Paragnomoxyala macrostoma ( Huang & Xu, 2013 ) Sun & Huang, 2017

Sun, Yan & Huang, Yong, 2017, One new species and one new combination of the family Xyalidae (Nematoda: Monhysterida) from the East China Sea, Zootaxa 4306 (3), pp. 401-410 : 406-409

Paragnomoxyala macrostoma ( Huang & Xu, 2013) comb. nov.

( Fig. 3–4 )

Material. Five males and three females were collected from Stations DH3–1. ♂1 on slide DH 12-3-1-3 -1; ♂2, ♂3, ♂4, ♂5, ♀1, ♀2 and ♀3 on slides DH 12-3-1-1-2, DH 12-31-4-1, DH 12-3-1-2-4, respectively.

Specimens locality and habitat. Sublittoral in the East China Sea. Station DH3–1: 122° 30.1´E, 30° 0΄ N, water depth 21 m, clay sediment.

Measurements. Table 2.

Description. Males. Body slender, gradually tapering towards both extremities. Cuticle with coarse annular striations, beginning at base of buccal cavity and ending at tail tip. Outer labial sensilla papilliform, inner labial sensilla not observed, four cephalic sensilla setiform, 3–4 µm long. Short somatic setae scattered over body. Lips elongated and tapering distally. Buccal cavity large, funnel-shaped, 16 µm long and 15 µm wide, consists of cheilostom and conical pharyngostom. Amphidial fovea circular, 8 µm in diameter (36% of corresponding body diameter), situated at 15 µm from anterior end. Secretory-excretory system not observed. Pharynx cylindrical. Cardia well developed, conical, 11 µm long. Nerve ring located at 45% of pharyngeal length. Spicules 26–30 µm long, slender with slightly curved proximal ends and hooked distal ends. Gubernaculum absent. No precloacal supplements. Tail conico-cylindrical, 5.1–5.5 cloacal body diameter long, tapering, with distal fourth cylindrical and three short terminal setae. Three caudal glands with common opening. Spinneret not observed.

Females. Females have most features in common with males, but are slightly larger. A single anterior outstretched ovary 570 µm long. Oviduct a wide tube. Uterus extended backwards, wide tube, containing round eggs. Vagina straight, 0.4 times vulval body diameter. Vulva posterior to mid-body.

Diagnosis and discussion. Daptonema macrostoma was described from the yellow Sea by Huang and Xu (2013). It is characteriZed by large funnel-shaped buccal cavity with weakly cuticulariZed walls; outer labial sensilla papilliform; four cephalic sensilla setiform; spicules almost straight, gubernaculum absent. However, since above listed characters fit well with the genus Paragnomoxyala , and considering the fact that Daptonema macrostoma does not have typical features of Daptonema , such as conical buccal cavity, 6–10 outer labial setiform sensilla, gubernaculum present, we think that the species ought to belong to the genus Paragnomoxyala . Therefore, we transfer this species to Paragnomoxyala , and name it as Paragnomoxyala macrostoma ( Huang and Xu, 2013) comb. nov. Paragnomoxyala macrostoma differs from the only other species of the genus, Paragnomoxyala breviseta Jiang & Huang, 2015 , in shape of buccal cavity and structure of spicules: Paragnomoxyala macrostoma has broader head (>17 µm vs <15 µm in P. breviseta ); funnel shaped buccal cavity (vs rectangular buccal cavity in P. breviseta ); spicules with hooked distal ends (vs blunt distal ends in P. breviseta ).

This work was supported by National Natural Science Foundation of China (No: 41176107). We are very thankful to all crew members of R/V “Science 3” for their kind help in samples collection. We are sincerely grateful to Dr Zhang Yan (Agricultural University of Qingdao) for providing related references, Dr Liu Xiaoshou (Ocean University of China) for linguistic assistance and two anonymous referees for providing valuable suggestions and criticisms.

Figures

FIGURE 3. Paragnomoxyala macrostoma (Huang & Xu, 2013) comb. nov. (A) lateral vIeW of male anterIor end, shoWIng buCCal CavIty, amphId and pharynX; (B) entIre vIeW of female, shoWIng vulva, ovary and eggs; (C) lateral vIeW of male posterIor end, shoWIng spICule and Caudal glands; (D) lateral vIeW of male head, shoWIng buCCal CavIty and CephalIC setae; (E) lateral vIeW of male CloaCal regIon, shoWIng spICule.

FIGURE 4. Paragnomoxyala macrostoma (Huang & Xu, 2013) comb. nov. (A) lateral vIeW of female anterIor end; (B) lateral vIeW of male anterIor end; (C) lateral vIeW of male posterIor end; (D) lateral vIeW of male CloaCal regIon (From Huang & Xu, 2013).