Neotobrilus ampiei ( Joubert & Heyns, 1979 ) Tsalolikhin, 1981

Girgan, Chantelle, Marais, Mariette, Fourie, Hendrika, Tiedt, Lourens & Swart, Antoinette, 2019, Description of two new species, Aphanolaimus strilliae n. sp. (Nematoda: Aphanolaimidae) and Makatinus africanus n. sp. (Nematoda: Aporcelaimidae), and SEM observations on three known species from freshwater sources in the Telperion Nature Reserve (Mpumalanga, South Africa), Zootaxa 4651 (2), pp. 201-234 : 221-223

Neotobrilus ampiei ( Joubert & Heyns, 1979) Tsalolikhin, 1981

Figures 14–21

Measurements: Table 5

Description: Female (n = 13): Habitus curved ventrally to various degrees, body 1868–2439 μm long. Cuticle 1–4 μm thick at mid-body, annulated. Somatic setae numerous, spread unevenly over entire body. First somatic se- tum located 24–41 μm from anterior end. Lip region 24–36 μm wide, cephalic setae 13–16 μm long. En face view of head indicates one circlet consisting of six labial papillae, six long cephalic setae and four short cephalic setae. Cephalic setae originate from the cuticle, while cephalic papillae originate subcuticular. All setae and papillae appear to be hollow tubes. Amphids stirrup shaped with slit-like apertures, located 17–19 μm from anterior end. Stoma 35–44 μm long, half the width of lip region, consisting of two parts: A distinct barrel-shaped buccal cavity separated by two separate pockets. Each pocket contains a tooth and are separated by a narrowing of the cavity. First tooth is 18–24 μm from anterior end with second tooth 13–16 μm posterior to first. Oesophagus cylindrical and muscular, 345–437 μm long. Nerve ring not observed. Cardia 22–36 μm long with three prominent cells situated at junction of cardia and oesophagus. Excretory pore not observed. Reproductive system didelpic-amphidelphic, anterior tract (195–392 μm long) almost always slightly shorter than posterior tract (228–430 μm). Vulva a transversal slit situ- ated at 37–46 % of body. Vaginal musculature strong, vagina less than half corresponding body width. Advulval setae twice as long as somatic setae (mean length of 16.4 μm), located dorsally at one body width anterior and posterior to vulva. Uterine eggs observed in most female specimens, measuring 51–68 μm X 35 –56 μm with shell. Eggshell uniquely sculptured with several prominent tubercules. Pars dilatata oviductus rounded, containing flaggelloid sperm cells. Ovaries reflexed, oocytes arranged in single row except at growth point. Tail 255–354 μm long ending in rounded tip with a 3–5 μm spinneret and a subterminal setum. Rectum 31–47 μm long.

Male (n = 5): Habitus curved ventrally, body 1990–2320 μm long. Morphology of stoma and oesophagus similar to that of female. Spicule 69–80 μm long, medial outgrowth from ventral limb towards dorsal limb. Gu- bernaculum 19–26 μm long. Reproductive system diorchic, sperm cells flaggelloid. Ductus ejaculatoris muscular, its length corresponds with length of supplementary row, never exceeding it. Tail 181–211 μm long. Two rows of subventral somatic setae along row of supplements, setae directed anteriorly and consisting of two parts. Supplementary row consisting of six pre-cloacal supplements, three larger and three closest to the cloaca, smaller. The supplements lose complexity nearing the cloaca. Supplement 1 to supplement 3 (starting anteriad) are complex in structure with several tubercules, whereas Supplement 4-Supplement 6 less covered in tubercules and Supplement 6 the most simplistic. Distance between Supplement 2 and Supplement 3 is the shortest. Micro papillae present between supplements Supplement 3 and Supplement 4 (10–11 micropapillae), Supplement 4 and Supplement 5 (4–5 micropapillae) and Supplement 5 and Supplement 6 (5–6 micropapillae). According to SEM micropapillae appear as thin transversal slits.

Discussion: The Neotobrilus specimens collected in Telperion Nature Reserve was identified following a key from Tsalolikhin & Shoshin (2009). Neotobrilus ampiei is distinguished from all other species in this genus by the uniquely sculptured eggshells in the females and by the closely positioned supplements 2 and 3 in males. The current female specimens exactly matches those of the original description by Joubert & Heyns (1979). However, the males differ slightly in: spicule length (61–72 μm vs 69–80 μm) and c-value (9.26–13.26 vs 8.4–9.9). Neotobrilus ampiei is considered endemic as the only reports are from the type locality in the Eastern Cape Province and a second population in the North West Province described by Joubert & Heyns (1979). This is only the second report of this species.

Locality and specimens examined: Specimens of N. ampiei were found at the Waterhole (MP00031) site ( Table 1 ) and are deposited in the National Collection of Nematodes (ARC—Plant Health and Protection, Biosystematics, Pretoria) on slide numbers 50591–50599.

Figures

FIGURE 14. Female drawings Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 A) Anterior region showing oesophagus; B) Tail; C) Vulval region showing musculature of vagina; D) Anterior region showing structure of stoma and teeth pockets; E) Vulval region showing part of anterior genital tract with two eggs and full posterior tract with one egg.

FIGURE 15. Male drawings Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 A) Close up of supplements 3–6 showing position of micropapillae; B) Supplementary row S1–S6 (S1 starting anteriorly); Ductus ejaculatoris; spicule and gu- bernaculum; C) Anterior region showing stoma and arrangement of teeth pockets.

FIGURE 16. Scanning electron micrograph of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981; A) Lateral view of anterior end showing amphid (a); long cephalic setae (lcs), short cephalic setae (scc) and labial papillae (lp); B) Anterior end showing long cephalic setae (lcs), short cephalic setae (scc) and labial papillae (lp) and liplets (l); C) Close up of long cephalic setae (lcs) and labial papillae (lp), arrows indicating the opening of the sensory organs; D) Arrow indicating lateral cord; E) Ventral side of body showing vulva.

FIGURE 17. Scanning electron micrograph of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 A) Female tale showing spinneret and last somatic (caudal setae); B–C) Close up of tip of spicule (s) showing medial outgrowth; D) Male posterior part showing supplements S1–S6 and a row of ventrosublateral setae.

FIGURE 18. Scanning electron micrograph of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 ventral side of male showing distribution and direction of ventrosublateral setae (vsls); supplements S4–S6, and micropappilae (small ar- rows).

FIGURE 19. Scanning electron micrograph of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 A + C) Close up of supplements S2 and S3 (S1 identical to S2 and S3); B) Close up of ventrosublateral setae, arrow showing junction where two parts meet; D–F) Close up of supplement S4–S6.

FIGURE 20. Light microscopic pictures of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 female A) Vaginal region with three uterine eggs; B) Anterior end to end of posterior genital tract arrow indicating vulva; C) Labial region showing buccal cavity and two tooth pockets (T1 and T2).

FIGURE 21. Light microscopic pictures of Neotobrilus ampiei (Joubert & Heyns, 1979) Tsalolikhin, 1981 Male A); Posterior region showing supplements S1–S4 and Ductus ejaculatoris (DE); B) Arrow indicating flaggelloid sperm cells in male.