Oxysomatium petrolinensis, Felix-Nascimento & Vieira & Muniz-Pereira & Moura & Ribeiro & Oliveira, 2020

Felix-Nascimento, Gabriela, Vieira, Fabiano Matos, Muniz-Pereira, Luís Cláudio, Moura, Geraldo Jorge Barbosa De, Ribeiro, Leonardo Barros & Oliveira, Jaqueline Bianque De, 2020, Two new species of Cosmocercidae (Nematoda: Cosmocercoidea) of Leptodactylus macrosternum Miranda-Ribeiro (Anura: Leptodactylidae) from Caatinga Biome Brazil, Zootaxa 4877 (2), pp. 274-290 : 276-277

Oxysomatium petrolinensis n. sp.

( Fig. 2 and 3 )

General. Sexual dimorphism not evident. Presence of narrow lateral body alae and numerous somatic papillae in both sexes ( Fig. 2C, D, E, F, I , 3A, C, F ). Cephalic end with three lips and triangular buccal aperture ( Fig. 2B , 3B ). Dorsal lip with two large papillae on the edge; a small posterior papilla, on the same longitudinal line as each large papilla, totalling four papillae. ( Fig. 2B , 3B ). Lateroventral lips with two papillae on the edge of each lip, with the ventral papilla larger than the medial which is close to the buccal aperture; lateral to the medial papilla has one small papilla, totalling three papillae in each lateroventral lip ( Fig. 2B , 3B ). Lateral amphids ( Fig. 2B , 3B ). Oesophagus oxyuriform, divided into four parts: pharynx, corpus, isthmus and bulb ( Fig. 2C, D ). Nerve ring anterior to excretory pore, located between the anterior third and middle third of the oesophagus ( Fig. 2C, D ). Excretory pore located at the level of oesophageal isthmus, between the middle third and the posterior third of the oesophagus ( Fig. 2C, D ).

Male (based on 10 specimens): Total body length 1.8–2.8 (2.6±0.3) mm, body width at level of oesophagus-intestinal junction 82–135 (111±14). Total oesophagus length 404–526 (482±34); pharynx 29–40 (34±3) long, corpus 280–375 (328±27) long, isthmus 20–44 (35±7) long, bulb 74–90 (84±4) long. Nerve ring 173–298 (215±33) and excretory pore 330–368 (346±23) from anterior end. Lateral body alae that appear at the level of the initial third of the oesophagus, anterior to nerve ring ( Fig. 2C ), and ends up before the cloaca, between the second and third pairs of precloacal papillae ( Fig. 2F , 3C ). Caudal papillae slightly larger in size than somatic papillae ( Fig. 3 A–F). Cloacal aperture has protuberances within the posterior border that form a row of cuticular fringes ( Fig. 3C, D ). Posterior region with a total of 16 pairs of papillae and one unpaired medial precloacal papilla (8+1:1:7) ( Fig. 2 E-G, 3C–E). Eight pairs of precloacal papillae, five lateroventral pairs, with the first located at level of proximal end of spicules and the fifth pair at level of the gubernaculum, the other three pairs lateroventral on the anterior border of cloaca ( Fig. 2E, G , 3C, D ). One unpaired medial precloacal papilla in the centre of a protuberance on the anterior border of cloacal aperture ( Fig. 2E, G , 3C, D ). One pair of lateral adcloacal papillae ( Fig. 2E, G , 3C, D ). Seven pairs of postcloacal papillae, of which the first two pairs are lateroventral, close together, with the second pair posterior and diagonal to the first pair; the third is laterodorsal and distant from the first two; the fourth pair is lateroventral close to the third pair; the fifth pair is dorsal, between the fourth and sixth pair. Sixth pair lateral and close to the tip of tail; the seventh pair is lateroventral and slightly later than the sixth pair ( Fig. 2 E–G, 3C, E). Phasmids not found. Spicules equal and slender, with rounded proximal end and sharply pointed distal end, not alate ( Fig. 2E, F ), 187– 283 (207±28) long. Gubernaculum present, oval in ventral view, with lateral and distal margins more sclerotized in relation to the proximal region ( Fig. 2G, H ), 56–80 (68±8) long. Tail conical with short filamented distal end ( Fig. 2 E-G, 3C, E), 161–218 (182±15) long .

Female (based on 10 specimens): Total body length 3.2–3.7 (3.4±0.6) mm, body width at level of oesophagusintestinal junction 137–180 (160±16). Total oesophagus length 435–580 (516±48); pharynx 30–45 (37±4) long, corpus 236–405 (336±52) long, isthmus 31–45 (38±4) long, bulb 90–128 (104±11) long. Nerve ring 204–350 (236±45) and excretory pore 345–420 (388±24) from anterior end. Lateral body alae originate at the level of the initial third of the oesophagus, anterior to nerve ring, and terminate posterior to anus. Didelphic and amphidelphic, with the ovary of the anterior uterus located posterior to the vulvar opening and the ovary of the posterior uterus located anterior to the vulva ( Fig. 2A ). Vulva post equatorial, slightly protruded, between 2nd and 3rd thirds of the body, 2–2,4 (2.1±0,1) mm from anterior end. Ovijector thin and muscular along its entire length, anteriorly directed ( Fig. 2J ). Oval larvated eggs in ovijector ( Fig. 2J ), 80–115 (98±9) long and 40–83 (57±9) width. Tail conical, with filamented distal end ( Fig. 2I , 3F ), 201–247 (224±13).

Figures

FIGURE 2. Oxysomatium petrolinensis n. sp. (A) total female length. (B) anterior end, male, apical view. (C) anterior region, male, ventral view. (D) anterior region, male, lateral view. (E) posterior region, male, ventral view. (F) posterior region, male, lateral view. (G) tail, male, lateral view. (H) gubernaculum, ventral view. (I) tail, female, lateral view. (J) vulva, ovijector and eggs, lateral view.

FIGURE 3. Oxysomatium petrolinensis n. sp. (A) anterior region, male, dorsal view. (B) anterior end, male, dorsal view (white arrows indicate the cephalic papillae). (C) posterior region, male, latero ventral view (white arrows indicate post cloacal papillae). (D) cloacal region, male, latero ventral view. (E) tail filament, male, latero ventral view. (F) tail, female, latero venral view. (*—somatic papillae; 1st–7th—first to seventh post cloacal papillae; a—amphid; ad—ad cloacal papillae; ba—body alae; dl—dorsal lip; lvl—latero ventral lip; pre—pre cloacal papillae; u—unpaired pre cloacal papillae).