Heligmostrongylus sp.

Panti-May, Jesús Alonso, Moguel-Chin, Wilson Isaias, Hernández-Mena, David Iván, Cárdenas-Vargas, Miguel Humberto, Torres-Castro, Marco, García-Prieto, Luis, Digiani, Maria Celina, Hernández-Betancourt, Silvia F. & Vidal-Martínez, Víctor Manuel, 2023, Helminths of small rodents (Heteromyidae and Cricetidae) in the Yucatan Peninsula, Mexico: an integrative taxonomic approach to their inventory, Zootaxa 5357 (2), pp. 205-240 : 220-221

Heligmostrongylus sp.

Site of infection: Small intestine

Host species: Peromyscus yucatanicus and Ototylomys phyllotis

Locality: Santa Cruz cattle ranch, Vallazoo (Yucatan) and Balam Nah eco-hotel (Quintana Roo)

Specimens deposited: CNHE 12022

GenBank accession numbers: OR271675, OR271676

Comments: The specimens found in the Yucatan Peninsula belong to the genus Heligmostrongylus according to the features described by Durette-Desset et al. (2017), i.e., synlophe with 10‒14 ridges; careen made up of two large continuous ridges and other ridges discontinuous or scalloped; single axis of orientation subfrontal; bursal pattern of type 2-2-1; dorsal ray dividing generally within proximal half; gubernaculum absent; spicules ending in a single sharp tip. Our specimens had a synlophe with 13 ridges; a well-developed careen made up of two ridges plus 11 interrupted, scalloped ridges, arranged in linear series (five dorsal and six ventral) ( Figure 4J ), single axis of orientation subfrontal; bursal pattern of type 2-2-1, dorsal ray dividing within proximal third, rays 9 long, slightly hook-shaped, crossing over rays 8 ventrally, gubernaculum absent ( Figure 4K ); and spicules 570–620 long.

Following the keys of Durette-Desset et al. (2017) the genus Heligmostrongylus includes nine species reported from the Cuniculidae , Echimyidae and Dasyproctidae in South America: Heligmostrongylus almeidai (Durette-Desset & Tchéprakoff) in Brazil, Heligmostrongylus chiarae Durette-Desset, Deharo, Santiváñez-Galarza & Chabaud in Bolivia, Heligmostrongylus crucifer (Travassos) in Brazil, Heligmostrongylus differens Lent & Freitas in Brazil, Heligmostrongylus echimyos Diaw in French Guiana, Heligmostrongylus elegans (Travassos) in Brazil, Heligmostrongylus proechimysi Durette-Desset in Colombia, Heligmostrongylus sedecimradiatus (Linstow) in Brazil, and Heligmostrongylus squamastrongylus (Travassos) in Brazil. Our specimens differ from He. almeidai, He. chiarea, He. elegans, He. echimyos, He. proechimysi, He. sedecimradiatus , and He. squamastrongylus by having rays 9 crossing over rays 8 (in these seven species rays 9 do not touch rays 8). In the case of He. differens and He. crucifer , differences in the pattern of rays 9 can be observed. Heligmostrongylus crucifer has rays 9 oriented to the dorsal lobe of bursa and He. differens has rays 9 smaller than rays 10, whereas our specimens have slightly curved rays 9, oriented to the lateral lobes and as long as rays 10. In addition, He. crucifer has 12 ridges in both sexes and He. differens possesses spicular alae developed. Based on these differences, the specimens from Mexico may represent a species not described yet.

This is the first record of Heligmostrongylus in North American rodents and for representatives of the Cricetidae .

Figures

FIGURE 4. A. Posterior end of male specimen of Trichuris silviae from Heteromys gaumeri showing the slightly campanulate spicular sheath (arrow), lateral view. B. SEM micrograph of the anterior extremity of Monodontus sp. from Sigmodon toltecus showing the mouth opening, paired cutting plates and cervical papillae (arrow), ventral view. C. Cross section at midbody showing features of the synlophe of female Vexillata vexillata from Heteromys gaumeri. D. Male caudal bursa of Vexillata vexillata from Heteromys gaumeri, ventral view. E. Cross section at midbody showing features of the synlophe of male Heligmosomoidea gen. sp. cf. Vexillata from Ototylomys phyllotis. F. Cross section at midbody showing features of the synlophe of female Carolinensis sp. from Peromyscus yucatanicus. G. Cross section at midbody showing features of the synlophe of male Hassalstrongylus aduncus from Sigmodon toltecus. H. Cross section at midbody showing features of the synlophe of female Hassalstrongylus musculi from Oligoryzomys fulvescens. I. Male caudal bursa of Hassalstrongylus musculi from Ototylomys phyllotis, dorsal view. J. SEM micrograph of female Heligmostrongylus sp. from Peromyscus yucatanicus showing the discontinuous ridges, lateral view. K. Male caudal bursa of Heligmostrongylus sp. from Peromyscus yucatanicus, ventral view. L. Cross section at midbody of female Heligmonellidae gen. sp. from Sigmodon toltecus showing the absence of synlophe. Abbreviations: r, right side; v, ventral side. All cross sections of the synlophe orientated as in figure C.