Cervonema longispicula, Huang & Jia & Huang, 2018

Huang, Mian, Jia, Susu & Huang, Yong, 2018, One new species and one new record of the species of the family Comesomatidae (Nematoda: Chromadorida) from the South China Sea, Zootaxa 4504 (1), pp. 119-127 : 120-121

Cervonema longispicula sp. nov.

( Figs 1–2 )

Type material. Four males and one female were collected from Station NHqzhx1. Holotype: ♂ 1 on slide NH17-0- 2-64-3 (surface layer), paratypes: ♂ 2, ♂ 3, ♂ 4 and ♀ 1 on slides NH17-0- 2-64-1 (surface layer), NH17-0- 2-64-6 (surface layer), NH 17-2-5 -130-1 (subsurface layer) and NH17-0-2-148-1 (surface layer), respectively.

Type locality and habitat. Subtidal muddy sediment at Station NHqzhx1 of Qiongzhou strait (20°3′53″ N; 110°21′5″ E, water depth 13 m).

Etymology. The species name refers to its feature of elongated spicules.

Measurements. Table 1.

Description. Males. Body slender with elongated cervical region and filiform tail. Head 10–11 µm in diameter. Cuticle finely striated, more obvious in the cloacal or anus region. The inner labial sensilla indistinct, six outer labial sensilla and four cephalic sensilla setiform, stout, 5 µm long, about 50% of head diameter. Amphideal fovea multispiral with 4.5 turns, 10 µm in diameter (i.e. 63% of corresponding body diameter). Anterior border of amphids 16 µm behind the front end (i.e. 1.6 times of head diameter). Buccal cavity small. Pharynx cylindrical, accounting for about 17% of the body length, gradually expanded towards end, not forming bulb. Nerve ring surrounds the pharynx at 60 µm or 30% of its length from the anterior end. Ventral gland obvious, located just before the cardia. Secretory-excretory pore behind the never ring, at 95 µm from the anterior end. The cardia prominent, conical. Tail conical with a long filiform section, 198–270 µm long (i.e. 7.9–10.4 anal body diameters long). Tail tip enlarged, with a tubular spinneret. Three terminal setae present, 7 µm long. Three caudal glands arranged in tandem, confined entirely to the tail. Many caudal setae scattered throughout the tail, 4–5 µm long.

Reproductive system diorchic, testes opposed and outstretched, anterior testis to the left of intestine, posterior testis to the right of intestine. Spicules elongate, curved, cephalated proximal end, tapered distal end, 45–48 µm in length, (i.e. 1.6–1.9 anal body diameters long). Gubernaculum small with a dorsal hook-like apophysis. A short (4 µm long) precloacal seta present. No precloacal supplements were observed.

Female. Similar to males in most respects except the body size slightly larger and caudal setae lacking. Body length 1411 µm, maximum body width 35 µm. Reproductive system didelphic, two ovaries opposed and outstretched. Anterior ovary situated to the left of intestine, posterior ovary situated to the right of intestine. Ovaries short. Oviduct a wide tube. Mature eggs oblong. Two oval, sac-like spermathecae located on each side of each (anterior and posterior) gonoduct, filled with oval spermatozoa. Uterus a short tube. Vagina straight and broad. Vulva located just before the midbody (i.e. at 48% of total length), opening by a small pore at the body ventral side.

Differential diagnosis and discussion. Cervonema longispicula sp. nov. is characterized by short and stout cephalic setae, elongated and curved spicules, and presence of gubernaculum with hook-like dorsal apophysis that can easily differentiate the new species from the other eighteen known species of this genus. C. longispicula sp. nov. resembles C. pseudodeltensis Barnes, Kim & Lee, 2012 , C. tenuicauda (Schuurmans Stekhoven, 1950) Wieser, 1954 , C. gourbalti Muthumbi, Soetaert & Vincx, 1997 and C. macroamphis Jensen, 1979 in the size of body and amphideal fovea, the length of cephalic setae, but differs from them by the combination of its characteristics: stout cephalic setae; curved spicules with cephalate proximal end and more than one anal diameter in length; gubernaculum with hook-like dorsal apophysis. As for the spicules and anterior sensilla, the spicules of other known species in this genus are short, straight or slightly curved, and commonly less than one anal diameter in length, and the anterior sensilla are very slender.

Figures

FIGURE 1. Cervonema longispicula sp. nov. (A) lateral view of male anterior end, showing buccal cavity, cephalic setae and amphideal fovea; (B) entire view of male, showing two testes; (C) lateral view of male anterior end, showing pharynx and excretory system; (D) lateral view of male posterior end, showing spicule, gubernaculum and caudal glands; (E) lateral view of male cloacal region, showing spicule, gubernaculum and precloacal setae; (F) entire view of female, showing vulva, spermatheca, eggs and ovaries.

FIGURE 2. Cervonema longispicula sp. nov. (A) lateral view of female anterior end, showing buccal cavity and amphideal fovea; (B) lateral view of male anterior end, showing head sensilla and amphideal fovea; (C) lateral view of male posterior end; (D) lateral view of male cloacal region, showing spicules and gubernaculum. (Scales: A, B 10 µm; C, 30 µm; D 20 µm).