Graphonema antarcticum Shimada & Tsujimoto & Watanabe 2019, sp. nov.

• Main Authors: Shimada, Daisuke, Tsujimoto, Megumu, Watanabe, Kentaro
• Format: Other/Unknown Material
• Language: unknown
• Published: 2019
• Subjects: Biodiversity; Taxonomy; Animalia; Nematoda; Adenophorea; Desmodorida; Chromadoridae; Graphonema; Graphonema antarcticum; Lützow-Holm Bay; Syowa Station; Antarc*; Antarctica
• Online Access: https://zenodo.org/record/4734605; https://doi.org/10.5281/zenodo.4734605

Graphonema antarcticum sp. nov. (Figs 1–4; Table 1) Material examined. Holotype: adult male (ICHUM 5867), whole mount, 68°59′55″S, 39°35′28″E, Kita-noura, off Syowa Station in Lützow-Holm Bay, Antarctica, surface of macroalgae collected by means of bait traps at 27 m depth, 16 December 2005. Paratypes: six adult males (ICHUM 5868–5872, 5876) and five adult females (ICHUM 5873–5875, 5877, 5878), whole mounts, same collection data as with holotype. Non-type: an adult male (ICHUM 5879), Au-coated SEM specimen, same collection data as with holotype. Diagnosis. Graphonema antarcticum sp. nov. is characterized by large body size (equal to or more than 2.0 mm), truncated cephalic end, presence of lateral differentiation, long spicules (80–90 µm and 1.3–1.6 abd), without capitulum, well-developed gubernaculum with L-shaped lateral pieces bending at an obtuse angle with minute denticles at distal end, and long tail in both sexes (approximately 4–6 abd in males and 6–9 abd in females). Measurements. See Table 1. Description. Males. Body (Fig. 1A) almost cylindrical, tapering toward both ends. Epicuticle coarsely annulated (Fig. 2), except at anterior and posterior body ends (Figs. 1B, 2, 4A, G). Exocuticle with heterogeneous ornamentations (cf. Gourbault and Vincx 1994): tiny punctate at anterior half of cephalic region (Figs 1B, 4A); regularly hexagonal to posterior half of cephalic region to anterior 1/3 of pharynx (Figs 1B, C, 4A, B); longitudinally elongated hexagonal from anterior 1/3 of pharynx to cloacal region (Figs 1D, E, 4C, D), becoming longer toward posterior end; regularly hexagonal in caudal region (Figs 1F, 4F), becoming smaller toward posterior end; no ornamentation at tail end (Figs 3A, 4G). Lateral differentiation (Figs 1 C–E, 4B, C) present, beginning from anterior 1/3 of pharyngeal region to cloacal region, becoming wider toward posterior end. Cephalic region (Figs 1B, G, H, 2A, B) not set-off, truncated at anterior end. Cephalic diameter 25–30% of mbd. Inner labial sensilla inconspicuous. Six outer ...