Megacalanus princeps Wolfenden, 1904

Megacalanus princeps Wolfenden, 1904 View in CoL

(Fig. 1)

Material examined. 1 Male [Total length (TL) 9.9 mm], Rocas Atoll, #ST-14, Leg. 1 water column, 510 m depth, initial coordinate tow: 03°58’S 34°03’W, final coordinate tow: 03°57’S 34°04’W, 6 October 2015, MOUFPE 15581 View Materials GoogleMaps . 1 female (TL 9.21 mm) and 1 male (TL 10.31 mm), Rocas Atoll, #ST-22/Leg. 1 water column, 525 m depth, initial coordinate tow: 04°07’S 33°47’W, final coordinate tow: 4°07’S 33°48’W, 8 October 2015, MOUFPE 15658 View Materials GoogleMaps .

Distribution (Fig. 2). West Atlantic Ocean: Greenland, Iceland (W), Canada (Newfoundland), USA (Woods Hole, New Scotia, Carolinas, Florida), Bermudas (32°10’N 64°30’W), Sargasso Sea, Gulf of Mexico, Dominican Republic, Caribbean Sea, Brazil (Rio Grande do Norte: Rocas Atoll), Antarctic (Drake passage). East Atlantic Ocean: Faroe Island, Ireland (S & W), Spain (Bay of Biscay, Cape Finisterre, Canary Island), Portugal (Azores, Madeira Islands), Mediterranean Sea (Ligurian Sea, Tyrrhenian Sea, Gulf of Gabès, Ionian Sea, Alexandria), Ibero-moroccan Bay, Morocco, Mauritania-NW, Cape Verde Island, São Tomé Island, Angola, Saint Helena Island, South Africa. Indian Ocean: Arabian Sea, Bay of Bengal. Indonesia- Malaysia. West Pacific Ocean: Japan (Hokkaido), China, Taiwan, Philippines, New Caledonia, New Zealand, SubAntarctic (SW & SE Pacific). East Pacific Ocean: USA (Gulf of Alaska, Saint Paul Island, California, Hawaii), Canada (British Columbia), Peru (San Lorenzo Island), Chile (Juan Fernandez Island) ( Gueredrat, 1969; Hsiao et al., 2004; Razouls et al., 2005 –2016; this study).

Bathymetric distribution. The specimens examined were found at a depth of 525 m, in accordance with Miller (2002) and Hsiao et al. (2004), but their occurrence is usually between 300–2000 m.

Remarks. The specimens examined presented the same characteristics than those reported by Wolfenden (1904). Segmentation and setation patterns from swimming legs and maxilla were the same of that observed by Bradford-Grieve (1994). Also, the proportional length of urosomites and furca was different than the one found by Tanaka (1956); which found a proportional length from 41:20:15:7:17, while we found 33:23:13:8:23, indicating a small morphological variation, when compared with specimens collected in the Pacific Ocean. The specimens have long rostral filaments as observed by Sars (1924) and Tanaka (1956). Finally, as observed by Miller (2002), the specimens found here presented a cephalic crest; this characteristic was only found before in specimens collected in deep waters off Southern California.Probably due to the low sampling effort, scarcity in meso-bathypelagic collections and the increasing of deeper waters studies in Brazil, the spatial distribution of M. princeps was not known in this region. The occurrence of M. princeps in Brazilian waters expands its world distribution and increases the knowledge about zooplankton species from south Atlantic deep waters.