Orientatractis matosi Jesus, Oliveira and Melo, 2023

Jesus, Ronald Ferreira, Oliveira, Sara Caroline Gama, Ramos, Isabel Mercedes Centeno & Melo, Francisco Tiago Vasconcelos, 2023, A new species of Orientatractis (Nematoda: Cosmocercoidea: Atractidae) parasite of Yellow-Spotted Amazon River Turtle, Podocnemis unifilis Troschel, 1848 (Testudines: Podocnemididae) in Brazilian Amazon, International Journal for Parasitology: Parasites and Wildlife 22, pp. 108-112 : 109-111

Orientatractis matosi Jesus, Oliveira and Melo n. sp. ( Figs. 1 and

2 )

Type host: Podocnemis unifilis Troschel, 1848 (Chelonia: Testudinae)

Type-locality: Tocantins River (3 ◦ 45′44.3″S, 49 ◦ 39′44.1″W), Tucuruí, Par´a, Brazil .

Other localities: Xingu River , (2 ◦ 41′3.901″S, 52 ◦ 0′42.379″W), Senador Jose´Porfírio, Par´a, Brazil .

Site of infection: Stomach and large intestine.

Prevalence: 100% (3 infected/3 examined)

Type-specimens: Holotype ( CHIOC 39301 a), allotype ( CHIOC 39301 b) and 38 paratypes ( CHIOC 39302 a - 39302b) deposited in the Helminthological Collection of Oswaldo Cruz Institute - Rio de Janeiro, Brazil.

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ZooBank registration: To comply with the regulations set out in article 8.5 of the amended 2012 version of the International Code of Zoological Nomenclature ( ICZN, 2012), details of the new species have been submitted to ZooBank. The Life Science Identifier ( LSID) for Orientatractis matosi n. sp. is urn:lsid:zoobank.org:act:623D54BF-3023-4864-9849-F884EC0B3E38

Etymology: The specific epithet is given in honor of Professor Edilson Rodrigues Matos from the Federal Rural University of Amazonia, Brazil, in recognition of his valuable contributions to our knowledge of the parasites of aquatic animals in the Amazon.

3.2. Description

General. Small and slender nematodes, tapering anteriorly. Lateral alae absent. Cuticle finely transversely striated. Males and females similar in length ( Fig. 1A and D ). Oral aperture hexagonal, with six lips fused, surrounded by four submedian papillae in one circle. Four submedian lips (two subdorsal and two subventral) and two lateral lips supporting large amphids. Each submedian lip bearing a chitinoid piece formed by two well-sclerotized, recurved pointed spines connected at their base and a single large median spine, lateral lips with two small spines posterior to each amphidial pore ( Fig. 1B and 2A ). Esophagus divided into three parts; anterior esophagus (corpus), posterior esophagus (isthmus) and valved bulb. Nerve ring formed by numerous nerve fibers, some connected by nervous cells distributed from mid-length of esophagus to beginning of isthmus. Deirids small, lappet-like in shape, somewhat posterior to nerve ring level; excretory pore large, surrounded by cuticular striations, anterior to esophageal bulb ( Fig. 1E and 2B ). Tail long and sharply pointed ( Fig. 1A, C, D and G ).

Male [Based on holotype and 19 paratypes; all adult males] Total length

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2.30 (2.30–2.58) mm, width at esophago-intestinal junction 65 (48–69). Entire esophagus 369 (353–391) long. Corpus 138 (131–149) long; isthmus and esophageal bulb 231 (213–242) long. Width of bulb 45 (38–52). Nerve ring, excretory pore, and deirids 138 (143–164), 286 (277–303), and 205 (195–227), respectively, from anterior end of body. Nine pairs of caudal papillae: four subventral precloacal pairs forming a group of papillae close to each other, and five postcloacal pairs (first subventral, second ventrolateral, third subventral, fourth subventral and fifth dorsolateral). Unpaired papilla on anterior cloacal lip absent. Phasmids lateral, located between second and third pairs of postcloacal papillae at 179 (177–209) from posterior end ( Fig. 1G and 2D ). Spicules unequal in size, lanceolate, with transverse striations, proximal ends slightly expanded, distal ends sharply pointed, larger (left) spicule 108 (101–126) long, smaller (right) spicule 37 (33–40) long; gubernaculum with proximal end slightly expanded, distal end pointed, 31 (28–33) long ( Fig. 1F ). Tail 261 (271–300) long.

Female [Based on allotype and 19 paratypes; all adult females with well developed larvae in uterus] Total length 2.54 (2.41–2.70) mm, width at esophago-intestinal junction 61 (51–70). Entire esophagus 382 (353–387) long. Corpus 143 (130–152) long; isthmus and esophageal bulb 239 (217–245) long. Width of bulb 48 (40–52). Nerve ring, excretory pore, and deirids 160 (147–166), 304 (274–317), and 210 (200–225), respectively, from anterior end of body. Vulva close to anus, 447 (381–515) from posterior end of body; distance anus-vulva 57 (53–67) ( Fig. 1C and 2C ). Vagina short, muscular, directed anteriorly from vulva ( Fig. 1C ). Uterus monodelphic and prodelphic. Viviparous, larvae present, often filling uterus (larvae total length 0.94–1.13 mm based on four larvae measured in uterus of allotype). Phasmids located at 271 (235–339) from posterior end. Tail 388 (331–462) long.

Figures

Fig. 1. Line drawings of Orientatractis matosi n. sp. (A) Female, whole body, ventral view. (B) Female, cephalic extremity, apical view (C) Posterior end of female, lateral view. (D) Male, whole body, lateral view. (E) Anterior extremity of body, ventrolateral view. (F) Details of spicules and gubernaculum. (G) Male, posterior end, ventral view.

Fig. 2. Scanning electron micrographs of Orientatractis matosi n. sp. (A) Cephalic extremity, apical view (amphidial pores, arrowheads). (B) Anterior extremity of body, lateral view, lines indicate deirid and excretory pore. (C) Posterior extremity of female, ventrolateral view, lines indicate vulva and anus. (D) Posterior extremity of male, ventrolateral, distribution of caudal papillae (arrows) and phasmids (arrowheads). Abbreviations: anus, An; deirid, De; excretory pore, Ep; vulva, Vu; single large submedian spine, a; submedian pointed spines, b. Inset: Cephalic end details, ventrolateral view (Scale-bar: 5 μm), Detail of excretory pore (Scale-bar: 5 μm).