Syphacia dewiae, Smales, 2020

Smales, Lesley, 2020, Gastrointestinal nematodes of Paramelomys levipes and P. mollis (Rodentia Muridae) from Papua, Indonesia and Papua New Guinea with the descriptions of three new genera and nine new species (Nematoda), Zootaxa 4861 (4), pp. 544-572 : 548-551

Syphacia dewiae n. sp.

( Figs 1 A– O)

Type host. Paramelomys mollis (Thomas) .

Site in host. Caecum and colon.

Type specimens. Holotype male, allotype female, paratypes 4 males, 50 females, BBM NG 102174A from Paramelomys mollis from southeast slopes, Mt Giluwe , 2300 m, Southern Highlands Province, Papua New Guinea; coll. A.B. Mirza 25. ii. 1973.

Other material examined. From Paramelomys mollis Papua New Guinea, Southern Province ; 10 males, 160 females, Southeast slopes, Mt Giluwe, 2300 m, BBM NG 102171 ; 102225.

Etymology. The species name is in recognition of the contribution of Dr Kartika Dewi to our understanding of the Oxyuridae .

Description. General: Mouth opening surrounded by 3 well-defined lips, 1 dorsal, 2 subventral. Cephalic plate oval, extended laterally with dorso-ventral constrictions; 4 cephalic papillae, 2 dorsal, 2 ventral; 2 amphids placed laterally between cephalic papillae at edge of cephalic plate. Cephalic vesicle present, cervical and lateral alae present in both sexes. Deirids not seen. Oesophagus with pharynx, corpus and posterior bulb.

Male: (measurements of 10 specimens) Body length 2.4–3.0 (2.6) mm, width 115–148 (121). Distance between amphids 45. Oesophagus total length 247–380 (286); bulb 66–90 (77) long. Nerve ring 112–165 (135), excretory pore posterior to oesophago-intestinal junction 396–620 (495) from anterior end. Mamelons, 3, well developed with transverse striations, on ventral posterior body; from anterior end to anterior mamelon 850–1200 (928), from anterior mamelon to middle mamelon 50–250 (145), middle mamelon to posterior mamelon 260–500 (278); mamelons 80–130 (90) long. Posterior extremity curled ventrally. Spicule filiform 82–102 (95) long; gubernaculum hook shaped 40.8–51.6 (46.5) long; accessory piece slender, unornamented 6.8–10.2 (8.5) long. Caudal papillae in 4 pairs; 1 pair pre-cloacal, 2 pairs ad-cloacal, 1 pair large caudal. Tail 250–390 (316) long.

Female: (measurements of 15 specimens) Body length 6.2–8.6 (7.5) mm, width 262–460 (361). Distance between amphids 85. Oesophagus total length 415–544 (482); bulb 102–155 (114) long. Nerve ring 192–231 (211), excretory pore posterior to oesophageal junction, 623–864 (725) from anterior end. Vulva salient, without ornamentation 1105–1750 (1284) from anterior end. Tail 1010–1400 (1093) long. Eggs oval, asymmetrical, smooth shelled, operculate, 79.5–85.8 (82.5) long 33.0–39.6 (35.8) wide.

Remarks. This new species belongs in the genus Syphacia Seurat , subgenus Syphacia Hugot because it possesses the suite of characters, including 3 mamelons, proposed by Hugot (1988) to distinguish the group. Following the key to the species of Syphacia occurring in the Sahul region of Dewi et al. (2014) Syphacia (Syphacia) dewiae n. sp. falls within a group of species having an oval, laterally extended, cephalic plate with a dorso-ventral constriction. Of these species S. (S.) dewiae comes closest to S. (S.) coccymyos in having both cervical and lateral alae. However, the lateral alae of S. (S.) dewiae are smooth not irregularly lobed as is found in S. (S.) coccymyos . Moreover S. (S.) dewiae is a larger worm, females up to 8.6 mm long compared with 5.1 mm, the female tail is longer, up to 1400 compared with 890 and the spicule is longer 82–102 compared with 61–77 for S. (S.) coccymyos . The other 4 species listed in the key and described from New Guinean murids differ from S. (S.) dewiae as follows: S. (S.) australasiensis has a square cephalic plate, S. (S.) longacauda has an oval cephalic plate, and S (S.) mamelonitenuis and S. (S.) lorentzymyos have round cephalic plates. Similarly, S. (S.) niobe , described since the key of Dewi et al. (2014) was prepared, differs from S. (S.) dewiae in having a round cephalic plate. Comparative measurements are given in Table 3 .

Syphacia (S.) ohtaorum Hasegawa, 1991 occurring in Mus caroli on Okinawa Island, Japan also has a laterally extended oval cephalic plate with a dorso-ventral constriction and 33 (male), 45–50 (female), between the amphids. However, S. (S.) ohtaorum has no cervical alae, the lateral alae are vesicular in males, mamelons 600 from the anterior end compared with 850–1200 and shorter spicules 54–64 compared with 82–102 for S. (S.) dewiae (see Hasegawa 1991). Syphacia (S.) dewiae is described from P. mollis , S. (S.) australasiensis from Rattus leucopus (Gray) and R. steini (Rummler) , S. darwini from Melomys lutillus (Thomas) , S. (S.) longacauda from Melomys rufescens (Alston) , Paramelomys moncktoni (Thomas) , P. lorentzii (Jentink) and P. rubex (Thomas) , S (S.) mamelonitenuis and S. (S.) lorentzymyos from Lorentzimys nouhuysi Jentink , S. (S.) coccymyos from Coccymys ruemmleri (Tate & Archbold) and S. (S.) niobe from Rattus niobe (Thomas) , and R. verucundus (Thomas) (see Smales 2001, 2004, 2005, 2009, 2010, 2011, 2016, 2017, 2018a, b; Smales & Heinrich 2010).

Syphacia sp., females only, were found in 7 individuals of P. mollis from the southeast slopes of Mount Giluwe at 2300 m, Southern Highlands Province coll A. B. Mirza between 2. ii. 1973 and 25. ii. 1973, BBM 97782A, NG 102172, 102173, 102235, 109369, 109374, 109375.Although females of the genus Syphacia are difficult to identify reliably to species these females demonstrated the characteristics of S. (S.) dewiae and were, most likely, also S. (S.) dewiae .

Figures

FIGURE 1 A–O. Syphacia dewiae sp. n. A. Male, lateral view; B. Male, en face view; C. Female, en face view; D. Female, anterior end; E. Male, cephalic end lateral view: F. Female, cephalic end lateral view; G. Male, cephalic end dorso-ventral view; H. Male, transverse section anterior end showing cervical alae. I. Female, cephalic end dorso-ventral view; J. Female, transverse section lateral ala; K. Male, posterior end lateral view; L. Male, lateral ala; M. Male, posterior end ventral view; N. Female, excretory pore (anteriorly) and vulva (posteriorly) lateral view; O. Female, tail lateral view. Scale bars in µm: A. O, 200; D, N, 100; K, M, 50; B, C, E, F, G, H, I, J, L, 25.