Bolinopsis vitrea L. Agassiz 1860

Bolinopsis vitrea (L. Agassiz, 1860)

(Fig. 3; Table 2)

Material examined. Oaxaca, Mexico: More than 100 specimens observed in the field; one specimen 60 mm long at Corralero Lagoon, 16°12'57.85" N, 98°11'8.07" W, 21 November 2013, coll. M.L. Rodríguez-Medellín, placed in 96% ethanol, dissolved after 24 h; 3 specimens at Puerto Ángel, 15°39'31'' N, 96°28'51'' W, 0 4 January 2014, coll. F. Ruiz-Escobar, placed in 1% trichloroacetic acid, without satisfying results; bloom of adults observed at Zipolite, 15°38’55’’ N, 96°31’30’’ W, 11 January 2014, 16 specimens, coll. F. Ruiz-Escobar and D.K. Valadez- Vargas, different specimens placed in 50% ethanol and 0.5, 1, 2 and 5% formalin solutions, without satisfying results; 1 specimen at Punta Cometa, 15°39'12.03" N, 96°33'27.98" W, 9 November 2014, coll. F. Ruiz-Escobar, transferred to the laboratory for photography.

Description. Translucent body, pear shaped (Fig. 3 A), slightly compressed in the tentacular plane (Fig. 2 B). Apical organ not at the aboral extremity, but in a pit or groove with a depth of about 1/5 of the distance between the aboral extremity and the mouth (Fig. 3 A, C). A long pharynx, deeply compressed in the tentacular plane, tapering to the aboral end near the apical organ. Vestigial axial tentacles only, limited to the tentacular sheath (Fig. 3 E). Lacking warts on the body surface. Subtentacular ctene rows about half the length of the substomodeal ctene rows. Auricles arising between the oral extremity of the subtentacular comb rows and the end of the oral groove, not reaching orally more than the mouth level. Lobes about half the length of the distance between the mouth and the aboral extremity. No gonads observed.

Remarks. The morphology and morphometric analysis of the specimens accords with the description of the species by Oliveira & Migotto (2006), except for the absence of conspicuous dark-red spots inside the canals in the lobes. This species differs from B. infundibulum, found further north and to the Arctic, primarily in size (B. vitrea is smaller) and the absence of dark pigmentation along the canals inside the lobes.

Distribution. This species was previously recorded by Bigelow (1912) in Acapulco harbor, Guerrero, Mexico, and at the Galápagos Islands, Ecuador (Bigelow 1912; Alvariño & Leira 1986). It is apparently a cosmopolitan species (Harbison et al. 1978), with records from the Atlantic Ocean (Moser 1910; Mayer 1912; Oliveira & Migotto 2006), Gulf of Mexico (Moss 2009) and the Mediterranean Sea basin (Shiganova & Malej 2009; Öztürk et al 2011). Although Mills & Haddock (2007, p.198) affirm that “ Bolinopsis off central Mexico are apparently B. vitrea ”, no official record of the species has previously been determined for northeastern Pacific waters.

Total length of the body 35.2 mm

Maximum width of the body 24.6 mm

Distance between lobe grooves at auricles base 13.4 mm

Distance between lobe grooves at mouth margin 7.3 mm

Length of the subtentacular ctene rows 14.4–14.6 mm Length of the substomodeal ctene rows 25.8–28.9 mm Maximum width between substomodeal and subtentacular ctene rows 7.45 mm

Maximum width between subtentacular ctene rows 7.08 mm

Number of ctene plates in subtentacular ctene rows 34–39

Number of ctene plates in substomodeal ctene rows 62–70

Diameter of the meridional canals up to 284 µm Width of the ctene plates 150–718 µm Distance between ctene plates 151–581 µm Length of the pharynx 15.8 mm

Maximum width of the pharynx 2.8 mm

Length of the auricles 6.7–7.1 mm Maximum width of the auricles 3.7–3.9 mm Diameter of the statocyst 200 µm