Geomonhystera mexiquense, 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 : 79-81

Geomonhystera mexiquense sp. n.

( Fig. 1 A–G ; Fig. 2 A–D )

Measurements. Tables 2 and 3.

Female (n=17). Body almost straight to slightly arcuate ventrad after fixation; cuticle 1 µm thick, with very fine striations; 0–15 (7±4.4) somatic setae concentrated in the cervical region; lips not fused; head convex continuous with body contour, width 13–16 (15.2 ±0.7) µm and height 3–5 µm; inner labial papillae very small, coniform, 2.0 µm long; outer labial setae unsegmented, 7–10 (9.0±0.8) µm long or 44–67% of head width; cephalic setae thin, 5–8 (6.1±0.9) µm long and 31–50% of head width; amphid apertures circular, 3.0–5.0 (4.0±0.4) µm diameter and 15–22 (19.1±1.9) µm from the anterior margin to the head; both amphids at the same level; no denticles observed in the lumen of the stoma; pharynx muscular, 147–174 µm (160±8.4) long or 16–24 (18.4±2.1) % of the body length, 325– 697 (543±86.2) µm from the vulva and 353–726 (572±85.4) µm from the anus; nerve ring at 69–98 (76±7.4) µm from the anterior end; cardia 6–12 (9.5±1.7) µm long and 8–15 (9.5±1.6) µm wide, composed of three conspicuous cells; outer zone of intestinal walls with many granular refractive inclusions; rectum thick and muscular, 27–36 (31±2.5) µm long and 0.9–1.75 (1.5±0.2) times the anal body diameter; anterior anus lip slightly protruding; distance between vulva and anus 31–42 µm (36±3.1) or 1.5–2.0 (1.7±0.2) times anal body diameter; gonad (n=10) 198–358 (249±48) µm long, ovary short with one row of oocytes, 24–33 (28±2.9) % of body length. Vagina short, with slightly thickened walls 4–10 (6.6±1.7) µm long, vulval lips slightly protruding, post-vulval uterine sac absent; tail tapering evenly,112– 135 µm (123±6.6) µm long and 19–23 (21±1.1) µm wide or 11–19.5 (14.3±1.9) % of the body length, with a few caudal setae; three caudal glands, posterior to the anus and in line, with ducts opening into an ampulla 5–11 (7.4 ±1.6) µm long and then ducted through the conspicuous, terminal, spinneret, 2–3 µm long.

Male. Unknown.

Diagnosis and relationships. Geomonhystera mexiquense sp. n. has fine cuticlar striation and few body setae; the outer labial setae, 44–67% of the head width, are not segmented, the cephalic setae are thin, not segmented and 31–50% of the head width; vulval lips protrude slightly; the vulva-anus distance is 31–42 (36±3.1) µm and the rectum length 27–36 (31±2.5) µm; caudal glands are ducted into a common ampulla, 5–11 (7.4±1.6) µm long; the spinneret is conspicuous, 2–3 µm long.

Geomonhystera mexiquense sp. n. is close to G. breviseta Brzeski, 1993 in the length of the body, the thin cuticle, the position of the vulva, the length of the rectum and in having setae scattered along body. It differs in having longer cephalic setae, 5.0–8.0 (6.1) vs. 3.0–5.0 (4) µm, the greater range of the outer labial setae in relation to head width, 43.8–67 (59) vs. 25–45 (34) %, and in having a smaller amphid diameter, 3.0–4.0 (3.9) vs. 4.0–5.0 (4.3) µm. It is also close to G. karuni Siddiqi & Shahina, 2004 in the vulva-anus distance, in the length of the outer labial setae, in the length of the pharynx and in the scattered body and tail setae. It differs in the finely-striated vs. smooth cuticle, in the index a, 22–39 (32±4.6) vs. 39–48 (42), in the index c’, 5.3–6.4 (6.0) vs.6.5–9.0, and in having a wider body, 24–30 (26.9) vs. 20–26 µm.

Geomonhystera mexiquense sp. n. is similar to G. galindoi sp. n. in the body length, the fine transverse striae and sparsely-distributed body setae, the position of the vulva and the indexes a and b. The species differ in that there are males present in G. galindoi sp. n. but not in G. mexiquense sp. n. Two D2–D3 of 28S rRNA gene sequences obtained from two samples of G. mexiquense sp. n. were different by 0.9% (7 bp) from each other and in 17 % (119–120 bp) from those of G. galindoi sp. n. and by 8.4–8.5% (60–61 bp) from that of G. longispiculata sp. n.

The G. mexiquense sp. n. population from the type locality in Juchitepec is similar to a Geomonhystera population from San Diego Huehuecalco, Municipio de Amecameca in the following characters: body length, head width, length of the outer labial and cephalic setae, length of the pharynx and index b, length of the rectum, position of the vulva and vulva-anus distance. We consider the population from San Diego Huehuecalco, Municipio de Amecameca to be G. mexiquense sp. n.

Type locality and habitat. Juchitepec, México State, 19° 03' 45.2" N, 98° 49' 39.1" W, 2544 m asl, collected on January 23, 2009 and January 24, 2012 from moss on a rock and on the trunk of Quercus crassipes Humb. & Bonpl. , respectively. A second locality and habitat is from moss growing on a Tepozan tree ( Buddleia cordata Kunth. ) near San Diego Huehuecalco, Municipio de Amecameca 19° 05' 46.3" N 98° 44' 44.6" W, elevation 2529 m asl.

Type specimens. Holotype female on slide 10384; five paratype females on slide 10385 in the Colección Nacional de Helmintos Instituto de Biología, Laboratorio de Helmintologίa, Universidad Nacional Autónoma de México ( CNHE). Other type material is deposited in the University of California, Riverside, Nematode Collection ( UCRNC) on slide 28539, Wageningen University Nematode Collection (WaNeCo) on slide WT3716, and the Colegio de Postgraduados Nematode Collection ( CPNC) on slide number A-097.

Etymology. The species name recognizes that the type locality, Juchitepec, is in the State of México.

Figures

FIGURE 1. Geomonhystera mexiquense sp. n.; Female (A–G). A, B: Anterior end body; C: Pharyngeo-intestinal junction; D: Vulva-anus region; E: Posterior end body; F: Spinneret; G: Entire body.

FIGURE 2. Geomonhystera mexiquense sp. n. scanning electron micrographs; Female (A–D). A: Entire body, lateral view; B: Anterior end, lateral view; C: Face view; D: Somatic setae.