barus (2001) considered the specimens described by Asakawa *et al.* (1992) as *H. p. polygyrus* in *Apodemus uralensis* (= *A. microps*) from China (Ulumuchi = Urumqi) to represent a new species and named it *H. asakawae*. They differentiated it from *H. p. polygyrus* by only one character, the "morphology of medio-dorsal ray". Tenora *et al.* (2003) wrote "the dorsal rib of male differs distinctly morphologically from that of the species *H. p. polygyrus*". From the drawing of Asakawa *et al.* (1992), we interpreted this character as the relative length of rays 9 and 10. In *H. p. polygyrus*, rays 9 are markedly shorter than rays 10, in *H. asakawae*, left ray 9 is as long as left ray 10 and right ray 9 is longer than right ray 10 (Table II).

The Chinese specimens have the characters of the "polygyrus line" and shared along with *H. neopolygyrus* the absence of a swelling at the base of the externo-dorsal ray. However, using only one character, the relative lengths of rays 9 and 10 for *H. asakawae* and the absence of the swelling at the base of rays 8 for *H. neopolygyrus*, to distinguish these species from *H. polygyrus sensu lato* seems to us insufficient to assure of their validity as species.

Using characters of the caudal bursa, the three subspecies of *H. polygyrus* share the same characters, whereas *H. asakawae* and *H. neopolygyrus* each have at least two other specific characters. In *H. asakawae*, rays 6 arise distally to the level of the divergence of rays 4 and 5. In *H. neopolygyrus*, rays 6 and rays 8 are close together and parallel. In addition, in *H. asakawae* and *H. neopolygyrus* the extremities of rays 6 are curved towards the extremities of rays 5 whereas in the three subspecies of *H. polygyrus* they are curved towards the dorsal ray (Table II).

The specimens described above have all the characters of *H. neopolygyrus* (Table II), but they can be differentiated by several elements from the type material described from Japan. Our specimens are about one third smaller, with smaller spicules but the spicule length/ body length ratio is larger (7-12 % versus 6-7 %); the ventral cuticular ridges are slightly larger than the dorsal ones; the number of ridges at midbody in the males is 24-27 versus 28-35 and in the females is 24-26 versus 29-33 (Table I).

Durette-Desset (1968) and Durette-Desset *et al.* (1972) demonstrated that in *H. polygyrus*, a differentiation exists that is defined only by a relatively higher number of cuticular ridges in the posterior part of the body for an equivalent length of the body. These ridges are more numerous in specimens from Corsica (*H. p. corsicus*) and North America (*H. p. bakeri*) than in those from Europe (*H. p. polygyrus*). This difference is also present in *H. p. polygyrus* and *H. p. bakeri* from China and Japan.

Unfortunately, the number of Japanese specimens, in Asakawa & Ohbayashi, (1986) (five males, five females) is too small to be conclusive unlike the work by Durette-Desset *et al.* (1972) where numerous specimens were observed. Therefore, we prefer at least temporarily, to identify the Chinese specimens as *H. neopolygyrus* without considering them as a subspecies.

## DISCUSSION

H. neopolygyrus was described for the first time by Asakawa & Ohbayashi (1986) in *A. peninsulae* in the Abashiri area of Hokkaido Island (Japan). Asakawa *et al.* (1990) recorded *H. neopolygyrus* in *A. agrarius* from China. In this work, only the dorsal ray and the base of rays 8 of one specimen collected in Shenyang were illustrated and showed that the swelling at the base of rays 8 was absent; a feature which is characteristic of *H. neopolygyrus*. For this reason, Asakawa *et al.* (1990) identified their specimens as *H. neopolygyrus*. In the same article, the authors reported finding *H. neopolygyrus* in *A. agrarius* from Kyonggi-do (Korean peninsula) but provided no description or illustrations. Asakawa (1991) confirmed the presence of *H. neopolygyrus* in *A. agrarius* from China and the Korean peninsula as well as in *A. peninsulae* from Japan.

Asakawa *et al.* (1992) reported *H. polygyrus* in *A. uralensis* (= *A. microps*) from Ulumuchi (China). However, this was, in fact, a new species later named *H. asakawae* by Tenora & Barus (2001).

Asakawa *et al.* (1993) studied the distribution of *H. neopolygyrus* in the east of China in *A. agrarius* and
<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

Figs 17-23. — Caudal bursae of *Heligmosomoides* spp., from China, ventral views: 17, 18, *H. p. polygyrus* in *Mus musculus*, 17, from Shenyang, 18, from Changchun; 19, 20, *H. neopolygyrus* in *Apodemus agrarius*, 19, from Shenyang, 20, from Changsha; 21-23, *Heligmosomoides incertae sedis*, 21, in *A. agrarius*, from Antu, 22, in *A. peninsulae*, from Liang-Cheng, 23, in *A. peninsulae*, from Hulin. After Asakawa *et al.* (1993) and modified.

Scale bar: Figs 17-23: 100 µm. Letters in brackets referred to Fig. 1 of Asakawa *et al.* (1993). Grey bars show level of divergence of rays 4 and 5 and arising of rays 6 on the common trunk of rays 4 to 6: Figs 17, 19, 20, 23, in both lobes rays 6 arise proximally to the level of divergence of rays 4 and 5; Fig. 18, in left lobe ray 6 arising proximally to the level of divergence of rays 4 and 5, in right lobe at same level as the divergence of rays 4 and 5; Fig. 21, in both lobes rays 6 arising slightly distally to the level of divergence of rays 4 and 5; Fig. 22, in both lobes, rays 6 arise at same level as the divergence of rays 4 and 5.
in *A. peninsulae*. Moreover, they compared the mor-
phological characteristics of rays 8 in *H. neopolygyrus*
and in *H. p. polygyrus* from China. Although this article
was in Japanese, the authors presented a map of
eastern China, in which they included seven illustra-
tions of caudal bursae in ventral view: two attributed
to *H. p. polygyrus* (Figs 17-18) and five attributed to *H.
neopolygyrus* (Figs 19-23) from the different provinces
and different hosts. No measurements were provided.
A detailed analysis of these caudal bursae using the
known criteria and the new criteria provided in this
study, allows us to conclude the recording of *H. neo-
polygyrus* in *A. peninsulae* by Asakawa *et al*. (1993)
as erroneous. The five caudal bursae identified as *H.
neopolygyrus* all clearly lacked the swelling at the base
of rays 8 which is characteristic of *H. polygyrus* and
differen-tiates it from *H. neopolygyrus*. However, these
species can be distinguished from each other by the
following features: (1) the relative distance between
rays 6 and 8; and (2) the level at which rays 6 arise
compared to the level of divergence of rays 4 and 5
on their common trunk. We consider that only the
caudal bursae of the specimens parasitic in *A. agrarius*
from Shenyang (Fig. 19) and Changsha (Fig. 20) may
be identified as *H. neopolygyrus* due to the absence
of swelling at the base of rays 8, with rays 6 arising
proximally to the level of divergence of rays 4 and
5, and with rays 6 and 8 being parallel and close to
each other.

In the other three specimens (Figs 21-23) rays 6 and
8 are distant from each other, which differentiates
them from *H. neopolygyrus*. In addition, in the caudal

bursa of the specimen from *A. agrarius* from Shenyang
(Fig. 21), rays 6 arise just slightly distally to the level
of divergence of rays 4 and 5 and in the one from
Liang-Cheng (Fig. 22), rays 4-6 diverge at same level in
both lobes. The specimen from Hulin (Fig. 23) is the
only one with rays 6 arising proximally to the level of
divergence of rays 4 and 5, as in *H. neopolygyrus*. In
the absence of other features, particularly those of the
synlophe, it is not possible to attribute a specific name
to these species and we consider them as *Heligmo-
somoides incertae sedis* belonging to the “*polygyrus*
line”. Considering as partially inaccurate identifications
of Asakawa *et al*. (1993), we report for the first time
the identification of *H. neopolygyrus* in *A. peninsulae*
in Sichuan (central China).

Asakawa & Ohbayashi (1986) suggested that further
studies may reveal the presence of *H. neopolygyrus*
in *A. peninsulae* from the Northeast Palearctic region.
This work supports a widespread distribution of *H.
neopolygyrus sensu lato* which seems to follow its
main host *A. peninsulae*. The presence of *H. neopoly-
gyrus* in *A. agrarius* in China has been reported twice
(Asakawa *et al.*, 1990, 1993) (Fig. 24).

Despite the discovery of new criteria to differentiate
the species of the “*polygyrus*” complex reported in
China and Japan, their systematic position remains
uncertain due to incomplete descriptions and does
not allow us to use certain potentially differentiating
characters such as the number of cuticular ridges in
the posterior part of the body. Both molecular and
morphological studies need to be undertaken to deter-
mine their systematic rank (species or subspecies).

<figure><img src="image_10.png" /><figcaption>Fig. 24. – Distribution of the species of the genus *Heligmosomoides*, belonging to the “*polygyrus* line” modified from Asakawa (1988) from China and Japan.</figcaption></figure>
ACKNOWLEDGEMENTS

The research of alveolar echinococcosis in China was supported by Grant Number RO1 TW001565 from the Fogarty International Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Fogarty International Center or the National Institutes of Health. Those programs have been coordinated by Patrick Giraudoux and Francis Raoul, University of Franche-Comté. The authors thank Dr M. Asakawa for reprints of his articles that were necessary for this study and Dr K. Liittschwager for reviewing the English text (USA).

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Received on April 5th, 2012

Accepted on June 6th, 2012