Gendria sanghaensis, Moravec & Jirků, 2017

Moravec, František & Jirků, Miloslav, 2017, Some nematodes from freshwater fishes in central Africa, Folia Parasitologica (033) 64, pp. 1-39 : 17-20

Gendria sanghaensis sp. n.

Figs. 13–15

ZooBank number for species:

urn:lsid:zoobank.org:act:E8A7CB6C-43BD-4070-AA25-3D3156043085

Description. Medium-sized, whitish nematodes with bulbous cephalic region and smooth cuticle. Cephalic vesicle well developed ( Figs. 13A–C , 14D ). Oral opening almost oval, surrounded by 6 (2 dorsolateral, 2 ventrolateral and 2 lateral) slightly outlined cuticular lobes giving hexagonal appearance of mouth in apical view; these lip-like formations are continuous posteriorly with cephalic vesicle ( Figs. 13A–D , 14A,B ). Oral aperture surrounded by 8 submedian cephalic papillae arranged in 2 circles, each formed by 4 papillae, and 2 small lateral papilla-like amphids; papillae of inner circle distinctly smaller than those of outer circle ( Figs. 13D , 14A,B ). Anterior edge of proper oral aperture internally with row of small denticles ( Figs. 13D , 14C ). Mouth depressed, buccal cavity with 3 conical teeth ( Figs. 13A–D , 14B ). Oesophagus at level of nerve ring subdivided into anterior muscular portion and posterior muscular-glandular portion opening into intestine through large valve; anterior half of anterior portion of oesophagus somewhat expanded; posterior portion of oesophagus expanding posteriorly ( Fig. 13A–C ). Nerve ring approximately at mid-length of oesophagus, small deirids situated far posterior to posterior end of oesophagus. Excretory pore located short distance posterior to level of deirids ( Figs. 13A , 14D,E ). Tail conical, pointed.

Male (two specimens; holotype; measurements of paratype in parentheses). Length of body 14.7 mm (15.2 mm), maximum width 326 (340). Cephalic vesicle 165 (120) long and 129 (120) wide. Lip-like formations 12 (15) high. Oesophageal teeth in buccal cavity 6 (6–9) high. Oesophagus 517 (503) long; its anterior portion anterior to nerve ring 204 (240) long and 109 (93) wide; posterior expanded portion posterior to nerve ring 272 (243) long and 122 (129) wide; minimum width of oesophagus 57 (72). Nerve ring, deirids and excretory pore 245 (299), 830 (789) and 870 (830), respectively, from anterior end of body. Posterior end of body ventrally curved, provided with ventral sucker located 734 (843) anterior to cloaca ( Fig. 13F ). Spicules alate, equal, 438 (414) long; withdrawn spicules reach approximately to mid-way between cloaca and ventral sucker ( Fig. 13F ). Gubernaculum 54 (57) long. Preanal papillae: 6 subventral pairs and 1 median ventral papilla located short distance anterior to cloaca ( Figs. 13F , 15A,B ). Postanal papillae: 6 pairs (4 subventral and 2 lateral); small lateral phasmids located between lateral postanal papillae ( Figs. 13F , 15A ). Tail conical, pointed, 201 (180) long.

Female (two gravid specimens; allotype; measurements of paratype in parentheses). Length of body 21.5 mm (17.9 mm), maximum width 490 (435). Cephalic vesicle 174 (180) long and 174 (174) wide. Lip-like formations 18 (18) high. Oesophageal teeth in buccal cavity 9 (9) high. Oesophagus 558 (558) long; its anterior portion anterior to nerve ring 233 (228) long and 123 (123) wide; posterior expanded portion posterior to nerve ring 300 (300) long and 159 (120) wide; minimum width of oesophagus 87 (81). Nerve ring, deirids and excretory pore 256 (272), 1,034 (1,061) and 1,156 (1,170), respectively, from anterior end of body. Uteri opposed. Vulva situated 13.8 mm (11.2 mm) from anterior extremity, at 64% (62%) of body length. Vulval lips not elevated, with distinctly transversely striated cuticule ( Fig. 13H ). Vagina short, directed anteriorly from vulva. Uterus filled with many eggs. Eggs irregularly oval, thin-walled, size 51–63 × 42–51 (60–66 × 45–51), with content uncleaved or rarely cleaved into two blastomeres ( Fig. 13G ). Tail conical, 394 (225) long ( Figs. 13E , 14F ).

Type host: Shoulderspot catfish Schilbe marmoratus Boulenger ( Siluriformes : Schilbeidae ).

Site of infection: Intestine.

Type locality: Sangha River adjacent to Sangha Lodge, 02°59'06''N; 16°13'59''E (Congo basin), DSPA, Central African Republic (collected 12 September 2012) .

Prevalence and intensity: 1 fish infected/4 fish examined; 5 nematodes (only four specimens analysed morphologically).

Deposition of type specimens: IPCAS N-1133 (holotype and allotype) .

Etymology: The name sanghaensis relates to the type locality of this nematode species, i.e. the Sangha River.

Remarks. By the length of spicules, G. sanghaensis sp. n. resembles only G. tilapiae from African cichlids (spicules 410–490 µm long) and G. ranarum Karve, 1944 from amphibians in India (spicules 330–570 µm) (the latter designated as species inquirenda by Baker 1987); spicules of all other congeneric species (except for G. longispiculata sp. n.), as well as those of Buckleynema spp. , are distinctly shorter. However, in contrast to the new species, G. tilapiae has a circular oral aperture without lip-like structures (vs oral aperture hexagonal, with lip-like structures), the posterior portion of the oesophagus is moderately expanded (vs markedly expanded) and the body is distinctly shorter (the body length of males 7–8 mm, of females 7.7–11.5 mm vs males 14.7–15.2 mm, females 17.9–21.5 mm), whereas G. ranarum possesses lateral cervical alae (vs lateral alae absent), nine (vs six) pairs of preanal papillae and deirids are located at the level of the posterior end of the oesophagus (vs far posterior to the oesophagus end).

Figures

Fig. 13. Gendria sanghaensis sp. n. from Schilbe marmoratus Boulenger. A – anterior end of female, sublateral view; B – same, enlarged; C, D – cephalic end of female, lateral and apical views, respectively; E – tail of female, lateral view; F – posterior end of male, lateral view; G – egg; H – vulva, lateral view.

Fig. 14. Gendria sanghaensis sp. n. from Schilbe marmoratus Boulenger, scanning electron micrographs. A, B – cephalic end of male, subapical and apical views (arrow indicates protruding oesophageal tooth); C – row of denticles in mouth, ventral view; D – anterior end of male, ventral view (arrow indicates deirid); E – deirid; F – tail of female, lateral view. Abbreviations: a – amphid; b – two submedian cephalic papillae; c – cephalic vesicle; e – phasmid; f – anus.

Fig. 15. Gendria sanghaensis sp. n. from Schilbe marmoratus Boulenger, scanning electron micrographs. A – tail of male, ventrolateral view (arrow indicates phasmid); B – median precloacal papilla. Abbreviation: e – cloacal aperture.