Pseudacrobeles (Bunobus) rotundilabiatus, Abolafia, Joaquín & Peña-Santiago, Reyes, 2013

Abolafia, Joaquín & Peña-Santiago, Reyes, 2013, Iberian species of the subgenus Bunobus De Ley, Siddiqi & Boström, 1993 (Nematoda, Rhabditida, Cephalobidae), with description of Pseudacrobeles (Bunobus) rotundilabiatus sp. n. and comments on the subgenus, Zootaxa 3640 (2), pp. 200-212 : 204-208

Pseudacrobeles (Bunobus) rotundilabiatus sp. n.

( Figs 1–3 )

Material examined. Sixteen females and two males from four localities, in variable states of preservation.

Morphometrics. See Table 1 & 2.

Description

Population from Las Acebeas, province of Jaén (12, 2):

Adult: Moderately slender to slender nematodes of small size, 0.68–0.81 mm long. Body cylindrical, tapering towards both extremities but more so towards the posterior end since the caudal region is conical. Habitus after fixation nearly straight to curved ventrad, C-shaped, more ventrally curved, especially in the posterior body region, in males. Cuticle annulated, with annuli 1.0–1.5 Μm wide at mid-body. Lateral field marked by three longitudinal incisures, occupying about one-sixth of body diameter at mid-body and extending to phasmid level. Lip region almost continuous with the adjacent body and displaying bilateral symmetry: subdorsal and subventral lips rounded and low, lateral lips reduced, cephalic and labial probolae absent, and with 6+4 papillae. Amphid aperture small, slit-like, located at base of lateral lips. Stoma cephaloboid, 2.1–2.5 times the lip region width long: cheilorhabdions bar-shaped in optical section, and gymnostom clearly narrower than cheilostom and as wide as stegostom. Pharyngeal corpus cylindrical, 3.0–3.7 times as long as isthmus; isthmus distinctly demarcated from corpus; and basal bulb ovoid, 1.5 times longer than wide, with well developed valves. Cardia conoid, surrounded by intestinal tissue. Nerve ring embracing the posterior part of corpus, close to isthmus, at 65–74% of the total neck length. Excretory pore at 65–71% of total neck length or 92–97 annuli from the anterior end (R ep), close the hemizonid at isthmus level. Deirid located in lateral field at isthmus level, at 76–78% of the neck length or 103–108 annuli from the anterior end (R dei). Intestine with a cardiac part (that is, an anterior section bearing significantly wider lumen) three times as long as the corresponding body diameter.

Female: Reproductive system cephaloboid, monodelphic-prodelphic. Ovary directed posteriorly, with or without post-vulval double flexure; germinal part expanded, with oocytes arranged in a single row; distal part without oocytes. Oviduct one-third of the corresponding body diameter long. Spermatheca well developed, nearly twice the body diameter long. Uterus narrow, tubular, almost three times the corresponding body diameter long; its distal part having slender walls that become thicker at the proximal part. Postvulval sac 1.6–2.0 times as long as the corresponding body diameter, with a transverse septum, dividing in two regions, the proximal one narrower, and the distal one more swollen. Vagina extending inwards to one-half of body diameter. Rectum 1.7–2.3 anal body widths long, with three rectal muscle cells, two subventral and one dorsal. Tail conical elongated, with 42–67 annuli on its ventral side, ending in a lanceolate mucro slightly tuberculate proximally. Phasmids at 32–33% of tail length.

Male: Genital system monorchic, dextral. Testis reflexed ventrally anteriorly. Spicules curved ventrad: manubrium rounded, calamus narrow, and lamina with a thickened central part and a longitudinal incisure. Gubernaculum curved ventrad. Tail conical, slightly curved ventrad, having a terminal, conical mucro. Genital papillae eight pairs, three pairs precloacal and five pairs postcloacal or caudal: two anterior to phasmid (one lateral and another subventral), one posterior to phasmid (subventral), and three very prominent close tail tip (one subdorsal and two subventral); one single midventral papilla located on the precloacal lip.

Diagnosis. The new species is characterized by a body length of 624–805 Μm in females and 670–714 Μm in males, lateral field with three incisures, fading out near the phasmid, lip region continuous with the adjacent body, subdorsal and subventral lips rounded, lateral lips very reduced, stoma 13–17 Μm long, pharyngeal corpus 3.0–4.3 times as long as isthmus, V = 63–74, spermatheca 22–62 Μm long, postvulval sac 1.6–2.0 times the body diameter long, female tail conical elongated (59–83 µm, c = 9.7–11.6, c' = 4.5–6.8) ending in a lanceolate mucro slightly tuberculate proximally, male tail conical (38–40 µm, c = 10.1–16.8, c' = 3.9), spicules 25 µm long, and gubernaculum 14 µm long.

Relationships. The new species resembles P. (B.) arboricola , P. (B.) bostromi , P. (B.) cruzi , P. (B.) loofi , P. (B.) pseudolatus and P. (B.) pulcher . It differs from P. (B.) arboricola in having a larger female body (L = 0.64–0.81, n = 16 vs 0.53–0.68 mm, n = 27), comparatively longer pharyngeal corpus (3.0–4.3 vs 1.5–2.3 times the isthmus), more posterior excretory pore (at pharyngeal corpus-isthmus junction vs at anterior part of pharyngeal corpus), and longer spicules (25 vs 15-19 μm). From P. (B.) bostromi in the position of excretory pore (vs at posterior part of corpus), and deirids (at isthmus level vs at level of the posterior part of pharyngeal corpus). From P. (B.) c r u z i in its larger female body (vs L = 0.48–0.60 mm, n = 9) and shorter female tail (59–83 vs 90–116 Μm). From P. (B.) l o o f i by having larger female body (vs L = 0.30–0.43 mm, n = 19), comparatively larger pharyngeal corpus (3.0–3.7 vs 1.9–2.8 times the isthmus) and longer post-uterine sac (25–40 vs 2–11 µm). From P. (B.) pseudolatus in its larger female body (vs L = 0.41–0.47 mm, n = 3), comparatively longer pharyngeal corpus (3.0–3.7 vs 2.7 times the isthmus) and longer spicules (25 vs 15–20 µm). And from P. (B.) p ul c he r by having a larger female body (vs L = 0.53–0.68 mm, n = 19), shorter female tail (59–83 vs 92–111 Μm), and male tail with acute mucro (vs without mucro). From all species, it also differs in the morphology of the female tip tail (with a slightly tuberculate, lanceolate mucro vs acute tip, except in P. (B.) bostromi , which has a ragged-mucronate terminus).

Type locality and habitat. Province of Jaén, Sierras de Cazorla, Segura and Las Villas Natural Park, Sierra de Segura, near road to Las Acebeas (coordinates 38º21'52'' N – 2º34'13'' W), where it was collected from soil in a forest whose dominant plant trees were Pinus nigra Arn. subsp. salzmannii (Dunal) Franco, Corylus avellana L., Quercus faginea Lam. , and Platanus x hispanica Mill. ex Muenchh.

Other localities and habitats. (i) Province of Málaga, Axarquía shire, near the road from El Trapiche to Triana, in association with Persea americana Miller. ; (ii) Province of Málaga, Sierra Bermeja, Casares, in association with Eucalyptus sp.; and (iii) province of Málaga, Sierra de Grazalema Natural Park, Venta el Hondón, in association with Populus alba L.

Type material. Holotype, six female and two male paratypes deposited in the nematode collection of Departamento de Biología Animal, Universidad de Jaén, Spain; and one female paratype deposited in the nematode collection of the Swedish Museum of Natural History, Stockholm ( Sweden).

Figures

FIGURE 1. Pseudacrobeles (Bunobus) pseudolatus (Hernández, 1990) De Ley, Siddiqi & Boström, 1993 (paratype). A: Neck. B: Anterior end. C, D: Lip region (at lateral view and at frontal view, respectively). E: Entire female. F: Vulva. G: Female genital system. H: Entire male. I, J: Female posterior end. K: Male posterior end.

FIGURE 2. Pseudacrobeles (Bunobus) pseudolatus (Hernández, 1990) De Ley, Siddiqi & Boström, 1993 (paratype, LM). A: Neck. B, C: Anterior end (at superficial view and at stoma level, respectively). D: Vagina. E: Female posterior end (arrow points the phasmid). F: Male posterior end (arrows point some genital papillae).

FIGURE 3. Pseudacrobeles (Bunobus) rotundilabiatus sp. n. A: Neck. B, C: Anterior end. D: Entire female. E: Entire male. F, G: Reproductive female system. H, I: Female posterior end. J: Male posterior end.