Sagitta bipunctata Quoy & Gaimard, 1827

Choo, Seohwi, Jeong, Man-Ki & Soh, Ho Young, 2022, Taxonomic reassessment of chaetognaths (Chaetognatha, Sagittoidea, Aphragmophora) from Korean waters, ZooKeys 1106, pp. 165-211 : 165

Sagitta bipunctata Quoy & Gaimard, 1827

Sagitta bipunctata : Quoy & Gaimard, 1827: 232-233 p., figs 1, 2, 6, 7; Aida 1897: 13-14 p., fig. 1; Ritter-Záhony 1908: 15 p., figs 2, 2A; Ritter-Záhony 1910: 2 p., Fowler 1906: 68 p.; Sund 1961: 110 p., table 1; Alvariño 1967: 44-49 p., fig. 26A-D; Dallot and Ducret 1969: 19 p., table 1; Srinivasan 1979: 8-9 p., fig. 3A-F; Michel 1984: 17-18 p., fig. 18; McLelland 1989: 163-164 p., figs 9A, 12I; Villenas and Palma 2006: 105 p., table 1

Material examined.

Yellow sea (33°0.111'N, 125°29.581'E), 0 - 86 m depth, oblique towing, July 2020.

Description.

Small, rigid and opaque body. Small head. Collarette almost absent (thin on neck). Eyes square-shaped with no eye pigments observed in this study. Intestinal diverticula absent. Forward end of anterior fins not visible. Posterior fins beginning in front of caudal septum and closing to seminal vesicles, completely rayed. Seminal vesicles elongated with small indentations and touching both lateral and caudal fins.

Distribution.

This species is found in the epipelagic (0-200 m depth) and mesopelagic zones (200-500 m depth) of Pacific, Indian and Atlantic Oceans ( Pierrot-Bults and Nair 1991). This species appears in most of the seas across Korean waters.

Ecology.

Sagitta bipunctata is known as a cosmopolitan species, appearing in temperate and tropical seas; it is an indicator species of high salinity and the presence of oceanic water (Pierce 1953). The temperature range in sampling stations of this study was 15.08-22.17 °C and the salinity range was 31.77-34.01 psu.

Remarks.

Only one immature individual was collected in this study. Sagitta bipunctata can be distinguished from other Korean species by the following characteristics: absence of intestinal diverticular, presence of completely rayed lateral fins and the restricted position of collarette on the posterior part of the body. The seminal vesicles of Korean specimen were not sufficiently mature compared to the description of Alvariño (1967).