Inbionema, Loof and Zullini, 2000

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 : 1265

Inbionema

Loof and Zullini (2000) described the new genus Inbionema from Costa Rica, with I. biforme as its type and only species. It was distinguished from Oriverutus in body size (more than 1.5 versus under 1.3 mm in Oriverutus ), the morphology of lip region (lips deeply separate versus partly separate; two circles versus one circle of papillae in lateral view), odontostyle length (> 38 versus up to 18 µm), arrangement of S 1 N (close together versus far apart), cardiac cells (absent versus present), tail length (c' = 1.1–1.6 versus 1.9– 5.6), and shape of spicules (very thick versus normal). One female and one male paratype, deposited in the nematode collection of the University of Jaén ( Spain), were available to study ( Figure 8 ). Light microscope and SEM pictures (see Figure 8A, D and Loof and Zullini’ s Fig. 6 , respectively) show that the lip region of Inbionema is totally comparable with that found in Oriverutus species ( Figure 2 in this contribution), with no significant difference. Regarding the location of pharyngeal gland nuclei, it displays a pattern ( Figure 8B ) similar to that observed in some Oriverutus species, for instance O. ecae and O. tropicus (see above). It is now known (see above) that cardiac cells may be either present or absent in Oriverutus species. Hence, the main differences between these genera are reduced to morphometrics, since I. biforme is significantly larger than Oriverutus species, although, taking into consideration the current described diversity for the former genus, such differences are now smaller: body length (1.5–2.2 versus up to 1.26 mm in O. occidentalis ), odontostyle length (39–66 versus up to 26 µm in O. longistylus ) –it is remarkable that Loof and Zullini emphasized that within the same population they found two groups of specimens significantly differing in odontostyle length, 39–43 and 59–66 µm, without intermediate values–, tail length (c' = 1.1–1.6 versus c'= 0.8–1.8 in O. ecae ), and spicule length (69–85 versus up to 40 µm in O. pagarus ). Andrássy (2009) stated (p. 373) that “ Inbionema strongly resembles Oriverutus …, these genera may be identical”. Taking into account that Oriverutus seems to be a highly diverse taxon in Costa Rica, the species described as I. biforme might represent one of its evolutionary lines in which the general size suffered an important increase. Then, Inbionema is herein considered to be identical to Oriverutus , and its only species transferred to the former genus as Oriverutus biformis ( Loof and Zullini 2000) comb. nov.

Figures

Figure 2. Lip region of Oriverutus species (scanning electron microscopy). (A, D) Oriverutus asaccatus (Dhanachand and Jairajpuri 1980) Ahmad and Jairajpuri, 1987; (B, E) Oriverutus sundarus (Williams, 1964) Siddiqi, 1971; (C, F) Oriverutus tropicus Ahmad and Shaheen, 2003; (G-I) Oriverutus occidentalis Peña-Santiago and Peralta, 1991. A–C: Sublateral or ventral view; D–E: frontal view. Scale bars 5 µm.

Figure 6. Caudal region of Oriverutus species (light microscopy). (A) Oriverutus asaccatus (Dhanachand and Jairajpuri 1980) Ahmad and Jairajpuri, 1987; (B) Oriverutus belloi Liébanas et al., 2011; (C) Oriverutus costaricensis Liébanas and Peña-Santiago, 2011; (D) Oriverutus ecae (Ahmad and Shaheen 2005) Andrássy, 2009; (E) Oriverutus hemihystera Liébanas and Peña-Santiago, 2011; (F) Oriverutus microdorus Ahmad and Siddiqi, 1997; (G) Oriverutus vanisti Peña-Santiago et al., 2013; (H) Oriverutus sundarus (Williams 1964) Siddiqi, 1971. Scale bars: 10 µm, except G = 20 µm.

Figure 8. Inbionema biforme Loof and Zullini, 2000 (light microscopy). (A) Anterior region in median, lateral view; (B) Pharyngeal expansion, with arrow heads pointing at pharyngeal gland nuclei; (C) Uterine eggs; (D) Spicules; (E) Lip region Spicules; in surface, lateral view; (F) Male, caudal region; (G) Female, caudal region; (H) Pharyngo-intestinal junction; (I) Ventromedian supplements. Scale bars: A, G = 10 µm; B, C = 50 µm; D, F, H, I = 20 µm; E = 5 µm.