Trichuris mallomyos, Hasegawa, Hideo & Dewi, Kartika, 2017

Hasegawa, Hideo & Dewi, Kartika, 2017, Two new species of Trichuris (Nematoda: Trichuridae) collected from endemic murines of Indonesia, Zootaxa 4254 (1), pp. 127-135 : 130-132

Trichuris mallomyos sp. nov.

( Figs. 13–22 )

General. Usual size as a Trichuris in murids. Cuticle with fine transversal striation. Anterior part of body narrow, thread-like, tapering to cephalic end; posterior part of body stout ( Figs. 13 , 19 ). Minute cephalic stylet present. Stichosome with 1 row of stichocytes, and 1 pair of conspicuous cells at esophago-intestinal junction level ( Figs. 13 , 19 ). Nucleus of stichosome present per 4 to 5 subdivisions, in middle portion ( Fig. 14 ). Bacillary band commencing just after cephalic end, well developed in middle portion of anterior body ( Figs. 14, 15 ), becoming narrower and invisible anterior to esophago-intestinal junction. Round cuticular inflations of various sizes bordering bacillary band present in anterior portion of body.

Male (10 specimens): Length 28.8 (24.6–32.4) mm. Anterior portion of body 18.7 (15.3–21.0) mm long, corresponding to 65 (62–68) % of body length. Width at middle of anterior body 101 (95–111), esophago-intestinal junction 227 (202–259) and thick portion of posterior body 359 (331–397). Round cuticular inflations present in area from 258–370 to 1287–1990 from anterior end. Stichosome with ca. 180–200 nuclei. Testis recurved posterior to esophago-intestinal junction, directed posteriorly forming convolutions, ending near anterior end of proximal cloacal tube ( Fig. 13 ). Proximal cloacal tube stout, 2.53 (2.25–2.77) mm long, united laterally to distal cloacal tube of 0.92 (0.75–1.37) mm long ( Fig. 13 ). Spicular pouch 0.28 (0.09–0.73) mm long ( Fig. 13 ). Spicule length 2.89 (2.75–3.13) mm long, corresponding to 10.1 (8.5–11.9) % of body length, sharply pointed distally ( Figs. 16–18 ).

Distal portion of spicule with pit-like structures on one side ( Fig. 17 ). Spicular sheath densely spinose; distal end of fully extended spicular sheath devoid of spines, with reticulate markings ( Fig. 18 ). Cloaca subterminal with 1 pair of simple papillae ( Fig. 16 ).

Female (10 specimens): Length 35.1 (28.1–41.4) mm. Anterior body 22.0 (17.2–27.1) mm long, corresponding to 62.6 (59.6–66.9) % of body length. Width at middle of anterior body 100 (86–109), esophagointestinal junction 243 (202–274) and thick portion of posterior body 420 (372–486). Round cuticular inflations present in area from 198–455 to 1505–2109 from anterior end. Stichosome with ca. 190–210 nuclei. Vulva slightly elevated, 81 (0–137) posterior to esophago-intestinal junction ( Fig. 20 ). Vagina muscular, winding posteriorly, 1.37 (1.01–1.65) mm long ( Fig. 21 ). Ovary extending to preanal level ( Figs. 19, 21 ). Anus subterminal ( Fig. 20 ). Eggs lemon-shaped, thick shelled, brownish, with polar plugs, 90.1 ± SD 2.9 (83–95) by 39.2 ± SD 1.2 (36–41) (n=50) ( Fig. 22 ).

Taxonomic summary.

Type host: Mallomys rothschildi Thomas, 1898 (Rothschild’s woolly rat) (Hydromini: Murinae : Muridae ).

Site in host: Cecum.

Type locality: Highland forest near Wamena (4˚11’S, 138˚58’E; 1500 m elevation), Papua Indonesia, Indonesia .

Date of collection: 4 August 1993.

Type specimens: USNM 1422105 (hototype male and allotype female), USNM 1422106 (6 male and 6 female paratypes), MZB Na 721 (3 male and 3 female paratypes).

Coparasites: Odilia mallomyos Hasegawa & Syafruddin, 1994 (Nematoda: Heligmonellidae ) ( Hasegawa & Syafruddin, 1994).

Symbiotypes: AMNH M-267742, M-267743.

Etymology. Species epithet is derived from the generic name of the type host.

Remarks. This species is also assigned to Trichuris for the same reasons as for the preceding species. By having a gradually tapered and sharply pointed spicule, it resembles T. musseri , T. petrowi and T. spalacis among those parasitic in murids ( Petrov & Potekhina, 1953; Skrjabin et al., 1957). It is easily distinguished from T. musseri in that the body is much larger and the number of nuclei per divisions of stichosome is fewer. It also differs from the latter two species by the following features: T. petrowi has a cephalic expansion and a larger ratio of anterior body to worm length (>70 %) in male, and much longer distance (> 1 mm) between the anus and posterior end of body in female; T. spalacis has a smaller ratio of anterior body to worm length (<60 %) in both sexes and much smaller eggs (62–65 by 29 µm) ( Petrov & Potekhina, 1953; Skrjabin et al., 1957). Morphology of the distal end of the spicule has not been described or figured in some Trichuris species in murids, namely, T. neotomae Chandler, 1945 and T. peromysci Chandler, 1946 . Although their males have body length comparable to the present males (22–23 mm in T. neotomae and 14.7–31.8 mm in T. peromysci ), they possess a much shorter spicule (1.15– 1.23 mm and 0.86–1.4 mm long, respectively), being readily distinguished from T. mallomyos sp. nov. ( Chandler, 1945, 1946). Trichuris germani , an endemic congener parasitic in the endemic murids of Papua New Guinea, differs from the present species by having smaller eggs (42.5–63 by 25.5–27.7 µm) in addition to the rounded distal end of the spicule ( Smales, 2013).

Figures

FIGURES 13 – 18. Male of Trichuris mallomyos sp. nov. collected from Mallomys rothschildi in Papua, Indonesia. 13. Holotype. 14. Middle portion of stichosome showing bacillary band at left side. 15. Enlarged view at middle showing surface of bacillary band partially; two-way arrow indicating width of bacillary band at this level. 16. Caudal end. 17. Distal end of spicule; arrows showing pit-like structures. 18. Distal end of spicular sheath fully extended.

FIGURES 19 – 22. Female of Trichuris musseri sp. nov. collected from Mallomys rothschildi in Papua Indonesia. 19. Allotype. 20. Esopahgo-intestinal junction. 21. Caudal end. 22. Egg.