Thirty specimens of Propimelodus eigenmanni were collected from rio Parauaú, located in municipality of Breves (1°40'57''S, 50°28'51''W), state of Pará, eastern Brazilian Amazon (permission number SISBIO N 68028-4). Fish were collected from March to July 2018 with the aid of a cast net. Fish were transported alive to the laboratory for necropsy. In the laboratory, the organs were separated and placed in Petri dishes with saline solution NaCl 0.9% and examined using a stereomicroscope. The recovered nematodes were fixed in a solution of AFA (93 parts 70% ethyl alcohol, 5 parts formaldehyde, and 2 parts glacial acetic acid) and processed using light microscopy and scanning electron microscopy according to Pinheiro et al. (2018, 2020). Measurements are given in micrometers unless otherwise noted and are presented as the mean followed by the range (minimum and maximum values) in parentheses. The type material of the new species described here has been deposited in the Other Invertebrate collection of the Museu Paraense Emílio Goeldi (MPEG), municipality of Belém, Pará State, Brazil.
Camallanidae Railliet & Henry, 1915
Camallaninae Railliet & Henry, 1915
Spirocamallanus Olsen, 1952
Type species: Spirocamallanus spiralis Baylis, 1923
Spirocamallanus delirae sp. n. Ruffeil1, Giese & Pinheiro
(Based on light microscopy and scanning electron microscopy examination: Figures 1-2, and table 1)
Type-host: Propimelodus eigenmanni (Van der Stigchel 1946) (Siluriformes: Pimelodidae).
Site of infection: intestine
Host–parasite data: prevalence: 46.2%
Type-locality: Rio Parauaú, municipality of Breves (1°40'57''S, 50°28'51''W), state of Pará, Brazil - Biome: Amazon
Type-material: Holotype male (MPEG XX), allotype female (MPEG XX), and six paratypes (Males: MPEG XX; MPEG XX; MPEG XX; Females: MPEG XX; MPEG XX; MPEG XX) were deposited in the Coleção de Invertebrados of the Museu Paraense Emílio Goeldi (MPEG), municipality of Belém, Pará State, Brazil. (after acceptance of the manuscript)
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 Spirocamallanus delirae sp. n. is urn: lsid: zoobank.org:pub: XXXXX
Etymology: The specie is dedicated affectionately to Dra. Delir Corrêa Gomes Maués da Serra Freire, in recognition of her outstanding work on taxonomy of fish nematodes.
Description
General: Nematode of medium size compared with its congeners, reddish colored when alive and dark brown color when fixed; cuticle with delicate and fine transverse striations. Brown-orange buccal capsule, wider than long; well-developed basal ring (Fig. 1a). Serrated spiral ridges visible in lateral view of the inner surface of the buccal capsule (Figures 1b; 2a, b). Mouth aperture rectangular, surrounded by four flat, crescent-shaped elevations and eight submedian cephalic papillae arranged in two circles, each formed by four papillae. Papillae of external circle distinctly larger (Figs. 2a, b). Pair of small lateral amphids with two amphidial papillae (Fig. 2a). Muscular esophagus shorter than the glandular esophagus (Fig. 1a). Deirids are located between the buccal capsule and the nerve ring (Figs. 1a; 2c).
Males [based in holotype and 8 paratypes, measurements of the holotype in brackets] Body length 12mm (11–14mm) [14mm], maximum width at level of esophageal-intestinal junction 150 (133–187) [133]. Buccal capsule including basal ring 87 (83–95) [83] long; 57 (52–67) [55] wide; basal ring 14 (12–17) [13] long, 44 (38–48) [48] wide. Maximum width/length ratio of buccal capsule 1:0.7 (1:0.6–0.7) [1:0.66]. Number of spiral ridges between 15 and 18 [17]. Deirids, nerve ring and excretory pore positioned at 161 (128–197) [168], 247 (207–283) [207] and 360 (313–440) [313], respectively, from the cephalic extremity (Figs. 1a, 2c, d). Muscular esophagus width 607 (520–727) [560] × 58 (53–67) [53]. Glandular esophagus width 697 (567–847) [687] × 67 (60–73) [67]. Length of entire esophagus and buccal capsule representing 11% (9−13%) [9%] of body length. Posterior end of body ventrally curved, provided with wide caudal anteriorly interconnected alae, forming a pseudosucker, and not reaching tip of tail; bearing nine pairs of pedunculated papillae: 3 pairs of subventral pedunculate papillae, additional 2 pairs of small transversely elongate sessile ventral papillae surrounding cloaca and 6 pairs postcloacal (first pair subventral, second pair subventral internal, third pair lateral and fourth and fifth pairs dorsal, all pedunculate) (Figs. 1c; 2g, i). One pair of phasmids ventral at tip of tail (Fig. 2h). Spicules similar in shape and unequal in size, left spicule shorter, 280 (240–347) [273] long and right spicule 477 (427–573) [507] long. Gubernaculum absent. Tail conical, 186 (167–210) [200] long, with terminal spike; length of terminal spikes 9 (8–10) [8].
Females with eggs and larvae [based on allotype and 7 paratypes, measurements of allotype in brackets] body length 23mm (18–27 mm) [25mm]; maximum width at level of vulva 452 (400–527) [500]. Buccal capsule, including basal ring, 97 (78–107) [93.33] × 68 (60–83) [60] wide; basal ring 17 (15–22) [15] long, 48 (43–53) [50] wide. Maximum width/length ratio of buccal capsule 1:0.7 (1:0.62–0.83) [1:0.64]. Number of spiral ridges between 17 and 19 [19]. Deirids, nerve ring and excretory pore at 166 (143–187) [173], 240 (185–287) [217], and 372 (275–422) [408], respectively, from the cephalic extremity. Muscular esophagus 766 (600–893) [833] × 72 (66–80) [80]. Glandular esophagus 0.9mm (0.7–1mm) [0.773] × 86 (73–100) [87]. Length of entire esophagus and buccal capsule representing 4% (3–4%) [3.7%] of body length. Vulva pre-equatorial, 8mm (6–10mm) [7.63mm] from anterior extremity, at 36% (30–41%) [30%] of body length. Vulval lips not elevated (Fig. 2e). Vagina muscle directed posteriorly (Fig. 1d). Uterus filled with larvae 197 (155–222) long (based on 20 larvae) and eggs 23 (22–23) long by 20 (18–23) wide (based on 30 eggs). Tail rounded, with digit-like projection bearing two small terminal spikes (Figs. 1e; 2f). Length of entire tail 156 (133–190) [133]; digit-like projection with terminal spikes 31 (28–35) [30] long and 15 (13–18) [13] wide; spikes 10 and 12 [10] long.