Elzalia bifurcata, Sun & Huang, 2017

Elzalia bifurcata sp. nov.

( Fig. 1–2 View FIGURE 1 View FIGURE 2 )

Type material. Three males and two females were collected from Stations DH4-8, DH4-4, DH4-6 and DH5-4. Holotype: ♂1 on slide DH 12-4-8-4-3, paratypes: ♂2, ♂3, ♀1 and ♀2 on slides DH 12-4-8-4-3, DH 12- 4-6-2-5, DH 12-4-4-6 -2 and DH 12-5-4-3 -2, respectively.

Type locality and habitat. Sublittoral in the East China Sea. Station DH4-8: 125° 52.5´E, 27° 58΄ N, water depth 116 m, clay sediment; DH4-4: 124° 12.7´E, 28° 52.1΄ N, water depth 74 m, clay and sandy sediment; DH4- 6: 125° 2.4´E, 28° 25΄ N, water depth 101 m, muddy sediment; DH5-4: 123° 13´E, 27° 47.5΄ N, water depth 86 m, clay sediment.

Etymology. The species name refers to the structure of spicules with bifurcate distal ends.

Measurements. Table 1.

Description. Males. Body small, slender, with tapering anterior and posterior ends. Cuticle with very fine striations. Both subcephalic and somatic setae absent. Inner labial sensilla not visible. Six outer labial sensilla and four cephalic sensilla setiform, arranged in one circle. Outer labial setae 7 µm long and cephalic setae 6 µm long. Buccal cavity cylindrical, slightly cuticularised, 12–13 µm deep and 5 µm wide. Amphidial fovea circular, 8 µm wide, located at level of base of buccal cavity. Pharynx cylindrical, slightly swollen at base, not forming true posterior bulb. Cardia conical, projecting into the intestine. Nerve ring and secretory-excretory system not observed. Testes indistinct. Spicules paired, equal and elongated, strongly cephalated proximally and bifurcated (yshaped) distally, 4.8–5.3 cloacal body diameters long. Gubernaculum tubular, simple, without apophyses. Precloacal supplements absent. Tail 4.6–4.9 cloacal body diameters long, conico-cylindrical with a small terminal spinneret. Three contiguous caudal glands with common opening. Three terminal setae about 6 µm long.

Females. Similar to males in most aspects. Reproductive system monodelphic with a single anterior outstretched ovary, located to left of intestine, 140 µm long. Oviduct a short and wide tube. Uterus sac-like. Vagina conical. Vulva situated at about midbody.

Differential diagnosis and discussion. Elzalia bifurcata sp. nov. is characteriZed by elongated spicules with bifurcate distal ends, simple tubular gubernaculum without apophyses; relatively short body length (<680 µm); outer labial and cephalic sensilla 6–7 µm long. Elzalia bifurcata sp. nov. is close to E. striatitenuis Zhang and Zhang, 2006 and E. mediterranea Vitiello, 1970 in shor body length, spicule length and relatively simple gubernaculum. However, E. bifurcata sp. nov. differs from E. striatitenuis in having longer cephalic setae (6 µm vs 2.5 µm), deeper buccal cavity (12–13 µm vs 9–10 µm), spicules with bifurcate distal ends (vs tapered distally not bifurcate), tubular gubernaculum without apophyses (vs complex apophyses with four sections). E. bifurcata sp. nov. can be distinguished from E. mediterranea in having spicules with bifurcate distal ends (vs. tapered distal end not bifurcated in E. mediterranea ); absence of cervical setae (vs eight files of cervical setae present in E. mediterranea ); gubernaculum without apophysis (vs with a pair of slender apophyses in E. mediterranea ).

The genus Elzalia was established by Gerlach in 1957. Currently, nine valid species have been described from all around the world ( Hope & Aryuthaka 2009). These are Elzalia bipectinella Hope & Aryuthaka 2009 , E. federici Castillo-FernandeZ and Lambshead 1990, E. floresi Gerlach 1957 , E. gerlachi Zhang and Zhang 2006 , E. kimae Castillo-FernandeZ and Lambshead 1990; E. mediterranea Vitiello 1970 ; E. poli Castillo-FernandeZ and Lambshead 1990, E. striatitenuis Zhang and Zhang 2006 , E. tuberculata Hope & Aryuthaka 2009 , respectively.