Bathykorus bouilloni, Raskoff, Kevin A., 2010

Raskoff, Kevin A., 2010, Bathykorus bouilloni: a new genus and species of deep-sea jellyfish from the Arctic Ocean (Hydrozoa, Narcomedusae, Aeginidae), Zootaxa 2361, pp. 57-67 : 61-62

Bathykorus bouilloni gen. nov. sp. nov.

( Figures 1–4 )

Synonymy. “Unidentified narcomedusa” in Raskoff et al. 2005. “Narcomedusa” in Holland 2006. “New Narcomedusa” in Raskoff et al. In press. “ Narcomedusae sp. nov.” in Kosobokova & Hopcroft In press. “new narcomedusa” in Bluhm et al. In press.

Type material. The holotype and four paratype specimens have been deposited at the Smithsonian, National Museum of Natural History, Invertebrate Zoology Collection. USNM 1125360 Holotype, station 5, Canada Basin (73º 22' N; 153º 36' W), 4 July 2005 at 1607m depth. USNM 1125361, Paratypes, station 8, Canada Basin (74º 34’ N; 151º 56' W), 11 July 2005 at 1514 m depth; four specimens.

Etymology. The generic name Bathykorus references the habitat and shape of the species. Bathy (Greek; from bathus, depth or deep) refers to the deep-sea habitat of the species, and korus (Greek; helmet) refers to the helmet-like shape of the bell. The specific epithet of bouilloni is named in honor of the late Dr. Jean Bouillon, (1926–2009). Dr. Bouillon’s studies spanned over 60 years, and described 17 families, 34 genera, and 114 species. His work and his generous sprit continue to enlighten and inspire generations of biologists.

Diagnosis. Generic Diagnosis

Figures

FIGURE 1. Bathykorus bouilloni. All photographs obtained from a live specimen. A. Entire swimming medusa showing the positions of the primary and secondary tentacles, as well as the three interradial manubrial pouches per quadrant. B. Close up view of the base of the secondary tentacle and statocyst showing the 7 statoliths. sc, statocyst; st, secondary tentacle (scale bar = 200 µm). C. Close up view of the entire secondary tentacle (scale bar = 200 µm). D. Aboral view of one full quadrant of the medusa. m, mouth; mp, manubrial pouch; pt, primary tentacle; st, secondary tentacle; rt, tentacular root (scale bar = 1000 µm). E. Close up of the primary tentacular root (rt) (scale bar = 1000 µm).

FIGURE 2. Cnidome of Bathykorus bouilloni. A. Primary tentacle showing the characteristic endodermal chordal cells (ch) inside the tentacle and the asymmetrical distribution of the nematocysts on the aboral (right) side of the tentacle (nc). B. Close up view of chordal cells and cellular matrix at the core of the tentacle. C. Undischarged nematocysts on tentacle showing the two main size classes. Coiled threads can be seen inside the capsules. D. Discharged large and small apotrichous isorhizae nematocysts. All scale bars = 50 µm.

FIGURE 3. Histogram of nematocyst sizes in Bathykorus bouilloni. Nematocyst diameters (n = 105) were measured from a random assortment of microscopic video stills taken of a live specimen. There are two statistically different size classes (Mann-Whitney rank sum, P = <0.001).

FIGURE 4. Horizontal and vertical distribution of Bathykorus bouilloni in the Canada Basin, Northwind Ridge and Chukchi Plateau Region, summer 2005. The number of individuals observed per hour by the ROV is presented in 100 m depth bin intervals, from the surface to the maximum depth achieved for a particular station (see Table 1). The bottom depth, when within the ROV’s depth range, is shown in gray.