170 
Pneumatophore without apical pore. Gastrozooids without pedicle. 
Dioecious. 
REMARKS. As noted in the Introduction, both Lens and van 
Riemsdijk (1908) and Bigelow (1911) considered the genus Erenna 
might be related to the physonect family Forskaliidae, whereas 
Moser (1925) associated it with bathyphysid cystonects. However, 
Totton (1965) placed Erenna in the physonect family Agalmatidae. 
As Pugh (1998) discussed, the Agalmatidae is probably a composite 
family containing all those species that do not have the distinctive 
characters of other physonect families. There is a core of similar 
genera, Agalma, Halistemma and Lychnagalma, which have 
involucrate tentilla, with tightly coiled cnidobands. Nanomia is 
somewhat similar. However, the other genera are often difficult to 
relate to each other in any basic way. 
Pugh (1999) discussed this further, with regard to the genus 
Bargmannia, which Totton (1965) had placed in the family 
Pyrostephidae. Among the key characters used in establishing the 
taxonomic position of that genus were the ridge pattern on the 
nectophores; the presence of a muscle-free zone on the nectosac; and 
the structure of the tentillum. With regard to the ridge pattern, which 
consisted of pairs of apico-, infra and vertical (meso-) laterals, he 
noted that a similar arrangement was found on the nectophores of 
Pyrostephos vanhoeffeni Moser, 1925 and Erenna richardi; with an 
even simpler arrangement, omitting the vertical laterals, being 
found in Marrus species. Similarly, all these species had a muscle- 
free zone on the nectosac. In addition, Bargmannia species, P. 
vanhoeffeni and M. antarcticus were known to be dioecious, whereas 
most other physonects are known to be monoecious. In the present 
study it will be shown that two Erenna species are dioecious, with 
monovan gonophores; while gonophores were not found with the 
other two species. These characters separate these four genera from 
all other agalmatids. 
In Bargmannia spp., Pyrostephos vanhoeffeni and Marrus spp. 
the tentilla have simple, straight, or loosely coiled, cnidobands; with 
long contractile terminal filaments bearing nematocysts. However, 
Erenna richardi has a straight, hypertrophied cnidoband; and a rigid 
terminal process devoid of nematocysts. There are also differences 
in the types of nematocysts present on the tentillum. For many 
agalmatids four types are present: homotrichous anisorhizas 
(haplonemes), and either mastigophores or stenoteles on the 
cnidoband; desmonemes and acrophores in the terminal filament. 
The tentillum of Marrus species appears to conform with this 
pattern, with microbasic mastigophores included in the cnidoband. 
In Bargmannia species and P. vanhoeffeni large nematocysts, prob- 
ably stenoteles, were present only on the proximal part of the 
cnidoband; with two types of smaller nematocysts present through- 
out the remainder of the cnidoband and terminal filament. Pugh 
(1999) was uncertain whether the latter were acrophores or 
desmonemes, but haplonemes were thought to be absent. As is 
shown below, the cnidobands of Erenna species contain 
mastigophores and two types of haplonemes; but, as noted above, 
there are no nematocysts on the terminal process. 
Pugh (1999) concluded that there were sufficient similarities 
between Bargmannia spp. and Pyrostephos vanhoeffeni to retain the 
former in the family Pyrostephidae. However, despite the similari- 
ties of the nectophoral ridge pattern and the muscle-free zone on the 
nectosac, there are certain marked differences between these species 
and those of the genus Erenna. This particularly applies to the 
structure of the tentillum and its nematocysts; but also to the general 
structure of the nectophore. Pyrostephid nectophores have a large 
triangular thrust block and the axial wings are either reduced or 
absent; with the lateral radial canals on the nectosac arising separately 
P.R. PUGH 
from the dorsal canal. In Erenna spp. the thrust block is much 
smaller, while the apical wings are well-developed, and all four 
radial canals arise from the pedicular canal either together, or very 
nearly so. In addition, palpons with palpacles (reduced tentacles) are 
present in Erenna species, while they are totally absent in Bargmannia 
spp., or highly modified into palpacle-less oleocysts in P. vanhoeffeni. 
Also the female gonophores of the pyrostephids contain more than 
one ovum, while those of Erenna, where known, are monovan. 
These differences are here considered to be sufficient differences to 
warrant the establishment of a new family for the Erenna and closely 
related species described herein. The exact status of the genus 
Marrus remains uncertain, as Pugh (1999) discussed. 
Erenna Bedot, 1904 
Erenna Bedot, 1904: 10-14. 
DIAGNOSIS. Nectophores dorso-ventrally flattened with tapering 
axial wings; apico- and infra-lateral ridges respectively form upper 
and lower margins of lateral surface, with short, perpendicular, 
vertical lateral ridge connecting them. Lateral radial canals straight, 
thickened on apico-lateral margins of nectosac; with or without 
additional small protuberances, spikes, or ‘horn’ canals. Bracts of 
two types, both with patches of epidermal cells, including 
nematocysts, on dorsal swelling at distal extremity. Tentillum large, 
with hypertrophied, uncoiled cnidoband, and rigid terminal process 
devoid of nematocysts. Gastrozooid with large swollen basigaster, 
but no obvious pedicle. 
Erenna richardi Bedot, 1904 
Erenna richardi Bedot, 1904: 10-14, Pl. Il, figs. 1-12 
Erenna bedoti Lens & van Riemsdijk, 1908: 66-69; Margulis, 1977: 
148-151, 1990: 138-142. 
MATERIAL EXAMINED. The description is based largely on a speci- 
men collected during Johnson-Sea-Link (JSL) If Dive 1456 (2 xi 
1987; 24° 00.9'N 82° 15.7'W; depth 871 m). In addition, parts of 
another large specimen collected during JSL I Dive 2889 (19 xii 
1990; 26°22.3'N 78°46.2'W; depth 701 m) have been examined. 
These parts have been donated to The Natural History Museum, 
London, where they are registered as BMNH 2000.1819. Unfortu- 
nately, the remainder of the specimen, including the siphosome, has 
dried up. 
DIAGNOsIS. Nectophores large, flattened, with prominent apico-, 
infra- and vertical lateral ridges; plus at least two pairs of indistinct 
and incomplete laterals in basal half; apico-laterals divide close to 
ostium. Thrust block large with, in mature nectophores, two small 
digitate protuberances on ventral surface. Radial canals black 
pigmented; lateral ones with thickened walls in region of lateral 
margin of nectosac; with small protuberances or spikes. Gastrozooids 
black pigmented, particularly in greatly expanded basigaster, with 
two prominent lateral lobes. Tentillum with hypertrophied cnidoband, 
and long rigid distal terminal process with a diverticular canal and a 
pair of ‘ocelli’ close to its end. 
DESCRIPTION. An image (Fig. 1) taken from a video of the in situ 
JSLII Dive 1456 specimen shows the biserially arranged nectophores 
and the contracted siphosome. 
PNEUMATOPHORE. Pneumatophore ovoid, measuring 7 by 4 mm. 
Margulis (1977) noted the presence of eight vertical septa on her 
specimen, but these were not visible on the present material. 
NECTOPHORE. (Figs 2 & 3). About 45 nectophores, at various 
