Alitta virens (Sars, 1835)

Villaloвos-Guerrero, Tulio F. & Вakken, Torkild, 2018, Revision of the Alitta virens species complex (Annelida: Nereididae) from the North Pacific Ocean, Zootaxa 4483 (2), pp. 201-257 : 249

Key to epitokal forms of Alitta virens species complex

Females

1 Pre-natatory region with 50–51 chaetigers ( Fig. 12A ); lamellae of neuropodial postchaetal lobe and cirrophore of ventral cirri greatly expanded ( Fig. 13E–G ); upper lobe of dorsal ligule distally enlarged, tongue-shaped ( Fig. 13F ); neuropodia with ensiform chaetae in both fascicles; secondary flap beneath neuropodial postchaetal lobe present ( Figs 1D , 13F, G )................................................................... A. plenidentata ( Moore, 1909) n. comb. California, USA

- Pre-natatory region with 36–38 chaetigers ( Fig. 18A ); lamellae of neuropodial postchaetal lobe and cirrophore of ventral cirri barely expanded ( Fig. 18G–I ); upper lobe of dorsal ligule not enlarged, blunt ( Fig. 18G–I ); neuropodia with ensiform chaetae only in subacicular fascicle; secondary flap beneath neuropodial postchaetal lobe absent............................................................................................... A. williami nom. nov. NW Canada and USA

Figures

FIGURE 1. Schematic diagrams and terminology of atokal and epitokal parapodial features in Alitta virens species complex; line drawings from medial parapodia in frontal view. Atoke parapodia: A. Lectotype of A. williami nom. nov. (NHMUK 1860.2.29.6). B. Lectotype of A. plenidentata n. comb. (CASIZ 14013). Epitoke parapodia: C. Holotype of A. brandti, male (ZINRAS 6/9181). D. Topotype of A. plenidentata n. comb., female (LACM-AHF Poly 9321). Ensiform chaetae omitted. Terminology based on Hylleberg et al. (1986) and Bakken & Wilson (2005), but with some adaptations.

FIGURE 12. Alitta plenidentata (Moore, 1909), epitoke female. Topotype (LACM-AHF Poly 9321), San Diego, California. A. Entire body, dorsal view. B. Left jaw, dorsal (left) and ventral (right) views. C. Pharynx, ventral view (roman numerals refer to pharyngeal areas; a, left; b, right); Area II hided by jaws; Area III barely seen. D. Root of aciculae (set. 60). E, F. Ensiform notochaeta, median (left) and lower (right) portions (set. 204). G, H. Heterogomph falcigers of neuropodial subacicular fascicle, upper (left) and median (right) portions (set. 16). I. Heterogomph spiniger, same chaetiger and fascicle. Arrows: A, white, pointing first natatory chaetiger. Scale bars: A, 10 mm; B, 5 mm; C, 2 mm; D, 1 mm; E–I, 10 µm.

FIGURE 13. Alitta plenidentata (Moore, 1909), epitoke female. Topotype (LACM-AHF Poly 9321), San Diego, California. A–G. Parapodia, posterior (left) and anterior (right) views (numbers refer to the chaetiger). H. Anterior segments, ventral view. Arrows: C, orange, superior lobe; white, inferior lobe. D, white, prechaetal lobe. F, white, postchaetal secondary flap; orange, flap of upper lobe; black, inferior lobe. G, white, postchaetal secondary flap; black, ova. H, first swollen ventral end of segment. Scale bars: A–G, 2 mm; H, 10 mm.

FIGURE 18. Alitta williami nom. nov., epitoke female. Topotype (USNM 27917), San Juan Archipelago, Washington, USA. A. Anterior region, dorsal view (arrow pointing first natatory chaetiger). B. Prostomium and anterior chaetigers, dorsal view. C. Left jaw, dorsal (left) and ventral (right) views. D–J. Parapodia, posterior (left) and anterior (right) views (numbers refer to the chaetiger). K. Posterior region, dorsal view. Arrows: D, black, superior lobe; white, inferior lobe. G, black, postchaetal lobe; white, prechaetal lobe. H, white, inferior lobe. I, J, white, ova. Scale bars: A–C, K, 5 mm; D, 1 mm; E–J, 2 mm.