Ecanema, Ahmad and Shaheen, 2005

Peña-Santiago, Reyes, Liébanas, Gracia & Ahmad, Wasim, 2014, Taxonomy of the genus Oriverutus Siddiqi, 1971 (Nematoda: Dorylaimida: Nordiidae), Journal of Natural History 48 (21), pp. 1253-1278 : 1262

Ecanema

When originally proposed, this genus had E. ecae as its type and only species, Ahmad and Shaheen (2005) distinguished it from Oriverutus on the basis of three main differences: the tripartite (versus bipartite) nature of pharynx, S 1 N 1 of similar (versus dissimilar) size as DN, and absence (versus presence) of hiatus. Andrássy (2009) regarded Ecanema as a junior synonym of Oriverutus , stating that (p. 375) “neither the oesophageal structures nor the position of the supplements show any differences between these genera”. Liébanas et al. (2011) studied in detail one female of E. ecae (reported as Oriverutus ecae ) from Costa Rica and found that it fits the Oriverutus pattern very well, especially regarding the most characteristic feature of this genus, the lip region morphology ( Figures 1F and 7A ), hence accepting Andrássy’ s (2009) criterion. Nevertheless, O. ecae is a peculiar member of Oriverutus by having especially slender (but not non-muscular, as originally described) anterior portion of pharynx, a comparatively long pharyngeal enlargement with a characteristic narrowing ( Figure 7E ), and refractive elements at the distal portion of uterus, close to the sphincter ( Figure 5B ), but these characters should be interpreted as intrageneric rather than intergeneric variations. Regarding the size of S 1 N 1 compared with DN, a re-examination of the female of O. ecae studied by Liébanas et al. (2011) confirmed that S 1 N are larger than S 2 N and that S 1 N are more or less similar in size to DN ( Figure 7B–D ); nevertheless, an identical scheme occurs in other Oriverutus species, for instance in O. tropicus , as revealed by the re-examination of well-preserved specimens of this species. Obviously, the absence of hiatus in O. ecae is not a relevant difference because at least two other Oriverutus species bear ventromedian supplements within the range of spicules (see above). Hence, Andrassy’ s action, synonymysing Ecanema with Oriverutus , is solidly founded and well justified.

Figures

Figure 1. Lip region of Oriverutus species in median, lateral view (light microscopy). (A) Oriverutus andrassyi Peña-Santiago et al., 2013; (B) Oriverutus asaccatus (Dhanachand and Jairajpuri 1980) Ahmad and Jairajpuri, 1987; (C) Oriverutus belloi Liébanas et al., 2011; (D) Oriverutus costaricensis Liébanas and Peña-Santiago, 2011; (E) Oriverutus hemihystera Liébanas and Peña-Santiago, 2011; (F) Oriverutus kalikus Gambhir et al., 2008; (G) Oriverutus sundarus (Williams 1964) Siddiqi, 1971; (H) Oriverutus tropicus Ahmad and Shaheen, 2003. Scale bars: A–F, H = 10 µm; G = 5 µm.

Figure 5. Female genital system of Oriverutus species (light microscopy). (A) Oriverutus asaccatus (Dhanachand and Jairajpuri 1980) Ahmad and Jairajpuri, 1987; (B) Oriverutus ecae (Ahmad and Shaheen 2005) Andrássy, 2009 (arrow head pointing at refractive elements inside distal part of uterus); (C) Oriverutus tropicus Ahmad and Shaheen, 2003; (D) Oriverutus sturhani Ahmad and Shaheen, 2003; (E) Oriverutus istvani Peña-Santiago et al., 2013. Scale bars: A–C = 10 µm; D, E = 5 µm.

Figure 7. Morphological features of Oriverutus ecae (Ahmad and Shaheen 2005) Andrássy, 2009 (=Ecanema ecae) (light microscopy). (A) Anterior region in median, lateral view; (B–D) Pharyngeal expansion, with arrow heads pointing at pharyngeal gland nuclei: DN in (B), S1N1 and S2N1 in (C), and S1N2 and S2N2 in (D); (E) Pharyngeal enlargement, with arrow head pointing at DN. Scale bars: A = 5 µm; B–E = 20 µm.