Y-nauplius Type AC

Figs 2, 9F–H

Type AC – Dreyer et al. 2023a: figs 4, 5a, c, tables s1–s2.

Material examined

JAPAN – Okinawa, Sesoko I., laboratory pier, 26°38ʹ09.4ʺ N, 127°51ʹ55.2ʺ E • 1 LSN; 2018–2019 (Tables 1 and S1).

Description

LAST-STAGE NAUPLIUS (LSN). Lecithotrophic. Body spoon-shaped in dorso-ventral view; 1.8 times as long as wide; cephalic shield elliptical, with sharp discontinuity in body outline leading into trunk. In lateral view, trunk axis downturned ca 35° with respect to cephalic axis. Length ca 270 µm (ventral view in life, without dorso-caudal spine), greatest width 160 µm, greatest dorso-ventral thickness ca 115 µm. Labrum with goblet-shaped outline; in ventral view with free posterior margin extended into large medial spine, preceded by ca six large, equal-sized posteriorly directed spines on labral midline; pore pattern not examined. Caudal end attenuate, terminating in robust, 67 µm-long dorso-caudal spine set with smaller spines and accompanied ventrally at base by pair of triangular furcal spines ca 12 µm long; long axis of dorso-caudal spine upturned 25° with respect to trunk axis.

CYPRID VIEWED THROUGH CUTICLE OF LSN. Body weakly brownish, with thick strand of orange yolk granules in gut-like central tube. Other details not discernable in the single specimen examined.

Identification and variation

Recognizable by the combination of its general shape, size and spiny-keeled labrum.

Distribution

Japan (Sesoko Island, Okinawa).