
Fig. 17 Erenna cornuta. A. young tentillum of first type. Scale 0.5 mm. 
B. Two views of mature tentillum of first type. Scale 1 mm. 
contraction in the length of the pedicle itself. The canal penetrated 
through the saccus of the cnidoband to its tip. The saccus was largely 
filled by large, vacuolate gastrodermal cells that formed a reticulate 
pattern. The nematocysts were restricted to four circular swellings; 
two lateral, one proximal, one distal. Three types of nematocysts 
were present and arranged so that the larger anisorhizas, measuring 
c. 130 x 35 um, surrounded the smaller (?) haplonemes; the more 
cylindrical ones measuring 32 x 11 tm, and the more ovoid ones 41 
x 14 um. 
The youngest of the other type of tentillum (Fig. 18A) comprised 
a short, thickened pedicle, a long cnidoband, and a short terminal 
process, which had a circular spot of distinctive epidermal cells on 
one side. The broad gastrovascular canal was present throughout 
and, in the terminal process, it appeared to bend back and continue, 
for a short distance, toward the saccus of the cnidoband. However, 
even in the smallest tentilla examined, the saccus had already been 
occluded by gastrodermal cells. The nematocysts had begun to 
accumulate into an undulating series of connected swellings on one 
side of the saccus. 
Only a few mature tentilla (Fig. 18B) of the second type were 
found with the specimen. In these the pedicle remained short and 
broad and was largely filled by the gastrovascular canal. The 
cnidoband had increased greatly in length and was largely filled by 


Fig. 18 Erenna cornuta. A. Young tentillum of second type. Scale 0.5 
mm. B. Mature tentillum of second type. Scale | mm. 
P.R. PUGH 
large, vacuolated gastrodermal cells. The narrow gastrovascular 
canal passed through its middle and opened into the cavity of the 
small, spherical, thin-walled terminal process. The patch of cells 
persisted on one side of the latter. No diverticular branch of the main 
canal could be discerned. On the cnidoband the rounded swellings 
containing the nematocysts became more or less separated one from 
another. On the two best preserved mature tentilla there were 17 of 
these patches. The nematocysts were of the same type and size as on 
the other type of tentillum. 
PALPON. (Fig. 16B). The globular, thin-walled palpons meas- 
ured up to c. 4 mm in length. There was a short, narrow proboscis, 
at the base of which was a ring of pigmented gastrodermal cells, 
often organised into distinct spots. Other concentrations of 
gastrodermal cells sometimes were visible, particularly on the 
distal part of the stomach region. The base of the stomach region 
was almost surrounded by a small, loosely attached, horseshoe- 
shaped region of large, vacuolated epidermal cells, with the 
palpacle being attached in the open region. No nematocysts were 
found on the palpacle. 
GONODENDRON. No gonodendra were found on the small piece of 
siphosome that remained with the specimen. 
DISTRIBUTION. The type specimen came from the region of the 
Dry Tortugas, between Florida and Cuba. Nectophores with ‘horn’ 
canals, which presumably can be referred to this species, have been 
collected at four recent Discovery stations. Two of these were at c. 
30°N 23°W at depths of 1250-1500 m and 1500—2000m, and the 
other two from off Bermuda (c. 31°45'N 63°45'W) at depths of 
1250-1500m. 
ETYMOLOGY. The specific name, meaning ‘horned’ in Latin, re- 
fers to the ‘horn’ canals present in most of the nectophores. 
Parerenna gen. nov. 
DIAGNOSIS. Nectophores not dorso-ventrally compressed; with 
muscle-free zone on nectosac mainly on lower surface adaxially. 
Vertical lateral and incomplete infra-lateral ridges very indistinct; 
the latter not forming the lower margin of lateral surface. Apico- 
laterals peter out well above ostial level. Gastrozooid with minute 
basigaster. Tentillum with long pedicle; with cnidoband extending 
beyond terminal process, which has a small spherical distal swell- 
ing. 
Monotypic genus to accommodate Parerenna emilyae sp.nov. 
Parerenna emilyae sp.nov. 
HOLOTYPE. The specimen from JSL I Dive 2886 is designated 
holotype, and has been donated to the Natural History Museum, 
London where it is registered as BMNH 2000.1820. 
MATERIAL EXAMINED. A single specimen collected during JSL I 
Dive 2886 (18 xii 1990; 26°31.8'N, 78°05.6'W; depth 823 m). 
Before preservation in 5% buffered formalin, the bioluminescence 
of the specimen was studied which, unfortunately, resulted in the 
loss of some parts. 
DIAGNOSIS. As for genus. 
DESCRIPTION 
PNEUMATOPHORE. ‘The base of the pneumatophore has exploded 
due to the expansion of the gas contents while bringing the specimen 
to the surface. Pneumatosaccus spherical, c. | mm in diameter, with 
a small cap of cells, which may have been pigmented in life. 
