Figure 1
Oscheius indicus n. sp. (A) Entire male; (B) Entire female; (C) Pharyngeal region; (D) Anterior region; (E) Female reproductive system; (F) Male posterior region showing spicules and gubernaculum; (G) Male tail in dorso-ventral view (genital papillae and bursa); (H) Female posterior region.
Figure 2
Oscheius indicus n. sp. (A, B) Anterior region showing stoma; (C) Posterior pharynx.; (D) Genital papillae; (E) Anterior pharynx; (F) Vulva; (G) Male posterior region; (H) Female posterior region; (I) Lateral lines. (Scale bar: 20 μm).
Figure 3
Oscheius indicus n. sp. (A) Enface view showing six labial papillae (a to f), (B) Crochet needle-shaped spicules (C) Male posterior region showing genital papillae (GP1 to GP9), (D) Female posterior region showing anal opening (Scale bar: A = 2 μm; B & C = 10 μm, D = 5 μm).
Table 1
Morphometric data of Oscheius indicus sp. n. Measurements are in µm and in the form: mean ± standard deviation (range).
| Characters | Holotype female | Paratype females | Paratype males |
|---|---|---|---|
| n | 1 | 14 | 14 |
| L | 1,320 | 1,272.3 ± 111.7 (1,072–1,480) | 1,062.7 ± 104.5 (886–1,209) |
| a | 20.3 | 18.9 ± 1.1 (16.8–20.6) | 19.6 ± 1.6 (17.4–22.4) |
| b | 6.5 | 6.5 ± 0.4 (5.7–7.1) | 6.2 ± 0.6 (4.9–6.9) |
| c | 9.9 | 8.9 ± 0.9 (7.5–10.4) | 31.2 ± 2.8 (26.1–36.2) |
| c’ | 5.3 | 5.8 ± 0.4 (5.0–6.6) | 1.3 ± 0.1 (1.2–1.4) |
| V | 50.2 | 48.2 ± 1.8 (45.4–50.5) | – |
| Maximum body diam. | 65 | 67.8 ± 20.2 (59–82) | 54.4 ± 16.3 (46–64) |
| Lip width | 12 | 12.6 ± 1.1 (11–15) | 11.6 ± 0.7 (11–13) |
| Length of stoma | 16 | 15.4 ± 1.7 (13–18) | 15.6 ± 0.9 (14–17) |
| Corpus | 123 | 117.7 ± 6.1 (108–127) | 105.4 ± 4.0 (101–114) |
| Isthmus | 42 | 40.7 ± 3.4 (37–47) | 35.4 ± 3.5 (31–41) |
| Basal bulb length | 37 | 36.4 ± 2.2 (33–41) | 29.9 ± 1.4 (27–32) |
| Basal bulb width | 29 | 27.6 ± 1.8 (24–30) | 23.8 ± 0.9 (22–25) |
| Pharynx | 202 | 194.8 ± 9.8 (181–210) | 172.4 ± 6.0 (159–181) |
| Excretory pore from anterior end | 201 | 179.9 ± 15.1 (154–201) | 173.6 ± 9.7 (158–187) |
| Nerve ring from anterior end | 162 | 142.0 ± 14.1 (118–162) | 136.7 ± 7.6 (122–146) |
| Anterior gonad | 524 | 558.2 ± 43.2 (501–640) | – |
| Posterior gonad | 352 | 504.4 ± 90.3 (324–614) | – |
| Vulva body diam. | 64 | 66.4 ± 5.5 (58–80) | – |
| Vulva-anus distance | 525 | 512.1 ± 40.2 (447–576) | – |
| Rectum | 72 | 67.9 ± 5.8 (58–76) | 54.3 ± 4.3 (46–61) |
| Tail length | 133 | 142.6 ± 8.9 (131–156) | 34.2 ± 2.3 (32–39) |
| Anal body diameter | 25 | 24.8 ± 1.4 (23–28) | 25.6 ± 1.2 (24–28) |
| Pharynx gonad distance | 175 | 118.0 ± 31.6 (89–175) | 82.8 ± 17.2 (61–116) |
| Testis | _ | – | 883.0 ± 82.1 (760–1,035) |
| Spicule length along axis | _ | – | 60.0 ± 4.2 (54–66) |
| Gubernaculum | _ | – | 25.1 ± 1.2 (24–28) |
Figure 4
Molecular phylogenetic relationship of Oscheius indicus n. sp. (highlighted in bold) inferred using 28S D2/D3 extension region of 28 rDNA gene. The evolutionary history was inferred by the Bayesian analysis using the General Time Reversible substitution model with gamma-distributed rate variation across sites and a proportion of invariable sites (GTR+G+I). The posterior probability values exceeding 50% are indicated at appropriate clades. The scale bar indicates expected changes per site. Orange and green shaded boxes indicate insectivora and dolichura group, respectively.
Figure 5
Molecular phylogenetic relationship of Oscheius indicus n. sp. (highlighted in bold) inferred using ITS region. The evolutionary history was inferred by the Bayesian analysis using the General Time Reversible substitution model with gamma-distributed rate variation across sites and a proportion of invariable sites (GTR+G+I). The posterior probability values exceeding 50% are indicated at appropriate clades. The scale bar indicates expected changes per site. Orange and green shaded boxes indicate insectivora and dolichura group, respectively.