First finding of Ityogonimus lorum and I. ocreatus co-infection in the Iberian mole, Talpa occidentalis

The Ityogonimus lorum-I. ocreatus co-infection is reported for the first time in the Iberian mole Talpa occidentalis in Asturias (NW Spain). Both Ityogonimus species are stenoxenous helminths of insectivores of the genus Talpa and they have often been found parasitizing the Iberian mole and also the European mole T. europaea, but a mixed infection had not been previously reported. The present study also highlights the main differential morphometric characteristics between I. lorum and I. ocreatus such as the body length, the ventral sucker diameter, the ratio between suckers and the distance between suckers.

The Iberian mole, Talpa occidentalis Cabrera, 1907 (Eulipotyphla: Talpidae) is a hypogean insectivore endemic to the Iberian Peninsula that is widely distributed in this region, except for north-eastern Spain (Román 2007). The parasitic helminth fauna of T.
Regarding the Italian mole, T. romana, Milazzo et al. (2002) analysed its parasite community in Southern Italy and they found six helminth species, with the presence of only one digenean, I. ocreatus.
Previous studies on the parasitic helminth fauna of the Iberian mole were carried out by Casanova (1993) and Casanova et al. (1996), who found only three digeneans (I. lorum, I. ocreatus and O. flexuosa). The prevalences of Ityogonimus spp. were 11.0% for I. lorum and 1.9% for I. ocreatus, and a co-infection of both brachylaimids was never found by these authors. In this sense, Frankland (1959) and Casanova (1993) hypothesised about an apparent negative interaction between I. lorum and I. ocreatus at the level of the individual host, since both European moles and Iberian moles parasitized by Ityogonimus harboured exclusively one of the species.
Here we report for the first time the co-infection of I. lorum and I. ocreatus in the Iberian mole T. occidentalis in Asturias (NW Spain). Moreover, the present finding constitutes the first record of mixed infections of Ityogonimus spp. not only in the Iberian mole, but also for the genus Talpa.
The present study was based on six Iberian moles trapped accidentally during a vole pest control campaign in four localities of Asturias (Spain): Coceña (3 specimens), Oles (1), Priesca (1) and Vegadali (1). After host necropsies, the recovered live digeneans were fixed between slides and coverslips with Bouin and posteriorly rinsed in 70º ethanol.
Then, specimens were stained with Semichon carmine, differentiated with 50% acid alcohol solution, dehydrated in an ethanol series (80º, 90º, 96º) and isopropyl alcohol, cleared with clove oil, and finally mounted on slides with Canada balsam (Figs. 1A and  B). Measurements of both gravid Ityogonimus species are shown in Table 1 in order to establish the differential characters for specific classification.
In this study, I. lorum-I. ocreatus co-infection was detected in two of the six studied hosts (33.3%). In these two moles the individual intensities of each brachylaimid were: 18 I. lorum + 7 I. ocreatus and 4 I. lorum + 13 I. ocreatus. On the other hand, in the whole sample, prevalences of I. lorum and I. ocreatus were respectively 50% and 83.3% (see Table 2).
Within the Brachylaimidae, the genus Ityogonimus belongs to the subfamily Ityogoniminae, which also includes the genus Scaphiostomum. Species of Ityogonimus are distinguished by their reduced suckers and by the presence of a short oesophagus (Pojmańska, 2002). Both I. lorum and I. ocreatus are filiform digeneans with two small suckers clearly separated from each other. This is the most evident difference when comparing to Scaphiostomum species, which presents oral and ventral suckers close together. In all Ityogonimus specimens, the prepharynx and the oesophagus are very reduced whereas the pharynx is well-developed. The two caeca extend up to the posterior end of the body. Gonads are situated near the posterior extremity. Testes are well separated and the ovary is located between them. Both ovary and testes are intracaecal and sub-spherical to oval in shape. The two testes are disposed in tandem. The genital pore is localised between the ovary and the posterior testis, at the anterior level of the posterior testis. The vitellarium is formed by two lateral and extracaecal vitelline fields that extend from the ventral sucker to the level of the anterior testis ( Fig. 1A and B). The main morphometric differences between I. lorum and I. ocreatus are: (i) the body length (4.18 mm vs 15.02 mm), (ii) the ventral sucker diameter (432 µm vs 106 µm), (iii) the ratio between suckers (OS/VS) (0.81 vs 3.48), and (iv) the distance between suckers (976 µm vs 3,846 µm) (see Table 1).