Morphometric and Molecular Analyses of Ostertagia leptospicularis Assadov, 1953 from Ruminants: Species Diversity or Host Influence?

Abstract

Ostertagia leptospicularis Assadov, 1953 was formally described in roe deer Capreolus capreolus and has been reported in a wide range of ruminants, including other Cervidae, as well as Bovidae. Nematode specimens derived from various host species exhibit morphological similarity; however, some differences can be observed. It is unclear if this is due to the differential reaction of one nematode species in different host species (i.e., host-induced changes) or because of distinct nematode species in these hosts (i.e., species complex). This paper focuses on specimens resembling O. leptospicularis f. leptospicularis and its closely related species (Ostertagia ostertagi f. ostertagi) collected from various hosts. Morphometric and molecular techniques were applied to assess host-induced changes in nematode morphology and to clarify its systematic classification. There was an overall effect of host species on measurements of nematodes resembling O. leptospicularis (both males and females), but the distinctiveness of the specimens from cattle Bos taurus were highlighted. The results obtained may suggest that the specimens of O. leptospicularis from cattle in Germany and cervids in central Europe belong to different strains. Furthermore, nematodes from the cervid strain appear to circulate within particular host species, which can be seen in the stated morphological variations.

Keywords: Bovidae; Cervidae; ITS-2; Ostertagia leptospicularis; morphology; morphometrics; strains.

Figure 1

Esophageal-intestinal (EI) valve of (a) Ostertagia leptospicularis from roe deer (Capreolus capreolus), (b) Ostertagia ostertagi from cattle (Bos taurus; arrows at anterior and posterior end; magnification 600×).

Figure 2

Spicules of Ostertagia leptospicularis from (a) roe deer (Capreolus capreolus), (b) cattle (Bos taurus) ventral view (magnification 400×).

Figure 3

Longitudinal cuticular ridges of Ostertagia leptospicularis males shown in transverse sections (a) at the esophageal-intestinal (EI) valves, n = 36, host roe deer (Capreolus capreolus); (b1–4) at the midbody: (b1) n = 31, cattle (Bos taurus); (b2) n = 32, cattle; (b3) n = 35, red deer (Cervus elaphus); (b4) n = 36, roe deer; (c1–4) above the anterior end of the spicules: (c1) n = 30, red deer; (c2) n = 31, cattle; (c3) n = 32, roe deer; (c4) n = 34, roe deer (magnification 600×).

Figure 4

Scatter plot of discriminant function analysis comparing selected morphological characteristics of Ostertagia leptospicularis males derived from different host species (brown crosses indicates particular centroides).

Figure 5

Scatter plot of discriminant function analysis comparing selected morphological characteristics of Ostertagia leptospicularis females derived from different host species (brown crosses indicates particular centroides).

Figure 6

Consensus tree depicting the ITS-2 similarity of newly obtained sequences of Ostertagia leptospicularis (1–MT954614 221bp, 2–MT954616 219bp, 3–MT954631 219bp, 4–MT956640 225bp, 5–MT954907 222bp, 6–MT956639 145 bp, 7–MT954410 150bp, 8–MT954415 149bp, 9–MT954592 152bp, 10–MT956639 145bp) and those available in the NCBI database. Bayesian posterior probabilities (PP) are given at each node.