Geomonhystera chiautzingoensis, Prado-Vera & Ferris & Subbotin, 2018

Prado-Vera, Ignacio Cid Del, Ferris, Howard & Subbotin, Sergei A., 2018, Six new and one known species of Geomonhystera (Nematoda, Monhysteridae) from moss, an epiphytic plant and soil in México and Ecuador, Zootaxa 4471 (1), pp. 76-110 : 93-97

Geomonhystera chiautzingoensis sp. n.

( Fig. 11 A–I ; Fig. 12 A–D ; Fig. 13 A–D )

Measurements. Tables 2, 3 and 4.

Female (n=9): Body of fixed specimens curved ventrally with the posterior end hook-shaped; cuticle 1 µm thick, with exceedingly fine striations; body with a few thin setae, 3 µm long, in cervical, mid-body and vulva-anus areas; we observed 0–8 setae on the tails of specimens; head 9–12 (10±0.9) µm wide; lips triangular, fused at the base and clearly separated distally; inner labial papillae very small, coniform, 1 µm long; outer labial setae unsegmented, 4–7 (5.0±0.9) µm long or 36–58 (45±6.9) % of head width; cephalic setae very thin, 3–5 (3.6±0.7) µm long and 27–42 (33±5.9) % of the head width; amphid apertures rounded, 4–5 (4.3±0.5) µm diameter and 16– 25 (20.7±2.9) µm from the anterior end or 1.6–2.3 (2.0±0.2) times the head width; pharynx muscular, 133–185 (159±16.4) µm long; nerve ring at 66–87 (79±7.1) µm from the anterior end; cardia 6–11 (8.7±1.9) µm long and 6– 14 (9.3±2.2) µm wide; rectum muscular 25–44 (31±5.9) µm long and 0.6–2.2 (1.4±0.7) times anal body diameter; anterior anal lip slightly protruding; vulva-anus distance 37–50 (42±4.4) µm or 2.0–3.4 (2.5±0.4) times anal body diameter.. Gonad (n=3) 292–509 (380±114.2) µm long, ovary short with one row of oocytes, 37–49 (41±6.5) % of body length; vulval lips slightly protruding; vagina with slightly thickened walls, 5–10 (7.0±1.7) µm long, postvulval uterine sac absent. Tail tapering evenly, curved ventrally, 79–131 (104±19.4) µm long or 10–13 (12.1±1.3) % of the body length; three caudal glands, posterior to the anus and in line, ducted into a common ampulla, 8–10 (8.7±1.1) µm long, and opening through a conspicuous, terminal spinneret, 2 µm long.

Male (n=13): After fixation, body curved ventrally after fixation with the posterior end hook-shaped; cuticle 1

µm thick, with exceedingly fine striations; somatic setae rare to few; head 9–12 (10.4±0.9) µm wide; lips fused; inner labial papillae very small, coniform 1 µm long; outer labial setae unsegmented, 3–7 (4.5±1.3) µm long or 27– 64 (43±11.1) % of head width; cephalic setae thin, 2–5 (3.5±1.0) µm long or 18–50% of head width; amphid apertures rounded, 4–5 µm diameter and 17–26 (21±3.0) µm, or 1.7–2.4 times the head width from the anterior edge of the amphid to the head end; both amphids at the same level; pharynx muscular 132–188 (159.7±17.9) µm long; nerve ring at 52–92 (74±17.3) µm from the anterior end; cardia 4–10 (6.1±1.6) µm long and 6–9 µm wide, composed of conspicuous cells. Copulatory spicules equal in length, slightly arcuate, 27–50 (33.5±6.2) µm long, with acute tips and non-cephalate; gubernaculum 9–11 (10.2±0–8) µm long; tail 70–144 (111±18.5) µm long with a few thin setae (4–11 observed), ending in conspicuous, terminal, spinneret 2–3 µm long.

Diagnosis and relationships. Geomonhystera chiautzingoensis sp. n. has fine cuticular striation and a few tiny body setae; the outer labial setae are unsegmented, 4.0–7.0 (5.0±0.9) µm long; the amphids are 16–25 µm or 1.6–2.3 times the head width from the anterior end, the vulva-anus distance is 37–50 (42±4.4) µm and 2.0–3.4 times anal body diameter.. Body length of males 0.7–1.0 (0.85±0.1) µm, the spicules 27–50 µm long and the tail 70–144 µm long.

Geomonhystera chiautzingoensis sp. n. has extremely fine striations of the cuticle; the outer labial and cephalic setae are <50% of head width. It is close to G. steineri in the length of the body, the very few and short body setae, and the shape and size of the spicules. It differs from G. steineri in the somewhat smaller head width, 9.0–12.0 (10.4) vs. 11.0–15 µm.in the amphid diameter, 4.0–5.0 (4.3) vs. 1.0–1.5 µm the amphid to head/head width, 1.6–2.3 (2.0) vs. 1.2–1.3, and the tail length/vulva-anus distance, 1.9–2.9 (2.5) vs. 3–4. It differs from G. villosa in having a few thin somatic setae vs abundant setae, shorter outer labial and cephalic setae, 4.0–7.0 (4.75) and 3.0–5.0 (3.5) vs.12 and 6 µm, respectively, the length of the outer labial setae as a percentage of head width, 35.4–58.3 (45) vs. 66–75 %, and the amphid diameter, 4.0–5.0 (4.3) vs. 6.

Geomonhystera chiautzingoensis sp. n. is distinguished from G. antarcticola Andrássy, 1998 by having a few thin somatic setae, by the somewhat shorter body length 0.69–1.1 vs. 1.1–1.3 mm, index a, 31.3–37.4 (34) vs. 38– 46, the head width, 9.0–12.0 (10.4) vs. 15. The length of the outer labial setae, 4.0–7.0 (4.75) vs. 9.0–10.0 µm, and the pharynx length, 133–185 (159) vs. 220 µm. It differs from G. ecuatoriana sp. n. in the index b, 4.9–6.0 (5.4) vs. 6.3–6.6 (6.5), the amphid to head distance/head width. 1.6–2.3 (2.0) vs. 1.2–1.5 (1.3), and the pharynx length as % of body length, 16.7–20.4 (18.4) vs. 15.0–15.8 (15.5). It differs from G. longispiculata sp. n. in the length of the spicules, 27–50 (34) vs. 55–85 (75) µm.

Type locality and habitat. Moss on trunk of Crataegus mexicana Moc & Sesse trees, Chiautzingo, Puebla State, México, 19° 47´N, 98° 47´W, elevation 2386 m asl.

Type specimens. Holotype female on slide 10396; allotype male on slide 10397 and one paratype female on slide 10398 deposited in CNHE. Paratypes are deposited in UCRNC on slide number 28543, WaNeCo on slide number WT3720, and CPNC on slide number A-101.

Etymology. The name of the species refers to the town where the specimens were collected.

Figures

FIGURE 11. Geomonhystera chiautzingoensis sp. n. Female (A, D, G). A: Anterior end body; D: Pharyngeo-intestinal junction; G: Vulva-anus region. Male (B, C, E, F, H). B: Anterior end body; C. Sperm; E: Pharyngeo-intestinal junction; F: Cloacal region; H: Posterior end body; I: Body shape, females and males.

FIGURE 12. Geomonhystera chiautzingoensis sp. n. scanning electron micrographs; Female (A–D). A: Anterior end, lateral view; B: Amphid and head, lateral view; C: Close up anterior end, antero-latero-ventral view; D: Posterior end body, dorsolateral view.

FIGURE 13. Geomonhystera chiautzingoensis sp. n. scanning electron micrographs; Male (A–D). A: Anterior end body, lateral view; B: Face view, latero-dorsal view; C: Precloacal cuticular folds region, lateral view; D: Precloacal cuticular folds and cloaca, ventral view.